There were rumors afoot yesterday that this would be announced today. And my CNN news feed just directed me to their article, which I reproduce in its entirety; the headline calls gravitational waves “the holy grail of modern physics.”
Gravitational waves are a reality, according to scientists from an institution that has been hoping to observe them.
“We have detected gravitational waves. We did it,” said David Reitze, executive director of LIGO, the Laser Interferometer Gravitational-Wave Observatory.
The discovery, based on ripples in space-time detected by LIGO, supports a prediction made by Albert Einstein that’s essential to his general theory of relativity. The ripples LIGO detected are based on the merging of two black holes, Reitze said.
“What’s really exciting is what comes next,” he said. “I think we’re opening a window on the universe — a window of gravitational wave astronomy.”
LIGO is described in a statement as “two identical detectors carefully constructed to detect incredibly tiny vibrations from passing gravitational waves,” one located in Louisiana, the other in Washington State. The project was created by scientists from Caltech and MIT and funded by the National Science Foundation.
Szabolcs Marka, a physics professor at Columbia University, told CNN that “we will be able to study not just Einstein’s general relativity — we’ll be able to find objects we only imagined would exist. We should see a universe that has never been observed before.”
Marka said to think of it as a “cosmic microphone,” an incredibly precise listening device that can detect distortions in space-time, the fabric of the universe. It’s so precise it can detect changes the size of a soccer ball in the entire Milky Way galaxy.
The discovery of gravitational waves is like opening another of our senses, Marka told CNN’s Rachel Crane: hearing the universe as well as seeing it.
“And when we hear the universe, we will learn about the secret life of black holes — their birth, their death, their marriage, their feeding. We will hear when a black hole eats a neutron star,” Marka said. “Nobody has ‘seen’ that before. We will not only understand it, we will ‘see’ it. It’s the most fascinating thing I can imagine.”
Indeed, black holes are a holy grail of the gravitational wave concept. To date, we’ve been able only to see their aftereffects — black holes themselves remain a conjecture. Discovery of gravitational waves would confirm their existence.
“It’s the first time the universe has spoken to us through gravitational waves,” said Reitze. “Up to now we’ve been deaf to them.”
You can read the Wikipedia article on gravitational waves, or, better yet, the very nice piece in the Torygraph by Martin Rees explaining the significance of this detection, which he calls “one of the great discoveries of the decade”. The apparatus for detecting the waves is amazing (my emphasis):
In the LIGO detectors (the acronym stands for Laser Interferometer Gravitational-wave Observatory) intense laser beams are projected along 4-kilometre long tubes, from which air has been evacuated.
By analysing the light reflected off mirrors at each end it’s possible to detect tiny changes in the distance between the mirrors. When a gravitational wave passes, the distance between LIGO’s mirrors alternately increases and decreases as “space” expands and contracts.
This is an immensely delicate experiment: the effect being sought is so tiny that it “shakes” the mirrors through a distance less than a millionth of the size of a single atom. This is why it’s been crucial to have two similar detectors separated by nearly 2,000 miles – one in Washington State, the other in Louisiana – and to seek events that show up in both detectors, thereby ruling out effects caused by local seismic events, passing trucks, and so forth.
The collision of the two black holes that produced these waves happened a billion years ago. That, combined with our ability to detect movements of a mirror a mere millionth the size of a single atom (through light interference) is truly a stunning thing. What other animal could not only predict such waves, but then wrest materials out of our Earth to make a device that finds them? And I’m not even mentioning that we also found out about black holes.
One of the two detectors:
Rees is not 100% convinced that the discovery is genuine, but seems to accept it as pretty sound. And, if real, it’s a Nobel Prize for sure.
Fascinating to watch the live feed from the announcement. The numbers are incredible!
Fabulous news… So interesting!
Pretty sure those waves were placed there in situ 6,000 years ago. To test our faith.
Oh, no; to enable us to discover God!
https://lovegod.wordpress.com/2007/02/19/god-could-be-detected-by-gravitational-waves/
No scientific discovery will ever be enough to destroy the faith of believers, nor prove impervious to attempts to twist it so that it actually SUPPORTS their beliefs.
