No Big Bang? Quantum equation predicts universe has no beginning

[RecoveringYuppy]

if this proves correct a lot of creationists are going to be seriously bummed...

There is nothing here they can't misunderstand to their liking. They should have been bummed all along because the GR based big bang theory wasn't powerful enough to declare that the beginning of this universe was a true beginning for everything.

ETA: Not to mention that the Bible getting one yes/no question right is hardly anything to brag about.

 

[Puppycow]

So as a layman, I don't know enough to comment on this theory.

Does anyone know enough to say whether this is legit (a reasonable alternative theory) or just more cranks?

 

[ctamblyn]

It seems legitimate, although not necessarily correct (if that makes sense). From what I can tell, they've modified a specific aspect of GR to incorporate an approximation of certain quantum effects, so it boils down to whether that approximation is justified.

ETA: In a little more detail, there is an equation you can derive in GR (the Raychaudhuri equation) which is a key component in the proofs by Penrose and Hawking which predict that spacetime singularities will exist, including the initial big bang singularity. They have modified that equation by including an approximation of certain quantum effects, and have shown that this modification prevents those singularities. As a special case, they have shown that with this modification you can trace back particle world-lines in an expanding universe arbitrarily far into the past (in terms of proper time).

(That based on my reading. Someone more knowledgeable please correct me if I'm wrong.)

 

[Darwin123]

No. Hoyle's Steady State theory required the continuous creation of matter at the rate of one hydrogen atom per cubic metre per 10¹⁰ years as the Universe expands. This would have implications such as radically violating laws of physics such as conservation of mass and energy.

Of course, Steady State also cannot account for the CMB

So tell me what was different about photons? Why didn't his theory also include the generation of one photon of black body radiation per year with a black body spectral resolution?

One can hypothesize the generation of any particle at all. So one can fit the data by adding continuous creation of some arbitrary component. Maybe photons pop out of nowhere in a way that 'explains' the Cosmic Black Body Background. Maybe nucleii other than the proton appear occasionally. One can explain the element distribution. Etc.

This by itself doesn't make a useless model. However, it is not useful as a generalized theory. It is just a phenomenological fit.

The steady state model may still be correct. However, it involves busting conservation of energy, conservation of lepton number, conservation of baryon number, etc.

Scientists today are trying to build a general model of the cosmos. Scientists have a good fit to the data. They are looking for a physical theory that explains the success of the Big Bang model.

 

[SezMe]

Does anyone know enough to say whether this is legit (a reasonable alternative theory) or just more cranks?

It seems legitimate, although not necessarily correct (if that makes sense)

ctamblyn is right. Physics Letters B is a mainline, peer-reviewed publication so this is not crank stuff. However, it is subject to continued review and correction so it is not the last word....like all good science.

But this is small potatoes. "The tide comes in, the tide goes out" still have not been explained. Tackle THAT one, my physics friends.

 

[Cl1mh4224rd]

This was brought up on Slashdot and someone asked a rather simple question, which I'll paraphrase here because I don't know nearly enough about this topic to read the paper and come up with an answer:

If the universe is infinite, why are there still stars?

Basically, where does the hydrogen that we observe being fused in stars today come from in an infinite universe? Wouldn't it have all been fused into heavier elements?

 

[smartcooky]

This was brought up on Slashdot and someone asked a rather simple question, which I'll paraphrase here because I don't know nearly enough about this topic to read the paper and come up with an answer:

If the universe is infinite, why are there still stars?

Basically, where does the hydrogen that we observe being fused in stars today come from in an infinite universe? Wouldn't it have all been fused into heavier elements?

If the universe is infinite, wouldn't there be an infinite supply of hydrogen?

 

[SezMe]

Yes, if the universe were infinite, there would be an infinite number of stars burning an infinite supply of hydrogen ... which would create an infinite amount of heavier elements which would create an infinite number of super nova which .....

When the mathematical concept of infinity collides with the physical universe, all hell breaks loose, including logic. The physical sciences deal with known observables, which don't include "infinity".

 

[Quinn]

When the mathematical concept of infinity collides with the physical universe, all hell breaks loose, including logic. The physical sciences deal with known observables, which don't include "infinity".

"Ford, there's an infinite number of monkeys outside who want to talk to us about this script for Hamlet they've worked out." -- Douglas Adams

 

[ctamblyn]

This was brought up on Slashdot and someone asked a rather simple question, which I'll paraphrase here because I don't know nearly enough about this topic to read the paper and come up with an answer:

If the universe is infinite, why are there still stars?

