From the AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
Science has chosen as its 2017 Breakthrough of the Year the first observations of a neutron-star merger, a violent celestial event that transfixed physicists and astronomers. As the two neutron stars spiraled together 130 million light years away, they generated tiny ripples in the fabric of spacetime called gravitational waves, sensed by enormous gravitational wave detectors on Earth. This merger also triggered an explosion studied by hundreds of astronomers around the world. Researchers first picked up on gravitational waves over two years ago, when two massive black holes crashed into each other.
This space tremor was detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO), a discovery that landed Science‘s Breakthrough of the Year for 2016 and won the 2017 Nobel Prize in Physics. The discovery showed that gravitational waves offer a new way of observing the universe and a major tool for astronomers. “Gravitational waves are the gift that keeps on giving,” explains News Editor Tim Appenzeller.
“Observers not only detected gravitational waves from a collision of two neutron stars; they also saw the event at all wavelengths of light, from gamma rays all the way to radio. Being able to get the full picture of violent events like this promises to transform astrophysics, and that made this year’s observation the clear Breakthrough for 2017.”
On 17 August, gamma-ray detectors and radio telescopes sensed the merging of neutron stars. Because the ripples were spotted by three widely spaced detectors, scientists acted quickly and triangulated on the pair’s location in the sky.
“Within just 11 hours, several teams had pinpointed a new source on the edge of the galaxy NGC4993. The explosion was easily the most-studied event in the history of astronomy: Some 4,156 researchers from 953 institutions collaborated on a single paper summarizing the merger and its aftermath,” says Science staff writer Adrian Cho. He further notes, “Astrophysicists say the neutron-star merger only whets their appetite for more data.”
Plans are already underway to improve LIGO’s sensitivity at higher frequencies. Scientists will begin such efforts by manipulating the laser light circulating in the detectors, though such an endeavor might take a few years.
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Fascinating. It will be nteresting to see more of the corroborating data.
Depending on ones understanding of science and scientific proof, a model that predicts data with many sigmas’s of precision is perfect statistical proof. The conspiracy of ignorance masquerades as common sense.
Sadly, LIGO’s inconsistencies make it more of a fake news, and a money burning scheme. There is a discussion going on about it on RG, and it is not going well for the LIGO.
What is “RG”?
I’m still sceptical about LIGO. When I first read that they’re “measuring” an expansion/contraction that is a fraction of the width of a proton, I thought there is NO possible way that they could measure a distance that small – using 4km long lasers. Natural background noise would overwhelm the data by many orders of magnitude. And as it turns out – they don’t measure it. What they do is use COMPUTER MODELS to filter out the noise and presto, the data they want appears.
Maybe they really have achieved it, but when ever I read that people are using computer models to give the data they are looking for, I become sceptical.
Gimme a break. This is not a Parmesan.
So can you make an actual argument based on knowledge of the issue ? Or do you just rely on ad-hominem abuse ?
I was skeptical also but, as the mentioned, “they also saw the event at all wavelengths of light, from gamma rays all the way to radio”. In other words, there was independent verification of the event based on the detection by LIGO. Oh, and not one but two interferometers detected the event and they were able to give a general direction based on that. Two having a false signal at the same time coupled with the ability to independently detect the event by other means certainly gives a lot of credence to them working.
It was seen by 3 detectors VIRGO in Italy was online. The optical and radio telescopes would also never have seen the event without LIGO first triangulating it and the refinement of the direction was only because they had 3 detectors. The event only lasted days and you had to be looking at that area of sky a needle in a haystack thing without the GW detectors. All 3 are back in operation from Nov 30 and so early in new year there will be new detections because they are fairly common.
Yeah, having the event visible on whatever frequencies that could be detected is quite strong affirmation that something was happening. If it was an artifact of one instrument, then the other unrelated instruments would not be detecting anything.
Bear, I have been taught that gravity is an instantaneous thing, if they detected something at the same time as all the light frequencies something is amiss. Either their theories on gravity are wrong or they detected something else?
GR has always predicted that gravity propagates at c, while Newtonian mechanics typically treat it as instantaneous. Since Newtonian math is usually good enough for satellites in Earth orbit or space craft in our solar system, we usually go w/those in day to day applications. For one thing, the math is WAY easier, for another the precision gained is usually — but not always! — swamped by perturbations from other objects/phenomena.
