Just a quick note here as I’m on deadline for a piece on this stuff, but today we got the official announcement of the worst kept secret in physics. Here, via the Guardian, is the TL:DR version of what was said:
On 14 September 2015 at 9:50 GMT, the two detectors of the newly upgraded Laser Interferometer Gravitational Wave Observatory (LIGO) detected a signal.
It was unambiguously a gravitational wave signal because it matched the predictions from Einstein’s general theory of relativity almost precisely.
This is huge news, as it is, among other things, the latest and most elusive (so far) direct confirmation of Einstein’s General Theory of Relativity, a theory of gravity that describes what we feel as a force holding our feet to the floor is in fact the local warping of spacetime by matterenergy. (In the case of our feet and our floor — that warping is the dent in spacetime created by the mass of the earth.)
It is as well a triumph of virtuosity in observation and measurement. The detection of a gravity wave is a simply wondrous an act of human hands and mind. It is a joy to witness, at least for me.
More after I get the paying work done….
Update: As noted by commenter Michael Bersin, you can think about gravity waves as acoustic ones — sound. As it happens, a couple of my students in a course I teach on making science documentaries are all over this. Check out Sasha Chapman’s and Allan Adams’ audio piece over at The Atlantic’s joint in which MIT physicist Scott Hughes sings the crash of black holes.
Image: J. W. M. Turner Storm at Sea 1851 or before.
Betty Cracker
I’m far too dumb to understand it, but yay gravity!
Brachiator
As I noted elsewhere, icing on the cake would be confirmation of the Silver Surfer riding on these gravitational waves.
But great news! How certain is the confirmation of gravitational waves? Is there a chance that this discovery could be walked back?
You can field questions about this discovery to Dr. Amber Stuver of the LIGO Livingston Observatory in Louisiana via Gizmodo.
I wonder if this will be good enough for a question about the importance of the advancement of science in any of the upcoming presidential primary debates?
dmsilev
@Brachiator: It’s a pretty definite signature. One reason why this was, as Tom said, a very poorly kept secret is that they spent the last three or so months working on the data and eliminating as many alternate explanations as possible. Nothing is ever a sure thing, but the team did their due diligence.
Cermet
The results are well above five sigma – the gold standard – so the results are conclusive. They even know the masses of the original two black holes and when this occurred (about 1.6 billion years ago.) The size of the signal is so small that if the detector was the size of the earth, the gravity wave would lengthen and contract the apparatus all of the length of an atomic nucleus – that is tiny, period.
There will be no walk back since both LEGO’s got the clear signal and as dmsilev said, they cross checked and triple checked and even proved the signal wasn’t a fake one added to their data.
So gravity really is the curvature of space-time; may still be quantized but is a function of space
Brachiator
Also, too, this has really been a great few weeks in science. You can listen to an imminently understandable public lecture by Stephen Hawking on black holes, complete with some cool illustrations:
Watch Stephen Hawking’s BBC Lectures on Black Holes with Chalkboard Illustrations, “Do Black Holes Have No Hair?” and “Black Holes Ain’t as Black as They Are Painted”
Mustang Bobby
I’m reminded of the lines from Close Encounters of the Third Kind when two scientists are marveling at the people returning to Earth after having been away thirty years and haven’t aged because of traveling at near light speed in the alien ship:
SCIENTIST 1: They haven’t aged a day! Einstein was right.
SCIENTIST 2: Einstein was probably one o’ them.
canuckistani
Very cool. An amazing bit of technology used for the detection too!
Mike J
What Iove about the Brits is how understated they are.
Irony Abounds
“a theory of gravity that describes what we feel as a force holding our feet to the floor is in fact the local warping of spacetime by matterenergy. (In the case of our feet and our floor — that warping is the dent in spacetime created by the mass of the earth.)”
Perhaps when you get back you can explain WTF that means, cause I have no clue.
PaulW
what are the practical applications to this? can this be used to design an artificial gravity system for space travel?
C.V. Danes
The thought of two objects, each many times more massive than the sun, circling each other 250 times per second just boggles the mind.
Mustang Bobby
So when my glasses fall out of my pocket and disappear under my desk, it’s the warping of spacetime?
@Irony Abounds:
To quote noted physicist Dr. Sheldon Cooper, “Gravity, thou art a heartless bitch.”
Mike J
@Irony Abounds: I haven’t had to pull out the bowling bowl and rubber sheet since that dirty weekend in Milwaukee.
