# When matter and anti-matter collide

Do they create energy? Or do they just disappear with zero energy?

If they create energy when disappearing, that means it takes energy to create them, right?

If they disappear into zero energy, could that be a clue about how to create matter from nothing?

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The do not disappear with zero energy.

Their energy (both that originating from rest mass and any kinetic energy) appears somehow. As photons, a spray of other (lighter) particles, etc.

For instance, when an electron meets a positron (that is, a anti-electron) the most common result is a pair of gamma rays each of 511 keV (in the center of momentum (CoM) frame of the $e$--$e^+$ pair). It has to be at least two because you have to conserve both energy and momentum (and angular momentum, too, but that is a complication we will ignore for the moment), and that also tells us that there have opposite momenta in the CoM frame.

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