A universe from nothing

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haushofer
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Hi guys,

I was thinking about something, due to Hawking's new book "The grand design". I didn't read it completely, but the book argues that it is perfectly consistent that a universe is made "out of nothing",

Because there is a law such as gravity, the Universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the Universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the Universe going.
Every now and then I come accross the Hammoch physicist, which states about this:

What's this fuzz all about?

It all boils down to a media frenzy around a quotation declaring God unnecessary for starting up the universe:

"Because there is a law such as gravity, the universe can and will create itself from nothing. Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist [..] It is not necessary to invoke God to light the blue touch paper and set the universe going."

But again: why this hype? We know already for ages that the formation of our universe out of nothing is a perfectly viable and consistent hypothesis. In fact, given the constraints of the various cosmological observations, I know of no other workable alternative hypothesis.
I am surprised about this last "We know already for ages that the formation of our universe out of nothing is a perfectly viable and consistent hypothesis." Why is this consistent? How can it be consistent that a universe forms out of a state ("nothing", whatever that may be) of which we don't have a single clue what the laws of physics are? And how wide-spread is this idea among cosmologists and high-energy physicists in general?

It is argued, also by Hawking, that the universe perhaps has "zero energy"; the negative gravitational energy cancels the other forms of energy. But doesn't GR say that energy is absolute, contrary to classical physics and quantum field theories?

I'm curious about your thoughts about this! :)
 

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  • #2
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Hi guys,

I was thinking about something, due to Hawking's new book "The grand design". I didn't read it completely, but the book argues that it is perfectly consistent that a universe is made "out of nothing",
Hawking and religion do not speak about the same type of creation and Hawking really misunderstood the issue here or at least pretended to do so. What Hawking means with creation is creation in the sense as we understand it within the context of quantum field theory. You have creation and annihilation operators on some Hilbert space, a non-free Hamiltonian and a vacuum state. So, the vacuum state may evolve into a state with particles. This is precisely what third quantization of gravity is about: you get creation operators of (topologically nontrivial) universes and you allow them to scatter and so on and so forth. So the vacuum state is not really nothing as we know for ages. Religion on the other hand speaks about genuine creation, the formation of something which had no prescription in a symbolic language at all. That is, it's information was not even given to the Hilbert space of the universe itself. So, Hawking initiated a debate there never really was since he was talking about something far more mundaine.

I am surprised about this last "We know already for ages that the formation of our universe out of nothing is a perfectly viable and consistent hypothesis." Why is this consistent? How can it be consistent that a universe forms out of a state ("nothing", whatever that may be) of which we don't have a single clue what the laws of physics are? And how wide-spread is this idea among cosmologists and high-energy physicists in general?
See above concerning the two different notions of creation.

It is argued, also by Hawking, that the universe perhaps has "zero energy"; the negative gravitational energy cancels the other forms of energy. But doesn't GR say that energy is absolute, contrary to classical physics and quantum field theories?

I'm curious about your thoughts about this! :)
Well again, Hawking thinks too simple here. What does zero energy mean? For example, could we set up an experiment that measures the exact energy content of the universe? Can all energy be used for experiment?

Careful
 
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haushofer
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Hawking and religion do not speak about the same type of creation and Hawking really misunderstood the issue here or at least pretended to do so. What Hawking means with creation is creation in the sense as we understand it within the context of quantum field theory. You have creation and annihilation operators on some Hilbert space, a non-free Hamiltonian and a vacuum state. So, the vacuum state may evolve into a state with particles. This is precisely what third quantization of gravity is about: you get creation operators of (topologically nontrivial) universes and you allow them to scatter and so on and so forth. So the vacuum state is not really nothing as we know for ages. Religion on the other hand speaks about genuine creation, the formation of something which had no prescription in a symbolic language at all. That is, it's information was not even given to the Hilbert space of the universe itself. So, Hawking initiated a debate there never really was since he was talking about something far more mundaine.
So you say Hawking's idea presupposes a vacuum state, instead of "nothing"; or, to put it in different words, it heavily depends on what that "nothing" exactly is.

I don't see what one can explain more from this than the initial singularity in conventional cosmology.
 
