Can the Universe Cause Itself to Exist from a Physics Perspective?

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The discussion explores the concept of whether the universe can cause itself to exist from a physics perspective, with participants noting that this topic often veers into philosophical territory. Theories such as quantum fluctuations and the Big Bang are mentioned, suggesting that the universe may have emerged from a prior state, though the specifics remain speculative. The role of dark energy is highlighted, indicating that it complicates traditional models of the universe's fate, including possibilities like a Big Crunch or perpetual expansion. Participants express uncertainty about the origins of the universe and the nature of time before the Big Bang, emphasizing the need for further scientific exploration. Ultimately, the conversation reflects a blend of physics and philosophy, with no definitive answers currently available.
  • #31
DevilsAvocado said:
Thanks a lot Chalnoth! This kind of extremely interesting information makes me serious wonder if I did chose the wrong occupation...!? :eek:

You must keep this forum up to date, in case 'something' happens! :biggrin:

BIG THANKS!

Edit: And it for sure feels reassuring that this was not only a personal 'mad idea'... :smile:
Hehe.

Unfortunately, though, I strongly suspect that it will be quite a while before we have a solid quantum gravity theory.
 
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  • #32
Chalnoth said:
... Unfortunately, though, I strongly suspect that it will be quite a while before we have a solid quantum gravity theory.

Good things come to those who wait, and time is relative, Albert says... :wink:
 
  • #33
Chalnoth said:
... then maybe it will make perfect sense how a universe could randomly appear out of nothing.

Ops! It seems like we have a hard-nosed opponent to our beautiful quantum fluctuations in https://www.physicsforums.com/showthread.php?p=2545870#post2545870"... I see sparkles and I smell blood... :devil:


:smile:
 
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  • #34
celebrei said:
I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...

It is a speculation at least consistent with general relativity. A well known model of "self-creating" inflationary universe has been proposed by J. R. Gott and L-X. Li, "Can the Universe Create Itself?", Phys. Rev. D 58, (1998).
 
  • #35
There is a difference between multiverse creating sub-universes (via BH, or brane collisions etc) and "universe caused itself"
 
  • #36
xantox said:
It is a speculation at least consistent with general relativity. ...

Objection 1: GR will not take you all the way down to t0, it will break down at Planck time. So how can GR explain what caused the universe?

Can the Universe Create Itself?
Authors: J. Richard Gott, III, Li-Xin Li
(Submitted on 30 Dec 1997)

The question of first-cause has troubled philosophers and cosmologists alike. Now that it is apparent that our universe began in a Big Bang explosion, the question of what happened before the Big Bang arises. Inflation seems like a very promising answer, but as Borde and Vilenkin have shown, the inflationary state preceding the Big Bang must have had a beginning also. Ultimately, the difficult question seems to be how to make something out of nothing. This paper explores the idea that this is the wrong question --- that that is not how the Universe got here. Instead, we explore the idea of whether there is anything in the laws of physics that would prevent the Universe from creating itself. Because spacetimes can be curved and multiply connected, general relativity allows for the possibility of closed timelike curves (CTCs). Thus, tracing backwards in time through the original inflationary state we may eventually encounter a region of CTCs giving no first-cause.​

Objection 2: I’m a layman and may be wrong, but everything I've read so far says: First the extreme singularity at t0, then the 'Big Bang', and then Inflation...??

Objection 3: To me this seems like a very easy way out (almost silly) – not to explain how something came out of nothing, and instead try to prove that inside this universe there aren’t any laws preventing this phenomena!? Que? The physical laws of this universe apparently didn’t exist before the universe... AND the universe is here, isn’t it!? I mean – what will happen if they can prove that there is a law that makes the universe 'illegal'?? :biggrin:
 
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  • #37
DevilsAvocado said:
Objection 2: I’m a layman and may be wrong, but everything I've read so far says: First the extreme singularity at t0, then the 'Big Bang', and then Inflation...??
The singularity in the big bang theory is known to be wrong. By "before the big bang" they mean before the big bang theory was valid. The big bang theory is not valid at the earliest of times.

While inflation must have had a beginning, an actual singularity is a physical impossibility.

