Time is the fourth dimension in PHYSICS, not our universe

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Time is the fourth dimension in PHYSICS, not our universe

Post by VikingBoyBilly » Fri Apr 24, 2015 16:32

It's laid out in one simple sentance right here:

http://en.wikipedia.org/wiki/Dimension# ... dimensions
In physics, three dimensions of space and one of time is the accepted norm.
This means that time is just being used as a dimension in FORMULAS to calculate things like distance, speed, acceleration, change, etc. of an object in the three dimensions of space.

It does not mean "oh, hey, you can time travel if you insert a date in the fourth dimension here and zap there. Pretty cool, huh? Also you can create funny paradoxes by playing around with it."

This has to be the biggest misconception of a scientific concept since... uh... I don't know, something else extremely cool and stupid at the same time.

Now this is the fourth dimension of space. :dopekeen
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Post by Roobar » Fri Apr 24, 2015 18:08

In order to prove that, we need to prove that E = mc2 is wrong. And there's where the string theory comes. The universe in a nutshell.

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Post by MoffD » Fri Apr 24, 2015 20:53

I just find myself having to specify the 4th spacial dimension when talking about such things. I still wish people would use this concept more in gaming, right now I'm waiting for miegakure to be finished
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Post by Lava89 » Sat Apr 25, 2015 4:35

Thanks for posting this! As a student in math, it always bugged me that people treat Time like it's Depth or Width. I always preferred to separate time and spatial dimensions.

I also always hate it in sci-fi stories when they say an alien is from a different "dimension" (I'm looking at you...Indy 4!). They can't use different timeline or universe?

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Post by KeenEmpire » Sat Apr 25, 2015 6:08

Lava89 wrote:Thanks for posting this! As a student in math, it always bugged me that people treat Time like it's Depth or Width. I always preferred to separate time and spatial dimensions.
Check out Fine Structure.

(Reader's note: I skipped the first chapter until there was enough context to understand it, around "Sundown".)
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Post by candyjack » Sat Apr 25, 2015 6:45

Physics has always attempted to change the meaning of words as our knowledge of the world increased. The word 'black' originally referred to a very dark colour. Scientists treated it as the absolute lack of colour, a surface that reflects all of the light that lands on it. When it later turned out that such a surface is physically impossible and that you can only approach this effect, they were forced to say that "a truly black surface doesn't exist," even though 'truly black' refers to the definition they themselves imposed.

It's the same story with atoms, which literally means "indivisible particle." The existence of it was first hypothesized by Leucippus and Democritus, and when scientists first observed a very small particle (which they believed was indivisible), they immediately called it atom, paying homage to the Greeks. It later turned out even those particles are divisible, but the name remains unchanged.

Nowadays there even are cosmologists (most notably Lawrence Krauss) who claim that "the universe came forth out of nothing." Not only do they claim that you can go from nothing to something; they claim that this necessarily happens. The basis for this is that, when observing a volume of space that is an absolute vacuum (i.e. there are no particles in this space), it turns out that even then particles arise and disappear in this space, seemingly out of nowhere. This may seem counterintuitive, but it really is a property of physical space, a phenomenon called quantum fluctuation. From what I understand, it's hypothesized that this principle is what originally caused the emergence of the universe. But what is ignored is that 'nothing' in physics stopped reflecting how people originally and intuitively used that word the moment quantum fluctuation was discovered. 'Something out of nothing' is possible, they argue, because of the laws of nature, but those laws are something unto themselves and real 'nothingness' would exclude the existence of even those laws.

So it is with the idea of time as a dimension. Physicists discover that certain calculations are easier when time is defined in such and such a way, and thus they try to impose that change in definition even on the domains of philosophy and linguistics, even though those domains are more fundamental.

However, I do not agree that this fact is the cause of popular culture's reflection of time travel. You could call time something other than a dimension, and things like TARDIS would probably still work in the same way.
Lava89 wrote:I also always hate it in sci-fi stories when they say an alien is from a different "dimension" (I'm looking at you...Indy 4!). They can't use different timeline or universe?
The term 'timeline' relies on the incorrect assumption that it has to do with time, and that use of the word 'universe' outright clashes with its etymology. There can, by very definition, not be more than one universe, nor can there be anything outside it. Perhaps 'plane' would be a better word.
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Post by VikingBoyBilly » Sat Apr 25, 2015 12:28

Or, as in Marathon, they went to another polygon.

