From the drivers perspective the bug smashed into the window at 70 mph while the driver was more or less stationary, but from the bugs perspective the driver came out of nowhere and smashed into it at 70 mph while the bug was more or less stationary. You can say “well obviously the driver was the one who smashed into the bug, they were going 70 mph!”, but that’s only because you’re using the earth as a reference frame, when in fact Einstein showed with general relativity that no such universal reference frame exists. We all agree to use the earth as a reference frame in our every day lives because how else would anything ever get done; there’s nothing wrong with that and its very convenient, but it doesn’t fully reflect the reality of their interaction.
From the drivers perspective the bug smashed into the window at 70 mph while the driver was more or less stationary, but from the bugs perspective the driver came out of nowhere and smashed into it at 70 mph while the bug was more or less stationary. You can say “well obviously the driver was the one who smashed into the bug, they were going 70 mph!”, but that’s only because you’re using the earth as a reference frame, when in fact Einstein showed with general relativity that no such universal reference frame exists. We all agree to use the earth as a reference frame in our every day lives because how else would anything ever get done; there’s nothing wrong with that and its very convenient, but it doesn’t fully reflect the reality of their interaction.