It's interesting that this has made it to HN! My research is on the dynamics of few body systems so I know OJ 287 well! One of the projects I've been wanting to work on but haven't gotten around to is about this system. As the article mentions, OJ 287 is strange because it is a blazar (which is very rare, since the outflow has to be pointed directly at us) and is in a binary (which is also rare), yet it also happens to be the largest black hole known in the universe! So one could say that there's a low prior for such a system to exist.
The reason that OJ 287 has to be so massive in this model is because the orbit of the secondary black hole precesses so rapidly. For GR to give you that precession rate, you need a very, very massive black hole.
An alternative model I would like to explore is a three-body model for OJ 287. If this black hole binary is orbited by a tertiary black hole, the tertiary can also induce precession in the inner binary, so OJ 287 would not need to be so massive, which would make the triple model more plausible. It's unclear yet whether the triple dynamics can reproduce the observed lightcurve of OJ 287, though, so this is just an idea that's been on my to-do list for a year now. Let me know if you have any questions!
Its good to see more Astrophysicists using HN. I am very much interested in studying the workings of the cosmos, but I am not a professional degree holder in space science. I do freelance software development, but want to catch up with astrophysics too. Is it possible?
> While the ellipse that Mercury’s orbit makes around the Sun precesses at a rate of 43"-per-century due to relativistic effects (where 1° is 3600"), this smaller black hole should precess at 39°-per-orbit, and should inspiral in to the larger one in a timeframe of just a few thousand years!
In case anyone's curious: The double-quote is an arc-second. When measuring angles, a single quote is an arc-minute, which is 1/60th of a degree. An arc-second is, of course, 1/60th of an arc-minute. Rifle accuracy is measured in minutes of arc, with 1' being about an inch diameter circle at 100 meters. Proxima Centauri has a parallax of about 0.8".
To give you an idea of how far away Proxima Centauri is, we can scale everything down. A light-year is about 63,240 AU. A mile is 63,360 inches. So if Terra was an inch from Sol, Proxima Centauri would be about 4 miles away. The parallax from Proxima Centauri is the same as if you looked at an object 4 miles away, then moved your head 2 inches laterally. That's 0.8 arc-seconds. That's the second-closest star to us.
(Incidentally that's what defines a "parsec" -- a unit of distance of about 3 light years. If you see a parallax of one arcsecond ("par-sec"), from opposite sides of the earth's orbit around the sun (2 AU apart), that something is 1 parsec away. If it's 10 parsecs away, the parallax will be 0.1 arcsec -- the more distant the object, the less it appears to shift. This works to about 0.001 arcsec of precision (distance limit of ~1,000 parsecs), and soon down to 20 microarcseconds (~50,000 parsecs).
I've thought about scaled-down solar system models before but never encountered the coincidence between AUs in a lightyear and inches in a mile. That's effin' beautiful! Thank you!
On a related note, I never understood how a black hole (or frozen stars like the Russians call them) could potentially orbit or be swallowed by another black hole. If they "infinitely" deform space-time, shouldn't they be unable to move at all? If time stands still past the event horizon as they say and they also rip the space-time fabric so much, they shouldn't be able to "get out of the hole". This is just too mind-bogging for me I guess.
I believe black holes can be treated as normal astronomical objects outside their event horizon. The weird singularity behavior only applies within the event horizons.
i believe stephen hawking stated that matter does/or could escape black holes, but this subject matter is beyond my expertise so i suggest you ask him.
with that being said, it would seem to me that yes, black holes can move, our milky way is not stationary, and black holes have been known to have very fast rotation speeds.
The animation blew my mind. Especially S0-16. What the heck was that thing's velocity at perihelion? A whole star moving that much, that fast, accelerating like that in only 16 years. An entire star, tossed about in space like a ragdoll.
"Given a recent estimate of 4.3 million solar masses for the
mass of Sagittarius A* and S2's close approach, this makes
S2 the fastest known ballistic orbit, reaching speeds
exceeding 5000 km/s (11,000,000 mph) or 1.67~% of the speed
of light and acceleration of about 1.5 m/s2 or almost
one-sixth of Earth's surface gravity.[7]"
That blazar picture - it would be nice if articles would always credit it as 'artist's conception'. It almost looked like a feasible real light image with the pixellation, so I was rather intrigued.
