Recent content by cbd1

Can you expand on that a little? How do we know that spacetime is not contracting within galaxies?

I understand that spacetime is expanding between galaxies, as seen with the cosmological redshift. But, is it also expanding inside galaxies, such as the Milky Way? I'm not sure if the galaxy is gravitationally bound enough to where spacetime might actually be contracting within the galaxy...

Time is separation in space-like points in spacetime. The more separation the space-like points (i.e. the less dense the spacetime), the faster the relative rate of time. (This is seen with gravitational time dilation.) If there is no separation between space-like points--like at a singularity...

But where it gets really tricky is when you try to convert this to general relativity. Is there length contraction in a gravitational field, as there would be in an accelerating reference frame? And, in that case, is the length contraction only in one direction?

Anybody?

Relevant to my last post, does it make sense to imagine that the field equations define/describe the curvature of spacetime around a gravitational body? Say we have a gravitational body of a known mass, e.g. the Earth. Could we say that at a place X distance from the center of the body...

Thanks guys. I'm wondering if I describe in words what GR says about weight, comparing it to Newtonian gravity. The weight of an object = the energy content of that object (it's mass) multiplied by the local spacetime curvature. Would this be incorrect?

Thanks for the reply. Is there something more along the lines of calculating the weight of an object?

Question on calculating gravitation per General Relativity and the field equations: I understand that Einstein's field equations describe spacetime. But I’m not sure of how they are used when evaluating gravitation. For example, the equations describe how spacetime is “curved” by a large...

You mean the quantification of GR requires the invocation of a boson in the classical limit? That is to say that when trying to turn GR into a quantum theory, gravitons would be required.. Or are you getting at something else here?

Thank you. This explanation helps. I am not so sure why I wanted to go along with Newton. Perhaps it was because I do not believe there are gravitons. So, would you say that gravitational waves do not require gravitons? Finally, if the Sun were to suddenly disappear out of the solar system, the...

I understand the theory of gravitational waves. My problem with it is that there is nothing to travel, i.e. no gravitons. So why can't the curvature be directly continuous (as Newton saw it). Like I said, I don't feel it would be in violation of information traveling faster than the speed of...

It is clear from the observed cosmological constant that all of the virtual particles in empty spacetime predicted by quantum mechanics simply cannot exist, or the universe would have swallowed itself from gravity from all of these 'virtual' particles. To me, it is simple, for the observations...

However, Einstein himself was convinced that gravitational waves do not exist in 1936 http://arxiv.org/PS_cache/gr-qc/pdf/9704/9704002v1.pdf If he thought for a second that gravitational waves do not exist, it must not be and integral part to his theory of general relativity. Further we still...

You are exactly on to the fact that general relativity does not give the means of acceleration. It gives the effect of mass-having bodies on spacetime (in mathematical form), and it says that gravity is induced by this "warping," but there is not means by which gravity is actually carried out...