Effects of the multiverse theories on science

[Electric Plasma]

I found an interesting video which discusses the effects of the multiverse theory on the nature of science and certainty. This is one of the reasons that theists consider the multiverse to be unfalsifiable and unscientific.

Here is the link:

http://www.reasons.org/tnrtb/2008/05/28/multiverse-musings-does-the-multiverse-destroy-science/

[GenesisNemesis]

I don't know if the multiverse theory is accepted in the scientific community in general.

[Hedshaker]

This is one of the reasons that theists consider the multiverse to be unfalsifiable and unscientific.


Yet they find no problem with the notion of a talking snake and a dead guy coming back to life after being stone dead for three days, right? Double standards much....

[Electric Plasma]

I don't know if the multiverse theory is accepted in the scientific community in general.

That's true. There are many cosmologists and physicists who rightly reject the multiverse concept and it is not fully accepted by the scientific community. However, there are scientists such as Martin Rees who support this, as can be seen in his book Just Six Numbers. Also, the M-theory implies the existence of branes, which could possibly be other universes.

[elevator]

I found an interesting video which discusses the effects of the multiverse theory on the nature of science and certainty. This is one of the reasons that theists consider the multiverse to be unfalsifiable and unscientific.

Here is the link:

http://www.reasons.org/tnrtb/2008/05/28/multiverse-musings-does-the-multiverse-destroy-science/
Multiverse theory (I'll also mention higher dimensional universes and string theory) are all theories in their scientific infancy. They have not yet gone through the whole cycle of the scientific method; unlike Evolution, for example. From your post title it almost seems to me as though you are trying to present multiverse theory as a real scientific theory, then rip it apart (despite the fact that you probably know nothing of the underlying science of the theory - although correct me if I am wrong), and then conclude that because Multiverse theory is weak, other scientific theories must be weak too.

Your link seems to be doing exactly this - conclude that the weakness of a science in its infancy somehow destroys the credibility of well-established sciences. I fail to see how such a conclusion is possible.

[Civil1z@tion]

As of right now, string theory and the multiverse can basically be thought of as a mathematical thought experiment. Right now there is nothing beyond (mostly) internally consistent mathematics which proves they actually describe reality so there is still a lot of questions as to just how correct those theories are (at least that's my current understanding of string theory). This is of course, totally different from widely accepted scientific theories like relativity and evolution.

[thentian]

It sounded to me like they think the Many Worlds Interpretation (MWI) came in response to the Fine-tuning Argument, which it didn't; it emerged from observations made in Quantum Mechanics. It is also a proper scientific theory, because it explains some observations that are difficult to explain otherwise (e.g. in the experiment where they fire photons singly through a screen with two slits, where it looks like it is interacting with a non-existent photon. MWI explains that it is interacting with a real photon from a parallell world.), and there are ways to test the theory, so it should be possible to falsify it. Here (http://en.wikipedia.org/wiki/Elitzur-Vaidman_bomb-testing_problem) is one such experiment.

GenesisNemesis:
I don't know if the multiverse theory is accepted in the scientific community in general.

It doesn't seem to be accepted by a majority, no, but it is at least seen as a mainstream interpretation of QM. :)

I think David Deutsch argued strongly for it in an interview with Discover:

"Deutsch argues that physicists who use quantum mechanics in a utilitarian way— and that means most physicists working in the field today— suffer from a loss of nerve. They simply can't accept the strangeness of quantum reality. This is probably the first time in history, he says, that physicists have refused to believe what their reigning theory says about the world. For Deutsch, this is like Galileo refusing to believe that Earth orbits the sun and using the heliocentric model of the solar system only as a convenient way to predict the positions of stars and planets in the sky. Like modern physicists, who speak of photons as being both wave and particle, here and there at once, Galileo could have argued that Earth is both moving and stationary at the same time and ridiculed impertinent graduate students for questioning what that could possibly mean."

(Discover: 09.01.2001)

Cheers! :)

[mirage]

It sounded to me like they think the Many Worlds Interpretation (MWI) came in response to the Fine-tuning Argument, which it didn't; it emerged from observations made in Quantum Mechanics. It is also a proper scientific theory, because it explains some observations that are difficult to explain otherwise (e.g. in the experiment where they fire photons singly through a screen with two slits, where it looks like it is interacting with a non-existent photon. MWI explains that it is interacting with a real photon from a parallell world.), and there are ways to test the theory, so it should be possible to falsify it. Here (http://en.wikipedia.org/wiki/Elitzur-Vaidman_bomb-testing_problem) is one such experiment.
MWI isn't a proper theory, it is an interpretation of quantum mechanics.

An incoherent one at that.

For example it has the problem that if every possible outcome happens in some world, then how can we recover the probabilistic predictions of QM? What explains why we are more likely to be in world A rather than world B?

Apparently lots of physicists think MWI is non-bollocks, but I have yet to hear an explanation of this one, and I'm not above thinking some physicists can be quite thick. Penrose, that means you. (And Hawking, once, on the subject of temporal double standards).

I've read the Everett interpretation FAQ and it is a load of vague bollocks. As far as I can see they just rename the wave collapse into a world splitting event and then hand wave about why some things are more probable than others.

