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arvin

Big Bang

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google and wikipedia are your friends.

 

Forums are not good for general information more for answering specific questions or clearing up difficulties.

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according to this theory,the universe had its origin in an giant explosion about 18,000 million years ago.the matter flung from the explosion condensed into lumps called galaxies,which are still rushing outwards.as the universe grows old,the matter in it thins out.the expansion continues indefinately.

if want to know in detail then check out google. :)

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I thought the bb was just the original creation/expansion of space.

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according to this theory,the universe had its origin in an giant explosion about 18,000 million years ago.the matter flung from the explosion condensed into lumps called galaxies,which are still rushing outwards.as the universe grows old,the matter in it thins out.the expansion continues indefinately.

if want to know in detail then check out google. :)

 

It's not an explosion, and it's not "rushing outwards" from anywhere. The universe doesn't have a center. It's space itself that is expanding.

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Not an explosion, not 18,000 million years ago, not rushing outwards. Otherwise, right on!

 

it was explosion n 18,000 million years ago and rushing outwards!i have taken data from a latest science magseen!

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it was explosion n 18,000 million years ago and rushing outwards!i have taken data from a latest science magseen!

 

Popular science magazines are not always the best source.

 

It was not an explosion in the blowing stuff us sense, everything came into being.

 

It is not rushing outwards, there is no out, there is no in, but space is expanding.

 

As for age, there's continued updates to this. Seems to range from 10 to 20...

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it was explosion n 18,000 million years ago and rushing outwards!i have taken data from a latest science magseen!

 

I'm sorry, book worm, but the information is still incorrect.

 

1. BB occurred about 13.7 billion years ago.

2. It was not an explosion.

 

http://www.astronomycafe.net/qadir/acosmexp.html Questions about Big Bang

http://curious.astro.cornell.edu/cosmology.php#questions Better questions about BB

 

This next one is a truly exceptional article that clears up a lot of misconceptions about the BB:

 

7. Lineweaver CH and Davis TM Misconceptions about the Big Bang, Scientific American 36-45 March 2005.

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Book worm, there was a bit about this in another post. Here's the link...

the bottom of the fouth post.

 

Plus for information on Big Bang Martin gave a great link (or I thought it was quite good for peoplewho don't know too much about the bb)...

[url=]http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147

It's quite long, but all good stuff.

:)

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BB theory, or that which is accepted scientific theory (so said), simply states that everything (that means everything) from a singularity which included this everything (including space) unexplainable began to expand at very great speeds away from a place that is not explainable (no center) and continues to this day. its said what formed from stuff inside that thing and as the new found space cooled matter formed, from the the new found gravity. originally or in the late 1920's this was thought to be about 3-5 billion years ago, but as known or now visible, this figure is 14.2 billion years ago.

 

rarely mentioned is the fact that there are alternative theory, many of which out date BBT, that are still very much considered. steady state or the theory that tries to explain things from an eternal existence or a version of this the most common.

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There are serious problems with the steady state theory of the universe.

 

laid out above was a composite, of a few current BBT or at least as i read it. personally i see several "serious problems" in that very short description. SSU is not the end-all to human knowledge, however i see far fewer arguable explanations, until some one starts placing or adjusting to BBT to make a point.

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BB theory, or that which is accepted scientific theory (so said), simply states that everything (that means everything) from a singularity which included this everything (including space) unexplainable began to expand at very great speeds away from a place that is not explainable (no center) and continues to this day. its said what formed from stuff inside that thing and as the new found space cooled matter formed, from the the new found gravity. originally or in the late 1920's this was thought to be about 3-5 billion years ago, but as known or now visible, this figure is 14.2 billion years ago.

 

rarely mentioned is the fact that there are alternative theory, many of which out date BBT, that are still very much considered. steady state or the theory that tries to explain things from an eternal existence or a version of this the most common.

 

Still very much considered? Please, its archaic, there is zero evidence for steady state, while a huge amount for big band. Steady state hasn't been seriously considered for decades.

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Tycho; yes, the theory SSU, is very much alive. checked Google, just to make sure with a million or so hits.