As far as I remember from the movie, Indiana never called it any of those words. He just said they went into a space in between spaces, or something like that.
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Post by GoldenRishi » Sun Apr 26, 2015 19:59

Speaking as a physics grad student who studies Quantum Field Theory (what happens when you unify Quantum Mechanics and Special Relativity into a single consistent framework) and General Relativity (what happens when you unify gravity and Relativity into a consistent, non-quantum theory), I'm going to correct some of the claims being made on here. I may not be clear enough, so please ask questions. If people want to argue points, I enjoy that, too, just do me a favor:

If your perspective (I'm not saying anyone here has this or is giving me this impression, but I've discussed this with a lot of people) is that scientists are wrong or stupid and just don't understand, and you have no real interest in changing your mind on this point or you are unwilling to cordially discuss this (even if you won't agree), then I would kindly ask you to politely say "Well, Rishi, I see what you're saying, but I don't agree and I likely never will." and leave it at that.
VikingBoyBilly wrote:It's laid out in one simple sentance right here:

http://en.wikipedia.org/wiki/Dimension# ... dimensions

[indent]"In physics, three dimensions of space and one of time is the accepted norm."[/indent]

This means that time is just being used as a dimension in FORMULAS to calculate things like distance, speed, acceleration, change, etc. of an object in the three dimensions of space.

It does not mean "oh, hey, you can time travel if you insert a date in the fourth dimension here and zap there. Pretty cool, huh? Also you can create funny paradoxes by playing around with it."

This has to be the biggest misconception of a scientific concept since... uh... I don't know, something else extremely cool and stupid at the same time.

Now this is the fourth dimension of space. :dopekeen
This is a misunderstanding of why time is a different kind of dimension than space, not that time isn't a dimension. Mathematically, it is definitely a "dimension", and that's not really a disputable maths point. Crucially, the Pythagorean theorem (Euclidean inner product or metric) does not apply to it, but a generalization of the Pythagorean theorem holds in Minkowski spacetime, which is the correct description of spacetime at low energies and for weak gravitational fields. But unless you understand advanced linear algebra, this probably isn't necessarily going to make sense, so I'll rephrase it this way:

When you write down a vector describing where in spacetime you sit, then you are specifying three numbers to indicate the spatial point and one number to specify the time. In principle if one could build a machine (though that almost certainly can't happen) that would allow you to input four numbers that was the current point in space and the current time that you're at, then yes, if you plugged in t_now - 5 seconds, you would jump back in time to five seconds ago. However, time travel isn't really a reasonable possibility for a different set of reasons, which has to do with quantum mechanics and the Hawking chronology protection conjecture, which has a lot of non-trivial theoretical support.


However, when people say that it's spacetime and not "space + time", if you're moving at a constant offset speed from someone else, your space and time information gets mixed up from their frame of reference. The best example of this is the relativity of simultaneity. This effect can be demonstrated in the following example: if I take two rockets a thousand meters apart and blast them off at the same time (according to my frame), then according to a car's frame moving velocity v (parallel to the two rockets), one will go off before the other one. This is because the spatial distance between the two rockets in your frame gets mixed up into the temporal periods of the moving car's frame. The effect is not perceptible, however, from the velocities capable of produced by cars. For instance, satellites move 8,000 meters per second around the earth (Which is, needless to say, way faster than any car you've driven), and the difference in the time it between them going off is order .001 nanoseconds, or .00000000001 seconds.

For those who are math majors or have a math degree, Minkowski spacetime does form a vector space and a differentiable manifold with well-formed notions of linear and topological dimension.
wiivn wrote:In order to prove that, we need to prove that E = mc2 is wrong. And there's where the string theory comes. The universe in a nutshell.
Well, "E = mc^2" is actually already false by the time we get into General Relativity (the generalized theory for physics involving strong gravitational fields) so we know that this equation is itself an approximation without any mentioning of String Theory. And we know that General Relativity must also be an approximation to Quantum Gravity. This is where String Theory might come in. With that said, there's a very mild generalization of E = mc^2 for particles which is true (i.e. m \sqrt{ -g_{\mu\nu}u^{\mu}u^{\nu} } = mc^2) that accounts for the corrections that GR introduces. But that formula is less catchy, so people don't discuss it as much. =P

