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50

Don't be there when the antimatter beam arrives. There is no shortage of ways to destroy a spaceship: high-powered lasers, antimatter particle beams, near-lightspeed projectiles, and so on. There's no reliable way to shield a ship against energies of this level. Instead, the basic defense is maneuver. Nothing travels faster than light. The Moon is a ...

46

No. The mass of a proton is about $1.67\times10^{-27}$ kg. Therefore the total maximum energy released by its annihilation with an antiproton is $2mc^2= 2\times1.67\times10^{-27}\times9\times10^{16} = 3\times10^{-10}$ Joule. This is not much. Even if all this energy would be deposited inside the victims brain, it is a very small amount. But it would not. As ...

43

The mass-energy in a gram of anti-matter is $0.001 c^2 = 9 × 10^{13}$ joules or about 20 kilotonnes of TNT, that is substantial! (and you get another $9 × 10^{13}$ from the annihilation of the equivalent matter On the other hand, if you accelerate 1g of anything (matter or antimatter) to 0.99 c, it has a kinetic energy of $0.001c^2/\sqrt(1-0.99^2) - 0.001 c^... 43 There's a very simple bit of math that tells you how far an antimatter projectile can penetrate something, assuming that the massive amounts of energy released aren't involved in that penetration. As the bullet passes through the target, it will annihilate itself with the matter in the target at a 1:1 ratio. Meaning that the bullet can make contact with no ... 42 The bullet will not go far It depends somewhat on the cross-section of the antimatter bullet. Let's assume that the bullet is slightly under 10mm in diameter, giving it a cross-section of 0.0000762 square metres. Passing through 1000m of air it will encounter head-on 0.0762 cubic metres of air, which conveniently is 3 moles. The molar mass of dry air is ... 40 Potentially, it would be very similar to life made out of matter. Antimatter is expected to have the same chemistry as normal matter, so any lifeforms would work the same way with the exception that if they even touched our world they would instantly annihilate. However! There is a lot about physics we don't know. Under the assumption that antimatter is ... 27 Lets take a look at destructive power. Matter-antimatter annihilation yields all of the available resting energy of both the antimatter and the matter it's annihilating. This may be more than you expect. In fact it's at least 43 kilotons per gram. The kinetic energy of the impactor is nothing compared to that. Since your aliens are looking at weaponising ... 25 The main problem with antimatter would be containment. You cannot simply put it into a normal container, because the normal container would be made of matter, and the antimatter would annihilate with it. So you need to find a way to keep the antimatter safely away from any matter in your ship. At the same time, you also need to allow it to safely be ... 25 Anti-matter is still not easily store-able but is instead made on-demand inside the ship in some kind of "charge reversal chamber" (possibly with the aid of some kind of 'unobtainium' which would then become the defacto fuel being bought and sold in place of the anti-matter it produces). since anti-matter cannot be stored the maximum damage your ships can ... 23 Expense of containing it How do you contain anti-matter in a safe way? I don't know, but someone does in your story. It may be that containing anti-matter is so energy expensive that the only way to power a long-term anti-matter storage unit is with an anti-matter reactor. In that case, only the people with the money to operate anti-matter reactors in the ... 22 Just like us But don't touch them. Lots of science fiction likes to attribute special or near magical properties to antimatter. This is rubbish. The only thing special about anti-hydrogen, is if you touch it with hydrogen, they annihilate in a tremendous release of energy. Two atoms of anti-hydrogen and one of anti-oxygen would still make one molecule ... 20 Of course it's plausible. The only thing that's slightly more out there in the realm of science-fiction is where they got the antimatter. As you know antimatter is identical to ordinary matter in every way except that the particles it is made of have an opposite charge. This means by manipulating magnetic/electric fields it can be effectively contained ... 20 No. Positron emission tomography is regularly used to scan brains. PET detects gamma rays created when positrons, emitted by an injected radio tracer undergoing positron emission decay, annihilate with electrons in the patients tissue. For example, a brain scan using 18F-FDG has an effective radiation dose of 14 mSv [1], which is on the order of the ... 19 Jon's Law: Any interesting space drive is a weapon of mass destruction. Basically, you're in a setting where the average person who can pay is already in possession of a personal WMD. Adding antimatter simply makes the existing problem that much worse, so no, there really is nothing you can do about it. 17 Make the antimatter charged and use a magnetic bottle to keep it contained. It will reach its target without touching matter. On impact, the magnetic bottle mechanism breaks and the antimatter escapes. The bullet may be a little bulky, but some hand waving miniturizations should get it small enough to fire out of a weapon. Depending on the size, you may ... 16 Anti-matter is currently stored using electric fields on time scales of minutes. In order to store it with gravity, you need to invent a device that can generate gravity (or negative gravity, if that is a thing?) Here is an article about theories for a gravity generating machine, though it is pretty short on the facts. Asking for science-based on this ... 16 Assume, for starters, that the antimatter weapons produce and fire the simplest kind of antimatter beam. Namely, a beam of positrons. Once your vessel detects an incoming beam of positrons, it aims its own antimatter beam weapons in the direction of the attacking vessel. Both positron beams will be positively charged. This will cause them both deflect and ... 16 There are really two problems you should be thinking about here, but luckily they both have reasonable solutions. The question you asked: Use of home-made antimatter bombs against military assets. You're thinking "how do I keep home-made antimatter bombs out of Joe Schmoe's hands, but a military ship isn't really going to be worried about that. Joe ... 16 Unfortunately, it wouldn't increase the yield. When matter and antimatter annihilate each other, yes, they do liberate a huge amount of energy. But, you don't get energy for free - no matter how it's produced, creating antimatter will take up exactly as much energy as annihilating it will release. So, even if it were plausible that a fission or fusion bomb ... 14 Use the electromagnetic spectrum Humans already communicate at long distances using radio waves, and see using visible light. Photons have no charge, so it's safe to use visual displays, or any wave on the EMS that isn't ionizing, to converse. Antimatter particles will not be annihilated when coming in contact with photons from matter, and matter won't ... 14 First of all, I think we need to clear up the science a little bit. Anti-matter doesn't 'explode' when it comes in contact with matter - it mutually annihilates both itself and the matter that it comes into contact with in equal quantities of mass, becoming pure energy. This means that in essence, the anti-matter bullet is far more efficient at creating ... 13 Similar question but with a moon made up of antimatter. Is it realistic to have a moon made of antimatter? My proposition there: Cut some chunks off. You can do this using a laser. In the linked moon scenario you would have to blast stuff up and away from the moon because it would be too dangerous to approach. Your smaller chunk is more tractable in ... 12 Let's say the bullet is a standard .308 Winchester round with a diameter of 7.85mm which means the bullet is encountering:$\pi * 3.925^2 * 1000 = 48,400$cubic mm of air. The density of air at 20 degrees C is$1.2 KG / m^3$which means the bullet is encountering around$0.058$grams of air per meter of its flight path. Via$E=MC^2\$, a total of 0.116 ...