Re probability they have two options that I can see. They either have more worlds with more likely outcomes, which is just a clumsy way of having, er more likely outcomes in the first place, or they have weighted worlds which is...ditto.

If you have more world with the more likely outcome then that is an extra bit of theory. And what the fuck does more worlds mean when they are identical in every way and occupying the same space?

I think David Deutsch argued strongly for it in an interview with Discover:

"Deutsch argues that physicists who use quantum mechanics in a utilitarian way— and that means most physicists working in the field today— suffer from a loss of nerve. They simply can't accept the strangeness of quantum reality. This is probably the first time in history, he says, that physicists have refused to believe what their reigning theory says about the world. For Deutsch, this is like Galileo refusing to believe that Earth orbits the sun and using the heliocentric model of the solar system only as a convenient way to predict the positions of stars and planets in the sky. Like modern physicists, who speak of photons as being both wave and particle, here and there at once, Galileo could have argued that Earth is both moving and stationary at the same time and ridiculed impertinent graduate students for questioning what that could possibly mean."
He sounds like a moron. Ask him how he recovers any actual empirical predictions out of MWI.

[Gawen]

Moving this to S/S.

[thentian]

Well, I'm not counting myself as one who could explain it, but... have you seen this (http://jimschnabel.com/2007/09/27/existential-crisis-many-worlds-theory-confirmed/)?

EDIT: Oh, I just realized that what you're talking about is probably what Saunders is going on about in this (http://philsci-archive.pitt.edu/archive/00000465/00/Part3uj(S).pdf) paper. I have downloaded a bunch of such papers lately, but I must admit I'm having a hard time making sense of them. :blush:

[Abel]

It sounded to me like they think the Many Worlds Interpretation (MWI) came in response to the Fine-tuning Argument, which it didn't; it emerged from observations made in Quantum Mechanics. It is also a proper scientific theory, because it explains some observations that are difficult to explain otherwise (e.g. in the experiment where they fire photons singly through a screen with two slits, where it looks like it is interacting with a non-existent photon.

The better explanation of what's happening in this experiment is that the photon is interacting with itself; itself from a different time. It's difficult for me to wrap my mind around this concept, but it's far better, I think, than that of the MWI.

[thentian]

It sounded to me like they think the Many Worlds Interpretation (MWI) came in response to the Fine-tuning Argument, which it didn't; it emerged from observations made in Quantum Mechanics. It is also a proper scientific theory, because it explains some observations that are difficult to explain otherwise (e.g. in the experiment where they fire photons singly through a screen with two slits, where it looks like it is interacting with a non-existent photon.

The better explanation of what's happening in this experiment is that the photon is interacting with itself; itself from a different time. It's difficult for me to wrap my mind around this concept, but it's far better, I think, than that of the MWI.

Are we talking about Hawking's "Imaginary Time" here? The one that is at right angles to our time? And could you explain why you think it is far better? :)

[barbos]

I don't know if the multiverse theory is accepted in the scientific community in general.

Well, MWI (not exactly multiverse but still) interpretation of QM is quite popular and well accepted, I personally prefer it over copenhagen.

[GenesisNemesis]

Well, MWI (not exactly multiverse but still) interpretation of QM is quite popular and well accepted, I personally prefer it over copenhagen.

Aw, what's so bad about copenhagen? :D

[barbos]

Well, MWI (not exactly multiverse but still) interpretation of QM is quite popular and well accepted, I personally prefer it over copenhagen.

Aw, what's so bad about copenhagen? :D
For one, it is intrinsically probabilistic as opposed to MWI which is deterministic.

[uberhobo]

I'm partial to the "shut up and calculate" interpretation of QM, myself.

[thentian]

Well, MWI (not exactly multiverse but still) interpretation of QM is quite popular and well accepted, I personally prefer it over copenhagen.

Aw, what's so bad about copenhagen? :D

It gives you terrible headaches and makes you puke! :mad:

Oh... you meant the theory, not the city! Well, the city has far too cheap alcohol, don't know about the theory, though. For my part, I can't wrap my mind around little particles being unsure of what to do.

[barbos]

Well, the city has far too cheap alcohol.

It explains why this interpretation was born there :)

[ughaibu]

the city has far too cheap alcoholOnly a Norwegian (or a Swede) could think that!

[Smullyan-esque]

MWI isn't a proper theory, it is an interpretation of quantum mechanics.

An incoherent one at that.

For example it has the problem that if every possible outcome happens in some world, then how can we recover the probabilistic predictions of QM? What explains why we are more likely to be in world A rather than world B?

Apparently lots of physicists think MWI is non-bollocks, but I have yet to hear an explanation of this one,

Seems like you came up with a pretty good answer yourself later on:
Re probability they have two options that I can see. They either have more worlds with more likely outcomes, which is just a clumsy way of having, er more likely outcomes in the first place, or they have weighted worlds which is...ditto.

