Senior Editor Cord Jefferson reports on the recent exodus of Facebook users:
I told you last month why I thought everyone should get off Facebook, and it turns out people listened. Though the social networking behemoth continues creeping toward 700 million global users, six million Americans quit the site in the month of May. That’s the first time Facebook has lost U.S. users in over a year. The site also posted losses in Canada, the U.K., Norway, and Russia, while most of its gains came in countries in the developing world, including Mexico and India.
What explains the stunted growth? Several things, the first of which is a growing concern about privacy amongst Facebook users. It was inevitable that a social site that turned its users into a commodity for advertisers would eventually be a turnoff for some, and that looks to be happening at Facebook en masse. Beyond that, competing sites like Twitter, which demand less engagement and information from users, are also siphoning away some former Facebook loyalists.
Read more on GOOD.
Making the Impossible Decision
On August 12, 1961, immediately before the construction of the Berlin Wall this couple makes the decision to pass their son over barbed wire to West Berlin.
The original caption:
A German fate at the fence of barbed wire!
It may be that a couple from Berlin will never see each other again because it became separated by the drawing of the line across Berlin. On August 12, one day before Ulbricht had ordered to surround West Berlin with barbed wire, a man was flying into West Berlin. His wife should follow him a few days later as the little son was still in a holiday-camp. In the meantime the nearly impenetrable “iron curtain” was drawn around West Berlin. The couple met at the fence of barbed wire. The “Vopo” guard was indulgent and allowed the meeting. The couple discussed their situation and they decided that the little son shall grow up in freedom. At a moment when the “Vopo” did not watch them the mother handed the child over the barbed wire.
New 3-D imaging of nebulas demonstrate that they are more than just flat blobs of pretty gas and debris that you can’t stop clicking on your dashboard. More at the Hubble site, plus a “how it’s made”!
(via io9, above is the Helix Nebula)
Most people are familiar with the Doppler effect—in which the frequency of a wave changes depending on the motion of the observer relative to the wave source—from the shifting pitch of sirens as they pass. But the effect is important for pressure waves in addition to acoustic waves. When an object moves through air, its motion disturbs the surrounding air via pressure waves, which travel at the speed of sound. If an object moves slower than the speed of sound (top right), then those pressure waves extend in front of the object, carrying information about the object and allowing the air to shift and move smoothly around it.
If the object is moving at the speed of sound (bottom left), then it arrives at the same time as the pressure waves. In essence, the object is striking a stationary wall of air—this is what was meant by “breaking the sound barrier”. At Mach 1, the physics of the problem have fundamentally shifted. Now the only way for air to deflect to allow the object’s passing is by the sudden compression of a shock wave.
Moving even faster than the speed of sound (bottom right) the pressure and sound waves created by the object’s motion stretch in a cone behind it. The cone, known as a Mach cone, is the shock wave that deflects air around the moving object. The result is that the object will actually pass an observer before the observer will hear it. This is because no information can travel forward of the Mach cone’s leading edge. That’s why the area outside of the Mach cone is sometimes called the Zone of Silence. When the Mach cone passes an observer, the shock wave will register as a boom, like when the space shuttle passes overhead while landing. (via fyeahchemistry)