If gravity travels faster than light, couldn't it be used to send information at superluminal speeds? By measuring gravitational effect, can't you calculate mass of the object and its relative motion?

Yup. But we don't yet have much control over gravity.

I thought it was demonstrated to be the same speed though...

It was published in a non-prestigous journal, was accurate only within 25%, and has already been harshly criticized. According to some experts they mistakenly measured the speed of light instead.

wouldn't GR just fall apart though? I thought it was one of Einstein's most basic assumptions that he had to make.

Yup. very hotly debated right now.

I don't really know any GR.... what would the impact be if it was superluminal?

Yup. But we don't yet have much control over gravity.

 

Well, the point wasn't really that someday we could harness this potential...

 

I thought information at >c speeds was a big no no..

R_{:alpha::beta:}-(1/2)g_{:alpha::beta:}R+:lambda:g_{:alpha::beta:} = ((8:pi::kappa: )/c²)*T_{:alpha::beta:}

 

(Einstein's field equation)

 

Look that over, I'll explain more later, late for class

 

also need to get a better symbol set, any ideas where?

field equations? oh I'll have two, no fries.

Sure no problem, looking it over now.

 

Well first of all, consider the constants in the expression:

 

:kappa: is the gravitational constant; 6.67259x10⁻¹¹m³kg^-1s⁻²

 

:alpha: is the fine structure constant, ~7.2993x10^-3

 

:pi: of course is 3.14159...

 

and c is (currently) 2.99792458x10⁸ m/s

 

 

 

I'll let you all work on it for a while now.

is the gravitational constant; 6.67259x10−11m3kg-1s−2

 

I thought that was Boltzmann's constant (they look so much alike). How do you tell them apart? I've seen B's constant written that way too.

boltzman's constant wouldn't be abbreviated with a g...

Originally posted by fafalone

also need to get a better symbol set, any ideas where?

 

you could make a load of vbcode tags for MathML i suppose. although you need mozilla or a special plugin for IE, it does make symbols (and indeed the math) look nice

I think gravity could be the result of faster than light forces. Read "The circulating Universe, A new Dynamic"

on this forum..

That of which gravity is the result is not known. There are several theories. The most obvious is that gravity is an attribute of the elemental particles. That theory is out of favor because it involves action at a distance and explanation by definition. Under that theory gravity is eternal as is its host particle. If the particle moves so does its gravity, instantaneously.

gravity is effectively affected as mass comes "into being"...apply a "bias" somewhere, and "SEE" how gravity "acts", ( being a "Weak" force, gravity is easily manipulated). ... When worlds are formed, bais are applied and Gravity , having allready been there, (for gravity is infinitely "faster" than light) "gives way to mass". ...(mass affects and effects gravity). Where a bias is applied, gravity is manipulated...

gravity is effectively affected as mass comes "into being"...apply a "bias" somewhere, and "SEE" how gravity "acts", ( being a "Weak" force, gravity is easily manipulated). ... When worlds are formed, bais are applied and Gravity , having allready been there, (for gravity is infinitely "faster" than light) "gives way to mass". ...(mass affects and effects gravity). Where a bias is applied, gravity is manipulated...

 

 

There is another "thread" on this, where it is "explained" that gravity is not "faster" than light. Plus, you need to "define" your terms to have them "make sense."

What was wrong with typing [math]R_{\alpha \beta}-\frac{1}{2}g_{\alpha \beta}R+\lambda g_{\alpha \beta} = \frac{8 \pi \kappa}{c^2} T_{\alpha \beta}[/math]?

Hasn't there been more than one experiment to determine that gravity does indeed seem to propegate at c? One was observing the collapse of a binary neutron star system, I dont remember what the other one was.

What was wrong with typing [math]R_{\alpha \beta}-\frac{1}{2}g_{\alpha \beta}R+\lambda g_{\alpha \beta} = \frac{8 \pi \kappa}{c^2} T_{\alpha \beta}[/math']?

we didn't have [math]\LaTeX[/math] at the point, i think.

'']Hasn't there been more than one experiment to determine that gravity does indeed seem to propegate at c? One was observing the collapse of a binary neutron star system, I dont remember what the other one was.

 

Yes, mentioned in the other thread(s) about the subject.

I thought that massless particles could move at, but not above the speed of light, and gravitons (if they do exist), could move at the speed of light, but not fasted.

Rosemary:

 

You are correct assuming that gravitons have a rest mass of 0. This is a fairly safe assumption, if gravitons exist they must have specific properties, a rest mass of 0 is one of these properties.

 

So yes, your "thought" was correct.