If you have more world with the more likely outcome then that is an extra bit of theory. And what the fuck does more worlds mean when they are identical in every way and occupying the same space?
It probably means something similar to what happens with photons in a lazer. Identical. All in the same space. Yet it is perfectly sensible to talk about have 'more' or 'less' photons.
and I'm not above thinking some physicists can be quite thick. Penrose, that means you!
I'm definitely with you on that. I've been profoundly underwhelmed by Penrose's reasoning in a lot of different areas.

[Yoo]

Aw, what's so bad about copenhagen? :D
Copenhagen requires wave function collapse. The problem is that what the collapse of a wave function is, how it occurs, and when it occurs is hand-waved as "when an observation occurs", with nothing approaching a rigorous definition. Considering that all known observers in the universe are also quantum mechanical systems, it's questionable to distinguish between quantum interactions and observations. (Some argue that at the macroscopic scale there will be something in the physical laws that corresponds to collapse, but there is as of yet no evidence for this.)

The many worlds interpretation simply says "there is no collapse", which is why I like it so much over the Copenhagen interpretation (and why I prefer it over other interpretations which seem more complicated). I actually prefer the original name of "relative-state formulation of quantum mechanics", since a lot of people think of multiple universes when hearing about the MWI. On the other hand, assuming the MWI is true, I have no idea whether it's the case that all possible macroscopic states exist or if it's the case that only one or a few macroscopic states exist indefinitely with the rest being cancelled out eventually.

I think the multiverse often mentioned in cosmology these days refers to something different, though. While in the MWI there is only one universe with one universal wave function which happens to have many macroscopic states that correspond to many "worlds", I have the impression that the multiple universes in multiverse theories indeed refer to multiple universes with separate physical constants and such. I'm rather skeptical of such multiverse theories.

[premjan]

I think the multiverse theory appears like overkill perhaps? Maybe there is some situation where the wave functions of observer and universe interact to become one wave function (i.e. merge). Maybe there is some other process that causes them to split. That seems more parsimonious, but I don't know the math.

[Abel]

The better explanation of what's happening in this experiment is that the photon is interacting with itself; itself from a different time. It's difficult for me to wrap my mind around this concept, but it's far better, I think, than that of the MWI.

Are we talking about Hawking's "Imaginary Time" here? The one that is at right angles to our time? And could you explain why you think it is far better? :)

Let's just say that it's more soothing for me to think that what happens in this universe stays in this universe. I do like Hawking's imaginary time and I'm glad you mentioned it. I need to re-read A Brief History of Time.

In the experiment a single photon is observed to pass through both slits. How can this be possible? Are we seeing another exotic effect of the speed of light? Is the trough of the photon's wave in a different time than the crest? Am I understanding the results of the experiment correctly? Am I going mad? I dunno. Could be.:)

[thentian]

Let's just say that it's more soothing for me to think that what happens in this universe stays in this universe. I do like Hawking's imaginary time and I'm glad you mentioned it. I need to re-read A Brief History of Time.

In the experiment a single photon is observed to pass through both slits. How can this be possible? Are we seeing another exotic effect of the speed of light? Is the trough of the photon's wave in a different time than the crest? Am I understanding the results of the experiment correctly? Am I going mad? I dunno. Could be.:)

I think it is a little misleading to talk of "many worlds", because they all originated from the same Big Bang singularity, so it can be thought of as one universe, IMO. Except that maybe a better name than "universe" ought to be found?

The thing that used to bug me about the split screen experiment was the only explanation given in the first book on QM that I read: "The photon is both a particle and a wave." I just can't wrap my mind around that idea! I'm much more happy with our photon interacting with a photon from "the next world over." :)

[Simen]

The thing that used to bug me about the split screen experiment was the only explanation given in the first book on QM that I read: "The photon is both a particle and a wave." I just can't wrap my mind around that idea! I'm much more happy with our photon interacting with a photon from "the next world over." :)

That doesn't sound like MWI at all. Neither does the denial of wave-particle duality.

[Abel]

The thing that used to bug me about the split screen experiment was the only explanation given in the first book on QM that I read: "The photon is both a particle and a wave."

Would you mind sharing the title of the book? I'd like to know if I've read it and, if not, add it to my to-do list.

I just can't wrap my mind around that idea! I'm much more happy with our photon interacting with a photon from "the next world over." :)

I'm from the opposite camp. I can't accept the philosophy-sounding MWI theory. I'm much happier with the very young M-theory,which, I think jives better with Hawking's theories on time. While it does include the possibility of multiple universes, their interactions seem more intuitively logical. But that's just me.

I wish I could take a tour of Hawking's mind.

[mirage]

Well, I'm not counting myself as one who could explain it, but... have you seen this (http://jimschnabel.com/2007/09/27/existential-crisis-many-worlds-theory-confirmed/)?

EDIT: Oh, I just realized that what you're talking about is probably what Saunders is going on about in this (http://philsci-archive.pitt.edu/archive/00000465/00/Part3uj(S).pdf) paper. I have downloaded a bunch of such papers lately, but I must admit I'm having a hard time making sense of them. :blush:

Oh gawd! That Saunders link is a good example of the very worst kind of philosophical drivel. (NB I like philosophy - good philosophy). You just get the idea that he doesn't really have a clue what the central problems are and can't talk clearly about them. It's impossible to read but I just couldn't find anything there that suggested he even understood the probability problem, let alone had found a solution.

