Last week, the science world was abuzz with the news that gravitational waves had been discovered thanks to the LIGO project and the team of international scientists that made it possible. At WUWT, I covered the story here, saying that it was a “triumph of science”. Indeed it was, and still is, and the effects of this discovery on science will ripple into the future for decades and centuries to come.
I woke in the middle of the night as I sometimes do, for no particular reason except that my brain doesn’t always cooperate with my body when it comes time to sleep, and the LIGO project was on my mind, partly due to an email I got from a fellow who wanted to tell me about a colleague in China who was talking about Gravitons and the LIGO announcement here. It got me was thinking about how wonderful it was that we could detect a gravitational wave from the merging of two black holes 1.3 billion years ago:
A computer simulation shows the collision of two black holes, a tremendously powerful event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO. LIGO detected gravitational waves, or ripples in space and time generated as the black holes spiraled in toward each other, collided, and merged. This simulation shows how the merger would appear to our eyes if we could somehow travel in a spaceship for a closer look. It was created by solving equations from Albert Einstein’s general theory of relativity using the LIGO data.
The two merging black holes are each roughly 30 times the mass of the sun, with one slightly larger than the other. Time has been slowed down by a factor of about 100. The event took place 1.3 billion years ago.
The stars appear warped due to the incredibly strong gravity of the black holes. The black holes warp space and time, and this causes light from the stars to curve around the black holes in a process called gravitational lensing. The ring around the black holes, known as an Einstein ring, arises from the light of all the stars in a small region behind the holes, where gravitational lensing has smeared their images into a ring.
The gravitational waves themselves would not be seen by a human near the black holes and so do not show in this video, with one important exception. The gravitational waves that are traveling outward toward the small region behind the black holes disturb that region’s stellar images in the Einstein ring, causing them to slosh around, even long after the collision. The gravitational waves traveling in other directions cause weaker, and shorter-lived sloshing, everywhere outside the ring.
Wikipedia’a article on LIGO notes that on 11 February 2016, the LIGO and Virgo collaborations announced the first observation of a gravitational wave.The signal was named GW150914.The waveform showed up on 14 September 2015, within just two days of when the Advanced LIGO detectors started collecting data after their upgrade. It matched the predictions of general relativity for the inward spiral and merger of a pair of black holesand subsequent ‘ringdown’ of the resulting single black hole. The observations demonstrated the existence of binary stellar-mass black hole systems and the first observation of a binary black hole merger.
This is indeed a wonderful and marvelous thing, as is the dual LIGO observatory itself; one in Hanford, WA and the other in Livingston, LA, two identical observatories separated by 3,002 kilometers (1,865 miles) so that this distance corresponds to a difference in gravitational wave arrival times of up to ten milliseconds, making it possible to do triangulation to determine an approximate location.
Wikipedia also had this note about the facility and it’s history:
The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect gravitational waves. Cofounded in 1992 by Kip Thorne and Ronald Drever of Caltechand Rainer Weiss of MIT, LIGO is a joint project between scientists at MIT, Caltech, and many other colleges and universities. Scientists involved in the project and the analysis of the data for gravitational-wave astronomyare organised by the LIGO Scientific Collaboration which includes more than 900 scientists worldwide, as well as 44,000 active Einstein@Home users. LIGO is funded by the National Science Foundation (NSF), with important contributions from the UK Science and Technology Facilities Council, the Max Planck Society of Germany, and the Australian Research Council. By mid-September 2015 “the world’s largest gravitational-wave facility” completed a 5-year US$200-million overhaul at a total cost of $620 million.
That’s quite an endeavor, combining global collaboration, two large nearly identical facilities, and decades of research and construction. It struck me that it wasn’t just human energy that went into making LIGO a reality, but scads of real energy, to support design, construction, and operation of LIGO over that time.
Speaking of construction, here’s a photo from 2011, showing what looks to be a vacuum vessel being offloaded from a semi truck by a portable crane truck. Obviously, the vessel was built elsewhere and trucked in, and you can say that about essentially every aspect of the two observatories, as there was nothing but barren land in their place before.
It looks like one of these units:
Imagine the energy involved, not just in construction and transportation to the site by truck, but in maintaining a near perfect vacuum in the 4KM dual legs of the observatory, such as the one seen below:
The amount of power needed is substantial, and it must be clean and non-intermittent as this internal newsletter for the Livingston site suggests:
One of the challenges of our rural location is the availability of clean and stable electrical power. Initially we found our electrical supply experienced some instabilities. This prevented the proper operation of the air conditioning system and some of the vacuum pumps. As mentioned in Cecil Franklin’s article above, the local power company which supplies the observatory, DEMCO, has completed construction of a separate substation dedicated solely for LIGO use. This feature has dramatically improved the quality of electrical power and all electrical systems are now operational. In addition, this improvement significantly reduced power outages due to thunder and lightning storms. Thank you, DEMCO!
Imagine if the power goes out. How long would it take to re-establish the vacuum in that facility?
A quick look at DEMCO Electrical COOP in Louisiana says they use coal-fired power plants, such as:
The coal-fired Big Cajun Power Plant located in Pointe Coupee Parish was built jointly by Louisiana’s electric cooperatives in the 1970s to provide wholesale electrical power to cooperative members across the state. Today, the facility is owned by Louisiana Generating, a subsidiary of NRG Energy.
And, a plot of power generation sources in Louisiana suggests that fossil fuel (coal and gas) and nuclear power make up the lion’s share of power generation in the state:
For the Hanford LIGO site, the Washington state power generation balance is different, using more hydro than coal or gas:
The point here is that LIGO couldn’t operate without a stable power supply, and couldn’t run on a power grid fed primarily on solar or wind, but instead uses the most hated power generation methods of environmentalists; coal, gas, nuclear, and hydro. Try doing this sort of science with intermittent solar and wind power – you can’t.
This need for stable power to run LIGO may have been a factor as to why the Pasadena, CA based California Institute of Technology chose to put observatories outside of California, where the vagaries of wind and sunshine wouldn’t affect the grid, and they wouldn’t have to worry about environmental political issues as much.
And it seems, the LIGO staff are big fossil fuel enthusiasts themselves, where in Hanford, they have a hot-rod club at the Lab:
Don’t tell the EPA.