Is There a Giant Black Hole at the Centre of the Universe?

[Eh]

Andrei Linde posted a paper a while back on the subject of dark energy. Under some models of super gravity, the dark energy (assumed to be vacuum energy from QM) driving the acceleration would not continue to increase as time goes by. Instead, the value would eventually stop increasing, and then drop towards zero. But it wouldn't stop there - as the value would begin to take on a negative value. An omnipresent dark energy with positive preasure would then cause the universe to contract.

There was a topic about this on the old PF, but I'll see if the article is still lying around somewhere. Does anyone here know anything about super gravity?

 

[M. Gaspar]

Eh...

From Oxford Dictionary of Science (1996) ...

Supergravity: A unified-field theory for all the known fundametal interactions that involves supersymmetry. Supergravity is most naturally formulated as a Kaluz-Klein theory in evleven dimensions. The theory contains particles of spin 2, spin 3/2, spin 1, spin 1/2 and spin 0. Although supersymmetry means that the infinities in the calculations are less severe than in other attempts to construct a quantum theory of gravity, it is probable that supergravity still contains infinities that cannot be removed by the process of renormalization. Is is thought by many physicicts that to obtain a consistent quantum theory of gravity one has to abandon quantum field theories, since they deal with point objects, and move to theories based on extended objects, such as superstrings and supermembranes, and therefore that supergravity is not a complete theory of the fundamental interactions.

Eh: I hope that was helpful. And if you can come through with recent data that supports the eventual collapse of the Universe, I will be grateful.

 

[Brad_Ad23]

Yes, supergravity theories are nice and all, however they have shown to be inadequate, which is why most of the research is now turned to the current big 3: M-Theory, Loop quantum gravity, and Twistor Theory (to a lesser extent than the other two)

 

[Mr. Robin Parsons]

Try this one...

https://www.physicsforums.com/showthread.php?postid=11626#post11626"

 

[Eh]

For reference, here is the article I was talking about: http://news.bbc.co.uk/2/hi/sci/tech/2346907.stm

 

[M. Gaspar]

Eh...

I can't tell you how thrilled I am with the article you referenced.

I agree with it somewhat, except I would not use the phrase that the "Dark Energy" will turn "negative"...but believe that perhaps there will be a "trigger" (overall temperature drop, perhaps) that will cause the "Dark Energy" to convert to "Dark Matter" to start the implosion process of the Universe.

And while I agree with Prof. Linde's conjecture that the Universe will collapse, I do NOT agree that it is "doomed to disappear."

In fact, might it not be possible that it would contract to a singularity that, in turn, would burst forth into the NEXT "Big Bang".

This is a "Life Cycle" that I can live with...and that the Universe can LIVE WITH TOO!. Expanding out into a frigid eternity doesn't even appeal to the cosmologists who are proposing it. It is much more satisfying (to ME, at least) to believe the Universe is an "eternal entity of energy" that enjoys infinite incarnations via the expansion/contraction model.

In fact, as I have said before, I believe the Universe is a living, conscious Entity that evolves -- as we do -- via infinite incarnations. [?] [?] [?] [?]

But that's off topic.

 

[Eh]

The reference to negative energy seems to actually be about preasure. Normal matter has positive preasure, while the dark energy of the vacuum is said to have negative preasure and so does not gravitationally attract. The transformation would be that negative preasure becoming positive.

 

[Messiah]

Originally posted by KL Kam
the universe doesn't have a centre

Using any given point in space as an X,Y,Z axis, one may theoretically extend equidistant lines to infinity through the limitless spectrum of polar coordinates. The procedure inscribes a sphere which theoretically encompasses the Universe. By definition, the selected point is the center of that sphere - and the center of the Universe. Since the same can be done for all points, it seems every position in the cosmos is its center.

 

[Mr. Robin Parsons]

The center of the universe is everywhere, just that our limited perception of it allows us only to see it somewhere.

It is because the light is invisible to our eyes, all we ever see is light when it is interacting with matter, NOT when it is traveling from source, to surface, rebound, back towards surface or source, ad infinitum, sorta, it wears out in time due to interactive energy loses, hence, dark, if not replaced by more light!

It is a constant activity