# Spin behavior in entangled electron pair

daezy
Isn't it that in entangled electron pair, it's random which side will have
up and down spin... the two sides should produce opposite spin but the order is
random.. however I'm confused by the following statements:

"Recall that when you measure an electron's spin in one direction you
erase all information about the electron's spin in any other
direction. By this I mean the following: If I measure the spin in the
left/right direction I will always find it pointing exactly left or
exactly right. Say I measure it pointing left. If I measure it again
in the left/right direction then I will definitely see it pointing
left again. If I measure it in the up/down direction, however, then I
will have 50/50 odds of seeing it point either way. Once I do that
measurement, however, I will have fixed it to be pointing either up or
down, and a left/right measurement will once again yield 50/50 odds".

What is the above talking about? By using say up detector. You can
bias the pair to *always* produce up spin in that detector? But I
thought it's supposed to be random. Hope someone can clarify.