Run a Thought Experiment
The cheapest simulation you can do is to run a “thought experiment.” Einstein was famous for his thought experiments. When he was only 16 years old, he imagined looking at himself in a handheld mirror. Then he imagined running faster and faster while holding the mirror out in front of him. “What will happen,” he wondered, “when I run as fast as the speed of light?” What would he see in the mirror?