Two antimatter questions

I’m in the process of writing a short sci-fi story and need some help with the antimatter.

QUESTON 1) What would the energy discharge of a single anti-hydrogen and a single hydrogen atom be? Are we looking at a molecular sized explosion? The equivalent of a fire cracker maybe? 100,000 ton nuclear warhead?

Generally speaking all of my anti-mater knowledge comes from the discovery channel and Star Trek. It is a very small part of the story, but I would like to have some accuracy.

Thanks to all

You’re looking at a two atom size explosion. That’s it. Two proton masses are converted into energy. How large could that possibly be?

Did you mean to post a second question?

Orders of magnitude of energy in Joules:

So one atom’s not enough to cause an explosion capable of doing any damage by itself, and is only 100000th as big as one second of moonlight on a face. If, theoretically, the resulting energy from the explosion is absorbed and reemitted as visible light by the surrounding air and went right into your eyeball you could probably see it, but I’ll bet you couldn’t.

Assuming E=mc^2, 28 milliJoules ((3*10^8)^2 * (1.602 * 10^-19 * 2)).

ETA: Isn’t regular fission different from antimatter annihilation? If not, what’s wrong with my math?

You used the proton’s charge, not its mass.

Your proton mass, which should be 1.67 x 10[sup]-27[/sup] kilograms. 1.60 x 10[sup]-19[/sup] is the fundamental unit of charge in Coulombs.

Go gett’im cowboy!! Chronos to the rescue!! :stuck_out_tongue:

Note that the “explosion” between a lepton and its antiparticle (like an electron) is simply going to give you two photons at about 511keV each (in the gamma ray area of the spectrum); energetic, certain, but hardly noteworthy by themselves. Indeed, in positron emission tomography, a patient is injected with a radiopharmaceutical compound containing a radioactive isotope of fluorine, which then emits a positron (anti-electron) via weak interaction decay. The positron then typically interacts with an electron, annihilating both and radiating the above mentioned gamma rays *right inside the patient’s brain, which are then detected by the scanner, and translated into images of the functioning brain that the technicians and doctors see in real time.

A hydrogen-antihydrogen reaction is more complex. Even if we eliminate the electrons and just consider the proton-antiproton interaction, the result isn’t as simple because unlike electrons, protons and their antiparticles are not fundamental particles; they’re composite systems of smaller particles. The resulting string of reactions, virtual created and destroyed particles, locally deconfined quarks, et cetera is likely to produce not only photons but a lot of short-lived exotic leptons (muons, tau leptons, maybe crazier stuff) and a bunch of neutrinos which will flit through solid matter like dimes through a hole in your pocket.

A single reaction wouldn’t be perceived by anything but a very sensitive radiation counter, even though it could do significant damage to an individual cell. Even a lot of them wouldn’t necessarily cause a visible explosion per se; any explosion (i.e. a shockwave through a gas or continuum medium) would require the gammas to be absorbed and converted into thermal motion. If you have enough of them being produced at one time to interact with the air (I’m assuming this is taking place in atmosphere) they would ionize the air, making it glow and even (at high enough energy flux) rapid heating, resulting in an explosion.


Hey thanks to everyone. I knew it was going to be tiny but I didn’t know exactly how small. I originally thought that it might be visible to the naked eye but now I doubt it.

As to my second question, um, well that part was supposed to be deleted when I copied the question originally from Word but obviously I flaked :smack: . So I’m going to go with

QUESTION 2) Soooo, how YOU do’n?


Thanks again to everyone for some great answers!