quote:
Originally posted by apache:
Now, as for DMM, if you have read some of my other Posts lately, you would know that I am not going to take a theory lying down.
First of all, there is the massively disputing theory of general relativity, which essentially throws Newtonian theories out the window. I'm not gonna argue anything about it, though, since I have a limited understanding, and its all theory anyways.
Second, anything regarding the gravitational forces at the center of a massive object is completely theoretical, and there is absolutely no experimental proof to support any of it. Therefore, taking it as a fact is something best done with a grain of salt, rather, an entire salt shaker.
General Relativity doesn't dispute Newtonian physics, it encompasses them. Newtonian physics works, as we see proven every day with our satellites, rockets, and planetary astronimcal observations. The term "theory" here does not mean "completely unproven" - newtonian and GR physics have been borne out in countless scientific experiments. To say "it's all theory anyway" implies it is all completely untested and anybody's guess, which is totally untrue.
You can say we can't be sure about the gravity at the center of a planet just because we haven't measured it directly, but the world uses the math of physics to predict behavior/properties of things reliably, all the time.
quote:
Third, getting a net zero gravitational force is vectorial and mathematically correct, but the fact is that the gravitational forces could not cancel each other, putting no force on the body, they just act to keep the object at the center of the body in equilibrium, or in otherwords, they will not induce a velocity or accleration on the body as a whole in any direction.
However, if the object at the center could not withstand the forces pulling on it, it would indeed be ripped appart. Think of it like a reverse pressure. Rather than keeping an object from expanding, like air pressure acting on a balloon, it would keep an object from imploding.
Hmmm. I'd say that if the net gravitational force on an object is zero, that by definition, all the gravitational forces have canceled out. Gravity is not like pressure in the example you give. For a small object (relative to the size of the planet), say a person, if the net gravity is zero for that person, every point (ie: every cell, every molecule) on/in the person will have a net gravity of zero. The tidal differences between, say, points on the person's left and right arms would be too small to matter.