The sign of a great teacher, is being able to explain things, to different students, in the way the student learns and understands. And he makes it exciting, bonus.
@@garrysekelli6776 He's guessing, it's a theory he's working with. Great teachers can open your mind to new possibilities, I never take it as fact, because they don't know enough yet. But they can inspire others to think in new directions, even prove them wrong. I like to hear all ideas and theories.
@@spazmobot well that's a complete cop out. I mean like mate: either it's real or it isn't real. So what you are saying is that cause what this guy is saying is so revolution ary that we need to revamp our entire society.
This is what science is about. The way the professor humbly accepts that his theory is out based on new data, and is not married to an idea but knows to look at things in a factual way, is what we need more of in our society today.
Really enjoy listening to Copeland explain. Please tell him we want even more with him! (that does NOT mean we want less of the other wonderful professors)
I could listen to Ed talk for hours and hours. I've listened to his previous interviews on this channel many many many times now. Having a new one to listen to, and on such an exciting topic, has made my whole week better.
I went to UoN and Ed was my lecturer for a couple of modules. His voice is so soothing, it's dangerous for those early morning lectures. It was like being read the most fascinating bedtime story.
This is one of my favorite channels. I love how you can break these complex things down into simple language. I have learned so much about physics from watching you and some others, and I hope I can get around to learning the kinds of maths to understand this stuff better one day.
So glad to see another fantastic Prof. Copeland video. He has such a great gift for explaining and expressing the wonder of these incredibly complex physical phenomenon to us amateur arm-chair particle physicist , like myself. Thanks Prof!
17:07 the frequency signature (the particular sound) of an musical instrument can be recognized regardless of the amplitude of the signal, as long as it's at least partially above the noise floor. a violin and a trumpet playing the very same note are quite distinguishable from each other even at low SPL (different amplitudes for different harmonics). to take it farther, even just by ear, we can recognize the voice of someone familiar to us if they're whispering or talking over a poor quality phone connection. w/ a lot of data missing, a pattern/ the voice signature can still be recognized. that's how i understand analyzing the faint gravitational wave signals.. :} another great upload, thanks to everyone involved. truly enjoyable, wishing you all all the best.
Prof. Copeland is my personal favourite in the line-up for sixty symbols. They're all great, the bar is high. But it's just that I feel a little bit more humbled when, through your videos, I get the opportunity to sit down with this wise and calm professor.
I'm so glad that after watching these Sixty Symbols uploads for years they're popping out new stuff building on old stuff - it's like watching science in action!!! Who'd have thunk it?
On the Hubble tension at 16:10: "As long as you can pinpoint how far away the object is and the polarization of the light, then actually, the expansion rate of the universe will pop out. It will come out. It will be a direct measurement." I wish Prof. Copeland could expand on that in a future video. I would love more information on how measuring the properties of these mergers can reveal the Hubble constant, and why this method is not constrained in the same way that the study of the CMB or supernovae would be.
I'm guessing how fast the universe is expanding will shift the light coming in, changing its wavelength. If you know the distance, you can measure the change in wavelength and determine the expansion required to result in that change.
That's one of the ways we measure the expansion rate today. We use type 1A supernovae, which always explode when they reach the same critical mass, so they can be used as a so-called "standard candle" throughout the universe because they are believed to always explode with the same luminosity (I read somewhere recently that there may be outliers in that data, but we can ignore that for now). We use that in combination with redshift to get one value for the Hubble constant. My naïve understanding of the way we would perform this measurement with gravitational waves would be to derive the original energy of the collision, then measure that against the energy received to understand distance from us. Beyond that, every popular explanation I've read has been too hand-wavy to get anything meaningful out of it. The way I interpret Prof. Copeland's words at 15:53 is that there is something intrinsic in that data that is not in the supernova data that could give a definitive answer, and that's what I'd really like to dig into. At 15:53, he says that the supernova and CMB data "rely on you understanding the cosmology of the system". And I totally get that for the CMB -- our understanding of the Hubble constant relies on our understanding on the CMB. I'm less sure why that is for supernova data, but regardless, I'd love to understand why all of the necessary data is self-contained in the gravitational wave signal.
@@tedsword there is still a chance the expansion is not uniform over time and or space. It was only 2 years ago that the accepted shape of our heliosphere changed (dramatically)!
My confusion is not about /why/ they are measuring it -- I'm sure that telescope time has been proposed with the James Webb Space Telescope, as well, to measure the Hubble constant, as well. My confusion is that Prof. Copeland seemed to indicate that there is something about the gravitational wave signal that doesn't have a dependency on "the cosmology of the system", as he put it. But I don't see how the study of cepheid variables, type 1A supernovae, and other techniques to derive the Hubble constant have a dependency, either. I don't know what makes the gravitational waves technique more special.