The problem is that the very thing that people object to in Copenhagen is just reproduced unacknowledged in Everett interpretation.

We observe probability frequencies in discrete macroscopic outcomes. Copenhagen invents the wave collapse to cover this.

Everett either ignores it or handwaves something about the "thickness" or number of worlds of the more likely outcome.

What is so preferable about some handwaving crap like that compared to wave collapse? Especially if you have had to invoke an infinite number of parallel universes for it?

[mirage]

[QUOTE=Abel;5367771]
I think it is a little misleading to talk of "many worlds", because they all originated from the same Big Bang singularity, so it can be thought of as one universe, IMO. Except that maybe a better name than "universe" ought to be found?


Indeed. One world with many simultaneous outcomes. And notice how when we observe the outcome of an experiment we just seem to "collapse" into one version of the outcome and the others become invisible to us?

Thank God we got rid of that God-awful Copenhagen interpretation with its stupid wave collapse though!

[mirage]

MWI isn't a proper theory, it is an interpretation of quantum mechanics.

An incoherent one at that.

For example it has the problem that if every possible outcome happens in some world, then how can we recover the probabilistic predictions of QM? What explains why we are more likely to be in world A rather than world B?

Apparently lots of physicists think MWI is non-bollocks, but I have yet to hear an explanation of this one,

Seems like you came up with a pretty good answer yourself later on:

It probably means something similar to what happens with photons in a lazer. Identical. All in the same space. Yet it is perfectly sensible to talk about have 'more' or 'less' photons.

More photons has more intensity and energy density.

More worlds has what? Probability is what. You can invent other names for this variable, but I'll still know what you're talking about you equivocating MWI enthusiasts! I am not fooled by you substituting the phrase "more worlds" for "more probable". This name change does not change the structure of the theory.

[javarush]

As of right now, string theory and the multiverse can basically be thought of as a mathematical thought experiment. Right now there is nothing beyond (mostly) internally consistent mathematics which proves they actually describe reality so there is still a lot of questions as to just how correct those theories are (at least that's my current understanding of string theory). This is of course, totally different from widely accepted scientific theories like relativity and evolution.


That's right. Until the formalism produces a quantifiable prediction which is subsequently verified, it's just beautiful ideas and mathematics. The prediction(s) must be the result of calculation, not from an arm-flapping argument based on interpretations of the formalism.

[Smullyan-esque]

Seems like you came up with a pretty good answer yourself later on:

It probably means something similar to what happens with photons in a lazer. Identical. All in the same space. Yet it is perfectly sensible to talk about have 'more' or 'less' photons.

More photons has more intensity and energy density.

More worlds has what? Probability is what. You can invent other names for this variable, but I'll still know what you're talking about you equivocating MWI enthusiasts! I am not fooled by you substituting the phrase "more worlds" for "more probable". This name change does not change the structure of the theory.I'm not sure I understand your objection.

If you take a checkerboard, and color 60 of the squares blue, and 4 green, and you throw a dart at the checkerboard, what color is it more likely to hit?

If you have more identical possibilities, they are more likely to occur.

Why is this a controversial idea?

I'm not particularly fond of the Many Worlds Interpretation. I'm actually more of a "do the stupid math, and ignore the philosophy" type. My own objection is that MWI seems unparsimonious to me. But, really, that's just a gut-level objection, and I can't really seem to form a scientific objection.

[J842P]

I don't know if the multiverse theory is accepted in the scientific community in general.

That's true. There are many cosmologists and physicists who rightly reject the multiverse concept and it is not fully accepted by the scientific community. However, there are scientists such as Martin Rees who support this, as can be seen in his book Just Six Numbers. Also, the M-theory implies the existence of branes, which could possibly be other universes.

M-Theory is also no where near accepted.

[Species8472]

As of right now, string theory and the multiverse can basically be thought of as a mathematical thought experiment. Right now there is nothing beyond (mostly) internally consistent mathematics which proves they actually describe reality so there is still a lot of questions as to just how correct those theories are (at least that's my current understanding of string theory). This is of course, totally different from widely accepted scientific theories like relativity and evolution.

I attended a guest lecture last year about a certain aspect of string theory/multiverse theory where the number of families in the standard model varies and produce different realities. It was all very confuzzeling, and to me as a physicists based on too much math and too little evidence.

Around here string theory is described as mathematicians (who incidentally has a different approach to fact than scientists) going bananas on QM.

My point is that multiverse theory and string theory is, as Civil1z@tion points out, that these theories are based on math, not evidence, and thus not science in the sense of the word that the OP seems to assume.

I personally am very skeptical towards multiverse theory, and I don't like string theory much either.

[Abel]

I'm not particularly fond of the Many Worlds Interpretation. I'm actually more of a "do the stupid math, and ignore the philosophy" type. My own objection is that MWI seems unparsimonious to me. But, really, that's just a gut-level objection, and I can't really seem to form a scientific objection.