That said, many experiments have been done which seem to show that gravity/gravitational waves do propagate at a finite speed, c. Among these are the difference in position of oceanic tides on Earth vs the position of the Sun (solar perspective vs geocentric) & the bending of light from distant stars past Jupiter (when we see it vs when we expect to see it). The most famous example, perhaps, is that of the precession of Mercury’s orbit: predictions done using Newtonian mechanics eventually diverge from observation by a significant amount… so much so that it was noted back in the mid-1800s; GR, using a light-speed propagation of space-time deformation to explain gravitational effects, is accurate to within the margin of error for observation even using today’s instruments.
My knowledge of physics is not very good, but I think you are going by Newton, not Einstein.
ggm, I understand your skepticism about computer models. But they are only a tool. If someone tries to use a hammer to saw wood you can say that they used the tool badly. Not that it is a bad tool.
Factually we use models all the time, and you couldn’t get very far in life without them. When you are driving, don’t you look at the gas gauge? Failing to look at the gas gauge ends badly. But you are using a simple model every time you do it – a 16 gallon tank, gauge shows 1/4 full so I have 4 gallons left, at roughly 20 miles per gallon I can only drive 80 more miles. Better not get on that freeway that has the sign “NO GAS FOR NEXT 100 MILES”.
Of course this simple model has all kinds of flaws. Gas gauges are notoriously inaccurate. Mine shows “empty” when there are still about 5 gallons in the tank. You don’t really know if you get 20 miles per gallon on the gas that is in your tank. If it is contaminated with ethanol you will get less, if you drive fast or hit tons of stop lights you will get less. If you are wise you won’t trust it much beyond the simple observation that it is getting low and you’d better get gas soon.
But it is still a model and it still uses computation (even if you are using a gray matter computer). It still follows the basic laws. You have a physical “law” which is more or less established (gallons of gas times MPG equals miles travelled). You also have tons of parametrizations. These are what we used to call “simplifying assumptions”. You assume a fixed number for MPG when it is really changing every time you change how you drive, the temperature, the type of gas, altitude and so on. You assume the gas gauge is accurate or you may know corrections that make it more accurate (EMPTY means 5 gallons left). Despite all these sloppy inaccurate features you can use it to make valid decisions. You just have to factor in a large error band and err on the safe side.
I use models all the time at work, doing design engineering of electronic equipment. You use models all the time. If a model is being used, it is vital to know how much of the model is parametrized and how much is truly based on basic physical principles. You have to know the error bands on the data that is going into the model and the error bands of error sources in the model.
This is where the IPCC CMIP5 models break down. So many of the important details are buried in proprietary code or hidden by the complexity of the model. And so many parametrizing assumptions are made. There are examples of circular reasoning. They have to average model runs with slightly altered assumptions and use many models, a strong indicator of a weak tool. They are poor at hind-casting and their forecasting tends to blow up into catastrophic warming no matter where they start or what assumptions they use.
It is just as bad as using a screwdriver to open a tin can. But that doesn’t mean screwdrivers are bad.
Screwdriver to open a tin can. Great analogy!
Not to be facetious because I accept your point generally, but maybe your car stops with 5 gallons of fuel remaining. If the pick up tube is bent upward?
The problem with models is when they stop being tools and become solutions. And what sort of tools are they, anyway? They should be used to guide investigation, not to provide answers. Their use in climatology has been as a substitute for science. If astrophysics operated like climate science they wouldn’t have looked for the object with optical telescopes for fear of proving themselves wrong.
By the way, I once owned a Dodge Shadow that seemed to run out of gas at an 1/8 of a tank. But then it started up again an hour later. Long story short I eventually figured out that the fuel got too hot from recirculating through the fuel pump in hot weather with the tank level low and caused it to vaporize or cavitate (can’t say which, the science isn’t “settled”) .
My model was correct, my assumptions about what other factors might mimic the observations coloured my interpretation of the model result. Thank goodness climate is much simpler than a car engine./sarc. Also , my career wasn’t on the line if I dealt with the problem truthfully.
