Einstein’s theories gave scientists good reasons for thinking gravitational waves exist. A century later, instruments detected the elusive radiation.
Three American scientists won this year’s Nobel Prize in Physics for work that led to the discovery.
Observatories in America and Italy have detected three more gravitational wave signals. What they learned wasn’t quite what they expected.
- Dealing with reality
- In the news
- Looking over the horizon
Patriotism, Within Reason
I would have read about this year’s Nobel Prize in Physics, no matter who they picked.
But seeing American scientists given the award lets me enjoy patriotic feelings. Within reason.
I like being an American, for the most part. It gives me a particular focus, and helps me see the world through my culture’s filter. That makes understanding what folks around me say and do a bit easier.
I also like being a Catholic.
That lets me enjoy being an American and remember that we live in a big world: without unreasoning fear or arrogance. (Catechism of the Catholic Church, 1934–1942, 2238–2243)
“…Citizens must cultivate a generous and loyal spirit of patriotism, but without being narrow-minded. This means that they will always direct their attention to the good of the whole human family, united by the different ties which bind together races, people and nations….”
(“Gaudium et spes,” Blessed Pope Paul VI (December 7, 1965))
It’s been about two dozen centuries since Empedocles thought Aphrodite made human eyes from the four elements: earth, air, fire, and water. Giving Aphrodite credit for our eyes made sense, given his culture’s assumptions.
We’ve learned a bit since then.
Most of us, anyway. Some folks seem dedicated to the belief that God gets offended when we study God’s creation. Particularly if we learn something that doesn’t fit their assumptions. I figure God gave us brains, and I’ll get back to that.
Maybe they haven’t quite shaken off the idea that intruding on nature offends ‘the spirits.’ I can’t know what happens in another person’s mind, so that’s speculation. Fallout from 19th century English politics doesn’t, I think, help. (October 28, 2016; July 15, 2016)
Empedocles said we can see because fire shone from our eyes. Humans don’t have particularly good night vision, so that couldn’t be the whole answer.
He figured vision depended on interaction between fire from our eyes and fire from other sources, like the sun. That made sense, given what folks knew in his day. Plato’s view of vision was on pretty much the same page.
Euclid saw problems with the ‘fire’ model, but wasn’t nearly as influential.
The paper trail for Euclid’s personal life starts more than eight centuries after his death. We don’t even know when or where he was born. We probably wouldn’t know anything about him, if folks hadn’t made a point of keeping records of his work.
Euclid thought about light and vision, applying math to the ideas. His “Ὀπτικά,” “Optics,” deals mostly with geometric aspects of light. He realized that sight had physical and psychological aspects, but that wasn’t his focus.
Euclid did, however, think that beams from our eyes probably weren’t how vision works. We see stars right away when we open our eyes at night. He figured that wasn’t consistent with the ‘fire’ model. He was right about that.
Ptolemy and Galen thought Empedocles and Plato were right about sight. It wasn’t until about a thousand years back that European scholars started wondering if maybe there’s another explanation.1
A Latin translation of Ibn al-Haytham’s “Kitab al-Manazir,” “Book of Optics,” helped.
So, I think, did work by folks like Saints Albertus Magnus and Hildegard of Bingen. They weren’t, strictly speaking, scientists. But they helped get today’s science started.
Albertus Magnus helped make Aristotle’s ideas available to European scholars. I see no problem with that.
Aristotle is a pretty good role model for folks who see thinking as a good idea.2
Some European scholars got overly-enthusiastic over their favorite philosopher.
Thinking someone is top in their field is okay. Within reason. Forgetting who’s in charge isn’t.
One of the topics being discussed was whether we were on the only world.
It was a reasonable question at the time. The telescope was still a few centuries in their future.
Aristotle’s fans said that other worlds couldn’t exist: because Aristotle said so.
I’ve mentioned Proposition 27/219 of 1277 before. It’s no longer in effect, but the principle still holds.
God decides how reality works. We don’t. (Psalms 115:3; Catechism, 268)
The ‘God or Aristotle’ question came up again, a few centuries later. Folks like Copernicus and Galileo were taking a fresh look at astronomical assumptions. European politics of the day were more volatile than usual.
I figure any new ideas would have given some folks fits. (April 28, 2017; March 24, 2017)
Tensions between northern and southern European powers gave us the Reformation, Thirty Years’ War, and Enlightenment.
I think we’ll be cleaning up the mess for centuries. The good news is that we’ve made significant progress, and that’s another topic. (August 20, 2017; November 6, 2016; October 30, 2016)
Where was I? Physics, Aphrodite, assumptions. Right.
Waves? Particles? Both?
Folks were rethinking Aristotelian physics in the early 1600s.