BTW, I might suggest taking Michio Kaku's public presentation skills with a grain of salt. He really likes the sound of his own voice, and doesn't mind saying really ambiguous things because he knows the audience will think he sounds really smart. Sean Carroll is probably the best that I can think of off the top of my head, though Lawrence Krauss is pretty good for any non-quantum gravity issues (i.e. take what he says about String Theory with a grain of salt).
Lava89 wrote:Thanks for posting this! As a student in math, it always bugged me that people treat Time like it's Depth or Width. I always preferred to separate time and spatial dimensions.
But it is depth or width, or at least via a boost, it will turn into depth and width. If you know linear algebra (I don't know how far you're into your math program), you can read the article I gave above from Wikipedia on Minkowski space. A great point here is that if you choose units where the speed of light is "1" (which are the most natural units in Special Relativity), then intervals of time are measured in length scales, such as meters.
candyjack wrote:Nowadays there even are cosmologists (most notably Lawrence Krauss) who claim that "the universe came forth out of nothing." Not only do they claim that you can go from nothing to something; they claim that this necessarily happens. The basis for this is that, when observing a volume of space that is an absolute vacuum (i.e. there are no particles in this space), it turns out that even then particles arise and disappear in this space, seemingly out of nowhere. This may seem counterintuitive, but it really is a property of physical space, a phenomenon called quantum fluctuation. From what I understand, it's hypothesized that this principle is what originally caused the emergence of the universe. But what is ignored is that 'nothing' in physics stopped reflecting how people originally and intuitively used that word the moment quantum fluctuation was discovered. 'Something out of nothing' is possible, they argue, because of the laws of nature, but those laws are something unto themselves and real 'nothingness' would exclude the existence of even those laws.
1.) Lawrence Krauss is referring to what is known as the Hawking-Hartle no-boundary proposal. It uses something in quantum mechanics known as "instanton tunneling" to quantum mechanically tunnel from no spacetime at all (which is a trivial solution to Einstein's equations) to an expanding spacetime (a non-trivial solution to Einstein's equations). The derivation uses something called the mini-superspace approximation, which most cosmologists and quantum gravity experts don't believe is justified and thus the model cannot be relied upon because it's ignoring extremely important physics associated to quantum gravity.

2.) So it's not necessary true. It's not really accepted by almost any cosmologists because of the unjustified approximation that it uses.
candyjack wrote: So it is with the idea of time as a dimension. Physicists discover that certain calculations are easier when time is defined in such and such a way, and thus they try to impose that change in definition even on the domains of philosophy and linguistics, even though those domains are more fundamental.
If you really believe that physicists' are simply defining things to make their calculations easier by defining time this way and that's the end of it, then I strongly suggest that, if you haven't done so already, you should really pick up a book on Special Relativity or read Wikipedia articles on Special Relativity (specifically on time dilation, length contraction, and the simultaneity of relativity). You may disagree with the mainstream scientific community on this, but I feel that if you're going to tell physicists (and indirectly the majority of philosophers) that they're wrong about an issue, you should be aware of the issues present.

Also, it'd be hard to argue that linguistics is more fundamental than physics in terms of reality. Linguistics is a statement about how the human mind organizes information and thinks, which makes it more fundamental in terms how humans are and think, but not more fundamental in terms of objective reality. Philosophy is more fundamental than physics, again, in terms how humans approach questions, but philosophy is not necessarily more fundamental in terms of truth statements. That's an open question in metaphysics and the philosophy of science, but most philosophers are not ignorant of Special Relativity and the vast majority of philosophers accept scientific realism (Question 25).
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Post by candyjack » Mon Apr 27, 2015 12:15

GoldenRishi wrote:
candyjack wrote:Nowadays there even are cosmologists (most notably Lawrence Krauss) who claim that "the universe came forth out of nothing." Not only do they claim that you can go from nothing to something; they claim that this necessarily happens. The basis for this is that, when observing a volume of space that is an absolute vacuum (i.e. there are no particles in this space), it turns out that even then particles arise and disappear in this space, seemingly out of nowhere. This may seem counterintuitive, but it really is a property of physical space, a phenomenon called quantum fluctuation. From what I understand, it's hypothesized that this principle is what originally caused the emergence of the universe. But what is ignored is that 'nothing' in physics stopped reflecting how people originally and intuitively used that word the moment quantum fluctuation was discovered. 'Something out of nothing' is possible, they argue, because of the laws of nature, but those laws are something unto themselves and real 'nothingness' would exclude the existence of even those laws.
1.) Lawrence Krauss is referring to what is known as the Hawking-Hartle no-boundary proposal. It uses something in quantum mechanics known as "instanton tunneling" to quantum mechanically tunnel from no spacetime at all (which is a trivial solution to Einstein's equations) to an expanding spacetime (a non-trivial solution to Einstein's equations). The derivation uses something called the mini-superspace approximation, which most cosmologists and quantum gravity experts don't believe is justified and thus the model cannot be relied upon because it's ignoring extremely important physics associated to quantum gravity.

2.) Also, it's not necessary true. It's not really accepted by almost any cosmologists because of the unjustified approximation that it uses.
Thank you for explaining.