I really appreciate follow up videos like this. When the first detection took place, all the talk was about how this would open up the field of gravitational astronomy. It's so interesting to see now how it is starting to contribute to the field 🙏
Just an extra thing to add to the theories of formation, crucially we can measure how misaligned the spins are. If you imagine the BHs have a spin vector pointing up out of its axis of rotation, and similarly for the total angular momentum of the orbit, the angle between these vectors (tilt) can be measured using the LIGO data. We generally measure quantities that are dependent on tilt, not tilt itself because it's very difficult to directly measure. Misalignment and magnitude of the spins are important characteristics of different formation channels as they are called.
As I've gotten older, I've noticed a really weird thing. I'm getting....jealous...of people just being born. Imagine... I was born mid-70's and in JUST MY ONE LIFETIME, we've gone from launching the Voyager probes to contemplating and working towards an actual moon base. My mind just weeps at what is going to come once I've gone. AND I'm GOING TO MISS OUT ON ALL OF IT!!! -_- Thanks for the amazing video, as always :)
I think that Dr. Copeland is one of my favorite academics to listen to. When I hear him explain a topic, it makes me wish I had gone into theoretical cosmology so I could have collaborated with him.
Great video. Questions If you are on a planet that's let's say 2 light years away from 2 merging black holes. And say you do survive the radiation and all that, what would the gravity wave be like when it passes by?
Copeland's explanation of how a simple set of data points backed by complex modeling and well verified theories can produce so much information, is the stuff I love most about this type of science. Evolution (which I did) works the other way, you have a simple theory that leads to very complex data.
Does this suggest that once we develop sufficiently sensitive detectors, there will be infinitely many signals detected? I'm imagining a constant white noise of low amplitude gravitational waves, with ocasional, or maybe periodic, higher amplitude events.
Great stuff! Is there actually any explanation for even the minuscule 1.7s second difference in arrival time of the electromagnetic and gravitational waves?
Assuming the light was slower than the gravitational waves (because I don’t think they explicitly said so) I’d say smth like interstellar dust slowing down the X-rays. Space isn’t a perfect vacuum so it’ll slow the light down a little bit like any other medium.
When two neutron stars merge, they throw off neutronium in an excretion disk, which then decompresses and splits into heavy nuclei. Maybe it's the time it takes to form nuclei and electrons from throw-off neutronium.
My understanding is that it's a difference in when they're emitted. Different phases of the mergers are producing the electromagnetic and the gravitational waves, since the gravitational waves are produced leading up to the two objects actually making contact, but the light is (presumably) produced most brightly at the actual moment of contact.
Interesting way of thinking about the relationship of strong gravity and small black holes. I read somewhere that the forces will be so weak for supermassive black holes that you won't even feel anything noticeable when you pass the event horizon.
With three (or more) synchronized observatories, we would be able to triangulate the spatial origin of each event, right? This could be compared to the direction of the X-ray burst.
Yes. This is exactly what happened with the event in 2017 they referenced with the gamma ray burst coupled with gravitational waves. Three detectors triangulated a position and Fermi detected the gamma rays 1.7 s later.
14:24 Despite the merged event horizons, you can actually tell by the still perturbating (perturberating ?) lensing, that even though the event horizons have already become one, the orbits around each other's center is still happening for at least 6 or 7 more orbits, but after that settles, there's no more, which means that the cores have now made contact. this then allows for actually telling the size of the cores. Now if there were also other types of detection on this particular event, which would maybe show an expression or outburst of high gamma particles, or a plasma stream starting to go outward, that would have been nice too. These could then be played simultaneously, with the timing synchronized by their center motion timing. If only that video cut was a little longer., because even at the end of it there was still motion in the lensing.
At 22:00 a journal editor was quoted as saying the Beatles made only "limited contributions to cosmology." I would argue that the Beatles song "Across the Universe" is a significant contribution. Words are flowing out like endless rain into a paper cup They slither wildly as they slip away across the universe Pools of sorrow, waves of joy are drifting through my opened mind Possessing and caressing me
I never quite got how the mirror displacement measure isn't canceled by the light also conforming to spacetime bending, ie the mirror and light inside the spectrometer arm should deviate the same, so no net difference.
I haven't done the calculation myself, but it's probably not too hard, at least in a weak-field approximation, to calculate how the phase of the light wave at the detector changes depending on the current stretching or contracting of the space along the arm. They then probably work backwards from that to get the gravitational wave amplitude.
The 'trick' here is that the light doesn't behave that way. If gravitational waves just changed 'distance' there'd be no way for them to interact at all, they'd be totally undetectable. Fortunately for us their warping of space affects some things but not others. (This is amusingly known as the 'Sticky Bead Argument') Roughly stated, the mirrors notice the change but the light between them doesn't.
I love all of the channels that Brady and the team create. How far in advance of a merger does LIGO detect the merger? Is this a detection only within the last few seconds prior to merger?