Wow. I mean, just, wow. I’m tempted to call Poe, but I think it is sincere.
Sweet baby jesus on a pogo stick. Did you read the comments? The author replies to the first comment, with an utterly ironic lack of self-awareness, “I’m not entirely sure what you mean.”
And Anirudh clearly has issues.
Oh dear.
It’s (probably) religion, but not as we know it.
“All directions that we can see with our eyes are in the braneworld, but God may be in the direction that is invisible to us.” I don’t even want to try to think what that could possibly mean.
cr
Actually, it happened 1.4 billion years ago, plus-minus 20% !
If you add up all the genealogies of the Old Testament you will find that it WAS about 6,000 years ago, as stated. Maybe you should just check your calculations!
Quite apart from the physics, there’s another reason to be pleased: Sean Carroll says, “Applause for the fact that the #LIGO paper was peer-reviewed before the press conference was called.”
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Ohhh, take THAT, Pons, Fleischmann … the Messel Shale “first primate” … and an annoying litany of other examples of press conference publication.
Lawrence Krause has been tweeting hints of this since just before the holiday season – and getting some rather miffed comments for it. Yes, it has been delicious anticipation, but FFS, give us the paper!
I think the particular target of Carroll’s remark is BICEP2.
Will ordinary surfboards work?
The gawds just took another major hit.
Oh, this is not going to go down well with the Jim Bakker/Brian Fisher crowd. As soon as they get winds of the implications their knotted panties may actually strangle them.
‘Tis no doubt the mere flapping of angel wings. Or perhaps Satan taking delivery of eighteen hundred thousand billion quintillions of kazarks of brimstone…
With apologies to Capt Stormfield.
See my post above. They’re ahead of us!
Oh, no. The Jim Bakker/Bryan Fischer crowd would condemn the author of that blog as having gotten far too much in bed with science. The typical member of the JB/BF crowd is the ignoramus’ ignoramus.
“Rees is not 100% convinced that the discovery is genuine, but seems to accept it as pretty sound.”
And how are they going to verify it? No one else has a gravity wave detector of equivalent capability.
The same way they do any large one-off experiments; allow other scientists to comb through the raw data and do their own independent data analysis, to see if the signals observed can be better explained by some other phenomena (i.e. interference). If they wanted to be really sure, they could also allow independent groups to also take a look at the hardware – IIRC, the ‘faster than light’ result from a few years back turned out to be hardware problem – but I doubt in this case that anyone will demand that level of check. Instead, to see if it’s real, they’ll run the experiment again and again. After all, its not like the binary system is going anywhere…
FTL suggestions are taken quite lightly. GW, on the other hand, are a very robust solution for General Relativity. LIGO should work and it would work a lot more persuasively if there happen to be binary collisions occurring just off our doorstep (<10k lyrs) about once a year. We live in a quiet neighborhood, hence the many years of waiting.
Gravity waves are to bird watching.
As faster than light is to cold fusion.
During the Q&A portion of the live webcast of the announcement, a Japanese journalist brought up the current construction of the Japanese Kamioka Gravitational Wave Detector, and one of the scientists said that this one has some superior technology and features, such as cryogenically cooled mirrors to minimize vibrations, better environment away from interference, etc.
https://en.wikipedia.org/wiki/KAGRA
It could be ready maybe 2018/2019.
There’s also VIRGO in Italy that’s had an update and will be running again this year.
THAT set of waves id “tatties ower tha side.” But where there is one, there will be more.
The Italian “Virgo” detector is a couple of years into (half-way? -ish?) a series of upgrades similar to what LIGO went through to become the AdvancedLIGO which actually made the discovery.
Of course, a critical part of the detection is that not only did both the Hanford and Louisiana detectors detect a signal, but that the profiles of the signals matched very closely in time. The very design of the instrument has it’s own verification built in.
Every gravity wave detector with the possible exception of the very first design in the 1960s has used this design of having two “identical” detectors on separate sites. For exactly the reason you give.
Reitze has said to media [too many tabs open error – gravity makes waves (O.o)] that they have some 4 or more mergers in the full first run. The paper was on the first, strong one.