Einstein said gravity isn’t really an outside force, it is space itself being warped by the mass of objects. If you think of space(+time) as a trampoline, and a planet or star as a bowling ball, you can see how space would deform in areas that had a large mass sitting on it.
singfoom
@PaulW: If I understand it and I certainly do not, I think this is the VERY VERY first step to figuring out how to make repulsors / anti-gravity devices.
Maybe someone more versed in this field can tell me how full of shit I am on that.
MattF
@Brachiator: You might want to just look at the data shown at the Astronomy Picture of the Day site. It shows the data from Oregon and Louisiana superposed. They’re basically identical. You can then add a third curve showing the theoretical prediction– it overlays the two data tracks. Not much chance that this is just an accident.
C.V. Danes
@Cermet: This is without doubt an astonishing achievement, but it also makes me realize that, as far as galactic civilization goes, we are still just babies, barely beyond using smoke signals.
Punchy
The next step is for the WV legy to ban gravitational waves in their state, as these waves are likely to be gay and certainly offensive to the Morgantown chapter of the Southern Evangelical Baptist Church of Inbreds and White Nationalists.
Thoroughly Pizzled
This is awesome news!
Tom, I loved your new book. This must seem like a very nicely timed discovery.
David Fud
I love this stuff. It makes me wonder if the statistical nature of some chemical reactions and quantum events have something to do with spacetime stretching and flexing while particles do their dance. It seems to me there has to be something practical coming out of the fact that spacetime is a bit more flexible than Newton thought.
Michael Bersin
So, apparently gravity waves are music of the spheres (from The New Yorker):
“…As it happens, the particular frequencies of the waves that LIGO can detect fall within the range of human hearing, between about thirty-five and two hundred and fifty hertz. The chirp was much too quiet to hear by the time it reached Earth, and LIGO was capable of capturing only two-tenths of a second of the black holes’ multibillion-year merger, but with some minimal audio processing the event sounds like a glissando. “Use the back of your fingers, the nails, and just run them along the piano from the lowest A up to middle C, and you’ve got the whole signal,” Weiss said….”
shomi
As if anyone here is going to understand any of this.
You have people like mistermix with his hilariously inaccurate political predictions. Cole with his childishly simplistic views being sucked in by every snake oil salesman grifter politician that comes along. Nobody here can do a day without posting about the lastest stupid thing Trump said to get attention.
So you think any talk about Ensteins theories is going to get you more than a blank Idiocracy stare?
Anoniminous
@PaulW:
Let me put it this way, we’re still working out the full implications of Maxwell’s Equations published in 1861 and 1862. As of 2/11/2016 there are no practical applications but that doesn’t mean there won’t be in 2/11/2116.
Mustang Bobby
@shomi: Well, you told us. Feel better now?
C.V. Danes
@Anoniminous: I have a feeling that by 2116 we will be far more preoccupied by mass migrations of the earth’s population, but perhaps by 3116, after we make it through the next Dark Ages and Enlightenment.
Cermet
@PaulW: No
schrodinger's cat
After 100 years gravity waved back!
Paul in KY
@Brachiator: Maybe we can snag a visit by Galactus!
Amir Khalid
@shomi:
Some of us do understand it, at least on a layman’s level, and a physicist like dmsilev understands it on a professional level.
Paul in KY
@PaulW: You can, if you have enough mass ;-)
Cermet
@David Fud: Again, no. Chemistry is far, far removed from gravity waves; even all nuclear events. Proof that General Relativity is correct means anti-gravity is impossible and faster than light speed is impossible (please ignore when negative energy is used so space can be warped allowing what appears to be faster than light travel (it is but isn’t …long story. Google is your friend.))
Paul in KY
@singfoom: I know hardly anything about this, but I think this makes it harder or that it just can’t be done (without having your own huge amount of mass).
Anoniminous
@C.V. Danes:
In either case, faster than a blink of an eye in geologic time.
:-)
p.a.
You poor saps. It’s Intelligent Falling.
@schrodinger’s cat: It was shy.
Xantar
@Irony Abounds:
There are videos on YouTube which can explain this much better than text, but I’ll give this my best shot.
Pretend for a moment that you live in a two dimensional world. Pretend your world existed on the surface of a big trampoline, and all you can see is only x-axis and y-axis.