Guys, can you do something about the sound volume on future videos, please? I watch TH-cam on my laptop and for softer-spoken interviewees it is sometimes hard to hear them, even at my max volume. A pity since Prof. Copeland has interesting things to convey.
8:05 The x-rays that arrived 'late' had sleight bends to them by gravity source, except for the ones that were from the source adding a sleight bending to them increasing their path length by 510.000 over the distance of 300.000.000 LY. The greater the frequency of the detection method the less bending, unlike light, which may also have been capturable a few minutes or even hours later, dependant on the amount of bending added. It would be neat to have a full dataset on a phenomenon, ranging from gravitic to gamma, to light, to radio, etc. The more there is the less speculation and less "I wish we had .as well" 9:06 You were right expecting that the different detection methods yield different ATA's., except that the difference was really small for x-ray vs. gravitic, but did you also check for gravitic vs. light ?
What happens to the accretion disks when black holes merge? One naked black hole or an accretion disk with a portion of the source AD masses? Are a portion of the AD masses ejected and at what velocities?
Bradyons just means slow particles, I.E not travelling at C, meaning they have a real, positive mass, as opposed to tachyons, which have an imaginary mass and thus cannot travel below C. All stars are bradyon stars in that they're made of matter that is not travelling at C.
What I want to know if how does ligo differentiate local space time distortion due to earth dynamics and the solar system, and these miniscule black hole signals. It'd be interesting to see a detailed video on that.
14:38 If a black hole has significant spin, it's the result of a large scale merger, since that merger itself preserves some of the motion in the spin, with a high degree of certainty. If it has little, it probably never merged with something similar sized. The spin is the result of two objects similar in size and mass, that orbit each other before merger. If no such orbit happens, it means that the object it merges with simply crashed close to the center, and leaves very little spin. Basically guaranteed spin is similar sized black holes merging after orbiting around a common center outside of both black hole's event horizons.
Joke. Two black holes merge to create a new bigger black hole. What did they do when I tried to peek ? They closed their event horizons saying "u-p-erv."
With interferometry or any other kind of destructive interference - where does the "destructive" energy go? Into the constructive part (does it always exist). Since energy is conserved. If gravitational waves distort spacetime, how do they effect space different to light? Isn't light in said space and time.
Can gravitational waves pass through a black hole, or are they swallowed? If they pass, would this not mean, that within the BH can be produced gravitational waves which leave the BH and thus pass information to the outside of the event horizon? Especially in large black holes this would technically possible, since they do not spaghettify.
@@nmarbletoe8210 I once found an answer somewhere, stating that no, they don't pass through the black hole. Which is explicable, since the amplitude of the gravitational wave is always very small compared to the huge gravity of the BH. I don't remember the details, whether it is reflected or absorbed. But maybe the wave behaves similar to a water wave encountering a vertical pole in the water. The pole surface might be corresponding to the event hotizon.
@@rex_rabbit Cool cool cool! A photon can't fall into a black hole if it's wavelength is bigger than the hole's radius! So I read. Maybe it's the same with grav waves. They get absorbed if their wavelength is smaller than the diameter of the hole, other wise they refract. And if they the wavelength is much much longer than the diameter, they basically pass by the hole little effect since the refraction gets smoothed out.
can we please have a video of prof. Copeland talking about "pulsar network gravitational wave observatory" and how it might relate to his work on cosmic super strings
How do they resolve the vibrations on the atoms in the mirror itself? It seems like at that scale those would be much greater than the gravitational event.
In this spectrogram at 17:16 are in the background artifacts visible, that look like weak versions of the collision curve. Are those artifacts from template matching?
No, they're other events occurring in the detector, vibrations from traffic, micro-earthquakes and the like. You'll notice they're slightly different in each spectrum, they don't match and can be discarded.
20:03 At LIGO they create raw data by measuring gravitional differences. This is filtered, so only the usable part remains using high powered data crunching computers. The timing difference in the both data streams gives an angle at which this overlap occurs. That means that with such an overlap you know can plot a line towards the phenomenon from Earth. The scrubbed data can then be interpreted with the variations, and now you know of large masses in motion with the vibrations showing an orbit, which correlates with the freqency of those deviations. They are orbitting, but also their mass sizes, their speed, their distance from one another. Then you let the thing play out, and from the motion you can now re-create a 3D model, which accurately shows both objects in motion, despite both's event horizons. When this data is merged with other types of detection and synchronized, you can then also tell the size of the event horizon, and by overlaying the trajectories of the objects you can also see motion through the lensing effects, that may occur just that bit longer than the sensitivity of the gravimetrics have reached their limit and thus tell you the physical dimension or at least get a close approximation of such, with greater detail than current gravimetrics allow. This all then is achieved through Multi-Messenger Astronomy which combines or cooperates in such a fashion that all possible data that can be collected also is collected, emphasis is, and also is collimated into one single data source, which subsequently tells a whole lot more than just a single data source about said phenomenon. Once the full array of data collectors (telescopes) are in play you'd ahve more than enough data to make very intricate conclusions on just about anything happening in the Universe, after watching a few events, which then harden as predictions either get proven or disproven upon repeated observation. That is explorative astrophysics at it's very finest.