One of the questions was how light works. Some said waves were a good model. Others said light acts like particles.
Huygens, Boyle, and others said ‘waves.’
Others, including Gassendi and Newton, said ‘particles.’
I appreciate Gassendi’s efforts to steer between skepticism and knee-jerk dedication to dogma. His efforts to merge Epicurean atomism with his views of Christianity probably made more sense at the time.3
About the ‘waves or particle’ question, we’re pretty sure the ‘wave’ and ‘particle’ folks were both right. Sort of.
Quantum mechanics makes sense, so far. Light acts like particles and waves. Subatomic particles act like waves and particles.
I’m quite sure we haven’t found a complete explanation for how reality works. But we’ve found a few more pieces of the puzzle.
Isaac Newton published “Opticks” in 1704. His argument for a corpuscular theory of light was a good-enough match with observations.
But it didn’t account for diffraction. Newton suggested that an aethereal medium caused that effect. Newton had earned a considerable reputation and his optical theories were reasonable. The scientific consensus was that Newton’s corpuscular theory was right.
Scientists kept studying light. That’s how science works. Accepting a theory means testing it: not tabling the question. It’s how we keep learning more about this universe.
If the corpuscular theory and luminiferous aether models described how light works, better tech and more precise data would match them, or at least come close.
That wasn’t happening. Scientists were increasingly convinced that they needed a model other than Newton’s aether.
Michelson Interferometers, 1887-2017
Albert A. Michelson started improving interferometer tech in the 1880s.
Research sparked by the 1887 Michelson-Morley experiment eventually showed that luminiferous aether isn’t there.4
We’ve used the same tech quite a bit since then. Scientists and technicians have been using Michelson interferometers for spectroscopy, testing optical equipment, and measuring stars.
But the Michelson-Morley experiment was probably that interferometer design’s most famous use.
The LIGO and VIRGO detectors are Michelson interferometers. They measure gravity waves instead of light.
Newton’s law of universal gravitation is still “true” in the sense that it is a very good approximation for large masses and low velocities. We still use Newtonian physics when dealing with planetary orbits and navigation the Solar System.
Newton offered some tentative ideas about why gravity works the way it does. He thought we didn’t know enough at the time to be sure.
Oliver Heaviside said maybe gravity acts like waves. That was 1893.
Henri Poincaré and Albert Einstein both added math to discussions of gravitational waves in the early 1900s.5 I’ll let historians who haven’t been born yet sort out how much each of them helped solve that particular puzzle.
Gravitational waves kept making sense as scientists analyzed more data. We’re pretty sure they’re a good way to describe the phenomenon. I’d be astounded and a bit disappointed if they’re the full answer, though.
Gravitational waves are analogous to the electromagnetic waves we call “light.”
That started me thinking about where ‘gravity astronomy’ may be going.
We could probably make ‘gravity telescopes,’ giving us images formed by gravity waves. Eventually. Maybe.
Saying that we’re not close to building something like that is a massive understatement. Just detecting them is impressive today. So is telling where their source is.
Getting a general bearing on incoming gravitational waves is possible because they travel at speed of light. We’re pretty sure about that. That seems to be as fast as anything can go through spacetime.
With at least one, probably two, exceptions.
The last I heard, quantum entanglement is either instantaneous or significantly faster than light. Physicists don’t know why. Not yet.
My guess is that the phenomenon, however it works, doesn’t show that Einstein’s theories aren’t true. Just that the universe has a new set of puzzles for us to solve.6
1. Nobel Prize in Physics, 2017: LIGO Scientists
(From AFP/CALTECH/EPA, via BBC News, used w/o permission.)
(“Weiss (L) takes half the prize; Barish (C) and Thorne (R) share the other half”
“Einstein’s waves win Nobel Prize in physics”
Paul Rincon, Jonathan Amos, BBC News (October 3, 2017)
“The 2017 Nobel prize in physics has been awarded to three US scientists for the detection of gravitational waves.
“Rainer Weiss, Kip Thorne and Barry Barish will share the nine million kronor (£831,000) prize.
The ripples were predicted by Albert Einstein and are a fundamental consequence of his General Theory of Relativity.
The winners are members of the Ligo-Virgo observatories, which were responsible for the breakthrough….”
I’m a little surprised about this Nobel Prize. It’s good news, of course, for the three scientists and their outfits: Massachusetts Institute of Technology and California Institute of Technology. It’s nice to see Americans get recognized, too.
What’s surprising is that it’s awarded so soon after the first detection. Nobel Prize in Physics rules say that achievements must be “tested by time.”
