
This is the key to understanding the Lorentz Transformation.
With COVID-19 putting a damper on social activity, “the gang” doesn’t get together very often, but we still gather occasionally (and carefully). One of the times recently I got into how, even though we’re all sitting essentially motionless in a living room, we’re moving through time at the speed of light. I explained why that was, and they found it pretty cool.
Then I ran into someone online who just couldn’t wrap his head around it — just couldn’t accept it (despite explaining in detail and even providing some links). Physics is sometimes challenging to our daily perceptions of reality!
However in this case, it’s just a matter of some simple geometry.