  • #4
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So you say Hawking's idea presupposes a vacuum state, instead of "nothing"; or, to put it in different words, it heavily depends on what that "nothing" exactly is.
Obviously, these are the intrinsic limitations of physics.
I don't see what one can explain more from this than the initial singularity in conventional cosmology.
Ah, singularities like the big bang are a bit troublesome for the intial value point of view of general relativity you see and people somehow believe that since quantum mechanics smears out everything, likewise it should be so with the intial singularity so that our naive view of a linearly evolving universe can survive. There are several possible answers to this issue even within classical relativity by dismissing the idea that the universe should be complete or one could cook up alternative gravity theories with torsion where the singularity theorems do not really hold anymore, such as Einstein Cartan theory. What Hawking does is using a whole bunch of ''exotic physics'' which is extremely unlikely (we basically have never seen scattering of our universe with another) because he has psychological problems with the fact that a naked singularity appears to cruch the linear time picture of quantum mechanics in the Heisenberg and/or Schroedinger formalism too.

Careful
 
  • #5
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I haven't read "The Grand Design", but I assume he's referring to the no boundary proposal. From Hartle and Hawking "Wave Function of the Universe" Phys Rev D vol 28 No 12 15Dec 1983:

One can interpret the functional integral over all compact four-geometries bounded by a given three-geometry as giving the amplitude for that three-geometry to arise from a zero three-geometry, (i.e. a single point). In other words, the ground state is the amplitude for the Universe to appear from nothing.
 
  • #6
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I haven't read "The Grand Design", but I assume he's referring to the no boundary proposal. From Hartle and Hawking "Wave Function of the Universe" Phys Rev D vol 28 No 12 15Dec 1983:
Haha, Prigogine had something funny to say about Hartle Hawking: it came down to this. Hawking assumes that the universe started out in a euclidean phase and that time did not exist. Then, due to a quantum fluctuation, time arose spontaneously and the universe evolved. The strange thing is that this fluctuation already lasts for 15 billion years :biggrin: :biggrin:
 
  • #7
bapowell
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The quotation from the OP's post is completely false:

"In fact, given the constraints of the various cosmological observations, I know of no other workable alternative hypothesis."

There is no observational evidence that directs cosmologists to favor one origin of the universe theory over any other. Currently, science has no epistemological traction on questions regarding the big bang or other origin theories. Maybe one day, but for now we must be happy to content ourselves with understanding the universe from fractions of a second after the Planck density.
 
  • #8
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Haha, Prigogine had something funny to say about Hartle Hawking: it came down to this. Hawking assumes that the universe started out in a euclidean phase and that time did not exist. Then, due to a quantum fluctuation, time arose spontaneously and the universe evolved. The strange thing is that this fluctuation already lasts for 15 billion years :biggrin: :biggrin:
To a cynic, it looked like the motiviation for the Euclidean phase was "because we can do the path integrals more easily there".

Anyway, I'm pretty sure that's what he must have been alluding to by "universe from nothing" in the Grand Design, given that almost the same phrasing is used in Hartle and Hawking. I've seen other objections to it based around the interpretation of probabilities and normalisation.....

Edit - or maybe not - I just saw bapowell's post - maybe the quotation was inaccurate ? I really must get new glasses - the "universe from nothing" was the phrase used by the "Hammock physicist", not Hawking
 
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  • #9
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Post #7 is right on:

The quotation from the OP's post is completely false:

"In fact, given the constraints of the various cosmological observations, I know of no other workable alternative hypothesis."
In addition this "something from nothing" has not been "known for ages". In fact it's quite new: I'd suggest it was not until the Einstein's work was expanded in the 1920's and 1930's supplemented by the concept of inflation in the 1960's that a big bang theory gained real traction...that is widespread acceptance.

Satellite Observations may be able to distinguish between a big bang scenario and the cyclic universe scenario ( ENDLESS UNIVERSE of Steinhardt and Turok) but not so far. Both theories so far fall within the realm of observational evidence. A particular type of subtle gravitational wave, if detected, may distinguish which model is correct.

Also, there is a big difference between "nothing" and (even a perfect) vacuum. The vacuum which many think of as "empty space" in fact includes space (distance, an entity) as well as vacuum fluctuations even if that geography is isolated from the rest of the universe. We so far believe that at another type of singularity, that of a black hole, space and time and matter cease to exist and yet mass remains. So it appears they may be combinations of things we know and things we don't in combinations we know and combinations we don't: dark matter and dark energy, for example. What's up with them??
 
  • #10
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To a cynic, it looked like the motiviation for the Euclidean phase was "because we can do the path integrals more easily there".

