The Speed of Light--The same for all reference frames/observers?

[Bob K]

The Speed of Light--The same for all reference frames/observers?

Is the speed of light, SOL, really the same for any and all reference frames?

Gedankenexperiment:

Lightsource<------------------------------------->Target

Lightray A: -------------------------------------> Target

Lightray B: -------Spaceship---------------------> Target

Lightray A is emitted from Lightsource simultaneously with and parallel to Lightray B towards a single Target.

If Lightray A and Lightray B are emitted simultaneously and parallel to each other from Lightsource, then they should strike Target simultaneously.

Lightray B passes through a rear window of Spaceship and out a front window.

Spaceship is traveling towards Target parallel to Lightray A. [Spaceship could be traveling away from Target towards Lightsource.]

Assume there are no physical reasons why Lightray B should be obstructed or otherwise impeded within Spaceship.

Assume also that the SOL is measured when it ‘goes past’ the center of mass/inertia of Spaceship to eliminate theoretical relativistic length-contraction problems.

Spaceship is one reference frame and the Lightsource<->Target continuum is another reference frame.

NOTE: This is a Special Relativity condition wherein two reference frames are traveling at a uniform/constant velocity/motion relative to each other. The conclusions of this gedankenexperiment are the same for General Relativity conditions wherein one reference frame is accelerating and/or rotating and thus not traveling in uniform/constant velocity/motion relative to another reference frame (providing that Lightray B enters a rear window of Spaceship and exits a front window).

The SOL is supposed to be the same for all reference frames.

If the SOL is the same for all reference frames, Lightray B should exit Spaceship’s front window ahead of/in advance of Lightray A, because it would have had to have been speeded up--a theoretical impossibility--by traversing the reference frame of Spaceship/going past the center of mass/inertia of Spaceship at SOL while Lightray A is merely traversing the Lightsource<->Target reference frame, thus Lightray B should strike Target ahead of/in advance of Lightray A.

Question: When does Lightray B strike Target?

If simultaneous with Lightray A, then the SOL inside the reference frame of Spaceship is not the same as the SOL outside the reference frame of Spaceship--the SOL going past the center of mass/inertia of Spaceship is slower than the SOL of the Lightsource<->Target reference frame--a theoretical impossibility according to relativity.

If non-simultaneous with Lightray A, but in advance of Lightray A, then the SOL inside the reference frame of Spaceship is SOL relative to the center of mass/inertia of Spaceship but faster than the SOL of the reference frame of Lightsource<->Target, which is theoretically impossible according to relativity.

So, place your bets--when does Lightray B strike Target?

Yes, I have an answer, and part of the answer involves a statement which is true: The speed of light is the same for all observers.

More later.

[Jesse]

Originally posted by Bob K
The SOL is supposed to be the same for all reference frames.

If the SOL is the same for all reference frames, Lightray B should exit Spaceship’s front window ahead of/in advance of Lightray A, because it would have had to have been speeded up--a theoretical impossibility--by traversing the reference frame of Spaceship/going past the center of mass/inertia of Spaceship at SOL while Lightray A is merely traversing the Lightsource<->Target reference frame, thus Lightray B should strike Target ahead of/in advance of Lightray A.

That isn't how frames of reference work--the light going through the ship is not temporarily entering the ship's reference frame and then exiting it. A frame of reference is not a local region of space that travels around with the spaceship, it's just a coordinate system that fills all of spacetime and is used for describing the location of any event in spacetime (in terms of x,y,z,t coordinates). When a physicist talks about the "spaceship's reference frame" he just means a universal coordinate system in which the ship is at rest--its spatial coordinates x,y, and z do not at different values of the time coordinate t. In this coordinate system, both the lightsource and the target will have some constant velocity. In the reference frame of the lightsource/target, they will be at rest while the ship is moving at a constant velocity. You can describe the whole sequence of events entirely in either one of the two reference frames, you should get the same answer about physical questions which are not reference-frame-dependent (for example, if the two light beams were at a slight angle so that they hit the target on exactly the same point, the question of whether they hit that point simultaneously should be the same regardless of which reference frame you choose).

Bob K:
Question: When does Lightray B strike Target?

If simultaneous with Lightray A, then the SOL inside the reference frame of Spaceship is not the same as the SOL outside the reference frame of Spaceship--the SOL going past the center of mass/inertia of Spaceship is slower than the SOL of the Lightsource<->Target reference frame--a theoretical impossibility according to relativity.

If non-simultaneous with Lightray A, but in advance of Lightray A, then the SOL inside the reference frame of Spaceship is SOL relative to the center of mass/inertia of Spaceship but faster than the SOL of the reference frame of Lightsource<->Target, which is theoretically impossible according to relativity.

No, you're mistaken about how what relativity predicts, and you seem to be confused about the whole concept of a "reference frame". Different reference frames do disagree about whether spatially separated events are "simultaneous" or not, which is why I suggested the condition of having the light beams at just the right angle so they converge at the same point on the target. But as long as you include this condition, in both reference frames you get the same prediction: the light beams will strike the target at the same place and time.

[ex-xian]

Originally posted by Bob K
Assume there are no physical reasons why Lightray B should be obstructed or otherwise impeded within Spaceship.
You mean the light isn't reflected or refracted and there is a vaccuum inside the ship?

Assume also that the SOL is measured when it ‘goes past’ the center of mass/inertia of Spaceship to eliminate theoretical relativistic length-contraction problems.
Time dilation and length contraction would be based on the speed of the ship. How fast is the ship going anyway--not that it would matter, I think.
If the SOL is the same for all reference frames, Lightray B should exit Spaceship’s front window ahead of/in advance of Lightray A, because it would have had to have been speeded up--a theoretical impossibility--by traversing the reference frame of Spaceship/going past the center of mass/inertia of Spaceship at SOL while Lightray A is merely traversing the Lightsource<->Target reference frame, thus Lightray B should strike Target ahead of/in advance of Lightray A.
No, the speed of light is indepedent of reference frame. It wouldn't be speeded up just because it passes through a moving medium.

Question: When does Lightray B strike Target?
It hits with A.

Yes, I have an answer, and part of the answer involves a statement which is true: The speed of light is the same for all observers.
By all means, share your answer. Also, what is your background in math and physics?

[spacer1]

BobK,
...like every other general law of nature, the law of transmission of light in vacuo must, according to the principle of relativity, be the same for the railway carriage as reference-body as when the rails are the body of reference. But, from our above consideration, this would appear to be impossible. If every ray of light is propagated relative to the [stationary] embankment with the velocity c, then for this reason it would appear that another law of propagation of light must necessarily hold with respect to the [moving] carriage - a result contradictory to the principle of relativity.

In view of this dilemma there appears to be nothing else for it than to abandon either the principle of relativity or the simple law of the propagation of light in vacuo. Those of you who have carefully followed the preceding discussion are almost sure to expect that we should retain the principle of relativity. The development of theoretical physics shows, however, that we cannot pursue this course. The epoch-making theoretical investigations of H. A. Lorentz on the electrodynamical and optical phenomena connected with moving bodies show that experience in this domain leads conclusively to a theory of electromagnetic phenomena, of which the law of the constancy of the velocity of light in vacuo is a necessary consequence. Prominent theoretical physicists were therefore more inclined to reject the principle of relativity, in spite of the fact that no empirical data had been found which were contradictory to this principle. [The principle is not to be confused with the theory of relativity. The principle is stated as: "If, relative to K, K' is a uniformly moving co-ordinate system devoid of rotation, then natural phenomena run their course with respect to K' according to exactly the same general laws as with respect to K." p. 16]

At this juncture the theory of relativity entered the arena. As a result of an analysis of the physical conceptions of time and space, it became evident that in reality there is not the least incompatibility between the principle of relativity and the law of propagation of light, and that by systematically holding fast to both these laws a logically rigid theory could be arrived at. This theory has been called the special theory of relativity....

Relativity - The Special and the General Theory by Albert Einstein, 1961, Three Rivers Press. pp. 22-24.

[Bob K]

Jesse

Bob K: The SOL is supposed to be the same for all reference frames.

If the SOL is the same for all reference frames, Lightray B should exit Spaceship’s front window ahead of/in advance of Lightray A, because it would have had to have been speeded up--a theoretical impossibility--by traversing the reference frame of Spaceship/going past the center of mass/inertia of Spaceship at SOL while Lightray A is merely traversing the Lightsource<->Target reference frame, thus Lightray B should strike Target ahead of/in advance of Lightray A.

Jesse: That isn't how frames of reference work--the light going through the ship is not temporarily entering the ship's reference frame and then exiting it. A frame of reference is not a local region of space that travels around with the spaceship, it's just a coordinate system that fills all of spacetime and is used for describing the location of any event in spacetime (in terms of x,y,z,t coordinates). When a physicist talks about the "spaceship's reference frame" he just means a universal coordinate system in which the ship is at rest--its spatial coordinates x,y, and z do not at different values of the time coordinate t. In this coordinate system, both the lightsource and the target will have some constant velocity. In the reference frame of the lightsource/target, they will be at rest while the ship is moving at a constant velocity. You can describe the whole sequence of events entirely in either one of the two reference frames, you should get the same answer about physical questions which are not reference-frame-dependent (for example, if the two light beams were at a slight angle so that they hit the target on exactly the same point, the question of whether they hit that point simultaneously should be the same regardless of which reference frame you choose).

According to Einstein’s book, Relativity, he used the example of a railway carriage reference frame traversing a railway embankment reference frame.

My Lightsource<->Target reference frame is the same as Einstein’s railway embankment reference frame and my Spaceship reference frame is the same as Einstein’s railway carriage reference frame.

Hence, from Einstein’s description of reference frames in his own book, the Lightsource<->Target/railway embankment is one reference frame and the Spaceship/railway carriage is another reference frame.

When the Spaceship/railway carriage is moving uniformly relative to the Lightsource<->Target/railway embankment, we have two, not one, reference frames, and the conditions necessary for SR.

If you continue to disagree with Einstein’s descriptions of reference frames, then we are lost because I have no idea of what you are talking about since Einstein himself in Relativity is my source of information re: reference frames and I am using an updated version of his example as my example.

Bob K:
Question: When does Lightray B strike Target?

If simultaneous with Lightray A, then the SOL inside the reference frame of Spaceship is not the same as the SOL outside the reference frame of Spaceship--the SOL going past the center of mass/inertia of Spaceship is slower than the SOL of the Lightsource<->Target reference frame--a theoretical impossibility according to relativity.

If non-simultaneous with Lightray A, but in advance of Lightray A, then the SOL inside the reference frame of Spaceship is SOL relative to the center of mass/inertia of Spaceship but faster than the SOL of the reference frame of Lightsource<->Target, which is theoretically impossible according to relativity.

Jesse: No, you're mistaken about how what relativity predicts, and you seem to be confused about the whole concept of a "reference frame". Different reference frames do disagree about whether spatially separated events are "simultaneous" or not, which is why I suggested the condition of having the light beams at just the right angle so they converge at the same point on the target. But as long as you include this condition, in both reference frames you get the same prediction: the light beams will strike the target at the same place and time.

I am not mistaken about how Einstein in his own book, Relativity, described reference frames and of his assumption/premise used for SR/GR that the laws of physics/physical phenomena including the SOL are to be the same for all reference frames, meaning that the SOL for the Lightsource<->Target reference frame is 186,000 mps ‘going past’ a reference point such as the midpoint between Lightsource and Target and that the SOL for Spaceship is 186,000 mps ‘going past’ the center of mass/inertia of Spaceship.