So there are good hopes the VIRGO detector will make an independent verification before year’s end. (They claim that when advLIGO is finished, they will see ~ 1000 mergers/year.)
Another 12 papers will be going up shortly, I’ve read. Perhaps one will have information on the other detections.
There are 10 additional papers up. List including arxiv links at the bottom of this page:
https://www.lsc-group.phys.uwm.edu/ppcomm/Papers.html
The Astronomy Picture of the Day (APoD) has an illustration depicting this discovery.
This leads me to wonder if we are on the edge of understanding gravity to the same extent that we began to grasp the connection between electricity and magnetism almost two hundred years ago. The ability to control and produce magnetism at will is the foundation of all of our electronic technology and contributes significantly to mechanical technology as well. Imagine the possibilities if we could learn to produce gravity fields as easily as we can now produce magnetic fields. I doubt whether the early experimenters in magnetism could have forseen what their work would lead to. Who knows what we will be able to do if we can learn to manipulate gravity?
It is my (very low confidence) understanding that it is not possible to manipulate gravity short of moving mass (or the ludicrous energy equivalent).
If such things were in any way implied by this discovery, I should think the press release would have mentioned it.
Can somebody with actual knowledge of physics comment on this?
I would say you are generally correct. For protons and electrons, gravity is something like 30-40 orders of magnitude weaker than the EM force. Technologically that translates into “building devices where charge is moved around to produce highly complex phenomena – easy. Building devices where gravitational forces are shifted around to produce highly complex phenomena – impossible.”
That would not be me, but I’m gonna say something anyway. I suppose that application of this principle would allow us to develop super duper precise clocks by correcting for the tiny distortions in space-time caused by passing gravity waves.
But I doubt that we could really manipulate gravity to give a dramatic effect. We would have to manipulate vary massive things, like stars, to produce a measurable effect in gravity.
In fact, if Einstein is right one more time, magnetic fields can distort spacetime. There is a proposal for an experiment that makes sense, and interestingly, you would need an instrument like LIGO to demonstrate this.
Einstein’s theory of general relativity predicts that a magnetic field
causes a curvature of spacetime as well. To test this, Füzfa, a physics in Belgium proposes
to modify an existing laser interferometer gravitational wave detector,
such as LIGO, by adding superconducting magnet coils in one of the arms
of the interferometer, and bouncing a light ray back and forth through
them. By each passage the phase shifts because of the extra curvature of
space (which is tiny) caused by the magnetic field. By bouncing this
light for 200 days, the total phase shift will come within the
sensitivity of the interferometer.
http://www.alphagalileo.org/ViewItem.aspx?ItemId=159844&CultureCode=en
“Einstein’s theory of general relativity predicts that a magnetic field
causes a curvature of spacetime as well.”
Not directly though, but by its energy content as everything else. That is the current accepted semiclassical everyday physics (outside black holes) approximation where quantum field theories lives on a background of general relativity.
The referenced paper propose a theory along the lines of Einstein’s failed extended theory. It treats classical EM & GR on the same footing. But that isn’t GR proper, it isn’t QED proper, and similar theories – Einstein’s – failed.
I understand one can change the internal stresses of a body, which is movement of another sort. (Apparently this is what would in principle allow gravitational repulsion.)
I am not a physicist, though.
Nothing in GR allows gravitational repulsion I think. It is shown by quantizing it – the only charge, the graviton, is positive (has mass).
There are cosmological solutions that set up a negative pressure (dark energy, likely the effect of the vacuum with its particle fields), FWIW. So maybe you can manipulate that, and yes, manipulating the stress-energy tensor would be similar to manipulating the stresses of a body if I understand correctly. [ https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor ; have not studied GR.)
Oops, negative pressure is still acting attractive. So I need to understand GR in order to see if we can derive a solution that isn’t inherent in the type of force (attractive).
The reason that one can manipulate electricity and magnetism is that electro-magentism is a rather strong force, but one that normally cancels owing to equal numbers of positive and negative (or north and south) charges. Thus manipulating those charges gives potential for useful things.
