[ExI] Passive Observations

[Lee Corbin]

Not long ago, in a debate about simulations, someone said "subatomic
particles do change their state when observed".

I don't think that this is the right way to use the word "observe".

Suppose, for example, that I'm walking along a dark road and happen
to look up and see the star Regulus in Leo, and it causes me to wonder
what other stars are visible, and so I look over my shoulder and see in
almost the opposite direction the Andromeda nebula. Very possibly,
say, my eye has collected a photon from VJ00443799+4129236,
which is a binary star in the Andomeda galaxy.

In this case we say that I observed that photon or that I observed
the Andromeda galaxy.

But does my observing that photon or that galaxy actually cause
any state change in the atom of  VJ00443799+4129236 which
emitted that photon?  This emission occurred (in our frame of reference)
almost three million years ago, and we should avoid language that
suggests that my observation caused anything to happen there.

What people mean when they say "particles change state when
observed" is that if you try to observe something by bouncing a
photon off it, then you will indeed affect it. Likewise, if we were
all blind and we "observed" rocks by kicking them, then we'd
have to also say that "observation of rocks changes their state",
no doubt.

But as a *passive* collector of information that was generated anyway,
neither observers nor observations necessarily affect anything.

Lee