Electrons naturally move with a speed less than 1% of the speed of light, but we can accelerate them to speeds of more than 99% of the speed of light by providing billions of electron volts of energy! Interestingly, we couldn't accelerate electrons to 100% of the speed of light as the faster the electrons move, the heavier they become. At those speeds, they require a tremendous amount of energy to increase their speed, even by 0.000000001%.
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