I have a question. Why don't grav waves interfere with each other as they travel? How do we know that what we get here is a single ripple from a single event, and not actually the combination of an infinite number of grav wave events? Would 1 grav wave survive if another collision happened on the path between it and us? Wouldn't this kind of scenario mean you can't reverse engineer the size of the black holes of a single event? What am I missing?
They pass through each other just like light does. In fact, water waves also do that as long as they are small waves. As soon as waves start to foam or crest, they can splash and lose energy instead of passing easily through each other. Gravity waves don't crest or splash I guess!
Does black holes have north and south poles? Does angle between axis of rotation of colliding black holes make the difference? (should I be worry about it?)
Hello Dr. Copeland as you mention the Hubble tension have you read the paper "A Test of the Cosmological Principle with Quasars" (Nathan J. Secrest et al 2021 ApJL 908 L51)? The paper performs a experimental test of the Kinematic dipole assumption proposed in the 1980's and the large sample size of 1.36 million distant quasars has some very serious implications for our standard cosmological assumptions effectively falsifying the validity of the kinematic dipole assumption and thus in turn falsifying the cosmological principal by showing that the CMB dipole contains a significant nonzero cosmological component of some kind. The findings have a statistical significance of 4.9 sigma deviation from the predictions of a kinematic dipole or a 1 in 2 million chance of being a statistical fluke. This might be enough to clean up the Hubble tension due to the large systematic bias that any model with the cosmological principal assumption built in. Never forget about systematic bias!
The description of receiving a "chirp" and then correlating/comparing it to templates sounds a lot like how modern radars work, so the principle makes sense. But in this case, the signal levels involved are staggeringly minute!
Say we know exactly where to look in the sky at the same exact time we detect a meger, can we visibly see the evidence of a said merger (via supernova type explosion or astrophysical jet type deal) at the same time we detect them? Since the visible light and gravitational waves travel at the same speed.
I can never get enough of prof. Copeland's enthusiasm and he does such a great job at trying to explain complex matters to the masses.
The sign of a great teacher, is being able to explain things, to different students, in the way the student learns and understands. And he makes it exciting, bonus.
He's wrong though cause black holes and gravitational waves don't exist. Pure fantasy from heads like these .
@@garrysekelli6776 right on
@@garrysekelli6776 He's guessing, it's a theory he's working with. Great teachers can open your mind to new possibilities, I never take it as fact, because they don't know enough yet. But they can inspire others to think in new directions, even prove them wrong. I like to hear all ideas and theories.
@@spazmobot well that's a complete cop out. I mean like mate: either it's real or it isn't real. So what you are saying is that cause what this guy is saying is so revolution ary that we need to revamp our entire society.
I love listening to Professor Copeland explaining these things.
Always a pleasure.
Really wish I could find some extended lectures of his.
This is what science is about. The way the professor humbly accepts that his theory is out based on new data, and is not married to an idea but knows to look at things in a factual way, is what we need more of in our society today.
true!
Well, you know, that's just the universe's opinion on the matter... ;-)
/s
This has to be one of the longest, yet simplest, explanation of the most exciting new field of Science! I mean…I could’ve listened all day!
Really enjoy listening to Copeland explain.
Please tell him we want even more with him!
(that does NOT mean we want less of the other wonderful professors)
Professor Ed Copeland for the win my absolute favorite professor
I could listen to Ed talk for hours and hours. I've listened to his previous interviews on this channel many many many times now. Having a new one to listen to, and on such an exciting topic, has made my whole week better.
I went to UoN and Ed was my lecturer for a couple of modules.
His voice is so soothing, it's dangerous for those early morning lectures. It was like being read the most fascinating bedtime story.
@@scottrobinson4611
Oh man that's luxurious and dangerous in double measure. I, not a morning person by any measure, would be utterly doomed.
Happy to see Proffesor Copeland again!
This is one of my favorite channels. I love how you can break these complex things down into simple language. I have learned so much about physics from watching you and some others, and I hope I can get around to learning the kinds of maths to understand this stuff better one day.
So glad to see another fantastic Prof. Copeland video. He has such a great gift for explaining and expressing the wonder of these incredibly complex physical phenomenon to us amateur arm-chair particle physicist , like myself. Thanks Prof!
