Got asked, "Why does there 'need' to be a UFT"

  • Context: Graduate 
  • Thread starter Thread starter Cake
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around the question of why there is a perceived need for a unified field theory (UFT) that integrates all four fundamental forces of the universe. Participants explore the philosophical and scientific implications of seeking such a theory, touching on the motivations behind theoretical unification and the nature of mathematical constructs in physics.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants suggest that the logical and predictable nature of the universe implies a potential for unification of forces, though this does not necessarily mean a UFT is required.
  • Others argue that the pursuit of a UFT may stem from a human desire for simplicity and coherence in understanding the universe, rather than a necessity dictated by nature.
  • One participant notes that many physicists, including Stephen Hawking, do not believe a Theory of Everything is necessarily achievable or even existent.
  • There is a viewpoint that the assumption of a UFT is naive and based on faith rather than empirical evidence, emphasizing that mathematics provides approximations rather than absolute laws.
  • Some participants highlight the importance of developing a quantum theory of gravitation, with string theory mentioned as a candidate for unification, though it is noted that this is speculative and not a definitive goal of modern physics.
  • Concerns are raised about misconceptions propagated by popular science regarding the existence of gaps in our understanding that a UFT would fill.
  • Discussion includes a critique of a mathematics graduate student's skepticism about the utility of tensors in physics, with some participants defending the mathematical foundations of physics as being motivated by nature.

Areas of Agreement / Disagreement

Participants express a range of views on the necessity and existence of a UFT, with no consensus reached. Some believe in the potential for unification, while others are skeptical about its feasibility or necessity.

Contextual Notes

Participants acknowledge that the discussion involves complex philosophical and scientific considerations, with various assumptions about the nature of mathematical models and their relationship to physical reality remaining unresolved.

  • #31
sophiecentaur said:
But this process has been subjected to a series of significant hiccups and changes of direction. One could say that things have ended up as they are in a form of logical progression but that's more a statement of faith than evidence based. As far as I can se, all we can expect is a series of 'Theories of Most things we know about". I have no problem with accepting that we cannot expect to know it all. Indeed, it seems a ludicrous notion - bordering on religion (which is equally badly founded).
My Dad was quite knowledgeable for my purposes when I was a lad and I don't feel the need to replace him with a more and more super-Dad to explain all I would ever want to know.

That is why I don't like the phrase "Theory of Everything." There are things in the world that can never be understood, like beauty, because beauty is not in the field of consciousness or within the grasp of thought. However my notion of quantum gravity is not a "theory of everything."

If theoretical physics is like a story, then quantum gravity is like the climax of the story. Or if you think of physics as sex, then quantum gravity is the orgasm. (Moderators feel free to delete that last part if you think its inappropriate)
 
Physics news on Phys.org
  • #32
mattt said:
There are several mathematical theorems about that subject. "Willing to accept" seems a very odd way of saying "they know some mathematical theorems".
When you accept even simple mathematics (2+2=4) , you get Godel's proof along with it. Most of the time you can kick it into a corner and ignore it. Other times, it is in your face. I remember a time when studying the strong force meant dealing with infinities. Fortunately renormalization came along and pushed those infinities back into the dusty corners. But with general relativity, there are still infinities, and they are in the black holes that are all over the place. (On a stellar scale at least.) You may not be able to see into a black hole, but they are sort of tough to ignore.
Obviously you are using the word "inconsistent" in a different way than it is used in Mathematics or even in Physics. General Relativity is, basically, Semi-Riemannian Geometry with a given interpretation of some of its mathematical concepts. So it is mathematically consistent ( assuming consistency of ZFC ).
No it is not consistent, and at a very fundamental level. We talk about the Schwarzschild radius of a black hole, while ignoring the fact that GR says it is infinite. Any radius beginning at the center of a black hole is infinite in GR. That rubber sheet gets stretched to infinity. It is possible to (approximately) measure the circumference at the event horizon and divide by 2π, but that radius is not physical. Similarly, if I measure the potential energy of two particles relative to a black hole and subtract, I get garbage. The distributive law doesn't work. To be blunt, anywhere in a GR universe with at least one black hole, I can prove that 2+2=5, or 42, or whatever. Do I believe that there is a version of GR that gets rid of the infinities? Sure. It may or may not be physically correct, it is hard to take measurements inside a black hole, but it could be consistent. Hawking has recently done some work which says that the event horizon may be impossible to measure accurately. So the best we can do for now is to say that we have a (mostly) consistent physics except near black holes.
Another different thing (and I think this is what you are trying to point out) is that it is more useful or less useful, depending on what you want to do with it.
No, what I said was: "That it is useless to try merging GR and QM." Right now, absent black holes, GR is consistent, and so is QM. But wishing black holes away doesn't work. And the really nasty piece of work in GR is that it is possible for things, particles, information, anything to violate causality and do it outside the event horizon (in the ergosphere). So the problems with GR are not localized to the region of black holes like we might hope, but can spread to anywhere within the event cone of the black hole.

