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How Astronomers Will Take the "Image of the Century": a Black Hole
An anonymous reader writes with news that scientists may be close to getting the first image of a black hole. "Researchers studying the universe are ramping up to take the image of the century — the first ever image of a supermassive black hole. While the evidence for the existence of black holes is compelling, Scientists will continue to argue the contrary until physical, observational evidence is provided. Now, a dedicated team of astrophysicists armed with a global fleet of powerful telescopes is out to change that. If they succeed, they will snap the first ever picture of the monstrously massive black hole thought to live at the center of our home galaxy, the Milky Way. This ambitious project, called the Event Horizon Telescope (EHT), is incredibly tricky, but recent advances in their research are encouraging the team to push forward, now. The reason EHT needs to be so complex is because black holes, by nature, do not emit light and are, therefore, invisible. In fact, black holes survive by gobbling up light and any other matter — nearby dust, gas, and stars — that fall into their powerful clutches. The EHT team is going to zoom in on a miniscule spot on the sky toward the center of the Milky Way where they believe to be the event horizon of a supermassive black hole weighing in at 4 million times more massive than our sun. We can still see the material, however, right before it falls into eternal darkness. The EHT team is going to try and glimpse this ring of radiation that outlines the event horizon. Experts call this outline the "shadow" of a black hole, and it's this shadow that the EHT team is ultimately after to prove the existence of black holes."
Well, the thing about a Black Hole, its main distinguishing feature, is it's black. And the thing about space, your basic space colour is black. So how are you supposed to see them?
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I can not help but wonder at the question: "Will the produced image in any way resemble the black hole depiction in the 'Interstellar' movie ?"
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We know quasars exist and involve radiation blasted out from the fucktons of matter pouring into early-universe supermassive blackholes.
What has yet to happen is someone has yet to image the black part of the black hole. The region that's quite literally so dark that light just falls into it. (depending on how thin the accretion disk is, it might not actually be black -- but it's going to be a hell of a lot less energetic than the regions near the disc/equator!). That's the image of the century: not the radiation blasted out from relativistic shockwaves of the unholy weirdness near a black hole, but the relative blackness of the event horizon itself against the backdrop of aforementioned unholy weirdness.
No quasars around here, the universe is over that by now. We have no tech with resolution sufficient to image a stellar mass black hole in my lifetime. But the big-ass one a mere 30000 light years away? Being so (relatively speaking) close makes up for all the gas and dust that's in the way. That one's observable. And yes, I've been wanting to see that image for about 30 years, and it can't come too soon.
> the EHT team is ultimately after to prove the existence of black holes."
It's already been proven. There is a black hole at the center of the Milky Way galaxy, and it's been named "Sagitarius A"
Using infrared telesopes, you can "see" stars orbiting the black hole at the center of the galaxy. Orbits of about 28 stars have been observed and using math, the mass of the stars and the required mass of the black hole has been calculated. Only a black hole can account for the kinds of orbits you see those stars doing.
It is a sight to behold and at first I could not believe it. Watching the stars at the frickin center of the galaxy orbit a black hole is a stunning sight once you truly grok what you are seeing.
https://www.youtube.com/watch?...
Realize that this video is not an artist's intepretation, but is actual imagery of stars orbiting something of immense mass, something which can only be a black hole.
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Except....that a black home has a bottom. There's nothing infinite about them, except in some formulas (i.e. the _mathematical_ singularity at the center). If the black hole is big enough (around 150 billion solar masses), you could even stand more or less comfortably on its surface, normal earth-like gravity, provided the radiation doesn't kill you.
The surface of the collapsing star takes an infinite time to cross the event horizon form the point of view of an outside observer? No star which has collapsed has yet turned into a black hole, and no one will at a finite age of the outside universe. The only way to prove the existence of a black hole is to fall through an event horizon. Of course, then you only prove it for yourself, and cannot tell anyone else.
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Earth is orbiting the BH in the galactic plane, so wouldn't the ring of fire be seen edge on from our perspective?
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The surface will get very close to the apparent horizon very quickly though, and after that it will be so redshifted that it looks just like one of the idealized black hole solutions, and will be indistinguishable from one to any observer. It will be just as black, just as compact and just attractive, and still deserves to be called a black hole. When people say "black hole" they don't necessarily mean "Schwartzchild black hole" or "Kerr black hole".
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What use is a link to a science article on Business Insider? Here is the EHT project home page It seems the goals of the project are a lot more interesting than simply proving black holes exist.
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If you have any actual questions about how it's done. I might be able to shed some light on what this thing is. It involves masers and 4K fridges and some rather high IF frequencies.
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It would be nice if science reported were color coded or something. Green for robust, independently verified and generally accepted stuff (general relativity, evolution, etc.), yellow for new stuff that's not yet independently verified but in line with well-tested models, and red for stuff that's exciting but very uncertain and/or likely to be wrong (faster-than-light neutrinos, string theory, dark matter annihilation observations in galaxies, etc). The sort of stuff you read about in the news is usually red or yellow, but is presented as if it were green. The article you quote falls squarely into the red category.
What about this story makes you think Hawking radiation doesn't exist? We can't be completely sure it exists because we don't have any observations of it, but there are compelling theoretical reasons to believe it should exist. But for non-tiny black holes, it is extremely faint, so faint that we have no hope of observing it. For example, the supermassive black hole in the center of the milky way would be expected to radiate 3.6e-48 W. That's 1 with 50 zeros behind it times weaker than a light bulb!
How can anyone argue that black holes don't exist? I mean we've tracked stars at the center of our galaxy orbiting something at extreme speeds. We've never seen electrons, but we've all but confirmed their existence by how they interact with our environment.
That's a fascinating article, but you won't find many astrophysicists who would bet on it being correct (this probably includes the authors). Traversable wormholes are unstable without large amounts of negative mass, and we have no reason to believe that such exotic matter even exists. And if one is willing to assume that these wormholes have been there since the beginning of the universe in order to explain the presence of compact massive bodies in the center of every galaxy, then you might as well assume that black holes have been there since the beginning of the universe - that requires much less speculative new physics while solving the same problems. And those problems aren't that convincing in the first place - properly including baryons in cosmological simulations may well turn out to produce the right amount of large black holes when we get good enough computers to run them.
This is a typical case of somebody doing a fun "what if" or "devil's advocate" calculation, and the media turning it into something much more definite than it is.
I work on the engineering side, rather than the project management side. The two EHT telescopes that I work on are in Arizona, although I build some of the hardware that's being taken to the South Pole Telescope. It's getting improved to be a part of the EHT. One of the Arizona telescopes is a prototpye ALMA antenna that we just moved here from New Mexico last year, and got working a month ago.
Observations are typically done in March/April. This gives good weather at the many sites involved. The typical run is a week, and they try to get several 10-minute recordings during that time period. The data is recorded at 1 Gbyte/sec onto banks of hard drives, then shipped by FedEx to MIT for correlation. (I don't know if a FedEx truck makes it to the South Pole every day.)
The frequency used for most observations in in the 1.3mm band. The baselines are intercontinental (Arizona, Hawaii, Chile, hopefully Antarctica), up to 5000 miles. The goal is to actually get fringes between all stations, although that's not always possible due to weather and/or equipment acting up.
The determined Real Programmer can write Fortran programs in any language.