 

i have no personal or other reason not to accept BBT, but do so for the lack of logic, expansion and singularity the obvious. i have just as many problems with the more modern concept of SSU as they try to argue BBT with an SSU understanding. not possible and both have many principles which they agree on. i do get upset when a poster is told BBT is the only possible answer and by no mention of another gives a false impression.

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Well, theoretical physicists are starting to believe that the universe began, not with a giant explosion, but came into being out of nothing by two "membranes" of currently unknown nature rippling and colliding with each other, much like a fault in the earth's crust. Our universe sprang to life, kind of like a sound, only the "sound" is matter.

 

Understand? Didn't think so.

 

Anyway, some scientists believe that these "membranes" can be harnessed to actually create a universe of our own. This universe could be made in your back yard, and over billions of years, would expand to light years in radius, but not displace so much as a cubic inch of space in the surrounding universe(s).

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Well, theoretical physicists are starting to believe that the universe began, not with a giant explosion, but came into being out of nothing by two "membranes" of currently unknown nature rippling and colliding with each other, much like a fault in the earth's crust. Our universe sprang to life, kind of like a sound, only the "sound" is matter.

...

 

My impression is that the colliding branes model has pretty much gone out of style.

 

It was developed, oh roughly 5 years back, Steinhardt (Princeton) and Hurok (Cambridge) mostly. Attracted some attention and discussion, went thru some variations.

 

Made it into popular media some---Brian Greene level etc.

 

Now AFAICS pretty much ignored by professional researchers.

 

At the last major workshop about the beginnings of the universe where top string theorists and quantum gravitists met and presented work, the colliding branes scenario was not even represented

 

that was the 3-week workshop this January, less than three months ago, at the Kavli Institute for Theoretical Physics at Santa Barbara (directed by Nobelist David Gross).

 

If you want to know why colliding branes has essentially been dropped---what other models work better---or at least seem more attractive to the KITP people, let us know. I or somebody will try to answer.

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just another idea based on BB. although very few explain BB as an explosion, cannot give a location (my back yard) or give the cause (my experiment).

since the formulation of big bang itself, there have been countless ideas ranging the limits of an imagination. i am continuously amazed that with all the imagination that goes into such theory, why the simple phrase "always been" has been so hard to grasp. most all infer something else that would seem to have always been, why not the universe itself.

 

gypsy; w/o going into the subject "background radiation", we can assume anything giving this appearance as energy, is no older than the energy that gives us reflective sight. this means according to the theory or the given 14.2billion year old event, this energy radiation as well is not from creation, since that creation is continuing at a distance well beyond, no less than 28BLY to what some say is much further. our understanding of these seen observance and energy with out sight, 14.2 billion years old, are in each case not set in stone....yet.

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If you want to know why colliding branes has essentially been dropped---what other models work better---or at least seem more attractive to the KITP people, let us know. I or somebody will try to answer.

 

Go ahead. Tell me.

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...why the simple phrase "always been" has been so hard to grasp. most all infer something else that would seem to have always been, why not the universe itself.

...

 

you aren't as far out of line as you may suppose.

 

our idea of the past is based on physical models that can be TESTED IN THE PRESENT and then run backwards in time.

 

until 2001 there was a clear choice of model---einstein 1915 GR was the reigning theory of gravity---and the GR-based model that fit the data could only be run back some 14 billion years. The only model we had BROKE DOWN at the beginning of expansion.

 

Now there are quantized versions of the mainstream cosmological model which fit the data equally well but which run smoothly back in time to before the start of expansion.

 

so they don't break down.

 

At present there is no scientific reason to prefer one over the other, further tests need to be devised. At present there is no scientific reason to suppose that time evolution of the universe stops at some point as you go back.

 

there is no jumping off point where there is "Nothing" before it.

 

If Hawking books or other pop books have given you the impression that Science says that there is "Nothing" before 14 billion years, then my only advice is to throw the books out. They are obsolete, and possibly misleading.

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Stebbins had a question about various theories of what replaces the GR breakdown----why is 'colliding branes' gone out of fashion, what more promising models have replaced it.

 

Somehow Stebbins question went missing or I accidently jumped to the wrong thread. I dont know what to do about that. I will leave my answer here because conceivably it might be useful to this discssion.

 

Here is my reply about 'colliding branes' going out of style.

