Why is quantum so fundamental?

[Kherubin]

I have recently been reading some of the slew of additions to the genre of layman's cosmology detailing the possibility of one (if not many!) multiverse theories. The books that I have read (including Greene's and Barrowman's) have been truly informative and I highly recommend them.

I am, however, left with one question.

Every time the authors deal with processes seemingly 'fundamental' to the evolution of their multiverse, be that inflating bubbles adopting particular vacuum energies according to quantum principles, or the quantum tunneling of universes between distinct valleys in the string landscape, they appear, still, to operate on the basis of quantum rules.

My questions is, why does the quantum, to coin a term, 'subsede' all these other theories?

That is to say, why (and how) is it written into the cosmic underpinnings that even theories as 'fundamental' as string theory have to adopt a quantum nature?

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

 

[DaveC426913]

Because that's what our observations are telling us.

Quantum mechanics is spectacularly good at making predictions of what we observe.

As David Mermin meant when he quipped "Just shut up and calculate", we're not clear why QM works, but we're very clear that it does so very well.

 

[Demystifier]

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

"Quantum" physics us actually a misnomer. Quantization does not necessarily imply that nature is not continuous.

 

[Kherubin]

As David Mermin meant when he quipped "Just shut up and calculate", we're not clear why QM works, but we're very clear that it does so very well.

So, we don't know why it is more 'fundamental' than even these theories, it's just clear that it is?

"Quantum" physics us actually a misnomer. Quantization does not necessarily imply that nature is not continuous.

Could you please clarify? Our universe may be continuous, but simply quantizable?

 

[Demystifier]

Could you please clarify? Our universe may be continuous, but simply quantizable?

Yes. The key property of "quantization" is not that physical values appear in "quanta" (sometimes they don't). The key property is the uncertainty principle, which says that certain pairs of quantities (e.g. position AND momentum) cannot be simultaneously measured.

Instead of calling it "quantum physics" perhaps we should call it "uncertain physics". But the name is stuck, so ...

 

[Kherubin]

Yes. The key property of "quantization" is not that physical values appear in "quanta" (sometimes they don't). The key property is the uncertainty principle, which says that certain pairs of quantities (e.g. position AND momentum) cannot be simultaneously measured.

Ah, thank you. Very well then, perhaps I should rephrase my question. Is it possible to conceive of universes in which this "uncertain physics" does not operate?

If so, how would they look and, perhaps more importantly, how would they differ from ours?

 

[DaveC426913]

Ah, thank you. Very well then, perhaps I should rephrase my question. Is it possible to conceive of universes in which this "uncertain physics" does not operate?

Certainly. A Newtonian deterministic universe. The way we thought it was until QM came along.

If so, how would they look and, perhaps more importantly, how would they differ from ours?

Of course we have no idea.

 

[Varon]

I have recently been reading some of the slew of additions to the genre of layman's cosmology detailing the possibility of one (if not many!) multiverse theories. The books that I have read (including Greene's and Barrowman's) have been truly informative and I highly recommend them.

I am, however, left with one question.

Every time the authors deal with processes seemingly 'fundamental' to the evolution of their multiverse, be that inflating bubbles adopting particular vacuum energies according to quantum principles, or the quantum tunneling of universes between distinct valleys in the string landscape, they appear, still, to operate on the basis of quantum rules.

My questions is, why does the quantum, to coin a term, 'subsede' all these other theories?

That is to say, why (and how) is it written into the cosmic underpinnings that even theories as 'fundamental' as string theory have to adopt a quantum nature?

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

It's possible the quantum nature may be so in order that information are discrete (and not continuous) so it can be modeled by 0 and 1 and pixelized and processed.

 

[computerphys]

Is it possible to conceive of universes in which this "uncertain physics" does not operate?

This question is out of science, but nevertheless it is a very interesting question. Science cannot tell a thing about something we cannot measure. Philosophy instead could shed some light here.

Depending on the metaphysics applied conclusions are very different. In a metaphysics where consciousness requires uncertainty, that universe would lack of observers. In that case probably there is no difference saying it could exist or it don't exist, or it doesn't worth exist.

Other people may conclude other things using other metaphysics.

