What's that awful smell? Cat urine? Semen? Rancid butter? Possibly one of these gorgeous city trees?

Today we’re going to talk about how we compare things that aren’t exactly the same - or aren’t measured in the same way. For example, if you wanted to know if a 1200 on the SAT is better than the 25 on the ACT. For this, we need to...

Hank talks about ancient sexy times, and how we know that early humans were getting it on with all kinds of folks.

Way out in the solar system, the heat of the Sun drops off dramatically, so the gas giants get just a tiny percent of the solar radiation that reaches Earth. Instead, their weather is fueled from the inside out!

For nearly half a century, scientists have been trying to create a process for transplanting animal organs into humans, a theoretical dream that could help the hundreds of thousands of people in need of a lifesaving transplant. But the...

We're taught to be cool around strange dogs because they smell fear, and that might be true, but your fear is probably freaking them out too!

What is this strange looking stuff? Is this branch just covered in fungus!? Well, it’s not fungus...but fungus DOES have something to do with it!

It's 1997. The United States Senate has called a hearing about global warming. Some expert witnesses point out that past periods in Earth's history were warmer than the 20th century. Because such variations existed long before humans,...

Reports of a fireball streaking through the sky are never a good sign after losing contact with a rocket.

It's always a little weird when a couple looks like they could be related, but Brit explains the science behind why it's not totally creepy! It involves percentages and kind of uncomfortable rating systems!

Paul Andersen shows you how to compare DNA sequences to understand evolutionary relationships. He starts with a brief introduction to cladograms and evolutionary relationships. He shows you how to classify DNA relationships using a...

What's it like to discover a galaxy -- and have it named after you? Astrophysicist and TED Fellow Burcin Mutlu-Pakdil lets us know in this quick talk about her team's surprising discovery of a mysterious new galaxy type.

Plants need light to survive. But apparently, that doesn't have to be sunlight.

Today we're going to discuss how machine learning can be used to group and label information even if those labels don't exist. We'll explore two types of clustering used in Unsupervised Machine Learning: k-means and Hierarchical...

In the first video in our two part series on HIV and AIDS, we explain how scientists figured out what HIV is, when the infection morphs into AIDS, and where they think the virus originated.

You might have stumbled onto those videos of people cutting sand for 10 minutes or of machines doing a repetitive task and felt an odd sense of satisfaction while watching them. Today, we look at the psychology behind those "oddly...

How do we know how old the Earth is? Learn how we date rocks, the moon, and planets.

We've found thousands of exoplanets over the years, but if we're going to find one that can sustain life, we need to take a look at the one planet we know that can, Earth.

Some emotions can feel so similar that you might mix them up and pick the wrong emotion.

Did you know the Soviet Union had its own Space Shuttle? Learn all about the Buran, what happened to it, and what innovations set it apart from its NASA counterpart.

What’s with all the "G"s and why do we keep having to develop new ones to use our phones in this technology.

Carbon-carbon double bonds are pretty common in nature, but triple bonds between carbons, called alkynes, are not. When alkynes do pop up in nature, it’s usually in a compound that’s toxic to humans, however, we can synthesize alkynes...

Designer Jared Ficklin creates wild visualizations that let us see music, using color and even fire (a first for the TED stage) to analyze how sound makes us feel. He takes a brief digression to analyze the sound of a skatepark -- and...

Asking questions almost always leads to finding answers, but those answers will often pose even more questions. Here are five mysteries started and later solved by science.