Ruled by Relativity

Walking on two legs, time and space seem universal, but take a good look at the universe, and things start to get mushy. Chad Orzel defines time with a circular-sounding title, writing “there isn’t a giant master clock at the center of the universe that everybody sets their watches by.” Although time can only be measured in ticks, two clocks are seldom in agreement. Chad says “Scientists in Colorado have clocks so good they can measure the change in time from moving at walking speed, or from moving one foot higher in elevation.” On Starts With a Bang, Ethan Siegel revisits the speed of light in a vacuum, which nothing apparent can exceed. If you’re a proton instead of a photon, your speed limit is a little bit lower, thanks to interaction with the cosmic background radiation. New upgrades to the Large Hadron Collider will boost the top speed of its protons by 8 m/s, only 3 m/s short of lightspeed.

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Leaving Light in the Dust?

Last month, a team of researchers announced that their neutrinos appeared to be travelling faster than the speed of light. Ethan Siegel explains that the mass of a neutrino is “less than one-millionth the mass of the electron, but still not equal to zero” and “should move at a speed indistinguishable from the speed of light.” Meanwhile the OPERA team had to smash 1020 protons just to detect 16,000 neutrinos—and account for every source of delay an uncertainty in their experimental setup. On Uncertain Principles, Chad Orzel explains that the researchers used GPS satellites to measure the 730 kilometer distance between the proton source and the neutrino detector to within 20 centimeters, and synchronize the atomic clocks at each site. Chad writes “superluminal particles that interact with ordinary matter (as neutrinos do, albeit weakly) opens the door to violations of causality—effects happening before the things that caused them, and that sort of thing.” Steinn Sigurðsson writes on Dynamics of Cats, “Well, along with 99.87% of physicists, I am very skeptical,” but adds “a very, very faint possibility is that either relativity is wrong; or, muon neutrinos are weakly tachyonic; or, the neutrino tunneling between flavours is evidence of some funky stringy higher dimensional tunneling, and the geometry is weakly non-3D.” The OPERA team wants to know: can you spot the error?