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The Largest Black Hole in the Known Universe

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Re: The Largest Black Hole in the Known Universe

#51
post #39

It not the complete list: http://en.wikipedia.org/wiki/List_of_most_massive_black_hole... 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-t…

I'm Russian, and I've never heard "frozen star". In Russian, black hole is literally "black hole". But I greet the new legend about Russians that just born here!

Not just born here. I've heard it before, at least 20 years ago. The version of the legend I heard is that "black hole" in Russian is (or suggests) an obscenity, so for a long time Russian physicists didn't want to use that term.

The term "frozen star" has certainly been used for black holes. If you Google both terms you'll find an article from 1971 called "Introducing the black hole", by Ruffini and Wheeler, which mentions that term. (It doesn't say anything about Russian obscenities, though.)

Re: The Largest Black Hole in the Known Universe

#52
post #45

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…

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?

It is possible! But how you go about doing it would depend on your goals, how much time you would have for it, and how much physics and math you know.

The thing about astronomy is that it changes quickly, but not that quickly. The timescale for major changes in our knowledge of astronomy is perhaps ~10 years or so (that's usually how long it takes a big problem to be solved), so it's not as though it's something you need to keep on top of every day or every week. (Unless you're a professional astronomer and want to be aware of all the new papers coming out.) As a consequence of this, textbooks are a good place to start for background. There are tons, but Carroll & Ostlie is a good general introduction to all aspects of modern astrophysics. Each chapter also has general and technical references so you know where to go to learn more about any subjects that you find interesting.

For discussions of current problems in astronomy, the journal Annual Reviews in Astronomy & Astrophysics is a good place to start. Current articles are paywalled, but most of them appear on arxiv.org, so you can search for them there. They contain summaries of all the recent research on a particular problem. If you're interested in learned more about that particular problem, they're a good place to start because they'll point you to all the important papers on the subject.

Another good resource is ADS. You can search for papers here: http://adsabs.harvard.edu/default_service.html You can search for specific papers, or just search for papers with a particular keyword in the abstract or title. There's a handy feature that lets you sort by citations so that you can easily find the most influential papers.

Finally, you can find the newest papers here: http://arxiv.org/list/astro-ph/new About ~50 new papers appear here every weekday. It's a lot to keep up with even if you're a professional, but it can be useful to skim the titles every now and again and see what looks interesting. The introduction to astronomy papers usually acts as a sort of mini-review article. It'll review the problem that the paper is examining and will reference other papers that have looked at this problem. So from reading introductions you can get some background on the problem and the ways that astronomers have been trying to solve it -- and it's a lot shorter than a full review article!

Some of the problems may seem somewhat opaque if you don't have the necessary physics background, but not all of them are, so don't get discouraged! Or if that inspires you to learn more physics, so much the better!

Re: The Largest Black Hole in the Known Universe

#53
post #46

Earlier quoted context omitted.

A cow is still well within the realm of dimensions that a human mind can comprehend. You won't feel insignificant when looking at a cow because while bigger, it's not that much bigger. Apart from poisoning you when you eat it, or kicking you by mistake, it has relatively little influence or impact on you, your life, your fate, or indeed, the fate of the human race. Now, if you had a cow the size of the earth, that ju…

For me, it is the opposite. If the world was small, I would be sad to be a part of a small un-awesome world. Looking at how big the world is makes me happy and excited. The difference I guess comes from whether you see yourself as a part of the universe or as an observer separate from the rest of the world.

I didn't say it made me sad. I just said it made me (and you) fairly insignificant in the greater scheme of things.

Insignificance is awesome. Significance seems highly overrated, more to do with assuaging one's ego than with enjoying life.

Re: The Largest Black Hole in the Known Universe

#54
post #15

> 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…

(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).

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...

Re: The Largest Black Hole in the Known Universe

#55
post #15

> 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…

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!

Re: The Largest Black Hole in the Known Universe

#56
post #53

Earlier quoted context omitted.

For me, it is the opposite. If the world was small, I would be sad to be a part of a small un-awesome world. Looking at how big the world is makes me happy and excited. The difference I guess comes from whether you see yourself as a part of the universe or as an observer separate from the rest of the world.

I didn't say it made me sad. I just said it made me (and you) fairly insignificant in the greater scheme of things. Insignificance is awesome. Significance seems highly overrated, more to do with assuaging one's ego than with enjoying life.

The key is to have no ego. That makes any question of significance insignificant :)

Re: The Largest Black Hole in the Known Universe

#57
post #51
post #39

Earlier quoted context omitted.

I'm Russian, and I've never heard "frozen star". In Russian, black hole is literally "black hole". But I greet the new legend about Russians that just born here!

Not just born here . I've heard it before, at least 20 years ago. The version of the legend I heard is that "black hole" in Russian is (or suggests) an obscenity, so for a long time Russian physicists didn't want to use that term. The term "frozen star" has certainly been used for black holes. If you Google both terms you'll find an article from 1971 called "Introducing the black hole", by Ruffini and Wheeler, which…

"Black hole" is not really an obscenity in Russian as much as it isn't in English.

But the paper you quoted does seem to explain the logic for this term's existence:

"The resulting system has been variously termed “continuing collapse,” a “frozen star,” and a “black hole.” Each name emphasizes a different aspect of the collapsing system. The collapse is continuing because even after an infinite time, as measured by a distant observer, the collapse is still not complete. Rather, the departure from a static configuration of Schwarzschild radius r=2m as seen by a distant observer diminishes exponentially in time, with a characteristic time of the order of 2m, or about 10 microseconds for an object of one solar mass. The box explains the purely geometrical system of units employed in general relativity. In this sense, the system is a “frozen star.”

In another sense, the system is not frozen at all. On the contrary, the dimensions shrink to indefinitely small values in a finite and very short proper time for an observer moving with the collapsing matter (see figure 3). Moreover, a spherical system appears black from outside; no light can escape. Light shot at it falls in. A particle shot at it falls in.

A “meter stick” would be let down in vain to measure the dimensions of the object. The stick is pulled to pieces by tidal forces, and the broken-off pieces fall in without a trace. In these senses, the system is a black hole"

So this seems to be an international term, and indeed both the Russian wikipedia http://ru.wikipedia.org/wiki/%D0%A7%D1%91%D1%80%D0%BD%D0%B0%... and English-language one mention it.

Couple of other hits in search do mention that the term was used in 1960s - which probably explains the reason why it does sound a bit strange :-)

Anyway, it was fun to do this little investigation, thanks!

Re: The Largest Black Hole in the Known Universe

#58

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…

>> So one could say that there's a low prior for such a system to exist.

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)

Re: The Largest Black Hole in the Known Universe

#59

Made me think if this: http://m.youtube.com/watch?v=JWVshkVF0SY&feature=kp Also, helps to remind me of how cosmically tiny the problems of building my SaaS product really are.

Even this picture makes me think the same thing:

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.

Re: The Largest Black Hole in the Known Universe

#60
post #14
post #5

Nice article, but overuse of italics made me cut and paste into Emacs to read it.

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.

What style and narrative would you prefer?

I think StartsWithABang is an excellent read: entertaining iand informative. One of the few blog-type-things I follow anymore.

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