Superposition is the geologic principle which explains why the bottom stratum in a section of rock is the oldest. The word literally means placing one thing on top of another where the lower strata are the older.
Answer:
In fact, you may point your flashlight (or laser pointer, if you prefer) at the Andromeda galaxy. There is a non-zero probability that one or more of the photons will be seen by some alien in that galaxy when they happen to glance into the sky at the Milky Way. However, you must take care to aim your flashlight not where Andromeda appears now, but where it will be in 3 million years. Good luck!
