Gravitational waves detected for the first time

Credits: R. Hurt/Caltech-JPL In a historical scientific landmark, researchers have announced the first detection of gravitational waves, as predicted by Einstein's general theory of relativity 100 years ago. This major discovery opens a new era of astronomy. For the first time, scientists have directly observed "ripples" in the fabric of spacetime called gravitational waves, arriving at the Earth from a cataclysmic event in the distant universe. This confirms a major prediction of Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. The observation was made at 09:50:45 GMT on 14th September 2015, when two black holes collided. However, given the enormous distance involved and the time required for light to reach us, this event actually occurred some 1.3 billion years ago, during the mid-Proterozoic Eon. For context, this is so far back that multicellular life here on Earth was only just beginning to spread. The signal came from the Southern Celestial Hemisphere, in the rough direction of (but much further away than) the Magellanic Clouds. The two black holes were spinning together as a binary pair, turning around each other several tens of times a second, until they eventually collided at half the speed of light. These objects were 36 and 29 times the mass of our Sun. As their...
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Driverless cars see fewer crashes than human-driven cars

domain-b: Self-driving cars are involved in fewer crashes on average than vehicles with a driver behind the wheel, a study released on Friday by the Virginia TechTransportation Institute shows. The study was commissioned by Alphabet Inc's Google unit, which has reported a series of minor crashes involving its self-driving fleet. It looked only at Google's fleet of more than 50 self-driving cars, which has logged 1.3 million miles in Texas and California in self-driving mode. The test fleet has reported 17 crashes over the last six years, although none were the fault of the self-driving cars, Google said. After adjusting for severity and accounting for crashes not reported to police, the study estimated cars with drivers behind the wheel are involved in 4.2 crashes per million miles, versus 3.2 crashes per million miles for self-driving cars in autonomous mode. Crash rates for conventional vehicles at all severity levels were higher than self-driving crash rates, the study found. A 2015 National Highway Traffic Safety Administration study found about 60 percent of property-damage-only crashes and 24 percent of all injury crashes are not reported to the police. California law requires all crashes involving self-driving vehicles be reported to police. Google spokesman Johnny Luu said the company asked Virginia Tech "to look...
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