Is the birth of the Universe a random event?

[Plebeian]

i.e something happening out of nothing or was there no birth at all and all that exists today existed since forever?

 

[Kevin_Axion]

No one has a definite answer but here is an awesome program on it:

What Happened Before the Big Bang? BBC Part 1:

What Happened Before the Big Bang? BBC Part 2: http://www.youtube.com/watch?v=IVwirDNFQnI&feature=related
What Happened Before the Big Bang? BBC Part 3: http://www.youtube.com/watch?v=c7vTQ3Z9fmY&feature=related
What Happened Before the Big Bang? BBC Part 4: http://www.youtube.com/watch?v=wH-GmZaJxLY&feature=related
What Happened Before the Big Bang? BBC Part 5: http://www.youtube.com/watch?v=cSCMEO0Z3M0&feature=related
What Happened Before the Big Bang? BBC Part 6: http://www.youtube.com/watch?v=SzgcSxBIMGM&feature=related

 

[Plebeian]

A random Universe scares me tbh. It could begin anytime and end anytime. The laws of physics could suddenly change and what we know would be of no use.

 

[hadsed]

That's not quite how it works. It can't just randomly explode back into nothingness (well, from our current understanding it won't do that, but you can't ever be 100% sure..). The laws of physics might be changing, but you most definitely will not notice them, and maybe we might not ever (if it's even happening).

 

[binbots]

I like the Biologist theory in that documentery. I thought that made sense before I even saw it.

 

[Chronos]

The bounce scenario is an attractive alternative. It avoids the obvious paradox of the singularity. It creates, however, new problems. I'm unsure these are solvable if physical laws 'morph' with each cycle. Trying to figure out how physics 'works' in this universe is already difficult enough.

 

[Driftwood1]

The bounce scenario is an attractive alternative. It avoids the obvious paradox of the singularity. It creates, however, new problems. I'm unsure these are solvable if physical laws 'morph' with each cycle. Trying to figure out how physics 'works' in this universe is already difficult enough.

Why do you assume that a perpetually bouncing universe model avoids the singulairty probems?

there are models that use the imaginary time concept to avoid the singulairty altogether (may have been Hawking and a co-author in the 1970's that first proposed the model)

 

[Chronos]

Bounce models are by nature intended to avoid the singularity.

 

[Driftwood1]

i.e something happening out of nothing or was there no birth at all and all that exists today existed since forever?

The question you pose is an old one - it has baffled humans for eons

In cosmology the answer depends on the cosmic model you superimpose on the availiable data and observations.

You can select from many! Models that don't even require a Universal starting point.

You can have multiple universes and exotic geometries.

You can even exclude time if you wish

Thats the beauty of cosmology - its more of abstract mathematical philosophy rather than a sceintific discipline - although data has been streaming in over the past century or so.

 

[TungstenTesla]

Forgive me for being naive, but could someone explain how bounce models avoid the singularity? I thought the singularity was more or less assumed at this point.

 

[Chronos]

eg, http://www.sciencedaily.com/releases/2006/05/060515232747.htm
http://arxiv.org/PS_cache/arxiv/pdf/1007/1007.2929v2.pdf
http://deepblue.lib.umich.edu/bitstream/2027.42/64218/1/jcap8_03_002.pdf

 

[Driftwood1]

Forgive me for being naive, but could someone explain how bounce models avoid the singularity? I thought the singularity was more or less assumed at this point.

A very good and valid observation.

Its a misconception that the typical bounce cosmic model avoids the singularity - it doesn't.

The bounce model avoids the question of what was before a single big bang event and whether a trigger is needed - ie God or quantum fluctuation etc.

Effectively the typical bounce model has repeating singularity events that each result in a big bang - this is hardly avoiding the singularity now is it

 

[Chronos]

Try reading the links I cited before leaping to conclusions.

 

[Driftwood1]

Try reading the links I cited before leaping to conclusions.

You can also entertain the validity of the question posed before bouncing around like a gravity-less top

 

[Chronos]

Agreed, reading is optional when you already have all the answers.

 

[marcus]

Forgive me for being naive, but could someone explain how bounce models avoid the singularity? I thought the singularity was more or less assumed at this point.

The root meaning of "singularity" in mathematical science context is a failure of a man-made theory---a place where the model breaks down, blows up, fails to give meaningful numbers.

Popular literature, stimulating public imagination, has given a different meaning to the word just in unprofessional context.

But there have been singularities at various times in several different branches of physics. No one takes this as a sign that NATURE has a glitch Historically, the singularity eventually is RESOLVED or cured by improving/replacing whatever theory had the trouble.

The cosmo singularity is specifically a trouble with the 1915 theory of General Rel. People are now in the process of fixing the trouble. This will make the singularity go away, since it is by definition a failure of the theory, not of nature.

However it is convenient to use the failurepoint of the classic GR theory as a time-marker to DATE stuff. Like "one second after the singularity" or "100,000 years after the singularity".
One doesn't assume that a singularity occurred in Nature, but it gives a good place to put the zero of the time-line. Everybody uses the classic model and knows where it fails.
It's like other conventional zeros. like 0 AD. A clear visible marker.