 

[maverick_starstrider]

This question is out of science, but nevertheless it is a very interesting question. Science cannot tell a thing about something we cannot measure. Philosophy instead could shed some light here.

Depending on the metaphysics applied conclusions are very different. In a metaphysics where consciousness requires uncertainty, that universe would lack of observers. In that case probably there is no difference saying it could exist or it don't exist, or it doesn't worth exist.

Other people may conclude other things using other metaphysics.

That's really just a fancy way of telling us that "philosophy" can't tell us a stinking thing, and is a colossal waste of time.

 

[maverick_starstrider]

I have recently been reading some of the slew of additions to the genre of layman's cosmology detailing the possibility of one (if not many!) multiverse theories. The books that I have read (including Greene's and Barrowman's) have been truly informative and I highly recommend them.

I am, however, left with one question.

Every time the authors deal with processes seemingly 'fundamental' to the evolution of their multiverse, be that inflating bubbles adopting particular vacuum energies according to quantum principles, or the quantum tunneling of universes between distinct valleys in the string landscape, they appear, still, to operate on the basis of quantum rules.

My questions is, why does the quantum, to coin a term, 'subsede' all these other theories?

That is to say, why (and how) is it written into the cosmic underpinnings that even theories as 'fundamental' as string theory have to adopt a quantum nature?

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

People have more or less skated around the issue but I don't think anyone's really hit it on the head. It's not that quantum is "more fundamental" but rather that it is the most experimentally accurate theory ever devised. Thus, whatever the equations and underscoring metaphysics of some new fangled theory of everything, in some limit (typically at low enough energies and at atomic distances) they must reduce to the equations of quantum mechanics. Why? Because we know quantum mechanics gives the right answer in these cases.

A very similar thing occurred when quantum mechanics itself was first developed. People knew that classical physics (i.e. Newton's Laws, etc.) was quite accurate for most cases. Thus they devised something called the "correspondence principle" which simply says that any deeper theory (what we now call quantum theory) would have to reduce to the same equations as Newton's Laws when systems sizes were sufficiently large (and they do).

In a nutshell, though new theories may illuminate deeper underpinnings to the theories we already have, the ones we have now are extremely accurate at predicting the results of pretty much ever experiment under the sun (not entirely true but you get the point). Thus, the baby, so to speak, can't go out with the bathwater. New theories have to behave like the old theories in the situations where the old theories gave the right answer.

 

[The_Duck]

Ah, thank you. Very well then, perhaps I should rephrase my question. Is it possible to conceive of universes in which this "uncertain physics" does not operate?

If so, how would they look and, perhaps more importantly, how would they differ from ours?

For one thing, the stability of atoms as we know them is due to quantum mechanics; classically the electron should fall into the nucleus. So a classical universe wouldn't have atoms of the sort we have.

 

[Kherubin]

Thank you all for your replies.

Thus, whatever the equations and underscoring metaphysics of some new fangled theory of everything, in some limit (typically at low enough energies and at atomic distances) they must reduce to the equations of quantum mechanics. Why? Because we know quantum mechanics gives the right answer in these cases.

I think I understand why it HAS to operate in our universe given some limiting conditions (low enough energies and at atomic distances), what I fail to grasp is how we can possibly extrapolate this observation beyond our visible universe (in both time and space) and even to OTHER universes.

As an illustrative example, certain cosmologists have posited a quantum fluctuational beginning to our universe, in which the positive energy of matter is counterbalanced by the negative energy of gravity, and Heisenberg's uncertainty principle therefore allows for for the emergence of the entirety of the universe literally 'out of nothing' through a quantum fluctuation.

In this example, I fail to see how quantum principles are applicable even in the very ABSENCE of the universe, to, quite literally, nothing at all.

What precisely is it about the quantum that allows it to lie so low on the scale of that which is important for existence?


Thank you for your time and patience,
Kherubin

 

[computerphys]

That's really just a fancy way of telling us that "philosophy" can't tell us a stinking thing, and is a colossal waste of time.

What a colossal waste of time would be is a universe without observers. To avoid it, quantum uncertainty seems to be a solution.

So, Philosophy is offering a possible answer to the main questions of this thread:

* "Why is quantum so fundamental?": Because it makes consciousness possible.

