Gravity, does it have speed?

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sam mower

New Member
Messages
16
Gravity, does it have speed?

I've been wondering...
let me put my question in a form of an example...

The distance between the sun and the earth is roughly 240 000 000 km,
but the accurancy of this information is not really necessary.

The beam of light from sun to earth travels roughly 8 seconds.

So, if sun was to dissapear (not possible, but for the sake of an argument), it would take earhlings 8 seconds to notice that - there would be no more sunlight!

It's exactly these 8 seconds that I'm wondering about... would the earth gone out of orbit around (non existing) sun immediatly, or would it also take 8 seconds, for earth to stray out of orbit.

Is gravity immediate or does gravity travel (if so, propably with the speed of light).


Just corious of your oppinions
ps - sorry for any spelling errors
 

Grayson

Senior Member
Messages
1,079
Re: Gravity, does it have speed?

Pssst, its roughly eight and a half minutes for sunlight to reach the earth.

That doesn't answer your question, just corrects a misconception.:grin:
 

sam mower

New Member
Messages
16
Re: Gravity, does it have speed?

you're right of course :)

but the question remains
 

Grayson

Senior Member
Messages
1,079
Re: Gravity, does it have speed?

Of course it does, I am just not smart enough to answer it. :grin:
 

StarLord

Senior Member
Messages
3,187
Re: Gravity, does it have speed?

"A body in motion tends to stay in motion unless otherwise acted upon some outside force" Thats not exactly word for word but you get the jist. However, The Sun leaves, it stops exerting gravitational forces which cause the earth to stay in it's egg shaped orbit, so from the moment you remove that massive force, the earth goes sailing out into the dark in a straight line untill it is reacted upon by hitting another asteroid or planet. Welcome to midnight billiards.
 

sam mower

New Member
Messages
16
Re: Gravity, does it have speed?

<div class='quotetop'>QUOTE(\"StarLord\")</div>
\"A body in motion tends to stay in motion unless otherwise acted upon some outside force\" Thats not exactly word for word but you get the jist. However, The Sun leaves, it stops exerting gravitational forces which cause the earth to stay in it's egg shaped orbit, so from the moment you remove that massive force, the earth goes sailing out into the dark in a straight line untill it is reacted upon by hitting another asteroid or planet. Welcome to midnight billiards.[/b]


OK, I find it hard to believe, that we're talking about the exact same moment that these effects are taking place...

I'd have to go with gravity traveling by speed of light...
don't really have an argument, guess it has to do with a string theory - string is somehow composed, it's not just created there from scrach.
I dunno, scientists haven't figured this one out yet, but I'm going with speed of light variation.
 

preethi1986

New Member
Messages
11
Re: Gravity, does it have speed?

<div class='quotetop'>QUOTE(\"sam mower\")</div>
OK, I find it hard to believe, that we're talking about the exact same moment that these effects are taking place...

I'd have to go with gravity traveling by speed of light...
don't really have an argument, guess it has to do with a string theory - string is somehow composed, it's not just created there from scrach.
I dunno, scientists haven't figured this one out yet, but I'm going with speed of light variation.[/b]

Eh, excuse me, but gravitational forces do NOT travel. with the sun existing there will be a gravitational field due to the sun. in the presense of this gravitational field, the earth follows its orbit. if the sun was to disappear, so will its gravitational field instantaneously. so earth's reaction to the loss of the sun's gravitational force on it will also be instantaneous.
 

sam mower

New Member
Messages
16
Re: Gravity, does it have speed?

<div class='quotetop'>QUOTE(\"preethi1986\")</div>
Eh, excuse me, but gravitational forces do NOT travel. with the sun existing there will be a gravitational field due to the sun. in the presense of this gravitational field, the earth follows its orbit. if the sun was to disappear, so will its gravitational field instantaneously. so earth's reaction to the loss of the sun's gravitational force on it will also be instantaneous.[/b]

Well then, they don't pack their suitcases and take the highway!
I see it this way: We have point A, gravity beeing there and point B, gravity dissapearing. within point A there's a strong gravity field, as we take this field away influence of it remains and relatively smoothly transforms.

It takes time for a transition to smoothly take place.

Also how can we tell, with extreme gravity effecting time 'n' stuff, my guess would be that it would take quite some time to even it out
 

Cosmo

Senior Member
Messages
2,865
Re: Gravity, does it have speed?

Gravity does not have a speed because it exists as a field of energy if you will. It's not linear like light. Your question can be applied to electro-magnetic fields as well: If I have an electromagnet running, and a small piece of metal stuck to it, how long does the metal stick after I turn off the electo-magnet? It's immediate, like flipping off a light.
 

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