First direct detection of a gravitational wave
The science team from the Laser Interferometer Gravitational-wave Observatory (LIGO) announced today that on September 14, 2015 they made the first direct detection of a gravitational wave, produced by the merging of two distant black holes.
Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About three times the mass of the sun was converted into gravitational waves in a fraction of a second — with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals — the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford — scientists can say that the source was located in the Southern Hemisphere.
According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide at nearly half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. These are the gravitational waves that LIGO observed.
Because of the faintness of the wave signal, I suspect that the scientists involved have spent the last four months reviewing their data and the instrument very carefully, to make sure this was not a false detection. That they feel confident enough to make this announcement tells us that they think the detection was real.
Recently ESA launched Lisa Pathfinder, a prototype space-based gravitational wave detector designed to test the technology for building a larger in-space observatory that would be far more sensitive that LIGO. Funding for that larger detector has dried up, Today’s announcement will likely help re-energize that funding effort.
More information here.
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The science team from the Laser Interferometer Gravitational-wave Observatory (LIGO) announced today that on September 14, 2015 they made the first direct detection of a gravitational wave, produced by the merging of two distant black holes.
Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About three times the mass of the sun was converted into gravitational waves in a fraction of a second — with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals — the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford — scientists can say that the source was located in the Southern Hemisphere.
According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide at nearly half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. These are the gravitational waves that LIGO observed.
Because of the faintness of the wave signal, I suspect that the scientists involved have spent the last four months reviewing their data and the instrument very carefully, to make sure this was not a false detection. That they feel confident enough to make this announcement tells us that they think the detection was real.
Recently ESA launched Lisa Pathfinder, a prototype space-based gravitational wave detector designed to test the technology for building a larger in-space observatory that would be far more sensitive that LIGO. Funding for that larger detector has dried up, Today’s announcement will likely help re-energize that funding effort.
More information here.
Readers!
My annual February birthday fund-raising drive for Behind the Black is now over. Thank you to everyone who donated or subscribed. While not a record-setter, the donations were more than sufficient and slightly above average.
As I have said many times before, I can’t express what it means to me to get such support, especially as no one is required to pay anything to read my work. Thank you all again!
For those readers who like my work here at Behind the Black and haven't contributed so far, please consider donating or subscribing. My analysis of space, politics, and culture, taken from the perspective of an historian, is almost always on the money and ahead of the game. For example, in 2020 I correctly predicted that the COVID panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Every one of those 2020 conclusions has turned out right.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
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