Recent content by mijoon

May I add that the Earth would be squished by the tidal forces at around the 8 minute mark.

The gravitational pull is related to the total energy, which includes matter. Converting matter into energy or vice versa would NOT change the gravitational pull in any way. You're thinking that the inertial force associated with rotation would counter the gravitational attaction. However...

In fact, MUCH less than that.

Actually, the opposite occurs. Generally speaking, an astronaut ages more SLOWLY than those of us on Earth. This has nothing to do with being in space, but rather it is because they are moving with respect to us. The same effect is seen in particles accelerated in a physics lab. This effect is...

Here is an interesting discussion of the effect. :smile:

This is only partially true in Newtonian physics and untrue in GR. Firstly, in Newtonian physics, it's not ONLY the mass which determines the strength of the gravitational attraction but also the inverse square of distance to the center of mass. Thus although an object such as the Moon would...

Ange, photons are tiny bits of pure energy. Sometimes they act like waves, and sometimes they act like particles. Yes, they really exist but a complete description can be very complicated.

After approx 5.449 secs of Earth time, the spaceship will be 1 sec. behind. In your thumbnail, Earth time should be on the left of the equation.

Once again I must suggest reading this excellent little paper http://www.mso.anu.edu.au/~charley/papers/DavisLineweaver04.pdf"][/PLAIN] on misconceptions regarding expansion.

According to GR, a clock at the bottom of a tall building ticks more slowly than an identical clock on the top floor. This has been strongly supported by empirical data. If gravity were the result of acceleration, the opposite would be seen.

The Ricci scalar is the contraction of the Ricci tensor which is a contraction of the Riemann tensor. It appears in the Einstein field equations, one of the solutions of which is the Schwartzschild Solution.

Forgive me, but I believe that this is incorrect. See this paper.

I could not explain it better than Space Tiger did. "Flat" does not mean that the universe is shaped like a large disk. "Flat" means that the geometric properties (such as the sum of the angles equaling 180) are Euclidian.

"Flat" refers to its geometric properties not its physical shape.

I must point out that there are very many interesting GR articles on that site as may be seen by http://www.mathpages.com/rr/rrtoc.htm" . :smile: