Speed of gravity question

[Obnoxious]

Can someone please explain to me how it was derived that gravitons travel at the speed of light?

[ecoli]

probably because they're probably massless, would have something to do with it.

[Obnoxious]

Explain please

[RyanJ]

Explain please

 

Only objects with zero mass can travel at light speed because of the effect given by [math]E=MC^2[/math] which gives particles something called 'rest' mass, because some of the energy constitutes mass and as you arrpoach light speed more and more energy are needed to propell the object the closer you get. To travel at light speed with any body with lass you'd need an infinate ammount of energy and so would have and infinate mass thus preventing you reaching light speed.

 

There are quite a few recent threads that deal with the speed of light which you cna see a few listed below:

 

http://www.scienceforums.net/forums/showthread.php?t=15591

http://www.scienceforums.net/forums/showthread.php?t=16491

http://www.scienceforums.net/forums/showthread.php?t=16421

http://www.scienceforums.net/forums/showthread.php?t=16509

http://www.scienceforums.net/forums/showthread.php?t=16441

 

I also suggest you lookup some of the concepts in Wikipeda.org - it should help you too understand them!

 

One other thing to note, even a massless particle cannot travel faster than light - you'd need a theoretical particle called a tachyon which most people believe not to exist.

 

Cheers,

 

Ryan Jones

[swansont]

Since gravity waves travel at c in GR, and that theory seems to work pretty well, one might expect any quantum theory of gravity to match that condition.

[Kedas]

Sorry for changing the subject a little but

I was just thinking: is the force of gravity totally immune to time?

 

With other words if an object moved at almost c to or away from a gravity field (other object).

Wouldn't any partical/information exchange be slowed down and therefore decrease the effect(gravity) of the partical/information exchange.

Has this been measured/tested in some experiment ?

This would cancel out any gravity effect of an object if it reaches the speed of c. So a photon could have a mass but for al observers no mass can be detected due to it's speed.

I'm sure I made a mistake somewhere

[mrblond5311]

Sorry for changing the subject a little but

I was just thinking: is the force of gravity totally immune to time?

 

With other words if an object moved at almost c to or away from a gravity field (other object).

Wouldn't any partical/information exchange be slowed down and therefore decrease the effect(gravity) of the partical/information exchange.

Has this been measured/tested in some experiment ?

This would cancel out any gravity effect of an object if it reaches the speed of c. So a photon could have a mass but for al observers no mass can be detected due to it's speed.

I'm sure I made a mistake somewhere

 

 

 

I know that light is affected by gravity. Scientists have been able to view light bending aroung objects in space. such as it appears as though a star is in one place but it's really in another due to the gravity of a nearby object "puling" the light around itself.....or something like that. I'm sure someone else can give you a better explanation but gravity's affect on light has been seen. Of course I could be taking your statement wrong. Reply back. I'm just wondering if this "pulling" of gravity actually changes c?

[Meti]

I may be wrong, just like anyone else; but, I think of there being (what I call) a "sub-space mesh". Imagine grid work in all three dimensions, existing "behind" all that exists. Gravity has a strong effect on this "mesh", as gravity distorts the mesh, so too does anything distort that travels the mesh; but the distortion is more noticeable in light because it is mass-less - easy to guide or alter its path. Whereas with anything with mass, although it is distorted, it is impossible to see or detect this distortion because nothing existing "on" the mesh can actually “see” its effects on anything with mass. The distortion that happens with light is not because gravity pulls on the light, so to speak, but the distortion of the "sub-space mesh" is so extreme (from the light's mass-less p.o.v), that the light simply follows the contours of the distortion of the mesh caused by gravity.

 

If you want me to cite a specific source, I cannot. Just take what I say for what it is and see if it fits your beliefs and opinions.

 

Hope this helps.

 

~Meti

[amrit]

After General Theory of Relativity was published in 1916, Einstein came to the idea that gravitation should be carried by the "gravitational waves" that are in a way similar to the electromagnetic waves - their speed is of "light speed".

 

The "problem" by gravitation is "acting on the distance": how can gravitational force act between two stellar objects ? One answer could be gravitational waves, but in 30 years they have been not discovered yet.

 

According to the "ATPS Theory" gravitation is carried directly by the density of cosmic space. It seems gravitational waves do not exist.

 

see here: "ATPS Theory"

 

yours, amrit:-)