Here is the one thing that really keeps me awake at night: what if our science was the equivalent of a bunch of ants in a typical ant hill in anyone of our backyards, defining a mechanism or "method" through which they have explained for themselves the nature of the solar system?
Science answers questions with evidence. None of this armchair conjecturing about what ifs. You don't increase smartphone screen resolutions and put rovers on mars with what ifs. Tangible benefits are the fruit of science. Objective results. None of this subjective shit you get from quackery. There's no room for interpretation when a SpaceX Dragon docks at the space station, that happened. Unless you are into solipsism.
There is nothing to shake off when it comes to science. If good science led us to wrong answers it is because of insufficient data, bad process, and human error. Science is the best tool we have ever created. Just look at your smartphone. The transistors in that thing are not individually visible with the human eye but you can post your selfies to snapchat just fine right? Right. Those transistors are measured in nanometers.
Well, for one thing we haven't found any other anthills and that's very weird. Other than that, just
Stay Calm
and
Keep Doing Science
until you've scienced everything. The analogy with ants is weird, in that ants don't seem to be sentient and don't appear to have ant scientists that are trying to understand the mysteries of the universe. That makes it a bit hard to answer you on the level of the analogy, as such an answer would need to start with "assuming ants were sentient and had physicists, ...", from which point on the rest would be pure anthropocentric conjecture. We humans are a bit unique in that there are individuals who go "well I'm bored, guess I'll go observe the sun, moon and other bright discs in the night sky for decades and record their movements as precisely as I can, so that some other person, most probably of a race I've never seen from a place far beyond any horizon I've viewed, can read them centuries later and use them to come up with a heliocentric model of the solar system and from there on other mad toffs with nothing better to do could come up with the theory of gravity or something".
There is no reason to believe we will never ever find out some fundamental properties of the world, given enough time. If something exists, it can be interacted with and if it can be interacted with, it can be studied. If we can't interact with it ourselves, we'll make machines to interact with it. If we cannot make machines to interact with it, we'll study the results of other things interacting with it that we can observe. If it cannot be interacted with in any way via any method, its existence is largely a philosophical question.
It can be argued that we don't (and won't) have the absolute most simple, exact and perfect formulations for the rules of nature, but arguing whether those rules have a one true form and if there aren't equivalent ways to state them is again a largely philosophical question.
if the universe keeps expanding, eventually it will expand at the speed of light and everything that is not gravitationally locked with us (wich only includes the milky way and about 5 or so other galaixies) will be moving faster than the speed of light and will be impossible to observe in any way.
in a sense, it means leo is actually wrong. if an intelligent race comes into being after said event, it could be true that no amount of science will ever be able to show that the rest of the universe existed. that also means some other phenomenon may have occurred that will make us as just as useless at understanding what happened as ants are at knowing/exploring the stars.
that is, if certain theories about the expansion of the galaxy is true.
Newton's law of gravity? Worked great for, what, 300+ years? Still, for a wide range of situations, it's darned accurate. Is it 'correct'? Nope: Einstein's law of gravity is more accurate, especially in what in our solar system neighborhood would have to be regarded as extreme situations.
Are we sure that Einstein's law of gravity is the really 'correct' one or the 'last' one we will discover? Nope. Indeed, that doubt is part of why the article got so excited about using one black hole orbiting another one to "test" Einstein's law of gravity. We keep testing that law because we will learn something, either (1) something doesn't fit and we have to ditch the law or (2) the law fits and we gain more 'confidence' in the law.
You can look at it this way: The stuff we 'accept' now is what we have dreamed up and that has passed some apparently 'significant' (don't mean statistics here) tests and so far never really failed a test. Net, stuff 'accepted' at present is what appears to work so far.
But, in physics and cosmology, we have some issues that, at least intuitively, appear to be potential biggies: (1) What happened before the big bang? Can we get some clues from the data we have on what might have happened before the big bang -- some physicists have tried to look. (2) What's with this stuff about dark energy and dark matter? (3) Why does it appear that there is much more matter than anti-matter? (4) What's with neutrinos and how they 'change'? (5) What can we dig out of 'spooky action at a distance', that is, Einstein–Podolsky–Rosen (EPR) paradox?
