How Acoustic Levitation Works

The idea that something so intangible can lift objects can seem unbelievable, but it's a real phenomenon. Learn how acoustic levitation takes advantage of the properties of sound to cause solids, liquids and heavy gases to float.

How LRAD Works

What makes sound a weapon? Review the basics of sound and discover exactly how the LRAD produces its "beam of sound." We'll also explore LRAD's hailing and warning abilities and other uses for sound.

How Radar Works

Radar seems to have infinite uses: Police use it to clock your speed, NASA uses it to follow satellites, meteorologists use it to track storms and the military uses it to track the enemy ... Learn all about radar technology!

Can two cans and a string really be used to talk over a distance?

I was watching an old movie today, and two kids (neighbors) were talking to each other using two tin cans and a string. Does that really work? If so, why does it work?

Do certain radio wave frequencies (like those used by cell phones) pose health risks?

Do certain radio wave frequencies pose health risks? If so, is it safe to live within a quarter mile of a cellular phone tower or a radio antenna?

What causes a sonic boom?

When an airplane flies faster than the speed of sound, you hear a large booming sound. But how can something that seems so simple cause such a boom?

What is a decibel, and how is it measured?

The decibel scale measures sound based on human hearing, which makes it one of the most unusual scientific measurements. How are decibel calculated and what do they tell us about sound?

What is white noise?

If you took all of the imaginable tones that a human can hear and combined them together, you would have white noise. This phenomenon gets its name from white light -- what do the two have in common?

Why can you hear the ocean when holding a seashell to your ear?

Do you remember holding a large conch shell up to your ear to hear the ocean? Why does this work even when you're far away from the sea?