A horizontal line means the object is moving at a constant speed. The gradient of the line = the rate of change of speed. The steeper the line, the greater the increase in speed. The area under the ...

One of Albert Einstein's greatest insights was realizing that time is relative. It speeds up or slows down depending on how fast one thing is moving relative to something else. How much does it change ...

Alex Hutchinson is a National Magazine Award-winning journalist and Outside’s Sweat Science columnist, covering the latest research on endurance and outdoor sports. New perk: Easily find new routes ...

Many science fiction works feature time-traveling technologies and devices, but unlike physical travel by plane or train, time travel that travels through invisible time is hard to imagine. Kurzgesagt ...