Is overpopulation real or legend?

The folks at Kurzgesagt are decidedly in the camp that believes in the grand scheme of things, the "legend of overpopulation" is not a cause for concern. Their case is based on a four-stage theory of demographic transition in a country or region: Read the rest

Charming animated primer on plant communication

Illustrator Yukai Du created this lovely animation of Richard Karban's TED talk on plant communication. Read the rest

Paradoxical undressing: getting naked before freezing to death

For reasons unknown, up to half of of people who freeze to death are found partially or completely naked. DNews looks into the phenomenon of paradoxical undressing. Read the rest

Mind-blowing explainer on fixed points

Understanding advanced mathematics can change how you see the world, so prepare for an eye-opening journey into the world of fixed points, courtesy of Michael at Vsauce. Read the rest

Why swirling spheres shift rotation at a certain number

Swirling a ball in a cup gets it spinning in the direction of the swirl, but adding six more starts them swirling in the opposite direction.

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Blow half of your mind with this explainer on brain hemispheres

CGP Grey explains that it might be better to think of your brain as two intelligences, with the mute right hemisphere forced to play sidekick to its conjoined twin.

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What makes dry quicksand so deadly?

Dry quicksand was a mythical substance — normal-looking sand that could swallow you in a flash. That is, until 2004, when scientists made the stuff in a lab. (Mark told you about that development.)

In this video, geologist Matt Kuchta explains how dry quicksand is different from both wet quicksand and stable sand. Hint: Think "Jenga". Read the rest

Khan Academy explains SOPA/PIPA

The globally praised Khan Academy comes out against SOPA and PIPA in this explainer video, which does a really excellent job of digging into the implications for legitimate sites (like Khan Academy) in a world where SOPA/PIPA become law. This is a great explanation of what SOPA and PIPA means for people trying to communicate with a broader public, but one thing to keep in mind as you watch is that there's another constituency that's missing: all the people who are using the net for other reasons: people who want to post videos of human rights abuses, who want to talk with other sufferers from a rare disease, who want to privately share private family moments with distant relatives. All these constituencies depend on services like YouTube and Twitter as a platform for communications, too.

SOPA and PIPA (via Waxy) Read the rest

Scary science, national security, and open-source research

I've been following the story about the scientists who have been working to figure out how H5N1 bird flu might become transmissible from human to human, the controversial research they used to study that question, and the federal recommendations that are now threatening to keep that research under wraps. This is a pretty complicated issue, and I want to take a minute to help you all better understand what's going on, and what it means. It's a story that encompasses not just public health and science ethics, but also some of the debates surrounding free information and the risk/benefit ratio of open-source everything.

H5N1, the famous bird flu, is deadly to humans. Of the 566 people who have contracted this form of influenza, 332 have died. But, so far, the people who have caught bird flu don't seem to have contracted the disease from other humans, or passed it on. Instead, they got it from birds, often farm animals with whom the victims were living in close contact. H5N1 was first identified 14 years ago, and there's never been a documented case of it being passed from person to person.

But that doesn't mean such a leap is impossible.

That's because of how the influenza virus works. Influenza is made up of eight pieces of RNA, containing 10 genes, and they all replicate independently of one another and there's no system for error correction*. That means you have more opportunity for mutations to arise that change what the virus does and who it can infect. Read the rest

Why would a battery burst into flame?

In several crash tests, the battery on a Chevy Volt began to heat up or burst into flame. The battery problems happened a few days or weeks after the impact and the National Highway Traffic Safety Administration is investigating. (One potential factor: NHTSA testers didn't drain the batteries of juice after the crash, which is recommended. As a comparison, it's standard practice to drain a gas tank after a similar collision. So this could be an issue of new technology learning curve.) If you want to better understand why a battery that's been through a car accident could burst into flame, I'd recommend reading this piece by the Midwest Energy News. It's a nice summary of how lithium-ion batteries work, and how they respond to damage. Read the rest