17:07 the frequency signature (the particular sound) of an musical instrument can be recognized regardless of the amplitude of the signal, as long as it's at least partially above the noise floor. a violin and a trumpet playing the very same note are quite distinguishable from each other even at low SPL (different amplitudes for different harmonics).
to take it farther, even just by ear, we can recognize the voice of someone familiar to us if they're whispering or talking over a poor quality phone connection. w/ a lot of data missing, a pattern/ the voice signature can still be recognized. that's how i understand analyzing the faint gravitational wave signals.. :}
another great upload, thanks to everyone involved. truly enjoyable, wishing you all all the best.
i'm a musician and i can't believe i didnt make this comparison, thanks. though i'm a performer, not a sound engineer lol
Prof. Copeland is my personal favourite in the line-up for sixty symbols. They're all great, the bar is high. But it's just that I feel a little bit more humbled when, through your videos, I get the opportunity to sit down with this wise and calm professor.
I'm so glad that after watching these Sixty Symbols uploads for years they're popping out new stuff building on old stuff - it's like watching science in action!!! Who'd have thunk it?
Never knew our man Ed was a collar up kinda guy. Thanks for yet another fascinating video!
Ed is the man bro
Collar up is the only way to rock a polo neck!
Professor Copeland is such a great guy :) Always a joy to listen to.
I love listening to Ed talk about stuff. The twinkle in the eye when he's excited about something, it's so charming.
On the Hubble tension at 16:10: "As long as you can pinpoint how far away the object is and the polarization of the light, then actually, the expansion rate of the universe will pop out. It will come out. It will be a direct measurement."
I wish Prof. Copeland could expand on that in a future video. I would love more information on how measuring the properties of these mergers can reveal the Hubble constant, and why this method is not constrained in the same way that the study of the CMB or supernovae would be.
I'm guessing how fast the universe is expanding will shift the light coming in, changing its wavelength. If you know the distance, you can measure the change in wavelength and determine the expansion required to result in that change.
That's one of the ways we measure the expansion rate today. We use type 1A supernovae, which always explode when they reach the same critical mass, so they can be used as a so-called "standard candle" throughout the universe because they are believed to always explode with the same luminosity (I read somewhere recently that there may be outliers in that data, but we can ignore that for now). We use that in combination with redshift to get one value for the Hubble constant.
My naïve understanding of the way we would perform this measurement with gravitational waves would be to derive the original energy of the collision, then measure that against the energy received to understand distance from us. Beyond that, every popular explanation I've read has been too hand-wavy to get anything meaningful out of it.
The way I interpret Prof. Copeland's words at 15:53 is that there is something intrinsic in that data that is not in the supernova data that could give a definitive answer, and that's what I'd really like to dig into. At 15:53, he says that the supernova and CMB data "rely on you understanding the cosmology of the system". And I totally get that for the CMB -- our understanding of the Hubble constant relies on our understanding on the CMB. I'm less sure why that is for supernova data, but regardless, I'd love to understand why all of the necessary data is self-contained in the gravitational wave signal.
@@tedsword there is still a chance the expansion is not uniform over time and or space. It was only 2 years ago that the accepted shape of our heliosphere changed (dramatically)!
My confusion is not about /why/ they are measuring it -- I'm sure that telescope time has been proposed with the James Webb Space Telescope, as well, to measure the Hubble constant, as well.
My confusion is that Prof. Copeland seemed to indicate that there is something about the gravitational wave signal that doesn't have a dependency on "the cosmology of the system", as he put it. But I don't see how the study of cepheid variables, type 1A supernovae, and other techniques to derive the Hubble constant have a dependency, either. I don't know what makes the gravitational waves technique more special.
Sixty Symbols is one of the very best science news here on TH-cam.
Professor Copeland is my favorite on this channel, I can listen to him for hours!
Always a pleasure to see prof Copeland
I could listen to Professor Copeland for hours ...popped collar and all. ;)
I do love it when you've been rewatching sixty symbols videos for the umpteenth times and a new one pops up 😊.
This is absolutely amazing, I love professor Copeland!!
Copeland has such a calmness. It has always struck me as a lovely presence.
Tis guy is truly incredible. Wish I'd have had a single Prof like that.
I really appreciate follow up videos like this. When the first detection took place, all the talk was about how this would open up the field of gravitational astronomy. It's so interesting to see now how it is starting to contribute to the field 🙏
Just an extra thing to add to the theories of formation, crucially we can measure how misaligned the spins are. If you imagine the BHs have a spin vector pointing up out of its axis of rotation, and similarly for the total angular momentum of the orbit, the angle between these vectors (tilt) can be measured using the LIGO data. We generally measure quantities that are dependent on tilt, not tilt itself because it's very difficult to directly measure. Misalignment and magnitude of the spins are important characteristics of different formation channels as they are called.
Professor Copeland is just an amazing person!
Ed is back. Will be a happy watch later.
This is a fascinating video, I'm very excited to see future follow up video on this subject in the years to come!
Would love a video going over how another Hubble constant measurement pops out of these multimessenger measurements.
Excellent interview and very insightful questioning. Well done.
As I've gotten older, I've noticed a really weird thing. I'm getting....jealous...of people just being born.
