big-bang fundamental problem

[north]

it is said that all matter and radiation was confined to a single point at that instant

 

this would imply a black-hole as the point

 

since nothing else could confine matter and more importantly radiation to a single point other than a BH

 

any thoughts

 

in otherwords ;

 

gravity cannot alone explain how radiation cannot eminate into space

 

and nor is common gravity strong enough to draw all matter towards a central point

 

it would take an un-common strength of gravity to create a BB

 

hence a black-hole ( BH )

[Martin]

it is said that all matter and radiation was confined to a single point at that instant...

 

I don't know any professional who says this. Do you have a reference to some recent scientific writing, that you can give a link to?

It would help to see exactly what was said, and whether the author was writing for other scientists, or just making popularization talk.

 

What you are saying doesn't sound right. If you want a better source, try Einstein-online website. I have a link to the Cosmology section of E-o in my signature. Check out the page called "A Tale of Two Big Bangs". It clears up some common misconceptions and confusions

[foodchain]

it is said that all matter and radiation was confined to a single point at that instant

 

this would imply a black-hole as the point

 

since nothing else could confine matter and more importantly radiation to a single point other than a BH

 

any thoughts

 

in otherwords ;

 

gravity cannot alone explain how radiation cannot eminate into space

 

and nor is common gravity strong enough to draw all matter towards a central point

 

it would take an un-common strength of gravity to create a BB

 

hence a black-hole ( BH )

 

I think you are thinking of a singularity, which I don't think exists with a neutron star right? Yet with the BH comes that singularity? I am just wondering if this is a BH or singularity thing.

 

Also, I am not sure but I think its based on the big bang itself, as modern physics has time or what not starting at the big bang. Does your question goes outside of that?

[Martin]

... as modern physics has time or what not starting at the big bang...

 

I don't think that is right. Can you back up your statement with some online source which speaks authoritatively for the modern physics community?

 

If you can't support what you are saying, then maybe you should do some reading.

 

Einstein-online would be a reasonable place to start. Link is in my sig. It is a public outreach website maintained by a prominent research institute. Here's a quote from that site's article called A Tale of Two Big Bangs

 

==quote Einstein-online==

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.

==endquote==

 

If you are interested I can back that up with links to a massive peer-reviewed published literature in non-singular cosmology, but i think the public outreach website from that institute may suffice for starters.

 

My point is you can't just speculate about what you think "modern physics says". It doesn't lead to any solid discussion. If you present some controversial opinion as fact then you have to come up with links that support what you claim.

Edited December 15, 2008 by Martin

[YT2095]

if it`s any help, that young fella with the odd haircut and almost constant grin that presents some of the recent LHC documentaries has said it a few times.

 

I forgot his name.

 

edit: Found it, he`s Dr Brian Cox.

[Martin]

People do say that kind of thing when they are talking to a wide audience.

I don't know of any scientist (specializing in cosmology anyway) who would say that in a professional context.

 

To take Brian Cox as an example. Here is a list of all his professional publications, written for other physicists, not for public.

 

http://arxiv.org/find/hep-ph/1/au:+Cox_B/0/1/0/all/0/1

 

I doubt you could find one instance in all 23 research papers where he says that the big bang was the beginning of time. Maybe north or foodchain would like to scan thru and see if they can find an explicit statement or even an implication.

 

Brian Cox is in any case an experimental particle physicist who has never written a research paper about the Big Bang or about anything in cosmology. He would not be much of an authority to cite either way. He is an attractive figure---used to be a rock musician I believe. I believe his appearances on Telly benefit science because they present an appealing enthusiastic image of the LHC, helping to consolidate support. But any references to the Big Bang he makes would best be taken with a grain of salt.

Edited December 16, 2008 by Martin

[YT2095]

I agree, and it was a documentary aimed towards the general public (I think we already have a thread about "Discovery channel" type documentaries as well).

to be honest those where the Only times I`v heard it used as a concept.

[foodchain]

I don't think that is right. Can you back up your statement with some online source which speaks authoritatively for the modern physics community?

 

If you can't support what you are saying, then maybe you should do some reading.

 

Einstein-online would be a reasonable place to start. Link is in my sig. It is a public outreach website maintained by a prominent research institute. Here's a quote from that site's article called A Tale of Two Big Bangs

 

==quote Einstein-online==

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.

==endquote==

 

If you are interested I can back that up with links to a massive peer-reviewed published literature in non-singular cosmology, but i think the public outreach website from that institute may suffice for starters.

 

My point is you can't just speculate about what you think "modern physics says". It doesn't lead to any solid discussion. If you present some controversial opinion as fact then you have to come up with links that support what you claim.

 

Thats very interesting. I was unaware of the professional side of things as I am only a student, and not of physics.

 

So with what you are saying, the universe might not have started with a big bang? That in professional physics that deals with this subject in particular, one could speculate about something other then the big bang and not be a complete crackpot?

[Martin]

So with what you are saying, the universe might not have started with a big bang?

 

The first question is what do you mean by the Big Bang?

You should read what it says at Einstein-online. Have you done this by any chance. It is very easy reading and will clear up many sources of confusion.

 

I would say that there is hardly any doubt that the Big Bang occurred about 13.7 billion years ago.

 

The interesting research is about events immediately preceding it.

What led up to it? What caused it?

 

I'd urge anyone who wants to learn about cosmology to try to get the word "singularity" out of their head. It has gotten a lot of people confused. There is no scientific evidence of a singularity. The evidence points to a moment of very high density and temperature (but not infinite density, and not necessarily localized at a small region.)