Now imagine that somebody places a bowling ball on the trampoline. The trampoline would bend and warp around the bowling ball. From your perspective sitting on the trampoline, you would only see some kind of massive object, but you would also find that there’s something drawing you towards the bowling ball. You wouldn’t be able to see the force that’s moving you because remember, you can only see in two dimensions. But nonetheless, the force drawing you towards the bowling ball is completely real.
Einstein said our universe is like that two-dimensional trampoline. We live in four dimensions (the 3-D world plus time). When we experience gravity, it’s because something with mass is warping the “surface” of the universe around it and causing us to fall towards it. We can’t really see into the fifth dimension (or whatever dimension gravity is in), but it’s still there.
peach flavored shampoo
What’s mind blowing, to me, is that these waves originated 1.6 billion years ago. This black hole merger happened prior to life on earth, I believe. Can anyone explain how they determined the source of these waves?
Face
So I’m not fat, I’m just more adept at bending spacetime, right?
schrodinger's cat
@Face: Or you could be just floofy and big boned like Tunch!
p.a.
@peach flavored shampoo:
~ from Smithsonian
@Face: these are weighty philosophical questions.
Paul in KY
@Face: Also, food is attracted to your gravity well. It’s all physics, Face.
redshirt
So what’s the implication for quantum gravity? As I understand it, Einstein’s theory of gravity did not translate to the the quantum level, and quantum research uses their own theory of gravity.
Given that black holes can be thought of as quantum objects, does this help unify to the two theories of gravity?
p.a.
@Xantar: Flatworlders unite! Rise up and throw off… uh, nevermind.
Gin & Tonic
@peach flavored shampoo: Don Lemon told them.
Ex Libris
@shomi: Really sorry you are forced to breath the same air as us dumbos. Watch out for them there gravity waves – a brain as big as yours must have all kindsa gravity issues.
shomi
@Anoniminous: We have a good handle on Maxwells equations. Turns out electrons are a lot stranger than we first thought though. Maybe that’s what you mean
Gin & Tonic
@shomi:
gvg
Poorly kept secret indeed..my employer the University of Florida already has a detailed puff piece about this and UF scientists contributions towards it, a list of other contributors etc. It is a good piece to show the value of the many US universities. Apparently we built one of the pieces of the detector equipment. Also many other top Universities contributed specialized pieces by agreement starting around 1996 so that also demonstrates the value of a long view. Corporations don’t do this much.
Face
@Paul in KY: Exactly! How am I supposed to eat less when all this food keeps getting warped directly into my pie-hole (and then discarded out the black hole….ha!)?
indianbadger
Here is the cooler titbit. Recently the nerds at CERN found the last bit of particle predicted by the Standard model with the discovery of the Higgs Boson. Not only did they find that little guy, but it was smack dab in the middle of all predicted values for what it’s energy equivalent would be (something like 125 eV or something).
Now we have the last bit of prediction from GR. Even Einstein who predicted them basically said we can never find them. Well, Einstein … it is done.
The thing is that at a fundamental level GR and QM are incompatible. Since we have now two theories that have been fully validated; what next? A search for Gravitons to quantize gravity? I ask as a complete amateur, knowing very very little about these things; but what is the next step in trying to reconcile two incompatible; but obviously true (but incomplete) theories?
dmsilev
@peach flavored shampoo: The mass and distance estimates come from comparing the size and frequencies of the chirp with predictions from GR calculations. The position estimate comes from the time delay between the two detectors; once more similar observatories come online, we’ll be able to do more precise localization of similar events, and hopefully be able to quickly slew optical telescopes to point towards them and catch images of transients.
Marc
The reason why this is so important is that it opens up a completely new window on some of the most dramatic events in the universe. Isolated black holes really are dark, so there is no photon signal when they merge. But they produce enormous amounts of gravitational waves – the event today converted three solar masses into wave energy, which is astonishing. The Sun will covert about one part in 3,000 of its mass into light over its entire life.
Mergers of other compact objects (earth-sized white dwarf and city-sized neutron stars) are thought to be responsible for the origin of many of the elements on the periodic table. And all would be “seen” by gravity wave detectors.
The method itself, by the way, takes advantage of the face that space itself is compressed and stretched as a gravity wave passes by; so the time it takes a laser to travel down a tunnel changes because the tunnel actually gets shorter and longer. You look in two places at once to rule out signals like passing trucks that also shake the ground.
shomi
@Ex Libris: What I can say with that stipid comment is that you are either a child, were dropped on your head at some point, or at the very least almost everyone here is a lot smarter than you.