Anyway, I'm pretty sure that's what he must have been alluding to by "universe from nothing" in the Grand Design, given that almost the same phrasing is used in Hartle and Hawking. I've seen other objections to it based around the interpretation of probabilities and normalisation.....
Perhaps, but he shouldn't have done the merchandising as if he had solved long standing tensions between religion and science. As far as I see, there are no real tensions between both. On the technical side, the HH wavefunction is just a special state in the context of third quantization... ah well :wink:
 
  • #11
PhilKravitz
he shouldn't have done the merchandising as if he had solved long standing tensions between religion and science
It is merchandising. It is hype. The purpose is to sell books and make money. To provide for his family. Good on him.
 
  • #12
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It is merchandising. It is hype. The purpose is to sell books and make money. To provide for his family. Good on him.
Strange, I always thought the purpose was to do good work :bugeye: BTW: nobody buys books in these days anymore, you can get all decent books for free from Russian pirat sites, just download Djvu and you are settled for life.
 
  • #13
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One point of view is that 'nothing' is invariant under every conceivable symmetry, and hence, a lot of physical laws apply to it -- in particular, time translation symmetry implies energy conservation, gauge symmetry implies quantum mechanics (as argued by Victor Stenger), and supersymmetry holds; so if we want to create a universe ex nihilo, we need something like gravity to balance the books, and since we have QM, we can nucleate a universe Vilenkin-style. From Hawking's point of view, supersymmetry is then needed to get everything to give out finite answers, with the most general supersymmetric theory of quantum gravity being M-theory.

To me, this isn't a convincing argument; but it also isn't as simplistic as it has been widely caricatured.
 
  • #14
qsa
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One point of view is that 'nothing' is invariant under every conceivable symmetry, and hence, a lot of physical laws apply to it -- in particular, time translation symmetry implies energy conservation, gauge symmetry implies quantum mechanics (as argued by Victor Stenger), and supersymmetry holds; so if we want to create a universe ex nihilo, we need something like gravity to balance the books, and since we have QM, we can nucleate a universe Vilenkin-style. From Hawking's point of view, supersymmetry is then needed to get everything to give out finite answers, with the most general supersymmetric theory of quantum gravity being M-theory.

To me, this isn't a convincing argument; but it also isn't as simplistic as it has been widely caricatured.
Assuming the MUH ala DR. Tegmark, you can have a universe starting with zillion numbers in a certain configuration and evolving with certain rules. Now imagine a universe with empty set and then numbers are added with some algorithm for evolving them. So, it is very easy to imagine a universe that started out as nothing.
 
  • #15
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"Something from nothing"??? How can nothing result in, produce, or materially imply the necessity of something? Well, we have in deductive logic the relationship between statements that is called "material implication", where one statement, called the premise, implies another statement called the conclusion. Implication holds between any two statements as long as the truth of the premise does not imply the falsity of the conclusion. Implication allows all other truth values between premise and conclusion, including a false premise and a true conclusion. It is legitimate to have a false premise imply a true conclusion.

Since we describe every physical situation, phenomena, event, thing, or entity with a propositions, we represent things that "exist" with propositions that are "true". Then logic and all its relationships between statements becomes relevant to the discussion. Certainly, we expect all the facts in reality to be consistent with and imply each other. What we cannot accept is one existing fact to prove the non-existence of another existing fact. So if logic holds even at the beginning, it is legitimate for something to come from nothing.
 
  • #16
tom.stoer
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It is argued, also by Hawking, that the universe perhaps has "zero energy"; the negative gravitational energy cancels the other forms of energy. But doesn't GR say that energy is absolute, contrary to classical physics and quantum field theories?
I don't like Hawking's writing very much. In general situations (expanding universes, ...) energy cannot even be defined uniquely in GR. Of course energy density (or better: the energy-momentum tensor) is well-defined and is conserved locally; but the global concept of "energy within a region" is still a matter of debate. But As soon as energy is no longer well-defined, the idea of "cancellation of gravitational and normal energy" becomes even more foggy. In addition there are extensions of Einstein's GR (Einstein-Cartan-theory - which seems to be a much more natural framework for gravity and perhaps quantum gravity) where even local conservation laws are modified!

Of course Hawking knows all this - but he misses to explain to his readership that there are fundamental conceptual problems. That's why I think his popular books are not always a helpful for physics and physicists.
 
  • #17
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Of course Hawking knows all this - but he misses to explain to his readership that there are fundamental conceptual problems. That's why I think his popular books are not always a helpful for physics and physicists.
True, Penrose does a much better job in presenting the material more in depth, even if one might disagree with him on several issues. Moreover, Penrose is a better mathematician than Hawking is; Hawking's best research has been in the 1970 ties when he worked together with Penrose, Ellis and others with superior mathematical skills (which is something very different than good calculational skills).