What can be more parsimonious than math? Alone it stands as a sufficient scientific confirmation of the validity of the M-theory for me. As we humans explore "where no one has gone before" and aren't likely ever to go, we will become ever more dependent on the theoretical, and not the practical, in comprehending the unknown. Math is the language of the theoretical and keeps us rigidly focused on the path to knowledge. It certainly excludes the human tendency to succumb to the romance of imagination.

[Abel]

I personally am very skeptical towards multiverse theory, and I don't like string theory much either.

Skepticism is certainly appropriate at this stage of M-theory development. Regarding string theory, I like the thought that at the basis of everything it's interacting energy bands that ultimately compose me, you and everything else. We would, of course, have to redefine energy as we know it.

[mirage]

More photons has more intensity and energy density.

More worlds has what? Probability is what. You can invent other names for this variable, but I'll still know what you're talking about you equivocating MWI enthusiasts! I am not fooled by you substituting the phrase "more worlds" for "more probable". This name change does not change the structure of the theory.I'm not sure I understand your objection.

If you take a checkerboard, and color 60 of the squares blue, and 4 green, and you throw a dart at the checkerboard, what color is it more likely to hit?

If you have more identical possibilities, they are more likely to occur.

Why is this a controversial idea?

I'm not particularly fond of the Many Worlds Interpretation. I'm actually more of a "do the stupid math, and ignore the philosophy" type. My own objection is that MWI seems unparsimonious to me. But, really, that's just a gut-level objection, and I can't really seem to form a scientific objection.

The problem is the inconsistency. MWI enthusiasts think they have got rid of wave collapse type probabilistic trial outcome events.

Yet they need to recreate their very own probabilistic trial outcome events in the form of a dice roll between which particular world we will end up in.

You might say that there are just more worlds with the "likelier" outcome and all of them exist. You might say that there are simply more instances of each of us in the "likely" worlds and that it is therefore more likely that any one of us are in such a world.

But what the hell does an assertion of "more" worlds mean when each "instance" of these things is identical in every respect, including temporal and spatial? My understanding of the identity relation suggests that if two things are identical they are actually just one thing.

How is it in fact any different to simply saying that it is just more likely that we find ourselves in world A?

And if us finding ourselves in world A is just more likely, then how is this trial/outcome any different in structure to the wave collapse way of saying the same thing?

MWI as it stands is just a bunch of unnecessary ontological assertions. Oh the other worlds "really exist", do they? What are the consequences? Just the same as the Copenhagen. Right.

Except that we need a new term, perhaps "really really exist" to differentiate the outcomes we observe from the "really" existing ones that we don't and can't.

Everett interpreters are confused about what exists means. It means has potential or actual observational consequence.

Scientific theories are grounded in and understood in terms of their observational consequences.

MWI has forgotten that and thought it could get away with not actually describing what we experience. Unfortunately this has the consequence of rendering its ontological assertions meaningless.

[Smullyan-esque]

But what the hell does an assertion of "more" worlds mean when each "instance" of these things is identical in every respect, including temporal and spatial? My understanding of the identity relation suggests that if two things are identical they are actually just one thing.This is what originally got me to jump in with my example of photons in a lazer.

Things that are identical in all respects are not necessary just one thing. Two photons can both be totally identical, down to their quantumn numbers and everything, in the same location, at the same time, yet still be TWO photons.

Go ahead and dislike the MWI. But please don't object this way. It is an objection that goes counter to actual physics.

[Yoo]

The problem is the inconsistency. MWI enthusiasts think they have got rid of wave collapse type probabilistic trial outcome events.

Yet they need to recreate their very own probabilistic trial outcome events in the form of a dice roll between which particular world we will end up in.

One thing that makes me prefer many worlds over Copenhagen is that it requires one less ill-defined element, the wave function collapse. But this is just a personal aesthetic preference, since currently there is no difference in the predictions between the interpretations. So I have absolutely no vehement reaction to different interpretations, although admittedly I do have some reaction to vehement statements about the many worlds interpretation. :)

However, one thing in favor of the many worlds interpretation is that there is actual progress in the explanation of the appearance of our probabilistic reality in the form of decoherence (http://en.wikipedia.org/wiki/Quantum_decoherence). This is the evolution of a wave function into the superposition of two or more macroscopic states, but due to the linear nature of quantum mechanics, these macroscopic states evolve independently of each other. In other words, they behave like many worlds. Mind you, this is what the current mathematics of quantum mechanics predicts and is not some hand waving done to support MWI.

While I don't think current knowledge of quantum decoherence is enough to completely or even just largely justify the many worlds interpretation yet, there are experimental results that have actually observed decoherence in progress at least on the small scale. Which is another plus for many worlds over Copenhagen, since there is absolutely no experimental evidence for an actual mechanism of collapse as of yet. (This is not to say that there is no evidence at all, since we actually do observe at least apparent collapse, of course, but what I mean is that we don't have anything on the actual mechanics of collapse.)

[SteveP]

I'm not particularly fond of the Many Worlds Interpretation. I'm actually more of a "do the stupid math, and ignore the philosophy" type. My own objection is that MWI seems unparsimonious to me. But, really, that's just a gut-level objection, and I can't really seem to form a scientific objection.

