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by dadro 5534 days ago
If it is proven that that anti-matter is repelled by gravity does that mean hover-boards will become a reality in our lifetimes? What are some of the potential practical applications?
2 comments

Given that antimatter explodes violently when put into contact with regular matter, I kind of hope that's not how they go about achieving this. A kid who forgets to recharge his board, allowing the magnetic fields to collapse, could do a considerable amount of damage.
> I kind of hope that's not how they go about achieving this

Don't worry. The design is impractical anyway - regulating the "anti-mass" would be extremely difficult. Just when you got it balanced, the kid would drink a glass of water and the board would sink into the ground.

Due caution would indeed be advisable when selling these gadgets, though. A matter-antimatter collision of 50kg would be equivalent to about 2.1 gigatons of TNT, or about 400 times more powerful than the most powerful hydogen bomb ever developed, so it would indeed caused a "considerable amount of damage".

> The design is impractical anyway

Nah, you just need a miniature collider inside the board, manufacturing more anti-matter as necessary.

And obviously, it would be powered by annihilating matter/antimatter together, via a small Mr. Fusion at the back.

They could just use a compressed-air ballast tank. That would certainly be simpler than a miniature collider, and the explosion risk isn't that bad compared to the rest of the device.
That is a good solution. You should patent it! METHOD FOR DYNAMICALLY REGULATING BALLAST MASS ON ANTI-GRAVITY FLOATATION TRANSPORT DEVICE
So you're saying that this has fantastic military applications? Interesting...
The military don't like antimatter weapons because they are fail-dangerous. They require active stabilisation.

If a nuke fails, nothing happens. If antimatter containment fails, your entire arsenal of antimatter weapons go up at once.

For a similar reason, nitroglycerin is strangely unpopular for both civilian and military purposes.

Interesting, so you are suggesting some sort of gun that creates antimatter in a remote location. That's a great idea!
A weapon that could create antimatter at a remote location would be a particle accelerator. One that could create non-trivial amounts of antimatter would cause far more damage from its direct consequences than from antimatter. By factors of millions or billions.

It would be heinously expensive and would require the kind of energy input that only gigawatt-grade nuclear power plants could provide. Rather than using a complicated, failure prone and inefficient way to transform nuclear fission into destruction, it would be simpler and more effective to lob a nuke with the same amount of uranium or plutonium.

Hence, for your day-to-day megadeath needs, thermonuclear weapons will remain the tool of choice for the foreseeable future.

So .. you don't read much sci-fi, do you?
Not to mention that it would take a LOT of mass to balance out the weight of the board and the person riding it.
Not saying that it's as feasible as normal engine, but when you ride a bike you pretty much fill it with matter that explodes violently when ignited. Then you ignite small parts of it to make the bike move...

We may still see some normal devices which use antimatter in one way or another.

Meaningful amounts of Mater + antimatter produces extreme amounts of radiation, and takes ridiculous amounts of energy to produce.

To put things into perspective, 1kg (~2.2lb) of antimater + 1kg of matter = 2* (9×10^16 J/kg) of energy, TNT = 4.2×10^6 J/kg so that works out to 42,000,000,000 kg of TNT or a 100 mega ton bomb which is larger than the largest H bomb ever tested.

PS: The other issue is unlike gas which is fairly stable, any sort of containment failure = detonation.

No. I am not a physicist, but my understanding is that certain devices that have been proposed for use in space manipulation devices (e.g. wormholes, alcubierre drive), require either a form of matter that has reverse gravity or thousands of times the available energy of the known universe.

http://en.wikipedia.org/wiki/Worm_hole#Traversable_wormholes http://en.wikipedia.org/wiki/Alcubierre_drive

>thousands of times the available energy of the known universe.

the pieces of Universe that is more than 13B light years from us are moving with speed faster than light relative to us. The machinery behind it is space expansion. And by definition that is using energy less or equal to the universe's energy. So that is the start. The Alcubierre drive is the idea of how to use the same principle on much smaller scale. It is very doubtful that it would require more energy than moving the whole galaxies [which, let me repeat, are moving faster than light relative to us and to each other]

Antimatter is not going to help you there. You need exotic matter of the negative mass kind. which are not thought to exist.
>> which are not thought to exist

which have been observed a few times in colliders

Citation needed. Matter with negative mass would be big news.