Early 2016 to 2017’s autumn isn’t much time. The Nobel Prize press release explains that the award recognizes personal work going back several decades.7
I talked about gravitational waves a few months back. (March 24, 2017)
They’re wrinkles in spacetime. Scientists figured they might exist, starting in the late 1800s.
Technology developed during the 20th century let scientists start designing instruments that could detect gravitational waves. That started about a half-century back. By the 1980s we had prototypes.
(From Umptanum, via Wikimedia Commons, used w/o permission.)
(The LIGO Washington State detector’s north arm.)
The first LIGO observatory operated from 2002 to 2010. It detected no gravitational waves.
No detection might mean that gravitational waves didn’t exist. Or maybe they existed but didn’t act as scientists thought they would.
Scientists figured no detection probably meant that their first-generation technology wasn’t sensitive enough.
That, I think, isn’t refusing to believe evidence.
Scientists have been unreasonably stubborn, Priestley apparently ignored his era’s chemical science. It didn’t prove his phlogiston theory.8
Assuming that their first efforts detected no gravity waves was acknowledging that LIGO technology can be improved. That’s how I see it.
As it turns out, they were right. Gravitational waves are there.
Gravitational waves from merging black holes passed by Earth on September 14, 2015.
The LIGO detectors in Washington State and Louisiana, operating in engineering mode, detected them. Scientists with LIGO and Virgo analyzed the 0.2-second ‘chirp,’ publishing their results February 11, 2016.
This may not be the single most important experimental confirmation in the last half-century. CERN scientists observed W and Z bosons in 1973, for example.
It’s important, too. Ranking experimental results for different phenomena can be more than a bit subjective.9
But detecting gravitational waves is very important for physicists and astronomers.
They’ll let us ‘look’ at this universe when it was very young. It was opaque for about the first 380,000 years.
That’s when it cooled enough for photons to travel any significant distance.
The cosmic microwave background is the the oldest electromagnetic radiation we’ve observed: or can observe.
Gravitational waves don’t interact with matter the same way as electromagnetic waves. The early universe should have been transparent to gravitational waves in those very early years.
We’re hoping to learn a great deal about that era by observing gravitational waves.
2. EGO: Fourth Gravity Wave Detection
(From Virgo Collaboration, via BBC News, used w/o permission.)
(“The VIRGO detector in Italy has helped narrow the search on the sky”
“Gravitational wave hunters bag fourth black-hole detection”
Pallab Ghosh, BBC News (September 27, 2017)
“Scientists have detected another burst of gravitational waves coming from the merger of two black holes.
“The collision occurred nearly 2 billion years ago, but it was so far away that its shockwave has only just reached us.
“This is the fourth confirmed detection made by an international team investigating Einstein’s Theory of General Relativity.
“Sheila Rowan of Glasgow University, UK, said the team was now on the threshold of a new understanding of black holes….”
I don’t know who got the Virgo Collaboration started, or why they picked that name. They use VIRGO as an acronym sometimes. I haven’t learned what it stands for.
In my language, it could mean Very Intelligent Researchers’ Gravity Observatory. But I think that’s unlikely. Very unlikely.
Whoever got the ball rolling, the project officially started when French and Italian researchers at CERN and INFN gave it their approval in the 1990s.
Folks started building EGO, the European Gravitational Observatory, in 1996. It’s near Pisa. Construction was finished in 2003.
Scientists and technicians had the first VIRGO detector ready in 2000. They stopped using it in 2011. They’d detected no gravitational waves.
That’s pretty much what they expected. Their first-generation detector wasn’t particularly sensitive. I gather that it was mainly a proof of concept device, with detection as a possible but unlikely bonus.
Their tech behaved the way they hoped, so the European scientists got to work on more sensitive detectors.10
Folks with LIGO and Virgo kept working on their own projects, and cooperating. This wasn’t a replay of the infamous bone wars. (May 5, 2017)
Finding Nothing Means Something
(From LIGO Scientific Collaboration and Virgo Collaboration, via Wikimedia Commons, used w/o permission.)
(Where astronomers looked for gravitational wave event GW170814.)
LIGO observatories in Washington State and Louisiana are about 3,002 kilometers apart. That’s 1,865 miles. At speed of light, a gravity wave would take up to ten milliseconds to travel between them. It’s not a long time, but long enough to detect.
Add the Virgo observatory in Italy, and we’ve got three observation points for GW170814. That’s enough to get a bearing on where waves come from.
Not a particularly precise bearing, though. Scientists narrowed down GW170814’s location to somewhere in a region of Earth’s sky the size of 300 full moons.
The recent gravitational wave detection is Virgo’s first. That’s a big deal for the Virgo Collaboration.
It’s also important because astronomers got a bearing on the wave’s source fast enough to follow up with optical telescopes.