MattF
@redshirt: Einstein’s gravitational theory is 100% ‘classical’, quantum mechanics is nowhere in evidence– so the LIGO measurements have no significance for quantum gravity. Any gravitational quantum effect would be many, many, many, many orders of magnitude weaker than the present measurement– and won’t be seen any time soon, if ever.
schrodinger's cat
@Marc: Gravitational effects become important for extremely large masses, at the subatomic scale (realm of quantum mechanics) gravity is not a factor at all.
Paul in KY
@Face: I think your only hope is to lose a dimension.
Tom Levenson
Gotta say I’m loving the fact that gravitational waves are somehow grist for trolls. What a strange world we live in.
Ex Libris
@shomi: perhaps it’s all four of those
MattF
@Tom Levenson: It’s a discovery– the energy-momentum tensor must have a ‘troll’ term.
Marc
@schrodinger’s cat: And?
Tom Levenson
@MattF: ;-)
Randy P
Fantastic news. Something I didn’t expect to see in my lifetime, frankly.
redshirt
So we exist within an undulating medium.
I wonder if that fact changes any existing theories.
Randy P
@indianbadger: pedantic correction: that’s 125 GeV as in 125 billion eV. For comparison, your standard proton or neutron is about 1 GeV
Matt McIrvin
@PaulW: I don’t know if it counts as “practical,” but the main application is exactly what they were doing here: using these gravitational waves as a way to observe distant things going on in the universe. They detected two black holes colliding in a distant galaxy over a billion years ago. There’s visible-light astronomy, UV and infrared astronomy, radio and X-ray and gamma-ray and cosmic-ray astronomy… and now there is gravitational-wave astronomy.
Matt McIrvin
@redshirt: No, the theory is 100 years old last fall. The hairy computations to predict the emissions from a black-hole collision were finished just over a decade ago. But nobody knew just how common these black-hole collisions would be.
schrodinger's cat
@Marc: In practical terms it doesn’t matter for the most part that these two theories don’t completely gel.
redshirt
@Matt McIrvin: No, I meant all theories and experiments. If we exist within an undulating medium, perhaps the results of other experiments have been misinterpreted, or models didn’t properly factor this variable.
I just wonder what the ripple effect of this confirmation will be.
schrodinger's cat
@redshirt: You do know that gravitational force is the weakest of all the 4 fundamental forces? Not much of a ripple effect. In practical terms this gives us one more way to explore the cosmos.
Germy
Uh oh
http://www.rawstory.com/2016/02/civil-rights-hero-john-lewis-burns-bernie-in-all-my-years-of-activism-i-never-saw-him-never-met-him/
Randy P
@Tom Levenson: Did you get ever read Usenet? The “Einstein wuz rong!” crowd was fairly significant. And they were MAD about it!
Germy
C.V. Danes
@p.a.: Yeah, but things didn’t really get interesting until the Cambrian Explosion about 550 million years ago :-)
Brachiator
@redshirt:
I don’t know. Sounds kinda shaky.
catclub
Isn’t the tensor notation usually Big G{sub mu nu} not big Effing?
redshirt
@schrodinger’s cat: Sure do! I’m just wondering if this would change other theories. Star formation, supernovas, pulsar rotations, etc….
Tom Levenson
@catclub: Well played.
Matt McIrvin
@redshirt: No, everybody’s had to deal with this for a long time.
The effect on most areas of physics is negligibly small, and where it is significant, everyone already assumed it to begin with, because the theory has been the standard one of space-time for about a century.
And the existence of gravitational waves was actually indirectly observed all the way back in the 1970s, when astronomers discovered a pair of pulsars orbiting each other. These things are fantastically dense, made mostly of neutrons packed like an atomic nucleus. And you can detect the timing of their orbit by observing the Doppler shifts in the pulses.
It turns out that these pulsar pairs gradually lose orbital energy at a rate precisely matching the prediction of what they’d lose to gravitational waves.
This was just the first direct observation. Instead of a pulsar pair, this latest observation was of a black-hole pair, and the gravitational waves they emit when they finally spiral in to a collision are far stronger, which is part of why they could be directly detected.
John Revolta
@schrodinger’s cat: Yeahbut what about the theory that all 4 forces are actually the same force? Does this make that more likely, less likely, as likely?
p.a.
@C.V. Danes: Hallucigenia! :-o
redshirt
@Matt McIrvin: Thanks.
