A question about the famous bucket experiment Suppose that we have a bucket containing two liquids with different densities.Suppose also that i connect the bucket with an electric motor and i rotate the bucket.


*

*Why when the bucket rotates, the heavier liquid is pushed to the outer periphery?

*Have i contrived a machine that produces gravity? This is the impression that i have after a google research. Could someone give an intuitive explanation about how is gravity involved?
EDIT
What is pulling the liquid outside? Is it the all the astronomical matter as Mach wrote? How is it attracted to the walls of the bucket?
EDIT NO2
Although the question is tagged newtonian mechanics i think it rather belongs, as the answers suggest, to general relativity. I would really appreciate an intuitive or not answer at the context of general relativity
 A: 
What is pulling the liquid outside?

Nothing.
What is happening is that the bucket is pulling the liquid inwards towards its centre of rotation. This means the liquid does not continue travelling in a straight line, which it would do in the absence of any force acting on it.


Have I invented artificial gravity?

Not really.
Einstein observed that the water in the bucket is unable to distinguish between the two situations


*

*It is sitting in a bucket on a planet whose gravity pulls the water towards the base of the bucket.

*It is sitting in a bucket that is a non-inertial reference frame, i.e. is being accellerated (in this example by a centripetal force).
A: 1) As the bucket spins, frictional forces will gradually spin up the liquids until their rotational rate matches the bucket. Let's say that the radius of the bucket is R, and the rotational rate of the bucket is $\omega $ Then, for liquid near the wall of the bucket, a small volume of the liquid with mass M will feel an apparent radial force outward of $$F =M \frac{\omega ^2}{R} $$ This is simply centrifugal force, and there is no need to go into questions of whether it's a "real" force or not.
So, for two liquids with different densities (that is, the liquids have different densities, which is not necessarily the same as your statement the one liquid is heavier than the other), the denser liquid will be driven outward harder than the lighter liquid, and this will cause the denser liquid to migrate outward. To switch gears a bit, it's the same reason a dense object sinks in water. The dense object is pulled down by gravity more than the volume of water which it displaces.
2) Have you invented a gravity machine? Well, yes and no. No in the sense that you have not actually produced gravity, which acts on an object regardless of its motion.
But yes in the sense that you have found a way to produce a force which behaves very much like gravity AS LONG AS THE MOTION OF THE BODIES INVOLVED ARE FORCED TO MOVE IN A CERTAIN WAY. Actually, what you've "invented" is a centrifuge. These are widely used in medicine to separate blood and other liquids into their component parts for analysis. On a large scale, like hundreds of feet across, such a device could be used to provide "artificial gravity" for people in space. A large enough centrifuge spinning fast enough (but not fast enough for the inner ear to detect the rotation and make folks dizzy and maybe seasick) could provide an environment in space which would prevent the bad effects of zero-g.
EDIT - With the addition of the question, 

"What is pulling the liquid outside? Is it the all the astronomical
matter as Mach wrote? How is it attracted to the walls of the bucket?" 

I'll expand my answer. You are, I think, referring to Lewin's online lecture Circular Motion, Centrifugal Forces, Perceived Gravity  and he specifically discusses your question at about 17 minutes into the lecture. At about 22:30, he talks about "creating artificial gravity". But he then discusses the situation ALWAYS in terms of "what do you feel", rather than "what is the direction of gravity", and you need to pay attention to the difference. He then talks about centrifuges at about 35 minutes in. His explanation is clearer than I can hope for, but I'll try to rephrase it. 
Consider an atom at the end of a string, which is being spun around a central point. At some time, cut the string. What will happen to the atom? It will fly off in a straight line which is perpendicular to the string at the moment it was cut. So that is how an atom (or any mass) in the absence of an external force. "Things in motion tend to stay in motion." Now think about the atom when the string is not cut. In order to remain in circular motion, a force along the line of the string must be constantly applied. If it weren't, the atom would move in a straight line, not a circle. It is this force which you are referring to as an attraction, and it isn't.
Please watch the lecture again, and pay attention to the fact that he is talking about perceived gravity.
