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Comment by BAReF00t | Hacker News Reader

I’m disappointed.

I expected a project-Orion-type interstellar solution. Not a measly ”twice as fast as conventional“ water kettle.

Also, no word about what they will acually use. Because classic uranium is a quite limited resource actually. It has been said to run out even before fossil fuels.

Also, why not a fusion rocket? Given that we know how to make fusion bombs. Because until we find a massive amount of anti-matter, this will be the next best thing for a loong time. The only limiting factor would be a human body's ability to withstand G forces.

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All of those things are harder than a nuclear thermal rocket. Got to walk before you run. And a fusion reactor is actually likely to be much heavier than a fission one (at least in the near term).

They're using Low Enriched Uranium for this design. We have plenty of uranium (resources are huge, but no one bothers to prove them into reserves until the price is right), and not much is required for this project.

Don't be disappointed by the first step in a journey not taking you immediately to the destination.

> Because until we find a massive amount of anti-matter

I honestly hope this never occurs, or we never are able to contain/store such a mass for any real length of time.

Because if we can do it, it will be used for a weapon.

Seriously - I can't even imagine what - for instance - one kilogram of anti-matter coming in contact with regular matter - the amount of energy that would be released...it staggers the imagination. Today's fusion weapons release only a fraction of their potential energy; anti-matter conversion would be 100% (roughly):

https://en.wikipedia.org/wiki/Antimatter_weapon

"Using the convention that 1 kiloton TNT equivalent = 4.184×1012 joules (or one trillion calories of energy), one gram of antimatter reacting with one gram of ordinary matter results in 42.96 kilotons-equivalent of energy (though there is considerable "loss" by production of neutrinos)."

So...one kilo of anti-matter would be equivalent to 42 megatons - which is close to yield of the Tsar Bomba:

https://en.wikipedia.org/wiki/Tsar_Bomba

...but in a much more compact package. 50 kg of antimatter - which would be feasible for current launch systems, and comparable in size to current warheads:

https://en.wikipedia.org/wiki/W80_(nuclear_warhead)

Well - that's a 2 GT weapon...while I'm sure such a thing has been considered as to it's effects...I honestly don't know what that would be. Best guess might be that one such warhead could easily take out a good portion of say, the west coast (of the United States)?

Ultimately - we are not ready in any manner - socially, morally, politically - as a species to wield that kind of power responsibly. Honestly, even nuclear weapons fall into that assessment, despite recent history - I'm honestly not sure how we have gotten this far without a major nuclear war occurring.

Sadly, though, I know that my conjecture (in which I am not alone, I hope) will not do anything to stop the research - right now, though, the cost to produce anti-matter (let alone contain it) is so high as to make even a small mass cost an exorbitant amount of money. I sincerely hope there isn't any breakthrough on that front.

I honestly think we, as a species, are not ready for it (that isn't to say none of us are - but those who would be responsible with such "stuff" are likely very few - I know I am not one of them).

Who cares about weapon power? We already have _ridiculously_ and _maximally_ powerful weapons now. Our urge to kill one another is no longer constrained by the limits of our tools. It doesn't matter whether we're able to make even more powerful weapons.

Well, the Tsar Bomba was made as a single of a kind, ust for testing, and at half of its designed size because a bomb of that size is basically useless.

So I don't think we would get larger warheads. It's more likely we would get smaller ones, at power levels that can be used, and use their small weight as a feature. (Not something great, but I don't think we will ever use an Earth Crust removing bomb.)

Antimatter bombs emit mostly gamma radiation and so are unlikely to efficiently couple it to air. You would need a tungsten or lead (or even uranium) coupler to absorb the gamma radiation and heat up to drive the explosion.

Well, if we found it, it would already be contained unless accessed by definition.

Also, magnetic fields could definitely contain it, as is already done.

We can already make anti-matter, as it't essentially the process of making matter bounce off, using a photon, in such a way that it reverts its time direction. Or, in classical view: Turn a photon into a particle/antiparticle pair. The problem is, of course, that it first takes those shitloads of energy, that it would release later.

And to actually find anti-matter in nature, you would most likely have to turn into anti-matter yourself, travel back in time, and somehow survive the big bang without touching anything, to come out the hypothetized other side where time is reversed and anti-matter expanded to. Or try to get inside a black hole, and revert your direction of motion (as time and space are reversed in there). Both not yet technically available, to say the least. ;)

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