Physical Science

When there's a suspect in a crime and the evidence includes a handwritten note, investigators may call in handwriting experts to see if there's a match. How exactly do experts go about analyzing someone's handwriting?

By Julia Layton

I recently bought a pair of mirrored sunglasses and they are already scratched. Isn't there a way to make them scratch-resistant?

They stick around long after death and compete with the likes of Dracula, Frankenstein's monster and the Wolfman as one of the great figures of classic horror movies. Are you brave enough to unravel the history of these real-life, tangible ghosts?

By Tom Harris

The human eye misses a lot -- enter the incredible world of the microscopic! Explore how a light microscope works.

By Craig Freudenrich, Ph.D.

Iran has announced its activation of a second set of uranium centrifuges. These machines are at the core of the uranium-enrichment process. Find out where the centrifuge fits into the equation.

By Marshall Brain

For centuries, curious observers have probed the heavens with the aid of telescopes. Today, both amateur and professional scopes magnify images in a variety of ways.

By Craig Freudenrich, Ph.D.

More than 2.3 billion people across the globe drink alcohol, but most don't consider it a drug. But if you've ever seen someone who's had too much, you know alcohol has profound effects on the mind and body.

By Craig Freudenrich, Ph.D. & Michelle Konstantinovsky

Smoking or chewing tobacco makes many people feel good, even mildly euphoric. It's the nicotine that produces the buzz. Find out how nicotine affects the human body and what makes it so addictive.

By Maria Trimarchi & Ann Meeker-O'Connell

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?

What exactly is an atom? What is it made of? What does it look like? The pursuit of the structure of the atom has married many areas of chemistry and physics in perhaps one of the greatest contributions of modern science!

By Craig Freudenrich, Ph.D.

Biting on aluminum foil can be painful -- basically, when you bite on foil, you build a battery in your mouth. Ouch!

Helium is the second lightest element on the Periodic Table. How is helium created?

By Patrick J. Kiger

You may know a bit about polygraphs, but do you know which physical reactions it actually monitors?

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?

By Sascha Bos

I recently used chlorine bleach to clean the siding on my house, and I was amazed at how well it worked! What is bleach? How does it remove stains? Is the chlorine in bleach the same as the chlorine in drinking water or in swimming pools? Is chlorine safe to use?

By Yara Simón

Just how far can the human eye see? There's no exact formula to figuring it out, but we do have an idea.

By Patrick J. Kiger

What is dioxin? There's a lot of discussion going on in my town about dioxin and its dangers.

I once saw this device shaped like a light bulb. It had a vertical support inside it, and on that support there were four vanes with four diamonds on the end. One side of the diamond was black and the other was white. I did a little research and found out that it was called a Crookes' radiometer -- how does it work?

I have a thin piece of plastic mounted on the back window of my RV. It magnifies things so I can see better when I'm backing up. How can such a thin piece of plastic magnify things? A regular glass magnifying lens would have to be curved on both sides and much thicker.

By Austin Henderson

Bullet size is measured in calibers, but how are wires and nails measured? Learn about bullet size and caliber in this article.

Many ads for new clocks advertise their ability to automatically synchronize themselves with the atomic clock in Boulder, Colorado. This atomic clock is more precise because it uses the frequencies of atoms as its resonator.

Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.

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?

By Austin Henderson

Radar is used to track storms, planes, and weapons and also to create topographic maps. Learn about radar, radar technology and Doppler shift.

By Marshall Brain

Nuclear materials get used in many forms of nuclear medicine -- everything from PET scans to chemotherapy uses them. Learn how nuclear medicine works.

By Craig Freudenrich, Ph.D.