My point is that if Einstein’s premise/assumption that the SOL is 186,000 mps for all reference frames is correct/true, including Lightsource<->Target and Spaceship, then Lightray B traveling through the Spaceship reference frame would be advanced ahead of Lightray A when it exited the Spaceship reference frame and thus would strike Target ahead of Lightray A, but if Einstein is wrong and his assumption that the laws of physics are the same for all reference frames is not true/correct, then Lightray B would not be advanced ahead of Lightray A and both Lightray A and Lightray B would strike Target simultaneously.

Because Lightsource<->Target is one reference frame and Spaceship is another reference frame, and together they fit the description of SR conditions of reference frames moving with uniform/nonaccelerated motion relative to each other, then either Einstein’s assumption of the invariance of physical laws/phenomena is right and Lightray B hits Target ahead of Lightray A because it is accelerated by the motion of Spaceship’s reference frame/physical laws/phenomena or Einstein’s assumption is wrong and Lightray B hits Target simultaneous with Lightray A.

[Jesse]

Jesse:
That isn't how frames of reference work--the light going through the ship is not temporarily entering the ship's reference frame and then exiting it. A frame of reference is not a local region of space that travels around with the spaceship, it's just a coordinate system that fills all of spacetime and is used for describing the location of any event in spacetime (in terms of x,y,z,t coordinates). When a physicist talks about the "spaceship's reference frame" he just means a universal coordinate system in which the ship is at rest--its spatial coordinates x,y, and z do not at different values of the time coordinate t. In this coordinate system, both the lightsource and the target will have some constant velocity. In the reference frame of the lightsource/target, they will be at rest while the ship is moving at a constant velocity. You can describe the whole sequence of events entirely in either one of the two reference frames, you should get the same answer about physical questions which are not reference-frame-dependent (for example, if the two light beams were at a slight angle so that they hit the target on exactly the same point, the question of whether they hit that point simultaneously should be the same regardless of which reference frame you choose).

Bob K:
According to Einstein’s book, Relativity, he used the example of a railway carriage reference frame traversing a railway embankment reference frame.

My Lightsource<->Target reference frame is the same as Einstein’s railway embankment reference frame and my Spaceship reference frame is the same as Einstein’s railway carriage reference frame.

Hence, from Einstein’s description of reference frames in his own book, the Lightsource<->Target/railway embankment is one reference frame and the Spaceship/railway carriage is another reference frame.

When the Spaceship/railway carriage is moving uniformly relative to the Lightsource<->Target/railway embankment, we have two, not one, reference frames, and the conditions necessary for SR.

Sure, the motions of the objects define two different reference frames here--I wasn't arguing with that. But my point is that SR doesn't say you have to start out using the lightsource/target reference frame and then switch to the rocket reference frame when the beam travels through the rocket, then switch back to the lightsource/target frame when it leaves the rocket. Either reference frame can be used to describe the entire sequence of events, or any part of it--that's up to the person doing the calculation (he would even be free to use a third reference frame whose velocity does not correspond to that of any object in the problem). If you think that SR tells you which reference frame you must use in a given situation, you're totally confused, and I guarantee you won't find any quotes by Einstein that support that idea.

Let's flesh this out with some actual numbers, OK? Assuming all this happens in a single plane, let's use x,y, and t for the coordinates of of events in the lightsource/target frame (LT frame for short) and x', y' and t' for coordinates of events in the rocket frame (R frame for short). Also assume that the rocket is moving at 0.5 c in the +x direction in the LT frame, which of course means that the lightsource/target are moving at 0.5c in the -x' direction in the R frame (since the relative motion of the two frames is orthogonal to the y and y' axes, there's no Lorentz contraction or differences in simultaneity along these axes, so I'll mostly ignore them in my calculations).

Now, let's say that when the two beams are emitted by the light source, the event of the bottom beam being emitted is at coordinates x=0 meters (m), y=0 m and t=0 microseconds (µs) in the LT frame, which in the R frame is x'=0 m, y'=0 m and t'=0 µs...the origins of the two coordinate systems coincide at this point in spacetime. The second beam is emitted at coordinates x=0 m, y=2 m, and t=0 µs in the LT frame, which will correspond to x'=0 m, y'=2 m, and t'=0 µs in the R frame (again, there's no Lorentz contraction along the y-axis since it's orthogonal to the direction of motion).

In the LT frame, at the moment the light beams are emitted the back end of the rocket is at coordinates x=200 m, y=0 m, and t=0 µs; if the rocket is 10 m long in its own frame, then in the LT frame it will be only 8.66 m long due to the Lorentz contraction given by:

http://www.fourmilab.ch/cship/equations/length.gif

So, in the LT frame the front of the rocket at that moment will be at coordinates x=208.66 m, y=0 m, and t=0 µs. Finally, assume that in the LT frame the target is at coordinates x = 500 m and t = 0 µs, with some height along the y-axis large enough that both beams will strike it.

Let’s continue and look at all the subsequent events from the point of view of the LT frame. The light beam starts at x = 0 m and moves in the +x direction at 300 m/µs, while the back of the rocket starts at x = 200 m and moves in the +x direction at 150 m/µs. Solving 300t = 150t + 200 gives t = 1.333 µs for them to meet at x = 400 m. Then, solving for 300t = 150t + 208.66 shows that the light beam will meet the front of the rocket at t = 1.391 µs at x = 417.3 m. Finally, the light beam will hit the target at x = 500 m at t = 1.667 µs. Likewise, the upper beam will also hit its point on the target at x = 500 m and y = 2 m after t = 1.667 µs. To summarize, in the LT coordinate system the coordinates of the important events are:

Top beam emitted:
(0 m, 2 m, 0 µs)
Bottom beam emitted:
(0 m, 0 m, 0 µs)
Bottom beam passes back of rocket:
(400 m, 0 m, 1.333 µs)
Bottom beam passes front of rocket:
(417.3 m, 0 m, 1.391 µs)
Bottom beam hits target:
(500 m, 0 m, 1.667 µs)
Top beam hits target:
(500 m, 2 m, 1.667 µs)

It’s not hard to see from this that both beams do always travel at 300 m/µs in the LT frame.

Now, let’s switch over to the R frame. You’ll remember that in this frame the bottom beam is emitted at coordinates (0 m, 0 m, 0 µs) and the top at (0 m, 2 m, 0 µs) just like in the LT frame, but the coordinates of the rocket and the target at t' = 0 µs will be a bit different because different frames have different definitions of simultenaity. Here we can use the coordinate transformation formulas for special relativity:

x' = gamma*(x – vt)
t' = gamma*(t – vx/c^2)

(here, v is the velocity of the R frame with respect to the LT frame along the x-axis, or +0.5c = +150 m/µs…also, gamma = 1/[the square root of (1-v^2/c^2)] = 1.1547 in this case)

So, looking at the coordinates of the back of the rocket at its position when t = 0 µs in the LT frame, namely (200,0,0), we find the corresponding coordinates in the R frame to be x' = 230.940 m, t' = -0.385 µs. Since the R frame is the rocket’s rest frame, the x' coordinate of its back will not change over time in this frame, nor will the x' coordinate of its front (and since we said earlier that the rocket was 10 meters long, the unchanging x' coordinate of the front is x' = 240.940 m). The target, on the other hand, will be moving in the –x direction at 0.5c in the R frame; the initial coordinates of x = 500 m and t = 0 µs in the LT frame correspond to coordinates x' = 577.35 m and t' = -0.962 µs, and since it’s moving at 150 m/µs, at t' = 0 µs its position will have moved to x' = 433.05 m (which is exactly what you’d expect based on the Lorentz contraction equation, since in the LT frame the distance between the lightsource and the target is 500 m at any given moment, so at any given moment in the R frame it should be 500/gamma or 433.01 m…the difference in the last digit is just due to roundoff error).

The bottom beam started out at x' = 0 m at t' = 0 µs in the R frame, so at 300 m/µs it will reach x' = 230.940 m (the back of the rocket) at t' = 0.770 µs, and it will reach x' = 240.940 m (the front of the rocket) at t' = 0.803 µs. Since the target is moving towards the beam at 150 m/µs and it started at x' = 433.05 m when t' = 0 µs, we can solve 300t = -150t + 433.05 to see the beam will hit the target at t' = 0.962 µs, which would be at postion x' = 288.6 m.

These numbers were based on thinking about all the movements from within the R frame, but one should get the same answers (aside from roundoff errors) if one just converts the coordinates found in the LT frame using the conversions given earlier—you can check yourself to see that this works. For example, in the LT frame the coordinates of the event "light beam passes back of rocket" were x = 400 m, t = 1.333 µs, and using the formulas this translates to x' = 230.998 m and t' = 0.769 µs, very close to the values x' = 230.940 m and t' = 0.770 µs found earlier. Likewise, in the LT frame the coordinates of "light beam passes front of rocket" were x = 417.3 m, t = 1.391 µs; translating this into the R frame gives x' = 240.928 and t' = 0.803 µs, close to the x' = 240.940 m and t' = 0.803 µs found earlier. Finally, in the LT frame the coordinates of "light beam hits target" were x = 500 m, t = 1.667 µs, which translates into x' = 288.617 and t' = 0.963 µs, close to the values of x' = 288.6 m and t' = 0.962 µs which were obtained by just considering things from within the R frame.

So, in the R frame the approximate coordinates of important events were:
Top beam emitted:
(0 m, 2 m, 0 µs)
Bottom beam emitted:
(0 m, 0 m, 0 µs)
Bottom beam passes back of rocket:
(230.9 m, 0 m, 0.770 µs)
Bottom beam passes front of rocket:
(240.9 m, 0 m, 0.803 µs)
Bottom beam hits target:
(288.6 m, 0 m, 0.962 µs)
Top beam hits target:
(288.6 m, 2 m, 0.962 µs)

Again, it is simple to verify that the light beams were travelling at about 300 m/µs in the R frame as well.

So, you can see that the entire sequence of events can be calculated solely in the LT frame or solely in the R frame, you’ll get equivalent answers either way (and the speed of light will be the same in all frames). Likewise, you’re free to switch from one frame to another if you feel it’ll make calculations either. The choice is up to you—the theory of relativity itself doesn’t tell you anything about which frame you "should" use in any given circumstance.

(edited because I realized the speed of light is 300 meters/microsecond, not 300 meters/millisecond)

[Lobstrosity]

Originally posted by Bob K

My Lightsource<->Target reference frame is the same as Einstein’s railway embankment reference frame and my Spaceship reference frame is the same as Einstein’s railway carriage reference frame.

No, it's not. You seem to not understand the whole concept of frames of reference. Your thought experiment does not actually contain a "spaceship" reference frame. It consists solely of one reference frame in which the target is stationary. You then postulate what would happen if you add a moving spaceship to this frame without in any way considering the actual rest frame of the spaceship itself. This makes your thought experiment pointless. Perhaps you should reread Einstein as you don't seem to have actually digested what he was saying. An external observer is not in the frame of the spaceship. The external observer sees light moving at the speed of light (in vacuum, of course), not the speed of light plus the speed of the space ship when he sees that light "in" the spaceship. The spaceship in itself does not introduce a new frame until you actually put an observer in that frame. Such an observer would also observe that all light travels at the speed of light in vacuum even though the first external observer would perceive that the spaceship observer was actually moving with respect to the light.


