The universe is expanding and that expansion is speeding up. What is...?

Question

What is left in the space where the galaxies once were? A dent? And what is causing the expansion to speed up instead of slowing down? Is there not enough gravity trickling in to our universe?

Answer 1

Hi NY NY 2

Quite a hodge podge of answers above. let me see if I can clear some misconceptions up for you:

First, the evidence. About 8 years ago two separate independent groups announced measurements of the brightness of supernova at a redshift z=1. (Cosmologists use redshift factor "z" to show how far away something is in space-time by designating how far light from the object is redshifted by the time it arrives at earth. The redshift is due to the expansion of the intervening space. Redshift z=1 corresponds to a distance where the wavelength of light has been redshifted to double its original wavelength.). These results indicated that the universal expansion was accelerating. Since that time the results have been confirmed, and supporting evidence was found in the detailed mapping of the microwave background.

Surprisingly (you might think) it is very easy to modify the equations which describe the universe's evolution to make the expansion accelerate. The reason for this is that Einstein originally included such a factor in his early equations.

Briefly, the equations for the universe at large scale talk about gravity and pressures. Gravity tries to collapse the universe together and pressures push it apart (roughly). When Einstein came up with his model (1915), everyone thought the universe was static (so called "steady state"), ie it didn't change over time. So he included a cosmological constant to counteract the collapsing action of gravity and keep the universe steady. This cosmological constant "pushes outwards" to counter gravities inward push. By 1928 Hubble's catalogue had convinced people the universe was expanding (not steady) and physicists realised the cosmological constant wasn't required. Einstein called its original inclusion "his biggest blunder". It seems that call was wrong. :o)

Now the cosmological constant is coming back. To describe an expanding universe you stick it back in and change the values for the density of normal mass-energy and the cosmological constant, and voila - an expanding universe. The question then becomes: what does this constant physically represent?

At present cosmologists use the term "dark energy" to refer to a number of possible culprits. From the equations we know the properties of this dark energy very well. Some physicists link it to action of the quantum vacuum, some label it "quintessence" (the "fifth force").

It is *not* (as suggested above) dark matter or antimatter. Dark matter is invoked to explain galactic dynamics: galaxies tend to rotate in a fashion which suggests they have more mass than we can actually see. This missing mass is presumed to be dark (which is why we can't see it). Dark matter would act like ordinary matter in Einstein's equaitons, and so can't produce an accelerated expansion. Antimatter also behaves gravitationally like ordinary matter and so it can't be responsible for accelerated expansion either.


Hope this helps!
The Chicken

Answer 2

the way this was explained to me:
imagine the universe as a deflated balloon and draw dots on the baloon for galaxies. When the universe was young (balloon deflated) the galaxies were close together. As the universe expands (inflate the balloon) the distance between the galaxies (dots) increases. There are no dents. The universe is just sort of inflating. Also gravity does not trickle into anywhere. It is a force. If the universe were slowing down its expansion, there would be a point when it would stop. If all matter was not far enough away from each other its own gravitational pull would draw the universe back in on itself. It would implode and eventually we would have a sort of a reverse big bang.

Answer 3

ok right now the universe is expanding and that too with considerable speed which it seems can be explained and proved by the red shift phenomena....the expansion is not exactly speeding up....i.e. it's not accelerating......a.ctually u can imagine three situations here....one where the expansion is accelerating....another where the expansion is constant with time and the third scenario where the expansion is deaccelerating.....now....in all these cases the red shift can be observed as the bodies are still moving apart....the sum total of gravitational pull is may be not enough as of yet....to start the process of contraction right now..or in the near future ..but someday it's going to be...and the universe will definitely converge back into point space....and u may ask as to why this should happen....hmmm.....may be black holes will ultimately produce so much of antimatter so as to converge it back....following the lenz'z law....the effect has to be such so as to oppose the cause and also according to the first law of motion...the initial state of inertia will tend to maintain it's state hmmmmm.......actually i can't really explain it in few lines as to why it will happen...but i can tell that after the universe collapses into a point space...it'll stay there for a while.....and then again the whole process will start off......

Answer 4

Physicists introduce dark matter or antimatter to answer this question. In particle physics, antimatter is matter that is composed of the antiparticles of those that constitute normal matter. If a particle and its antiparticle come into contact with each other, the two annihilate; that is, they may both be converted into other particles with equal energy in accordance with Einstein's equation E = mc2. This gives rise to high-energy photons (gamma rays) or other particle–antiparticle pairs. The resulting particles are endowed with an amount of kinetic energy equal to the difference between the rest mass of the products of the annihilation and the rest mass of the original particle-antiparticle pair, which is often quite large.

Antimatter is not found naturally on Earth, except very briefly and in vanishingly small quantities (as the result of radioactive decay or cosmic rays). This is because antimatter which came to exist on Earth outside the confines of a suitable physics laboratory would almost instantly meet the ordinary matter that Earth is made of, and be annihilated. Antiparticles and some stable antimatter (such as antihydrogen) can be made in minuscule amounts, but not in enough quantity to do more than test a few of its theoretical properties.

There is considerable speculation both in science and science fiction as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely antimatter instead, and what might be possible if antimatter could be harnessed, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the great unsolved problems in physics. Possible processes by which it came about are explored in more detail under baryogenesis.

Answer 5

it really is trouble-free. we are on the middle of the seen universe. each and every of the distant products we may be able to ascertain are uniformly disbursed round us in all instructions receding on an same % as calculated by utilizing their pink shift. The furthest products have the utmost redshift. The seen distance is about 13.7 billion mild years in all instructions, yet because of the redshift the calculated position of those products is extra like 22 billion mild years away. Now being on the middle of the seen universe does no longer advise we are on the middle of all that's or became. yet understanding the position that center is isn't needed to calculate the boom of the universe.

Answer 6

Gravity does not "trickle in" to our universe, it's caused by mass.

The increasing acceleration is caused by "dark energy". What that is exactly, I don't think anyone can really say, because it has never been actually observed.

What's left in the space? New space. Space itself is expanding.

Answer 7

Some physicists believe that there a "dark energy" is responsible for countering the effects of gravity and speeding the expansion.

Answer 8

There is nothing expanding in this universe at all. Whatever you heard is an assumption and perseptions of different people who just want to draw attention towerds them. Universe is here to stay whatever it is and it is the nature which takes up ever new shape and shade to entertain all of us.
universe is like a Sheed in which everything takes shape and looses the shape it is un endingly happening nither it is fast or slow it happens due to nature nature creates all the shapes and shades and creatures in company of the permenant being we could call him God.

Answer 9

It's that there is a route as an option to keep life on earth safe. There is a seriousness that is trying to make itself known obviously.