From the beginning of the universe to the present day, it's one of the few things we regard as regular and unchanging. But is it really so constant? We take a look at the physics of time.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.
Thank you for signing up to Live Science. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.