Do gravity waves play any role in new star formation? Or are they too weak to perturb the dust clouds?
Matt McIrvin
@redshirt: I would guess not; they are very, very weak.
schrodinger's cat
@John Revolta: Grand Unified Theory is the holy grail of theoretical physics, and not yet in sight AFAIK.
p.a.
@redshirt: You’re in Maine, correct? If you’re near Ellsworth or Kittery and like Celtic fiddle and World Music, check out Mari Black’s upcoming shows.
? Martin
Next outstanding question – what is the speed of a gravity wave? The general guess is that gravity waves travel at exactly the speed of light. Better question is – why do they both travel at the same speed?
There hasn’t been any real doubt in the physics community that gravity waves existed. The ability to actually measure them is exciting, though. It is indeed a BFD. Effectively, we just invented the telescope. There are some long-term plans to put a gravitational wave telescope in orbit. That should allow them to observe binary stars within our galaxy. Hopefully those plans will get sped up a bit, though they are very ambitious constructions.
redshirt
@p.a.: I am, but no where near those towns. Thanks for the tip though.
redshirt
Do gravity waves interfere with each other?
Randy P
@? Martin: Theoretically gravitational field changes propagate at the speed of light. AFAIK nobody has yet come up with a good experimental test of it.
Edit: I guess I’m out of date.
http://www.universetoday.com/121284/how-fast-is-gravity/
“When they did the calculations, astronomers determined the speed of gravity to be within 1% of the speed of light – that’s close enough.”
Germy
this is a nice article on the subject:
http://www.newyorker.com/tech/elements/gravitational-waves-exist-heres-how-scientists-finally-found-them
redshirt
@Germy: LePage named this black hole “Shifty”.
Anoniminous
Deleted by user
henqiguai
@Face(#47):
Um, I believe the ‘thinking’ is inflow is the black hole, outflow is the, um, white hole.
Ultraviolet Thunder
I call dibs on Gravity Waves for my new band name.
That is all.
redshirt
@Ultraviolet Thunder: That’s a good name. Surf rock with space themes. Get Brian May on line 1!
Ultraviolet Thunder
@redshirt:
Planet Waves was already taken by some old dude from Minnesota.
redshirt
So, someone smarter than I correct me:
I see a chain of phase transitions caused by gravity that shape our universe:
Dust collects in clouds; that dust is perturbed and begins to rotate, eventually reaching such densities that fusion occurs and a star is born; if the star is of a certain size, it will eventually collapse, forming a neutron star as a result; but if that star was even bigger, it’s collapse will create a black hole; black holes can merge with other black holes, creating bigger black holes.
Does that describe the phase transitions of matter?
Germy
Trump meets the Honeymooners
https://www.youtube.com/watch?v=3XriXDtfqCg
Soylent Green
Finally. Incontrovertible proof of Fudd’s First Law of Opposition.
Matt McIrvin
@? Martin:
They do travel at the speed of light, according to the old binary-pulsar results and the numerical calculations here (which are dependent on the speed of gravitational waves).
LIGO had a detector in Washington state and a detector in Louisiana, so by measuring the relative delay, they could directly measure the component of the wave velocity along the line between the two. But I don’t know if they could constrain the direction of travel enough to turn that into a direct measurement of the speed of the waves.
Anyway, as to why, the speed of light (in vacuum) is built into the geometric structure of the universe according to general relativity. It’s nothing specifically to do with electromagnetism; it’s just the speed at which any particle with no rest mass, or any disturbance in a field theory with no mass terms, will travel. And that includes disturbances in the space-time geometry itself.
I don’t know if that’s much of an answer or not.
Ultraviolet Thunder
@redshirt:
You might remember my old band the Moderate Rebels.
Robert Sneddon
@Randy P: RE: The Jiant Branes of Usenet — the name “Brad Guth” percolated into my consciousness a couple of days ago, for no apparent reason. Not quite “Time Cube” levels of derk but up there in the top leagues.
Robert Sneddon
There have been attempts to detect gravitational waves in the past with some claims of success but the noise levels prevented them from being widely accepted.
The supernova SN1987A reportedly produced a signal from at least one gravitational wave detector, a device based on isolated large masses — a supernova collapse involves a lot of mass moving very fast in a short period of time and is thus a good candidate for producing such waves, much smaller than the colliding black holes would produce but SN1987A was a lot closer in time and space to us than the event detected in September last year.
indianbadger
@Randy P:
Thanks. I knew the 125 but not the units. Crazy how you remember some things but not others.
p.a.
