Tuesday, December 02, 2008

What if... #2

Today's thought experiment:

What if we could create anti-gravitating matter?



This post is part of the 2008 advent series "What if..."

35 comments:

Daniel de França MTd2 said...

Spacesips would be submarines and blackholes, perfect distillers.

I'd create a balloon with anti gravitational matter, tied with a rope to the floor. This way, one would be able to fly to outer space easily, and the counter weight would be the rope itself. So, the height would be controled just adding anti grav gas.
So, spaceships would be like submarines, where anti grav is air inside the submarine, and grav the water counter wait.

Also, the even horizon of black holes would be perfect distillers for grav/anti grav combinations. Only the matter part would enter it, the anti grav would be totaly repelled.

Peter Turney said...

See H.G. Wells, The First Men in the Moon, published in 1901, made into a movie twice, in 1919 and 1964.

Rae Ann said...

It would most likely be turned into some kind of cosmetic surgery treatment, like Botox. ;-)

Bee said...

*lol* I thought moving companies would go bankrupt. Just buy a block of ag matter, tie it to your couch and give it a kick.

0FfeS said...

But where could this ag matter be found?

In ag matter factories, of course, and all thanks to the discovery of higgs boson.. XD

B.C. said...

Careful, Bee. Unless you have also removed the inertia from the couch, you are likely to hurt your foot kicking it.

Uncle Al said...

What couples inertial and gravitational mass in invariant ratio? Dry marker bad, lab bench good.

1) Do Casimir etalons violate the EP? Horizonally spin a flat silicon torus over alternating vacuum sputter deposition zones. 70 nm of pure aluminum then 37 nm of 60:40 MgF2:LiF. Matched CTEs; RI = 1.628 a at 121 nm (lambda/2 optical thickness). Round and round to build a bifilar spiral 37 wt-% Casimir etalons. Cut a piece and free the support. Eötvös experiment!

2) Do metaphoric left and right shoes fall differently? A parity Eötvös experiment (pdf) is easy to perform. Divergence will birth more capable theory to amplify the effect.

Anonymous said...

I think you need to be more specific. Is this negative matter? Or some kind of positive matter that happens to warp spacetime in the opposite way as normal matter?

Actually, regardless, my guess is: It explodes.

Bee said...

Hi Anonymous,

Well, the idea was to let the specific details up to you. What do you mean with 'negative matter'. Why should it explode? Best,

B.

Bee said...

I think it would be cool to have rooms where people live on the ceiling by putting layers of anti-gravitational matter on the floor. One would need some kind of double-door to turn around though or one falls up and breaks ones neck. Best,

B.

Bee said...

Hi BC,

Well, the question is what is the ratio of gravitational to inertial mass then? I would think the simplest case is to just flip its sign. However, as far as I am concerned the trouble with moving furniture is vertically, not horizontally. If you have a wooden floor e.g. you can pull things around on a carpet, works pretty well (just that then you have the problem furniture might move around even if you don't want it to.)

I would guess that traffic would become 3-dimensional. We'd need a lot more traffic regulations. And airports would become a lot smaller since you don't need long runways anymore to take off.

Best,

B.

nickoneill said...

Maybe we already have. Presumably you'd need a LOT of it to overcome the force of regular gravity.

Tkk said...

It has already been done. It is called the United States budget and overall economic finances. It was created according to the Wall Street Anti-Uncertainty Principle where economic anti-energy of any amount can be made to appear for a certain period of time without consuming regular energy. This anti-energy is a form of anti-gravity, which can temporarily the weight of a whole country to Cloud 10.

Phil Warnell said...

I was just wondering if Aunty Gravity was related to Mother Nature? :-)

andy.s said...

Enough of this layman's babble. If you're going to talk science, you need to use proper scientific terminology.

The correct word for this substance is Upsydaisium.

matt b said...

Do you mean that the matter would ignore the gravity force or that the sign would flip?

Mr. Hyde said...

Put a ton of normal matter next to -1 ton of anti-gravitating matter.

If Newtonian approximation still manages to stay correct, then gravitating matter will be repelled, anti-gravitating matter will be attracted. The pair will accelerate and fly away at high speed. Warp drive!

Anonymous said...

Bee -

I meant by negative matter, that its mass is a negative number.

In which case, I suppose that its mass is either real, so it annihilates with normal matter, or it is complex, in which case it becomes tachyonic. My suspicion is that if matter could in the real world become tachyonic, that it would immediately bang into some other particle and release lots of energy - but that's just a guess.

At a minimum, its difficult to see how anything larger than a particle could be made with negative mass, since the effect of the strong and electromagnetic forces would also reverse and then how do you make atoms? So it explodes at the level of composite matter even if the particles don't annihilate or explode on their own.