Here's a thought experiment that demonstrates how to correctly use frames of reference:

Observer A is floating in space holding a laser. A spaceship containing observer B is travelling .9c and passes right by observer A (so there was a moment when they very nearly shared the same coordinates in spacetime). At this moment both observers set their watches to zero. When observer A's watch reads 10 seconds, he points the laser at the spaceship containing observer B and turns it on. What does he see his watch say when the photons hit the hull of the space ship (i.e. when they reach observer B, for all intents and purposes)? Well, that's easy. The laser is propagating at speed c and the ship is moving at speed .9c, so we can use simple algebra to determine that his watch says 100 seconds when the laser reaches observer B (the photons spend quite a while chasing the ship in observer A's frame). He can experimentally confirm this by tracking the spaceship with a telescope and then halving the time interval between when he turned on the laser and when he first sees it hit the hull.

Now, the question you ask when interested in determining whether the speed of light moves at the same speed in all reference frames is what time the watch of observer B's reads when he first sees the light from the laser. This is the kind of experiment that would test relativity. For completeness, I will tell you what relativity would predict. Relativity tells us that observer B considers himself stationary and instead sees observer A fly by at .9c. He's perfectly free to do this because all inertial frames are physically equivalent. Who's to say observer A isn't really the one moving? Now, observer B notes that time is running more slowly for observer A. As they pass he focuses a telescope on observer A's wrist watch and sees that its hands are moving more slowly than his own (even when he accounts for the for the observational slow down one would expect simply because the photons he was observing were coming from farther and farther away as time progresses). Specifically, he is able to calculate via observation (and via theory) that for every second that ticks on observer A's watch, approximately 2.29 seconds tick by on his own. This means that observer A's watch reads 10 seconds after 22.9 seconds have passed according to observer B. After 22.9 seconds, observer A is now 22.9s*.9c = 20.6 c*s away. At this point observer A turns on his laser. The light from the laser traverses this 20.6 light-seconds in 20.6 seconds. Therefore, the time on observer B's watch when the laser light reaches him is 22.9+20.6 = 43.5 seconds (barring any stupid algebraic errors). Obviously the same "event" takes longer in observer A's frame than it does in observer B's. In observer B's frame the light isn't chasing a ship that's retreating from it at near light speed. After this experiment was all said and done observer B could then turn his ship around, fly back to observer A, and compare notes.

As a final check, let's see if this last result is internally consistent. Let's say that observer A is watching observer B's watch with his telescope. What time does he see on B's watch when he sees the laser beam hit the hull? Well we note that observer A sees that time is running more slowly for observer B since he perceives B as moving. 2.29 seconds tick off of observer A's watch for every second that he sees tick off of observer B's watch. This means that when his watch reads 100 seconds (i.e. when the laser beam hits the hull) he knows that observer B's watch reads 43.7 seconds. Wow, everything is internally consistent. Observer B can observe what time A has and A can observe what time B has. When they come back and compare notes they will see that their observations were both correct. The time each had was clearly frame-dependent, but this did not introduce any problems at all. Paradoxes did not appear. Hooray.


You do know that experiments in this vein have been carried out, right Bob? For example, we know the half life of muons when they are at rest. We then observe that this half life increases as their speed in the laboratory increases exactly as relativity predicts.

So, in short, this statement of yours in the OP:
If the SOL is the same for all reference frames, Lightray B should exit Spaceship’s front window ahead of/in advance of Lightray A, because it would have had to have been speeded up--a theoretical impossibility--by traversing the reference frame of Spaceship/going past the center of mass/inertia of Spaceship at SOL while Lightray A is merely traversing the Lightsource<->Target reference frame, thus Lightray B should strike Target ahead of/in advance of Lightray A.
is completely erroneous and demonstrates a gross misunderstanding of relativity and frames of reference. Relativity does not tell us that the two lightrays in your thought experiment reach the targets at different times.

[pmurray]

Originally posted by Bob K
Assume also that the SOL is measured when it ‘goes past’ the center of mass/inertia of Spaceship to eliminate theoretical relativistic length-contraction problems.

But this is not possible. You can't measure the speed of something at a single point. To measure the speed of anything, you have to measure the time at it passes point A and the time at which it passes point B, subtract one from the other and divide by the distance. There's no other way to do it.

Even if A and B are very close together, observers inside and outside the spaceship will disagree about how far they are apart, and how much time elapsed. That's what relativity is about. Both observers, however, will agree that the SOL is about 3*10^8 m/s, and that the two light ray will hit the planet simultaneously.

[Jabu Khan]

I believe its the speed of light through free space is constant for all reference frames isn't it? So things like refraction would matter because its the speed of light through a medium.
Reference frames though are ways of showing the relative position and speed of an object observed by say a stationary object and an accelerating object. If your moving through space and look back at two objects passing each other they will appear to be alligned at a different point and time then someone standing stationary on the opposite side will observe them to be.
Likewise the speed of the objects would appear different when measured by the two observers, however both observers would measure the speed of light through free space to be the same.
Thats not to say that the objects aren't traveling at one speed just that the frame of reference must be taken into account except when measuring the speed of light through free space.
Thats how I understand it. Domeone let me know if I flubbed up.

[Jesse]

Jabu Khan:
I believe its the speed of light through free space is constant for all reference frames isn't it? So things like refraction would matter because its the speed of light through a medium.

Right, the speed of light through a medium wouldn't necessarily be the same in all frames.

Jabu Khan:
Reference frames though are ways of showing the relative position and speed of an object observed by say a stationary object and an accelerating object.

Two quibbles: first of all, the equivalence of reference frames in relativity only covers inertial reference frames, not accelerating ones. An inertial frame is one moving at a constant velocity relative to other inertial frames (there may be some circularity here, but you can also say that an inertial frame is one where if the object is moving through flat space, it does not experience the characteristic G-forces of acceleration). Second, velocity is always relative to a particular reference frame, relativity says there's no such thing as "true" or absolute velocity; so, "stationary" depends on your choice of reference frame.

Jabu Khan:
Likewise the speed of the objects would appear different when measured by the two observers, however both observers would measure the speed of light through free space to be the same.

Right, the velocity of any object moving at sublight speed will be different in different reference frames.

Jabu Khan:
Thats not to say that the objects aren't traveling at one speed just that the frame of reference must be taken into account except when measuring the speed of light through free space.

Well, like I said, relativity says there's no one speed that's the "true" speed of the object. But calculations in different frames will always give the same results for physical questions that don't depend on your reference frame, like whether two objects will collide or not.

[Bob K]

In the gedankenexperiment Target is singular--there is only one Target, and it is perpendicular to the pathways of Lightrays A and B. The distance traveled by Lightray A from Lightsource to Target is the same distance traveled by Lightray B from Lightsource to Target.

The pathways of Lightrays A and B are stipulated to be perfectly parallel to each other and so close together that light travel-distance problems between them are negligible and their pathways are perfect straight lines to eliminate any potential spacetime curvature confusions which might cause extraneous time differences of their strikes upon Target.

There is a gedankenexperiment-privilege stipulation [a stipulation/premise allowable by the nature of a thought-experiment--Einstein required them to require focus upon a concept or principle in his gedankenexperiments, so why would similar requirements not be possible/permitted for anyone else?] that there is no bending or retardation of either Lightray A or B due to physical effects such as the gravitational fields generated by any mass involved herein--the masses of Lightsource, Target and Spaceship do not generate gravitational fields which could bend the pathways of the Lightrays; likewise, there is a stipulation that there is no electromagnetic phenomena-caused deviations/retardations of the parallel/straight-line pathways of the Lightrays; by these stipulations, and any others not presently imagined but otherwise potentially required, arbitrary though they may be, the Lightrays are perfectly parallel to each other and travel in perfect straight lines and space curvature confusions are thereby eliminated.

Simultaneity of Lightray A striking Target with Lightray B can be established by placing upon Target (A) cameras which take time-stamped photographs of the strikes so close to the strikepoints that light-distance problems are eliminated or (B) electronic strike-sensors whose sensations can be time-stamped and whose engineering is such that light-distance problems are eliminated.

The time-stamping for the stipulated photographs/sensor-reports is to be done by a single clock located midway between the lightray strikepoints whose time-intervals--ITIs--are stipulated to be invariable--ITIs, the clock itself thereby to be an ITIC, to eliminated potential concerns/issues/claims of differences of rates of operation which could be made if two time-stamping clocks were used, and, worse, if their time-intervals were variable, VTIs, and, thus, the clocks were VTICs.

Further, there is another stipulation that there are no gravitational/electromagnetic/etc. physical effects which could potentially change the rate of operation of the time-stamping clock.

These time-stamped photographs/sensor reports eliminate any possible reference frame differences of observation of reflected light from the strikepoints upon Target. The photographs/reports can be examined and analyzed by a scientist upon any reference frame (including the Lightsource<->Target reference frame and the Spaceship reference frame as well any other third reference frame) at any timepoint after they are taken and they are organized and presented to the scientist, thus establishing and focusing upon When? and eliminating potential relativistic confusions of time/When? as well as space/Where?

Any other phenomena not currently imagined but which could potentially distort the perfection of the proposed/stipulated parameters of the gedankenexperiment are to be provided with stipulative restrictions which eliminate their potential for distortions.

[Lobstrosity]

Lightrays A and B are identical for all intents and purposes. The fact that one passes through a spaceship has no bearing on anything. Lightray B isn't suddenly in the frame of the spaceship while Lightray A remains in the frame of the external observer simply because B passes through the spaceship and A doesn't. This thought experiment is conveys nothing and is the epitome of trivial. It's isomorphic with the following thought experiment:

You fire two lightrays at a target. The two lightrays are fired at the exact same time from very nearly the same point in space along parallel paths. You then observe that the two hit the target at the same time. It's amazing!

Why won't you realize that the addition of the "spaceship" would have no physical effect (even according to the theory of relativity) beyond the potential for refraction?

[spacer1]

Bob K,

I have to agree with Lobstrosity. Your latest clarification/restatement of your theory doesn't solve any of the problems raised by other posters (especially Jesse). Perhaps you could respond to these criticisms, rather than merely restating your "gedankenexperiment" in a different way.

[ex-xian]

Originally posted by Bob K
Blah blah blah gedankenexperiment. Blah blah blah not refracted. Blah blah blah gedankenexperiment blah blah rays straight blah blah like ruler blah. Gedankenexperiment blah blah cool clock blah. Blah gedankenexperiment blah gedankenexperiment.
Ok, now that that's settled, how about actually responding to what everyone here who has actually taken some physics has told you.

[nermal]

Yes. Next topic.

Ed

[Jesse]

Bob, regarding your arguments about time-stamped photos taken arbitrarily close to each event, that is exactly what the idea of a "coordinate system" for each reference frame is based on. Imagine the following addition to the numerical example I gave in my last post:

--Two very long rulers placed very close to the axis along which the lightsource/target, rocket, and bottom light beam are.
--One ruler is at rest relative to the lightsource/target, the other at rest relative to the rocket (so the two rulers are moving at 0.5c relative to one another).
--Each ruler has markings that will appear to be the correct size relative to an observer at rest relative to that ruler (but the other ruler's markings will appear too small).
--Each ruler has a series of clocks at each marking. The clocks appear to tick at the correct rate relative to an observer at rest relative to that ruler (though the other ruler's clocks will appear to tick slower). The clocks are also synchronized in the ruler's rest frame--for an observer at rest relative to the ruler, the image of a clock 1 light-second (300,000 km) away will be 1 second behind the clock he's next to, so he can see the two clocks are "really" synchronized in his frame (but if he looks at the other ruler which is moving relative to him, the clocks along that one won't appear synchronized to him, although they'll be synchronized to someone at rest relative to the other ruler).
--There are cameras next to each clock/marking which take pictures of events that happen close to them.
--At the point in space and time where the bottom beam is emitted, cameras at the point on the rulers arbitrarily close to this event show that it happens next to both ruler's "0 meters" mark, and clocks on both these marks read "0 microseconds".

