Tag Archives: relativity

What are the quanta in quantum gravity? A hundred years ago Einstein said “space”. So where are we now?

Quantum gravity is all the rage in physics these days. There are books about it but none say what quantum gravity is. And none report real progress. We should be upset about this. Really! Quantum gravity tries to reconcile our two immensely successful—but mutually inconsistent—theories about the world: quantum theory and relativity. A quantum theory […]

An amazing birthday present: a universe that allows time travel and helps us understand our existence

In 1949 Austrian-American logician Kurt Gödel gave a friend a strange birthday present: a rotating universe. Gödel is widely regarded as the world’s greatest logician. Albert Einstein, the greatest physicist, was his best friend. For years they walked home from the Princeton Institute for Advanced Study almost every day. The present—for Einstein’s 70th birthday—dealt with […]

Understanding time travel . . . and travel time

Albert Einstein predicted time travel in 1905. It was demonstrated in 1971 and many times since. The twin paradox provides a dramatic illustration of time travel: You travel to a distant star and return to find you are far into your twin’s future. No-one has done this; but it is a real effect. It has […]

Physics has long been confused about the concept of ‘now’. New insights show that it is fundamental.

A sense of Now is the universal human experience. Yet modern physics cannot handle the concept of the present moment. Indeed relativity—our great theory of space and time—insisted on embedding it within a time dimension and then crossbreeding this dimension with three space dimensions to make spacetime. This was a blunder. It blocks progress. Physics […]