When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Einstein's theory of special relativity teaches us that time is relative. But what does it mean ...

We wouldn’t notice. Or we’d die. Depends on how much it changed. Relativity already tells us what would happen if the speed of light were to change, and the answer is nothing. Consider a stationary ...

Aircraft A and B are flying on the same horizontal plane, each with a constant speed. Aircraft A is traveling on a straight path, whereas the path of B is circular. We are interested in understanding ...

The reference frames from which observers view quantum events can themselves have multiple possible locations at once — an insight with potentially major ramifications. Imagine standing on a railway ...

The original version of this story appeared in Quanta Magazine. Imagine standing on a railway platform watching a trolley go past. A girl on the trolley drops a bright red ball. To her, the ball falls ...

If you took introductory physics, you learned about the “fundamental forces.” It goes something like this: All interactions are the result of one or more of five basic forces: strong nuclear, weak ...