* "Are non-quantum universes possible?" Yes, possible but non-meaningful.

Philosophy having still not a definite answer to these important questions doesn't mean it is useless. It just means we need to go ahead.

 

[DaveC426913]

What a colossal waste of time would be is a universe without observers. To avoid it, quantum uncertainty seems to be a solution.

How does quantum uncertainty result in observers?

 

[computerphys]

How does quantum uncertainty result in observers?

According to Wikipedia (http://en.wikipedia.org/wiki/Consciousness): "Some theorists—most of whom are physicists—have argued that classical physics is intrinsically incapable of explaining the holistic aspects of consciousness, but that quantum theory provides the missing ingredients."

So (it is reasonable to consider the option that) without uncertainty there is no consciousness, and without consciousness there is no observer, at least the kind of observer that makes a difference between a meaningless universe (a colossal waste of time) and a universe with any warranty of existence (a one with a conscience saying "I think, therefore I exist").

This is not how quantum uncertainty results in observers, but how it is not possible for a purely deterministic universe to have conscious observers.

 

[DaveC426913]

According to Wikipedia (http://en.wikipedia.org/wiki/Consciousness): "Some theorists—most of whom are physicists—have argued that classical physics is intrinsically incapable of explaining the holistic aspects of consciousness, but that quantum theory provides the missing ingredients."

So (it is reasonable to consider the option that) without uncertainty there is no consciousness, and without consciousness there is no observer, at least the kind of observer that makes a difference between a meaningless universe (a colossal waste of time) and a universe with any warranty of existence (a one with a conscience saying "I think, therefore I exist").

This is not how quantum uncertainty results in observers, but how it is not possible for a purely deterministic universe to have conscious observers.

That's what I thought you meant.

 

[ThomasT]

My questions is, why does the quantum, to coin a term, 'subsede' all these other theories?

That is to say, why (and how) is it written into the cosmic underpinnings that even theories as 'fundamental' as string theory have to adopt a quantum nature?

Because, apparently, Planck's constant, h, the quantum of action, is a fundamental physical fact of our universe -- more fundamental than 'strings' or any other mathematical construction being explored as a possible basis for modelling fundamental physical processes. A consequence of the existence of h is the uncertainty relations.

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

Well, given the success of quantum theory, and the apparent correctness of the quantum hypothesis, why would one want to entertain the idea that the quantum of action isn't a fact of nature? I'm not sure what you mean by "continuous, analog universes", but if you're referring to a fundamental ontological contiguity (ie., that, say, the fundamental medium of our universe is absolutely continuous and nonparticulate) then quantization isn't opposed to that. Quantization has to do with behavior, where allowable energy levels or resonances are determined by certain proportionality constants such as Planck's constant -- all of which serves to support the inference that our universe is governed by wave mechanics, and that, say, the string theoretic approach might eventually be developed into a viable unifying framework.

I think I understand why it HAS to operate in our universe given some limiting conditions (low enough energies and at atomic distances), what I fail to grasp is how we can possibly extrapolate this observation beyond our visible universe (in both time and space) and even to OTHER universes.

As an illustrative example, certain cosmologists have posited a quantum fluctuational beginning to our universe, in which the positive energy of matter is counterbalanced by the negative energy of gravity, and Heisenberg's uncertainty principle therefore allows for the emergence of the entirety of the universe literally 'out of nothing' through a quantum fluctuation.

In this example, I fail to see how quantum principles are applicable even in the very ABSENCE of the universe, to, quite literally, nothing at all.

I'm not very well read on this, but in lieu of other suggestions you might check out Heisenberg's "The Physical Principles of the Quantum Theory". You can get a nice Dover edition of it for a couple of dollars at Amazon.

What precisely is it about the quantum that allows it to lie so low on the scale of that which is important for existence?

Well, assuming that our universe is governed by wave mechanics, and that Planck's constant is indeed a fact of nature, then there you have it. Why things happen to be that way is beyond the scope of physics.

