Discussing the Big Rip Theory: Have You Heard About It?

[Joe L. Ogan]

Somewhere, I read about the "Big Rip Theory". Has anyone here heard about the Big Rip Theory? Joe L. Ogan

 

[Chronos]

Yes. The 'big hit' is the current favorite theory of how the moon formed. It makes good sense when you look at geological and moon rock studies. The chemistry of moon rocks is unlike that of any other body in the solar system save earth.

 

[Joe L. Ogan]

Hi, I should have asked about the "Big Rip" Theory. My apologies. Joe L. Ofan

 

[George Jones]

I changed the title of the thread from "Big Hit Theory" to "Big Rip Theory". Chronos posted when the thread still had its original title.

I think the paper that first really pushed this idea was

http://arxiv.org/abs/astro-ph/0302506.

For a non-technical exposition, read

http://www.space.com/scienceastronomy/big_rip_030306.html.

 

[marcus]

Joe, this is just a side comment: look at the DATES on the material that George just gave you links to.

I haven't heard much about "big rip" scenario since like 2005.

I remember hearing a lot about it back in 2003-2004 but the buzz died down some since then.

The present model that astronomers use, which seems a good fit to the data that has come in since 2005 (eg from spacecraft like WMAP) so far, does not do a big rip. It has accelerated expansion but the acceleration is rather gentle and doesn't disassemble our galaxy, or our solar system, or anything on that scale.

It is always possible that the data is wrong, and that future data will indicate different cosmic parameters and a different expansion history, and the "big rip" scenario could make a comeback and become a fashionable idea once more.

 

[Joe L. Ogan]

Joe, this is just a side comment: look at the DATES on the material that George just gave you links to.

I haven't heard much about "big rip" scenario since like 2005.

I remember hearing a lot about it back in 2003-2004 but the buzz died down some since then.

The present model that astronomers use, which seems a good fit to the data that has come in since 2005 (eg from spacecraft like WMAP) so far, does not do a big rip. It has accelerated expansion but the acceleration is rather gentle and doesn't disassemble our galaxy, or our solar system, or anything on that scale.

It is always possible that the data is wrong, and that future data will indicate different cosmic parameters and a different expansion history, and the "big rip" scenario could make a comeback and become a fashionable idea once more.

Thanks. I am just a neophyte in the Cosmology area and am just trying to learn. I came across the "Big Rip" theory while just browsing and thought I would inquire what others thought. Thanks for your information. Joe L. Ogan

 

[Ich]

It is always possible that the data is wrong

To be fair, the data doesn't have to be wrong. It just places a possible Big Rip in the far future, and is consistent with the null hypothesis "there will be no Big Rip".

 

[friend]

I understand that inflationary expansion is powered by the vacuum energy. Inflation was caused by a fall in vacuum energy. And some think we may be in a false vacuum state now that may one day fall and create a new round of inflationary expansion. Has there been any progress in proving or disproving this possibility? I would think that our problem with the cosmological constant would suggest we really don't know at this point how to calculate whether we're in a false vacuum or not.

 

[Deuterium2H]

The general consensus amongst Cosmologists and Astrophysicists is that the "Big Rip" is nonsense. It made a bit of a splash back a few years ago, and the media ran with it. And, typical of mainstream media, they made way more out of it, and implied it was a serious theory...which it was not.

Basically, it violates all sorts of laws of Physics. Specifically, it requires that the Cosmological Constant varies with time...which is NOT accepted by the majority of specialists in the field, nor is it supported by observational evidence. As far as we can be certain of things, the Cosmological constant is a constant, and does not vary with time.

Given that the CC does not vary (or increase) with time, then there is no way for "dark energy" to overcome the forces of bound structures, such as galaxies, solar systems, planets, people, molecules, atoms, etc.

 

[NEILS BOHR]

The Big Rip is an extreme scenario that supersedes that of a Big Freeze. Both of them are possible consequences of an ever expanding universe. While the Big Freeze can take place if the forces that are believed to govern the current rate of expansion are constant, the Big Rip will happen if the forces that favor expansion are further increased.

 

[bapowell]

And some think we may be in a false vacuum state now that may one day fall and create a new round of inflationary expansion.

This is slightly incorrect. If the universe is in a false vacuum state, then it will inflate (a false vacuum is a state with nonzero vacuum energy -- the stuff that drives the accelerated expansion.) If this state happens to decay in the future, one of two outcomes is possible: 1) it decays to a true vacuum and inflation stops or 2) it decays to another false vacuum of lower energy and continues to inflate at slower rate. At the present time, cosmologists don't know whether the universe exists in a false vacuum state.