We're clearly in agreement here, but I would just like to expand on what my point was: even if Krauss's theory gained acceptance by the scientific community, the claim that "something can arise from nothing" will always be wrong from a philosophical stance, and such theories will rely on a misconception of what we naturally mean when we say 'nothing'.
GoldenRishi wrote:
candyjack wrote: So it is with the idea of time as a dimension. Physicists discover that certain calculations are easier when time is defined in such and such a way, and thus they try to impose that change in definition even on the domains of philosophy and linguistics, even though those domains are more fundamental.
If you really believe that physicists' are simply defining things to make their calculations easier by defining time this way and that's the end of it, then I strongly suggest that, if you haven't done so already, you should really pick up a book on Special Relativity or read Wikipedia articles on Special Relativity (specifically on time dilation, length contraction, and the simultaneity of relativity). You may disagree with the mainstream scientific community on this, but I feel that if you're going to tell physicists (and indirectly the majority of philosophers) that they're wrong about an issue, you should be aware of the issues present.
My apologies if I have made any premature claims. I do not at all doubt Einstein's theories. My issue is specifically with the idea of time as 'the fourth dimension,' which implies it is a spatial dimension and which violates with what we naturally mean by dimensions based on our intuitive understanding of the three dimensions we're used to.

Again, my issue is purely with definitions, and I'm not debating any established physics. I was under the impression that physicists see time as a dimension which is inherently separate from the spatial dimensions, and that the idea of time as a spatial dimension is simply a misunderstanding. Can you tell me whether or not this is true? Does time, according to established physics, relate to the third dimension as the third dimension relates to the second one?
GoldenRishi wrote: Also, it'd be hard to argue that linguistics is more fundamental than physics in terms of reality. Linguistics is a statement about how the human mind organizes information and thinks, which makes it more fundamental in terms how humans are and think, but not more fundamental in terms of objective reality. Philosophy is more fundamental than physics, again, in terms how humans approach questions, but philosophy is not necessarily more fundamental in terms of truth statements. That's an open question in metaphysics and the philosophy of science, but most philosophers are not ignorant of Special Relativity and the vast majority of philosophers accept scientific realism (Question 25).
I called linguistics more fundamental because it deals with the very thing we use to convey meaning (namely language). However, I have no hard feelings about this, since I've never heard anyone else make this claim, and I don't see of what consequence this matter is either.

I do, however, disagree about as much as the possibility of physics being more fundamental than philosophy (even of truth statements). Modern physics started out as a branch of philosophy for a reason, after all. That claim would mean that philosophical arguments about phenomena such as determinism are affected and proven wrong by findings in physics (in this case in the field of quantum mechanics). Heisenberg's principle would have threatened the philosophical views of thinkers such as Newton and Einstein, and the Bell and Kochen-Specker theorems would have given us absolute certainty that determinism is incorrect. (Nevermind the underlying question of what certainty is in the first place, of course; this is dealt with by epistemology, another field of philosophy.)

Are you defending that view?
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Post by VikingBoyBilly » Mon Apr 27, 2015 13:10

Well, well, Commander Keen and the Grand Intellect have revealed their secret identities on the forum at last! Now the question is which is which? :mort
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Post by GoldenRishi » Mon Apr 27, 2015 16:35

candyjack wrote:
GoldenRishi wrote:1.) Lawrence Krauss is referring to what is known as the Hawking-Hartle no-boundary proposal. It uses something in quantum mechanics known as "instanton tunneling" to quantum mechanically tunnel from no spacetime at all (which is a trivial solution to Einstein's equations) to an expanding spacetime (a non-trivial solution to Einstein's equations). The derivation uses something called the mini-superspace approximation, which most cosmologists and quantum gravity experts don't believe is justified and thus the model cannot be relied upon because it's ignoring extremely important physics associated to quantum gravity.

2.) Also, it's not necessary true. It's not really accepted by almost any cosmologists because of the unjustified approximation that it uses.
Thank you for explaining.

We're clearly in agreement here, but I would just like to expand on what my point was: even if Krauss's theory gained acceptance by the scientific community, the claim that "something can arise from nothing" will always be wrong from a philosophical stance, and such theories will rely on a misconception of what we naturally mean when we say 'nothing'.
I have no objections to this, of course. "Nothing" in the conceptual sense isn't what he's talking about; there isn't a space or a time, but there are still laws that allow you to transfer from nothing spatially/temporally to something with spatial and temporal extent.
candyjack wrote:
GoldenRishi wrote:
candyjack wrote: So it is with the idea of time as a dimension. Physicists discover that certain calculations are easier when time is defined in such and such a way, and thus they try to impose that change in definition even on the domains of philosophy and linguistics, even though those domains are more fundamental.
If you really believe that physicists' are simply defining things to make their calculations easier by defining time this way and that's the end of it, then I strongly suggest that, if you haven't done so already, you should really pick up a book on Special Relativity or read Wikipedia articles on Special Relativity (specifically on time dilation, length contraction, and the simultaneity of relativity). You may disagree with the mainstream scientific community on this, but I feel that if you're going to tell physicists (and indirectly the majority of philosophers) that they're wrong about an issue, you should be aware of the issues present.
My apologies if I have made any premature claims. I do not at all doubt Einstein's theories. My issue is specifically with the idea of time as 'the fourth dimension,' which implies it is a spatial dimension and which violates with what we naturally mean by dimensions based on our intuitive understanding of the three dimensions we're used to.