Like, I'm betting that eventually physics will postulate a fundamental wave dynamic which describes the observed arrow(s) of time. Will there be any way to go beyond that to say why? Why is the universe expanding? There won't be any way to explore why certain things are, or at least appear to be, fundamental facts of nature. They'll simply be incorporated into a unifying TOE as fundamental dynamical laws, or maybe not ... who knows.

------------------------------------------------------

According to Wikipedia (http://en.wikipedia.org/wiki/Consciousness): "Some theorists—most of whom are physicists—have argued that classical physics is intrinsically incapable of explaining the holistic aspects of consciousness, but that quantum theory provides the missing ingredients."

So (it is reasonable to consider the option that) without uncertainty there is no consciousness, and without consciousness there is no observer, at least the kind of observer that makes a difference between a meaningless universe (a colossal waste of time) and a universe with any warranty of existence (a one with a conscience saying "I think, therefore I exist").

This is not how quantum uncertainty results in observers, but how it is not possible for a purely deterministic universe to have conscious observers.

The fact that there are uncertainty relations due to the assumption of a quantum of action doesn't rule out a deterministic universe with conscious observers. In fact, that's exactly the sort of universe that the extant physical evidence suggests we inhabit. So, I would question the validity of saying that quantum uncertainty is necessary for the emergence of consciousness.

I don't know what the "holistic aspects of consciousness" refers to exactly, but are you willing to consider the possibility that it isn't quantum uncertainty that is the salient precursor to the development of consciousness -- keeping in mind that quantum uncertainty is operational at a scale orders of magnitude removed from the neurological analogs of consciousness? I think it's more likely that they're representatives of two organizational regimes that are more or less isolated from each other.

 

[Varon]

I have recently been reading some of the slew of additions to the genre of layman's cosmology detailing the possibility of one (if not many!) multiverse theories. The books that I have read (including Greene's and Barrowman's) have been truly informative and I highly recommend them.

I am, however, left with one question.

Every time the authors deal with processes seemingly 'fundamental' to the evolution of their multiverse, be that inflating bubbles adopting particular vacuum energies according to quantum principles, or the quantum tunneling of universes between distinct valleys in the string landscape, they appear, still, to operate on the basis of quantum rules.

My questions is, why does the quantum, to coin a term, 'subsede' all these other theories?

That is to say, why (and how) is it written into the cosmic underpinnings that even theories as 'fundamental' as string theory have to adopt a quantum nature?

Further to this, are non-quantized, continuous, analog universes possible, even in principle?

Also don't forget about Ultraviolet Catastrophe. If the laws of physics are continuous. Even the hot coffee sitting on your table can give you sunburn and may even fry you. It's not called Ultraviolet Catastrophe for nothing. So maybe why quantum supersede all theories is so that lowest entropy self assembling ultimate units can exist.

 

[computerphys]

Why things happen to be that way is beyond the scope of physics.

Yes, I agree. When answering this kind of questions, Science is just a set of constrains to what we can say or not properly. Logic is the only tool we have to find out any conclusion. This is Philosophy.

I would question the validity of saying that quantum uncertainty is necessary for the emergence of consciousness.

Wikipedia probably explains it better than I could: http://en.wikipedia.org/wiki/Quantum_mind

FWIW, my preferred point of view is something close to Roger Penrose's.

The very fact that human beings are capable of generating random numbers, but deterministic machines (Touring/algorithms) are not, should be taken seriously into account.

quantum uncertainty is operational at a scale orders of magnitude removed from the neurological analogs of consciousness

Engel et al. (2007) have demonstrated the existence of functional quantum coherence in photosynthetic protein at room temperatures.

 

[ThomasT]

Yes, I agree. When answering this kind of questions, Science is just a set of constrains to what we can say or not properly. Logic is the only tool we have to find out any conclusion. This is Philosophy.




Wikipedia probably explains it better than I could: http://en.wikipedia.org/wiki/Quantum_mind

FWIW, my preferred point of view is something close to Roger Penrose's.

The very fact that human beings are capable of generating random numbers, but deterministic machines (Touring/algorithms) are not, should be taken seriously into account.




Engel et al. (2007) have demonstrated the existence of functional quantum coherence in photosynthetic protein at room temperatures.

Thanks for the reply. It appears that I have some reading to do.

