[coderdude]

From the article:

"The long term storage of significant amounts of antihydrogen should soon settle the question of whether antimatter falls up or down."

One reason they would like to know if antimatter is repelled by gravity is that it could explain why the Universe is expanding at an accelerating rate.[1]

[1]: http://www.physorg.com/news/2011-04-antimatter-gravity-unive...

[Femur]

>>"The long term storage of significant amounts of antihydrogen should soon settle the question of whether antimatter falls up or down."

Would this mean that if I am "holding onto" a chunk of antimatter heaver than myself I will fall up into space?

[pavel_lishin]

Well, technically, it wouldn't be possible for a chunk of antimatter to be heavier than you.

But yeah, one theory is that if you hold one that's more massive than you are, its repulsion would overpower your attraction, and bang, zoom, straight to the moon!

[hippich]

it should be repelled by moon's gravity back to earth - recursion... =))

[burgerbrain]

https://secure.wikimedia.org/wikipedia/en/wiki/Lagrangian_po...

[StavrosK]

Not unless it's in a tube, and it would quickly reach an equilibrium anyway.

[oewolf]

Unless he starts using his legs for extra propulsion!

[StavrosK]

In a vacuum?

[jwuphysics]

If you were holding onto a chunk of antimatter you would probably be missing a hand.

[swombat]

1 megaton nuke is about 4000 TeraJoules of energy.

10g of antimatter yields about 10^15 Joules - i.e. 1 PetaJoule, or the equivalent of a 2+ Megaton nuke.

If you were holding onto a chunk of antimatter large enough to hold onto you'd be missing half of London.

[Killah911]

Not sure if that conclusion is right. It probably wouldn't result in an explosion and the energy output would probably be in the form of light. Regardless, I'm going with Stephen Hawking on this one: "If you ever meet your anti-self, don't shake hands!"

[burgerbrain]

"It probably wouldn't result in an explosion and the energy output would probably be in the form of light."

That's what nukes do too. Turns out that dumping absurd amounts of light (various parts of the spectrum, but certainly including visible) into the surrounding area absurdly fast tends to fuck stuff up pretty good.

[lutorm]

Yeah, a lot of the power output from a nuclear explosion is in gamma rays, and even air is opaque enough to gamma rays that the energy deposition heats it up to way incandescent temperatures. That's what the fireball of a nuclear explosion is: incandescent air.

[swombat]

Funny that I actually managed to get the maths wrong. 4000 TeraJoules is 4 PetaJoules, i.e. 10g of antimatter is actually a 0.25 Megaton nuke. Still packs some serious punch, but I totally fail at arithmetic, it seems.

[kijinbear]

Not if you're holding onto it using a magnetic field, or any other method that doesn't involve direct contact.

[Cushman]

Is there any conceivable way to make such a system fail-safe?

[Fargren]

Nothing is fail-safe.

[Cushman]

I think you misunderstand what the term means. For example, the control rods in some nuclear reactor designs are held up out of the core by electromagnets. Thus even in the event of complete power failure, the rods fall naturally, stopping the reaction. Since failure results in a safe state, this is referred to as a "fail-safe" system.

By contrast, if you were holding a lump of antimatter contained by an electromagnetic field, a power failure would result is the antimatter escaping confinement and annihilating with your body, releasing an unimaginably large amount of energy nearly instantly. This is what you might call a "fail-deadly" system, because a failure results in a decidedly unsafe state.