Given all these conditions, the x-coordinate and t-coordinate in both frames that I gave earlier will correspond to what the cameras showed was the position-marking and time-reading of one of the two rulers right next to the event described. For the ruler at rest relative to the lightsource/target, the following readings will be seen in pictures taken right next to these events:

Bottom beam emitted:
0 m, 0 µs
Bottom beam passes back of rocket:
400 m, 1.333 µs
Bottom beam passes front of rocket:
417.3 m, 1.391 µs
Bottom beam hits target:
500 m, 1.667 µs

And here would be the what the pictures would show for the readings on the second ruler, which is at rest relative to the rocket, right next to the events:

Bottom beam emitted:
0 m, 0 µs
Bottom beam passes back of rocket:
230.9 m, 0.770 µs
Bottom beam passes front of rocket:
240.9 m, 0.803 µs
Bottom beam hits target:
288.6 m, 0.962 µs

(if you wanted to have y-coordinate measurements too, and measurements made arbitrarily close to the top beam as well as the bottom beam, you could have two 2-D grids of rulers rather than just two rulers along a single axis--you would get the same measurements as the coordinates I gave in my last post for the top beam's emission and hitting the target, showing that the top beam hits at the same time as the bottom one in both frames)

So, you can see that the idea of each reference frame having its own "coordinate system" is based on the readings you'd get if you layed a real physical grid of rulers and clocks throughout space, at rest in that reference frame.

[wiploc]

Originally posted by Bob K
So, place your bets--when does Lightray B strike Target?

Yes, I have an answer, and part of the answer involves a statement which is true: The speed of light is the same for all observers.

More later.

You talk like light has an actual speed. What it has is a speed apparent to an observer. The beam of light doesn't change speed near the spaceship. It always seems to go one speed to the observer back on earth, and it always seems to go another speed to the observer in the spaceship.

I'm going to to render your example again, using small numbers, since I am mathematically trained to be able to deal with numbers you can hold in one hand:

Joe, back in the Kansas City train station, splits a beam of light and sends it toward Topeka. Joe sees the light traveling at 10 miles an hour (as I said, I like small numbers). Joe knows that it is Noon, and that Topeka is ten miles away, so he knows the light will reach Topeka at one o'clock.

Sara is halfway to Topeka, riding towards Topeka, in a train car going eight miles per hour (relative to the speed of Joe, Kansas City, and Topeka). She sees the light as going 10 miles per hour relative to her, because light does that; its speed looks the same to everybody. We'll simplify our life by saying she doesn't notice when the light leaves KC, and doesn't know what time it is when the light passes her, so she bases her calculations on Joe having told her that he was firing the light at noon. She reasons thusly: "I'm going eight miles an hour. The light is going ten miles an hour faster than me, so that means it's going eighteen miles an hour. So the transit time of the light will be 33.33 minutes. The light will reach Topeka just after 12:33."

Joe will see both beams of light reach Topeka as traveling at the same speed, and both reaching Topeka at the same time. Sara will also see them as traveling the same speed and reaching Topeka at the same time. But Sara will see them as reaching Topeka before Joe does.

Neither viewpoint is privileged. It isn't like one of them is right and the other wrong.

This is not to say someone couldn't be wrong; if you believed that one beam reached Topeka at a different time than the other, you would be wrong.

crc

[jfryejr]

Originally posted by Bob K
The conclusions of this gedankenexperiment are the same for General Relativity conditions wherein one reference frame is accelerating and/or rotating and thus not traveling in uniform/constant velocity/motion relative to another reference frame (providing that Lightray B enters a rear window of Spaceship and exits a front window).If you considered General Theory before posting this, you would have considered red shift with an accelerating reference frame...indicating different wavelengths being measured from the ship. GT agrees with time dilation and c as a constant, only instead of velocity, it considers gravity (or acceleration).

Why do I feel like I posted this same response twice...?

[ShaneC]

Originally posted by Lobstrosity
Lightrays A and B are identical for all intents and purposes. The fact that one passes through a spaceship has no bearing on anything. Lightray B isn't suddenly in the frame of the spaceship while Lightray A remains in the frame of the external observer simply because B passes through the spaceship and A doesn't. This thought experiment is conveys nothing and is the epitome of trivial. It's isomorphic with the following thought experiment:

You fire two lightrays at a target. The two lightrays are fired at the exact same time from very nearly the same point in space along parallel paths. You then observe that the two hit the target at the same time. It's amazing!

Why won't you realize that the addition of the "spaceship" would have no physical effect (even according to the theory of relativity) beyond the potential for refraction?

Hello,

I'm new to this forum and this is my first post here. I know this is an old thread, but wanted to add a twist to some of BobK's gedankenexperiment. Reading his posts, I can see why, he would think there might be an increase in the velocity of light, as it passed through the windows of the spaceship.
Now if the inside of the spaceship was filled with air, and noting that you have already acknowledged that refraction, would have an affect on the passing beam of light, there is some physical evidence, that suggests that the beam B, might actually reach the target before beam A. From the very book, that BobK has already referenced, in earlier posts;

(See chapter 13, of Relativity, The Special and the General Theory, by Einstein. 1920)

Fifty years before Relativity, Armand Fizeau measured the speed of light, through a liquid. He then set the liquid in motion and measured the speed of light again.
Fizeau found W = w + v(1 - 1/n²)

C is the velocity of light in a vacuum.
w is the velocity of light in the liquid.
n = C/w, which is the index of refraction of the liquid medium.
v is the velocity of the moving liquid.
W is the velocity of light, relative to the observer, who is at rest relative to the moving liquid.

This finding was also confirmed, in the early part of the 20th century, by the Dutch physicist and Nobel laureate Pieter Zeeman.

Here is an example of the experiment, applying the math to water moving at a velocity of 300 miles per hour.

W = w + v(1 - 1/n²)

C = 186,000 miles per second (Speed of light in a vacuum)
w = 139,850 miles per second (Speed of light, through static water)
w = 503,460,000 miles per hour (Speed of light, through static water)

n = C/w (Index of refraction of water)
n = 1.33

Velocity of the water flowing through the tube.
v = 300 miles per hour

(1 - 1/n²) = 0.434676917858556164848210752446

300(1 - 1/n²) = 130.4030753575668494544632257338 miles per hour.
w + 130.4030753575668494544632257338 = W.
W = 503460130.40307535756684945446323 miles per hour.

The velocity of light increased, 130.4030753575668494544632257338 miles per hour,
in the direction of the flowing water, relative to the observer, who is at rest relative to the moving water.

Now if we were to apply the Fizeau experiment to BobK's gedankenexperiment, where the spaceship represents the flowing water, relative to the observer at rest, we do get some interesting results.

C = 186,000 m/s
n = C/w, which is the index of refraction
n = 1.0003 (the index of refraction for air)
w = 185944.216734979506148155553334 m/s (speed of light in air)
v = 93,000 m/s (velocity of the rocket relative to the source of light and the observer)
(1 - 1/n²) = 0.00059973010795951457489874901 x 93000 =
55.77490004023485546558365793 miles per second, increase, in the velocity of ligh.

Now if this is correct, then it is possible for the spaceship to boost the velocity of beam B, therefore beam B, could actually reach the target, before beam A. Of course this goes against Einstein's special theory of relativity.

Shane

[Jesse]

Originally posted by ShaneC
Now if this is correct, then it is possible for the spaceship to boost the velocity of beam B, therefore beam B, could actually reach the target, before beam A. Of course this goes against Einstein's special theory of relativity. No, it doesn't go against the special theory of relativity. The "c" in the equations of relativity refers only to the speed of light in a vacuum, but relativity certainly doesn't say that light can't slow down when passing through a medium. However, Bob K did not say anything about the ship being fluid-filled in his post--I was just imagining the ship as something like a hollow empty tube.

[aychamo]

Ok, my question..

Why does time slow down when you approach speeds near c (eg, .9c)?

[aychamo]

Ok, my question..

Why does time slow down when you approach speeds near c (eg, .9c)?

[ShaneC]

Originally posted by Jesse
No, it doesn't go against the special theory of relativity. The "c" in the equations of relativity refers only to the speed of light in a vacuum, but relativity certainly doesn't say that light can't slow down when passing through a medium. However, Bob K did not say anything about the ship being fluid-filled in his post--I was just imagining the ship as something like a hollow empty tube.

Hi Jesse,

I should have paid closer attention to my own math. Even after applying the Fizeau equation, the velocity of light, relative to the observer, was still slightly under C.

55.77490004023485546558365793 miles per second, increase, in the velocity of light,
added to the velocity of light in air;
185944.216734979506148155553334 m/s (speed of light in air)
equals 185999.99163501974100362113699193 miles per second.

[ShaneC]

Originally posted by aychamo
Ok, my question..

Why does time slow down when you approach speeds near c (eg, .9c)?


I was waiting for Jesse to answer this question, but I'll take first shot at this one.

You don't have to be going super fast, for time dilation to happen. Time is always speeding up and slowing down, as you go about your daily life. Rushing to the store in your car, actually has relativistic effects. It's just that these effects are so small, that they are almost undetectable. Here is an example, of the relativistic effects, when you fly accross country in a Jet.

Time dialation, is calculated by the gamma factor, which is 1, divided by the square root of 1 - v²/C²

At 300 miles per hour, time is slowed down by gamma
C equals 186,000 miles per second or 669,600,000 mile per hour
Gamma equals 1.0000000000001003648462892457208

Due to the gamma effects of time dilation, for every second that passes, for you, 1.0000000000001003648462892457208 seconds passes for that person who is waiting to greet you at the airport.

Now if you were on a futuristic highspeed space ship, traveling at .865 the speed of light, relative to the earth, then for every second that passed for you, two seconds would pass for us here on earth.

I don't think this answered your question, of why time slows down. The how's and why's, of specail relativity are compex and subject to debate, but there is a great deal of physical evidence supporting the reality of time dilation.

Shane


Religion, like a drug, is an escape from reality and like a drug can be addictive. Just say no to God.

[aychamo]

Right, that did not answer why time slows down. I do not doubt that the reason why it slows down is very complicated. But, that did give me an explanation that I can get a grasp on with what I presume to be the very basics of SR, thank you for that.

For example, my dad and I are flying to Nicaragua on the 3rd of January. It's about a two hour plane flight, so that is four hours total.

Lets say the plane is traveling at 300mph, like in your example.

4 hrs * 60 mins/hr * 60 sec/min = 14,400 seconds

So when I am back in my house, my dad and I will have "aged" 14,400 seconds, but my mother will have aged:

14,400 * 1.0000000000001003648462892457208 seconds ??

So at the very low fraction of c, the age discrepancy will be so low that it is basically negligible. But at the high fraction, like you said .865c, my mom would have aged 8 hours while me and my dad only aged 4 hours?

How does this fit in with the twins paradox thing? Like, from my moms point of view would me and my dad have aged 8 hours while she only aged 4 (if our Continental airplane flew at .865c(!!))?

Thank you

[Tetlepanquetzatzin]

Originally posted by aychamo
Right, that did not answer why time slows down. I do not doubt that the reason why it slows down is very complicated. But, that did give me an explanation that I can get a grasp on with what I presume to be the very basics of SR, thank you for that.
There is no explanation for time dilation. Imagine that you live in 19:th century and have never heard of SR. You, like all other learned individuals, believe that all observers will see the same spatial and time distances between events. What would this 19:th century version of you answer if asked why there's no time dilation?

