thought experiment

A thought experiment is an experiment that can be described but is not actually performed. Instead, it is carried out by the mind, using reasoning and logic. Thought experiments have been used by great thinkers since ancient times, and they are still used today to explain concepts such as quantum physics and relativity. These "virtual experiments" help us explore the world.

What it is: a virtual experiment carried out by the mind
Famous "thought experimenters": Galileo, Newton, Einstein
When it's used: often in astronomy and physics to understand something about the Universe
How it's done: 1) Ask a question; 2) visualize the situation; 3) make a prediction based on logic; 4) develop a theory.

Image credits: main image: Eric Hamilton.