Gravity, in contrast, is a very weak force, and it only ever adds (there is no negative-gravity “charge”). Therefore the only way to do much with it is to accumulate large amounts of mass.
Any thing that has mass will affect gravity (trivially true). However, manipulating EM fields is easy. And even if we could manipulate gravitational fields, they are about 1/10^40 times weaker than EM fields, hence collided astronomical objects are needed usually to make such disturbances.
Having grown up with visions of a Star Trek universe, I’m jointly discouraged by our primitive technology and astounded by what we can actually discover using it.
+1!
Are we any nearer to a tractor beam?
Yes. They can move paper clips and dead flies.
That’ll do for a patent.
STEM types get the patents, but the MBA/JD types get the money, eh?
I considered adding that, but I’m not sure if it has been patented. It is, I believe, under development for micromanipulators for use in single-cell treatments.
There are laser traps (microparticles, molecules, atoms, and ions). There are acoustic traps for small solids and liquids and there are magnetic traps for just about anything paramagnetic (which is just about everything).
But an EM or gravitational tractor beam in space. You might want to wait for real light sabers too.
All because of SCIENCE!!
My rough calculations say that it’s 10-100 millionth of the size of an atom, not one millionth. Even more spectacular a discovery.
Yeah, that’s about right. One thousandth of the diameter of a PROTON, not (as many of the news outlets have got it wrong) “one thousandth of the diameter of a hydrogen atom”.
I have several questions on this and submitted them to Ethan Siegel. (No disrespect to Sean Carroll, for whom I have no contact information.)
Do the waves weaken with distance? Do they “red shift” due to expansion of the universe? Could this be a way that information leaves a black hole? How do they determine the origin of the waves? Is there a “CMB” or, in this case, a CGWB” for the waves?
You could leave a comment on Sean Carroll’s blog.
A first stab at your questions would be:
“Do the waves weaken with distance? Do they “red shift” due to expansion of the universe?”
Yes and yes.
“How do they determine the origin of the waves?”
By modelling the signal to deduce what event must have caused it.
“Is there a “CMB” or, in this case, a CGWB” for the waves?”
Yes, there would be gravitational waves left over from the Big Bang, creating a “background” signal. I think these would be pretty tiny though.
I think that gravity waves from the big bang were claimed over a year ago, then that claim was walked back. I think people are still cleaning up the data to look for them again.
What they were looking at a year ago we’re not actually gravity waves. I would think that the Big Bang would have put a tremendous amount of energy into gravity waves and it might not be insignificant at this point.
Correct!! The gravity waves from the BB would have move on. That seems obvious to me now.
Not quite. What that claim was about is the effect of gravitational waves imprinted on the CMB.
Thus the gravitational waves from the inflationary era affect the early universe, which affects the CMB, which we can then observe.
Those same gravitational waves will still be travelling around the universe (vastly weakened), but it was not a claimed detection directly of those waves.
Was that the BICEP results? Structure in the cosmic microwave background which were initially thought to result from gravity waves in the CMB-era Universe, but were later shown to be contamination from the distribution of galactic dust.
Yes, although they are gravitATIONAL waves. Gravity waves are a different thing. Sorry for the pedantry!
I am sure many people are getting that lesson today from Wikipedia.
More precisely, it was shown that at least half and perhaps everything of the signal was dust. So there was no significant signal anymore.
My answers are the same as Coel’s. I read the PRL yesterday and it was fantastic, if you can get a copy it is an excellent read:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102
If you want to ask him questions, Sean Carroll’s public web site is here. I’m no expert but I believe I can answer some of your questions.
Do the waves weaken with distance?
Well the gravity from the source weakens with distance, but I don’t know what that implies for the relative “trough” and “hill” height of the waves.
Do they “red shift” due to expansion of the universe?
Don’t know. Now I’m 0 for 2. 🙂
Could this be a way that information leaves a black hole?
AIUI no. The information paradox is because infalling matter and energy has structure, while outgoing QM radiation and the BH’s gravity does not.
How do they determine the origin of the waves?