Excellent analogy. I have a Ford Windstar that was top of the line – 15 years ago. One of its features is a digital readout that says how many miles until empty.
Last week, it was disconnected from the battery for a few days while I tracked down the right replacement relay for it. When I got it back up, it was using the “factory new” figure for MPG – about 21 miles per gallon. Regathering its experience in our actual driving (mostly city), it went back down to the 17 MPG that is normal for it. (The engineers obviously knew what they were doing, too – get below 50 miles left and it starts dinging you about low fuel – they realized it was not going to be accurate right down to even 10 miles left.)
LIGO does much the same thing – they constantly monitor the noise in the system, and use that data to model what it probably is at any one specific time, when they do have a real signal. A good music system does exactly the same thing with a FFT (Fast Fourier Transform).
GGM, the small spacetime distortion is observable because LIGO works by interferometry over a very long distance. The coherent spit laser light has several kilometers of spacetime out and back over which to become slightly out of phase. The slight incoherence in the recombined 1064 nm laser beam IS the gravity wave signal.
The computer processing filters out things like mirror mechanical vibration that could also cause incoherence by varying path lengths along the two perpendicular arms.
There are very interesting papers about the long history of LIGO and how it has become adequately sensitive.
coherent spit… LOL . Some typos are funny.
Never saw it. But it is sort of funny.
When the causality arrow of detection runs in the direction of new detection system => old detection system, you have achieved something useful and real, despite misgivings about models.
BTW, as I’m fond of talking about your stereo system – it’s based on models. All engineering is models, all the way down. They happen to be models that work very consistently.
I can’t remember who came up with this but it’s a good quip – it’s not confirmed science until someone engineers a useful product with it.
In this case, the LIGO folks have engineered a method of finding neutron star collisions that allows the old fashioned telescopes to find the needle in a haystack and observe the same occurrence that they normally would never see. That’s about as confirmed as it gets.
I now believe LIGO is real and effective. I used to be skeptical.
Peter
The models only help tune the filters, they don’t produce the signal. If the models are wrong, the detector either produces lots of false positives – in which case the odds of three agreeing simultaneously is nearly nil, or they don’t produce anything at all.
The data track shows a signal is barely above noise. I am skeptical but open to better data.
You guys are up early this festive weekend.
Thanks for all your hard work.
Merry Christmas to all.
Merry Christmas to you also. If to all WUWT folk.
Up this early all the time.
I’m up most lunchtimes, here in SW France I think it is normal 🙂
SteveT
Not what I heard. And I heard it on the internet.
If the explosion was caused by two black holes (black because no light can leave) how did all that light from the explosion get here?
There was some stuff outside the holes.
Actually, the news is about neutron stars, not black holes. But active black holes do throw hot stuff and radiation around, if you manage to look at the direction at the right time.
Only stuff outside the event horizon. But this was a colision of two neutron stars, so there was no event horizon until the resulting ‘small’ black hole formed, if one did (depends on how much mass was ejected). Hence the multiple observations across the electromagnetic light spectrum.
The article called the event neutron stars colliding twice and black holes colliding one – it was caught in the confusion as well. I am pretty sure it is neutron stars.
The black holes were an early event. This time with the neutron stars they were able to get independent visual confirmation.
What I find interesting about that is the light from this merger that happened in a whole other galaxy reached us at the same time as the gravity waves. This effectively confirms that gravity waves propagate at light speed. That invalidates quite a few theories.
Honor Harrington is going to need something else for FTL communication.
^¿^
No confusion. There have been 4 black hole and one neutron detection. Black hole chirps last a couple of seconds. The neutron chirp lasted about 100 seconds. That plus the EM frequency observations both prove it was a binary neutron star collision.
@schitzree – Preempting David here (assuming he even lurks on WUWT), what Honor uses is the propagation of gravity waves through hyperspace, where “c” has a much higher value.
Handwavium is a fine art. One where few SF authors even manage the skill exhibited by quantum physicists. (See the Wheeler hypothesis that our observation of events now propagated back in time to create the Big Bang…)
schitzree
December 23, 2017 at 6:48 am
– ” What I find interesting about that is the light from this merger that happened in a whole other galaxy reached us at the same time as the gravity waves.”
