Hartle-Hawking Model (How the Universe Can Appear From Nothing)

[TimBowe]

Jim Hartle and Stephen Hawking speculated that the universe quantum-fluctuated into existence from nothing.

The Universe then exists because of one unlikely fluctuation of the vacuum, in which the energy A£ created could be so huge because the time At was small enough not to violate Heisenberg's uncertainty relation.

The Hartle-Hawking idea describes the universe as a giant quantum fluctuation.

In order to visualize Hawking's model, recall that, according to conventional Big Bang theory, the expanding universe, if represented in a Minkowski-like four-dimensional space-time diagram, resembles an ice cream cone whose pointlike tip is the initial singularity. Hawking showed that the near region of this tip can be modified so that its time dimension gradually turns into a space dimension and that the tip becomes a hemisphere as one moves beyond the Planck time. At the bottom of the hemisphere, the four-dimensional space-time degenerates into a four-dimensional spatial manifold from which time gradually emerges without an abrupt coming into existence, so that here is no instantaneous beginning of time. Thus, one would have solved the problem of the initial boundary conditions of the Universe.

 

[TimBowe]

There is nothing outside it. More precisely, there is no outside. There is no creation, it has neither beginning nor end. If the universe has no beginning and no end, we can’t ask why it was created at a particular moment in time because time ceases to exist.

 

[arunma]

It's an interesting theory, and I think it has merit (I'd be interested to see how it can be tested). Still, I don't fully understand what we mean when we say that the universe is $t_0$ years old. If the universe has no beginning as you say, then what is the meaning of the reciprocal of the Hubble parameter (times whatever prefactors the model requires)?

 

[TimBowe]

Hawking and Hartle have proposed a method of combining quantum mechanics and general relativity.

Heisenberg's Uncertainty Principle allows the conservation of energy to be violated for short periods of time and that the shorter period of time involved the greater the violation (in energy terms) can be. There is, therefore, a short, but finite, time interval after the singularity in which the energy required to create the whole Universe is available.

 

[Chronos]

Its an interesting idea, and fundamentally untestable. It assumes an a priori condition - quantum phyics as a 'background' which appears inconsistent with the 'nothing' premise.

 

[TimBowe]

Yes, it may not really be created from "nothing".

In Hawking's scenario, the universe doesn't have to be created from nothing. It's just there. It is a geometry of space and time. When the geometry changes- that is, when imaginary time becomes real time the universe begins. The change from nothing to something is literally a change in geometry.

"I wouldn't describe it as a universe being created from nothing, instead the universe just exists as closed Euclidean geometry. It doesn't have time so it doesn't have a beginning or end. The time we experience is something we construct."

Stephen Hawking

 

[S.Vasojevic]

This graphics is from WMAP's site. They seem to be pretty sure about universe starting with quantum fluctuation. So, pre-existing 'background', or what?

 

[TimBowe]

Imaginary time is another direction of time, one that is at right angles to ordinary real time. We could get away from this one-dimensional, linelike behavior of time. Ordinary time would be a derived concept we invent for psychological reasons.

Stephen Hawking

 

[justwondering]

This sequence of posts is all very interesting and, once again, shows how little we actually KNOW. If one likes a mystery, this subject sure fits the bill! All of THIS perhaps being just a perturbation about zero is really wild. I don't think that we even have a chance of 'knowing', EVER. Is it a total waste to try, or just that WE can't help ourselves in trying?

 

[FlyTy]

More answers lead to more and more questions. Yay, epic science battle!

Its been theorized that the universe is like a giant rubber band stuck in a cosmic dance. Collapsing only to re-expand.

If only it was as simple as black holes lead to white holes that lead to the creation of parallel universe.

 

[TimBowe]

In the Hartle-Hawking model there is no beyond, no boundary, everything is perfectly self-contained. There proposal makes a number of predictions which are characteristic of our observed universe.

 

[edpell]

Still, I don't fully understand what we mean when we say that the universe is $t_0$ years old. If the universe has no beginning as you say, then what is the meaning of the reciprocal of the Hubble parameter (times whatever prefactors the model requires)?

I would say time like velocity is a measure between two points.

The time from the universe having an average temperature of 10 billion degree and having an average temperature of 2.7 degree is about 13 billion years. In order to say what did the universe look like 30 billion years before now there would have to be a time and a place 30 billion years distant. If that place does not exist then we can say there was no universe at 30 billion years ago.

 

[aib]

In the universe EVERYTHING happens for a reason, one of the things that I've found to be particularly inconsistent is the old claims back in the Sagan days, that there was nothing prior to the universe, and then "bang" - some event, caused by nothing. In the current model the universe is expanding, so it also must be expanding into some medium. Sorry well established mainstream science, but I don't see the current model working. It is either there was something prior to the universe and something outside of it - that would make the current *finite with a starting point* model work, if there is a larger than the universe scale structure we cannot observe, or it is the universe had no beginning, will have no end, and is truly infinite.

 

[TimBowe]

The universe can have no beginning, no end, and be finite and unbounded.

 

[justwondering]

In the universe EVERYTHING happens for a reason, one of the things that I've found to be particularly inconsistent is the old claims back in the Sagan days, that there was nothing prior to the universe, and then "bang" - some event, caused by nothing. In the current model the universe is expanding, so it also must be expanding into some medium. Sorry well established mainstream science, but I don't see the current model working. It is either there was something prior to the universe and something outside of it - that would make the current *finite with a starting point* model work, if there is a larger than the universe scale structure we cannot observe, or it is the universe had no beginning, will have no end, and is truly infinite.

"In the universe EVERYTHING happens for a reason"

True, and those 'reasons' may ALL be just pure chance! Perhaps it makes a neater picture/concept if there were nothing before the Big Bang. Nothing like a fresh start you know.

 

[BigFairy]

Thanks for the updates