Has a surfer Ph.D. rewritten physics? Maybe. • Hacker News Board

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#21

Post by gaika » Sun, Jul 27, 2008, 7:05 PM UTC

brentr wrote: post #11

I don't remember where I read it, nor the exact wording, but there is a quote that is perfect for this. It went something like this, "Godel proved incompleteness. Anyone who thinks there is a theory of everything laughs in the face of Godel." My point is that physics does not exist in a vacuum. It is built up from observational data found in nature and taken from experiments. If mathematics can't come to complete tru…

One counterexample for you: Conway's game of life has finite number of rules but you can construct universal turing machine with it that will have formally undecidable behaviour.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#22

Post by sarehu » Sun, Jul 27, 2008, 7:13 PM UTC

brentr wrote: post #20

sarehu wrote: post #18

Earlier quoted context omitted.

What about it? All Godel's incompleteness theorem says is that there will be open questions about a universe describable by finitely many rules. The laws of physics don't need to provide answers to questions about whether computers in its universe will halt or whether planetary systems are stable.

What do you mean "the laws of physics don't need to provide answers to whether planetary systems are stable"? Since when are planetary systems outside of physics? Your sentence "All Godel's incompleteness theorems says is that there will be open questions about a universe describable by finitely many rules" shows right there that there cannot be a theory of everything. How can you have a theory of everything yet stil…

It's my understanding that a theory of everything describes the rules by which the universe operates. It doesn't say anything about emergent properties of these rules.

For example, if everything in the universe obeyed Newtonian mechanics, I would say that Newtonian mechanics was a theory of everything. You would say that it isn't.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#23

Post by DanielBMarkham » Sun, Jul 27, 2008, 7:53 PM UTC

sarehu wrote: post #14

brentr wrote: post #11

I don't remember where I read it, nor the exact wording, but there is a quote that is perfect for this. It went something like this, "Godel proved incompleteness. Anyone who thinks there is a theory of everything laughs in the face of Godel." My point is that physics does not exist in a vacuum. It is built up from observational data found in nature and taken from experiments. If mathematics can't come to complete tru…

That's complete nonsense. There's nothing about Godel's theorem that says the physical rules of the universe can't be described. You're babbling religiously.

"A small number of scientists claim that Gödel's incompleteness theorem proves that any attempt to construct a TOE is bound to fail. Gödel's theorem states that any non-trivial mathematical theory that has a finite description is either inconsistent or incomplete."

That's from the Wiki, FWIW. I'm not big on using Wiki as a source.

"Babbling religiously" is right on the line in my opinion. It makes you sound like an arrogant jerk. If you have problems with the content of the comment, state your case in neutral terms.

Learn to live with other people's ambiguity and looseness in phrasing. Then perhaps they'll be more forgiving of yours. (Downmod)

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#24

Post by maurycy » Sun, Jul 27, 2008, 9:05 PM UTC

Allocator2008 wrote: post #19

Well leaving aside Godel, I think one can have a theory of everything that has, as Rumsfeld would say, "known unknowns", i.e., a theory of everything which "manages" in some way unknown parameters. Like infinities in quantum field theory go away by the nature of string theory's elimination of arbitrarily small distances. Anyway. I think I'm keeping my money on string theory, but an interesting thought nonetheless!

What a brilliant observation about "known unknowns". Though, one could say that there are also unkown unkowns, and unkown knowns, yet.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#25

Post by DanielBMarkham » Sun, Jul 27, 2008, 9:35 PM UTC

Allocator2008 wrote: post #19

Well leaving aside Godel, I think one can have a theory of everything that has, as Rumsfeld would say, "known unknowns", i.e., a theory of everything which "manages" in some way unknown parameters. Like infinities in quantum field theory go away by the nature of string theory's elimination of arbitrarily small distances. Anyway. I think I'm keeping my money on string theory, but an interesting thought nonetheless!

If you read a bit of Wolfram, he asks a provocative question: suppose the universe is, in fact, discrete and not continuous. If this is the case, and I think that's non-controversial now, then it may be that Sir Newton took us way down the wrong road with his discovery of the integral. We've been doing continuous math-type things with a universe that simply does not work that way. The integral was simply a cheat -- a numbers game that looked as true to reality as we could possibly verify at the time.