Again, my issue is purely with definitions, and I'm not debating any established physics. I was under the impression that physicists see time as a dimension which is inherently separate from the spatial dimensions, and that the idea of time as a spatial dimension is simply a misunderstanding. Can you tell me whether or not this is true? Does time, according to established physics, relate to the third dimension as the third dimension relates to the second one?
Yes and no.

1.) I think the confusion here stems from the technical definition(s) of a "dimension" versus the colloquial notion of a "dimension." There are two major definitions of dimensions according to mathematicians, one being called the linear dimension of vector spaces and the other being the topological dimension of topological spaces. The later definition (although time being a dimension conforms to this definition as well) is more complicated and I won't bother to go into it, but I will give a heuristic (not technical) definition of the former notion of dimension. The mathematical notion of dimension (linear dimension) refers to having a list of numbers. In other words, if we want to describe where and when we are in the universe, then you have to setup a coordinate system which assigns every point in space a triple (x,y,z), and if you want to specify when, then you need an additional number for time (t).

2.) So yes, if it were merely this notion of a dimension you might say "So what?" In Newton's conception of the universe, there are two different things. An absolute time, t, which we all agree upon (if it's 3 PM on Tuesday on your watch, then a guy moving 10,000 m/s away from you who has a watch will also read 3 PM on Tuesday) and distances. If you are moving 10,000 m/s away from me, and I measure a board to be 3 meters long, then you'll agree with me that it's 3 meters long. I can talk about things like they're (t,x,y,z), but it's really (t) and (x,y,z), separately. Distances are given by d^2 = x^2 + y^2 + z^2 (Pythagorean Theorem), and time is given by reading off clocks.

3.) What makes Special Relativity's spacetime not simply "Space and time" is that the following equation doesn't work between two moving observers:

d^2 = x^2 + y^2 + z^2

What I mean by this if you're moving 10,000 m/s away from mean, then the d^2 that you get after doing a measurement will not be the same d^2 that I get after I make my measurements. Length is not absolute. It turns out what is absolute, i.e. a quantity that we will agree upon, is the following:

d^2 = - ( c t )^2 + x^2 + y^2 + z^2

Which is Minkowski's correction to the Pythagorean theorem for spacetimes. When we are moving at offset velocities, your space and time gets mixed up into my time, and your space and time gets mixed up into my space. However, they only get mixed up in a such a way that it preserves a Pythagorean-like formula for the geometry of the spacetime.


(And when you get to General Relativity, the mixing of space and time is so thorough, it's not even necessarily possible to uniquely identify one time-like dimension over the entire spacetime)
candyjack wrote:I called linguistics more fundamental because it deals with the very thing we use to convey meaning (namely language). However, I have no hard feelings about this, since I've never heard anyone else make this claim, and I don't see of what consequence this matter is either.
Okay.
candyjack wrote:
GoldenRishi wrote: Philosophy is more fundamental than physics, again, in terms how humans approach questions, but philosophy is not necessarily more fundamental in terms of truth statements. That's an open question in metaphysics and the philosophy of science, but most philosophers are not ignorant of Special Relativity and the vast majority of philosophers accept scientific realism (Question 25).
I do, however, disagree about as much as the possibility of physics being more fundamental than philosophy (even of truth statements). Modern physics started out as a branch of philosophy for a reason, after all. That claim would mean that philosophical arguments about phenomena such as determinism are affected and proven wrong by findings in physics (in this case in the field of quantum mechanics). Heisenberg's principle would have threatened the philosophical views of thinkers such as Newton and Einstein, and the Bell and Kochen-Specker theorems would have given us absolute certainty that determinism is incorrect. (Nevermind the underlying question of what certainty is in the first place, of course; this is dealt with by epistemology, another field of philosophy.)

