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Comment by andrekandre | Hacker News Reader

  In any case, both UK and Chinese scientific teams are not on the verge of a machine that can create everyday objects from a sudden blast of laser energy — so far, that reality only exists in science fiction.

assuming 100% effeciency, it would still take 1kg of matter converted to some kind of energy (power generation) to light to get that 1kg back again in a different form... is that correct?

and i guess if you wanted to get anti-matter... would this be more efficient way thanother current methods?

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Given current knowledge of physics, 1kg of energy would create .5 kg of matter and .5 kg of antimatter. The apparatus would need to immediately separate the two to prevent an extremely large explosion.

Presumably there is some unknown process which either favors matter production or sequesters antimatter as this occurred during the big bang.

  The apparatus would need to immediately separate the two to prevent an extremely large explosion.

right. im sure the physists working on this project know that, but im curious how much of a risk 100,000 matter/anti-matter pairs would make... i guess not much?

(can't edit first comment, sorry)

1kg of mass to energy (assuming every single particle met a corresponding antiparticle) would release a little over half the energy of the Krakatoa volcano eruption, similar to a 21 megaton bomb, so around the upper end of fusion bombs. Helium is about 99.5% the mass of the hydrogen that goes into it, so I guess those big fusion bombs must produce about 200kg of helium?

wow interesting, when you say "upper end" it means the effeciency of matter → energy conversion is at the upper end of fusion, or 1kg of anti-matter would have the same power of an upper end fusion?

either way super cool

I meant that 21 megatons is big enough to be among what the USA and USSR would have called their biggest H-bombs.

(megaton, to be clear, is not a measure of mass when talking about bombs, it's a measure of energy released - a 1 megaton bomb is equivalent to the energy released by a million tons of TNT, if such a volume could be detonated)

200000 hydrogen atoms has a mass of 201600 atomic mass units (about three haemoglobin molecules), which by e=mc² is about 188 TeV (tera electron volts), which is about 30 microJoules, or about 2% of the energy needed to register a key press on a mechanical keyboard.

thats amazingly cool way to put it, thanks ^^

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