Lasers
Laser guns are possible in the future. If we could magniy the beam enough it could destroy various things. That is why those small laser pointers destroy the cells in your eyes and could eventually damage your eyesight.
Another thing we would have to do to have weapons like in the movies is to make it in short blasts. If it wasn't a short blast it would always be on and would be very dangerous. To make it this way we would have to block it with a mechanisim to cur the beam at regular intervals.
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