• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Gravity is Bunk!!!

Dan, tell us why he paint from your spinning tennis ball winds up on the floor rather than on the walls.
 
If a mass was created instantaneously, would the attractive force act instantly on another body at a distance or would it have to propagate like an EM wave?
 
NeilC said:
If a mass was created instantaneously, would the attractive force act instantly on another body at a distance or would it have to propagate like an EM wave?
Click to expand...

All gravitational influences propagate at the speed of light or slower, but mass/energy cannot be created - that violates the laws of physics (and the equations that tell you about the gravity field). So the question has no answer.

A better question is when the first change in the gravity field surrounding a bomb would occur when the bomb explodes, and the answer is at the same time when light from the explosion arrives at that point.
 
shadron said:
This is the way that I believe describes it the best:

Separate our world, as it travels around the sun, into two parts: the half that is closest to the sun and the half that is farther away. Now, if they were indeed separate pieces, they would be occupying slightly different orbits, one of them having a radius on the order of 1000 miles larger than the other. Kepler's laws of planetary motion (derivable from Newton's law of gravitation) says that the orbit that is larger will take longer to traverse, both because it is a physically longer circumference and because the time required to make an orbit is directly proportional to that orbit's average radius. So, the two parts of Earth would split apart and go their own ways, if gravity between the two parts didn't hold them together. Fortunately it does, but this effect of the two halves tugging against each other is called tidal force, and it actually does cause the liquid at the surface to try to separate on both sides, piling it up to approximately 6' height against what the earth's gravity requires, which is total flatness at a global radius. To a lesser extent, the actual solid material of earth also moves due to tidal forces. The energy required to do that move is converted to heat by friction within the rocks, and is pulled from the rotational energy of the earth's spin. So, tidal forces have the effect of slowing a satellite's spin (until it reaches equality with rotation and the tides freeze in place, and stop dissipating rotational energy).

Whenever a body approaches a gravity well, it will be attracted, and it will essay an orbit of some kind. The two separate halves of the body (in fact, all the parts of the body) will seek separate orbital paths, thus effecting a stretching force on the body. These tidal forces will tear the body apart if the body dives within a calculated radius (called the Roche limit) of the well. If the gravity well is a black hole, it is physically possible to pass much closer to it than the equivalent sun, for instance, because the equivalent massed black hole is much smaller. The closer the body gets to the black hole, the higher the tidal forces are, and they are not ameliorated simply because you may be in circular, or any other shaped, orbit. Matter that actually enters the event horizon has such huge tidal forces acting on it that it is torn into constituent atoms; no information about the structure of the body can survive, according to theory.

Until now. Maybe. http://news.yahoo.com/s/space/20080515/sc_space/newideacouldsolveblackholeinformationmystery
Click to expand...
Minor quibble, the tidal bulge due to the Sun is quite small, the Moon has a much larger effect.
 
wollery said:
Minor quibble, the tidal bulge due to the Sun is quite small, the Moon has a much larger effect.
Click to expand...

Yes, you're right, and neap, and spring, and all that. For the big prize, say why. :)
 
Last edited:
CapelDodger said:
Oh dear ...

Don't assume what we know before you learn it. And you won't learn that magnets stick together because of their energy. They do it because of their magnetism.



Beats being a curiosity.



Oh dear ...

Energy doesn't oppose things, it just is. Forces can be in opposition, and often are, but energy is entirely neutral.

"Energy" is a much-abused word these days. Find out what it really means, scientifically, and you'll be on the road to understanding.
Click to expand...

Im supposed to take physics next semester, hopefully that'll help. I can tell the reason I don't quite grasp it is because I don't know the appro. math/science jargon to even start asking the right questions. I am trying to go too much off of visualizing it in my head.

I'll post another thread about it in the fall I guess:(
 
Just a quick and generally directed Thanks! I appreciate all of you humoring my questions even though it's hard for me to ask the right ones :tongue-ti. Your The Best JREF'ers!
 
As I watched my full coffee cup fall off the table on to the kitchen floor this morning, I (like Sir Issac) had a suddent flash of insight!

Gravity Sucks!

:jaw-dropp:
 
[Gryptype-Thynne voice]
Hello, Neddy. Permit me to demonstrate my new free energy generator- hold this large and heavy magnet...Now step into this conveniently positioned elevator shaft....
(FX- Fading scream).
Good heavens. Three volts. Well done, Ned.
next?
[/G-T]
 
Yes
deformed space also = Expanded space
deformed space also = Twisted space :D.

Mass curves ("deforms") spacetime so that movement along a straight line in spacetime becomes a curve. This curvature in movement is a change in direction of the velocity of an object. This is an acceleration. An acceleration on a mass is described as a force (F=ma). We call that force gravity.
 
Reality Check said:
Yes
deformed space also = Expanded space
deformed space also = Twisted space :D.

Mass curves ("deforms") spacetime so that movement along a straight line in spacetime becomes a curve. This curvature in movement is a change in direction of the velocity of an object. This is an acceleration. An acceleration on a mass is described as a force (F=ma). We call that force gravity.
Click to expand...

This wasn't the question
Could deformed space = Contracted space?
 
You must log in or register to reply here.

Back
Top Bottom