What can be more parsimonious than math? Alone it stands as a sufficient scientific confirmation of the validity of the M-theory for me. As we humans explore "where no one has gone before" and aren't likely ever to go, we will become ever more dependent on the theoretical, and not the practical, in comprehending the unknown. Math is the language of the theoretical and keeps us rigidly focused on the path to knowledge. It certainly excludes the human tendency to succumb to the romance of imagination.

I disagree that maths can provide scientific confirmation of theory. To me that smacks of the ancient greek philosophy that pure thought should not be sullied by crass real world considerations.

Maths is undoubtedly a vital tool, but I think it only gives possibilities of what might be, but what actually is of those possibilities can only be determined empirically (ie "scientifically").

As I understand it, String Theory should be more accurately called a group of of theories (10^500 theories is one figure I've read), with no way of determining emprically which of those is "correct", ie which corresponds to the actual universe we find ourselves in.

A crude analogy: Maxwell mathematically derived the speed of light from the permeability and permissivity of free space. However you still can't determine the actual value of c from that derivation without knowing the values of those constants, which must be determined by empirical measurement (Now that's not to say that at some time in the future those constants won't fall out of some yet to be constructed TOE; after all one of the aims of physics is to reduce the number of seemingly arbitrary constants that have to be plugged into a theory to make it work. We're still a long way off that though).

Of course Maxwell's equation ties together nicely with the speed of light as determined by other experiments, but again we still actually have to measure c before we know the equation is correct (I suppose you could just say I'm not a Platonist).

I think that weird counter-intuitive quantum phenomena such as the dual slit experiment, rotation of 1/2 spin particles (fermions) and quantum entanglement are most likely to be explained as extra-dimensional properties of sub-atomic "particles" - anyone who has read the Flatland stories knows how extra dimensions can lead to baffling properties, and quantum phenomena seem to me to be exactly the kinds of things you'd see.

I don't know enough about current theory though to say if compactified dimensions explain quantum phenomena; brane theory seems more applicable... I await being torn to shreds by those more knowledgeable! :D

[Abel]

I disagree that maths can provide scientific confirmation of theory.

Well, this statement might bring rain from the purists on the board.:eek:


Maths is undoubtedly a vital tool, but I think it only gives possibilities of what might be, but what actually is of those possibilities can only be determined empirically (ie "scientifically").

I agree that it's the best tool we have to focus in on possibilities. I just feel that we must use math to explore those areas of science for which we cannot yet gain empirical information.

As I understand it, String Theory should be more accurately called a group of of theories (10^500 theories is one figure I've read), with no way of determining emprically which of those is "correct", ie which corresponds to the actual universe we find ourselves in. When a theory is as young as is string theory, there will, of course, be competing sub-theories. That's logical and healthy in my opinion. That's what I love about science. Almost no idea progresses without the most strenuous scrutiny possible prior to its acceptance; and even that acceptance seems permanently conditional.

I think that weird counter-intuitive quantum phenomena such as the dual slit experiment, rotation of 1/2 spin particles (fermions) and quantum entanglement are most likely to be explained as extra-dimensional properties of sub-atomic "particles" - anyone who has read the Flatland stories knows how extra dimensions can lead to baffling properties, and quantum phenomena seem to me to be exactly the kinds of things you'd see.

I concur. I think it's important to minimize the importance of the "human experience" in order to understand quantum mechanics and the "newness" of information that flows out of experiments involving particles and energy at this level. We should all be like Zack on the television show "Bones." Zack is ruled by logic alone and suppresses his emotions and other human "illogic" when he observes the world.

I don't know enough about current theory though to say if compactified dimensions explain quantum phenomena; brane theory seems more applicable... I await being torn to shreds by those more knowledgeable! :D
I find no problem, personally, with "being torn to shreds" if I learn something as an outcome of the experience. :)

[LeoM]

The problem is the inconsistency. MWI enthusiasts think they have got rid of wave collapse type probabilistic trial outcome events.

Yet they need to recreate their very own probabilistic trial outcome events in the form of a dice roll between which particular world we will end up in.

One thing that makes me prefer many worlds over Copenhagen is that it requires one less ill-defined element, the wave function collapse. But this is just a personal aesthetic preference, since currently there is no difference in the predictions between the interpretations. So I have absolutely no vehement reaction to different interpretations, although admittedly I do have some reaction to vehement statements about the many worlds interpretation. :)

However, one thing in favor of the many worlds interpretation is that there is actual progress in the explanation of the appearance of our probabilistic reality in the form of decoherence (http://en.wikipedia.org/wiki/Quantum_decoherence). This is the evolution of a wave function into the superposition of two or more macroscopic states, but due to the linear nature of quantum mechanics, these macroscopic states evolve independently of each other. In other words, they behave like many worlds. Mind you, this is what the current mathematics of quantum mechanics predicts and is not some hand waving done to support MWI.

While I don't think current knowledge of quantum decoherence is enough to completely or even just largely justify the many worlds interpretation yet, there are experimental results that have actually observed decoherence in progress at least on the small scale. Which is another plus for many worlds over Copenhagen, since there is absolutely no experimental evidence for an actual mechanism of collapse as of yet. (This is not to say that there is no evidence at all, since we actually do observe at least apparent collapse, of course, but what I mean is that we don't have anything on the actual mechanics of collapse.)