They take on-axis and off-axis measurements and subtract. 🙂 Its a lot more complex than that, with a lot more noise reduction being done, but I believe that’s the 40,000-foot description: they take measurements at different times and orientations (of the Earth; the equipment doesn’t move, but the Earth spins in relation to celestial targets), and they analyze the different signals they get to figure out which ones are coming from a specific point in the sky.
Is there a “CMB” or, in this case, a CGWB” for the waves?
AIUI most of the standard flavors of inflation and big bang theory predict there should be a CGWB, but we haven’t found it yet.
The problem is analogous to that of determining the location of an earthquake from the arrival times at multiple seismographs. With one station, you only get the approximate distance (there is dispersion between different parts of seismic waves that travel at different speeds, so their spacing gives you the distance ; here the acceleration of the inspiral gives you the mass of the interacting objects, and therefore the original signal strength while the strength of the received signal then gives you the range (inverse square law). The strengths of the signals on the two legs of each detector will give some indication of the source direction – which is part of the reason for the wide spacing, so that the curvature of the Earth introduces some out-of-plane measurement. I don’t know the angular accuracy – it should be in the paper. But it’s unlikely to be better than a few 10s of degrees – which was what Super Kamiokande had when it detected SN1987A.
I’ll have to go and find TFP now, won’t I?
The likely signal location was shown as a long elliptic strip.
With VIRGO online they can triangulate, and with the Japanese detector 2018-19 they would remove a degeneracy of such a triangulation setup (and add resolution, I guess).
Ah, there was video? I was trying to log into the webcast version, but just wasn’t getting a connection. The “live broadcast on the telly left out the “sciencey bits”.
“Could this be a way that information leaves a black hole?”
Hawking has a video on BBC where he claims that:
a) the model of the merger tests his area theorem, the area of the resulting BH is larger than the sum of the pre-merger BHs.
b) the observation is consistent with the no-hair theorem, where precisely the mass and spin (and charge) of the BH is the only known info.
But are you perhaps thinking of Hawking et al’s latest paper where they claim information leaving? IIRC it uses “no-hair hairs” or weak ones, the idea is that the ground state of the vacuum has a degeneracy. I.e. it has several configurations with the same energy, where somehow information leaks from the event horizon as energy (Hawking radiation) does.
If you wonder how a vacuum degeneracy can look like, I think Sean Carrol et al’s latest paper may demonstrate that. (But that is my interpretation of it.) They looked at “entropic gravity” and saw that proposing quantum entanglement of the vacuum could be a base to extract GR equations. And that set up looked like it had several config’s for the same energy, unless I am mistaken. (Sounds spooky, but the little physics of the paper I grokked looked good to me.)
Sean Carroll.
This is truly wondrous. New waves rock us ever so gently when black holes collide, ‘tho the waves do take a bit of time to arrive.
Science rocks!
This is a huge new scientific field that be studied during your lifetimes.
Sent from my iPad
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There are several other LIGO-type (interferometer) detectors on-line now (e.g. Virgo, in Pisa) – I wonder if they saw the same signals?
And there are more advanced ones, with even better sensitivity, coming in the next few years: Advanced Virgo, KAGRA in Japan, etc.
I think we can expect an interesting next few years in this field!
I wonder if we could make a big array of detectors to start making images of passing gravity waves that extend out over space from their sources. Right now the images are linear traces from point sources.
Lesseee … working the geometry. To get maximal directional information, you’d need 4-off LIGOs arranged as closely as you can get to the vertices of a tetrahedron. Which would mean one each in South Africa and South Australia, one in aroundabout the Yamal region of Russia. And the original Hanford LIGO for the first.
I didn’t notice the cost of a LIGO. But double it.
Virgo is in pieces on the kitchen table, in the process of being rebuilt into Advanced Virgo.
Virgo non intacta?
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+1
Fantastic, well done LIGO.
sub
Well done scientists! I’ve heard many scientists already say that this is just the beginning. It will be so exciting to find out what science will discover with this tool in the next decade.
Well done! Another annotation for the old books I have 😉
[youtube https://www.youtube.com/watch?v=FXlg3cr-q44&w=755&h=425%5D
That’s a very good explanation – even I can understand it.
+1 to that.