So, maybe more progress understanding one of these biggies will cause us to ditch some of our currently 'accepted' results, look for, and maybe find some new results.
Could everything we have seen so far be just some light show put on just for our amusement? We can't say. So far, it appears that somehow mathematics works shockingly well; why? We don't know.
That there is a law of gravity that works as well as even Newton's might be seen as surprising. That is, why doesn't
the 'law of gravity' change each 10 minutes? Well, some things do change 'randomly', and for them the only laws we have are probabilistic. Newton's law is not probabilistic because so far it appears to work the same yesterday, today, and tomorrow, that is, doesn't change. Or our science is what we have found that in some important sense doesn't change, e.g., we can 'reproduce' results. Why are such results possible? Not at all clear.
Even if what we are seeing is just some light show for our amusement, still we get some utility, e.g., via applications to engineering, etc. So, the Internet works because Maxwell's equations of electro-magnetism continue to work as they have for 100+ years now.
> And I can't shake it off.
Relax and enjoy the light show or whatever the heck it is. There's a lot to be amazed about, curious about, etc. And we really do make progress, astounding progress. E.g., we've made a lot of progress since I studied physics i college. The math I studied has been more stable!
Wow. In my memory, it was the pressure from the hot gases that kept a star from collapsing on itself. I did not know it was light pressure! Is this a typo in the article, or is it really light pressure holding up stars?
what superenergetic catastrophe happens when those two black holes collapse onto each other?
Is this black hole pair likely to be two galactic cores that collided, and captured each other due to some sort of inelastic interaction (maybe ejecting stars out?) and their surrounding galactic matter got eaten up due to basically the three-body problem?
There did seem to be some random emphasis going on in that article (not just with italics but with bold text too). It was a little distracting in places (maybe just because I'm dyslexic?) but the article was fascinating enough to keep me reading.
I was a little disappointed that the article ended with speculation though. Given the title, I was expecting something more concrete. But I guess I should be grateful that the author didn't feel the need to sensationalise the truth for the sake of narrative (like so many reporters do these days).
Same here, except that in the end I didn't like the article. Medium is very fit for startup chatter and discussions on the relative merits of ios 8 and android 2.2. But writing about science in Medium, using this style and narrative? Not for me.
Well, I'm having a nice big existentialist crisis right now having being reminded of our place in the universe. I'm going to go pour myself a whiskey and hug my kids. G'night everybody.
Maybe a quote by David Deutsch will ease the pain:
"Some people get depressed when they find out how huge the universe is. They feel tiny and insignificant and think that nothing matters in this world.
That makes no more sense than getting depressed when you find out that cows are bigger than you. What is the big deal about bigness? A cow is much bigger than you, but it is a ridiculous animal and you are a valuable person. You know it’s a cow. It doesn’t know anything. it just stands there eating grass (grass!) and mooing. And if it were bigger, that would only make it more ridiculous."
[+] [-] antognini|11 years ago|reply
The reason that OJ 287 has to be so massive in this model is because the orbit of the secondary black hole precesses so rapidly. For GR to give you that precession rate, you need a very, very massive black hole.
An alternative model I would like to explore is a three-body model for OJ 287. If this black hole binary is orbited by a tertiary black hole, the tertiary can also induce precession in the inner binary, so OJ 287 would not need to be so massive, which would make the triple model more plausible. It's unclear yet whether the triple dynamics can reproduce the observed lightcurve of OJ 287, though, so this is just an idea that's been on my to-do list for a year now. Let me know if you have any questions!
[+] [-] z3phyr|11 years ago|reply
[+] [-] lovemenot|11 years ago|reply
I have no other knowledge, but just from the information in your comment, can we test the low prior assumption?
Would this bh still have been identifiable as the most massive known, if it did not have both of the following characteristics?
- blazar, pointed directly at us (makes it noticeable)
- binary, (makes it measurable at such a massive scale)
[+] [-] ggreer|11 years ago|reply
In case anyone's curious: The double-quote is an arc-second. When measuring angles, a single quote is an arc-minute, which is 1/60th of a degree. An arc-second is, of course, 1/60th of an arc-minute. Rifle accuracy is measured in minutes of arc, with 1' being about an inch diameter circle at 100 meters. Proxima Centauri has a parallax of about 0.8".
