Galilean Relativity

Galilean relativity is the idea that the laws of physics remain the same for observers in uniform motion relative to one another. This means that if you’re moving at a constant speed in a straight line, you can’t tell if you’re moving unless you look outside. For example, if you're in a smoothly moving train, you can't feel your speed or direction; everything inside appears normal. This concept laid the groundwork for later theories, like Einstein's relativity, by highlighting the importance of observing motion relative to different frames of reference.