There is no "fabric of space"

[GAHD]

...You cannot generate gravity...

ahem

 

 

Edit:

The force of gravity acts equally on all objects at the same distance. A bulldozer and a thumbtack in the same orbit will travel the same ellipse, despite their difference in mass

they will require different amounts of kinetic energy, and the bulldozer's own gravitational feild will interact with the body it is orbiting, causing said dozer to slip faster than said tack.

[Qfwfq]

ahem, that is a result that remains to be examined.

they will require different amounts of kinetic energy.

I would say they have different kinetic energies and these aren't something needed "to keep them in orbit".

 

and the bulldozer's own gravitational feild will interact with the body it is orbiting,.

The third law of motion isn't overlooked in GR, the force with which the bulldozer attracts Earth is simply the axact same as that with which Earth attracts the bulldozer, it won't cause the dozer to slip faster than the tack.

[ldsoftwaresteve]

Qfwfq:

The third law of motion isn't overlooked in GR, the force with which the bulldozer attracts Earth is simply the axact same as that with which Earth attracts the bulldozer, it won't cause the dozer to slip faster than the tack.

Hmmm. I don't know about that Q. The size ratio of the bulldozer to the tack, if not important, could be extended to something a tad larger. Say the moon? In other words, the ratio of the sizes of the orbiting objects will impact the necessary velocity needed to maintain the orbit.

[Qfwfq]

The size ratio of the bulldozer to the tack, if not important, could be extended to something a tad larger. Say the moon? In other words, the ratio of the sizes of the orbiting objects will impact the necessary velocity needed to maintain the orbit.

Size can mean that the gradient of the field may become important, causing tidal forces, but this influences the motion between the orbiting body's parts. What essentially counts for orbital motion is the centre of mass, the orbiting body can be treated like a particle having this position.

 

Where the mass is anywhere comparable, as in the Earth-Moon case, the proper way to see it is that both bodies are orbiting around their common centre of mass (but not independently, of course). This is conveniently treated by using the position of one body in the other's frame but with the reduced mass, just a trick of algebra really.

[Pyrotex]

ahem

Sorry, but the article says "gravity-equivalent". That's for non-scientific readers. It in no way means or can mean actual gravity.

Edit: they will require different amounts of kinetic energy, and the bulldozer's own gravitational feild will interact with the body it is orbiting, causing said dozer to slip faster than said tack.

I'm sorry, again, but this is just not your day. Bodies in orbit do not "require" kinetic energy, they do not require any energy at all to stay in orbit. They have orbital velocity. True, the kinetic energy of the bulldozer can be computed from its velocity and mass (1/2 mv^2), but it is the velocity that keeps it in orbit. The identical velocity keeps the much smaller tack in the same orbit.

[ldsoftwaresteve]

0.o Well guys, if McCutcheon is correct, then the tangential velocity has to be enough to compensate for the expansion of the objects toward each other. For objects that are negligible in size with respect to the body being 'orbited' all will act as though size isn't important. But, there is a point at which it does make a rather large difference.

there is a case of stars apparently in orbit within what was thought to be the event horizon of a supermassive black hole, but, if memory serves me right, they were really moving quite fast...and, I don't remember there being a comment about their being pulled apart by tidal forces.

[Pyrotex]

0.o Well guys, if McCutcheon is correct, then the tangential velocity has to be enough to compensate for the expansion of the objects toward each other. For objects that are negligible in size with respect to the body being 'orbited' all will act as though size isn't important. But, there is a point at which it does make a rather large difference.....

You are correct. [that's the good news] :)

 

But the size of the orbiting masses only makes a difference in extreme cases. Where the orbit is only a (very) few times bigger than the larger body. Even in the Earth-Moon system, the orbit of the Moon (or the co-orbits of the Earth and Moon around their common center of mass) is sooooooo much bigger than the Earth, that both masses can be considered "point" masses, as Q said in his post.

 

The orbital velocity of a body around, say, the Earth is essentiall a constant for a given altitude. Bigger satellites do NOT have bigger orbital velocities.