Age of the Universe

[CDarwin]

If I had to put a single number down as the age of the universe, what would be the safest one as of the current consensus?

 

EDIT: You know, this might go in "homework help." I'm putting this in a scholarship essay and I just want a safe number.

[Klaynos]

13.7bn years.

 

http://en.wikipedia.org/wiki/Age_of_the_universe

 

and maybe:

 

http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/338655&erFrom=7513586550270237190Guest

 

If you can decipher it will give you something you can reference well...

[Reaper]

13.7 billion years, accurate to about +/- 200 million years. Also, make it clear that a big bang does not mean an explosion.

[CDarwin]

Thank you. I suppose I should have just gone with the Wikipedia but I wasn't totally sure. I'm just making a passing reference so it isn't horribly important to my paper or anything, but I don't want to look stupid in case anyone who knows what they're talking about with cosmology happens to read it.

[thedarkshade]

If not an explosion, than what?

[Klaynos]

If not an explosion, than what?

 

The creation of everything from nothing all at once....

[SkepticLance]

If not an explosion, then what?

 

Depends on whose theory you subscribe to. Lots of ideas exist. Possibly a brane collision??????

[Martin]

13.7 billion years, accurate to about +/- 200 million years. Also, make it clear that a big bang does not mean an explosion.

 

I agree.

Among working cosmologists, I have never heard or read

the big bang described as an explosion.

that image just would not make sense

 

an explosion requires some surrounding space for stuff to explode OUT INTO.

 

in standard professional cosmologist view, there is no surrounding space.

so there is nothing that resembles an explosion

 

=============

the big bang event is modeled in various ways

in a lot of recent research papers it is modeled as a bounce

where space is collapsing and reaches a critical density (where gravity repells due to quantum corrections) and then starts expanding.

 

I guess there are a hundred or so research papers that model it along those lines and study the consequences. some computer modeling. some analytic.

===============

 

ScepticLance mentioned another approach----"brane collision"

many papers written about that scenario too.

I haven't read much about that scheme, but it is certainly out there!

 

================

 

and in a lot of older work they just leave it as a GAP where the model doesnt extend and they don't yet have an idea what was happening. the gap or glitch in the model (where it stopped working) was called the "singularity"

 

I'd say the trend now is away from that though. the trend is to fix the gap, resolve the "singularity"---in other words use an improved model to get rid of it.

================

 

another scenario that gets rid of the singularity is called "eternal inflation" or "chaotic inflation". it impresses me as pretty speculative and unable to predict anything. too hand-wavy. but that is just my opinion.

================

 

among professional cosmologists---at the big international conferences like GRG (General Relativity and Gravitation, held every three years, this year in Sydney)----what is getting the most attention is the LQG bounce picture.

 

Largely, I think, because you can calculate stuff like big bang nucleosynthesis, abundance of elements, structure formation---or anyway they are beginning to do that---and the quantized model looks very much like the standard bigbang/expanding universe model that cosmologists are used to dealing with.

 

The only main difference is that the model doesn't break down as you go back in time.

there is no place where you have to give up in defeat and say "at this point everything was created out of nothing"

 

that makes the professional astrophysicists happy, so if you look at the line-up of invited speakers at the next international conference having to do with general relativity and cosmology it will probably have a bunch of LQG speakers.

 

my impression anyway. the next one is in India, December I think. we could check just to make sure my impression is right.

Yeah. Here are some links---I make a post about the conference. Programme shows how things are going.

http://www.scienceforums.net/forum/showthread.php?t=29324

==========

exciting times in cosmology, these days.

a lot of rapid change

[thedarkshade]

I agree.

Among working cosmologists, I have never heard or read

the big bang described as an explosion.

that image just would not make sense

 

an explosion requires some surrounding space for stuff to explode OUT INTO.

 

in standard professional cosmologist view, there is no surrounding space.

so there is nothing that resembles an explosion

 

=============

the big bang event is modeled in various ways

in a lot of recent research papers it is modeled as a bounce

where space is collapsing and reaches a critical density (where gravity repells due to quantum corrections) and then starts expanding.

 

I guess there are a hundred or so research papers that model it along those lines and study the consequences. some computer modeling. some analytic.

===============

 

ScepticLance mentioned another approach----"brane collision"

many papers written about that scenario too.

I haven't read much about that scheme, but it is certainly out there!

 

================

 

and in a lot of older work they just leave it as a GAP where the model doesnt extend and they don't yet have an idea what was happening. the gap or glitch in the model (where it stopped working) was called the "singularity"

 

I'd say the trend now is away from that though. the trend is to fix the gap, resolve the "singularity"---in other words use an improved model to get rid of it.

