When we say 'Andromeda galaxy is 2 500 000 light years away from us do we mean 'now' or in a far past and can this past be calculated easily?

My class was learning the magnetic effects of current and one of the things we learnt was that the magnetic field strength produced by some conductor is going to be directly proportional to the current flowing through it. Now, by Ohm's Law, we also know that V = IR. So, if we do some temperature ...

My mechanics textbook defines work such that it involves a force that is exerted as the point of application moves through some distance. I'm confused how to apply this definition. Suppose you slide your hand across a table, such that friction exerts a force on the table but the table remains sta...