Universe may revolve once every 500 billion years — and that could solve a problem that threatened to break cosmology

An illustration of outer space with stars whizzing by.

In 1929, astronomer Edwin Hubble published a paper demonstrating that the universe is expanding. It gave rise to the Hubble constant, the number that describes how fast the universe is expanding.

But it eventually created a puzzle, called the Hubble tension, because this cosmic expansion differs depending on what cosmic objects are used to measure it.