 

[maverick_starstrider]

Yes, I agree. When answering this kind of questions, Science is just a set of constrains to what we can say or not properly. Logic is the only tool we have to find out any conclusion. This is Philosophy.




Wikipedia probably explains it better than I could: http://en.wikipedia.org/wiki/Quantum_mind

FWIW, my preferred point of view is something close to Roger Penrose's.

The very fact that human beings are capable of generating random numbers, but deterministic machines (Touring/algorithms) are not, should be taken seriously into account.




Engel et al. (2007) have demonstrated the existence of functional quantum coherence in photosynthetic protein at room temperatures.

Humans most certainly can't generate random numbers, in fact groupings of "random" numbers are often a method used in forensic accounting. We tend to make up numbers poorly and that can show up when we cook the books and such.

Also, again you're holding up philosophy as something that supersedes science rather than, the previously stated, colossal waste of time.

Postulating on the necessary CONDITIONS for consciousness (and these postulations are of course always done by those who have no clue about the actual science of the mind) is a pointless errand since there exists no objective DEFINITION of consciousness. It's putting the cart before the horse and trying to gallop away. Now where is the only place a useful objective criteria could come from? Philosophy? Hells no. From neurology, the study of A.I., fMRI studies, etc. Computer Science and Biology. In a word: science.

Saying that quantumness is a necessary component for consciousness is silly for two reasons (silly in the "not even wrong" sense, it's a non-starter, it's asking for an answer without even having a question):

1) "Quantumness" is a WORD, in physics we usually use it to denote some shared property of certain mathematical descriptions of reality but it's pretty vague. What makes a theory "quantum"? Is it space quantization? Time? Doubly Special? The non-commutation of linear operators in a Hilbert Space? Is it a wave theory; a probabilistic theory (not all interpretations of quantum require it to be probabilistic, does your argument or quantum=consciousness fall apart in these interpretations?); is it some canonical quantization of a given Lagrangian? But which Lagrangian? Which subsets of Lagrangians is it believed are sufficient for a "conscious observer"? Physics is applied math. It is a quantitative mathematical theory. The problem with science popularizer stuff like Greene and Penrose and such is that it gives the impression that a qualitative discussion, avoiding essentially any detail, is even close to sufficient to extrapolate or interpolate understanding. This is why quantum mechanics always has this cloud of arm-chair "metaphysicists"/mystics going on and on about new age religious garbage. If you can't write your idea down in a concrete, mathematical fashion, from which accurate experimental predictions can be extrapolated, then it's not worth the paper it's not written on.

2) Assuming that our universe/world has the special, unique ingredients to form life/consciousness is an unmotivated fallacy (i.e. human brains work through quantum, therefore quantum must be essential to consciousness). It's thinking in reverse. There's no reason to suspect that from a different universe, with different laws something that we would all agree is consciousness would emerge. How could you possible PROVE that a deterministic computer algorithm could not create "true" "consciousness" (again an issue of definition/semantics). The problem with these sorts of arguments is that right out of the gate they get bogged down with some mumbo-jumbo mysticism about humans having "free will", this ephemeral undefinable quantity that can never be demonstrated or proven that DEMANDS that we not be deterministic at some level. After that first assumption you can basically tune out everything past that. It's an untestable assumption. If it were testable it would be in the purview of science, if it's not it's something "philosophers" yell past each other about, as if they were trying to come to some "agreement" and as if such an "agreement" could actually tell us diddly-squat about life, the universe and everything. It's like Nature vs. Nurture. Every day biologist and computer scientists/mathematicians are closing in on the exact extent to which genetics informs the human experience and to what extent environment does (and to what extent environment potentially effects genetics). There's still an enormous amount of work to be done but at least one thing is clear: it's a bit of both, but genetics seems to be winning. You then flip through a "philosophy journal" and you'll find "papers" written last week about Descartes this, Locke that, tabula rasa this, innatism that. Centuries old "debates", long since resolved (in the sense that we're damn sure they were all wrong). "Free will" is a phrase, it's not an exact concrete quantity, by extension "consciousness" is then just a word, an english word. If there's nothing pertinent to reality that can DEMONSTRATE, concretely, a distinction between a state of consciousness and non-consciousness then there's really nothing to be said at all. It's really that simple. To invoke Mermin again: "Just shut up and calculate".

