Physics for Everyone, Lecture 6. The Unification of Space and Time

2026-10-19

Everything we have discussed in these lectures so far has brought us to this, the first 20th century revolution in physics. And that is the way it should be, but it is most definitely NOT the way it is normally taught in physics classes.

One of my pet peeves about the teaching of physics is how Special Relativity is introduced in introductory physics, as if it is some insight from God that Einstein had. Instead of the Ten Commandments, Einstein was given a tablet that said: “The speed of light is the same for all observers, regardless of their relative motion to the source of the light” and everything followed from that.

No! Maxwell’s unification of electricity and magnetism taught us something fundamental about light, that it is an electromagnetic wave. From that, the equations of electromagnetism allowed Maxwell to derive the speed of light using only measurements of electricity and magnetism.

It was the brilliance of Einstein to realize that this result was inconsistent with the rest of classical physics, in particular the results of Galileo about the nature of motion.

And from there, Einstein was inevitably dragged to equations of special relativity.

And only after he followed through, did someone else, his former math teacher, Minkowski, realize that Einstein had discovered something deep about the connection between space and time, and they symmetries of nature.

That is the actual story I describe here. It is elegant and beautiful, and much more sensible than the “Einstein revelation” fable that is too often used in the teaching of physics.

I hope you enjoy this. The culmination of classical physics, and the beginning of the modern era.

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The Origins Podcast features in-depth conversations with some of the most interesting people in the world about the issues that impact all of us in the 21st century. Host, theoretical physicist, lecturer, and author, Lawrence M. Krauss, will be joined by guests from a wide range of fields, including science, the arts, and journalism. The topics discussed on The Origins Podcast reflect the full range of the human experience - exploring science and culture in a way that seeks to entertain, educate, and inspire. lawrencekrauss.substack.com

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