11

I'll address storage of antimatter, because that is the one thing in your question humans have done successfully so far. While we may someday build an antimatter-based propulsion device, it's a ways off. Storing antimatter is another story. Currently, the best way to store antimatter is a Penning trap. It uses a magnetic field and an electric field to store ...

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Since we don't know the density of the beam, we don't know if there's any hope of protecting the ship from a hit. I will assume that we're not talking lightsabers here. That is, a ship could take several shots assuming it maneuvers to prevent the damage from piling up in one area. Cover your ship in an ablative armor made to soak up the anti-matter ...

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A regular gun uses an explosive that generates hot gas, and the expansion of this gas propels the bullet. Antimatter annihilation produces a large amount of gamma radiation, (when protons annihilate they the direct quark-quark annihilation produces hard gamma rays, and an rain of unstable pions that soon decompose into more gamma rays and neutrinos) The ...

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One thing which other posters have not mentioned is the effects of the interplanetary medium on the asteroid and mining operation. Before you can do anything, it would be very wise to "clear" the area around the asteroid. A massive "wake shield" in an orbit slightly ahead of the antimatter asteroid will create a zone of extremely hard vacuum behind it, and ...

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There's a very relevant xkcd - What if? on this. Granted, the projectile is not made from antimatter, and it's a bit bigger than your bullet. However, it does discuss speeds at which "the atoms are literally passing through each other". That's in the section about 99% the speed of light. It also mentions that air atoms penetrate roughly three meters into a ...

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Well... I work with antimatter as a Physicist and I could object that your dragon would probably not have enough energy to do anything :( Let me explain it a little bit better: the big problem with antimatter is confinement: antimatter has the tendency to annihilate with matter, so your dragon should have a built-in electromagnetic trap inside his own body ...

9

Taken shamelessly from my previous answer here If you absolutely, positively need to sterilize the surface, you must blast it from orbit. It's the only way to be sure. The problem you'll quickly run into is that the Earth is big. You can crash 10km sized asteroids into it, and there'll still be some survivors to whine about the injustice of it all. Now, ...

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