There's a German research institute that has a public outreach website called "Einstein-online" which does a good job giving realistic explanations, without the usual hype. I keep the link in my signature at the end of the post. They have an essay there called A Tale of Two Big Bangs.

That essay explains the two senses----working cosmologists use it as a conventional zero, but do not expect that time actually stops there, as you go back. Read the essay for more clarification.

If you want to get caught up on early-universe research check out the proposals for the B-Pol and CMB-Pol missions. These may or may not get funding depending on economic conditions. They would be the next step after the Planck mission (currently in orbit, taking data.) Here for instance is the B-pol website. It has a menu with brief sections explaining the science and the instruments.

http://www.b-pol.org/index.php

These space observatories would be sensitive to polarization in the ancient light of the CMB (cosmic microwave background). This is what the "Pol" in B-Pol means.

Probably the best introduction to leading edge observational cosmology of the early universe is to read the non-technical parts of a paper that just came out by
Julien Grain, Aurelien Barrau, Thomas Cailleteau, Jakub Mielczarek. Read the first few paragraphs at the beginning and the conclusion section at the end. Those parts are easy--no math. I'll get the link:

http://arxiv.org/abs/1011.1811
Observing the Big Bounce with Tensor Modes in the Cosmic Microwave Background: Phenomenology and Fundamental LQC Parameters
Julien Grain, A. Barrau, T. Cailleteau, J. Mielczarek
12 pages, 5 figures
(Submitted on 8 Nov 2010)
"Cosmological models where the standard Big Bang is replaced by a bounce have been studied for decades. The situation has however dramatically changed in the last years for two reasons. First, because new ways to probe the early Universe have emerged, in particular thanks to the Cosmic Microwave Background (CMB). Second, because some well grounded theories -- especially Loop Quantum Cosmology -- unambiguously predict a bounce, at least for homogeneous models. In this article, we investigate into the details the phenomenological parameters that could be constrained or measured by next-generation B-mode CMB experiments. We point out that an important observational window could be opened. We then show that those constraints can be converted into very meaningful limits on the fundamental Loop Quantum Cosmology (LQC) parameters. This establishes the early universe as an invaluable quantum gravity laboratory."

Chronos already gave some relevant links and is giving the correct information in this thread---I don't want to get further involved but just give some backup detail.

BTW I think this thread should better have been started in Cosmology forum. How the U got started is part of what cosmology studies. It really helps to keep the topics sorted more or less consistently. You'll find that out if you stick around long enough.

 

[John232]

According to the laws of thermodynamics the universe would have had to always existed. The first law would have to be disproven before anyone could say how energy and matter was created in the Big Bang. I don't think anyone is going to have any luck with that.

 

[Plebeian]

My understanding of the Random Universe is Effect -> Cause-> Effect and so on. Here the existence of time is valid because it has a starting point, first law of thermodynamics does not hold, laws of physics can keep changing.

On the other hand a Universe that existed since forever is a giant mind ****. It probably has a cause - effect relationship as Cause-> effect-> cause-> effect and so on or Cause1 -> effect1 -> cause 2-> effect 2-> ...Cause N-> Effect N-> Cause 1 (like a circular loop or something). Here the existence of time is not valid, the laws of thermodynamics hold and the laws of physics don't change.

 

[Driftwood1]

According to the laws of thermodynamics the universe would have had to always existed. The first law would have to be disproven before anyone could say how energy and matter was created in the Big Bang. I don't think anyone is going to have any luck with that.

Can you apply the 4 laws of thermodynamics to the initial big bang event? that is to a singularity?

 

[Chronos]

That could be a clue something is amiss.

 

[Driftwood1]

That could be a clue something is amiss.

If anything has emerged from the scientific method it is that almost everything is amiss

 

[John232]

Can you apply the 4 laws of thermodynamics to the initial big bang event? that is to a singularity?

Energy can't be created or destroyed, how could someone apply the laws of thermodynamics to the big bang if energy was created in the process? The first law would have to be shown to be violated in some way before anyone could apply a theory to the big bang that stated that energy was created in the process.

 

[Tanelorn]

A random Universe scares me tbh. It could begin anytime and end anytime. The laws of physics could suddenly change and what we know would be of no use.

God could end his physics experiment at any time :)

 

[PhysDrew]

Energy can't be created or destroyed, how could someone apply the laws of thermodynamics to the big bang if energy was created in the process? The first law would have to be shown to be violated in some way before anyone could apply a theory to the big bang that stated that energy was created in the process.

Hmmm but at the 'birth' of the universe, spacetime itself was born from the big bang event. Hence to have a creation event (in this instance the creation of energy) one would need time itself to be already present. If there was no time, there are no laws of physics, and in this instance, there can't be any creation event as the creation of something requires time (that is, at one time there was nothing, and at another time this something came into being). The first law applies to the universe we live in now (with time), not at the big bang.