![]() Then in the early 1980s, a new team, led by Gerard de Vaucouleurs, claimed that H_0 was about 100 km/s/Mpc, with an uncertainty of around ± 10. All the papers that came out around that time for over a decade - following the lead of Allan Sandage - agreed. In the 1960s, it was generally regarded to be about 50-to-55 km/s/Mpc, with an uncertainty of about ± 5. The same thing happened with the Hubble parameter (H_0): the physical parameter that measures the recession of galaxies and the expansion rate of the Universe. more detailed, but also uncertain, observations. The original 1929 observations of the Hubble expansion of the Universe, followed by subsequently. They published it anyway, even though another collaboration using the same neutrinos, ICARUS, had measured the speed of those neutrinos and found it to be consistent with c. They couldn't account for that anomalous result, but they couldn't find a flaw in what they had done. When OPERA came along, they measured a very different result - an outlier result - for a parameter that had already been previously measured. Other collaborations had measured the speed of travel for neutrinos under various energy conditions previously, obtaining a tight constraint that was indistinguishable from the speed of light. You might think that this is evidence for poorly executed science, but nothing could be further from the truth. When everything was attached properly, the anomaly went away, and the difference between the predicted and measured arrival times were reduced to < 1 nanosecond. The resolution turned out to be mundane: there was an error with the experimental setup in the form of a loose cable. ![]() The path of the neutrinos produced at CERN and detected in Italy. The result flew in the face of a century of experiments and one of our most hallowed and well-verified theories: Einstein's relativity. Neutrinos, of such low mass and such high energy, should travel at a speed indistinguishable from c, the speed of light. Instead, the neutrinos arrived 60 nanoseconds (6 × 10^-8 seconds) earlier than they should have, setting off a flurry of papers, speculations and wild explanations. ![]() The arrival time should have been very precise: 2.4 millliseconds after the collision that generated them, to an incredible accuracy. The way the experiment worked was simple, as neutrinos generated in the Large Hadron Collider were sent through the Earth (so that all the other particles would be absorbed by the intervening matter) and then detected hundreds of miles away in a very intricate setup. It's been five years since the OPERA collaboration announced a bizarre, unexpected and perhaps revolutionary result to a normal experiment: particles were observed to move faster than the speed of light - the ultimate cosmic speed limit - would allow. The OPERA collaboration famously observed a faster result a few years ago. ![]() Sending any particles through hundreds of kilometers of space should always result in the particles. ![]()
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