 

Some models, which are getting a lot of study currently, show that quantum effects reverse gravity at very high density, causing collapse to turn into a bounce, resulting in rapid expansion. those models essentially say that the Big Bang was a bounce.

 

These are non-singular cosmology models, because there is no singularity.

 

At this point I don't think anyone would claim to have a handle on "the beginning of time". The bounce, if it occurred, is a good MARKER, one can date events as one second before or one second after. It is where the singularity was imagined to be, if there really were one.

 

So it is a good Time Mark, but not reason to believe it is the beginning.

[Severian]

I do think that the OP makes a valid point. If you take the simple minded extrapolation of GR as a description of gravity and wind back the clock to the big bang, you will indeed find that you get energy densities large enough to create a black hole. So it is not a very consistent theory.

 

The crucial point in the above though is that this is a simple minded extrapolation. GR is a classical theory with no quantum mechanics in it. As things move towards a point (going backward in time) we will eventually have to take quantum mechanics (the physics governing things at very small distances) into account. Unfortunately, at this time we do not have a working theory of quantum gravity, so we cannot do this yet.

 

Having said that, this is not really what the big bang model is about. The quantum effects are only relevant for the first very very tiny time interval, and after that GR is a good enough approximation to gravity. The big bang model is really describing how things happened after this initial period of uncertainty, and it does a very good job.

 

Indeed, that is really all we can do. At this stage, any speculation as to what came before is just... speculation.

[north]

The first question is what do you mean by the Big Bang?

You should read what it says at Einstein-online. Have you done this by any chance. It is very easy reading and will clear up many sources of confusion.

 

I would say that there is hardly any doubt that the Big Bang occurred about 13.7 billion years ago.

 

based on gravity I assume

 

 

 

 

The interesting research is about events immediately preceding it.

What led up to it? What caused it?

 

I'd urge anyone who wants to learn about cosmology to try to get the word "singularity" out of their head. It has gotten a lot of people confused. There is no scientific evidence of a singularity.

 

The evidence points to a moment of very high density and temperature (but not infinite density, and not necessarily localized at a small region.)

 

but still based on the effects of gravity

 

Some models, which are getting a lot of study currently, show that quantum effects reverse gravity at very high density, causing collapse to turn into a bounce, resulting in rapid expansion. those models essentially say that the Big Bang was a bounce.

 

sounds reasonable since I look at the compression of matter much like hydrolics , you can only compress matter so far , until it either stops the compression or pushes back

 

 

 

These are non-singular cosmology models, because there is no singularity.

 

perhaps

 

but this depends on how you define " singularity "

 

At this point I don't think anyone would claim to have a handle on "the beginning of time". The bounce, if it occurred, is a good MARKER, one can date events as one second before or one second after. It is where the singularity was imagined to be, if there really were one.

 

So it is a good Time Mark, but not reason to believe it is the beginning.

 

the beginning of " time " is NOT the important question

 

the important question is the begining of the manifestation energy>matter

 

and the answer is infinity

 

the infinity of the existence of energy>matter

Edited December 17, 2008 by north

[snp.gupta]

...

 

I'd urge anyone who wants to learn about cosmology to try to get the word "singularity" out of their head. It has gotten a lot of people confused. There is no scientific evidence of a singularity. The evidence points to a moment of very high density and temperature (but not infinite density, and not necessarily localized at a small region.)

 

Some models, which are getting a lot of study currently, show that quantum effects reverse gravity at very high density, causing collapse to turn into a bounce, resulting in rapid expansion. those models essentially say that the Big Bang was a bounce.

 

These are non-singular cosmology models, because there is no singularity.

 

....

 

Sir,

 

what is your openion, Bigbang is "singularity" or not?

[Baby Astronaut]

Sir,

 

what is your openion, Bigbang is "singularity" or not?

I can't speak for Martin of course, but it seems clear that Martin has said lots against the singularity, and nothing for it. Even within the part you quoted it's apparently treating the Big Bang singularity as misinformation or inconclusive.

[devrimci_kürt]

non-singular cosmology models

 

 

http://cbpfindex.cbpf.br/publication_pdfs/infaltion-nonsingular.2009_01_08_14_15_01.pdf

[SH3RL0CK]

it is said that all matter and radiation was confined to a single point at that instant

 

this would imply a black-hole as the point

 

since nothing else could confine matter and more importantly radiation to a single point other than a BH

 

How do you know there is no other singularity possible than a black hole? You assume it was a black hole because it is the closest thing we know to what would have been the big bang precursor. But this does not mean the precursor could have been some other type singularity. Given that a black hole evaporates via Hawking radiation, I submit a black hole is quite different than any BB precursor would have been.

Edited January 13, 2009 by swansont
fix quote tag

[Martin]

I do think that the OP makes a valid point. If you take the simple minded extrapolation of GR as a description of gravity and wind back the clock to the big bang, you will indeed find that you get energy densities large enough to create a black hole...

 

Actually he doesn't make a valid point, Sev. If you wind the usual (GR-based Friedmann) model back you do indeed get very high densities which would be sufficient to cause collapse to hole in a non-expanding spacetime.

 

However the model is not inconsistent as you say, because when you wind it back you do not get those high densities in a non-expanding situation. What you get is high densities in the context of rapid expansion, far too rapid even be much slowed by the gravitational effect of high density. I am not considering any assistance from inflation here, just the classical (circa 1923) Friedmann model, or GR itself. No inflaton field is needed to avoid collapse.

[swansont]

it is said that all matter and radiation was confined to a single point at that instant

 

it is said is a rather nebulous attribution, and you've been asked to give a more specific reference for the assertion. It is implied that this is standard cosmology/cosmogeny.

 

You need to support this claim.