Time

A new study suggests that the best time of day to exercise differs by sex. Evening exercise was found to be more effective for men, while results for women varied, with different health outcomes improving with different exercise times.

The movements of the Sun, Moon and stars have long been used to keep track of time, and now engineers from the University of Tokyo have proposed a new way to use the cosmos to precisely track time, using showers of particles from cosmic rays.

Britain's supercarrier HMS Prince of Wales has become the first surface ship to be equipped with a state-of-the-art atomic clock as it departs for the Exercise Cold Response 2022 NATO joint exercises off the north coast of Norway.

The flow of time isn’t as consistent as we might think – gravity slows it down, so clocks on Earth tick slower than those in space. Now researchers have measured time passing at different speeds across just one millimeter, the smallest distance yet.

DARPA has announced a new initiative called the Robust Optical Clock Network (ROCkN) program, which will look to develop a practical, super-accurate optical atomic clock robust and small enough to fit in a military aircraft, warship, or field vehicle.

Time crystals sound like something a video game character would be trying to collect, but this bizarre phase of matter is very real – and now one of them has been created in Google’s quantum processor, Sycamore.

We’re all familiar with the march of time, but why it does so is a mystery. In 2016 Australian physicist Joan Vaccaro proposed a new quantum theory of time, and now a team will test the hypothesis by searching for time dilation in a nuclear reactor.

Atomic clocks are our most precise timekeepers, with the best ones keeping time to within one second in 15 billion years. But there’s always room for improvement, as researchers at MIT have now demonstrated with a new quantum-entangled atomic clock.

Physicists in Germany have measured the shortest timespan ever recorded. The team measured the time it takes for a photon of light to travel the length of a hydrogen molecule, and found it to occur in just trillionths of a billionth of a second.

Time crystals are strange phases of matter that appear to break time-translation symmetry. Now scientists have observed two time crystals interacting for the first time, which could be a step towards practical applications like quantum computing.

Which time travel movie got the rules right? According to experiments using a quantum time travel simulator, reality is “self-healing,” so changes made to the past won’t drastically alter the future you came from – at least, in the quantum realm.

NASA has confirmed that a miniaturized, ultra-precise mercury-ion atomic clock currently in low-Earth orbit has been switched on.