DevilsAvocado said:
Objection 3: To me this seems like a very easy way out (almost silly) – not to explain how something came out of nothing, and instead try to prove that inside this universe there aren’t any laws preventing this phenomena!? Que? The physical laws of this universe apparently didn’t exist before the universe... AND the universe is here, isn’t it!?
Basically, it appears to be the case that in the context of quantum mechanics, everything that is not expressly forbidden necessarily occurs. To supply a small analogy, consider quantum electrodynamics. In QED, we find that photons have the potential to exist everywhere in space-time. And merely because they have the potential to do so, they necessarily pop in and out of the vacuum all the time. Space-times might well follow a similar principle.

DevilsAvocado said:
I mean – what will happen if they can prove that there is a law that makes the universe 'illegal'?? :biggrin:
Then that law is a contradiction and must be false.
 
  • #38
Chalnoth said:
... And merely because they have the potential to do so, they necessarily pop in and out of the vacuum all the time. Space-times might well follow a similar principle.

Thanks for the explanation Chalnoth, I’m glad you’re out there.

I have been thinking a little bit more about (almost the same thing) what you said last time:

"then maybe it will make perfect sense how a universe could randomly appear out of nothing"​

We see virtual particles popping out (and in) of vacuum in the universe. This is a 'sign' of "how something can come out of nothing", right? And if this happens here, its not impossible it happened for the whole universe 13.8 billion years ago, right?

But, has anyone seen the 'laws of nature' popping out of nothing? Or any constants, like the 'weird' fine-structure constant (α = 0.08542455), or is this a completely unintelligent question...? That is... the laws and constants are 'embedded' in the particles, i.e. they 'know' what rules are present...

OMG... I don’t know what I’m talking about... 'laws' in vacuum... :redface:
 
  • #39
Laws don't appear or disappear, however. They simply are. Where this is concerned, I think that Tegmark's mathematical universe hypothesis is perhaps the most reasonable.
 
  • #40
Chalnoth said:
Laws don't appear or disappear, however. They simply are. Where this is concerned, I think that Tegmark's mathematical universe hypothesis is perhaps the most reasonable.

Okay, that means Dmitry67 (MUH) is right after all? :smile:
 
  • #41
DevilsAvocado said:
Okay, that means Dmitry67 (MUH) is right after all? :smile:
He hasn't said enough as to what he means with regards to the Mathematical Universe Hypothesis for me to offer a judgment either way.
 
  • #42
Chalnoth, about the Mathematical Universe Hypothesis, I must admit that I have very hard time to digest this way of looking at the physically reality... but it’s maybe a result of my 'status'...

To me, it’s pretty clear that humans don’t know everything, and (probably) never will. The 'thing' we call science is, and always will be, an approximation of what really goes on in nature. And mathematics is just a tool in this process, created by humans to make it graspable, not a 'divine thing' that created everything...

A classical example is QM. The mathematics works extremely well, and we build everyday functional machines on this knowledge. But is mathematics in QM really the hard blueprint of what really goes on at this level...?? It’s maybe stupid of me to speak in this matter - but my 'gut feeling' says no...

Tegmark's postulate is: All structures that exist mathematically also exist physically.
If we turn this around: All structures that exist physically exact also exist mathematically exact.

Is this true? I say no. Just look at ∏ ...

And what happens if String theory is proven wrong? What are all these new mathematical structures then, existing or non-existing physically?

What’s your opinion?
 
  • #43
Well, the thing is that we don't yet have any sort of theory of everything. In fact, we know that our current physical theories are necessarily just approximations to the true behavior (because they have various places where the mathematics become nonsensical).

The mathematical universe hypothesis isn't a hypothesis that we already know the mathematical structure that is our universe, but rather that there is one out there. Tegmark goes into a good argument for why this is reasonable, but in the end it boils down to simply this:

1. A mathematical structure is just a fully-consistent set of rules.
2. If our universe is fully consistent, then it is isomorphic to some mathematical structure (which we don't yet know). This would indicate that at least some mathematical structures have real existence.
3. It is generally easier for all things of a class to exist than for only some of them to, so it is simpler to propose that all mathematical structures exist.
 
  • #44
Chalnoth said:
He hasn't said enough as to what he means with regards to the Mathematical Universe Hypothesis for me to offer a judgment either way.

I just agree with Max Tegmark, so you can take his article

P.S.
Just read...
Your 1-2-3 is the shortest summary of Max article I've ever seen, very nice, cool!
 