Are you defending that view?
The view that science has essentially disproven determinism? It depends on what you mean specifically by determinism, because QM and QFT obey a kind of determinism in terms of the evolution of their probability distribution functionals given their initial conditions, but if you mean that the outcomes of specific scenarios are determined identically by what happened previously, then yes, I think that we can be "certain" (in the nuanced sense that you mention above) that determinism is false, and yes, this is something that metaphysicians and philosophers in general must conform to if they want their ideas to be taken seriously, or else they must have some serious justification for why they can neglect what is known experimentally. This hardly seems like a controversial claim ("Philosophies ought to conform to facts of the matter"), given that many philosophers of science, e.g. Daniel Dennett and Massimo Pigliucci, take for granted.


As for the Bell Inequality and the Kochen-Specker theorems, no they are not proofs against determinism, of course, but they add the compounding certainty that determinism is not a tenable position. Technically speaking, there are very old proposals such as Bohmian mechanics which replicates some (it's unknown if it replicates all) of the predictions of QM, but remains deterministic because it contains non-local hidden variables. But it appears to fail to work under any incorporation of relativity, however, and so physicists became very uninterested in it.
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Post by guynietoren » Mon Apr 27, 2015 18:43

I remember reading that a 4th spacial dimension doesn't exist because several current math equations would fail to work if all the dimensions weren't accounted for. Sorry I'm having trouble finding the article again. But it pretty much means that time is a concept and not a plane of existence. Although the rate time passes isn't a constant as much as we want it to be.

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Post by candyjack » Mon Apr 27, 2015 19:20

First of all, I'd like to correct myself. I'm not sure whether or not Newton believed in determinism, but I meant Laplace. However, while we're at it, Spinoza is probably a way better example. Spinoza's Ethica provides an a priori deduction for determinism. The claim that physics is more fundamental than metaphysics implies that the soundness of even those a priori arguments is altered by empirical data, but this is simply not how philosophy works. Empirical data might inspire arguments, but in order to refute Spinoza, you'll have to tackle his arguments.
GoldenRishi wrote:
candyjack wrote:
GoldenRishi wrote: Philosophy is more fundamental than physics, again, in terms how humans approach questions, but philosophy is not necessarily more fundamental in terms of truth statements. That's an open question in metaphysics and the philosophy of science, but most philosophers are not ignorant of Special Relativity and the vast majority of philosophers accept scientific realism (Question 25).
I do, however, disagree about as much as the possibility of physics being more fundamental than philosophy (even of truth statements). Modern physics started out as a branch of philosophy for a reason, after all. That claim would mean that philosophical arguments about phenomena such as determinism are affected and proven wrong by findings in physics (in this case in the field of quantum mechanics). Heisenberg's principle would have threatened the philosophical views of thinkers such as Newton and Einstein, and the Bell and Kochen-Specker theorems would have given us absolute certainty that determinism is incorrect. (Nevermind the underlying question of what certainty is in the first place, of course; this is dealt with by epistemology, another field of philosophy.)

Are you defending that view?
The view that science has essentially disproven determinism? It depends on what you mean specifically by determinism, because QM and QFT obey a kind of determinism in terms of the evolution of their probability distribution functionals given their initial conditions, but if you mean that the outcomes of specific scenarios are determined identically by what happened previously, then yes, I think that we can be "certain" (in the nuanced sense that you mention above) that determinism is false, and yes, this is something that metaphysicians and philosophers in general must conform to if they want their ideas to be taken seriously, or else they must have some serious justification for why they can neglect what is known experimentally. This hardly seems like a controversial claim ("Philosophies ought to conform to facts of the matter"), given that many philosophers of science, e.g. Daniel Dennett and Massimo Pigliucci, take for granted.


As for the Bell Inequality and the Kochen-Specker theorems, no they are not proofs against determinism, of course, but they add the compounding certainty that determinism is not a tenable position. Technically speaking, there are very old proposals such as Bohmian mechanics which replicates some (it's unknown if it replicates all) of the predictions of QM, but remains deterministic because it contains non-local hidden variables. But it appears to fail to work under any incorporation of relativity, however, and so physicists became very uninterested in it.
In response to the findings of Heisenberg and Bohr and the role of randomness it implied, Einstein hypothesized a hidden variable which could be used to predict the wave-function collapse nonetheless, and of which we simply weren't aware. With this as a possibility, determinism still didn't seem disproven. The reason I brought up the Bell and Kochen-Specker theorems is because they seemed to exclude Einstein's hidden variable. And here comes the main issue. If physics is more fundamental than metaphysics, those theorems exclude even the possibility of a variable which remains hidden, and which we'll never be able to measure. In other words: we are to make deductions about the world based on what we can and cannot measure. This relies on the hidden assumption that only that exists which we can measure.