@Ultraviolet Thunder: Loved your albums White Lines and Deliberate Speed
redshirt
At this point, where does Einstein rate among the most important thinkers in the history of the world? He’s got to be top three, if not number one. But Newton, Galileo, Plato, Aristotle might contend.
Robert Sneddon
@redshirt: Einstein took the experimental results of others which contradicted the billiard-ball vision of the Newtonian Universe (Michelson-Morley experiment, the ultraviolet catastrophe, the orbit of Mercury and some others) and deduced that matter and energy were equivalent forms of each other, linked by the speed of light, the famous E= Mc^2.
The experimenters went out and started looking and measuring and every time they found that Einstein was right, righter than Newton and Copernicus and Kepler who were only approximately correct. One of the first big proofs was the problem of the orbit of Mercury which didn’t quite match classical mechanics because it is so deep within the Sun’s gravitational well. Relativity explained the anomaly.
I’d put Einstein at the top of the table for that result alone although his Nobel prize was for another non-relativity problem, the “ultraviolet catastrophe” where he posited the wave-particle duality of electromagnetic radiation which eventually led to quantum theory.
It’s likely others would have figured things out given time but he was the first to write it down and make it known.
moderateindy
Meh Physics, what has it ever done for anybody? Just another case of so-called scientists making stuff up so that they can get rich off of them sweet, sweet government research grants
More importantly: did anyone see The Kardashians last night?
…………Idiocracy, it’s closer to an actual documentary than we want to admit
Bill Arnold
@Randy P:
Tx for the correction. There was a “wait, what??” moment before I realized it was a typo but read on.
Bill Arnold
@Robert Sneddon:
Have you seen the Time Cube generator? Time Cube (generator – reload for more)
Also on that site, “Band Names”, “Postmodernism”, “Adolescent Poetry” are good.
moderateindy
Honestly, I don’t find it nearly as cool as the research funded by NASA that there is evidence that the Earth is actually two planets that collided, and fused together.
Bill Arnold
@moderateindy:
Irritating party game, which I’ve mentioned here.
“Name a famous living scientist, not the guy in a wheelchair”
Worse yet is
“Name a famous living engineer”
redshirt
@Bill Arnold: Does Elon Musk count for both?
Bill Arnold
@redshirt:
Probably he counts for both. Did he ever publish in physics?
I’m 0 for about 20 on the “famous living engineer” question, face to face at parties, BTW.
Matt McIrvin
@Robert Sneddon: Planck really was the one who tackled the ultraviolet catastrophe by proposing that radiation was quantized. Einstein took the same idea and used it to explain the photoelectric effect, which I think was what he officially got the Nobel for.
The Fat Kate Middleton
Finally managed to get away to read the various articles on this … I still have goosebumps. This is one of those developments that make me feel glad – for the first time in years – to be living in this time.
Steeplejack
@Germy:
Hah! I was going to post that earlier today, but I could find it only as part of a much longer YouTube clip. Here it is in context.
Bill Arnold
Just wanted to say that this is one of those times that I feel extremely proud (tearing proud) to be a human being.
3 solar masses converted into a short chirp.
(Parent article is good, if it hasn’t been linked here yet.)
Robert Parson
@Matt McIrvin: No, Planck did not propose that radiation was quantized, nor he was not trying to resolve the “Ultraviolet Catastrophe”. This is a myth created by early popular histories of quantum theory (e.g. d’Abro and Gamow) and propagated through about three generations of physics (and chemistry) textbooks. To see how wrong it is, just note that the Rayleigh-Jeans paper, which is where the idea of an “ultraviolet catastrophe” originated, was published five years afterPlanck’s 1900 paper, in which he derived his famous law. See Helge Cragh’s article in Physics World, http://physicsworld.com/cws/article/print/2000/dec/01/max-planck-the-reluctant-revolutionary.
This isn’t a recent discovery – historians of physics have been arguing this point since about 1950 – but textbooks are slow to keep up. It’s not at all clear just what Planck was thinking about in his 1900 paper, but he seems to have regarded dividing up energy transfers into increments as a computational device, not as something fundamental. Einstein was the first physicist to take these increments – “quanta”, “photons” – seriously.
Irony Abounds
@Xantar: I appreciate the explanation, thank you. Still kind of baffled by the “spacetime” reference. I have trouble getting past bedtime, lunch time and dinner time.