I. Obviously named after Galileo Galilei, Galilean relativity states that the laws of physics should be the same in all inertial reference frames. Inertial reference frames means any frame of reference that isn’t accelerating or decelerating. If either of those are the case, there is no experiment that can “prove” someone in one frame is really moving and someone else in another isn’t because the laws of physics are the same in both instances.
For example, someone in a plane 30,000 feet in the air could say the plane is stationary and the earth is moving away from it. Someone on the ground could say the plane is moving and the earth is stationary. With Galilean relativity in mind, they’re both right because they can’t perform an experiment that clearly determines one is moving and one isn’t.
It sounds obvious to us now, but to Galileo and his peers, it was revolutionary. Galileo thought about it like this:
“Shut yourself up with some friend in the main cabin below decks on some large ship,” Galileo wrote. If the ship was moving at a constant speed in one direction and you dropped a ball, it would drop to your feet in a perfectly straight line. But a fish outside of the boat, let’s say with x-ray vision (we’re thinking hypotheticals here folks), would see the ball move down and forward, even though you yourself didn’t see that change. If the ship didn’t have any portholes and you just woke up below decks and couldn’t remember how you got there, you would not be able to tell if you were on dry land “standing still”, or moving. That’s Galilean relativity and it helped explain why we can’t feel the motion of the earth.
But it also explains an existential crisis each of face at least once in our own lives, if not more.
You see, in Galilean relativity the motion has to be constant because as soon as we felt the acceleration or deceleration, we’d know we’re the ones in motion.
This phenomenon helps explain why after being stuck somewhere for too long in life, we feel like we’re not moving forward. Whether you’re living in your hometown you swore to escape as soon as you could, or working the same job you are when you graduated college, or hanging out with the same group of friends you’ve had since middle school, a long period of constant motion makes us dull to the experiences of life’s motions. On the other hand, this is why starting a new job, getting into a new relationship, or moving somewhere new makes you feel alive. That acceleration reminds you that you are actually in motion–it’s just a bit slower at some points than at others.
This sounds a bit sad, but it’s actually quite encouraging. Galilean relativity helps explain why college feels like such a drag of doing the same thing for four years until that exciting day of graduation. You’re moving at a slow, constant speed freshmen - junior year which makes it difficult to notice how far you’ve come until you get to the destination. Then you get to senior year and it flies by because at least once a week you get a jolt of acceleration through job interviews, filling out graduation paperwork, and experiencing those bittersweet Friday nights. Somehow, it feels like you just moved into your dorm last month and four years just went by in an instant. Though that didn’t practically happen, it did in theory.
Everyday you woke up, went to class, went to work, studied, and went to sleep. That cycle moved you forward at a constant speed, making the same amount of progress each day, but you just never noticed. You were like the person beneath decks of a ship with no portholes. Friends and family members, on the other hand, were able to see your slow, steady progress the whole time. To them, college really did feel like four years.
Obviously since this is all a theory, I’m hesitant to provide any thing further than making an observation, but I will say if you’re struggling with the effects of Galilean relativity in your everyday life, try to force some functions of acceleration. This could be (again, just proposing how this might work) taking a vacation, trying something you’ve always wanted to try, learning a new hobby, or anything else that could remind yourself that you’re actually in motion, though it may be little, and slowly moving forward.
Question is: are you going where you want to end up, or have you just been hanging on to the tide?