By the way, I seem to recall that, when lasers were first invented, they were described as ‘an invention looking for an application’. Well….
cr
You mean the interferometer (what LIGO is). That instrument, invented in the 19th century caused in part the relativity revolution when Michelson and Morley could not prove the existence of an aether, using a similar instrument (but it fitted on a table).
No, I meant lasers. Which LIGO uses.
I know what an interferometer is, but Mitchelson & Morley didn’t use (or need) laser light.
But I doubt whether LIGO could work to the incredible precision it does without a coherent (i.e. laser) light source.
I was just reflecting on the current ubiquity of lasers, compared with how exotic they seemed when first invented. Now available as cat toys. We take it for granted that LIGO would use a laser – what else would it use?
cr
You mean this miniscule little wave is more important than rock light shows?
Well, no. Nothing outranks Pink Floyd.
Unless those black holes chose to collide in our vicinity, then they might 😉
cr
Glad you have your priorities straight. 😉
Good description. I’ll share this one with my friends.
Wow, I’m duly impressed. Especially with little interest/experience in the actual overall subject matter. But, I will admit the diligence behind this effort is heroic. I may just take a little time to observe some of these events as they unfold….
Sean Carol comments on his post adding this discovery to Higgs on the list of the big set of discoveries that he thinks will come in the decade of the 2010s:
1 Discover the Higgs boson.
2 Directly detect gravitational waves.
3 Directly observe dark matter.
4 Find evidence of inflation (e.g. tensor modes) in the CMB.
5 Discover a particle not in the Standard Model.
http://www.preposterousuniverse.com/blog/2016/02/11/gravitational-waves-at-last/
Sean Carroll.
It’s like science fiction. So many questions I am hardly qualified to ask like: if these have never been detected, and the detector is super sensitive, how do they know what they’ve detected are gravity waves?
The detection of gravitational waves is based on computed models of what the signal should look like, a specific pattern that can be distilled out of the background noise. It is like identifying a human voice standing near a waterfall. If certain patterns in the noisy signal coincide with what would have been produced by an event, such as the collision of black holes, or, if the source is nearby, a supernova, then you have a likely hit.
The existence of gravity waves and their properties were proved in 1993 (or was that when the Nobel was doled out?) from observations of a pair of co-orbiting pulsars. That in itself speaks of a star system that would have been interesting to be a neighbour of. Not a close neighbour though.
The pulsars were losing orbital energy and changing their orbital frequency in a way which accurately matched models of gravity wave radiation from the system. In about 300 million years, this system too will go “splat.” Bring popcorn.
I’ll add to what gravelinspector says that special relativity shows that you have to have gravity waves. The absence of “[immediate] action at a distance” means something has to carry interactions. (It is more details, but that is the gist.)
How the universe really works!
Congratulations to the scientist,
“Winkler and Rüdiger say they’re happy that LIGO has now vindicated their life’s work. They’re also happy for their mentor, Billings, who is now nearly 102”
and of course, Mr Einstein.
Almost as big a “miracle” as all the science and technology that went into this is the fact that they managed to secure funding for this project. The public has a very split personality about science.
Copy of the paper (which will appear in PRL) is here:
https://dcc.ligo.org/public/0122/P150914/014/LIGO-P150914%3ADetection_of_GW150914.pdf
The APS server was down for a while; they tweeted it was getting 10,000 hits per second!
Excuse me, per minute.
About a thousand co-authors, and three of them did not live to witness the publication.
There are 133 *institutional affiliations* involved. Wow.
Another benefit of the WW II Manhattan Project. The GW observatory at Hanford is exceptionally quiet — a huge landscape with no road traffic, tractors, industry thanks to wartime sloppiness with radionucleides.
Also one of the most important bioreserves in North America. It would be orchards and wheatfields today without the contamination.
It is truly astonishing what can be done with legos.
😀
One can build a Michelson Interferometer with legos!
http://www.instructables.com/id/Michelson-Interferometer-build-from-LEGOR-bricks/
Amazing discovery, but I was even more amazed by the amount of details they extracted, from the merger to the probing of strong gravity. I.e. the strength approaches 1 in normalized units.