To give you an idea of how far away Proxima Centauri is, we can scale everything down. A light-year is about 63,240 AU. A mile is 63,360 inches. So if Terra was an inch from Sol, Proxima Centauri would be about 4 miles away. The parallax from Proxima Centauri is the same as if you looked at an object 4 miles away, then moved your head 2 inches laterally. That's 0.8 arc-seconds. That's the second-closest star to us.
[+] [-] throwaway_yy2Di|11 years ago|reply
https://en.wikipedia.org/wiki/Parsec
https://en.wikipedia.org/wiki/Hipparcos
https://en.wikipedia.org/wiki/Gaia_%28spacecraft%29
This is the lowest rung of the "cosmic distance ladder":
https://en.wikipedia.org/wiki/Cosmic_distance_ladder
https://terrytao.wordpress.com/2010/10/10/the-cosmic-distanc...
[+] [-] fernly|11 years ago|reply
[+] [-] alixaxel|11 years ago|reply
On a related note, I never understood how a black hole (or frozen stars like the Russians call them) could potentially orbit or be swallowed by another black hole. If they "infinitely" deform space-time, shouldn't they be unable to move at all? If time stands still past the event horizon as they say and they also rip the space-time fabric so much, they shouldn't be able to "get out of the hole". This is just too mind-bogging for me I guess.
[+] [-] wyager|11 years ago|reply
[+] [-] deepsun|11 years ago|reply
But I greet the new legend about Russians that just born here!
[+] [-] DanielRibeiro|11 years ago|reply
TL;DR: blackhole mergers are really rare, because one often kicks the other out.
[+] [-] Sniffnoy|11 years ago|reply
[+] [-] oakwhiz|11 years ago|reply
[+] [-] autokad|11 years ago|reply
with that being said, it would seem to me that yes, black holes can move, our milky way is not stationary, and black holes have been known to have very fast rotation speeds.
[+] [-] Pxtl|11 years ago|reply
[+] [-] throwaway_yy2Di|11 years ago|reply
Edit: wait that's not it, that's S0-2, but you're talking about S14/S0-16:
https://en.wikipedia.org/wiki/Sagittarius_A*#Central_black_h...
From those parameters, its perihelion speed would be about 8,200 km/s (2.7% c), using the classical approximation.
https://en.wikipedia.org/wiki/Perihelion#Mathematical_formul...
[+] [-] thatthatis|11 years ago|reply
Also, helps to remind me of how cosmically tiny the problems of building my SaaS product really are.
[+] [-] sharkweek|11 years ago|reply
http://www.nasa.gov/images/content/136063main_bm4_high.jpg
Then to get an astronomically bigger picture of just how small we all are, I start getting dizzy at even the thought.
[+] [-] m_mueller|11 years ago|reply
[+] [-] hyperliner|11 years ago|reply
That's the one thing. And I can't shake it off.
[+] [-] leorocky|11 years ago|reply
There is nothing to shake off when it comes to science. If good science led us to wrong answers it is because of insufficient data, bad process, and human error. Science is the best tool we have ever created. Just look at your smartphone. The transistors in that thing are not individually visible with the human eye but you can post your selfies to snapchat just fine right? Right. Those transistors are measured in nanometers.
[+] [-] anon4|11 years ago|reply
There is no reason to believe we will never ever find out some fundamental properties of the world, given enough time. If something exists, it can be interacted with and if it can be interacted with, it can be studied. If we can't interact with it ourselves, we'll make machines to interact with it. If we cannot make machines to interact with it, we'll study the results of other things interacting with it that we can observe. If it cannot be interacted with in any way via any method, its existence is largely a philosophical question.
It can be argued that we don't (and won't) have the absolute most simple, exact and perfect formulations for the rules of nature, but arguing whether those rules have a one true form and if there aren't equivalent ways to state them is again a largely philosophical question.
[+] [-] undershirt|11 years ago|reply
[+] [-] autokad|11 years ago|reply
if the universe keeps expanding, eventually it will expand at the speed of light and everything that is not gravitationally locked with us (wich only includes the milky way and about 5 or so other galaixies) will be moving faster than the speed of light and will be impossible to observe in any way.
in a sense, it means leo is actually wrong. if an intelligent race comes into being after said event, it could be true that no amount of science will ever be able to show that the rest of the universe existed. that also means some other phenomenon may have occurred that will make us as just as useless at understanding what happened as ants are at knowing/exploring the stars.
that is, if certain theories about the expansion of the galaxy is true.