Careful
 
  • #18
haushofer
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I'll certainly read this Hartle and Hawking paper, thanks for the link! I understand that things are a whole lot more subtle than the popular literature seems to imply :)
 
  • #19
MathematicalPhysicist
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To argue that something strated from nothing is logical contradictory, because you need something to get it started and from nothing you don't have anything.

But there's a distinction in philosophy of science between people who are called actuallists who assert that the things are the way they are because that's their nature, and potentialists who assert that this thing is defined with regards to something else which has different notion.
Aristotle is considered actuallist and Newton is considered potentialist.

But saying something got started from nothing is perplexing and don't tell us a lot.
 
  • #20
tom.stoer
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Of course one has to define "nothing".

I think there is a rather clear picture what "nothing" means in a QFT, it is just the vacuum |0>. If you can formulate a quantum gravity theory in a way such that it has a vacuum state |0> with zero volume and if this vacuum state can "tunnel" into something else which behaves similar to our universe i.e. has "expanding volume" where expansion is formulated according to some "clock time", then you have a creation out of nothing.
 
  • #21
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Of course one has to define "nothing".

I think there is a rather clear picture what "nothing" means in a QFT, it is just the vacuum |0>. If you can formulate a quantum gravity theory in a way such that it has a vacuum state |0> with zero volume and if this vacuum state can "tunnel" into something else which behaves similar to our universe i.e. has "expanding volume" where expansion is formulated according to some "clock time", then you have a creation out of nothing.
There is a lot of mathematical structure involved with even specifying |0> of QFT. This math structure came about by describing something physical. I'm not sure it applies to "nothing". It seems you'd have to be able to justify the QFT formalism based on first principles of reasoning alone before you could apply it in the process of bringing something from nothing. Our curve fitting or symmetry fitting math to fit the experimental data does not apply to the physical state of "nothing". So it seems you need to justify the math you would use before applying it to prove that something can come from nothing. So I think something from nothing is the same as physics derived from pure logic, and not from any particular physical fact or initial conditions.
 
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  • #22
PhilKravitz
But saying something got started from nothing is perplexing and don't tell us a lot.
Yes. Indeed.

They would have to explain how and why for it to tell us anything useful.

Just saying first nothing then universe is not experimental data it is just an assertion.
 
  • #23
qsa
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There is a lot of mathematical structure involved with even specifying |0> of QFT. This math structure came about by describing something physical. I'm not sure it applies to "nothing". It seems you'd have to be able to justify the QFT formalism based on first principles of reasoning alone before you could apply it in the process of bringing something from nothing. Our curve fitting or symmetry fitting math to fit the experimental data does not apply to the physical state of "nothing". So it seems you need to justify the math you would use before applying it to prove that something can come from nothing. So I think something from nothing is the same as physics derived from pure logic, and not from any particular physical fact or initial conditions.
a related question and probably more important question is what is reality made of. if you can answer that then the OP question will be much easier.Now, when we model reality and match it to experiment, ultimately the description is going to be mathematical which should en campus all experiments made and potential ones. so, is experiment a judge of our models or our models judge that the experiments we make are sufficient to comprehend reality.So, my tentative conclusion is that we can only describe reality in terms of numbers, I don't see a way around it. And that maybe the best really, because it makes more sense than any other alternative, at least to my mind.
 
  • #24
tom.stoer
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There is a lot of mathematical structure involved with even specifying |0> of QFT.
It depends; for the physical vacuum yes, for the Fock vacuum it's rather trivial.

This math structure came about by describing something physical. I'm not sure it applies to "nothing".
Of course this is an assumption. But in LQG it can be made rather precise.

It seems you'd have to be able to justify the QFT formalism based on first principles of reasoning alone before you could apply it in the process of bringing something from nothing. Our curve fitting or symmetry fitting math to fit the experimental data does not apply to the physical state of "nothing".
What do you mean by "curve fitting"?

If you look at LQG there is a rather precise meaning of "nothing", namly a state of zero volume (which is not unique). The problem is that physical evolution of this state is not yet well understood.
 
  • #25
No random event can create highly specialized structures . I can't imagine that random events created our universe . If so , then our universe may be totally unstable and there shouldn't be any living cells at all . Also random events cannot create The highly complicated Structure-Function relationship in living beings .
 

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