It’s a big search area. But several observatories were on the job, and we’re getting better at catching transient phenomena.11
Astronomers figured they might spot something. They didn’t.
Again, not observing something doesn’t mean that something isn’t there.
In this case, not spotting electromagnetic radiation from a gravitational wave source may mean that the merger of two black holes pulled in everything near them.
Many theoretical models for how black holes merge say that’s what happens.
Having the Virgo observatory’s observations and LIGO’s made measuring polarization of GW170814’s gravitational waves possible. That’s another “first.”
It’s a Start
We now have four more observations of gravitational waves than we did in early 2015. It’s a good start, but just a start.
Detecting gravitational waves confirms that they exist, and that at least part of the math describing them reflects reality.
Gathering data, testing predictions, is an important part of the scientific method.
When some of the data isn’t quite what we expected, part of a scientist’s job is figuring out why it doesn’t match.
Gravitational waves observed so far are a pretty good match to what scientists expected from black hole mergers. There’s an odd pattern emerging, though.
All four collisions apparently involved black hole pairs where both were about the same mass. Getting pretty close matches four times in a row is odd. The pairs are a bit more massive than expected, too.
Four is a small sample. More observations will almost certainly answer some questions: and, I think, raise many more.
So will data from gravitational wave observatories in Japan and India.12
God Gave Us Brains
I really do not believe that God gets offended when we use our brains.
I think God sustains this universe. I also think that humans are rational creatures. We don’t consistently use our brains. That’s because we have free will. (Catechism, 300–311, 1704, 1730–1731)
Sometimes we make really bad decisions.
I suspect part of the problem is that using emotions as a guide, following whatever impulse bobs up from our brain’s background processes, is easier than thinking.
We’re basically good, but got off to a really bad start.
And that’s yet another topic. (March 5, 2017)
Euclid, Alcubierre, and Beyond
Many scientists say Miguel Alcubierre’s math makes sense.
The Alcubierre metric is a Lorentzian manifold — a way of describing space mathematically.
It’s the sort of thing Euclid did: plus what some of my civilization’s best minds have been adding to the mix since then.
Discussions have shifted from whether the Alcubierre equations make sense, to how they relate to the rest of observed reality. Also how we can use them.
Data from the White-Juday warp-field interferometer tests may be inconclusive. I think that’s partly because we’re in a very new field.13
My guess is that we’re centuries from flight testing a warp drive. It’s not the science so much as the engineering. And that’s yet again another topic.
Euclid, Newton, Einstein, and still learning:
- “New Worlds: The Search Continues”
(June 2, 2017)
- “Repeatable Results That Aren’t”
(April 28, 2017)
- “Knowledge: Opening the Gift”
(March 26, 2017 )
- “Baryons, Gravity Waves”
(March 24, 2017)
- “Making a Universe: Why Bother?”
(January 29, 2017)
1 Studying this universe, the early years:
3 Waves, particles; and gravity:
6 A few questions answered, and lots more questions:
- “Physics, an Overview” (page 69)
- “Press Release: The Nobel Prize in Physics 2017”
NobelPrize.org (October 3, 2017)
- Nobel Prize in Physics
- Rainer Weiss
Massachusetts Institute of Technology
- Barry Barish
California Institute of Technology
California Institute of Technology
- “Physics, an Overview” (page 69)
- “LIGO’s Interferometer”
LIGO (Laser Interferometer Gravitational-Wave Observatory), Caltech
10 European cooperation in science:
- European Gravitational Observatory (EGO)
11 Observing ‘blink and you’ll miss it’ events:
12 Gravitational wave observatories in India and Japan:
Fascinating post as usual Brian. I have a theory on this statement you made: “What’s surprising is that it’s awarded so soon after the first detection. Nobel Prize in Physics rules say that achievements must be “tested by time.”
Given that they award a prize annually, I think they’re just running out of time tested achievements. Anyway, I posted on the Nobel Prize in Literature, so we’re on similar wavelengths – no pun intended. 😉
Your Nobel Prize in Literature post – http://ashesfromburntroses.blogspot.com/2017/10/literature-in-news-nobel-prize-in.html – is something I’ll most likely read tomorrow. About what I saw: agreed. That press announcement looks odd. Maybe it’s a translation hiccup. Or something entirely different.
The “tested by time” thing – That seems reasonable. If nothing else, research seems to move much faster these days. Partly, I think because we’ve been upgrading communications tech. Thanks for taking time to read and respond, and your good words.
Extra word: “down to GW170814’s location to somewhere in a region”
Another extra word: “to how about they relate to the rest of observed reality.”
The Friendly Neighborhood Proofreader
Whoops. Fixed, and thanks!