Today we know that the length of a time interval depends on relative velocities and that objects experiencing acceleration or gravitation age more slowly. But we cannot explain this fact anymore than physicists in the pre-relativistic era could genuinely explain why time is absolute.
For example, my dad and I are flying to Nicaragua on the 3rd of January. It's about a two hour plane flight, so that is four hours total.

Lets say the plane is traveling at 300mph, like in your example.

4 hrs * 60 mins/hr * 60 sec/min = 14,400 seconds

So when I am back in my house, my dad and I will have "aged" 14,400 seconds, but my mother will have aged:

14,400 * 1.0000000000001003648462892457208 seconds ??
Yes, that's qualitatively correct. I haven't checked if the actual numbers are correct (they are guaranteed to be incorrect if you used the ordinary equation for time dilation -- they are correct if you integrated small distance intervals).
So at the very low fraction of c, the age discrepancy will be so low that it is basically negligible. But at the high fraction, like you said .865c, my mom would have aged 8 hours while me and my dad only aged 4 hours?

How does this fit in with the twins paradox thing? Like, from my moms point of view would me and my dad have aged 8 hours while she only aged 4 (if our Continental airplane flew at .865c(!!))?
The resolution of the twin paradox is that acceleration and gravitation make things age more slowly.

[aychamo]

Hey, thank you for your post. The explanations you guys are giving me are perfect. I know for yall they are dumbed down, but for me they are right outside of the realm of my knowledge on this information, which is really letting me understand this better than I previously did(n't.)

I guess with my last question, I meant to ask, since my dad and I are on the plane, we will have aged the four hours, and my mom back at home would have aged four hours * the additional time.

But to my mom, since she stayed "stationary" and we flew off, would she have aged four hours, and my dad and I aged the greater time?

[Tetlepanquetzatzin]

Originally posted by aychamo
Hey, thank you for your post. The explanations you guys are giving me are perfect. I know for yall they are dumbed down, but for me they are right outside of the realm of my knowledge on this information, which is really letting me understand this better than I previously did(n't.)

I guess with my last question, I meant to ask, since my dad and I are on the plane, we will have aged the four hours, and my mom back at home would have aged four hours * the additional time.

But to my mom, since she stayed "stationary" and we flew off, would she have aged four hours, and my dad and I aged the greater time?
If you took really accurate clocks with you on the trip and left another really accurate clock at home with your mom, then all three of you would agree that your mom had aged the most.

The slowing of time due to acceleration and gravitation is not symmetric, unlike time dilation.

[Bob K]

The real reason why clocks slow down, their rates of operation are less, and organisms appear to not age as much when accelerated as when not accelerated is the increase in inertial mass due to acceleration causes the internal stuffs of machines/organisms to move slower.

Think of swinging a ball around in a circle by a tether.

The faster you swing it/the more you accelerate it, the 'heavier' the ball seems, which is a subjective experience of the increase in the inertial mass of the accelerated ball; and the slower you swing it, the 'lighter' the ball seems, which is a subjective experience of the decrease in the inertial mass of the decelerated ball.

When a machine's/organism's inertial mass increases, all of its parts are more resistant to changes of motion/direction, and with no increase in the internal energy used to create the motions of the parts, there will be a subsequent and therefore consequent slowing of the motions of the parts.

With a slowing of the motions of the parts of a machine/organism due to increases in inertial mass due to increases in acceleration, the rate of operation of a machine or an organism is lower, and therefore slower, than non-accelerated similar machines/organisms, clocks will count less time-intervals/have lower face-readings and hence time will appear to be dilated (slowed down), and organisms will appear to age less; with a speeding up of the motions of the parts of a machine/organism due to decreases in inertial mass due to decreases in acceleration/due to deceleration, the rate of operation of a machine or an organism is higher, and therefore faster, than non-decelerated similar machines/organisms, clocks will count more time-intervals/have higher face-readings and hence time will appear to be dilated (speeded up), and organisms will appear to age more.

[aychamo]

Originally posted by Tetlepanquetzatzin
If you took really accurate clocks with you on the trip and left another really accurate clock at home with your mom, then all three of you would agree that your mom had aged the most.

The slowing of time due to acceleration and gravitation is not symmetric, unlike time dilation.

Ahh, so it's the one that moves. So the things with the twins paradox, the "problem" was that they assumed either one would age depending on the frame of reference?

[Jesse]

Originally posted by aychamo
Ahh, so it's the one that moves. So the things with the twins paradox, the "problem" was that they assumed either one would age depending on the frame of reference? It's not the one that moves, it's the one that accelerates. If both move away from each other at constant velocities, each will observe the other to age more slowly, and there is no experiment that can be done to determine which one is "really" moving or which one is "really" aging more slowly. But if one accelerates in order to turn around and meet up with the other so they can compare clocks, the one who accelerated will be found to have aged less. So, if one twin heads out in a rocket and then turns around and returns to earth, he'll have aged less than the twin who stayed on earth; on the other hand, if one twin headed out in a rocket at constant velocity and then the other twin strapped huge rockets to the earth and used them to catch up with the one on the rocket, the earth-twin will have aged less.

The "paradox" comes from mistakenly thinking relativity says all motion is relative, and that each observer is justified in treating himself as being at rest while the other is moving. The resolution is that relativity actually only says this about inertial (non-accelerating) observers, an observer who accelerates cannot treat himself as being at rest while everyone else moves around him (at least not in 'special' relativity--in general relativity even accelerating observers may be able to treat themselves as being at rest, but I'm not sure how it works, it might require them to assume a non-flat spacetime).

[Jesse]

Bob K:
The real reason why clocks slow down, their rates of operation are less, and organisms appear to not age as much when accelerated as when not accelerated is the increase in inertial mass due to acceleration causes the internal stuffs of machines/organisms to move slower.

Think of swinging a ball around in a circle by a tether.

The faster you swing it/the more you accelerate it, the 'heavier' the ball seems, which is a subjective experience of the increase in the inertial mass of the accelerated ball; and the slower you swing it, the 'lighter' the ball seems, which is a subjective experience of the decrease in the inertial mass of the decelerated ball.

This phenomenon has nothing to do with the relativistic slowing of clocks; for example, if you attached a clock to the tether ball, you would not notice it ticking slower when you were swinging it more slowly (assuming that in both cases you're swinging it at a negligible fraction of light speed).

Bob K:
When a machine's/organism's inertial mass increases, all of its parts are more resistant to changes of motion/direction, and with no increase in the internal energy used to create the motions of the parts, there will be a subsequent and therefore consequent slowing of the motions of the parts.

With a slowing of the motions of the parts of a machine/organism due to increases in inertial mass due to increases in acceleration, the rate of operation of a machine or an organism is lower, and therefore slower, than non-accelerated similar machines/organisms, clocks will count less time-intervals/have lower face-readings and hence time will appear to be dilated (slowed down), and organisms will appear to age less; with a speeding up of the motions of the parts of a machine/organism due to decreases in inertial mass due to decreases in acceleration/due to deceleration, the rate of operation of a machine or an organism is higher, and therefore faster, than non-decelerated similar machines/organisms, clocks will count more time-intervals/have higher face-readings and hence time will appear to be dilated (speeded up), and organisms will appear to age more.

As I have already pointed out to you elsewhere, when two observers are moving at a constant velocity relative to one another, they cannot agree on the ratio between the ticks of their respective clocks; each one thinks their own clocks are running at the normal rate while the other's clocks are running slow. In a similar way, they cannot agree on which observer's mass is "really" increasing--each will observe their own mass remaining the same while the other's mass appears to have increased. What experiment do you propose to do to see which of two observer's mass has "objectively" increased in a manner that is independent of your reference frame?

[Bob K]

Jesse

Part One

Bob K:The real reason why clocks slow down, their rates of operation are less, and organisms appear to not age as much when accelerated as when not accelerated is the increase in inertial mass due to acceleration causes the internal stuffs of machines/organisms to move slower.

Think of swinging a ball around in a circle by a tether.

The faster you swing it/the more you accelerate it, the 'heavier' the ball seems, which is a subjective experience of the increase in the inertial mass of the accelerated ball; and the slower you swing it, the 'lighter' the ball seems, which is a subjective experience of the decrease in the inertial mass of the decelerated ball.

Jesse:This phenomenon has nothing to do with the relativistic slowing of clocks; for example, if you attached a clock to the tether ball, you would not notice it ticking slower when you were swinging it more slowly (assuming that in both cases you're swinging it at a negligible fraction of light speed).

This phenomenon was mentioned by Albert E--he described it in reference to a rotating disc wherein a clock at the center would not slow down compared to a clock on the edge, which, when compared to the clock in the center, would slow down.

This is not a visual phenomenon--it is an inertial phenomenon, a phenomenon resulting from the phenomenon of acceleration, and the rotating clock on the edge of the rotating disc is by physical necessity at some timepoint accelerated to attain the speed difference between itself and the center clock.

The rotating ball on a tether is similar to a rotating clock on a disc. Clearly, and obviously, to rotate a ball on a tether about your head you must accelerate the ball, thus you must increase its inertial mass, exactly as I have described.

Similarly, when a clock is located on the edge of a rotating disk, and some timepoint it was accelerated, and, once accelerated, it's inertial mass is increased. And when the rotating clock's inertial mass is increased its parts are 'heavier' and more resistant to movement when the same energy/force is applied, hence the rates of operation of rotating and therefore accelerated clocks will slow down, and the duration of their time-intervals will increase, and their time-measurements and therefore their face-readings will be less than a non-accelerated clock at the center of a rotating disk..

And when a rotating clock is decelerated, its inertial mass will decrease, its parts will be 'lighter,' its rate of operation will increase compared to when it was accelerated, its time-interval duration will decrease, and its face-reading/time-measurement/time-interval count will increase.

No mysteries herein.

The change of reference frames is no explanation for the cause of variations in observable phenomena.

For every cause there is an effect, so for the effect of a variation of observations in different reference frames there has to be a physical phenomenon which is a cause/one-cause-among-many-causes if not the one-and-only cause.

One of the explanations for the cause of time-dilation in clocks whose mechanisms are not motion-sensing/self-adjusted or/and synchronized by radio signals from master clocks is for accelerated clocks the decrease of rates of operation and the increase of time-interval durations and the decrease in face-readings (compared to non-accelerated similar clocks) caused by increases in inertial mass due to acceleration and for decelerated clocks the increase of rates of operation and the decrease in time-interval duration and the increase in face-readings (compared to non-decelerated similar clocks) caused by decreases in inertial mass due to deceleration.

[Bob K]

Jesse

Part Two

Bob K:When a machine's/organism's inertial mass increases, all of its parts are more resistant to changes of motion/direction, and with no increase in the internal energy used to create the motions of the parts, there will be a subsequent and therefore consequent slowing of the motions of the parts.

With a slowing of the motions of the parts of a machine/organism due to increases in inertial mass due to increases in acceleration, the rate of operation of a machine or an organism is lower, and therefore slower, than non-accelerated similar machines/organisms, clocks will count less time-intervals/have lower face-readings and hence time will appear to be dilated (slowed down), and organisms will appear to age less; with a speeding up of the motions of the parts of a machine/organism due to decreases in inertial mass due to decreases in acceleration/due to deceleration, the rate of operation of a machine or an organism is higher, and therefore faster, than non-decelerated similar machines/organisms, clocks will count more time-intervals/have higher face-readings and hence time will appear to be dilated (speeded up), and organisms will appear to age more.

Jesse:As I have already pointed out to you elsewhere, when two observers are moving at a constant velocity relative to one another, they cannot agree on the ratio between the ticks of their respective clocks; each one thinks their own clocks are running at the normal rate while the other's clocks are running slow. In a similar way, they cannot agree on which observer's mass is "really" increasing--each will observe their own mass remaining the same while the other's mass appears to have increased. What experiment do you propose to do to see which of two observer's mass has "objectively" increased in a manner that is independent of your reference frame?

