Gravitational Waves Detected
Gravitational Waves Detected, NSF
“For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at Earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window to the cosmos.”
Hanford’s scientists finally spill gravitational-wave secrets – but they still can’t tell all, Geekwire
“Meanwhile, there are already rumors that LIGO registered more readings that aren’t yet ready to be reported.”
– Observation of Gravitational Waves from a Binary Black Hole Merger, Physical Review Letters
– The First Sounds of Merging Black Holes, Physics
Keith’s note: Taxpayers have seen more than $600 million spent on LIGO yet NSF purposefully shut off their live webcast from their LIGO event well before it was completed. Why would taxpayers want to hear what the scientists have to say?
Again Einstein’s General Theory of Relativity is confirmed, this time in a massive way. What a great day in science.
Massive, indeed :_>
Should this bear out and prove correct, then this and the detection of the Higgs are probably two of humanities greatest feats towards understand the complex details of our universe, reality and existence. Unfortunately, most of the US public is not interested or does not understand such ramifications.
‘Two of humanity’s greatest feats towards understanding the complex details of our universe, reality, and existence?’
Seems a little presumptuous and dismissive of so much that has gone before. On what scale of judgment and by what criteria? Just how long is your list? I hope the underlying theories themselves (and the many discoveries that enabled them) are somewhere in the contest.
Steps forward, certainly, but baby steps at best. Surely all involved would agree that while we are “cracking” baryonic matter, much of the universe remains outside our limited knowledge.
Humanity’s greatest feats are before us.
Another discovery that should lay the foundations for new physics which one day when harnessed will enable human interstellar travel.
Awesome. This will allow… gravity surfing!
Big stepping stone to LISA.
Now that the discovery has been made Earthside I wonder what the space-borne LISA brings? More accuracy, or perhaps a lower threshold?
This question is answered even on the LIGO wikipedia entry as it’s such an obvious one. LISA (or rather eLISA) will address a different spectrum of frequencies and strains.
You can find plots online of other GW detectors and what types of astrophysical phenomena they can detect. LISA is an extremely technically challenging mission. That’s one reason why the “pathfinder” mission was created to help to buy down the technical risk. The science also needs to be prioritized relative to other scientific priories, e.g., exoplanets, dark matter, etc. Clearly this discovery is a game changer. . The NASA Astrophysics Decadal process is just starting. I believe in the past that Gravity Physics wasn’t factored in prior Decadals. Now that we know that this phenomena exists and is measurable, I would imagine that the next step would be for it to become a part of the next Decadal Survey. It will be interesting to see what happens.
LISA was the second ranked flagship mission in the 2010 Decadal, after the Decadal-committee-cobbled-together WFIRST hybrid JDEM/ planet finder.
NASA centers have been explicitly told not to submit gravitational wave missions to the 2020 Decadal – which wouldn’t stop non-NASA researchers, but it’s going to be a hard sell without the cooperation of NASA.
Which may not matter. The last Decadal was DOA, as JWST is sucking all the air out of the room, and continues to do so. Meanwhile, WFIRST costs continue to increase. JDEM was originally proposed to the 2005 mid-Decadal as a $0.5B mission, which was a joke even then, but somehow people said it with a straight face. Accepting the white elephant NRO cast-offs made their costs go up, not down.
LISA will see super-massive – (galaxy center class) BHs, which put out frequencies too low for LIGO to pick up, for one.
Perhaps this can help explain how they are complimentary :
Too bad space based GW community will have to wait to 2034 for ESA Gravity Wave Mission , as there are nothing in the hopper till then ( and i’d expect it not to go in 2034,,probably many years delay to end of that decade)
That’s an impressive result. Others have commented on the significance, and I agree. But they have very good data for a first detection. When I read the press release, I wasn’t sure how clear the signal was or how much processing they had to do to pull it out. After looking through the paper, I’m convinced. I don’t know much about general realitivity, but I’m enough of a data monkey to recognize a clear signal. They have got one, and that is really impressive.
Indeed. And I think they presented more data than I ever expected possible by pin-pointing the spatial location of the event; plus they characterized the event, even calculating the number of players as well as the fraction of mass converted to energy.
Truly stunning. It is a great time to be alive.
Except, maybe, say 100 years hence, when we’ve taken the lessons of GR to interstellar flight 🙂
My mind got a little blown trying to contemplate the energy levels being discussed. The collision of the singularities released 3 Solar Masses of energy in 20 milliseconds. If I can rough the math for you: 2.7 E49 Watts. We don’t have prefixes near that high.
27 septillion yottawatts? (Total solar output: 385 YW)
Mind you, the torsion on spacetime at Earth was only of order 1E-21, but we’re 1 billion LY away (~1E25 m).
Now that we know how much energy it takes to have that “little” of an effect, to actually warp space to do FTL travel is starting to look more daunting. I’m reminded of a line in a book discussing the science of Star Trek contemplating the destructive force of the Enterprise’s antimatter fuel tank: “No wonder Scotty always looks so nervous.”
I was also shocked by the estimated source strength. 3 solar masses converted to energy, in a fraction of a second, is a huge event. I’m more usted to micrograms of matter, which, when converted to energy could destroy a city. Three solar masses? I guess I can understand why that could be seen from one side of the universe to the other.
It is my understanding that the force of gravity follows the inverse square law. Most of the discussions about FTL warp drive talk about warping space only around the spaceship. Right now it’s anybody’s guess as to what size a spaceship would have to be to have a power source and warp field generator powerful enough to go FTL. The LIGO observed event covered a volume of space with a radius of 1.3 billion LY. At this point in time I’m not sure whether this observation tells us very much one way or the other about warp drive. But this observation is a great achievement for the LIGO team.
