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."

Comments

Red Dwarf question

[Vintermann]

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?

Re:Interstellar pic ?

[pablo_max]

ah..yes, it does apparently.
http://thefilmstage.com/news/h...

It's already been proven.

[Le Marteau]

> 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.

Re:It's already been proven.

[Le Marteau]

Correction: It's called "Sagittarius A*" And NASA does not qualify it using terms such as "might be a black hole" or "theorised to be a black hole." They simply call it a "supermassive black hole"

http://www.nasa.gov/mission_pa...

How can it prove it when

[Prune]

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.

Re:How can it prove it when

[amaurea]

In general your model is broken because you're not considering the metric. The most important effect you are neglecting in this case is the time-time component of the metric, which indicates how quickly stationary local clocks tick compared to coordinate time (there is also the radius-radius component which tells you that the event horizon is much further away than you would naively think, but we'll ignore that here). It looks like this for the metric outside a nonrotating, uncharged, massive body: 1-R/r, where R is the Schwartzchild radius of that source, and r is a radial coordinate. At large distances this factor approaches 1, so coordinate time moves at the same speed as the time of a far-away observer, such as us here on earth. But as r approaches R, the factor goes to 0. So time close to the horizon moves ever more slowly as one gets closer to it, according to our far-away reference frame. That is why crossing the horizon takes an infinite amount of (our) time.

However, the frequency and intensity of light is multiplied by the same factor, and very quickly becomes almost zero. So you would not see the object hanging there forever. You would see it quickly fade to blackness, leaving an incredibly faint and ever fainter afterimage in far radio wavelengths.

That's nitpicking

[amaurea]

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".

Business Insider?

[jbmartin6]

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.

I work on this project...

[NixieBunny]

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.

Re:I thought that black holes don't exist?!??

[amaurea]

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.