Do we have means of determining if or not an air-borne or a space-borne clock is accelerated relative to a similar Earth-bound clock?

What happens when an aircraft is sent aloft into the Earth's atmosphere or a spacecraft is sent into space? The aircraft or spacecraft is obviously accelerated, and any air-borne or space-borne clocks are therefore accelerated. Acceleration of objects sent into the Earth's atmosphere or into space is not conjecture, it is a requirement of sending stuff into the Earth's atmosphere or into space.

In the case where two objects are moving relative to each other, if one has been accelerated and the other has not, then the accelerated object has an increase in its inertial mass.

I am preparing an exposition of how to synchronize and check for synchronization of invariable time-interval clocks (ITICs), but I will share with you now one set of facts which will establish a standard for the determination of the synchronization of ITICs.

Einstein, in his book, Relativity, used an example of a railway embankment (RE) as one reference frame/coordinate system, K and a railway carriage (RC) as another reference frame/coordinate system, K' (when the RC/K' reference frame/coordinate system was moving relative to the RE/K reference frame/coordinate system), and he specifically stated that when moving relative to the RE/K reference frame, the RC/K' was a different reference frame.

In the following discussion,

(A) The RE/K Reference Frame = The Earth/K Reference Frame
... and ...
(B) The RC/K' Reference Frame = The Jet Aircraft/K' Reference Frame.

To verify SR/GR time-dilation, caesium-atom clocks--atomic clocks--were constructed of similar design, activated/started simultaneously, on the Earth, therefore in the Earth's reference frame, K, and some were loaded aboard a jet aircraft and sent aloft, accelerated to cruising speed of 500-600 mph, which was maintained for a number of hours, during which the air-borne clocks were in another reference frame, K', and then those air-borne clocks were returned to Earth, and their face-readings/time-measurements were compared to each other and to the face-readings of the Earth-bound clocks, and the standard for the determination/confirmation/verification of time-dilation was a difference between the average face-reading of the air-borne clocks and the average face-reading of the Earth-bound clocks, and, upon a finding of a difference of face-readings between air-borne and Earth-bound atomic clocks of similar design/construction and simultaneous activation (simultaneous startup), scientists declared the theory/hypothesis of time-dilation had been proven/confirmed/verified.

Here we have a simple set of facts:

(1) Clocks of similar construction and activated simultaneously in one reference frame/coordinate system, K.
(2) One set of clocks was accelerated, thus entering into a different reference frame/coordinate system, K'.
(3) The accelerated clocks were returned to the originating reference frame/coordinate system, K.
(4) The face-readings of the accelerated clocks were compared to the face-readings of non-accelerated clocks.
(5) The standard for the proof/confirmation/verification/falsification/denial/etc. of time-dilation was a difference between the accelerated clocks' face-readings/time-measurement (a lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurements.
(6) A difference between the accelerated clocks' face-readings/time-measurement (a lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurements was observed.
(7) Time-dilation was proved/confirmed/verified.

Focus on the fact that there were no confusions of different observers on different reference frames arguing over whose observations and interpretations were correct; the same reference frame was used for comparing the face-readings of accelerated clocks v the face-readings of non-accelerated clocks.

Focus on the fact that there was a difference between the face-readings of accelerated clocks v non-accelerated clocks.

This difference could be expressed as a ratio of the rate of operation or time-interval of the accelerated clocks v the rate of operation or time-interval of the non-accelerated clocks once a difference between the rate of operation of the accelerated clocks and the rate of operation of the non-accelerated clocks was established by means of the observation of a difference, e.g. the lower face-readings/time-measurements/rate of operation of the accelerated clocks compared to the face-readings/time-measurements/rate of operation of the non-accelerated clocks.

Focus on the standard for the confirmation/verification of time-dilation, which was the observation of a difference of face-readings between the accelerated clocks and the non-accelerated clocks.

This standard for the confirmation/verification of time-dilation can be applied for a confirmation/verification of non-time-dilation.

Here is an experiment which could verify/falsify non-time-dilation:

(1) Clocks of similar construction are to be activated simultaneously in one reference frame/coordinate system, K.
(2) One set of clocks to be accelerated, thus entering into a different reference frame/coordinate system, K'.
(3) The accelerated clocks are to be returned to the originating reference frame/coordinate system, K.
(4) The face-readings of the accelerated clocks are to be compared to the face-readings of non-accelerated clocks.
(5) The standard for the proof/confirmation/verification/falsification/denial/etc. of non-time-dilation is to be no difference between the accelerated clocks' face-readings/time-measurement (no lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurements.
(6) Prediction: If no difference between the accelerated clocks' face-readings/time-measurement (a lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurements is observed, ...
... then ...
(7) Conclusion: Non-Time-dilation is proved/confirmed/verified.

Therefore:

(1) Construct similar atomic clocks, by
(A) Design A: Motion-Sensing/Self-Adjusting,
(B) Design B: Synchronized by Radio Signals from a Master Clock on Earth,
(C) Design C: Motion-Sensing/Self-Adjusting and Synchronized by Radio Signals from a Master Clock on Earth;
(2) Activate the clocks simultaneously in the Earth's reference frame, K;
(3) Send/accelerate a group of clocks into the air aboard a jet aircraft to a cruising speed of 500-600 mph for several hours in the aircraft's reference frame, K';
(4) Return the air-borne clocks to the Earth/to the Earth's reference frame, K;
(5) Compare/observe the accelerated air-borne clocks' face-readings/time-measurements with the non-accelerated Earth-bound clocks' face-readings/time-measurements;
(6) The standard for the proof/confirmation/verification/falsification/denial/etc. of non-time-dilation is to be no difference between the accelerated clocks' face-readings/time-measurement (no lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurement;
(7) An observation of no difference between the accelerated clocks' face-readings/time-measurement (no lesser/lower face-reading/time-measurement) and the non-accelerated clocks' face-readings/time-measurement is to be proof of non-time-dilation.

Prediction: #7 will produce observations of identical face-readings of accelerated and non-accelerated clocks and confirmation/verification of non-time-dilation.

#7, the identical face-readings of the air-borne accelerated clocks when compared to each other, will also be proof of the synchronization of the air-borne/accelerated clocks with each other, and an observation of the identical face-readings of the air-borne/accelerated clocks with the Earth-bound/non-accelerated clocks will also be proof of the synchronization of the air-borne clocks with the Earth-bound clocks.

#7 will also be confirmation/verification of the net effect of no change of rate of operation for both the air-borne/accelerated clocks and the Earth-bound/non-accelerated clocks, and, thus, #7 will also be confirmation/verification of the theory of invariable time-intervals, and of how invariable time-intervals disconfirm time-dilation and thereby and therefore establish non-time-dilation for accelerated clocks and thereby and therefore establish universal/absolute time, and thereby and therefore establish the independence of space and time, and the destruction of the concept of spacetime.

Focus on the fact that no observers in different reference frames are available to argue over whose clocks were/were not accelerated because the same observers and the same reference frame--the Earth's reference frame, K, are to be used for the construction and activation of the clocks and the final observation of the clocks' face-readings and the application of the standard for time-dilation/non-time-dilation and synchronization and the verification/falsification of time-dilation/non-time-dilation and universal/absolute time.

E.g. the Earth-bound observers in the Earth's reference frame, K, in the original time-dilation experiment did not care about the synchronization of the accelerated air-borne atomic clocks while those clocks were in the jet aircraft's reference frame, K'; all they cared about was whether or not the accelerated air-borne clocks' face-readings were identical to each other when those clocks were returned to the Earth/to the Earth's reference frame, K, so their face-readings could be compared to the non-accelerated Earth-bound clocks, which never left the Earth's reference frame, K.

The standard for synchronicity of the accelerated air-borne clocks while accelerated and in the aircraft's reference frame, K', was their identical face-readings when returned to Earth/to the Earth's reference frame, K.

And when the accelerated air-borne clocks' face-readings were determined by observation to be identical, the accelerated air-borne clocks' synchronicity while airborne in reference frame K' was assumed to be a fact.

By extension/extrapolation, if clocks are accelerated by being sent into space, and, therefore, being sent from the originating Earth reference frame, K, into different reference frames, K', K'', K''', etc., and they are returned to Earth, then observations in the Earth's reference frame, K, of the accelerated space-borne clocks' identical face-readings shall be the standard for, and therefore proof/verification of, the synchronicity of the accelerated space-borne clocks while in different reference frames, and an observation of identical accelerated space-borne clocks' face-readings with non-accelerated Earth-bound clocks' face-readings shall be proof/verification of the synchronicity of the Earth-bound and space-borne clocks, and also non-time-dilation, and the theory of invariable time-intervals, and of universal/absolute time.

Similarly, if alien space-borne clocks are brought to Earth/to the Earth's reference frame, and while in the Earth's reference frame are non-accelerated, they can be examined to determine their rate of operation and therefore their time-interval duration, and their rate of operation/time-interval duration can be compared to human non-accelerated Earth-bound clocks to determine the ratio of the alien-clocks' rate of operation/time-interval duration to the human-clocks' rate of operation/time-interval duration, and a common timemap can be created in which the timepoints for the alien-clocks and the human-clocks can be coordinated into coincidental common timepoints; and once coordinated coincidental common timepoints can be established for a common timemap, then events which occurred at/during the same common timepoint will be simultaneous to both aliens and humans.

Focus on the use of the same reference frame for comparison of the rates of operation/time-interval duration of alien-clocks and human-clocks, and the reasoning for the establishment of a common timemap and coordinated coincidental and therefore common timepoints and simultaneity when events are observed to have occurred at the same common timepoints should be obvious and therefore clear.

Moreover, if the alien-clocks were sent/accelerated into different reference frames but when brought to Earth are observed to have identical face-readings with each other, then their synchronicity while in different reference frames can be assumed to be a fact, and any time-stamped photographs of different events sharing identical time-stamps and therefore identical time-stamps at common timepoints on their common timemap would be proof of the simultaneity of the events' occurrences as observed by the aliens' clocks, and time-stamps at common timepoints on the common timemap for the alien-clocks and human-clocks would show simultaneity of events observed by aliens' clocks with events observed by humans' clocks.

By the restriction of the use of alien-clocks and human-clocks instead of a-observers or h-observers for the observation of different events, problems with observers in different reference frames arguing with each other over whose observations are 'true' and therefore 'accurate' are eliminated if the alien-clocks are observed to have identical face-readings when brought to Earth and therefore observed in the Earth's reference frame. Biological observers--organisms--may have non-identical genetics and therefore may not have the similar rates of operation needed for determining if or not they were synchronized in space by observations of their aging when brought to Earth, therefore their reports of their observations of the occurrences of events in different reference frames would not be expected to be reliable. Alien-clocks can be constructed using similar construction, and human-clocks could be constructed using similar construction, giving us a basis of similar construction which would be needed for establishing synchronicity by observation of face-readings when brought to Earth.

The choice of the Earth's reference frame, K, for the return of accelerated clocks and the observation of their face-readings v the face-readings of non-accelerated clocks is an arbitrary choice, but because the same validity of the choice of another reference frame, such as that of the moon, or, Mars, would also be arbitrary but would produce the same results provided the clocks are assembled and activated simultaneously within that reference frame and accelerated clocks are returned to the same reference frame for comparison of their face-readings with the face-readings of non-accelerated clocks, the arbitrariness of the choice of originating reference frame is non-essential and therefore irrelevant.