===

Other people may have different ways of responding to that request but my first reaction would be to ask you to google

"Kitp spacetime singularities"

 

that gives you the program of the 8-26 jan workshop at KITP about what are the most promising ways to resolve spacetime singularities, especially how to get over the bigbang singularity and conditions before it.

 

http://online.kitp.ucsb.edu/online/singular_m07/

 

Each talk there has VIDEO that you can download and most also have PDF of the lecturer's SLIDES.

 

You can form your own impression. Maybe I'm wrong! Maybe they do have a bunch of stuff focused on colliding branes!

I could easily have overlooked because it is a 3 week workshop with lots of talks and I'm a lot more excited by the approaches that have been making progress recently.

 

In what i heard of the workshop I only heard curt dismissal of colliding branes, or they just would not come up.

 

The problem with them, in a nutshell, is that the time-evolution thru the big bang is not DETERMINISTIC. there is a before sequence which is modeled and there is an after sequence, but they don't actually CONNECT. the theory waves its hands at that point:-)

 

the other models we are talking about evolve the quantum state of the universe in a smooth deterministic way

 

they also have run a bunch of computer models, simulating the time evolution of the quantum state thru the big bang, in a lot of different cases---different sizes, different matter content, different constants.

 

Nothing like that ever happened with the colliding branes thing, back a few years when some people were into looking at it, AFAIK.

 

But you can prove me wrong if you want. Look at the workshop menu and see if you can find were Steinhardt or Hurok invited?

did they come and present their ideas?

was there some discussion? did anybody sound enthusiastic? I will have a look too.

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Well, using the find feature, I couldn't find them.

 

But if what you say about them being invited means that this press conference is invitation only, that could pretty much explain it. They didn't express their ideas because they simply weren't invited, in which case the explanation was a simple injustice.

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Well, theoretical physicists are starting to believe that the universe began, not with a giant explosion, but came into being out of nothing by two "membranes" of currently unknown nature rippling and colliding with each other, much like a fault in the earth's crust. Our universe sprang to life, kind of like a sound, only the "sound" is matter.

 

Understand? Didn't think so.

 

:) I do. This is called "ekpyrotic". The papers, in case anyone is interested, are here:

 

1. C Seife, Big bangs's new rival debuts with a splash. Science 292: 189-190, Apr 13, 2001. "Ekpyrotic" model. 11 dimensions, 6 rolled up and safely ignored. In perfectly flat 5D space float 2-4D membranes. One is our universe, the other a hidden "parallel" universe. Random fluctuations cause hidden universe to shed membrane that floats to our universe with quantum fluctuations. Some of energy of collision becomes matter and energy in our universe. Removes need for inflation. Removes singularity of big bang, instead is a "platelike splash". Big bang and ekpyrotic have different gravity waves. If another membrane peels off of hidden universe, then would destroy ours on impact. http://www.arXiv.org/abs/hep-th/0103239

http://www.sciencemag.org/cgi/content/full/292/5515/189

2. Turok on ekpyrotic http://online.itp.ucsb.edu/online/colloq/turok2/

4. Veneziano G The myth of the beginning of time. Scientific American 54-63 May 2004 http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=00042F0D-1A0E-1085-94F483414B7F0000 Sciam article

 

I would be careful of the phrase "theoretical physicists are starting to believe "

 

Ekpyrotic was proposed by Turok. A FEW physicists are looking at it seriously. Veneziano is one. But this is still a small minority in the theoretical physics community. A very large problem is that ekpyrotic depends on String Theory, and ST is in trouble.

 

Anyway, some scientists believe that these "membranes" can be harnessed to actually create a universe of our own. This universe could be made in your back yard, and over billions of years, would expand to light years in radius, but not displace so much as a cubic inch of space in the surrounding universe(s).

 

That's not what I have read. Ekpyrotic means the destruction of our universe and the creation of a new one. We're going to need a citation for this paragraph, please.

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The problem with them, in a nutshell, is that the time-evolution thru the big bang is not DETERMINISTIC. there is a before sequence which is modeled and there is an after sequence, but they don't actually CONNECT. the theory waves its hands at that point:-)

 

the other models we are talking about evolve the quantum state of the universe in a smooth deterministic way

 

Sorry, but with quantum mechanics, NONE of the universe is strictly deterministic!

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