================

 

another scenario that gets rid of the singularity is called "eternal inflation" or "chaotic inflation". it impresses me as pretty speculative and unable to predict anything. too hand-wavy. but that is just my opinion.

================

 

among professional cosmologists---at the big international conferences like GRG (General Relativity and Gravitation, held every three years, this year in Sydney)----what is getting the most attention is the LQG bounce picture.

 

Largely, I think, because you can calculate stuff like big bang nucleosynthesis, abundance of elements, structure formation---or anyway they are beginning to do that---and the quantized model looks very much like the standard bigbang/expanding universe model that cosmologists are used to dealing with.

 

The only main difference is that the model doesn't break down as you go back in time.

there is no place where you have to give up in defeat and say "at this point everything was created out of nothing"

 

that makes the professional astrophysicists happy, so if you look at the line-up of invited speakers at the next international conference having to do with general relativity and cosmology it will probably have a bunch of LQG speakers.

 

my impression anyway. the next one is in India, December I think. we could check just to make sure my impression is right.

Yeah. Here are some links---I make a post about the conference. Programme shows how things are going.

http://www.scienceforums.net/forum/showthread.php?t=29324

==========

exciting times in cosmology, these days.

a lot of rapid change

 

It's kinda strange why all those graphs and maps related to Big Bang progress only on one side! According to what I've read and seen about Big Bang, the very initial ancient state before or right at the Big Bang was infinite density and zero volume. This latter one has been having some hiccups quiet frequently, but what I'm trying to say is that at the beginning was only a point (infinitely dense and zero volume). And a point is circular. So any progress (like explosion or better to say expansion) done to this point should have gone steady to all directions. So why all maps and graphs (even Wiki's) progress in one direction? what about the other part? Excluded from universe???

 

The creation of everything from nothing all at once....

 

So you agree that universe was created from nothing (volume zero), because many don't. So creationism or eternal universe? Which you think is the one?

[Martin]

It's kinda strange why all those graphs and maps related to Big Bang progress only on one side! ...

 

They DON'T all progress on only one side. Some diagrams of Big Bang show contraction coming in on one side, a bounce, and expansion on the other side.

 

These are new. I think the reason the older maps all stop as you go back to Big Bang is because they didn't have any idea. If you don't know, you just stop and LEAVE THE MAP UNFINISHED.

 

So why all maps and graphs (even Wiki's) progress in one direction? what about the other part? Excluded from universe???

 

Those maps and graphs are incomplete. The scientists' work is unfinished.

 

You have not seen all maps and graphs. You should not rely on Wiki. It is better to rely on recent journal articles in professional peer-reviews journals, like Physical Review Letters, and Physical Review series D

Also Nature Physics is a peer-review journal with high reputation.

 

There are many models which go back before Big Bang.

For now the problem is to decide which is most likely to be the right one.

 

After professionals decide which to prefer then they will gradually get the idea out into popular media and add it to Wikipedia. But now I think the popular media do not have this

 

If you have no other knowledge, then you should tend to pay attention to articles from the last few years which other professionals have cited in their references----journal articles with high citation counts.

 

If you want some links to highly-cited journal articles, please let me know and i can post some for you.

[thedarkshade]

Hi Martin,

 

It might sound like stupid but I got this way of looking Big Bang from a different point of view! And there are some things that make me think tightly!

 

So at first there was nothing, just an infinitely dense point. Then there was this energy (dark energy) which made this point expand and accelerate! Normally, this energy should have been given uniformly to that point, so all its sides expand equally, and as it expanded (and expands) in frictionless conditions then it should go one forever.

 

But I always get stuck to the same think! If this energy (dark) is given uniformly so this dot expands equally to all its sides, then why aren't its sides completely the same? The couldn't possible be anything to make these sides change and so differ because there was nothing before!

 

And one more thing. Dark matter is just like a gum that acts between everything in the universe (stops them from getting all away). And if there comes a state when dark energy shall decrease, will then dark matter bring all the universe back to that infinitely dense point??

Strange huh?!

 

Thnc for ur help.

[Cap'n Refsmmat]

But I always get stuck to the same think! If this energy (dark) is given uniformly so this dot expands equally to all its sides, then why aren't its sides completely the same? The couldn't possible be anything to make these sides change and so differ because there was nothing before!

Quantum effects. Anything with heat (energy) jitters around randomly (that's what heat is). Random clumps form.

[Mr Skeptic]

These are new. I think the reason the older maps all stop as you go back to Big Bang is because they didn't have any idea. If you don't know, you just stop and LEAVE THE MAP UNFINISHED.

 

Well, the really old maps had pictures of sea monsters and space sharks wherever they didn't know what was there. But they stopped doing that because it looked silly when there turned out to be no monsters there.