Unless consciousness causes the collapse of the wave function.

[Yoo]

Unless consciousness causes the collapse of the wave function.
Like I said, there's no direct experimental observation of the actual mechanics of wave function collapse.

[Yoo]

I agree that it's the best tool we have to focus in on possibilities. I just feel that we must use math to explore those areas of science for which we cannot yet gain empirical information.
While I feel the same, I have negative feelings for string theory. This is not because I believe that it must be wrong, but because it has mostly crowded out alternative approaches despite there not being a shred of experimental evidence for the theory. Not that research into alternative approaches has been extinguished, but I would like to see a more balanced allocation of resources.

And this is off topic, but has string theory actually managed to reduce to general relativity and the standard model in their respective domains? The last I've heard, which was quite a while ago, was that string theory predicted a spin-two massless particle, so the fact that it was a quantum theory that seemed to predict the graviton was the biggest factor in its favor.

[SteveP]

I disagree that maths can provide scientific confirmation of theory.

Well, this statement might bring rain from the purists on the board.:eek:




I agree that it's the best tool we have to focus in on possibilities. I just feel that we must use math to explore those areas of science for which we cannot yet gain empirical information.

Well if it's between maths and say, reading chicken entrails I know what my money's on (no, not the chicken guts).

When a theory is as young as is string theory, there will, of course, be competing sub-theories. That's logical and healthy in my opinion. That's what I love about science. Almost no idea progresses without the most strenuous scrutiny possible prior to its acceptance; and even that acceptance seems permanently conditional.

Absolutely. How boring would it be if you could just look up all the answers in some big old book?

I don't know enough about current theory though to say if compactified dimensions explain quantum phenomena; brane theory seems more applicable... I await being torn to shreds by those more knowledgeable! :D
I find no problem, personally, with "being torn to shreds" if I learn something as an outcome of the experience. :)

For sure, after all this is a discussion board: you put your opinions out there to be critiqued by others, though some people seem to have forgotten the bit about "learning"... (not directed at you Abel)

[Tim Thompson]

I disagree that maths can provide scientific confirmation of theory. ... Maths is undoubtedly a vital tool, but I think it only gives possibilities of what might be, but what actually is of those possibilities can only be determined empirically (ie "scientifically").
I agree with SteveP, mathematics cannot confirm. But I also point out that mathematics is surprisingly revealing of nature. Even something as counterintuitive as Heisenberg's uncertainty principle can be derived from the mathematics of Fourier transforms, without appeal to "physics". Chaos Theory (which is not chaotic despite the name) was discovered through mathematics by Poincare, long before anyone thought of it as a physical reality.

Of course, not all surprising mathematics turns out to be physically significant. Nevertheless, the surprising success of mathematics makes it a valid field of scientific investigation. I think that mathematics can be just as revealing as any physical experiment, as to the nature of physical reality. But only observation in physical experiment can confirm the physical interpretation of any mathematical investigation.

And this is off topic, but has string theory actually managed to reduce to general relativity and the standard model in their respective domains?
General relativity, yes. String theory completely contains general relativity. That's the main reason why it is theoretically popular; not only is it known to reduce to general relativity in the classical limit, but it also includes gravitons in its particle inventory. That makes string theory, at least in principle, a genuine quantum theory of gravity. Whether or not it is the quantum theory of gravity remains to be seen.

String theory can generate a Minimal Supersymmetric Standard Model (MSSM), which is encouraging I suppose, but the standard model itself has not been reproduced from string theory that I know of.

[LeoM]

What about quantum immortality that conscious beings are immortal?

http://en.wikipedia.org/wiki/Quantum_suicide

[SteveP]

I disagree that maths can provide scientific confirmation of theory. ... Maths is undoubtedly a vital tool, but I think it only gives possibilities of what might be, but what actually is of those possibilities can only be determined empirically (ie "scientifically").
I agree with SteveP, mathematics cannot confirm. But I also point out that mathematics is surprisingly revealing of nature. Even something as counterintuitive as Heisenberg's uncertainty principle can be derived from the mathematics of Fourier transforms, without appeal to "physics".

Correct me if I'm wrong, but isn't it the case that a mathematical derivation of HUP from Fourier wouldn't give you a non-zero value for the Planck constant?

That may sound like nit-pickery, after all it's just a constant in a very important equation, but isn't the whole point of the HUP the fact that the Planck constant, while small, isn't zero?

Chaos Theory (which is not chaotic despite the name) was discovered through mathematics by Poincare, long before anyone thought of it as a physical reality.

That is a very good illustration of the power of mathematics. I've read that years before Watson and Crick, a mathematician predicted that the double-helix would be a likely biological structure, based on the chemical building blocks on which biology is based (dang I can't find the name of that mathematician).

Of course, not all surprising mathematics turns out to be physically significant. Nevertheless, the surprising success of mathematics makes it a valid field of scientific investigation. I think that mathematics can be just as revealing as any physical experiment, as to the nature of physical reality. But only observation in physical experiment can confirm the physical interpretation of any mathematical investigation.

