Light is the fastest-moving thing in the universe. So what would happen if the speed of light were much, much slower? In a vacuum, the speed of light is about 186,000 miles per second (300,000 ...

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch ...

The speed of light is a fundamental constant, approximately 299,792,458 meters per second. It's the same for all observers and hasn't changed measurably over billions of years. Nothing can travel ...

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 ...

In the realm of physics, the speed of light is considered one of the most fundamental constants in the universe, dictating the structure of time and space as we know it. But what if this cornerstone ...

The idea was first hypothesized about 70 years ago. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. In a bizarre repercussion of Albert ...

The internet is such a slowpoke. In principle, it should operate at nearly the speed of light, which is more than 670 million miles per hour. Instead, internet data moves 37 to 100 times slower than ...

Breakthroughs, discoveries, and DIY tips sent every weekday. Terms of Service and Privacy Policy. Back in 2018, astronomers examining the ruins of two collided ...

The Parker Solar Probe, currently the fastest human-made object, travels at 0.05% the speed of light (approximately 330,000 mph). Reaching 1% the speed of light requires an immense amount of energy ...

Chris Impey receives funding from the National Science Foundation and the Hearst Foundation. Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, ...