00:01
This question basically look at the spiral galaxies, right, the distribution of the mass in a galaxy's, right? so sparrow galaxies.
00:18
So it actually was found that the rotation curves of spiral galaxy is a little bit flight, right? you ask it about distribution of the mass.
00:29
You know, there are four options.
00:32
It's very clear that the mass cannot be distributed like.
00:35
In the solar system, right? because in that case, the rotation curve should actually, should actually slow down, right? should actually go down, right? bend down because, you know, you can see that as you go forward from, as you go forward from the center of mass, if the mass is really localized near the center, and then as in the solar system, you know, there's this, there's this, the rotation, the rotation should become slow and slow, right? so it should not be flight.
01:09
So the second is aware, the density remains the same as radius increases.
01:17
Now you see that the force, the first actually, if this is the case, if the mass is really uniform distributed, and you know, you look at a, you look at orbit, and then the force which generally acted on an object on the orbit, you know, is contraband two things.
01:39
First, the distance, which is inversely proportion to a distance, let's say 1 over r squared...