Why is the Universe expanding it gravity attracts?

Question

Why is the Universe expanding IF gravity attracts?

IT SHOULD BE IF

Answer 1

Dark Matter------- or so they believe.

Answer 2

The big bang projected all matter out at nearly the speed of light.  So that's why it expanded for a long time.  But it should've begun retracting by now.  Since it's still expanding at an even faster rate scientists now believe there's something called dark matter that exists in the vacuum of space.  It doesn't interact with light or ordinary matter except for gravity.

And even beyond matter created in the Big Bang, there are quantum particles that flitter in and out of existence that could have gravitational properties pulling the universe apart.

To get off the earth, NASA calculates what's called an 'escape' speed.  It's a measure of the Mass it's rocketing into orbit and the gravity that's pulling it back and tells them how much thrust they need to escape gravity.  When scientists originally looked at the visible universe they said the Big Bang didn't provide enough thrust to escape from the pull of gravity back into a single space.  But with Dark Matter the math works.

Eventually the entire universe will be a cold dark place, unless another Big Bang pushes it back together.

Answer 3

The speed of expansion is appears to be greater than the escape velocity of the universe.  This is the "open universe" scenario.  If there is insufficient matter to "close" the universe due to its gravitation, the universe will continue to expand.  

Dark energy seems to be INCREASING the speed of expansion.  This isn't something anyone expected.  No one knows what Dark Energy is, but observations seem to confirm it.  If the speed of the universe increases past a critical amount sometime in the distant future, the universe could be torn apart in the "BIG RIP".

And thank you for posting an intelligent question.  They are becoming increasingly rare.

Answer 4

first there is no center mass at the center of the universe so there is no gravity pulling the universe pack to the center point of expantion. acording to the big bang theory like any other explosion first there is a force of inercia heading away from the center point of the explosion, then once that force reaches it's climax it will start t withdraw and the force of inercia will be reversed and will suck back to the center point of the explosion. there is no interference with gravity besides that of the masses "galaxies" in motion.

and "Cool dude" because galaxies have their own gravity they will attrack each other not repel.

Answer 5

The energy exerted by the big bang is still greater than the pull by gravity. That is because matter was thrust out at speeds exceeding the speed of light because the laws of physics didn't apply before the universe was created. Even with that, it should have started collapsing in on its self. It is believed to because of dark matter or mysterious matter exert energy enough to tug on the rest of the universe.

As time moves on, the energy after the big bang will get smaller causing the universe to eventually collapse back in on its self.

Answer 6

It is because of a force called Dark Energy (not to be confused with Dark Matter).  This mysterious force does the opposite of gravity, it repels matter.  There is far more dark energy in the universe than there is matter so all the matter in the universe is continuing to fly apart and it is even accelerating.

Answer 7

because the galaxies have their own gravity and they r pushing themselves away and r deflecting off each other.

Answer 8

Why are you able to throw a ball up into the air when gravity should yank it to the ground as soon as it leaves your hand.  Gravity is always pulling the ball down, you just gave it enough kinetic energy to let it have a momentum and velocity away from the ground--for awhile.  If there is enough matter in the universe, including dark matter, it will eventually collapse.  If not, everything will have enough momentum to never fall back towards everything else. Dark energy, which like someone else said, no one truly knows what it is, is repulsive, but dark matter is still affected by gravity and attractive like everything else.

Answer 9

That's the big question.  'Dark energy' is just a code word for 'nobody really knows what's causing this.'  There are a lot of people who would love to know why the expansion of the universe is accelerating instead of being slowed down and reversed by gravity.

Answer 10

The old big bang theory used to claim that there wasn't enough matter in the universe to stop the expansion of special large-scale cosmolgical space but JUST enough to keep mundane small-scale space like planetary orbits and atomic orbitals from increasingly expanding ever more. Not to mention it couldn't explain why the dimensions (another type of space) of the objects didn't expand as well.