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.
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
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.
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