The fact that light has no mass but is effected by gravity is contradicting what I believe about time not being physical...
It is odd how light should have no mass, yet it can have momentum.

This post was edited by L4d on Oct 19 2011 07:23am

Whether it makes sense or not doesn't matter. They use the principle of time dilation in the CPUs that go into our satellites. They're traveling fast in enough that if they didn't factor in time dilation then their clocks would run too slow (since they're moving relative to us) and it would throw off our worldwide communication system.

There are also radioactive particles called Muons which have a half-life that is so short that one entering our atmosphere would decay before it ever reached the ground. However, because they move so fast, time for them is slower, so that allows them to reach detectors on Earth. That's further proof of time dilation.

So, if time has physical properties, "warp speed" could be possible by the stretching or contracting of space-time, no?
But, this would cause g-force for any mass, so humans being able to move at "warp speed" like Star Trek is ridiculous!
But, Futurama's spaceship could work, because it somehow could move space, and, therefore, its passengers would be still, experiencing no g-force.

This post was edited by L4d on Oct 19 2011 07:54am

Because gravity and light travel at the same speed, it cannot be the immense pull of a black hole that makes light unable to escape it, so I am going with the OP that it is because of how space-time is curved that light cannot escape it.

This post was edited by L4d on Oct 19 2011 08:22am

I must admit that I was wrong, as there is conclusive evidence of time dilation.
So, do space shuttles have to compensate for time dilation, too, since they travel so fast?

ok
einstiens original "thought experiment " , was of a room , in space , with a rope attached to the roof
if theres some" being " , that pulls on the rope , with constant force , what would a person inside that room observe ?
he would assume that there was a gravitational field ( as the floor is being pulled up at a constant speed )

this sets the stage for the equivalence of a gravitational field ,and acceleration
so , simply imagine this
the " space " is being accelerated into the black hole
in order for the light to escape , it must move away from the black hole faster then the space it sits in is moving towards the black hole

its like you are on a conveyor belt , and there is a post next to it
if you want to stay level with the post , u must walk ( or run ) along the conveyor belt , at the same speed it is moving
if u want to move past the post , u must run faster than the conveyor belt

a black hole causes the conveyor belt to move faster than light moves

This post was edited by Matao on Oct 19 2011 11:22am

Are you sure that gravity is causing light to speed up towards the black hole, or is it that the black hole has bent space-time in such a way that light gets trapped because of the path that light then has to take?
Gravity and light travel at the same speeds.

This post was edited by L4d on Oct 19 2011 03:43pm

the light is inside the event horizon to begin with






Thats not really true though; black holes work by bending space time so that all possible paths lead back to the center of the black hole



yea thats my understanding of it. So how come people define black holes as an object with an escape velocity greater than c?

for example, http://en.wikipedia.org/wiki/Escape_velocity#Gravity_well scroll to the bottom and under "see also" they define black holes that way

or for a more indepth description: http://en.wikipedia.org/wiki/Schwarzschild_radius

and they use the schwarzschild radius equation to calculate the radi of black holes, which is based off the definition that black holes have an escape velocity >/= c

but i dont see how escape velocity is even relavent since you could go infinitely fast and just loop back to the center of the black hole

Saying that the escape velocity is greater than the speed of light just means that nothing can ever escape it. It's not perfect, but it's not bad for a one-line definition.

The Schwarzchild radius is the "point of no return", meaning if light (or anything else, of course) passes within that radius it can never escape. You're correct in thinking that escape velocity is no longer relevant inside that radius since space itself contorts such that escape is impossible.

Of course, if one could find a way to travel to a fourth spatial dimension that was NOT curved as much as the three spatial dimensions that we experience regularly, then you could potentially escape. However, that's hypothetical at best and extremely unlikely.

I will answer my own question, because I did some research that states that light is effected by gravity, so gravity will cause light to speed up towards the object that is causing gravity to pull light towards it, but the fact that space-time is contorted in such a way via black holes makes it that more difficult to escape this "trap".
I suppose if something was faster than the speed of light, that could escape the pull of a black hole, but it would have to, also, escape the contorted space-time.

This post was edited by L4d on Oct 20 2011 11:11pm