Imagine...
I was born mid-70's and in JUST MY ONE LIFETIME, we've gone from launching the Voyager probes to contemplating and working towards an actual moon base. My mind just weeps at what is going to come once I've gone. AND I'm GOING TO MISS OUT ON ALL OF IT!!! -_-
Thanks for the amazing video, as always :)
Ed! Glad you guys a posting again
I think that Dr. Copeland is one of my favorite academics to listen to. When I hear him explain a topic, it makes me wish I had gone into theoretical cosmology so I could have collaborated with him.
I love prof. Copeland. Literally love the man.
Great video. Questions If you are on a planet that's let's say 2 light years away from 2 merging black holes. And say you do survive the radiation and all that, what would the gravity wave be like when it passes by?
absolutely phenomenal work, amazing explanation
this is my favoritest physicks professor
Copeland's explanation of how a simple set of data points backed by complex modeling and well verified theories can produce so much information, is the stuff I love most about this type of science. Evolution (which I did) works the other way, you have a simple theory that leads to very complex data.
Great video as always, fascinating stuff ! Video explaining the engineering behind LIGO would be amazing !
Gosh! This is so amazing! When he explains it, he makes it look so simple.
Does this suggest that once we develop sufficiently sensitive detectors, there will be infinitely many signals detected? I'm imagining a constant white noise of low amplitude gravitational waves, with ocasional, or maybe periodic, higher amplitude events.
Great stuff!
Is there actually any explanation for even the minuscule 1.7s second difference in arrival time of the electromagnetic and gravitational waves?
Assuming the light was slower than the gravitational waves (because I don’t think they explicitly said so) I’d say smth like interstellar dust slowing down the X-rays. Space isn’t a perfect vacuum so it’ll slow the light down a little bit like any other medium.
When two neutron stars merge, they throw off neutronium in an excretion disk, which then decompresses and splits into heavy nuclei. Maybe it's the time it takes to form nuclei and electrons from throw-off neutronium.
My understanding is that it's a difference in when they're emitted. Different phases of the mergers are producing the electromagnetic and the gravitational waves, since the gravitational waves are produced leading up to the two objects actually making contact, but the light is (presumably) produced most brightly at the actual moment of contact.
maybe the gravitatioal waves got slowed down due to all the matter in their path bending space-time?
These presentations are superb well done
Beautiful visualization of how LIGO works!
Sometimes I feel that the engineers and experimentalists don't receive enough credit.
Theorists gather more attention because is easier to make headlines.
*No credit besides salary. But isn´t that in most of society?
Interesting way of thinking about the relationship of strong gravity and small black holes. I read somewhere that the forces will be so weak for supermassive black holes that you won't even feel anything noticeable when you pass the event horizon.
Fantastic explanation. Inspirational!
I Need a prof Copeland in my life. I can listen hours to this man.
This is breathtakingly fascinating. Thank you for sharing this with us!
Amazing! I always love the way he explains things. I could've listened for hours
With three (or more) synchronized observatories, we would be able to triangulate the spatial origin of each event, right? This could be compared to the direction of the X-ray burst.
Yes. This is exactly what happened with the event in 2017 they referenced with the gamma ray burst coupled with gravitational waves. Three detectors triangulated a position and Fermi detected the gamma rays 1.7 s later.
@@jeffk8019 Ah, I see.. I thought the third one became operational only recently.
14:24 Despite the merged event horizons, you can actually tell by the still perturbating (perturberating ?) lensing, that even though
the event horizons have already become one, the orbits around each other's center is still happening
for at least 6 or 7 more orbits, but after that settles, there's no more, which means that the cores have now made contact.
this then allows for actually telling the size of the cores.
Now if there were also other types of detection on this particular event, which would maybe show an expression or
outburst of high gamma particles, or a plasma stream starting to go outward, that would have been nice too.
These could then be played simultaneously, with the timing synchronized by their center motion timing.
If only that video cut was a little longer., because even at the end of it there was still motion in the lensing.
This video left me wondering: do gravitational waves get "red shifted"?
When bh’s collide, is the information in the mass loss from the coalesced bh’s encoded in the gw’s?
I missed Ed. Very glad to see him back.
17:07 "How can we infer so much from such a tiny signal?" Thanks for asking this question!!
At 22:00 a journal editor was quoted as saying the Beatles made only "limited contributions to cosmology." I would argue that the Beatles song "Across the Universe" is a significant contribution.
Words are flowing out like endless rain into a paper cup
They slither wildly as they slip away across the universe
Pools of sorrow, waves of joy are drifting through my opened mind
Possessing and caressing me
I'm a simple man, I see Ed Copeland on the thumbnail, I click.
I never quite got how the mirror displacement measure isn't canceled by the light also conforming to spacetime bending, ie the mirror and light inside the spectrometer arm should deviate the same, so no net difference.