[Strictly speaking astronomers have seen a BH event horizon a few months back, when they resolved clumps of merging gas those death screams were a) cut short and b) not ended with thermal radiation from being plastered on a star surface. So they weren’t first on exotic gravity, or more or less unambiguously testing the existence of black holes.]
Also, Hawking has claimed that the model result has his area theorem on BH tested and passed. (I gave details in another comment here, but see BBC for his video interview.) Exotic physics!
This article, written by Krauss, is pure poetry and emphasizes just how staggering these findings are. Beautifully penned.
http://www.nytimes.com/2016/02/14/opinion/sunday/finding-beauty-in-the-darkness.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-left-region®ion=opinion-c-col-left-region&WT.nav=opinion-c-col-left-region&_r=0
Here is a nice primer on gravitational waves and this experiment from the Perimeter Institute:https://www.perimeterinstitute.ca/news/gravitational-waves-101
Great link, thanks for that!
I can hardly wait to assemble a Lego Ligo.
The best version of prophecy I can think of!
What gravitational waves sound like:
http://gizmodo.com/this-is-what-gravitational-waves-sound-like-1758501755
xkcd has noticed the event:
http://imgs.xkcd.com/comics/gravitational_waves.png
cr
He immediately picked up on the significance.
I think we tend to take things like this too calmly as though its just an everyday occurence, It blows my mind that an event occured 1.3 Billion Years ago that we can now listen to, a little beep every second or so, proof of the Genius of one Man who predicted their effect, its incredible but what it means for us ?,I don’t know ,I’ll leave that to the Theoretical Physicists and Astronomers.lol
There’s an excellent article on what those result mean (and also what they don’t mean) on a blog by Theoretical Physicist Matt Strassler called “Of Particular Significance”. Here’s a link:
http://profmattstrassler.com/2016/02/11/advance-thoughts-on-ligo/
He wrote it before the actual announcement was made – hence the title – but what was announced was obviously expected. It’s a good and even exciting read – like for instance when he describes what kind of event it must have been that sent out the measured gravitational waves: Black Holes of a dozen or so Sun masses circling each other about a hundred times per second before they crashed.
Anyway, this paragraph sums it up nicely:
So it’s really not the gravitational waves themselves that we should celebrate, although I suspect that’s what the press will focus on. Scientists already knew that these waves exist, just as they were aware of the existence of atoms, neutrinos, and top quarks long before these objects were directly observed. The historic aspects of today’s announcement would be in the successful operation of Advanced LIGO, in its new way of “seeing” the universe that allows us to observe two black holes becoming one, and in the ability of Einstein’s gravitational equations to predict the complexities of such an astronomical convulsion.
I see that a number of people have referred to “gravity waves” as though they were the same as “gravitational waves”. What LIGO detects are gravitational waves, *NOT* gravity waves.
Gravity waves are waves caused by gravity, like ripples in a pond when a pebble is dropped into the water. Likewise, ripples occur in the atmosphere when the wind blows over a mountain range, and these are also examples of gravity waves.
In contrast, gravitational waves are ripples in space-time caused by varying gravitation. If you could stand at a fixed point in space and a planet passed by you there would be exceedingly weak gravitational waves passing through you. If a star passed by the gravitational waves would have a larger amplitude, and so on up to and including a black hole passing by.
Two neutron stars or black holes (or one of each) co-orbiting near each other cause *huge* ripples in space-time and it is this radiation of energy that causes the co-orbiting bodies to spiral in towards each other. This radiated energy is what LIGO detects. The approximate amount of energy radiated by the detected gravitational waves stated is equivalent to converting the entire mass of 3 times our sun into energy. Do not confuse this with the amount of energy that the sun generates through fusion. In other words, combine the mass of 3 suns with an equivalent amount of antimatter to get the gravitational energy radiated. Matter annihilation of hydrogen produces about 100 times as much energy as fusion.
Similarly the planets in the solar system orbiting the sun cause ripples in space time but these ripples are minuscule compared to co-orbiting multiple stellar sized masses.
Improvements in the sensitivity of LIGO detectors should eventually make orbiting planet detection possible in the future.