How long will the universe expand before it begins to contract and when it contracts will time be reversed?

Answer 1

Our universe is expanding now, pushed out by the big bang.

Gravity is trying to slow the expansion and pull it all back together.

Which will win? The force from the big bang or gravity? Astronomers have been asking this question for a long time. The answer is stated simply as a number called Omega. They try to measure Omega. If Omega is less than one the universe will expand forever. If it's greater than one the universe will collapse back, as you suggest. If it's exactly one, the universe will expand forever, but the rate of expansion will always be slowing down. After a long while it will almost stop.

Omega is really really hard to measure. It depends on questions like "How much dark matter is there?" The current best value is somewhere around 1/3. But the measurement is so uncertain that could well be one. In fact scientists think that might be the case. They think that if Omega wasn't one we should get an answer like .00006, or 75,000,000. 1/3 is close to one compared to those numbers.

The reason they think that, if it wasn't one, Omega should be far from one, is that the theories of the big bang say that omega was set very early in the bang. And that, unless it was exactly one, it should keep changing over time. They used to be puzzled why it should be anywhere near to one. It was like Omega was balanced on one in a very unlikely way.

Then someone invented a slight modification of the big bang theory called "inflation". One reason people like inflation so much is that it says omega would have been set as exactly one by inflation, where it would stay.

So presently, astronomers think that Omega is exactly one, the universe will expand forever, but that the rate of expansion will always be slowing down.

More detailed information:

http://www.discover.com/issues/apr-02/co...

Answer 2

The universes expansion began to slow down and scientists thought it was going to begin to contract. Then it began to expand again and actually pick up speed. They haven't decided what the explanation is for this. It looks as though our galaxy and all other galaxies will become more and more isolated in the cosmic cloud which apparently preceded the expansion of the galaxies.

This time thing is a carry over from science fiction movies that began to appear in the 50s as a result of abstract writings by well known scientists. Time is not some mystical thing that has a mind of its own and it did not begin on its own at the moment of the theoretical big bang. Time is a yardstick that man has created in order to measure, keep track of, and organize things. We have used units of measuret as technology has advanced. We have counted the number of days it took between full moons, grains of sand, the flow of water, and eventually divided the days into hours, mnutes, seconds, and fractions of seconds. We are now using the speed of light as a unit of measure and we talk about light abstractly as if it is time its self but we calculate the speed of light using seconds and years. When light gets perceptively bent by a strong gravitational force, it means that a direct line between two points has a bend in it and has to be longer between the two points which means that it takes light longer to travel between the two points. It doesn't mean that time has been warped. If the universe begins to contract, we will say things like, "It has been 2 million light years since the universe began to contract" or "the universe began to contract in 2006". Time will not ever run backwards.

Answer 3

Current theory has it that due to there being insufficient mass in our Universe, the Universe will expand forever. Time will or would not be reversed in a collapsing Universe as the laws of physics still remain constant and the collapsing of the Universe would be due to the gravitational fields bringing the matter together which has nothing to do with time/space.

Answer 4

That depends on the overall density of the Universe. It's currently thought that the Universe is 'flat', meaning that it will continue to expand forever, but that the expansion rate will slow down, but never quite stop.
No reason why time should reverse if it's contracting. The Local Group, of which our Galaxy is but one member, is slowly contracting within itself, and time still goes forwards.

Answer 5

We won't know that until we know the value of the Hubble Constant. If it does start to contract, time will not be reversed. And if it contracts, are we headed for a Big Crash symmetric with the Big Bang? Ask your question again in 20 billion years or so.

Answer 6

how did these scientists know that the universe is expanding? is someone at its end edge already? where is the edge and what is it like in there? expanding... expanding to what? if it is called the universe, to what would be it expanding to?
i dont think we should care about these things instead make our our space a little bit better than before we came into it//

Answer 7

the universe will NOT contract because there is too much dark matter to halt gravity
so it will continue to expand forever
after 10 to the power of 100 years (googol) it will be empty space

check out TIME article in July 2001 - excellent.

Answer 8

The "closed" universe, or recycling one the place the it accelerated and decreased in length and accelerated and decreased in length back became as quickly as the extensive-unfold theory. (perchance it incredibly is how the universe breathes. merely kidding!) the main up-tp-date theory is a consistently increasing universe. incredibly, the speed of the undertaking contained in the universe exceeds escape speed. that's going to enhance perpetually. that's good is in all probability no longer likely to be desperate in my lifetime.

Answer 9

by the new information[DARK MATTER} the universe does not contact,it expants for many many yrs.

Answer 10

february 1,2019