No, actually the gravitational waves did propagae at the speed of light and they actually arrived well before the electromagnetic radiation…gamma rays 1.7 seconds later (after travelling 130million light years), visible light 8-9 hours later (thus allowing time for optical telescopes to watch it happening), UV, X-rays, radio, etc. also later. To me that’s the interesting bit…only the gravitaional waves travelled exactly at the speed of light…nothing to interfere with them as they are only distorting spacetime. The EM waves interact (albeit only slightly) with other stuff on the way or at the merger site. At least that’s my understanding as an astronomy amateur.
Everyone knows that tachyons travel FTL. Models tell us so. Coincidentally, I am reading all about them right now in Benford’s Timescape.
So the breakthrough of the year wasn’t proving a link between CO&#;8322 and cagw. Michael Mann will be gutted.
Darn being lazy with my CO₂
Maybe I’m a bit ignorant here, but I’m confused. The title mentions the merger of two neutron stars, but the first paragraph talks about the merger of two black holes. So which is it? I was under the impression that neutron stars are not the same as black holes.
Never mind. I read the paragraph again for the third time, and I had misinterpreted the last statement. Apologies for my ignorance. 🙂
I’m sure it’s an interesting set of observations for the physicists involved, but I don’t see why it is described as the “breakthrough” of the year. The instruments were already up and running, and the article describes the use of gravitational waves over two years ago when the black holes were observed to collide.
The collision of the 2 black holes proved that LIGO was working and that they could detect gravity waves. Two years later (recently) they were able to observe a different collision – this time of 2 neutron stars. And this time they were able to observe the collision by > 4,000 scientists at 953 institutes from all over the world AND observe it at every single wavelength and type of detector we have developed over the last decades! They can plug this observational data back into their mathematical models to improve the models and perhaps will see new and unexpected things once the data is fully analyzed. This data may also shed light on long-standing debates within physics and astronomy about the gravitational constant and dark matter/energy – who knows – that is the purpose of collecting new data. No, I am not a physicist or astronomer (actually a biophysical chemist) but I did sleep at a Holiday Inn Express last night. 🙂
One of the results is to identify that neutron star collisions produce heaver elements.
https://www.sciencefriday.com/segments/a-stellar-collision-ripples-in-space-time-and-the-origins-of-gold/
There was negligibly small chance you would have seen the event without LIGO you would have had to have a telescope targetted at that section of space for what was a couple days in the billion years of history of that section of space. The fact you could get such a specific warning of a unique event and target 70 other telescopes at the event made it the obvious choice of breakthrough of the year. Scientists now have data they would never have had without the GW detectors.
the gamma ray burst was independently detected and optical telescopes would have still studied it and recorded the light decay curves.
The ability to detect gravitational waves represents a new and powerful tool for astronomy generally.
Some details here https://www.scientificamerican.com/article/the-future-of-gravitational-wave-astronomy/
LO<Lcomments. But what do you expect from a bunch of skeptics!
LOL, comments. But what do you expect from a bunch of skeptics!
Granit……..you prefer humans that always accept that which is offered; your journey following the Pied Piper needs a Red Pill.
Go back and re-read the newer comments. Self-correcting to a degree – like science.
This thread is exactly what I expect from a bunch of skeptics. It’s a beautiful thing, and I’m probably not the only one learning from it.
Agreed. We all learn, and sometimes we can contribute snippets from our own specialised areas. Except ristvan, of course, he has no specialised area because he knows everything (well, nearly everything). No offence intended; polymaths are valuable assets and we’re lucky to have one of our own.
electrician exactly! geologist/mining engineer here, happy to be learning this beautiful stuff from the world’s smartest and most generous people. I believe that here at Wuwt university my knowledge of climate now surpasses that of most mainstream climate scientists, and I never got started until i was in my 70s.
It’s a breakthrough because their new ability to detect and measure gravitational waves is allowing them to find and pinpoint and study some rare events in the universe that we can learn from. In this case the collision was studied “as it happened” rather than after-the-fact and lots of useful data was gathered. But in the future who knows what it will lead to?
“As it happened”. It may be just me, but I have a hard time wrapping my head around that. So I guess gravitational waves travel at the speed of light?
That is the theory. General Relativity predicts it should travel at light speed.