Indeed. My comment about GW and space travel was a little off the cuff; what I meant to say was that the universe holds so much to be discovered that rejecting anything as impossible, including FTL travel, is a little premature, to say the least.
We aren’t even *close* to an overall sense of just how the universe actually works. Not even close. Current thinking that progress towards this broader understanding lay at the intersection of micro and macro may or may not pan out. Who knows?
Nobody.
By the stories it was whoppingly clear at the time of the event and recognized instantly. A large fraction of the work comprised tedious checks to make sure that they weren’t fooled in some way, such as by the inadvertent or even malicious injection of fake event.
Look at the names and affiliations on that huge author list. Nations doing together what none could do alone. Bravo to the LIGO team.
Yes, they cut it off too early. But — they also successfully streamed it without interruption/pauses with a lot of viewers. The presentations were clear and articulate. Good job by the NSF (except for the premature cutoff).
Keith OFF TOPIC so please delete
http://edition.cnn.com/2016…
might be of interest to your readers 😉
The PRL paper is very well written and easy to grok, even if you aren’t a relativity theorist. Awesome achievement. Were I thirty years younger…
This is great news, but what is sad is that we had to wait months to find out about taxpayers dollars being well spent because of a journal embargo…
https://www.theguardian.com…
Gravitational waves embargo broken by tweeted picture of Nasa celebratory cake
It is also sad this researcher was reportedly reprimanded for breaking it.
The embargo was probably on the order of a week or so, not months. If you look at the submit date vs. the publication date for the Phys Rev Letter, the paper was submitted to PRL Jan 21 and published Feb 11. The LIGO team correctly spent the time from September until then trying to determine whether anything else could have produced the signal – it’s a major claim and you want to get it right (see, for example, the superluminal neutrino observation that turned out to be due to bad clock sync). I heard about it informally about a week before the official announcement, which would be consistent with everybody being careful about it until the paper was accepted.
Thank you for this. This extraordinary claim required extraordinary proof and they took the time to get it right. This ‘taxpayer’ argument is played out. Try to get information out of the DoD for the taxpayer dollars it gets.
Can anyone explain in basic terms what this means…does it have any implications for future space travel..I understand the discovery is a big deal…I just don’t get if it has any practical applications
It has immense practical applications. We now have a completely new window with which to observe black holes, neutron stars, supernovae, and other compact energetic objects in the Universe.
That may take some time. Given the difficulty in simply making one detection, going from a gravity wave detector to a gravity wave telescope may take decades. But it will be extremely cool when we get there.
It’s a GW telescope now! The observation of a binary of 30 Msol BHs is already of high astrophysical interest, and other source detections have already occurred. The longer LIGO runs, the more goodies we’re going to get.
How, exactly, do they determine the direction of the source? That’s something I expect from a telescope rather than a detector. With two sites, and propagation at the speed of light, you can get one angle. You might estimate the other from polarization and theory, but I’m not sure I’d call that a measurement.
Direction is only one part of what you get from the data set – there are several other parameters of astrophysical interest that you recover from an event as well. In the case of the 9/14/15 event you get the mass of the progenitor BHs, the merged BH (and mass deficit), spin of the final BH, distance, as well as others. The observation of two bound 30 Msol BHs is already extremely interesting. These are all measurements.
In any case, two stations give you a circle on the sky at the minimum – in this case it was further reduced an arc. Add another station or two, which will happen in a year or two, and you’ll do much better.
Just to be pedantic, you are describing something much closer to a spectrometer than a telescope. But it’s still a fine instrument.
Huh? Large ground-based telescopes spend most of their observing time doing spectroscopy, and it is a large component of what HST and other space-based telescopes do.
Sure. But telescopes have angular resolution. That’s inherent to the nature of the instrument. They also can provide information of the nature of the waves they see, and that’s often the most interesting part. But the optics and design is about getting angular resolution. Perhaps I should have said LIGO is more like a.seismograph, not a spectrometer. My point was that the design is, first and foremost, about measuring the amplitude, phase and other properties of the waves, not their direction. Direction is more of a side effect. Something they get for free, as part of using two sites for coincident noise rejection. I’m not criticizing that. I’m just being a little picky about exactly what sort of excellent observatory they have.
I’m afraid that I don’t understand the focus on semantics here. As an observational astronomer, I consider any device that provides observational information on a distant astronomical source to be a telescope. There is no value in calling LIGO something else.
NASA won’t be observing black holes with a NASA led Gravity Wave mission till the 2040’s, if then. ESA’s L3 mission, LISA, is schedule for a 2034 launch. NASA is contributing some $ to that. There is nothing between now and then.
Go LIGO!
If memory serves, NASA almost killed the LISA mission, by promising to contribute and then changing their minds. That was around the same time as the ExoMars and EJSM messes. We really did not win points for being a reliable partner.
NASA did kill their participation on the joint NASA/ESA LISA mission, which was an approximate 50/50 partnership. ESA decided post breakup with NASA to go it alone w a GW mission, and it is referred to as LISA, again. ESA has penciled in a 2034 launch date. ESA is allowing NASA to contribute some monies to this, but it is not a 50/50 amount…more like 5%
Apparently this required a laser interferometer which could detect a displacement of 10E-18 meters (a thousandth the diameter of a proton) in the length of a 4km tunnel. Naturally the detectors pick up earthquakes, trees falling in the forest, etc. so at least two detectors are needed to distinguish gravity waves (travelling at lightspeed) from the mundane vibrations of Earth (travelling at soundspeed). Then they had to listen patiently for ten years before they heard something.
Most of that ten years was before LIGO sensitivity was upgraded to the necessary threshold. Rumor has it that there are additional detections since then yet to be announced.
One wonders just how frequently the universe changes 3 solar masses into energy.