How Can We Analyze the Singularity at the Big Bang?

[PhysDrew]

Hi,
I was just pondering the moment of the Big Bang, and have been doing some reading on the subject, in which there exists problems consolidating the mathematics of relativity and quantum mechanics. To my understanding the theory of realtivity predicts the universe started from the Big Bang, but in order to analyse it, the mathematics of quantum mechanics is required as well. This is due to the fact that the singularity at the event of the Big Bang is in the quantum realm. However to my understanding the notions of space and time were born from the big bang as well, including any notion of length or measurement. How can there be some sot of external 'measuring stick' that we can apply to the singularity so that we know we need to use Quantum mechanics? How is the Quantum realm determined? To what measurement does the 100 nm distance relate to? Diameter of the entity being analysed? Or the action of forces at that distance?
Anyway just some questions that I've been thinking about. Apologies for any ignorance displayed as I have only a limited understanding of these processes at the moment!
Thanks for your time

 

[marcus]

Drew, I have a link in my sig (at the end of the post) to a one-page essay that may help.
It is at the public outreach website of a major German reasearch institution--Max Planck Institute. They have a branch called AEI that specializes in cosmology and also unifying QG and GR.

Try the essay there called "A Tale of Two Big Bangs"

The MPI outreach website is called "Einstein Online"
http://www.einstein-online.info/spotlights/cosmology/?set_language=en

You might like some of the other stuff there as well.
The direct link to the "Two Big Bangs" essay is
http://www.einstein-online.info/spotlights/big_bangs

This is the only popularization website I know that points out the inconsistency in how scientists use the cosmological "singularity" idea, and how it causes members of the public confusion.

It's a short simply worded essay but makes some very important points. I hope it sheds some light on the subject for you! It may also parallel some of your own thinking which you described in the first post.

 

[marcus]

If anybody is reading and wants a thumbnail of that Einstein-Online outreach essay. They distinguish between the early expansion phase sometimes called "Big Bang" which may include inflation, the synthesis of elements, and extreme conditions, and, on the other hand the mathematical breakdown point where the classic model fails: the "singularity". It is not generally assumed that this existed in nature, or occurred. It is simply the failure of the model. But it is also called "Big Bang" because one can use it as a time-marker, to set up the timeline.

So they distinguish between the two and then continue as follows:

==quote==

Which is which?

Did the big bang really happen? If you are talking about the big bang phase, the hot early universe as described by well-known physical theories (or, if you include inflation, by extrapolation from those theories), then there is good evidence that, yes, nearly 14 billion years ago, the cosmos developed in just the way described by the cosmological models (the main exhibits are the original abundances of light elements as deduced from astronomical observation, the distribution of far-away galaxies and the existence and properties of the so-called cosmic background radiation).

Whether or not there really was a big bang singularity is a totally different question. Most cosmologists would be very surprised if it turned out that our universe really did have an infinitely dense, infinitely hot, infinitely curved beginning. Commonly, the fact that a model predicts infinite values for some physical quantity indicates that the model is too simple and fails to include some crucial aspect of the real world. In fact, we already know what the usual cosmological models fail to include: At ultra-high densities, with the whole of the observable universe squeezed into a volume much smaller than that of an atom, we would expect quantum effects to become crucially important. But the cosmological standard models do not include full quantum versions of space, time and geometry - they are not based on a quantum theory of gravity. However, at the present time we do not yet have a reliable theory of quantum gravity. While there are promising candidates for such a theory, none are developed far enough to yield reliable predictions for the very early universe...
==endquote==

 

[PhysDrew]

Hi Marcus,
Thanks for the link! I think I may have posted prematurely without doing more research into it myself! But it's good to know a great deal of others are uneasy about the singularity (theory). Guess I was duped by reading too many popular science books!
Thanks again.
Drew

 

[Radrook]

If we had an infinitely powerful microscope-could we see the infinitely small?

 

[skydivephil]

If anybody is reading and wants a thumbnail of that Einstein-Online outreach essay. They distinguish between the early expansion phase sometimes called "Big Bang" which may include inflation, the synthesis of elements, and extreme conditions, and, on the other hand the mathematical breakdown point where the classic model fails: the "singularity". It is not generally assumed that this existed in nature, or occurred. It is simply the failure of the model. But it is also called "Big Bang" because one can use it as a time-marker, to set up the timeline.

So they distinguish between the two and then continue as follows:

==quote==

Which is which?

Did the big bang really happen? If you are talking about the big bang phase, the hot early universe as described by well-known physical theories (or, if you include inflation, by extrapolation from those theories), then there is good evidence that, yes, nearly 14 billion years ago, the cosmos developed in just the way described by the cosmological models (the main exhibits are the original abundances of light elements as deduced from astronomical observation, the distribution of far-away galaxies and the existence and properties of the so-called cosmic background radiation).

Whether or not there really was a big bang singularity is a totally different question. Most cosmologists would be very surprised if it turned out that our universe really did have an infinitely dense, infinitely hot, infinitely curved beginning. Commonly, the fact that a model predicts infinite values for some physical quantity indicates that the model is too simple and fails to include some crucial aspect of the real world. In fact, we already know what the usual cosmological models fail to include: At ultra-high densities, with the whole of the observable universe squeezed into a volume much smaller than that of an atom, we would expect quantum effects to become crucially important. But the cosmological standard models do not include full quantum versions of space, time and geometry - they are not based on a quantum theory of gravity. However, at the present time we do not yet have a reliable theory of quantum gravity. While there are promising candidates for such a theory, none are developed far enough to yield reliable predictions for the very early universe...
==endquote==

Marcus, I am wondering if you think the phrase "none are developed far enough to yield reliable predictions for the very early universe..." is still appropriate in the light of this paper?
http://arxiv.org/abs/1011.1811

 

[Skolon]

If we had an infinitely powerful microscope-could we see the infinitely small?

What means "to see" for you?
At very small scale the "see" concept is extremely different from common seeing.