Physics is the law. Everything else is a recommendation. Elon Musk first posted that on April 28, 2023. He later said the same thing about AI: if a model ignores physics, it can lie—because a rocket explodes and a car fails the second the math is wrong.

Light takes 8 minutes to go from the Sun’s surface to Earth. Getting out of the Sun takes far longer. Energy from the core wanders for 10,000–170,000 years because dense plasma keeps absorbing photons and firing them off in random directions. The warmth you feel today started that trip during the last Ice Age.

John McCarthy coined “artificial intelligence” in 1955 as the name for a Dartmouth summer workshop. He wanted the field to sound new. He later invented the programming language Lisp.

On July 20, 1976, Viking 1 made the first successful landing on Mars and sent back photos from the surface. The first image wasn’t a landscape. It was a close-up of one footpad — NASA wanted to know immediately whether the lander had sunk into Martian dust.