Rather than arguing that this assumption is incorrect, I'm going to take a different approach and say that the very question (i.e. whether or not there can exist more than what we can measure) lies within the boundaries of metaphysics. Thus, in order to argue for how fundamental physics is, one has to rely on metaphysics. It naturally follows that metaphysics is the more fundamental field.
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Post by GoldenRishi » Mon Apr 27, 2015 21:25

candyjack wrote:First of all, I'd like to correct myself. I'm not sure whether or not Newton believed in determinism, but I meant Laplace. However, while we're at it, Spinoza is probably a way better example. Spinoza's Ethica provides an a priori deduction for determinism. The claim that physics is more fundamental than metaphysics implies that the soundness of even those a priori arguments is altered by empirical data, but this is simply not how philosophy works. Empirical data might inspire arguments, but in order to refute Spinoza, you'll have to tackle his arguments.
That depends on what you mean by "refute." If you mean to "refute" in the sense of providing a counter argument to Spinoza's claim that deductively proves Spinoza wrong with a valid polysyllogism, then no, science isn't going to refute Spinoza. That's not the level at which science would attack Spinoza's thesis. But if you mean to question whether or not science can provide enough empirical data so as to make Spinoza's thesis entirely unreasonable in the sense of almost certainly being wrong, then no, I wouldn't, anymore than I'd need to carefully know the arguments of a Biblical literalist's interpretation of the Bible to refute them with the sole knowledge that evolution is true. However, there's two important issues:

1.) There is a caveat, however, which is important for reading Spinoza before declaring him (or anyone else) to be wrong, and that is the issue of how specific Spinoza's definitions might be or how broadly we construe Spinoza's sense of determinism. If Spinoza used the term "determinism" in a more general sense, then perhaps the deterministic evolution of a wavefunction in QM would be sufficient to make his definition of determinism valid. If that's true, then I don't necessarily have anything to say against his argument.

2.) I think this gets back to the what you're really trying to get at, but I tend to reject the notion of a priori synthetic statements. Admittedly my readings of metaphysics have been more limited than many other areas of philosophy, but it seems to me that any claim about the nature of reality that comes from pure thought alone is always suspect. For two thousand years people thought that they might make progress in understanding the world around them in this manner, and for two thousand years they failed. Which is not to say that you can't gain insight into the nature of the world by thinking, but the thinking should at least be tethered to corroborated facts of the matter. If this is what is meant by "inspired", then we're in perfect agreement. But if you mean that we can rationally deduce certain synthetic propositions that can never be rendered false by our experience or by an experiment, then I'm all ears on what such a proposition would look like or how one could rationally deduce it with such certainty. I won't go so far as to say such a thing could never done, but I must admit that I'm nonplussed on how anyone could provide such a justification which didn't amount to it actually being an analytic statement.
candyjack wrote:
GoldenRishi wrote:
candyjack wrote: I do, however, disagree about as much as the possibility of physics being more fundamental than philosophy (even of truth statements). Modern physics started out as a branch of philosophy for a reason, after all. That claim would mean that philosophical arguments about phenomena such as determinism are affected and proven wrong by findings in physics (in this case in the field of quantum mechanics). Heisenberg's principle would have threatened the philosophical views of thinkers such as Newton and Einstein, and the Bell and Kochen-Specker theorems would have given us absolute certainty that determinism is incorrect. (Nevermind the underlying question of what certainty is in the first place, of course; this is dealt with by epistemology, another field of philosophy.)

Are you defending that view?
[...]

As for the Bell Inequality and the Kochen-Specker theorems, no they are not proofs against determinism, of course, but they add the compounding certainty that determinism is not a tenable position. Technically speaking, there are very old proposals such as Bohmian mechanics which replicates some (it's unknown if it replicates all) of the predictions of QM, but remains deterministic because it contains non-local hidden variables. But it appears to fail to work under any incorporation of relativity, however, and so physicists became very uninterested in it.
In response to the findings of Heisenberg and Bohr and the role of randomness it implied, Einstein hypothesized a hidden variable which could be used to predict the wave-function collapse nonetheless, and of which we simply weren't aware. With this as a possibility, determinism still didn't seem disproven. The reason I brought up the Bell and Kochen-Specker theorems is because they seemed to exclude Einstein's hidden variable.
No, they don't disprove them. All theorems start with assumptions, and the theorems are only as wide-ranging as their assumptions are. In the case of the Bell's Equalities and related theorems, they assume:

There is a deterministic theory with local hidden variables.

If so, then Bell's Inequality cannot hold. Thus, given that the experiments corroborate Bell Inequality to probability P (They aren't entirely experimentally proven yet, but for the sake of argument let's say that they were, so that one can be 99.9999999% sure that Bell's Inequalities hold), then the belief that our universe is deterministic and local holds to .00000001%. In other words, it's a very unreasonable belief.