[+] [-] unknown|11 years ago|reply
[deleted]
[+] [-] Detrus|11 years ago|reply
Of course, the ones in your backyard typically don't do that. Those are like boring human villages.
[+] [-] graycat|11 years ago|reply
Are we sure that Einstein's law of gravity is the really 'correct' one or the 'last' one we will discover? Nope. Indeed, that doubt is part of why the article got so excited about using one black hole orbiting another one to "test" Einstein's law of gravity. We keep testing that law because we will learn something, either (1) something doesn't fit and we have to ditch the law or (2) the law fits and we gain more 'confidence' in the law.
You can look at it this way: The stuff we 'accept' now is what we have dreamed up and that has passed some apparently 'significant' (don't mean statistics here) tests and so far never really failed a test. Net, stuff 'accepted' at present is what appears to work so far.
But, in physics and cosmology, we have some issues that, at least intuitively, appear to be potential biggies: (1) What happened before the big bang? Can we get some clues from the data we have on what might have happened before the big bang -- some physicists have tried to look. (2) What's with this stuff about dark energy and dark matter? (3) Why does it appear that there is much more matter than anti-matter? (4) What's with neutrinos and how they 'change'? (5) What can we dig out of 'spooky action at a distance', that is, Einstein–Podolsky–Rosen (EPR) paradox?
So, maybe more progress understanding one of these biggies will cause us to ditch some of our currently 'accepted' results, look for, and maybe find some new results.
Could everything we have seen so far be just some light show put on just for our amusement? We can't say. So far, it appears that somehow mathematics works shockingly well; why? We don't know.
That there is a law of gravity that works as well as even Newton's might be seen as surprising. That is, why doesn't the 'law of gravity' change each 10 minutes? Well, some things do change 'randomly', and for them the only laws we have are probabilistic. Newton's law is not probabilistic because so far it appears to work the same yesterday, today, and tomorrow, that is, doesn't change. Or our science is what we have found that in some important sense doesn't change, e.g., we can 'reproduce' results. Why are such results possible? Not at all clear.
Even if what we are seeing is just some light show for our amusement, still we get some utility, e.g., via applications to engineering, etc. So, the Internet works because Maxwell's equations of electro-magnetism continue to work as they have for 100+ years now.
> And I can't shake it off.
Relax and enjoy the light show or whatever the heck it is. There's a lot to be amazed about, curious about, etc. And we really do make progress, astounding progress. E.g., we've made a lot of progress since I studied physics i college. The math I studied has been more stable!
[+] [-] mathattack|11 years ago|reply
[+] [-] e40|11 years ago|reply
So we are just incredible lucky to be here at this moment to have observed it? Fascinating.
[+] [-] kghose|11 years ago|reply
[+] [-] avar|11 years ago|reply
[+] [-] dnautics|11 years ago|reply
Is this black hole pair likely to be two galactic cores that collided, and captured each other due to some sort of inelastic interaction (maybe ejecting stars out?) and their surrounding galactic matter got eaten up due to basically the three-body problem?
[+] [-] imaginenore|11 years ago|reply
[+] [-] kabdib|11 years ago|reply
[+] [-] laumars|11 years ago|reply
I was a little disappointed that the article ended with speculation though. Given the title, I was expecting something more concrete. But I guess I should be grateful that the author didn't feel the need to sensationalise the truth for the sake of narrative (like so many reporters do these days).
[+] [-] gbog|11 years ago|reply
[+] [-] unknown|11 years ago|reply
[deleted]
[+] [-] Pxtl|11 years ago|reply
[+] [-] ckuehne|11 years ago|reply
"Some people get depressed when they find out how huge the universe is. They feel tiny and insignificant and think that nothing matters in this world.
That makes no more sense than getting depressed when you find out that cows are bigger than you. What is the big deal about bigness? A cow is much bigger than you, but it is a ridiculous animal and you are a valuable person. You know it’s a cow. It doesn’t know anything. it just stands there eating grass (grass!) and mooing. And if it were bigger, that would only make it more ridiculous."