It's certainly an astonishing achievement that Einstein simply by making chalk marks on a blackboard was able to show that the Universe had to be either expanding or contracting (so amazing that even Einstein himself couldn't believe it at first... that in itself is an interesting point. It seems contemporary thinking in Astronomy prejudiced Einstein against his own discovery).

That was a major discovery about the fundamental nature of the Universe, however implicit in Einstein's calculations was experimental evidence gained previously (Michelson-Morley etc).

I'm still skeptical that mathematics can tell you something about the world that you don't, in some way, already know.

[Tim Thompson]

Correct me if I'm wrong, but isn't it the case that a mathematical derivation of HUP from Fourier wouldn't give you a non-zero value for the Planck constant?
The mathematical derivation only shows that there is a natural uncertainty between Fourier transform pairs, it actually says nothing at all about the value of Planck's constant. The point for me is that the derivation of the uncertainty relationship is entirely mathematical, and there is no reason to believe a priori that it has anything at all to do with physics. But if you have a mathematical description of a physical system, and it shows physical quantities to be Fourier transform pairs, then the physical world is found to indeed obey the strictly mathematical requirement between such pairs. I see that as evidence of a deeper relationship between mathematics & physics. See Fourier Transforms and Uncertainty Relations (http://www.mathpages.com/home/kmath488/kmath488.htm) from the Mathpages website (http://www.mathpages.com/).

[SteveP]

LOL yes I found that page when I was writing my post... it's certainly the case that the same maths can spookily work for apparently completely disparate phenomena!

[LeoM]

I guess I won't get any response about quantum immortality no surprise there though:)

[thentian]

That doesn't sound like MWI at all. Neither does the denial of wave-particle duality.

I guess I'm talking very loosely, which is because my understanding of the subject is still very loose! :blush:

The thing that used to bug me about the split screen experiment was the only explanation given in the first book on QM that I read: "The photon is both a particle and a wave."

Would you mind sharing the title of the book? I'd like to know if I've read it and, if not, add it to my to-do list.


I don't have that book anymore, but I remember it was written in Norwegian (possibly translated from english) and was a sort of "popular science" book for the general public. I'm afraid I don't remember the title or who wrote it, but I doubt a such a book from around 1980 would tell you anything you don't know already! :)

It didn't say exactly what I wrote above, I think, but that is how I interpreted it. Basically, it gave the copenhagen interpretation and no other explanation. The book also had something about Schrödinger's cat, which I also couldn't wrap my mind around. I felt sure that the cat would have to be either dead or alive, and not something "in between". For these reasons I always distrusted QM, notwithstanding that it made accurate predictions, because I felt there had to be some better explanation.


I'm from the opposite camp. I can't accept the philosophy-sounding MWI theory. I'm much happier with the very young M-theory,which, I think jives better with Hawking's theories on time. While it does include the possibility of multiple universes, their interactions seem more intuitively logical. But that's just me.


I just googled M-theory, so now I have much more reading material. Thanks! :)

Well, I'm not counting myself as one who could explain it, but... have you seen this (http://jimschnabel.com/2007/09/27/existential-crisis-many-worlds-theory-confirmed/)?

EDIT: Oh, I just realized that what you're talking about is probably what Saunders is going on about in this (http://philsci-archive.pitt.edu/archive/00000465/00/Part3uj(S).pdf) paper. I have downloaded a bunch of such papers lately, but I must admit I'm having a hard time making sense of them. :blush:

Oh gawd! That Saunders link is a good example of the very worst kind of philosophical drivel. (NB I like philosophy - good philosophy). You just get the idea that he doesn't really have a clue what the central problems are and can't talk clearly about them. It's impossible to read but I just couldn't find anything there that suggested he even understood the probability problem, let alone had found a solution.


I've only read the paper once so far (usually have to read such things at least three times), but I agree he does ramble on a lot without getting to the point! Still, his papers are much easier for me to read than those I've found by Deutsch. (Too much maths and symbols)

There was a conference at the Perimeter Institute in Canada that I'd like to know more about. I found some abstracts (http://www.perimeterinstitute.ca/Events/Many_Worlds_at_50/Abstracts/), but I wonder if there is some more detailed information to be found somewhere? It looks like it's the philosophers against the mathematicians on this subject?

Cheers! :)

[dlawbailey]

The multiverse is an answer to some of the problems that come - in my view - from single-cause determinism or the idea that all causality flows probabilistically from one original moment in time.

If looked at closely, this does tend to start making the probabilities pretty small for all sorts of things.

But I think the multiverse is just a "working title", if you will for efforts to develop a cosmological equivalent to Punctuated Equillibrium.

In my humble view, the answer is sort of simple, but slightly confusing.

That is, I think there is multiple-cause determinism. That is, that the Universe works deterministically but there is more than one chain of causality and these chains interact. And this is not really all that hard to imagine. No matter when you want to start causality, just start it with more than one beginning point - like multiple cars on a racetrack that go forever, but influence each other. You can have new causal chains enter the "race" - like new cars. Or you can have them starting and ending - like runners in a relay.

Personally, I think causalities start and end, but any way you want to look at it, the Universe is a lot freer place with multiple causalities.