In Astronomy, “As it happened” means millions of years after it happened but when the perceivable effects reach the Earth. You just have to know the lingo…
Not just theory measured by between the 3 detectors for the detections current measurement at 299,792,458 metres per second
Given that the LIGOs have only been operational for a few years, its is more likely they are not so rare. There’s enough galaxies within 100Mparsec to push a 1E-07 events/galaxy/year probability to see one every few years.
Try every 2-3months and they have increased the sensitivity and the detectors have been running again since 30 November so expect new detections in new year.
Telecomms merge. Stars collide.
Once in a while a vehicle fails to merge correctly on the freeway and a collision ensues. Merge is kind of a poor term for a violent celestial concurrence, unless speaking of merging galaxies, which will also cause collisions in the process.
Actually, I heard somewhere – Carl Sagan? – that merging galaxies produce no collisions, as distances between stars in a galaxy are so vast.
Closest star to our sun is over 23,000,000,000,000 miles away.
Vehicles don’t fail to merge properly, drivers do.
Reminds me of another terminology curiosity.
When Parachutists hop out of an airplane they call it a jump, unless the chute fails and then it becomes a fall.
And pilots ask why anyone would jump out of a perfectly good airplane.
Black hole do actually merge – to form a single bigger black hole. The remnant of a neutron star collision may also result in a single black hole … as proposed for the collision that was observed.
Steve T – anywhere near St Cyprien?
Thank you Anthony and all contributors to WUWT. I have learnt so much over the years reading here. A happy Christmas to all and the very best for 2018.
And a Merry Christmas to you!
So wonderful to see settled science -at least as much as science can be-. We “saw” two neutron stars merge, according to the best of our tools and models, and even the consensus of our hard scientists. I can go with that. I can’t wait for the next 100/1000 years of this….. If only I had that many years. Can’t we please take all the money shoved down the global warming -wannabe- hole and task it to discover things like this.
Forget about consensus. Look at the epistemological situation. Read your Popper and then look at the evidence.
You don’t need to be a math or science guru to understand that if you can locate a celestial event with the new method and the old method, the new method is effective.
I have yet to see the “consensus” in sociological and climate sciences be able to predict their large complex systems to any degree of accuracy at all. A decent epistemological expert (e.g. Taleb) would tell you why, both from a common sense and mathematical standpoint.
Or you can go with the old standby – until some scientific idea is used to engineer a useful product, it’s probably not confirmed science. You don’t have to be a philosopher or scientist to make that kind of judgement.
Peter
Didn’t Willis put forward a theory that the validity of an article is inversely proportional to the number of authors? 4,156 authors if anyone who did significant analysis get a credit? That must set some sort of record.
(only partially being sarcastic – it seems like this would have been better as perhaps 40 or 50 papers about the individual analysis projects for each sensor pathway (still 100+ authors each!) and a good summary paper using all those as references.)
That is true in climate science, but not true concerning particle physics (CERN) or astrophysics as here.
Too bad we cannot get 535 Members of Congress to agree on anything.
I’ve wondered if the Sun felt the shaking. Its big enough to be a LIGO.
It’s not shaking its a space distortion and there is nothing about the sun that would function as a LIGO.The most common emitter of gravity waves is two bodies revolving in orbit about each. The earth-moon revolution is the strongest emission of gravity waves local to earth along with the tidal shift and LIGO has to filter them out. The Sun-Earth because of the distances and slower speed emits lower level gravity waves and much slower.
Since gravity waves are now confirmed you can consider it like resistance of space and all space orbitals are decaying as they are losing energy just very very slow via the gravity waves.
Hannes Alfvén might have an opinion if he were around today. The sun has strong Magnetic field lines thousands of miles long embedded in hot plasma. The structure of the deeper field lines may be more laminar. unlike those near the surface that become turbulent and chaotic. If that were the case it might take some weeks for the disturbance to reach the surface/photosphere.
Would not “two bodies revolving in orbit about each other” have a fairly stable centre of gravity? And their collision would not move this COG appreciably? Is it not possible that powerful gravitational events affect all mass in the Universe instantaneously, while a relatively slow “aftershock” travelling through the recently re-hypothesized ether at light speed could be measured by distant detectors millions of years later? Maybe we can have our cake and eat it too.