The other way matter could be anti-gravitational, I suppose, is if it had positive mass but emitted anti-gravitons i.e., warped spacetime in the opposite way from normal matter. In this case, the other forces wouldn't necessarily reverse, so you could make an atom, etc. But this would really give you hovering or anything. A small amount of the substance would appear to weigh less within earth's gravity well than one would expect based on its mass. Unless the mass were large enough to be repulsive with the earth -- wouldn't that mean it would have to weigh more than the earth?

So how did I do? Completely naive or is there hope for me?

Bee said...

Hi Anonymous:

I meant by negative matter, that its mass is a negative number.

In which case, I suppose that its mass is either real, so it annihilates with normal matter, or it is complex, in which case it becomes tachyonic. My suspicion is that if matter could in the real world become tachyonic, that it would immediately bang into some other particle and release lots of energy - but that's just a guess.


Well, it is either negative or complex, but not both. I was thinking of negative gravitational mass. Best,

B.

Bee said...

Hi Mr Hyde:

Put a ton of normal matter next to -1 ton of anti-gravitating matter.

If Newtonian approximation still manages to stay correct, then gravitating matter will be repelled, anti-gravitating matter will be attracted. The pair will accelerate and fly away at high speed. Warp drive!


They will be mutually repelled. You have implicitly assumed that the equivalence principle remains valid, which I do not think is consistent with the existence of anti-graviating matter. Best,

B.

Anonymous said...

Well, it is either negative or complex, but not both. I was thinking of negative gravitational mass.

I've always thought of complex numbers as negative, or at least as acting like negative numbers in the sense we're speaking about. Maybe that's not right.

How'd I do otherwise -- if the mass is negative (but not complex), then it either (a) annihilates with normal matter, or (b) explodes because the other forces are reversed?

Anonymous said...

If I'm mistaken that complex numbers act like negative numbers here, then how would you calculate the effect of a force on tachyonic matter? I mean, would a normally attractive force attract or repel a tachyon?

Bee said...

Hi Anonymous:

Well. A complex number is not (generally) a negative number. The complex numbers cover a plane, the real numbers are one axis of it. The tachyonic mass you were referring to however is purely complex - which is the axis orthogonal to the real axis. It does not lie on the real axis, thus saying it is negative does not make sense.

Weather or not negative and positive gravitational mass can annihilate depends on whether this interaction is allowed. Also, you seem to assume that gravitational mass is the same as inertial mass, whereas I was assuming the inertial mass of both remains positive (generalize to energy instead of mass for GR). In this case you can not annihilate a pair since you'd have to destroy kinetic energy into nothing.

Regarding the question how tachyons gravitate. I would say as long as the equivalence principle is valid the mass doesn't matter for the equation of motion.

Best,

B.

Plato said...

If you "wrap the matter" and are able to flip the switch, it would have caused one to wonder about the ability of "choice," in that matter?

Given the "exact location" of this choice we would have to be most certainly aware of the "escape velocity of the photon{it's gravitational potential energy is}" and work backwards in term of the "mass allocations" and "it's derivatives there of?" "ON the planet," and in various spots?

You'd have to know how to "control it." Of course this is based on the "What if #2.....:) While Grace can figure out these "density variations" I would like to think the "elemental nature" would play a part as well, as we would want to adjust using this feature according to that location. It would have to be a very "fluid thing" in travelling

This is all fictional of course, and at times, totally incoherent I know.:)But maybe it can be corrected scientifically while in this fictional state.

Best,

Anonymous said...

Regarding the question how tachyons gravitate. I would say as long as the equivalence principle is valid the mass doesn't matter for the equation of motion.

Thank you for educating me. Maybe I'm just being dense, and I'm sorry for pushing you about it but I do feel like I'm learning something here, so I hope you'll bear with me.

The gravitational force between two masses (using classical theory, to keep things where I feel more comfortable), it seems to me, can either pull, or push (if there is such a thing as negative gravitational mass). But if one of the masses is tachyonic, the force is complex ( real mass * complex mass over real distance squared times times real gravitational constant = complex number ). So is the mass pushed or pulled?

How does the equivalence principle solve this problem?

Maybe this is the danger of thinking about hypothetical particles in classical terms? But there must be an answer of some kind.

I appreciate your comments.

Klaus said...

recomended:
http://www.youtube.com/watch?v=P5_Msrdg3Hk

best
Klaus

Bee said...

Hi Anonymous,

I was thinking of test-particle motion in a background field, not the particle itself causing a curvature. If you'd just couple the tachyon as other fields I guess the metric would have to become complex. Though mathematically this isn't a problem, I don't know what sense this makes physically. (Also, please note I didn't say the EP should hold, but just speaking of the case when it remains valid.) Best,

B.

ck said...