I have given an example of how time-dilation was established by an experiment using clocks of similar construction and simultaneous activation for which the standard for time-dilation and therefore non-synchronicity was the difference of the face-readings of accelerated clocks when compared to the face-readings of non-accelerated clocks when the accelerated clocks were returned to the same reference frame in which the non-accelerated similar clocks are located (these clocks were of varying rates of operation and therefore variable time-intervals and were therefore variable time-interval clocks--VTICs).

I have given an example of how non-time-dilation can be established by an experiment using clocks of similar construction (by Designs A, B or C for identical rates of operation/invariable time-intervals for invariable time-interval clocks--ITICs) and simultaneous activation for which the standard of non-time-dilation and therefore synchronicity will be no difference between the face-readings of accelerated clocks and the face-readings of non-accelerated clocks, and I have given a prediction that when clocks of similar construction by Designs A, B or C and activated simultaneously in one reference frame are accelerated and they are returned to the same reference frame in which the non-accelerated similar clocks are located then the face-readings of the accelerated clocks will be similar to each other and to the non-accelerated similar clocks.

I fully expect that for Design B ITICs we can monitor the position and therefore the location of the accelerated B-ITICs and provide a continuous stream of radio signals all essentially saying "When you receive this signal from the master clock here on Earth the synchronized time will be contained in the information transmitted, therefore reset your clock to the synchronized time as given in the transmitted information!" and thus the accelerated air-borne, or space-borne, clocks will be synchronized with the non-accelerated clocks, as will be revealed by observations of identical face-readings of accelerated and non-accelerated clocks when the accelerated clocks are returned to Earth.

Therefore, I expect that the non-time-dilation experiment will not be physically impossible to conduct, and, when conducted, will confirm/verify the theory of invariable time-intervals, the non-dilation of time when invariable time-interval clocks are used, the theory of universal/absolute time, and the independence of time from space.

[ShaneC]

Now aychamo knows what I ment when I said that >
<<The how's and why's, of specail relativity are compex and subject to debate, but there is a great deal of physical evidence supporting the reality of time dilation.>>

Quote from Tetlepanquetzatzin
<<There is no explanation for time dilation. >>

Bob just gave one good explanation. Tetlepanquetzatzin,
Imagine that you live in 19:th century and had never heard of quantum mechanics? Special relativity was founded on pre -quantum physics. Knowledge of the atom, was still in its infancy.

I came to this forum, because I felt Bob was getting close to the reality of special relativity. I am here to try to fill in the gaps.

Jesse and Lobstrosity, have given many excellent examples of special relativity. They know relativity very well. Certainly the physical model of Special Relativity appears to work. It has been tested and retested throughout the 20th century and has been proven to be mathematically sound, but is it the only possible model? Special relativity may appear to be mathematically sound, but if you take a very close look at the concepts of relativity, you will find logical and mathematical problems.

PROBLEM ONE: Moving through space time. (Example)
There are two airplanes traveling at 300 miles per hour, in the direction of each other. Each pilot would consider himself at rest and he would see the other airplane coming at him at 600 m/h. Although relativistic effects are negligible at extremely low velocities, the effects are still present and can be calculated. Apply relativistic calculations, and the pilot in airplane one would calculate the other coordinate systems clock, airplane two, as running slower than his own clock. Turn this around and the pilot in airplane two, would consider himself at rest and airplane one would be coming at him at 600 m/h. Pilot two would also consider himself at rest and after applying relativistic calculations, he also calculates that airplane one's clock, as running slower than his own clock. Throw in a third observer on the ground. The observer on the ground would consider himself at rest, relative to both airplane one and two. The observer, on the ground, sees both airplanes traveling at 300 m/h, relative to himself, and after making relativistic calculations, he concludes that both airplanes' clocks are slowed by the same amount of time, relative to his own time frame. The two observers, one in each airplane, consider himself at rest, relative to the observer on the ground. Applying relativistic calculations, each pilot concludes that the observer, on the ground, is moving at 300 miles per hour, relative to himself and that the clock, on the ground, is running slower than his own clock. All of these observations seem to cancel each other out. Does time really slow down, or is this only a mathematical construction, designed to explain experimental testing, of the speed of light, from different inertial frames of reference?

PROBLEM TWO:
Applying the Lorentz transformations to objects, we discover that, object length and travel distance dilation, only occur in the direction of motion. At right angles to motion, width, thickness and distance remain the same. This produces some logical problems with relativity. If time slows down, by gamma, within the coordinate system as a whole, then the velocity of light would appear to be slower than C, at right angles to the direction of motion, due to the fact that the light has to travel a longer distance, than the light traveling in the direction of motion. If time is only dilated in the direction of motion, then for any object or even living organism in motion, time slows down for only about half of that objects mass, due to relativistic effects. Relativity experts point out that this is why every observer considers himself at rest and the observed coordinate system is in motion relative to the observer. This appears to solve the problem for the observer, but then this same logical problem applies to the remote coordinate system in motion. As the experts try to rationalize the logical problems with relativity, we are still stuck with problem one.

PROBLEM 3:
In the gedankenexperiment, we sent a beam of light to a rocket, traveling at .5C. In order for the observer, (at rest, relative to the rocket), to calculate the time the light will stike the rocket, you must take into account that the rockets velocity, relative to the beam of light, is .5C. If you are the observer on the rocket, you must consider yourself, at rest, relative to the beam of light, and the source of light is receding at .5C. Mathematically, relativity doesn't explain, how the velocity of light, can be the same for different inertial frames of reference. This is merely a necessary restriction, that Einstein placed on special relativity, in order to maintain a constant speed of light, for all observers. He referes to this as the anomaly, of the propagation of light in a vacuum.


In The Demon Haunted World by Carl Sagan, Sagan writes in chapter three, "Each field of science has its own complement of pseudoscience." --- "Physicists have perpetual motion machines, an army of amateur relativity disprovers, and perhaps cold fusion."
I don't think that every relativity disprovers, just doesn't understand relativity. Perhaps many of the relativity disprovers, like Bob and myself, feel strongly, that there is something wrong with the concepts of special relativity, have decided to analyze the theory to figure just what is wrong with it and to formulate a new model of special relativity.

To keep the post short, I will end for now, but will continue in another post latter.

Shane

Religion, like a drug, is an escape from reality and like a drug can be addictive. Just say no to God :D

[ShaneC]

Bob K:

quote:
--------------------------------------------------------------------------------
When a machine's/organism's inertial mass increases, all of its parts are more resistant to changes of motion/direction, and with no increase in the internal energy used to create the motions of the parts, there will be a subsequent and therefore consequent slowing of the motions of the parts.

With a slowing of the motions of the parts of a machine/organism due to increases in inertial mass due to increases in acceleration, the rate of operation of a machine or an organism is lower, and therefore slower, than non-accelerated similar machines/organisms, clocks will count less time-intervals/have lower face-readings and hence time will appear to be dilated (slowed down), and organisms will appear to age less; with a speeding up of the motions of the parts of a machine/organism due to decreases in inertial mass due to decreases in acceleration/due to deceleration, the rate of operation of a machine or an organism is higher, and therefore faster, than non-decelerated similar machines/organisms, clocks will count more time-intervals/have higher face-readings and hence time will appear to be dilated (speeded up), and organisms will appear to age more.
--------------------------------------------------------------------------------

Jesse:
quote:
--------------------------------------------------------------------------------
As I have already pointed out to you elsewhere, when two observers are moving at a constant velocity relative to one another, they cannot agree on the ratio between the ticks of their respective clocks; each one thinks their own clocks are running at the normal rate while the other's clocks are running slow. In a similar way, they cannot agree on which observer's mass is "really" increasing--each will observe their own mass remaining the same while the other's mass appears to have increased. What experiment do you propose to do to see which of two observer's mass has "objectively" increased in a manner that is independent of your reference frame?
--------------------------------------------------------------------------------

Bob has theorized that time dilation, is actually caused by the molecular slowing down of the mass, of an object, as velocity and inertial mass increase. I am going to expand on this thoery, introducing a new term that I call quantum slip, plus I will point out what is wrong with Jesse's statement, "In a similar way, they cannot agree on which observer's mass is "really" increasing--each will observe their own mass remaining the same while the other's mass appears to have increased. "

WHAT ARE THE GAMMA AND BETA FACTORS?

The key to understanding the gamma and beta factors, as well as why time slows down, as velocity increases, is kinetic energy:

(From Encarta Encyclopedia)
<<Kinetic Energy, energy possessed by an object, resulting from the motion of that object. The magnitude of the kinetic energy depends on both the mass and the speed of the object according to the equation,

E = ½mv² or E = m(v²/2)

where m is the mass of the object and v² is its speed multiplied by itself. The value of E can also be derived from the equation,

E = (ma)d

where a is the acceleration applied to the mass, m, and d is the distance through which a acts. The relationships between kinetic and potential energy and among the concepts of force, distance, acceleration, and energy can be illustrated by the lifting and dropping of an object.

When the object is lifted from a surface a vertical force is applied to the object. As this force acts through a distance, energy is transferred to the object. The energy associated with an object held above a surface is termed potential energy. If the object is dropped, the potential energy is converted to kinetic energy. >>

Microsoft® Encarta® Reference Library 2003. © 1993-2002 Microsoft Corporation. All rights reserved.

When a rocket burns fuel to propel itself faster, it is transferring that propellant energy, into kinetic energy. The blast from the rocket causes an acceleration force, which is felt as long as the rocket is accelerating. When the rockets' engine is turned off, the rocket stops accelerating and the acceleration force is no longer felt, but the velocity has changed. Onboard the rocket, the observer feels that he is at rest and is unaware of this increase of kinetic energy, but every atom, within the rocket, is affected by the added kinetic energy.


QUANTUM SLIP AND THE LORENTZ TRANSFORMATIONS:

Special relativity assumes that the speed of, any light source, is constant, as viewed from any inertial frame of reference. Up to now, I have tried to show the problems with this concept. As velocity, kinetic energy and inertial mass increase, the velocity of the electrons orbiting the nucleus slip, (slow down), by the beta factor, but what would cause this slip? Also, if the speed of light is not constant, relative to different inertial frames of reference, then what of the Lorentz transformations?

(From Encarta Encyclopedia)
ELECTRONS AS WAVES:
<<Electrons behave as both particles and waves in atoms. This characteristic is called wave-particle duality. Wave-particle duality actually affects all particles and collections of particles, including protons, neutrons, and atoms themselves. But in terms of the structure of the atom, the wavelike nature of the electron is the most important.

As waves, electrons have wavelengths and frequencies. The wavelength of an electron depends on the electron's energy. Since the energy of electrons is kinetic (energy related to motion), an electron's wavelength depends on how fast it is moving. The more energy an electron has, the shorter its wavelength is. Electron waves can interfere with each other, just as waves along a rope do.

Because of the electron's wave-particle duality, physicists cannot define an electron's exact location in an atom. If the electron were just a particle, measuring its location would be relatively simple. As soon as physicists try to measure its location, however, the electron's wavelike nature becomes apparent, and they cannot pinpoint an exact location. Instead, physicists calculate the probability that the electron is located in a certain place. Adding up all these probabilities, physicists can produce a picture of the electron that resembles a fuzzy cloud around the nucleus. The densest part of this cloud represents the place where the electron is most likely to be located.

Physicists call the region of space an electron occupies in an atom the electron's orbital. Similar orbitals constitute groups called shells. The electrons in the orbital of a particular shell have similar levels of energy. This energy is in the form of both kinetic energy and potential energy. Lower shells are close to the nucleus and higher shells are farther from the nucleus. Electrons occupying orbitals in higher shells generally have more energy than electrons occupying orbitals in lower shells.

