A particle and its antiparticle meet, and both are converted into radiation. Set the antimatter mass on a logarithmic slider from 1 nanogram to 1 gram, pick electron–positron or proton–antiproton, and the panel reports the total energy released by E = 2mc², the TNT equivalent, the number of annihilation events and the energy each one carries.
Antimatter Annihilation
A particle meets its antiparticle and both are converted into radiation. Set the antimatter mass and watch E = 2mc² — the 2 is there because an equal mass of ordinary matter is destroyed alongside it. Switching species changes how the energy is parcelled up, never how much there is.
What Is the Antimatter Simulator?
The antimatter simulator is a free interactive physics lab that runs in your browser — nothing to install and no sign-up. Set the antimatter mass, pick electron-positron or proton-antiproton, and see the energy released by E = 2 m c squared. It reports total energy released, annihilation events and energy per event 2mparticlec² as you drag the sliders.
| Control | Range | Step |
|---|---|---|
| Antimatter mass | 1 ng - 1 g (logarithmic) | — |
How to Use the Antimatter Simulator
The mass slider is the only input that changes the total. It sets the antimatter mass from 1 nanogram to 1 gram on a logarithmic scale, and the energy readout tracks it in a straight line — ten times the mass, ten times the joules, with the TNT equivalent following in the same step. Everything else on the panel describes how that energy is packaged, not how much of it there is.
The two species buttons are the point of the tool. Switching from electron–positron to proton–antiproton multiplies the energy per event by about 1836 and divides the number of events by the same factor, leaving the total untouched. That is the fact most people find surprising, and it is easiest to believe when you watch the two readouts move in opposite directions. The bars underneath the animation show it directly: they are drawn on one shared logarithmic scale, so the events bar slides left by exactly the distance the energy-per-event bar slides right, and the total marker never leaves the centre. This is annihilation as an accounting identity — the same energy, counted two different ways.
The formula the sim solves is E = 2mc², with c = 299792458 m/s, and the same arithmetic is available step by step in the E = mc² calculator. The 2 is there for a physical reason worth stating plainly: annihilation destroys the antimatter and an equal mass of ordinary matter along with it. Antimatter cannot annihilate alone. Supply a gram of positrons and a gram of electrons goes too, so two grams are converted, not one. The c² in the middle is the exchange rate between mass and energy that Einstein’s equation fixes — an enormous number, which is why so little mass buys so much energy.
That factor of two is also the misconception the tool exists to correct. A gram of antimatter is widely quoted as 9×1013 J, the figure you get from mc² alone. Drag the slider to 1 gram and the readout shows 1.79751e14 J instead — 42.96 kilotons of TNT, not 21. Seeing the doubling appear on a live readout is what stops it being an abstraction. One caveat the panel states rather than hides: with protons, roughly half of each event leaves as neutrinos that no collector can catch, so the energy released and the energy usable are not the same number, and the simulator never quietly multiplies one into the other.
Frequently asked questions
What does the antimatter simulator calculate?
It calculates the total energy released when a given mass of antimatter annihilates, using E = 2 m c squared. Set the antimatter mass anywhere from 1 nanogram to 1 gram and the simulator reports the energy in joules, the same figure as a TNT equivalent, the number of individual annihilation events that mass represents, and the energy carried by each one. Choosing electron-positron or proton-antiproton changes how that total is divided up between events, but never the total itself.
Why does the energy not change when I switch particle type?
Because the total depends only on the mass you annihilate, not on what the mass is made of. E = 2 m c squared has no term for the kind of particle. A proton is about 1836 times heavier than an electron, so one gram of antiprotons is 1836 times fewer particles than one gram of positrons, and each annihilation releases 1836 times more energy. The two factors cancel exactly. Watch the two lower bars in the simulator move the same distance in opposite directions while the total marker stays pinned in place.
Why is the formula E = 2 m c squared and not E = m c squared?
Because annihilation destroys two masses, not one. Antimatter cannot annihilate on its own: it needs an equal mass of ordinary matter to meet, and both are converted. If you supply one gram of antimatter, one gram of ordinary matter goes with it, so the mass actually converted to energy is two grams. E = m c squared is still the underlying rule; the factor of two simply accounts for the matter that the antimatter takes with it.
How much energy is in 1 gram of antimatter?
About 1.8 times 10 to the 14 joules, which is roughly 43 kilotons of TNT. The exact figure the simulator reports is 1.79751e14 J, or 42.96 kt. That is a common place to slip: a gram of antimatter is often quoted as 9 times 10 to the 13 joules, which is what you get from m c squared alone and misses the gram of ordinary matter destroyed alongside it. Set the mass slider to its maximum and the readout shows the doubled figure directly.
Can this energy actually be used?
Not usefully, for two separate reasons. Electron-positron annihilation ends in gamma photons, so almost all of that energy is in principle catchable, but proton-antiproton annihilation produces about five pions per event and roughly half the energy escapes as neutrinos, which pass through any collector without interacting. The larger obstacle is production: antimatter has only ever been made in accelerators, in quantities measured in individual atoms, at an energy cost vastly greater than anything the annihilation returns. The simulator reports the energy released, not energy gained.
References & formula source
- Griffiths — Introduction to Elementary Particles, chapter on particle dynamics and annihilation processes.
- Particle Data Group (Lawrence Berkeley National Laboratory) — Review of Particle Physics, particle masses and proton–antiproton annihilation channels.
- CERN — Antimatter topic pages, on production quantities and the matter–antimatter asymmetry.
- Further reading: Annihilation — Wikipedia