  • #45
Chalnoth, I agree with Dmitry67, your 1-2-3 is very nice, and short enough to make sense even to me.

So, if a bright and young new 'Einstein' one day exclaims Eureka TOE! The guessing is over, and the speculation if mathematics is the real isomorphic mirror of reality, or just an approximation-tool of humans, has come to an end:

Mathematics is the physical reality, and the physical reality is mathematics.

:cool: Cool! :cool:


It’s also very exciting (for Tegmark) if the real nature of the physical reality turns out to be the QM-wayward-statistical-not-open-the-box-all-the-way structure... :devil:
 
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  • #46
Even if many scientists do now believe in the alternative universes, I think it is very important to study them for the better understanding of ours and for the A.P. below I put a list of the questions about the alternative universes. They are very deep and difficult, but at the same time it is NOT pure phylosophy, they are quite rigorous:

Take all parameters of the Standard Model, add density of DM, DE, gravitation. In this about 30-dimension space there is an 'island of observer-friendly universe'

1. How big is that island?
2. How close are we to the border of that island? are we at the center of not?
(more difficult)
3. Are there any other islands?

(now even more difficult, assuming, at least for some time, that MUH is true and all sorts of universes with different laws exist)
4. What are the requirements, in general, for an observer-friendly universe? (what mathematical systems are observer-friendly - note: that question can be studied by pure mathematics, but I think it require a theory of consciousness)
5. Is our universe the simplest observer-friendly universe or not?
6. Are there any better universes?
7. Can we somehow transfer our consciousness into such universes?
 
  • #47
For point number four, I think we'd just go for the most basic requirements today: you have to have stars that make heavier elements. This implicitly requires significant structure formation as well. I don't think we could do better than this simple requirement any time soon.
 
  • #48
Yes, but what's about universes without stars at all, so different from ours but still observer-friendly? Or universes with more then 1 time dimension?
 
  • #49
Dmitry67 said:
Yes, but what's about universes without stars at all, so different from ours but still observer-friendly? Or universes with more then 1 time dimension?
The reason why stars are important is that they are needed to produce the heavier elements that are required for complex chemistry.

And a universe with more than one time dimension has some nasty features that make such a thing highly unlikely, such as closed timelike loops.
 
  • #50
1. Yes, in OUR universe stars are important, I know. But imagine Universe where energy is not conserved. Observers there can develop on isolated blobs of matter, they won't need a central star. Now say heavier elements in their chemistry are developed during thir BB (like some part of our helium) - et voila, they don't need stars

2. unlikely? or difficult to imagine? :)
 
  • #51
Dmitry67 said:
1. Yes, in OUR universe stars are important, I know. But imagine Universe where energy is not conserved. Observers there can develop on isolated blobs of matter, they won't need a central star. Now say heavier elements in their chemistry are developed during thir BB (like some part of our helium) - et voila, they don't need stars
Albrecht and Iglesias looked at the implications of the fact that the time coordinate can be chosen arbitrarily on the laws of physics here:
http://arxiv.org/abs/0805.4452

They found that if you take a random Hamiltonian as input (which is the equivalent of taking the laws of physics as being random and changing in time), then you can simply make a change to the time coordinate to get a Hamiltonian that is constant in time. And if you have a Hamiltonian that is constant in time, then you have conservation of energy (by Noether's theorem).

Basically the upshot is that you can't have a universe where energy isn't, in some sense, conserved.

As for big bang nucleosynthesis, the problem there is that the production of carbon is so obscenely slow compared to the production of lighter elements that it effectively can't happen in the early universe.

Dmitry67 said:
2. unlikely? or difficult to imagine? :)
Like the BBN stuff, I'd have to look up the issues again, but I'm pretty sure that the existence of closed timelike curves leads to either contradictions or instabilities that make such a scenario impossible.
 
  • #52
Chalnoth said:
They found that if you take a random Hamiltonian as input (which is the equivalent of taking the laws of physics as being random and changing in time), then you can simply make a change to the time coordinate to get a Hamiltonian that is constant in time. And if you have a Hamiltonian that is constant in time, then you have conservation of energy (by Noether's theorem).

As for big bang nucleosynthesis, the problem there is that the production of carbon is so obscenely slow compared to the production of lighter elements that it effectively can't happen in the early universe.