I would like for someone to "fix" that part of GR, but it seems impossible. You may have heard the joke: "QM, GR, and causality. Pick any two." If you try to rigorously merge QM and GR, causality seems to go out the window. Way out the window. Maybe someone can come up with a logic that works without causality, but I am not holding my breath. Until then the best choice seems to be some version of GR where the distortion of space in the area of a rotating black eliminates time-travel. Hawking seemed to be headed this way with his closed timelike loops (CTL). A true CTL outside an event horizon would contain immeasurable energy. (See Heisenberg.) If every route around a black hole that violates causality has to cross a CTL then causality is preserved. (Unfortunately, this may be true for a static rotating black hole, but throw enough mass in and you may be able to sneak through.)

If you are trying to say that there will always exist things that we can not predict or calculate with "total" accuracy, or even that there will still exist things that we can not even "explain"...well, it is probably true.
It is true, it was proved a century ago by Godel. Douglas Hofstetter's book "Godel, Escher, Bach, an Eternal Golden Braid" is probably the best book on the subject for non-specialists. The writing is excellent, but the material is very hard. What you should get out of the book is that there are true statements that cannot be proven true in any consistent formal system. (You will also understand emergent properties very well.)

But what the heck does it have to do with us creating better and better models with larger range of validity?

I mean, it seems to me you were kind of criticizing our efforts of trying to create models of quantum gravity (or whatever we think will be the next improvement in our quest for consistent models with larger range of validity), basing your opinion in that there will always be things we, possibly, could not explain or predict.

It is that what you're trying to say?

The point that (current) GR and QM cannot be usefully merged is very worth knowing. (AKA the renormalization issues are impossible.) Loop quantum gravity (LQG) and spin foams may result in a version of gravity that is consistent even inside event horizons. Then a merger with QM becomes useful.

Finally, the press may like the name theory of everything (ToE) for a unified field theory(UFT). But the distance between a UFT and a ToE is not just immense. It may be impossible to cross. (A real ToE at least has to deal with dark matter and dark energy.)
 
  • #33
Well I certainly won't worry about the 'Press'
I have not even a theory off how all these apps I did not ask for start turning up on my new phone.
 
  • #34
eachus said:
When you accept even simple mathematics (2+2=4) , you get Godel's proof along with it. Most of the time you can kick it into a corner and ignore it. Other times, it is in your face. I remember a time when studying the strong force meant dealing with infinities. Fortunately renormalization came along and pushed those infinities back into the dusty corners. But with general relativity, there are still infinities, and they are in the black holes that are all over the place. (On a stellar scale at least.) You may not be able to see into a black hole, but they are sort of tough to ignore.

Again, you are confounding things. Mathematics and Physics are different things. I tried to explain it to you in previous posts.

No it is not consistent, and at a very fundamental level. We talk about the Schwarzschild radius of a black hole, while ignoring the fact that GR says it is infinite. Any radius beginning at the center of a black hole is infinite in GR. That rubber sheet gets stretched to infinity. It is possible to (approximately) measure the circumference at the event horizon and divide by 2π, but that radius is not physical. Similarly, if I measure the potential energy of two particles relative to a black hole and subtract, I get garbage. The distributive law doesn't work. To be blunt, anywhere in a GR universe with at least one black hole, I can prove that 2+2=5, or 42, or whatever. Do I believe that there is a version of GR that gets rid of the infinities? Sure. It may or may not be physically correct, it is hard to take measurements inside a black hole, but it could be consistent. Hawking has recently done some work which says that the event horizon may be impossible to measure accurately. So the best we can do for now is to say that we have a (mostly) consistent physics except near black holes.

No, what I said was: "That it is useless to try merging GR and QM." Right now, absent black holes, GR is consistent, and so is QM. But wishing black holes away doesn't work. And the really nasty piece of work in GR is that it is possible for things, particles, information, anything to violate causality and do it outside the event horizon (in the ergosphere). So the problems with GR are not localized to the region of black holes like we might hope, but can spread to anywhere within the event cone of the black hole.

I would like for someone to "fix" that part of GR, but it seems impossible. You may have heard the joke: "QM, GR, and causality. Pick any two." If you try to rigorously merge QM and GR, causality seems to go out the window. Way out the window. Maybe someone can come up with a logic that works without causality, but I am not holding my breath. Until then the best choice seems to be some version of GR where the distortion of space in the area of a rotating black eliminates time-travel. Hawking seemed to be headed this way with his closed timelike loops (CTL). A true CTL outside an event horizon would contain immeasurable energy. (See Heisenberg.) If every route around a black hole that violates causality has to cross a CTL then causality is preserved. (Unfortunately, this may be true for a static rotating black hole, but throw enough mass in and you may be able to sneak through.)It is true, it was proved a century ago by Godel. Douglas Hofstetter's book "Godel, Escher, Bach, an Eternal Golden Braid" is probably the best book on the subject for non-specialists. The writing is excellent, but the material is very hard. What you should get out of the book is that there are true statements that cannot be proven true in any consistent formal system. (You will also understand emergent properties very well.)

