There are always a lot of things happening in outer space – probes, launches and explorations to keep us busy – but this week seems something special. Something pretty too, I would add. And something that will likely change physics as we know it now.
(Credit: ICRAR)
Number one: we discovered a few galaxies hidden just behind the Milky Way. Somehow, we had missed them until today. “The Milky Way is very beautiful of course and it’s very interesting to study our own galaxy but it completely blocks out the view of the more distant galaxies behind it.” (Staveley-Smith, ICRAR). The team at ICRAR identified 883 galaxies -a third of which had never been seen before – just next door (250 million light years from Earth). It seems there’s a lot of stuff we don’t know yet even in our neighbourhood read the whole story here).
Number two: we found two black holes merging into one for the first time. The two circled and eventually collided to form one giant black hole. “It’s a runaway process. The closer they get, the faster they spin. Near the end, they were whirling so fast that each orbit lasted just a few milliseconds. When they eventually merged, the single black hole that remained was 62 times the mass of the sun – three solar masses lighter than the two original black holes combined.” (Kip Thorne, Caltech, one of LIGO’s founders and yes, the technical consultant for the movie Interstellar).
Event that led us directly to… number three: gravitational waves. I say it again. Gravitational waves. Sounds like something you’d never bump into during your lifetime. Well, it just happened.
(Waves from two black holes colliding. CREDIT: Zuse Institute Berlin)
To be fair, this spooky stuff had already made a lot of noise last year (we thought we had finally detected them. It turned out to be a false alarm.) This time, however, things seem different: LIGO, the Laser Interferometer Gravitational-Wave Observatory, has finally given us a proof – detection of the waves coming from the merging of the two black holes I mentioned above. “That missing mass all went into creating gravitational waves that fluttered space-time like a sheet. The total power output of gravitational waves during the brief collision was 50 times greater than all of the power put out by all the of the stars in the universe put together. It’s unbelievable.” (Kip Thorne).
Why does this discovery matter so much?
Well, gravitational waves, like antimatter and Higgs boson (just to mention other famous ones) have been known in theory -Einstein predicted their existence of the waves since 1916- long before we had the instruments to prove they were real. In their case, we deal with echoes of massive objects moving all over the cosmos and cataclysmic events that produce ripples in the space-time fabric of the universe (for a more technical definition of gravitational waves, read this. And no, they are not gravity waves – here for the disambiguation.) They provide us unique insight on weird objects in space, and they will probably change our understanding of how it works.
“The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. (…) Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.” (LIGO Press release, 11 February 2016)
As a matter of fact, you can even hear them. Translating in sound waves, they emit a chirp (a short rise in the background noise) – hear it:
Exciting eh? I bet a Nobel Prize is already on the way .
Actually *hearing* them is an incredible experience…
Indeed – it gave me shivers!