At first, why Hamiltonian?
Alternative Universe can be so different so the laws are absolutely different.

Regarding the article, it is interesting. So there is time coordinate where Hamiltonian is constant, but why that coordinate IS time? (direction where entropy increases?)

Finally, regading the carbon production, what carbon? The laws can be so different that there are 2747 stable elements made of blahblarks Q, U, T, L, A and B :)
 
  • #53
Dmitry67 said:
At first, why Hamiltonian?
It's just one particularly way to write down arbitrary laws of physics.

Dmitry67 said:
Alternative Universe can be so different so the laws are absolutely different.
That was why they considered a random Hamiltonian.

Dmitry67 said:
Regarding the article, it is interesting. So there is time coordinate where Hamiltonian is constant, but why that coordinate IS time? (direction where entropy increases?)
I believe they chose the one where the Hamiltonian was constant.

Dmitry67 said:
Finally, regading the carbon production, what carbon? The laws can be so different that there are 2747 stable elements made of blahblarks Q, U, T, L, A and B :)
You might be surprised.
 
  • #54
Chalnoth said:
1 It's just one particularly way to write down arbitrary laws of physics.

2 I believe they chose the one where the Hamiltonian was constant.

2 then the direction of such time can be different from thermodynamic arrow.

1 hamiltonian can be used only in the narrow subset of all mathematical systems (=universes).
 
  • #55
Dmitry67 said:
1 hamiltonian can be used only in the narrow subset of all mathematical systems (=universes).
Why?
 
  • #56
Can you write a Hamiltonian for the Boolean Logic universe? (it is just an example)
Universe (in general) is not necesserily based on real/complex numbers.
 
  • #57
Dmitry67 said:
Can you write a Hamiltonian for the Boolean Logic universe? (it is just an example)
Universe (in general) is not necesserily based on real/complex numbers.
Since you can represent an arbitrary mathematical function in boolean logic, it would just be a matter of writing one down in computer code. Not that difficult.
 
  • #58
Chalnoth & Dmitry67, your latest talk about 'islands' and Hamiltonian is way above my 'horizon', but I have been thinking some more about the Mathematical Universe Hypothesis.

Dmitry67, when you mentioned "7. Can we somehow transfer our consciousness into such universes?", I started thinking about 'brains' and mathematics. If MUH is correct, our brain is 'just' a mathematical formula, right? Then we must have the 'mother lode' of formulas inside our heads, if we are going to explain 'ourselves', AND the universe, AND 'everything else', right?

Then I started thinking about something else, which is so 'simple', that Tegmark just couldn’t have missed it: Gödel's incompleteness theorems

I know this must be wrong, but I can’t find the error myself... :bugeye: (I also have to live up to my username hehe :devil:)
Second incompleteness theorem
For any formal effectively generated theory T including basic arithmetical truths and also certain truths about formal provability, T includes a statement of its own consistency if and only if T is inconsistent.

To me, this must mean we already know that your (Chalnoth) 1-2-3 boiling down of Tegmark’s arguments is inconsistent in the very first sentence:
Chalnoth said:
1. A mathematical structure is just a fully-consistent set of rules.
2. If our universe is fully consistent, then it is isomorphic to some mathematical structure (which we don't yet know). This would indicate that at least some mathematical structures have real existence.
3. It is generally easier for all things of a class to exist than for only some of them to, so it is simpler to propose that all mathematical structures exist.

If our universe is fully consistent and thus isomorphic to a mathematical structure, then TOE must be inconsistent to be able to prove the consistency of the universe!? Therefore the universe (=TOE) also must be inconsistent!? And if the universe is inconsistent, it cannot be a mathematical structure, therefore TOE can never be found (from 'inside')!?

Que? What am I missing... :confused:
 
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  • #59
Dmitry67 said:
What created (caused) number 7?

Numbers 6 and 8...

I would like to weigh in and say that the universe has been evolving since long before the BB. The BB is just one symptom of whatever started the whole process. This universe building process probably started in response to an overwhelming imbalance of nothing to something... as in a ratio of 0 to 1... 1 being "nothing" (in an abstract manner of course).
 
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  • #60
baywax said:
Numbers 6 and 8...

11 + 100 = 111

:wink:
 

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