 

[maverick_starstrider]

It's possible the quantum nature may be so in order that information are discrete (and not continuous) so it can be modeled by 0 and 1 and pixelized and processed.

The problem is that, provided certain parts of the math are linear, there's often not really a difference in predictions between a continuous theory and a theory which is discrete but the little discrete packets are much smaller than your current experimental resolution. That's why we're always trying to look deeper; to higher energies and smaller length-scales.

 

[maverick_starstrider]

Thank you all for your replies.
I think I understand why it HAS to operate in our universe given some limiting conditions (low enough energies and at atomic distances), what I fail to grasp is how we can possibly extrapolate this observation beyond our visible universe (in both time and space) and even to OTHER universes.

As an illustrative example, certain cosmologists have posited a quantum fluctuational beginning to our universe, in which the positive energy of matter is counterbalanced by the negative energy of gravity, and Heisenberg's uncertainty principle therefore allows for for the emergence of the entirety of the universe literally 'out of nothing' through a quantum fluctuation.

In this example, I fail to see how quantum principles are applicable even in the very ABSENCE of the universe, to, quite literally, nothing at all.

What precisely is it about the quantum that allows it to lie so low on the scale of that which is important for existence?Thank you for your time and patience,
Kherubin

I wouldn't spend too much time thinking about such things. The problem is that you can hide all kinds of exotic possibilities outside the realm of current experimental resolution. It seems that the science popularizer industry has gotten to a place where the more outlandish (or the more connected to Star Trek, not knocking star trek there, just saying) the theory, the better. It makes for a nice CGI cover of some colorful swirling blob thing that's supposed to be some N-dimensional field theory or some such. You'll notice that things like Scientific American will somehow have a new crazy theory featured every month. Apparently all of physics is in some enormous uproar and state of constant fluctuation. This is in fact a bunch of bull (I know, I know, I was sad too when I found out, quantum teleportation experiment? Nothing like those books/magazines would like you to think. Invisibility cloaks/metamaterial? So misrepresented it'd just be quicker to call them fiction. Flying cars? Force fields? Phasers? Exactly what law of physics would such a thing operate on?).

The reality is that I'd assume there are an INFINITE number of mathematical equations/theories that you can write down that, in the appropriate limit (low enough energies/large enough length scales) reduce to the equations of the standard model. Here's the rub. You don't actually know ANYTHING new about the universe until you can get one that makes a prediction that is DIFFERENT than the standard model that WE CAN TEST. See of these infinite possible theories/equations I'm sure there are some tame ones, some pretty wild ones, some mind-bending ones. The problem is that things like Sci Am just choose which one they think will sell the most magazines and showcase it as "the new theory that physicists (i.e. this on guy we found) think describes the universe.. blah blah blah 12414 dimensions! holograms! blipity-bop-ons! Is the universe like a jelly donut? Find out. buy! buy! buy!". This of course is news to the 99.9999999% of physicists who aren't the one guy who's just starting tinkering with the idea and hasn't been able to actually crack any of the important integrals. If that fails they'll just go for a theory with a human interest angle: "Surfer baffles physicists with his amazing new theory of everything! It makes no predictions and all of its math is, as of yet, unsolvable! It must be right!", "Rogue physicist shows up her colleagues with crazy untestable theory! (which is disproven a week later, approximately one week and a day after it was originally thought up) Why is this news! Because it's a woman and she's kinda attractive! You know, in that girl next door sort of way!".

The truth is any claim a given theory may make (no matter how awesome) is meaningless until it can distinguish itself from another Standard Model extension with terms added arbitrarily so long as they're too small to detect experimentally. You can hide a whole lot as long as it's well outside the realms of testability, but that's no reason to ASSUME that "there be dragons" (and by dragons I mean what ever outlandish thing is on the cover of Sci Am next month). The actual state of physics and what Greene, Hawking, Michio, Randall, Penrose, Smolin, etc. SELL to the public are two very different things. For example, I'm sure the vast majority of people on the street think someone like Stephen Hawking is the greatest living physicist. Just this power-house of physics and everyone else is just hoping to keep up. I know someone who actually knows more about this is probably going to contradict me on this but I don't know of a single prediction of Hawking's that's actually been verified. As it stands his total contribution, (again I believe, this is really far from my field) is a big fat zero. Now I'm not saying he's not a good physicist I'm just saying he's famous for his disability and his popularizer books, not for some fictitious all consuming research output. I doubt there's a chance in hell he'll ever see something like a Nobel Prize or some such.

