Naked Science Forum
General Science => General Science => Topic started by: sharkeyandgeorge on 11/09/2005 11:13:17
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hello again people this time a sciencey type thought occured and im looking for input is gravity instant? if the sun were to dissapear would earth sail off in a straight line or would it take eight minutes to see the change as the last of the suns light hit us? any ideas or good explanations of whatgravity actually is notwhat it does but how it does it
Giggidy Giggidy Goo
The philosopher Q man
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What a brilliant question !...one would think that it would be eight minutes eh ?...but if the effect was immediate then that would mean that the ' effect ' of gravity moves faster than the speed of light....can't wait to get the answers....,nice one !!
Men are the same as women.... just inside out !!
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Cheers sharkey a question i can anwser, for once i get to be a expert HA!
According to newton the effects of gravity was instantanious but now according to Einstein and general relativity gravity travels at the speed of light.
If you were looking into the sky from earth and saw the sun dissapear, providing it hasn't gone behind a cloud [:)][8D] the loss of gravity would seem to be instantanious,But in reality it would take about eight minutes for the loss of the sun to affect us as gravity travels at c. Proof that gravity travels at the speed of light is the fact that the pull of the sun on the earth come's from where we see the sun now and not from where we will see it in 8 minutes.
Disclaimer
I could be wrong.
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Second the motion, Ukmicky. Einsteins SR also states that information cannot travel faster than the speed of light. If we knew the gravity of the sun had gone poof, but could still see the light from the sun, we would know something about the sun that reached us faster than light speed. - not possible according to relativity.
David
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Hey !!..My presumption was correct too !!
Men are the same as women.... just inside out !!
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Of course that begs the next question, why is gravity constrained by the speed of light? Does it mean that gravity is also carried by massless particles? If so, why can't we build a gravity shade and save ourselves a lot of aviation fuel? [:)]
Please send your answers on a postcard to NSNBT for your chance of a big prize! [;)]
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hehe, good point Simmer. Just have something that blocks out the virtual particles from the earth, and the gravity from the moon will jerk us off planet to die in outer space. Or maybe the sun will get us and we can die from being barbequed.
Seriously, we are trying to explain lots of things with virtual partials. I personally don't buy it as the explanation is just getting too complicated. It seems to me scientists are trying to force things they don't understand into being like things they do understand by inventing these virtual particles. I would rather just say, we don't know how it works, and wait for further light and knowledge on the subject.
David
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Here I go back to my normal not so clever self .I knew it wouldn’t last.[:D]
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So everyone agrees that gravity and light travel at the same speed through the vacuum of space.
But if the two things are restricted too the same speed, that would then mean that either their both made of the same stuff and are both part of the electromagnetic spectrum, which their not.
Or if their not made of the same stuff then the thing that their traveling through "space"must be more than a vacuum and must be made of something that’s interact-able that we can’t see that’s restricting them.
And so as gravity and light are different things restricted to the same speed then that must mean that everything that travels through it has also got too restricted to c.
So Einstein was right as we all knew.
But what is the thing that restricts light, gravity and everything to c.
Is it or could it be what they call dark energy? [:)]
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It is Magic, ukmicky, stuff we still don't understand. We have theories, and they do serve some purpose, but why light speed seems to be restricted, we haven't a clue. That is just the way things are. We can describe it, we can develope equations to describe its behavior, but why or why not is still where the fun is in science.
Right now the way things are, space travel isn't very practical. So if some extra terrestrials do show up they will be using magic (science we don't understand) to do it.
David
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Speaking of magic, antigravity and science I don't understand, have you guys seen this reactionless force motor:
http://www.eureka.findlay.co.uk/eureka_editorial/news_reference/F-Emdrive.htm
and if so, what do you think of the idea; plausible? obvious rubbish?
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Simmer
I tend to side with newton over this one, They also need to test it in a weightless enviroment in order to prove there findings,
As for the article, i would of thought if it was a true and they had invented such a device. such a ground breaking discovery would be plastered over all the scientific magazine's and website's by now.
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Although Gravity travels at the speed of light, is Gravity more localized than light ?...does gravity continue to permeate the cosmos at infinitesimal minute amounts ?
If there is Matter and Anti-Matter, Gravity and Anti-gravity....is there light and Anti-light....or is that what darkness is ?
Men are the same as women.... just inside out !!
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Well, both light and gravity obey the inverse square law so I suppose they both go on pretty much for ever (or until they collide with anti graviton or photons!)
Good point that if the reactionless motor were real it would be huge news - incredibly I've just used a very similar argument in another thread without even thinking of applying the same criteria to this story! [:)]
Just goes to show how different evidence can look when you want to believe something!
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quote:
Originally posted by sharkeyandgeorge
hello again people this time a sciencey type thought occured and im looking for input is gravity instant? if the sun were to dissapear would earth sail off in a straight line or would it take eight minutes to see the change as the last of the suns light hit us? any ideas or good explanations of whatgravity actually is notwhat it does but how it does it
Giggidy Giggidy Goo
The philosopher Q man
This has been discussed at length in (at least) another thread here. The answer is not what you expect. Gravity is instantaneous, but changes in gravity travel at the speed of light. This is because gravity is not a force, but rather it is the shape of space. Just as any mass is, well, right where it is, its gravity is there too. So, the sun has a gravitational field, and we orbit about the center of mass between the earth and the sun. NOT the center of mass where it was 8 minutes ago, but the center of mass where it is NOW. This is esssential to conserve angular momentum. Now if the sun were to disappear, we would wait 8 minutes to find out. That is because gravitons travel at c, and the disappearance of the sun would be propagated at c.
"F = ma, E = mc^2, and you can't push a string."