The other interesting aspect of being able to observe the light emitted by the merger of these two neutron stars is that the light contained the signature of many heavy elements.
The merger of neutron stars is a significant source of the heavy elements beyond iron/nickel. Supernova explosions also create these elements but neutron star mergers are also a significant source.
One can imagine two stars made-up mostly of neutrons held together by massive gravity (gravitational velocity is half of the speed of light at the surface of a neutron star). As they merge, material gets spun out and escapes the gravity. Instantly, unbelievable numbers of neutrons split into protons and electrons and unbelievable numbers of neutrons remain as a well.
The speed of this material at somewhere around half the speed of light or more is crashing into each other fusing neutrons and protons into giant atoms. The majority are highly radioactive and break apart in a millisecond, but what remains is the stable giant atoms/elements and the isotopes of those atoms/elements that can last for more than a millisecond. The majority of the isotopes are not stable in the long-run and eventually split apart until only the stable elements and isotopes remain, flying away at tremendous speeds..
These very large atoms and isotopes will contain some amount of uranium, platinum, gold and other heavy elements so this is one source for where the elements heavier than iron/nickel come from.
While some amount of material gets spun out in the merger, what is left behind is most likely a black hole. Neutron stars only have masses between 1.5 solar masses and about 3.0 solar masses. After 3.0 solar masses, gravity becomes so strong that it becomes a black hole. So, put two neutron stars together and the mass likely exceed the black hole limit.
So the merger created lots of heavy elements flying away at tremendous speed and a black hole. There are more than 1 billion neutron stars in the galaxy and lots of them have merged together in the past 12 billion years which means the galaxy has lots of heavy elements and lots of black holes.
Good info. The original cloud that formed our solar system must have had remnants of neutron-star collisions.
Actually, all elements beyond iron are not produced by main sequnce fusion. They are produced by supernova or by neutron star merger. And now we know that neutron star merger preferentially produces more very heavy (protons in neucleus) elements.
Bill, would this have created a burst of cosmic rays as some atoms are stripped of their electrons during ejection?
“Supernova explosions also create these elements but neutron star mergers are also a significant source.”
Supernovae create a surprisingly small number of the heavier elements. (see the white dwarf contributions on
https://upload.wikimedia.org/wikipedia/commons/3/31/Nucleosynthesis_periodic_table.svg)
Most heavier elements require explosions with more punch. Also interesting that boron and beryllium can not be produced by stellar nucleosynthesis – they are fission products of cosmic ray bombardment.
What if…. upon receiving our radio and TV transmissions… an alien civilization simply interprets them as cosmological phenomena? In order to prove this they would be compelled to build a ludicrously intricate model of spinning ferric objects careening around and off of each other. To speed it all up, maybe a clockwork of black holes and plasma tubes and quantum donuts of various sizes dancing in three dimensions cyclic on the pattern of some Golay Perfect Code so that it may provide a base carrier wave for aeonaeons, with various masses modulating the signal.
With some parabolic Dysonish reflector around it, that just happens to be focused in the direction of the alien civilization. As the waves come off the parabola the three dimensional model the waves combine to form the precise EM wave that matches the signal they received. Years of radio and TV transmissions. It’s a very complicated model but the aliens are meticulous and patient.
And perhaps… they manage to do this, but limitations of physics only permits them to build a slow moving model. It would (amazingly!) generate the proper waveform of the voices and music they ‘hear’ but do not perceive… explaining the nature of the wave completely. But they cannot make their model ‘work’ at the speed necessary to explain the high frequency waves they received.
So, in the end… to explain the high frequency… the aliens would be forced to conclude that this ponderously complex cosmological juggernaut was all traveling, at high and uniform velocity, directly towards them. It would raise a panic.
I can imagine them in a high state of anxiety, waving their pseudopods around.
Yeah, and if I ever finish my book about being kidnapped by aliens I will be a thousandaire.
Careful Hocus, someone may take this and run with it. It’s scarier than a fraction of a degree of warming per century and it would cost quadrillions to build a model to protect us from the coming invasion. Only lefties would buy into it but don’t forget a thoroughly corrupted broad got the majority vote (sorry, is this a legitimate diversity category? Being in the demographic that isn’t accepted into the diversity klatch, I haven’t had cause to sort it all out). Anyway, my point is that the majority of people have been moronized by substitution of independent thought by mindless talking points and Alinsky’s Rules.
https://www.steelonsteel.com/saul-alinskys-12-rules-for-radicals/
Read this link! You’ll thoroughly understand and recognize what we are up against.
