Thread: Dark energy and the expanding universe

Please forgive me if this sounds stupid.If dark energy is pushing the universe to expand at a accelerating rate and as it gets bigger the more dark energy exist to push the universe apart further and faster. Could this lead to light speed being broken as the stars are pushed away at speeds faster than light. Making the stars we see now disappear from view (or could it have already happened at lights source) Theoretically speaking? Or do I have a bad understanding of the theories involved?

From how I understand it, it's not that galaxies are moving through space, it's that the space itself is expanding.

To use the balloon analogy, draw dots on a balloon and blow it up, the dots move away from each other but they don't actually move through the rubber of the balloon surface. If that makes sense?

Admittedly, I'm not an expert so I could be completely wrong, it's just how I think I understand it so far.

Or could the universe be a speck on a toroidal vortex expanding on the way to the outer edge of the vortex before it stops and contracts in to the centre?

Daecon. I don't know. Would the dots not still be moving away from each other and away from the centre of the ballon to expand. I just trying to get a grasp, I must say I don't have a qualified understanding of all theories

Originally Posted by ADD Dave

Or could the universe be a speck on a toroidal vortex expanding on the way to the outer edge of the vortex before it stops and contracts in to the centre?

That sounds like the Big Crunch scenario, one of the possible ultimate fates of the Universe.

Originally Posted by ADD Dave

Daecon. I don't know. Would the dots not still be moving away from each other and away from the centre of the ballon to expand. I just trying to get a grasp, I must say I don't have a qualified understanding of all theories

Well there's no real "center" of the balloon's surface (we're only using the rubber membrane as our analogy for the Universe, not the air inside the balloon). the idea is, if you go far enough in one direction you'll circle back around and end up in your original position.

Even if the dots on the balloon (or the galaxies in the Universe) were moving away from each other faster than light speed, those galaxies are not actually moving through space - it's just the space in-between them expanding. I don't believe there's a theoretical limit as to how fast empty space can expand, only a limit as to how fast physical matter and energy can move through space.

Cheer cheer I think a get it. Does that mean that although the empty space between two points in the universe are expanding and the light would still have to travel these greater distances limited by the speed of light that eventually the stars as we see them will cease to shine. Or could the laws governing the speed of light be dynamic?

I think (not certain, will have to wait for an actual expert to respond) that the "inflation" stage at the beginings of the Universe was a brief period of time where space actually was expanding faster than light speed.

Because of this, light/electromagnetic energy in one part of the Universe will never, ever be able to reach the region of another part of the Universe, and so you can conclude that these separate regions will never be able to interact with each other.

I think (again not sure) that if space ever again expanded faster than light speed, distant stars would appear to redshift into nothingness instead of "blink" out.

http://www.phinds.com/balloonanalogy/

The Balloon Analogy is a simpleminded way to HELP describe (but not completely describe) two facts of cosmology that are difficult for many people to see, namely that the universe is expanding uniformly and that there is no center.

The analogy is disliked (often intensely disliked) by serious physicists because it causes at least as much confusion as it is intended to avoid and is often badly misunderstood and/or incorrectly extrapolated to ridiculous points of view.

Presented here is the simpleminded balloon analogy and then a discussion of cosmology and why the balloon analogy is so flawed. There are many other aspects of cosmology that can get drawn into discussions of the balloon analogy, but I have for the most part resisted discussing any that are not immediately relevant to the analogy, lest I get carpal tunnel syndrome while having this page turn into a textbook on cosmology (which I am not qualified to write anyway). I have given a couple of links at the bottom of the page to further discussions.

more at link.

I thought one of the main foundations of the Expanding Universe theory is that the light (radiation) from objects moving away from us has redshift (z-) values, compared to our standard star's light. Because high redshift should indicate very distant objects the idea of quasars being extremely distant, faint objects arose. However there seems to be a problem with the assumption. Several astronomers have found groupings of objects which have a wide range of z-values. An example is the quasar (z=2.114) in front of NGC 7319 (z=0.0225). The late Halton Arp disputed accepted belief and considered red-shift may indicate the energetic emergence of daughter galaxies. Their brightness increases as their redshift reduces.

Many thanks for all replies. Looked up redshift (left school @ 15). I'm processing but don't have much time to study ATM as I have to be up in 5 hours for another day. Will process info ASAP. Many thanks

I disagree with others. I do not see the expansion of the universe having a limited speed of expansion. The speed of light could not be broken, however the amount of space that exists between two points could expand at such a rate where light would not reach from one to the other in the lotted amount of time.

Strange, invisioning a civilization some 5 billion+ years in the future turning to the heavens and finding no galaxy's beyond there own. They will come to the wrong conclusion that the universe is void & have a skewed view of reality, simply because they are unable to see the light trying to overcome expansion to reach them. A universe that is no more than 100-200 million light years across.