Can we create anti-gravitating matter? Actually nonlinear electromagnetism due to
very strong electronmagnetic fields might
have the effect of antigravity, see . arXiv:0811.4467.

Phil Warnell said...

Hi Bee,

If what is being thought as being antigravitational matter is matter upon which the effects of gravity as being neutral it would appear to me as being difficult to keep it in one place, let alone hover. What I mean is within our solar system or within the galaxy there is also inertia to consider. So for such matter not being affected by gravity it cannot be assumed that it is also non inertial. So in the absence of gravity would not such matter defer (default) to its straight line path which would in itself create an acceleration of sorts relative to normal matter?

Best,

Phil

Bee said...

Hi Matt:

Do you mean that the matter would ignore the gravity force or that the sign would flip?

I meant (roughly) that the sign would flip. It would seem then though you could tie both kinds of matter together and get something that doesn't gravitate at all. Best,

B.

Bee said...

Hi Phil,

Sorry, I don't understand what you are saying. If there was no gravity, both kinds of matter would just be indistinguishable, i.e. move with constant velocity. I never thought of anti-gravitational matter as 'not gravitating'. I am not even sure exactly what that means, since it would necessitate that this kind of matter does not couple at all to the field equations, which means it can not carry any energy or momentum, which means it basically doesn't exist. The thing is that generically all fields couple to the background, thus all of them gravitate. I was just trying to speculate, what if not all of them gravitate similarly. Best,

B.

Phil Warnell said...

Hi Bee,

“I am not even sure exactly what that means, since it would necessitate that this kind of matter does not couple at all to the field equations, which means it can not carry any energy or momentum, which means it basically doesn't exist”

This in effect has answered my question, I believe??? What I simply meant is what gives an orbiting mass a circular path around the sun for instance, is the path is formed by the resultant combined effects of both gravity and inertial motion (Newton). With GR its curved space-time which means that here such matter would recognize no such curvature (for lack of a better term). Therefore only straight line paths would be expected.

Bottom line here is I don't think the movers have much to worry about:-)

Best,

Phil

Bee said...

Hi Phil,

I think I roughly understand your question, and though I am sorry for saying it, I think you have some misunderstanding of General Relativity. The curve on which the mass is orbiting *is* the straightest path. It is the straightest path in a curved background, there is a generalization of 'straight' for curved spaces which is called a 'geodesic'. The geodesic curve on which particles move in general relativity has nothing to do with the inertial mass of the particle (it doesn't appear in the equation). In the case where it is a testparticle, the mass doesn't matter at all, in the case the gravitational field of the mass itself is relevant it's its graviational mass that matters, not the inertial one. The reasoning you have given is for Newtonian gravity, but it doesn't translate into GR. The whole curve of the mass is just due to gravity, and nothing else. Best,

B.

Phil Warnell said...
This comment has been removed by the author.
Phil Warnell said...

Hi Bee,

Yes what I was referring to begin with was matter that was somehow neutral to gravity's effect(not counter), where spacetime curvature (it's geodesic)would be in some unexplained way just not recognized, which in itself makes no sense to me either (as you so insisted and apltly explained)in the first place when it relates to GR. In the Newtonian perspective it can be described to have some sense if only in the context of imaging its nature.

I understand that the path taken is the straight one as defined and mandated by spacetime, which in turn has been so affected by the presence, quantity/density of mass/energy. I’m still puzzled however by how that would be affected (shape as to path) by what is imagined as antigravitational matter. For as it has been simple put (perhaps too simply), matter/energy informs spacetime what shape it should be, while in turn this shape dictates how it (matter/energy) can travel.

With what is imagined as antigravatational matter what shape would it tell spacetime to assume in respect and relative to the path as taken in the presence of that of normal matter? Another way to express it would be in the regular sense, normal matter is not attracted to other normal matter (as Newton so imagined), yet rather spacetime is (in a very loose sense) disturbed by the matter/energy as to have it’s concentration increase proportional to the closeness and density of the matter/energy by which it’s affected.

It would seem that in the case of antigravitatonal matter this would be reversed, where the concentration of spacetime would proportionally increase (again very loosely expressed) as the distance from this form of matter/energy becomes greater.

Just as a final remark I also realize that inertial paths taken cannot possibly be different, for the straight path is always straight path, as so defined and allowed for by GR. Yet with what I initially conceived as what was meant as being antigravitational matter serves for me to further emphasis that GR is much different, not just merely conceptually, yet in the more practical sense then the Newtonian perspective.


Best,

Phil