As soon as they tuned into the 1950’s original I Love Lucy and the The Honeymooners broadcasts, they’d have known there was NO intelligent life here and they would’ve moved on. We were saved from alien colonization and extinction. Whew!! Dodged a bullet we did.
There’s GOLD in them thar collidin’ neutron stars. GOLD I tells ya. /crazy forty-niner mode
Half a planet’s worth, from one estimate based on the gold emission spectra.
Wonderful event, we’ll learn a lot from it and future ones.
Exciting stuff. Too bad there isn’t a way to get to watch the event before the aftermath. Do the gravity waves only develop at the point of collision or are their very low frequency waves generated in advance. It would seem logically, that as the bodies approached, you would begin to get perturbations that would generate gravity waves unless it happens with the massive destruction of matter on collision. Is this stuff too new to know about?
Read up on this at the time of the first black hole detection. We are limited by LIGO sensitivity. So it is only as the two objects orbiting each other get very close at a very high spin rate (figure skater spin analogy, just conservation of momentum) that we can detect the gravity waves produced.
It is only in the last several seconds before merger that the wave amplitudes are strong enough detect at megaparsec distances. So time-wise, the gravity waves arrived at LIGO, then a second or so later (when the physical merger occurred) the GRB flash arrived at Earth. A one-two punch. Then the optical guys get alerted and start hunting it down to record the light decay curves.
Maybe Granit from upthread can answer your questions Gary, since Granit finds us so comically naive…
Science is based on measurements and observations; neither of two are exact, but are only approximations of the reality, thus as such are likely to be wrong in some extent.
Knowing the extent of ‘how much wrong’ is the essence and beauty of the good science.
From the original report at physicsworld.com:
“The gravitational-wave signals were measured for about 100 s, whereas those from previous black-hole mergers lasted less than about 1.5 s. This longer measurement time reduced the uncertainty in the location of the merger, while the shape of the signal allowed astronomers to estimate the masses of the neutron stars to be about 1.1 to 1.6 solar masses. The amplitude of the signal gives the distance to the source to within a 30% margin of error.
High-energy gamma rays from GW170817 were detected in the form of a short burst, some 2 s after the gravitational waves. Astronomers had suspected that such bursts are caused by neutron-star mergers, but had little understanding of how it happens. “We confirmed that colliding neutron stars power short gamma-ray bursts, solving one of the greatest mysteries in present-day high-energy astrophysics,” says Francesco Pannarale of the University of Cardiff in the UK.
The prompt arrival of the gamma-ray signal also confirms that gravitational waves travel at the speed of light, while the ability to observe light and gravitational waves arriving from distant objects will allow physicists to perform more stringent tests of Einstein’s general theory of relativity.”
Nice to see that Kenji shares his materials with Anthony. Happy holidays to all.
Happy pre-holidays everyone…:)
Sorry lads, boyz and girlz, but this is ‘a bit poor’ Must try harder.
Are there 100 billion stars in our galaxy?
Stars last how long? Maybe 10 billion years then go (supernova) bang.
So we get 10 bangs per year in our galaxy
Now, get a 10 pence piece (is a dime about the same size) and hold it at arms length up at the sky so it blots out a circular piece of sky. Any direction you like.
There are 100,000 galaxies behind that dime.
Thence 1 million supernovae, annually, behind the dime. 100 per day?
(Maybe devise a ‘holding contraption’ for the dime – gonna get crippling arm-ache otherwise. Jam it in a tree or something.)
S’pose we’re left wondering how many supernova leave neutrons behind and how many are close enough or get the inclination to merge but, something tells me that, across the whole sky, it’s gonna be more than one every 2 years……….
Pete, quite right, but Mother Nature does not respect your calculations.
Here’s a link to the LIGO event fact sheet:
http://www.ligo.caltech.edu/system/avm_image_sqls/binaries/99/original/GW170817_Factsheet.jpg?1508114118