Time is relative. The ticking of the clock, even of the most precise clocks we can make, does not exist in an absolute. It ...

Time dilation, a captivating concept embedded in Einstein’s theory of relativity, has been experimentally validated on Earth. With the use of ultra-precise clocks, scientists have been able to ...

My telescope, set up for astrophotography in my light-polluted San Diego backyard, was pointed at a galaxy unfathomably far from Earth. My wife, Cristina, walked up just as the first space photo ...

"A three-body problem is extremely complicated. Now we're dealing with four: the sun, Earth, the moon and Mars. The heavy ...