 

[computerphys]

Humans most certainly can't generate random numbers, in fact groupings of "random" numbers are often a method used in forensic accounting. We tend to make up numbers poorly and that can show up when we cook the books and such.

This just proofs that random numbers generated by humans are biased. And I agree with you, they are biased. But they are still random.

As stated at http://en.wikipedia.org/wiki/Randomness "randomness implies a lack of predictability" and that is why human being can generate random numbers (biased or not). Otherwise we would be predictable machines. Are you a predictable machine?

Also, again you're holding up philosophy as something that supersedes science rather than, the previously stated, colossal waste of time.

Supersede is not the verb. Philosophy (pure logic) can give us some interesting answers that Science (logic+empiricism) cannot. That's all.

 

[Kherubin]

Thank you again for your replies. The discussion has become very informative, even if a great deal of it is going over my quantized, yet borderline deterministic, free-will-inducing head!

I know some of this is bordering on the philosophical, and I apologize if the mere mention of the word is disconcerting for you, but I AM profoundly interested in what others have to say on the matter.

You can hide a whole lot as long as it's well outside the realms of testability, but that's no reason to ASSUME that "there be dragons"

This is just it! I wonder why the proponents of these theories and the writers of these books ASSUME the potency of quantum mechanics well beyond the temporal and spatial extent of our universe and even into the foundations of theories that currently lie outside our capacity to test. Is there genuinely no reason other than sales figures?



Regarding my second question about non-discrete universes, I now concede it was clumsily phrased. The question, in actuality, had a fairly simple purpose.

The singular point I was making was that if we can conceive of universes which do not abide by the principles of quantum mechanics and these universes are wholly self-consistent, then why is it that it is ASSUMED that the quantum takes precedence?

 

[maverick_starstrider]

I know some of this is bordering on the philosophical, and I apologize if the mere mention of the word is disconcerting for you, but I AM profoundly interested in what others have to say on the matter.

I can see that, which is certainly a good thing (and is why I'm taking the time to answer your questions to the best of my ability).

This is just it! I wonder why the proponents of these theories and the writers of these books ASSUME the potency of quantum mechanics well beyond the temporal and spatial extent of our universe and even into the foundations of theories that currently lie outside our capacity to test. Is there genuinely no reason other than sales figures?

I'm certainly not saying these people are bad physicists. As long as there's no reason to discount a GUT (grand unified theory) it probably deserves some consideration (again, not my field). However, prudence would suggest that you wait until you've actually found something of any note before you run to the presses, sadly prudence is usually ignored.

Regarding my second question about non-discrete universes, I now concede it was clumsily phrased. The question, in actuality, had a fairly simple purpose.

The singular point I was making was that if we can conceive of universes which do not abide by the principles of quantum mechanics and these universes are wholly self-consistent, then why is it that it is ASSUMED that the quantum takes precedence?