I haven't done the calculation myself, but it's probably not too hard, at least in a weak-field approximation, to calculate how the phase of the light wave at the detector changes depending on the current stretching or contracting of the space along the arm. They then probably work backwards from that to get the gravitational wave amplitude.
The 'trick' here is that the light doesn't behave that way. If gravitational waves just changed 'distance' there'd be no way for them to interact at all, they'd be totally undetectable. Fortunately for us their warping of space affects some things but not others. (This is amusingly known as the 'Sticky Bead Argument') Roughly stated, the mirrors notice the change but the light between them doesn't.
its not the mirror that is effected it is the length of the legs/arms, the observatory is JUST continuously measuring the change in their length.
I love all of the channels that Brady and the team create. How far in advance of a merger does LIGO detect the merger? Is this a detection only within the last few seconds prior to merger?
Amature question here, have the detections at Ligo led to them being able to calculate the elasticity of spacetime itself?
Guys, can you do something about the sound volume on future videos, please? I watch TH-cam on my laptop and for softer-spoken interviewees it is sometimes hard to hear them, even at my max volume. A pity since Prof. Copeland has interesting things to convey.
8:05 The x-rays that arrived 'late' had sleight bends to them by gravity source, except for
the ones that were from the source adding a sleight bending to them increasing their
path length by 510.000 over the distance of 300.000.000 LY.
The greater the frequency of the detection method the less bending, unlike light,
which may also have been capturable a few minutes or even hours later,
dependant on the amount of bending added.
It would be neat to have a full dataset on a phenomenon, ranging from gravitic to gamma, to light, to radio, etc.
The more there is the less speculation and less "I wish we had .as well"
9:06 You were right expecting that the different detection methods yield different ATA's., except
that the difference was really small for x-ray vs. gravitic, but did you also check for gravitic vs. light ?
What happens to the accretion disks when black holes merge? One naked black hole or an accretion disk with a portion of the source
AD masses? Are a portion of the AD masses ejected and at what velocities?
We love Ed!
Mr. Ed, your ability to explain these incredibly complex ideas sets you apart. While maybe not to Feinman’s level but close!!
Awesome. I get graced with a fantastic sixty symbols video.
Thank you for what you do.
1:20 is there detectible frequency of those mergers ? Do we detect more and more or les and less or is it a steady rate of detections ?
Great answers and great questions, as always.
3:01 "the lesbians bounce off the mirrors"
Bradyons just means slow particles, I.E not travelling at C, meaning they have a real, positive mass, as opposed to tachyons, which have an imaginary mass and thus cannot travel below C. All stars are bradyon stars in that they're made of matter that is not travelling at C.
Isn't that (LIGO) the same setup as the old Michaelson-Morely experiment?
What I want to know if how does ligo differentiate local space time distortion due to earth dynamics and the solar system, and these miniscule black hole signals. It'd be interesting to see a detailed video on that.
Great questions and answers! Thank you.
14:38 If a black hole has significant spin, it's the result of a large scale merger,
since that merger itself preserves some of the motion in the spin, with a high degree of certainty.
If it has little, it probably never merged with something similar sized.
The spin is the result of two objects similar in size and mass, that orbit each other before merger.
If no such orbit happens, it means that the object it merges with simply crashed close to the center,
and leaves very little spin.
Basically guaranteed spin is similar sized black holes merging after orbiting around a common center
outside of both black hole's event horizons.
Joke.
Two black holes merge to create a new bigger black hole.
What did they do when I tried to peek ? They closed their event horizons saying "u-p-erv."
Love Prof Copeland
I know you aren't looking for them, but would an alcubierre drive leave an unusual gravitational wake that LIGO might be able to identify?
With interferometry or any other kind of destructive interference - where does the "destructive" energy go? Into the constructive part (does it always exist). Since energy is conserved.
If gravitational waves distort spacetime, how do they effect space different to light? Isn't light in said space and time.
The destructive interference prevents the energy transfer before it can occur.
Can gravitational waves pass through a black hole, or are they swallowed?
If they pass, would this not mean, that within the BH can be produced gravitational waves which leave the BH and thus pass information to the outside of the event horizon?
Especially in large black holes this would technically possible, since they do not spaghettify.
please someone answer this question it's awesome!
@@nmarbletoe8210 I once found an answer somewhere, stating that no, they don't pass through the black hole. Which is explicable, since the amplitude of the gravitational wave is always very small compared to the huge gravity of the BH.
I don't remember the details, whether it is reflected or absorbed. But maybe the wave behaves similar to a water wave encountering a vertical pole in the water. The pole surface might be corresponding to the event hotizon.
@@rex_rabbit Cool cool cool! A photon can't fall into a black hole if it's wavelength is bigger than the hole's radius! So I read.
Maybe it's the same with grav waves. They get absorbed if their wavelength is smaller than the diameter of the hole, other wise they refract.
