Can we accurately describe light as exclusively a wave or just a particle? Are the two mutually exclusive? In this third part of his series on light and color, Colm Kelleher discusses wave-particle duality and its relationship to how we...

Biofuels can provide energy without the reliance on environmentally harmful fossils fuels -- but scientists are still searching for a plentiful source. Craig A. Kohn demonstrates how cellulose, the naturally abundant tough walls of plant...

In this final segment on the four fundamental forces of physics, Hank tackles the magnetic force, the second of the two ways in which electromagnetism is apparent in the universe

The ability to recognize sounds and identify their location is possible thanks to the auditory system. That's comprised of two main parts: the ear, and the brain. The ear's task is to convert sound energy into neural signals; the brain's...

In this video Paul Andersen explains how the perceived frequency of a source depends on the motion of both the source and the observer. As a source approaches an observer the frequency will increase and as it moves away it will...

In order to have a meaningful conversation about the dangers of radiation exposure, it’s important to be clear about just how much radiation we are dealing with. Unfortunately, the units we use are kind of a mess… but SciShow is here...

We learn a lot about our surroundings thanks to sound. But... what is it exactly? Sound, that is. What is sound? And how does it travel? And what is this Doppler Effect that we've heard so much about? In this episode of Crash Course...

In the past 3,000 years, many populations have evolved genetic adaptations to their local environments. People in Siberia and the high arctic are uniquely adapted to survive extreme cold. The Bajau people can dive 70 meters and stay...

There’s no doubt that fish is a great source of protein in one’s diet. But the debate about whether fish farming or commercial fishing is worse for the environment continues and, as you might suspect, there isn’t a straightforward answer.

Stretched across a tree-peppered expanse in Southern Africa lies the ruins of Great Zimbabwe, a medieval stone city of astounding wealth. Located in the present-day country of Zimbabwe, it's the site of the second largest settlement...

Voyager 1 may be out of our solar system (and 40+ years old) but we're still getting plenty of new data from our interstellar space probe.

Although coal is such an amazing energy source that we've kept using it despite the harm it causes, today we may be better poised to stop using it than at any previous time in history.

With sandwiches and toast, sourdough bread always adds an extra accented flavor to your meals. But where does the signature tartness come from?

Why do dogs eat grass? A look at your pup’s wild relatives may give you a sense of what dogs’ diets are really like.

A lot of work goes into managing our impact on the environment and its impact on us. That work is the work of environmental engineers. In this episode we’ll explore water quality, air quality, noise pollution, waste management, and more.

If you go to the store in search of milk, there are a dizzying number of products to choose from. There's dairy milk, but also plant-based products such as almond, soy, and oat milks. So which milk is actually best for you? And which...

Silicon transistors allowed computers to shrink from the size of houses to watches in a short time, but engineers are facing a problem: we've almost hit the limit on how small silicon transistors can get.

Did you know that your body's fight-or-flight response to danger may, in part, come from inside your bones? Plus, another study suggests that vaping may impair to your ability to fight off lung infections.

NASA's Cassini spacecraft has detected a huge ocean under the surface of Saturn's moon Enceladus. But how? And what does it really mean? Hank lays out the data -- straight from space to your brain!

This week, we're headed north. To check out the gods of the Northmen. Or the Norse. That's right, we're talking Thor, Loki, Freyr, Freya, Odin, Frigg, Baldr, and Tyr. And Fenrir. And the Frost Giants. There's a lot to cover here, and...

In previous decades, most news with global reach came from several major newspapers and networks with the resources to gather information directly. The speed with which information spreads now, however, has created the ideal conditions...

So... do plants need dirt? The truth might shock you. In this episode of Crash Course kids, Sabrina talks about how plants get energy and how that energy is transported around them. Also, she talks about dirt.

In which Stan Muller teaches you about our third branch of Intellectual Property, trademarks. A lot of people confuse trademark and copyright. Trademarks apply to things like company and product names and logos, packaging designs, and...

In this video Paul Andersen explains how energy can be transferred from one system to another. In a closed system the energy can be transferred as either work or heat. Thermal energy transfer is know as energy transfer through heat. ...