The wavelike nature of electrons sets boundaries for their possible locations and determines what shape their orbital, or cloud of probability, will form. Orbitals differ from each other in size, angular momentum, and magnetic properties. In general, angular momentum is the energy an object contains based on how fast the object is revolving, the object's mass, and the object's distance from the axis around which it is revolving. The angular momentum of a whirling ball tied to a string, for example, would be greater if the ball was heavier, the string was longer, or the whirling was faster. In atoms, the angular momentum of an electron orbital depends on the size and shape of the orbital. Orbitals with the same size and shape all have the same angular momentum. Some orbitals, however, can differ in shape but still have the same angular momentum. The magnetic properties of an orbital describe how it would behave in a magnetic field. Magnetic properties also depend on the size and shape of the orbital, as well as on the orbital's orientation in space.

The orbitals in an atom must occur at certain distances from the nucleus to create a stable atom. At these distances, the orbitals allow the electron wave to complete one or more half-wavelengths (y, 1, 1y, 2, 2y, and so on) as it travels around the nucleus. The electron wave can then double back on itself and constructively interfere with itself in a way that reinforces the wave. Any other distance would cause the electron to interfere with its own wave in an unpredictable and unstable way, creating an unstable atom.>>

Microsoft® Encarta® Reference Library 2003. © 1993-2002 Microsoft Corporation. All rights reserved.

Quantum slip, is the result of increased velocity and kinetic energy. The added kinetic energy, velocity and inertial mass affect the angular momentum of the orbiting electrons. Quantum slip is one way the atom naturally maintains stability.

The speed of light propagating through a medium, is influenced by interference from each and every atom that it comes in contact with, the index of refraction, the velocity of the medium and the velocity of the source of light. If there is no medium, such as the vacuum of space, then the speed of light is dependent on the velocity of the source of light. The speed of the light can only propagate as fast as the velocity of the orbiting electrons, within an inertial medium. Under extremely high velocities, in the case of a rocket traveling at .5C, relative to earth, all the atoms, that make up the rocket and the medium within the rocket, are moving at half the speed of the electrons themselves. What physical transformations can we predict, if we apply quantum slip to this inertial frame of reference?

1. If Lorentz was correct in predicting that length would shrink, by beta, in the direction of motion, but not at right angles to the motion? In (PROBLEM TWO), I already discussed some of the conceptual problems with the Lorentz transformations. If the velocity and wave frequency, of the emitted photons, microwaves or particles, decrease by beta and the length of the mass is also dilated by beta, in the direction of motion, then an atomic clock, would only run slower than an atomic clock, which is relatively at rest, as long as the microwaves and emitted particles were at right angles to the direction of motion . If this was the case, then atomic clocks, would not be so accurate, over long periods of time, due to the fact that the orientation of the microwave and the emitted particles, would always be changing, relative to the inertial frame of reference, as the earth rotates on its axis and revolves about the sun.
Note: The physical models of electron orbitals, do tend to support the Lorentz transformations. The models indicate that most orbitals are aligned differently, relative to XYZ coordinates in space, but ---

2. I think it is more likely that quantum slip affects the velocity of electrons in all of the orbital shells. There might be a shrinkage of mass, in the direction of motion, but this would be offset by an elongation of mass in the opposite direction. In the case of a rocket traveling at half the speed of light, the nucleus, of each atom, is traveling at half the velocity of the electrons themselves. The electron orbitals may shift closer to the nucleus as it rotates around the nucleus, in the direction of motion, and farther from the nucleus, in the opposite direction of motion. The nuclear forces, within each atom, naturally adjust the angular momentum and velocity of orbiting electrons, to maintain stability. If this is correct, then the orientation of an atomic clock, relative to its motion, is irrelevant. The velocity and frequency of emitted photons, microwaves and particles would be slowed by beta, but the length of the mass would remain, relatively, the same. The frequency counter of the atomic clock, would record a slower time, than an atomic clock, which is relatively at rest.

PROBLEM ONE REVISITED:
Back in the previous post, my first logical problem, with special relativity, was that every observer, considers himself at rest, relative to the coordinate system, that they are observing. Each observer determined that the time in the other coordinate system, in motion, relative to themselves, was slower than their own time, due to relativistic effects of motion through space time. It is true, that it doesn't matter who is in motion, and who is at rest, when it comes to objects colliding with one another. If you throw a rubber ball 50 miles per hour, at a stopped car, it will bounce back x amount of feet. If you lob the ball, into the path of a car going 50 miles per hour, it too, will bounce x amount of feet. The object in motion, has kinetic energy, relative to the object at rest. If it is the kinetic energy of motion, that cause the quantum slip, then you can't apply relativistic math, to things which do not have real kinetic energy. The rocket that burned an enormous amount of fuel, to propel itself to .5C, has real kinetic energy. The observer at rest, relative to the rocket, did not change his velocity, and therefore his kinetic energy is the same. Relativity teaches that the observer on the rocket traveling at .5C, would consider himself at rest, and the earth, is receding from him at .5C and that Alpha Centauri C is approaching him at .5C. Neither the earth nor Alpha Centauri C, have the kinetic energy of a velocity of .5C. Therefore it is incorrect to apply relativistic math to these observed objects.

Shane



In the beginning. Man created God in his own image. Therefore we could say that God is the ultimate extension of the male penis. :eek:

[Tetlepanquetzatzin]

Originally posted by ShaneC
Now aychamo knows what I ment when I said that >
<<The how's and why's, of specail relativity are compex and subject to debate, but there is a great deal of physical evidence supporting the reality of time dilation.>>

Quote from Tetlepanquetzatzin
<<There is no explanation for time dilation. >>

Bob just gave one good explanation. Tetlepanquetzatzin,
Imagine that you live in 19:th century and had never heard of quantum mechanics? Special relativity was founded on pre -quantum physics. Knowledge of the atom, was still in its infancy.
Unfortunately, Jesse subsequently gave a good explanation of why BobK's explanation misses the mark.
In The Demon Haunted World by Carl Sagan, Sagan writes in chapter three, "Each field of science has its own complement of pseudoscience." --- "Physicists have perpetual motion machines, an army of amateur relativity disprovers, and perhaps cold fusion."
I don't think that every relativity disprovers, just doesn't understand relativity. Perhaps many of the relativity disprovers, like Bob and myself, feel strongly, that there is something wrong with the concepts of special relativity, have decided to analyze the theory to figure just what is wrong with it and to formulate a new model of special relativity.

To keep the post short, I will end for now, but will continue in another post latter.
The internal, logical consistency of the special theory of relativity is not open to question. It is futile to search for a Gedankenexperiment that will establish a kinematical inconsistency.

The solution to what you call PROBLEM ONE is to understand the mathematical structure of special relativity. All Lorentz transformations (or, more generally, all Poincaré transformations) together form a mathematical group (http://mathworld.wolfram.com/Group.html). This follows from the fact that the determinant of any matrix representing a Lorentz transformation is +1. The determinant of a product of Lorentz transformations is therefore also +1 (since 1 times 1 is 1) and any Lorentz transformation has an inverse, also with determinant +1. The group structure of the Lorentz transformations guarantees the internal consistency of SR. No matter how complicated Gedankenexperimente you invent all events will have unique space-time coordinates in a given coordinate system. The group structure ensures that if we take an event given in system 1, transform from system 1 to system 2, from 2 to 3, from 3 to 4, ..., from 16 to 17, and finally from 17 back to system 1 we get back the same coordinate point we started with. You can involve as many observers you like.

The solution to PROBLEM TWO is that time dilation is not associated with any spatial direction.

The solution to PROBLEM 3 is to simply do the calculation. When we do a Lorentz transformation between two systems, moving with velocity V relative to each other, velocities measured by first system will transform as

v' = (v - V) / (1 - vV/c^2)
u' = u sqrt(1 - V^2/c^2) / (1 - vV/c^2)

where v is the velocity component parallel to V (measured in the first system), u is the component perpendicular to V (measured in the first system), and primes denote the same quantities measured in the second system. Suppose that v = c and u = 0. What will v' and u' be then? Is the speed of light left unchanged by a Lorentz transformation?

[Jesse]

Bob K:
The real reason why clocks slow down, their rates of operation are less, and organisms appear to not age as much when accelerated as when not accelerated is the increase in inertial mass due to acceleration causes the internal stuffs of machines/organisms to move slower.

Think of swinging a ball around in a circle by a tether.

The faster you swing it/the more you accelerate it, the 'heavier' the ball seems, which is a subjective experience of the increase in the inertial mass of the accelerated ball; and the slower you swing it, the 'lighter' the ball seems, which is a subjective experience of the decrease in the inertial mass of the decelerated ball.

Jesse:
This phenomenon has nothing to do with the relativistic slowing of clocks; for example, if you attached a clock to the tether ball, you would not notice it ticking slower when you were swinging it more slowly (assuming that in both cases you're swinging it at a negligible fraction of light speed).

Bob K:
This phenomenon was mentioned by Albert E--he described it in reference to a rotating disc wherein a clock at the center would not slow down compared to a clock on the edge, which, when compared to the clock in the center, would slow down.

But I'm sure he was talking about a disc rotating at a sizeable fraction of the speed of light. In the case of swinging an ordinary tetherball around, the velocities are so small compared to light speed that relativistic effects are totally negligible. So, it is obviously nonsense to say that the increased feeling of heaviness when swinging a ball around at 5 miles per hour when compared with swinging it around at 10 miles per hour would have anything to do with relativity.

I am actually not quite sure about why the ball feels heavier in this case, though. I can set up some equations to show how the angle of the rope will get closer to horizontal the faster the ball is being swung around, and how the tension in the rope increases as the ball swings more quickly, but I'd have to think more about how muscles work and what makes things feel heavy to figure it out--do any other physics people here know the answer?

Bob K:
The rotating ball on a tether is similar to a rotating clock on a disc. Clearly, and obviously, to rotate a ball on a tether about your head you must accelerate the ball, thus you must increase its inertial mass, exactly as I have described.

Yes, but again, the increase in mass going from 5 mph to 10 mph (or whatever the typical speeds people swing balls around their head) is so tiny that it cannot possibly account for the different feeling of heaviness here. Are you seriously suggesting that it does? Would you like me to calculate the increase in mass in this case?

[aychamo]

Wow. This thread is off the hook. Lots of really interesting reading here.

Two more questions..

The first one is, you said its the person who is accelerated that will age slower. But if a spaceship is moving at a constant speed of .9c, is the spaceship technically accelerating? If he's moving at a constant speed, why is that different than if the spaceship is stationary and the mom on earth is moving away at .9c?

Let me clarify I'm not doubting SR, I am just trying to make sure I understand the basics.

Oh, and once my physics teacher said something muons or something, and that their half life makes them such that they should not make it onto planet earth, but for some reason they are accelerated to a high velocity and that makes them age slower so they are detectable on earth? Or something like that. Does anyone know where I can read more about that?

Thank you guys a lot
Aychamo

[Jesse]

Bob K:
Do we have means of determining if or not an air-borne or a space-borne clock is accelerated relative to a similar Earth-bound clock?

Yes, but the issue here is motion at constant relative velocities, not acceleration. When you have two clocks moving at constant velocities relative to one another, there is no way to determine which is "really" moving and which is "really" standing still. Likewise, if you have two objects that are known to have equal rest mass, and they are both moving at constant velocities relative to one another, then each will observe the other's mass to have increased, and there is no way to determine which one's mass has "really" increased.

Bob K:
I am preparing an exposition o