So we're working with known unknowns. That is, the integral works so well in most everything we do we're comfortable where it falls apart -- right around ToE, probably. But if we went belly-up as far back as Newton, where to start to fix it? I know I'm sounding like a shill for NKS now, but I _did_ find it had some really interesting ideas. In a computational universe, we could have really simple physics that lead to incredibly complex and non-intuitive results.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#26

Post by mlinsey » Sun, Jul 27, 2008, 9:40 PM UTC

sarehu wrote: post #22

brentr wrote: post #20

Earlier quoted context omitted.

What do you mean "the laws of physics don't need to provide answers to whether planetary systems are stable"? Since when are planetary systems outside of physics? Your sentence "All Godel's incompleteness theorems says is that there will be open questions about a universe describable by finitely many rules" shows right there that there cannot be a theory of everything. How can you have a theory of everything yet stil…

It's my understanding that a theory of everything describes the rules by which the universe operates. It doesn't say anything about emergent properties of these rules. For example, if everything in the universe obeyed Newtonian mechanics, I would say that Newtonian mechanics was a theory of everything. You would say that it isn't.

Technically, a "Theory of Everything" in physics is just a theory that relates the four known forces in the universe: gravity, electromagnatism, strong nuclear, and weak nuclear. The latter three (I believe) have already been unified. It's a "theory of everything" because it describes every force in the universe.

That of course does not imply that the theory of everything automatically gets you a complete description of the universe. Even in the context of a single force, it can be difficult/impossible to come up with a closed form solution for how many different objects interact subject to that force. For example, the behavior of gravity is really well understood but that doesn't mean that we can come up with straightforward, closed form solutions for the n-body problem of a bunch of stars interacting with each other's gravitational pulls in space.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#27

Post by DaniFong » Sun, Jul 27, 2008, 11:37 PM UTC

DanielBMarkham wrote: post #25

Allocator2008 wrote: post #19

Well leaving aside Godel, I think one can have a theory of everything that has, as Rumsfeld would say, "known unknowns", i.e., a theory of everything which "manages" in some way unknown parameters. Like infinities in quantum field theory go away by the nature of string theory's elimination of arbitrarily small distances. Anyway. I think I'm keeping my money on string theory, but an interesting thought nonetheless!

If you read a bit of Wolfram, he asks a provocative question: suppose the universe is, in fact, discrete and not continuous. If this is the case, and I think that's non-controversial now, then it may be that Sir Newton took us way down the wrong road with his discovery of the integral. We've been doing continuous math-type things with a universe that simply does not work that way. The integral was simply a cheat -- a…

I didn't think the question of continuous versus discontinuous universes has ever really been resolved in a convincing way. Do you have any references?

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#28

Post by ninguem1 » Mon, Jul 28, 2008, 12:00 AM UTC

donw wrote: post #2

My knowledge of mathematics is dwarfed by anybody with a higher degree in the subject, and Algebra (the abstract kind, not the kind with lots of letters) was my worst subject, but part of me is a bit pleased that E8 might be related to an important bit of physics. It's a rather interesting structure, although not 'the largest' as the article claims, as there are some which (if I recall correctly), reach into million-…

E8 is an exceptional Lie group (ie a group that is also a manifold, hence in particular infinite). You seem to be mixing it up with the exceptional finite simple groups. Wikipedia explains.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#29

Post by ninguem1 » Mon, Jul 28, 2008, 12:04 AM UTC

brentr wrote: post #11

I don't remember where I read it, nor the exact wording, but there is a quote that is perfect for this. It went something like this, "Godel proved incompleteness. Anyone who thinks there is a theory of everything laughs in the face of Godel." My point is that physics does not exist in a vacuum. It is built up from observational data found in nature and taken from experiments. If mathematics can't come to complete tru…

"Theory of Everything" is not a theory for everything, literally. It is just a catchphrase used by physicists to mean a theory that encompasses the "Standard Model" (which describes particle physics) with General Relativity and gravitation, thus describing the whole physical universe (which, in the physicists narrow mind, is everything). So Godel has nothing to do with this.

Re: Has a surfer Ph.D. rewritten physics? Maybe.

#30

Post by dehowell » Mon, Jul 28, 2008, 12:19 AM UTC

No. Even though particle physics gets all the media attention, theories like this (and string theory for that matter), are shallow in comparison to statistical mechanics and thermodynamics.

It's exciting to find out what the smallest building blocks look like, but all the real structure in the universe arise from the interactions... and statistical mechanics addresses the interactions at all scales.

Modifications to our understanding of the smallest scales will trickle up to stat mech and thermo, but statistical mechanics is the true heart of physics.