Comment by cool_shit

You are right, according to quantum mechanics. If you have a pair of electrons in a product state and measure the spin of one of them, you instantly know what the "other particle's" spin is going to be (if you knew what the initial state was). When you "peek at a card", you "make a measurement" and alter the system.

For anything that exists outside of a light-cone around the first electron, a measurement of the second electron will be truly random from the measurer's perspective.