kottke.org posts about relativity

Gravitational waves detectedFeb 11 2016

Lights Askew In Heavens

After a potential detection of gravitational waves back in 2014 turned out to be galactic dust, scientists working on the LIGO experiment have announced they have finally detected evidence of gravitational waves. Nicola Twilley has the scoop for the New Yorker on how scientists detected the waves.

A hundred years ago, Albert Einstein, one of the more advanced members of the species, predicted the waves' existence, inspiring decades of speculation and fruitless searching. Twenty-two years ago, construction began on an enormous detector, the Laser Interferometer Gravitational-Wave Observatory (LIGO). Then, on September 14, 2015, at just before eleven in the morning, Central European Time, the waves reached Earth. Marco Drago, a thirty-two-year-old Italian postdoctoral student and a member of the LIGO Scientific Collaboration, was the first person to notice them. He was sitting in front of his computer at the Albert Einstein Institute, in Hannover, Germany, viewing the LIGO data remotely. The waves appeared on his screen as a compressed squiggle, but the most exquisite ears in the universe, attuned to vibrations of less than a trillionth of an inch, would have heard what astronomers call a chirp -- a faint whooping from low to high. This morning, in a press conference in Washington, D.C., the LIGO team announced that the signal constitutes the first direct observation of gravitational waves.

The NY Times headline above is from when the concept of gravitational lensing suggested by Einstein's theory of relatively was confirmed in 1919. I thought it was appropriate in this case. Wish they still ran headlines like that.

A man outfitted his family minivan withMar 08 2007

A man outfitted his family minivan with high-precision cesium clocks to demonstrate to his kids that they gained 22 nanoseconds of vacation time on their mountain camping trip than they would have at a lower altitude.

A moving mass has been shown toMar 24 2006

A moving mass has been shown to generate a gravitomagnetic field (just like a moving electrical charge creates a magnetic field) and "the measured field is a surprising one hundred million trillion times larger than Einstein's General Relativity predicts". (via rw)

A relativistic examination of gravity in theOct 11 2005

A relativistic examination of gravity in the galaxy may indicate that the invention of dark matter may not be necessary to solve the not-enough-matter problem. "The motions of stars in galaxies is realized in general relativity's equations without the need to invoke massive halos of exotic 'dark matter' that nobody can explain by current physics."

Update: mjt has doubts about the paper referenced here and notes that there's other evidence for dark matter that is not questioned by the above study.

Brian Greene on Einstein's most famous equation,Oct 05 2005

Brian Greene on Einstein's most famous equation, E =mc^2. When he finally gets around to it in the middle of the article, Greene's got a pretty good layman's explanation of what the formula actually means.

PBS has put up a companion webAug 18 2005

PBS has put up a companion web site to the Nova program on Einstein airing in October. Features include audio clips of several physicists describing e=mc^2 to non-physicists.

Brian Greene on Albert Einstein's miracle year,Apr 08 2005

Brian Greene on Albert Einstein's miracle year, his discovery of the photoelectric effect, and his uneasiness with quantum mechanics.

Tags related to relativity:
physics Albert Einstein science

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