Without knowing what theories you're referring to in particular I can't really comment (and even if you did, again not my field). However, there are a large number of experimental/arbitrary constants that define our universe. I think it's a pretty interesting question to consider how physics would play out should these constants have different values (but the rules remain the same) and this may be what you're referring to. In that case you HAVE the rules and it's just the conditions that change (like a game of chess where the pieces don't start in the normal spots, you can still, of course, play the game though). If that's not what you're talking about then I don't know. Any talk of "different universes" can mean some very different things. I'm assuming that you mean it as a hypothetical exercise (an "if things were different what would things be like..." type question). If you're actually referring to some multiverse type deally I'd lump that in with the "don't spend too much time thinking about it". My sense has been that all these mind blowing higher-dimensional/colliding brane/arrow of time type GUTs ultimately boil down to some person who has some expression that reduces to a QFT (quantum field theory) in some limit and then he takes that expression and tries to calculate something... and he gets nowhere, and from that you get a Sci Am cover. It's the same with current favorite string theory. The way the media tells it you'd think it was a bunch of physicists sitting around (presumably smoking a joint) going "woah man, like, what if the world was like.. like, just strings man... strings" and the other guys like "oh. man. that would be awesome!". In reality it all boils down to some guy who noticed a similarity between the behaviour of the strong force and a mathematical expression called the beta function. Which then prompts the question of what is the physical interpretation of the beta function and someone (I feel like it was Susskind) realized that it mapped to a situation of a lattice of 1-dimensional oscillators. And then, skipping ahead, two shifts in calculational paradigms (which has been so modestly called the "first" and "second" "string revolutions"), string theory has yet to come up with a single, experimentally realizable, correction to the QFT we already had. So for all the mind bending claims, what has string theory ACTUALLY told us about the world around us? Not a damn thing.

 

[mjacobsca]

Ah, thank you. Very well then, perhaps I should rephrase my question. Is it possible to conceive of universes in which this "uncertain physics" does not operate?

If so, how would they look and, perhaps more importantly, how would they differ from ours?

There's one key factor that hasn't been touched on, and it's the fact that without quantum fluctuations, we end up with a completely homogenous universe with no variations (e.g. gravity has nothing to work with). Quantum fluctuations present during the Big Bang are responsible for creating different densities in the initial distribution of matter throughout the universe. During inflation, these minuscule fluctuations were inflated to the size of galactic clusters, and within these, additional variations the sizes of galaxies and perhaps even smaller. Gravity was therefore able to take advantage of these differing regions and separate matter into clusters, galaxies, clouds, and stars. Without initial quantum fluctuations, none of this is possible. We end up with a perfect distribution of matter across the entire universe. That concept is almost as unfathomable to me as infinity!

 

[Kherubin]

Without knowing what theories you're referring to in particular I can't really comment

If you're asking about which theories consider 'non-quantum' universes, then I'm afraid my physical knowledge is not deep enough to help you. That's why I sought out the help of better brains than mine!

If, instead, you're talking about exotic theories theories that make use of quantum mechanical effects, I'm talking about the things I've mentioned in my other posts, such as:

1)Our entire universe being a quantum fluctuation out of nothing,

2) Interpretations of inflationary theory in which a quantum fluctuation determines the particular state that the vacuum energy takes when an inflationary bubble 'falls' into it

and

3) The possibility of parts of the universe altering their very own physical 'constants' you speak of, due to a quantum fluctuation whisking them away to a different part of the string landscape


I grasp that these concepts are exotic at best and become more tenuous as we go down the list, I just wondered if there is any current PHYSICAL basis for assuming them to be the case.

It's possible the quantum nature may be so in order that information are discrete (and not continuous) so it can be modeled by 0 and 1 and pixelized and processed.

We're therefore in a computer simulation?!

There's one key factor that hasn't been touched on, and it's the fact that without quantum fluctuations, we end up with a completely homogenous universe with no variations (e.g. gravity has nothing to work with)

I hadn't even thought about that mjacobsca! I suppose for a non-quantum, gravitationally-bound universe to develop complexity requires rather non-homogeneous beginnings?

 

[billschnieder]

Yes. The key property of "quantization" is not that physical values appear in "quanta" (sometimes they don't). The key property is the uncertainty principle, which says that certain pairs of quantities (e.g. position AND momentum) cannot be simultaneously measured.

Instead of calling it "quantum physics" perhaps we should call it "uncertain physics". But the name is stuck, so ...

About the inability to measure quantities simultaneously, consider a simple orthonormal coordinate system with basis vector(a,b,c), where A, B, C correspond to lengths along each direction of the basis vectors. Will you say this is a quantum system? Systems like these abound in classical physics.

Now would you say it is possible to "simultaneously measure" the A,B,C component lengths of an arbitrary vector in this coordinate system? I would think not.

What I am getting at, is that the "uncertainty" has nothing to do with the physics but with how we have chosen to define our "quantities". Position and Momentum are perhaps not two different fundamental quantities but the same fundamental quantity being revealed in two different ways.