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View Full Version : Can Dark Energy Break the Speed of Light Barrier?



RalofTyr
2010-Jun-08, 05:14 AM
Will, one day, Dark Energy be so strong that it will move matter faster than the speed of light?

Geo Kaplan
2010-Jun-08, 06:16 AM
Will, one day, Dark Energy be so strong that it will move matter faster than the speed of light?

No finite amount of energy suffices to accelerate even a tiny mass to the speed of light, let alone faster than c. Whether the energy is Dark or Bright doesn't alter that limitation.

WayneFrancis
2010-Jun-08, 07:35 AM
Actually the better explanation is that nothing can move through space faster then c. Dark Energy doesn't move stuff through space but actually creates new space and drags what is already in it along with it so it does NOT violate special relativity. There are objects in the universe that are currently receding at a rate faster then c.

Geo Kaplan
2010-Jun-08, 07:48 AM
Actually the better explanation is that nothing can move through space faster then c. Dark Energy doesn't move stuff through space but actually creates new space and drags what is already in it along with it so it does NOT violate special relativity. There are objects in the universe that are currently receding at a rate faster then c.

Yes, it is absolutely important to distinguish expansion of space itself from motion of matter through space, and to acknowledge that the truth of your last sentence does not rely on Dark Energy (I'm not implying that you said so; just clarifying things for the OP).

sirjon
2010-Jun-08, 07:55 AM
Actually the better explanation is that nothing can move through space faster then c. Dark Energy doesn't move stuff through space but actually creates new space and drags what is already in it along with it so it does NOT violate special relativity. There are objects in the universe that are currently receding at a rate faster then c.
"..creates new space" sounds similar to the Steady State Theory (Bondi-Gold-Hoyle), except 'it is space that being created'. Is this a 'fact' or only a hypothesis? Thanks.

tnjrp
2010-Jun-08, 08:08 AM
I don't see how it sounds "similar" to Steady State at all since it's the exact opposite to "steady". But be that as it may, observations do strongly indicate that space is indeed exapanding and it also looks to do so at an increasing rate.

"Light barrier" only properly applies to information transfer rate in any case.

Geo Kaplan
2010-Jun-08, 08:44 AM
"..creates new space" sounds similar to the Steady State Theory (Bondi-Gold-Hoyle), except 'it is space that being created'. Is this a 'fact' or only a hypothesis? Thanks.

As tnjrp says, it is extremely well supported by observation. Google terms like "redshift" "universal expansion" "inflation" etc.

astromark
2010-Jun-08, 08:47 AM
I am concerned that we do not all understand things in a similar manor...
The following as best as I can decipher the ' Mainstream View.'
" Extensive and repeated observations have drawn astronomers to except that
The universe that is not directly effected by gravity associated with galactic groupings nebulocity or gravity wells ... is expanding."
That it is doing so at a increasing rate as it does so. That, that rate seems to have been slower some time ago.
The UNKNOWN force that has been attributed for this has been called DARK ENERGY.
I am not alone in suggesting to you that we do not know the ' Why ' or ' What ' So its name is Dark Energy.
As for it having a velocity... that would be unknown. As none of us have the foggiest idea where to find any of this Dark Energy.
We are however absolutely certain of it driving the expansion we observe.
NOW... Just in case some of what I have said is a little confusing... Great. welcome to the cutting edge of cosmology.

sirjon
2010-Jun-11, 07:57 AM
As to the older notion that 'gravity keeps galaxies together (bounded together)', today's science suggests that galaxies are moving away from one another. My question is, as galaxies move away from one another, the gravitational balance no longer holds, that the old notion is a little bit inaccurate? What are the reasons behind this phenomenon? Does the mainstream is keeping up with these new developments in astronomy?

tnjrp
2010-Jun-11, 08:11 AM
Gravity still holds sway, just as it did before the discovery of the phenomenon dubbed "dark energy". Galaxies are moving away from each other only on a scale where gravity becomes negligible. It is however possible that the dark energy will eventually overcome gravity at smaller and smaller ranges. In fact it is possible that it will eventually become so overpowering that it will rip everything apart down to the smallest existant level. This last scenario is called the Big Rip.

sirjon
2010-Jun-11, 08:29 AM
Gravity still holds sway, just as it did before the discovery of the phenomenon dubbed "dark energy". Galaxies are moving away from each other only on a scale where gravity becomes negligible. It is however possible that the dark energy will eventually overcome gravity at smaller and smaller ranges. In fact it is possible that it will eventually become so overpowering that it will rip everything apart down to the smallest existant level. This last scenario is called the Big Rip.
A follow-up question? What will happen during and after the Big Rip? I'm just curious. Thanks

tnjrp
2010-Jun-11, 09:11 AM
HTH:
http://en.wikipedia.org/wiki/Big_Rip

It has been postulated, most notably by Baum & Frampton in their cyclic cosmology model, that the Big Rip event would enable the universe to "come back empty" for a new cycle:
http://en.wikipedia.org/wiki/Cyclic_model#The_Baum.E2.80.93Frampton_model

It must be noted that these latter are quite hypothetical models, while the dark energy phenomenon itself is by and large accepted by the physics community AFAIK.

Cougar
2010-Jun-11, 01:20 PM
As none of us have the foggiest idea where to find any of this Dark Energy.
We are however absolutely certain of it driving the expansion we observe.

1. I don't think we should claim to be "absolutely certain" of anything. Science always allows for new observations and new explanations.
2. Dark energy has been invoked as an 'explanation' of the acceleration of the expansion, not the expansion itself. It may be found to be related or even intimately related, but we are currently at a loss to understand exactly what's going on in this area.

antoniseb
2010-Jun-11, 01:29 PM
What will happen during and after the Big Rip?

We are not certain that there will be a Big Rip. The nature/behavior of Dark Energy is still being determined.

astromark
2010-Jun-13, 08:19 PM
Cougar., My first paragraph covers your points... I agree with you.

I like this analogy... its not expected you would all agree. In the thinking of explaining this observed expansion I like to give this.
A long length of elastic cord. Laid out before you and not stretched at all. Marked in equal increments to indicate points along the strip.
As your flexible band stretches the increments at each end travel much faster than near the center.
Play that out for a while and your understanding of expansion of space gets clearer... ( well it works for me )
Hands on explanations you can show school children do work towards understanding the universe. The elastic band represents empty space.