Basically, where does the hydrogen that we observe being fused in stars today come from in an infinite universe? Wouldn't it have all been fused into heavier elements?

In the article from the OP, as I understand it anyway, the universe has only been producing stars for a finite amount of time. If you go back 13.7 billion years, it will still in this suggested model have been in an incredibly dense and high-temperature state, with a period after that in which baryogenesis and later star and galaxy formation occurred just as in the standard model. It's just that there's no singularity before that hot, dense state: you can extend timelike curves (i.e. follow the trajectories of test particles) back in time forever.

 

[sphenisc]

It seems legitimate, although not necessarily correct (if that makes sense). From what I can tell, they've modified a specific aspect of GR to incorporate an approximation of certain quantum effects, so it boils down to whether that approximation is justified.

ETA: In a little more detail, there is an equation you can derive in GR (the Raychaudhuri equation) which is a key component in the proofs by Penrose and Hawking which predict that spacetime singularities will exist, including the initial big bang singularity. They have modified that equation by including an approximation of certain quantum effects, and have shown that this modification prevents those singularities. As a special case, they have shown that with this modification you can trace back particle world-lines in an expanding universe arbitrarily far into the past (in terms of proper time).

(That based on my reading. Someone more knowledgeable please correct me if I'm wrong.)

Does this apply to black hole singularities too?

 

[ctamblyn]

Does this apply to black hole singularities too?

Yes, I would think so (assuming it is valid at all).

 

[Butter!]

I assume this means that we're now free to go about without pants?

YES!

Finally. *skips about joyously*

I love science.

 

[smartcooky]

In the article from the OP, as I understand it anyway, the universe has only been producing stars for a finite amount of time. If you go back 13.7 billion years, it will still in this suggested model have been in an incredibly dense and high-temperature state, with a period after that in which baryogenesis and later star and galaxy formation occurred just as in the standard model. It's just that there's no singularity before that hot, dense state: you can extend timelike curves (i.e. follow the trajectories of test particles) back in time forever.

So, they are saying that the universe just sat there, a big ball of dense hot stuff, stretching back for an infinitely long time, until suddenly, 13.798±0.037 billion years ago, it started expanding /inflating.

If so, I find that more difficult to understand/believe than the big bang.

 

[ctamblyn]

So, they are saying that the universe just sat there, a big ball of dense hot stuff, stretching back for an infinitely long time, until suddenly, 13.798±0.037 billion years ago, it started expanding /inflating.

If so, I find that more difficult to understand/believe than the big bang.

I'm not yet completely clear on what their universe looked like for what you could call "t < 0", but it was probably not a static primordial atom. I think that it's size/scale factor was increasing for all that time, so that the scale factor approaches zero asymptotically as t goes to negative infinity, but at this point I'm not 100% sure.

 

[Manopolus]

I could have told you that. It's sort of an identity statement.

If the big bang was at the beginning of existence, then time didn't exist at the "time" of the big bang... It all decays into complete nonsense at that point. Actually, it's also the same from a creationist perspective (note: not my perspective, just thinking freely here) -- turtles all the way down.

When you reach the limits of your understanding what you get is that it is what it is. I'd say it's a complete failure to learn anything new, judging by the results.

 

[ctamblyn]

They're definitely saying something important: namely, that quantum effects effectively eliminate singularities from GR. Whether their argument is good enough remains to be seen.

They also claim that their model predicts the correct value of the cosmological constant. However, their derivation depends on making extra assumptions (like a non-vanishing but small graviton mass) which were not required for their analysis of singularities.

 

[smartcooky]

I'm not yet completely clear on what their universe looked like for what you could call "t < 0", but it was probably not a static primordial atom. I think that it's size/scale factor was increasing for all that time, so that the scale factor approaches zero asymptotically as t goes to negative infinity, but at this point I'm not 100% sure.

 

[ctamblyn]

Theirs wouldn't be the first such model. The scale factor for the de Sitter universe goes as exp(Ht), and such a universe has no beginning:

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

 

[progressquest]

I am having a hard time understanding most of this. I mean, most of the words are easy enough to understand, but I just don't see the significance. It's probably just that I don't have the requisite math skills to grok this (or is it maths skills?).

All I know is that I am getting strange looks now, and am starting to think that the pants comments were not serious.