Again, you are confounding so many things. Some non-textbooks (or pop-science books) are entertaining, but almost always, only specialists understand what actually lies beneath.

"Godel, Escher, Bach, an Eternal Golden Braid" is a good non-rigorous book (I read it twice ten years ago, before studying Mathematics), but the things you think you understood about it, the way you state those things, clearly you didn't understand it (as I explained in previous posts).

Better start with this one: http://www.uv.es/ivorra/Libros/Logica.pdf (This is absolutely great, totally rigorous, but sadly it is in Spanish) or this other one: "Axiomatic Set Theory" (Suppes).

The point that (current) GR and QM cannot be usefully merged is very worth knowing. (AKA the renormalization issues are impossible.) Loop quantum gravity (LQG) and spin foams may result in a version of gravity that is consistent even inside event horizons. Then a merger with QM becomes useful.

Finally, the press may like the name theory of everything (ToE) for a unified field theory(UFT). But the distance between a UFT and a ToE is not just immense. It may be impossible to cross. (A real ToE at least has to deal with dark matter and dark energy.)

You mix things that has nothing to do with each other. You'll understand it all much better if you study Mathematics and Physics. Have to go back to work now, more later.
 
  • #35
Generally the "need" comes from the desire to answer the question: Is the universe created or did it just happen. If a UFT can be found, their is a reasonable next question: Why? Pretty much everyone wants to have a firm belief system. There are atheist that are sure of their position just like there are theists that are sure of their position. Then there is everyone else. They "need" to know if God exists or not. Atheists are sure he/she/it does not exist, but their belief is not more assured than the theist that says he/she/it does exist. Everyone else just wants to know. I think that "need" comes from trying to answer the 2nd question, "Why?"

The problem is this: the universe seems to be ordered. That flys in the face of atheists. (Which many if not most scientists claim to be.) But can order really come out of chaos (or nothing) by it's own accord? Science does it's best to prove it can, but for ever "hit" there is a corresponding "miss." So the point is that it's an unanswerable question. I personally believe Pi is the answer. Pi cannot be solved. It's a never ending quest but it's ultimately unknowable. For me, that proves God does exist because it proves the unknowable in an ordered universe. If the universe really created itself, then everything should be knowable. (Hence the "need" for a UFT.) The fact that there are unknowable elements in the universe seem to indicate that it's meant to be that way. It's a paradox by design.

Twice.
 
  • #36
matt621 said:
Generally the "need" comes from the desire to answer the question: Is the universe created or did it just happen.

What? Nothing to do with that (at least in my case and so many other scientist I work with).

If a UFT can be found, their is a reasonable next question: Why? Pretty much everyone wants to have a firm belief system. There are atheist that are sure of their position just like there are theists that are sure of their position. Then there is everyone else. They "need" to know if God exists or not.

What? What are you talking about?

What God do you mean?

We have created millions of totally different gods (and many other imaginary things) through the ages. Some of the concepts we create are useful, some others not that useful.

The creation of the concept of gods/deities by some humans may be an interesting thing (and some people like Ramachandran and others, try to explain it based on neuroscience knowledge), but as a useful concept to explain objective phenomena in a rational way...it has failed big time. Not useful at all.

Atheists are sure he/she/it does not exist, but their belief is not more assured than the theist that says he/she/it does exist. Everyone else just wants to know. I think that "need" comes from trying to answer the 2nd question, "Why?"

The problem is this: the universe seems to be ordered. That flys in the face of atheists.

What?

(Which many if not most scientists claim to be.) But can order really come out of chaos (or nothing) by it's own accord? Science does it's best to prove it can, but for ever "hit" there is a corresponding "miss." So the point is that it's an unanswerable question. I personally believe Pi is the answer.

My goodness, this is gold!

Pi cannot be solved. It's a never ending quest but it's ultimately unknowable.

We could even start a movie here...

For me, that proves God does exist because it proves the unknowable in an ordered universe. If the universe really created itself, then everything should be knowable. (Hence the "need" for a UFT.) The fact that there are unknowable elements in the universe seem to indicate that it's meant to be that way. It's a paradox by design.

Twice.

My goodness!

I don't know what to tell you man. I think it would help you a lot to study some things about Science and Philosophy, but I am not even sure about that anymore (many people I've met say they are better living without knowledge... :-) ).
 

Similar threads

  • · Replies 28 ·
Replies
28
Views
5K
Replies
20
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 2 ·
Replies
2
Views
9K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 13 ·
Replies
13
Views
4K
  • · Replies 6 ·
Replies
6
Views
4K