Why does the outer levels of the galaxy move faster than the law of gravity?

Question

How come that the outermost part of our galaxy move at a faster speed than the law of gravity.

Well, let me ask it again in a different way, my brother says that in between galaxies there is a space, and this space is dark matter, is it true?

Answer 1

Just a quick question...what is the law of gravity? And what speed do you refer to? What is the genesis of this question?

We can talk light speed.

We can talk dark matter.

We can't talk the speed of the law of gravity.

Answer 2

Lets take it slow.

There are galaxies (like ours and billions of others). Some are clustered together relatively closely, bound in a "herd" by mutual gravitation.
Outside these clusters is a lot of space that has very little matter in it compared to within galaxies.

But scientists have analyzed gravity waves and other electromagnetic radiation from within these clusters and between them, and have found that there is another form of matter (they call it "dark matter") that appears to affect the gravity fields in and around galaxies and clusters.
The theory right now is that dark matter and normal matter were mixed up fairly evenly just after the Big Bang. But as normal matter cooled and started to form stars and galaxies, dark matter didn't cool and therefore didn't condense into smaller more dense objects. It just stayed there.

So galaxies and clusters of galaxies all seem to be embedded in "halos" of dark matter that affect the gravity in and between the galaxies.
Its this dark matter halo that causes the stars in the outer edge of our galaxy to orbit the galactic centre much faster than they would if the only matter in a galaxy was what we can see.

Answer 3

You are talking about the fact that the outer portions of many galaxies and globular clusters rotate faster than would be expected and that the gravitational pull of the galaxy or cluster is not enough to prevent the stars from being flung out, so what is keeping them in?

Well the answer may very well be dark matter. The problem is, we can't observe dark matter directly.

Answer 4

They are calling it "dark matter" That way they can say it is still normal gravity. Gravity from matter that they can't see in stars or dust clouds that are visible in telescopes. It might be normal stuff, like lots of planets wandering between the stars where we don't notice them, or it could be some exotic new kind of matter. Nobody has a clue. They are all guessing. The first one to prove his guess correct with actual observations will win a Nobel prize.

Answer 5

space and dark matter are different. space is the actual space that things fit into. and yes theoretically the space between galaxies, stars, probably planets, and maybe even the space between you an your computer, is filled with dark matter.

we havent been able to prove the existence of dark matter because it doesnt interact with anything besides with gravity. so we cant see it o anything. we just think its there because we can see its gravitational affects on everything else.

Answer 6

What are you talking about? Do you know what you're talking about? this question makes no sense.