Congrats to the Laser Interferometer Gravitational-wave Observatory (LIGO) team for directly detecting gravitational waves for the first time.
LIGO was the NSF’s most expensive project, and took scientists basically from the 1960’s to 2015 to fully realize – initially nobody believed it was possible to actually build this instrument.
Two detector locations with perpendicular 4 km 4-mirror laser interferometers were able to detect gravitation waves from a billion year-old blackhole collision:
Direct Gravitational Wave Measurement of Two Black Holes Merging in 1/10 of a second!
The graph is very interesting and raises the questions:
- do the pre-impact lobes represent the outer limits (presumably thinner than the center) of the black holes merging?
- the slope of the lines in the main chirp are very steep … are those spikes much taller (or infinite) than we can resolve?
- what do the small post-impact lobes mean exactly?
(The local speed of light in a medium is a constant, while gravitation waves distort space, thus changing an interference pattern.)
Basic science is always valuable, but just a few of the reasons why this experiment is important:
- confirm the equations originally proposed by Einstein in 1915 for gravitation in the GTR and Standard Model
- confirm experimentally that light and gravitation waves have different propagation characteristics
- develop the technology to make observations at the sub-proton level
- study large-scale cosmic events (black holes, colliding galaxies, supernova, binary star systems)
- study the time of the Big Bang, as gravitational waves are not filtered like EM waves
- confirm or deny cosmic observations and theories made in the EM spectrum, and provide advance notification of occurring events for study in the EM spectrum.
More generally, measurement tools are the highest form of technology, whether for time, space, EM, or gravity. Any investment of time or money in measurement tools is easily repaid 1000x. For example, the GPS system is the result of accurate time measurement using “atomic clocks.”
This decade is an exciting time for science, as several major terrestrial and space instruments come online or are upgraded.
It will be interesting to see if anybody develops a table-top model of LIGO. Experiments in the 60’s with non-laser methods were susceptible to ambient vibrations, but we’ll see. Cryogenics would likely have to be involved since random atomic motions are larger than the signal being acquired.
LIGO Detects Gravitational Waves for Third Time
Gravitational Waves Detected 100 Years After Einstein’s Prediction
SIGNAL PROCESSING WITH GW150914 OPEN DATA
LIGO black hole echoes hint at general-relativity breakdown
On the time lags of the LIGO signals HN
Gravitational waves from a binary black hole merger observed by LIGO and Virgo
LIGO Architects Win Nobel Prize in Physics
LIGO and Virgo announce the detection of a black hole binary merger from June 8, 2017