Is the big bang singularity really a rapid expansion of spacetime?

[Apophenia]

The bulk of this would be to expand my understanding of what a field actually is so please keep that in mind.

I don't think the 'virtual particles from nothing' is a mainstream scientific theory but would like to discuss for the above reason. I have watched some videos of Lawrence Krauss discussing a 'Universe from Nothing' and have stumbled on some confusion.

1) At one point he states, "Nothing is not nothing anymore, it is a boiling, bubbling brew of virtual particles..."

Now, in order to remove this from a semantic debate I would like to define:
1) can be taken to mean he defines nothing as the '... bubbling virtual particles' or he means that nothing inevitably becomes ' ...bubbling virtual particles'. I am not sure what Krauss actually meant but I was discussing this with someone who said that he meant the latter; nothing means the absence of matter (particles) and his statement is referring to nothing eventually becoming virtual particles. For some explanation on this I was told that underlying fields can be found to give rise to these particles.

Now this is where the specificity of my question shifted from understanding what Krauss said (which if you understand it correctly can give some explanation) to what a field actually is.

My understanding of a field would be in the classical sense: a vector field of the velocity of fluid particles is a RESULT of the fluid particles. A gravitational field is the RESULT of the existence of particles with mass.

Correct me if I have some misinterpretation but I see the field as a description of the effects of matter; I see fields as a result of matter (or I suppose you can say elementary particles). A field cannot be said to exist without the presence of what creates it (I suppose it can also be said matter cannot exist without a field that determines it. It may be better not to look at it as a RESULT but as a mutual relationship.)


Either way, result or mutual relationship (one cannot be said to exist without the other):
Assuming that there is only nothing in a given area of space(no matter or particles what so ever) how can a field be said to exist to give rise to these virtual particles? I have no knowledge of quantum fields or quantum physics in general so perhaps there is a distinction between them and my conception of a 'classical field' that enables this. That's assuming the explanation I was told of Krauss's statements is correct to some extent... which I do not know.



Not immediately related but...

On wiki it states, "This utility leads to physicists believing that electromagnetic fields actually exist, making the field concept a supporting paradigm of the entire edifice of modern physics. That said, John Wheeler and Richard Feynman have entertained Newton's pre-field concept of action at a distance (although they put it on the back burner because of the ongoing utility of the field concept for research in general relativity and quantum electrodynamics)."

Out of curiosity: Does anyone have any further information on the Feynman and Wheeler remark (if it has merit)? ...or to what that is referring?


Thanks

 

[Dale]

You worry too much about nothing.

 

[Mordred]

This comes up often in the cosmology forum. Probably where this thread is best suited.
The virtual particle inflationary model Krauss is referring to started A.Guth false vacuum model. In that model what we describe as nothing cannot stay stable. The Heisenburg uncertainty principle takes effect. This leads to virtual particles popping in and out of existence. Now one key note in the model is that the total energy balance must equal zero with gravity being negative energy.

When inflation occurs their is an overall density. During inflation this density or pressure does not change instead energy is borrowed from gravity. The virtual particle interactions along with the Higgs field describe this process. False vacuum is the lowest energy state separated by a barrier between that and the true vacuum. As virtual particles tunnel through the barrier to the true vacuum they become real particled.
This model has led ti several later in models. Old inflation. New inflation, chatic eternal inflation. Bubble universes. Their are others.
The reason for the later models is that the inflationary model suffers one major problem that of runaway inflation. Once inflation starts it does not stop.
I would have ti refamiliarize myself with this model to answer what is the true vacuum and what comprises the barrier. However if uou google false vacuum cosmology. It will provide some links showing the model. If you see a cylinder with a piston
your on the right track as that piston is used as a training aid.

 

[Mordred]

Here is a decent link with what I described above.

http://ned.ipac.caltech.edu/level5/Guth/Guth3.html

 

[Apophenia]

You worry too much about nothing.

Haha. Correction though: I have interest in nothing... no worries.

Here is a decent link with what I described above.
http://ned.ipac.caltech.edu/level5/Guth/Guth3.html

Thanks for the source Mordred.

 

[Mordred]

No problem feel free to ask questions on it I am sure someone can help

 

[skydivephil]

IF I recall correctly from Krauss's book he describes different possbile deinfitions fo the word nothing and different models based on those different definitions. One model is based on the assumption that virtual particles turn into real particles due to inflation. But another is that space and time themselves tunnel into existence from a conjectured state where there is no space or time. In this sense, its hard to see how there are even any fields as surely they need space to live in.
One thing to remember is that the "universe from nothing" idea is just one idea on the table, there are many others.

 

[keepit]

"virtual"

could it be that the virtual particles/energy entering and exiting our universe are the result of things going on outside our universe?

 

[Drakkith]

could it be that the virtual particles/energy entering and exiting our universe are the result of things going on outside our universe?

According to known science, no. But there are an endless amount of possibilities. What's important is to come up with the simplest theories and models that make the most accurate predictions using the fewest assumptions.

 

[Mordred]

There are numerous models that describe our universe gaining energy from other sources. String theory with branes is one such. One other is bubble universes.
virtual particles however are a result of perturbations and need not come from outside our universe.

 

[Pyzyq]

I think u haveneglected some factors in the process in ur deccision makin. atoms are mostlt empty space idk if particles are to but atoms are. Particles are like piece sof their field thatare mobile an d usefull. So really the universe could have arison out of asingularity so dense containing all fields peices thatbroke loose are particles or waves.

 

[Mordred]

The singularity described by the big bang is described as a rapid expansion of spacetime. Not that of a singularity like a black hole.
This was once considered but doesn't fit the data well for a variety of reasons.
The most accurate model is hot big bang and LamdaCDM.
neither model describes before 10^-43 seconds. However how evenly distributed the CMB is found both in its Homogeous and isotropic measurements fits the rapid spacetime best. As opposed to a big bang type singularity.