We can't be 100% sure through experiments, but for the sake of the argument, let's suppose that we could be. If so, then we can be 100% sure that determinism with local hidden variables is false. So most people who want to play this game, although it hasn't gotten them anywhere, instead rely on something like Bohmian mechanics, which makes use of non-local hidden variables.
candyjack wrote: And here comes the main issue. If physics is more fundamental than metaphysics, those theorems exclude even the possibility of a variable which remains hidden, and which we'll never be able to measure. In other words: we are to make deductions about the world based on what we can and cannot measure. This relies on the hidden assumption that only that exists which we can measure.
1.) There might be hidden things that we cannot measure that nevertheless are a part of reality, sure. Cro magnon couldn't measure electrons, but electrons certainly existed. The problem is that metaphysicians aren't anymore qualified to talk about them with authority and certainty than physicists are.

2.) No, in this case one is modifying a physical observable, which is the probability distribution functional. Which means that by definition it is observable, because we observe the PDF. Now, you might say that we could have a non-local hidden variable theory which adds an effect that, except for that effect, is like QM in every regard. But this game is harder to play than you think it is. It's easy to say "Look, maybe there's QM (or any scientific theory) plus more things in existence." It's much harder to say "Look, maybe there's QM objects, but there's also something else that exists, and this object interacts with QM objects but cannot be measured." It's essentially an act of self-contradiction to assume the last bit. If it interacts with QM, then it will furnish observable differences from ordinary QM that can in principle be measured. In fact, this is entirely the problem with non-local hidden variables theory: It doesn't provide a way of consistently incorporating the effects of Special Relativity. That means that it can't include Special Relativity without creating predictions that are already known to be wrong.
candyjack wrote:Rather than arguing that this assumption is incorrect, I'm going to take a different approach and say that the very question (i.e. whether or not there can exist more than what we can measure) lies within the boundaries of metaphysics. Thus, in order to argue for how fundamental physics is, one has to rely on metaphysics. It naturally follows that metaphysics is the more fundamental field.
I think you're changing the question. My objection lies mostly with the portion of your claim regarding "even of truth statements", not necessarily with which field is more basic/primitive/fundamental at an assumptions level. The answer to that depends on how you define these things. So if you want to do science, you have to assume a certain kind of metaphysics, then yes you have to assume certain statements about reality. As per above, in order for me to see how it could be true, however, that metaphysics would be more fundamental at a truth-statement level (i.e. metaphysics says X but observation tells us ~X, but we are obliged to conclude X because metaphysics is more fundamental), it seems to hold one-to-one correspondence with providing an a priori synthetic statement. Again, perhaps I'm misunderstanding you and that's not what you mean.

Perhaps you mean that philosophy can point out incorrect thinking of scientists, and that this can have important implications, and in this sense philosophy is more fundamental, including truth statements. Certainly, there's a venerable history in the philosophy of science to support this; of course, failures were also made with, e.g., positivism or mechanism. But if so, then I agree with you. One need look no further than David Hume's discussion of the Problem of Induction, which was completely ignored by physicists/natural philosophers for a century until Newton's laws and Euclidean geometry were falsified (Which prior to this were considered a priori synthetic statements) by Einstein's work and the experiments that later corroborated it. Repeating an experiment doesn't prove that the theoretical model that happens to get the prediction correct is deductively correct, and in fact if one wants to do this correctly one introduces probability theory to account for the problem of induction and one modifies their understanding of what to conclude from scientific experiments and theories. However, none of that seems to support the thesis that science cannot correct or disprove metaphysics or philosophical arguments. Philosophical arguments rely on premises just like everyone else's arguments; if science shows that the premise is wrong (or at least worth questioning), then it seems to me that philosophers have to own up to the failure of their ideas to accord with observation and experience, just like every other discipline does when philosophers point out a flawed or incoherent premise.
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Post by VikingBoyBilly » Mon Apr 27, 2015 23:45

guynietoren wrote:I remember reading that a 4th spacial dimension doesn't exist because several current math equations would fail to work if all the dimensions weren't accounted for. Sorry I'm having trouble finding the article again. But it pretty much means that time is a concept and not a plane of existence. Although the rate time passes isn't a constant as much as we want it to be.
Sure the equations still work, it just means the 4th dimension's value is constant for everything we observe.

Everything displayed on your computer monitor is stuck in a two-dimensional zone. The monitor itself is in a 3 dimensional world. If you move the monitor, everything on the two-dimensional screen remains relative to each other; they technically are moving through the third dimension, but the change can only be noticed if you are looking at it from outside in three dimensional space.

Visualize that we are stuck on a three-dimensional surface where everything is relative to each other in the 4th dimension.
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