And if they the wavelength is much much longer than the diameter, they basically pass by the hole little effect since the refraction gets smoothed out.
@@nmarbletoe8210 Nevertheless, keep in mind that photons are attracted by gravitation, while gravity waves are not.
@@rex_rabbit Actually I'd expect that they would both follow null geodesics... idk
What a wonderful man. Brilliant.
I find it impossible not to love Prof. Copeland (I'm not trying mind you).
Clicked fast on this one. Great vid!
can we please have a video of prof. Copeland talking about "pulsar network gravitational wave observatory" and how it might relate to his work on cosmic super strings
How do they resolve the vibrations on the atoms in the mirror itself? It seems like at that scale those would be much greater than the gravitational event.
I can't pass up a video with Professor Copeland in the thumbnail.
Yeah!
the person in the thumbnail is the biggest deciding factor of whether or not I'll be clicking on the video in question
false.
In this spectrogram at 17:16 are in the background artifacts visible, that look like weak versions of the collision curve. Are those artifacts from template matching?
No, they're other events occurring in the detector, vibrations from traffic, micro-earthquakes and the like. You'll notice they're slightly different in each spectrum, they don't match and can be discarded.
20:03 At LIGO they create raw data by measuring gravitional differences.
This is filtered, so only the usable part remains using high powered data crunching computers.
The timing difference in the both data streams gives an angle at which this overlap occurs.
That means that with such an overlap you know can plot a line towards the phenomenon from Earth.
The scrubbed data can then be interpreted with the variations, and now you know of large masses in motion
with the vibrations showing an orbit, which correlates with the freqency of those deviations.
They are orbitting, but also their mass sizes, their speed, their distance from one another.
Then you let the thing play out, and from the motion you can now re-create a 3D model,
which accurately shows both objects in motion, despite both's event horizons.
When this data is merged with other types of detection and synchronized, you can then also
tell the size of the event horizon, and by overlaying the trajectories of the objects you can also
see motion through the lensing effects, that may occur just that bit longer than the sensitivity
of the gravimetrics have reached their limit and thus tell you the physical dimension or at least
get a close approximation of such, with greater detail than current gravimetrics allow.
This all then is achieved through Multi-Messenger Astronomy which combines or cooperates
in such a fashion that all possible data that can be collected also is collected, emphasis is,
and also is collimated into one single data source, which subsequently tells a whole
lot more than just a single data source about said phenomenon.
Once the full array of data collectors (telescopes) are in play you'd ahve more than enough
data to make very intricate conclusions on just about anything happening in the Universe,
after watching a few events, which then harden as predictions either get proven or disproven
upon repeated observation. That is explorative astrophysics at it's very finest.
I love how the audio of the merger sounds like a bubble popping. It seems intuitively appropriate.
I have a question. Why don't grav waves interfere with each other as they travel? How do we know that what we get here is a single ripple from a single event, and not actually the combination of an infinite number of grav wave events? Would 1 grav wave survive if another collision happened on the path between it and us? Wouldn't this kind of scenario mean you can't reverse engineer the size of the black holes of a single event? What am I missing?
They pass through each other just like light does. In fact, water waves also do that as long as they are small waves.
As soon as waves start to foam or crest, they can splash and lose energy instead of passing easily through each other. Gravity waves don't crest or splash I guess!
1:49 The link is *never* in the description.
Ed is the man.
Does black holes have north and south poles? Does angle between axis of rotation of colliding black holes make the difference? (should I be worry about it?)
Hello Dr. Copeland as you mention the Hubble tension have you read the paper "A Test of the Cosmological Principle with Quasars" (Nathan J. Secrest et al 2021 ApJL 908 L51)? The paper performs a experimental test of the Kinematic dipole assumption proposed in the 1980's and the large sample size of 1.36 million distant quasars has some very serious implications for our standard cosmological assumptions effectively falsifying the validity of the kinematic dipole assumption and thus in turn falsifying the cosmological principal by showing that the CMB dipole contains a significant nonzero cosmological component of some kind. The findings have a statistical significance of 4.9 sigma deviation from the predictions of a kinematic dipole or a 1 in 2 million chance of being a statistical fluke.
This might be enough to clean up the Hubble tension due to the large systematic bias that any model with the cosmological principal assumption built in. Never forget about systematic bias!
Not related to the video, I love the new channel icon
I'm waiting patiently for the video about Bradyons.
The description of receiving a "chirp" and then correlating/comparing it to templates sounds a lot like how modern radars work, so the principle makes sense. But in this case, the signal levels involved are staggeringly minute!
Say we know exactly where to look in the sky at the same exact time we detect a meger, can we visibly see the evidence of a said merger (via supernova type explosion or astrophysical jet type deal) at the same time we detect them? Since the visible light and gravitational waves travel at the same speed.
Mind blowing, seriously mind blowing.