Science Dictionary

The kilometer (km) is a standard unit of measurement used in the metric system. Derived from the French "kilomètre," the unit is used to measure length and distance along a straight path.

By Mitch Ryan

In any scientific research, there are typically two variables of interest: independent variables and dependent variables. In forming the backbone of scientific experiments, they help scientists understand relationships, predict outcomes and, in general, make sense of the factors that they're investigating.

By Marie Look

Physicist and cosmologist Stephen Hawking was a fierce spirit who symbolized the foibles and complexities inherent in human nature. Learn more about him by taking our quiz.

By Nathan Chandler

As much as we might like to think that our collective knowledge has unlocked most of the mysteries of the universe, we've really only got a hold on a tiny fraction of the knowledge required to fully understand it all-and it's a weak hold at best. But every once in a while a new theory [...] The post 12 Of The Most Mind-Blowing Scientific Theories Ever Conceived appeared first on Goliath.

By Wes Walcott

From astronauts to doctors to an archaeologist, we present eight scientists whose contributions to science, engineering and math were inseparable from their identities as Indigenous Americans.

By Dave Roos

Questions, theories and debates about quantum physics can get muddled because of a number of myths and misconceptions. Here are four of them.

By Alessandro Fedrizzi & Mehul Malik

Under the right conditions, hot water can somehow freeze faster than cold water. It's called the Mpemba effect. We'll explain how it happens.

By Dylan Ris

Einstein famously called the phenomenon "spooky action at a distance," and physicists just won the Nobel Prize for their work on it, but what is quantum entanglement?

By Andreas Muller

The world often seems chaotic and events appear to occur randomly, but what's the difference between chaos and randomness?

By Mitchell Newberry

How do scientists find details about the early days of our solar system? One way is to investigate comets. Find out how the Deep Impact spacecraft fired an impactor into Comet Tempel 1 to get some answers.

By Carolyn Snare

Scientists announced the discovery of the largest known planet in the universe. TrES-4 has a density similar to balsa wood, and some say this gas giant could float on water. Learn why this planet is so puzzling and how planet hunters make amazing discoveries like these.

By Jacob Silverman

Every day, astronomers unravel a little more of the universe's inner workings, but the jury is still out on 95 percent of its contents.

By Robert Lamb

You've heard of the big bang, of course, but do you have any idea as to what was happening during that massive flurry of activity billions of years ago?

By Robert Lamb

So much of our cosmological history starts with the much-discussed Big Bang, but what led up to that cataclysmic moment? And did time even exist back then?

By Robert Lamb & Patrick J. Kiger

So much about galaxies remains a mystery. We know what they're made of and that we live in one (the Milky Way), but how many galaxies are in the universe?

By Craig Freudenrich, Ph.D.

Space collisions are the universe's car wrecks. Only in outer space, it's stars, asteroids and even galaxies doing the smashing.

By John Fuller

He starred with Superman, drove the getaway car at Pluto's demise and was voted sexiest astrophysicist by People magazine. Is there anything Neil deGrasse Tyson can't do?

By Laurie L. Dove

He is famous for a phrase he never said, for wearing turtlenecks and for hosting the original 'Cosmos' TV series. As enthusiastic about the stars as he was about marijuana, Carl Sagan led a very surprising life.

By Laurie L. Dove

If you have a theory that potato chips are making you fat (with the proof being your expanding waistline), you've just used two scientific terms in a very unscientific way.

By Beth Brindle

He built President Eisenhower an indoor golf-training machine, analyzed the Zapruder film and searched for an Egyptian pyramid's treasure chamber using cosmic rays. Aren't you dying to meet this wide-ranging scientist?

By Nicholas Gerbis

The man who had some theories about relativity was also an eccentric who gleefully eschewed socks, dodged German military service and spurned social conventions.

By Nicholas Gerbis

Frequency has to do with wave speed and wavelength is a measurement of a wave's span. Learn how frequency and wavelength of light are related in this article.

By HowStuffWorks.com Contributors

Comets are remarkable pieces of our universe's past, and they tell us a great deal about how the universe was formed. Learn about the long but rewarding process of discovering and analyzing comets.

By Craig Freudenrich, Ph.D.

A black hole occurs when a massive star dies -- its enormous mass implodes and becomes so heavy that it bends space. So how do astronomers detect something that they can't see?

By Craig Freudenrich, Ph.D.

Have you ever really thought about the scale of the universe? A good starting point is the teaspoon.