"Antigravity"?

[JTM³]

Hi;

 

I was recently something on the science channel about Einstein's life. It talked about the General Theory of Relativity in a way I had never heard before; now, I've seen that program before but I didn't catch that part I guess...

 

It said that Genearl Relativity in effect made the force of gravity an illusion; I have known about the comparison between gravity and a rubber sheet (gravity/spacetime, one of those..) for a long time, but I never knew that gravity is now an illusion; the cause of an object moving through warped spacetime. I might've left something out or said that wrong because I don't recall the exact deatails.

 

So my question is (other than "did I get that summary right?") is, armed with that concept, is it now possible (at least for people far smarter than I ) to work on a device to warp spacetime the other way? Hence, antigravity?

 

However, after thinking on that, we have two possibilities (both could be wrong of course): 1) this way of thinking about gravity opens up new possibiltities for reasearch, 2) Cool to think about, but it doesn't really get us anywhere..."antigravity" particles/fields would have the described effect, rendering my "philosophy" for lack of a better term pointless.......

 

So I was wondering what you guys thought Thanks..

(Not sure if this is the right sub-forum; quantum mechanics or relativity; oh well...)

[[Tycho?]]

Well yeah your summary is pretty much correct. I wouldn't call it an illususion, but you can say gravity isn't so much a field that attracts stuff, but instead something that warps spacetime so that objects travel in a different path.

 

This really is not favorable to antigravity however. If gravity is just a field one can conjur up the idea of anti gravity, just like you can have an electric field and have charges be repelled from it. But if gravity is the result of curved spacetime.... then anti gravity is space time that is negatively curved. And how the hell do you do that? (With "exotic" matter you might say, which just a a different way of saying matter that does stuff that we dont understand).

 

Yeah I'm kinda drunk right now, I hope that made sense.

[Halucigenia]

...........But if gravity is the result of curved spacetime.... then anti gravity is space time that is negatively curved. And how the hell do you do that?

I was under the impression that you could have negatively curved space time.

Is it not still under debate whether the curvature of the entire Universe is positively curved, negatively curved or flat (or has that been resolved)?

[jtzako]

Does "antigravity" necessarily have to push things away? Seems to me creating that effect might be harder than creating a field where gravity has no effect at all. (vs negative-gravity)

[[Tycho?]]

I was under the impression that you could have negatively curved space time.

Is it not still under debate whether the curvature of the entire Universe is positively curved' date=' negatively curved or flat (or has that been resolved)?[/quote']

 

Negative curvature is an idea, but so far nothing else. There is nothing known that could actually cause such a curvature unless it is built into the large scale structure of the universe. And observations have shown the universe to have an almost flat and positive curvature, so it may be a moot point.

[RichF]

This may sound far fetched but how about creating a gravitational force in the opposite direction of the existing gravitational force? Acceleration would be the differance in the two.

[[Tycho?]]

This may sound far fetched but how about creating a gravitational force in the opposite direction of the existing gravitational force? Acceleration would be the differance in the two.

 

Hows about creating a gravitational force that makes delicious pies? Not to sound like like an asshole, but just making up a force that does whatever you want doesn't really make sense in physics. You'd have to explain what causes such a force, how and why it works. So such an idea isn't so much far fetched as... not physics. Suitible for soft sci-fi perhaps.

[RichF]

'']Hows about creating a gravitational force that makes delicious pies? Not to sound like like an asshole, but just making up a force that does whatever you want doesn't really make sense in physics. You'd have to explain what causes such a force, how and why it works. So such an idea isn't so much far fetched as... not physics. Suitible for soft sci-fi perhaps.

 

Not asshole-ish at all. Gravity is a known force/field that causes mass to accelerate. If what ever causes gravitational fields can be discovered and artificially reproduced...there you have it. In 1900 if you asked a scientist if we could explain the energy behind the sun or yet reproduce it 40 some years later they would have said that you are crazy.

 

Far fetched I know but that's just me.

[swansont]

Not asshole-ish at all. Gravity is a known force/field that causes mass to accelerate. If what ever causes gravitational fields can be discovered and artificially reproduced...there you have it.

 

Has any force been "artificially reproduced" ?

[Sisyphus]

My God! All you need to eliminate gravity is a magical anti-gravity machine that creates out of nothing a new fundamental force in large quantities?! Why didn't I think of that?

[Klaynos]

My God! All you need to eliminate gravity is a magical anti-gravity machine that creates out of nothing a new fundamental force in large quantities?! Why didn't I think of that?

 

 

I've got one under my bed...

[RichF]

Has any force been "artificially reproduced" ?

 

Electro-magnetic.

[RichF]

My God! All you need to eliminate gravity is a magical anti-gravity machine that creates out of nothing a new fundamental force in large quantities?! Why didn't I think of that?

 

There is nothing new about gravitational force; matter creates a gravitational field which in turn applies a force on other matter. What causes matter to create the field is the question.

 

Edit: spell monster.

[swansont]

Electro-magnetic.

 

Do you have a specific example of an "artificially reproduced" electromagnetic field?

[[Tycho?]]

Electro-magnetic.

 

But you dont artificially reproduce an electromagnetic field. You just create an electromagetic field, period.

[RichF]

'']But you dont artificially reproduce an electromagnetic field. You just create an electromagetic field, period.

 

Fair enough, I should have used a better choice of words. "Man made fields" would have done better.

[Klaynos]

well in the same way you can get a "man-made" EM field from moving a charge from one place to another, you can move a mass from one place to another to create a "man-made" gravity force... I don't see how this helps?

[Sisyphus]

Ha, so in order to cancel the effects of gravity, all you have to do is keep an equally massive object equidistant in the opposite direction to the local center of gravity. Put a stationary earth-mass black hole 4000 miles above you, and voila! Oh, wait...

[[Tycho?]]

Ha, so in order to cancel the effects of gravity, all you have to do is keep an equally massive object equidistant in the opposite direction to the local center of gravity. Put a stationary earth-mass black hole 4000 miles above you, and voila! Oh, wait...

 

lol yeah, piece of cake.

[trvlrpsmyrph]

There is no such thing as anti-gravity. That's like thinking there is anti-sound or anti-light. The electromagnetic spectrum is always around us, and if it were ever turned off, we (the Universe as we Know it) would no longer exist. If the Earth's temperature were absolute zero, there would be no gravity, we wouldn't need it. As a side note, there is no such thing as perpetual motion either, but we Can utilize (harness, if you will) gravity for our energy needs. We don't need the elements to work for us.

[RichF]

Ha, so in order to cancel the effects of gravity, all you have to do is keep an equally massive object equidistant in the opposite direction to the local center of gravity. Put a stationary earth-mass black hole 4000 miles above you, and voila!

 

That's a very good idea; I'm going to start on that tomorrow!

 

Edit: I should have read this thread first.... http://www.scienceforums.net/forums/showthread.php?t=18462

 

Like I said...I was reaching.