Scientists gear up to take a picture of a black hole

On Wednesday, Jan. 18, astronomers, physicists and scientists from related fields will convene in Tucson, Ariz. from across the world to discuss an endeavor that only a few years ago would have been regarded as nothing less than outrageous. The conference is organized by Dimitrios Psaltis, an associate professor of astrophysics at the University of Arizona's Steward Observatory, and Daniel Marrone, an assistant professor of astronomy at Steward Observatory.

"Nobody has ever taken a picture of a black hole," Psaltis said. "We are going to do just that."

"Even five years ago, such a proposal would not have seemed credible," added Sheperd Doeleman, assistant director of the Haystack Observatory at Massachusetts Institute of Technology (MIT), who is the principal investigator of the Event Horizon Telescope, as the project is dubbed. "Now we have the technological means to take a stab at it."

First postulated by Albert Einstein's , the existence of black holes has since been supported by decades' worth of observations, measurements and experiments. But never has it been possible to directly observe and image one of these maelstroms whose sheer gravity exerts such cataclysmic power they twist and mangle the very fabric of .

"Black holes are the most you can find in the universe," Doeleman said.

The field of gravity around a black hole is so immense that it swallows everything in its reach; not even light can escape its grip. For that reason, black holes are just that –emitting no light whatsoever, their "nothingness" blends into the black void of the universe.

So how does one take a picture of something that by definition is impossible to see?

"As dust and gas swirls around the black hole before it is drawn inside, a kind of cosmic traffic jam ensues," Doeleman explained. "Swirling around the black hole like water circling the drain in a bathtub, the matter compresses and the resulting friction turns it into plasma heated to a billion degrees or more, causing it to 'glow' – and radiate energy that we can detect here on Earth."

By imaging the glow of matter swirling around the black hole before it goes over the edge of the point of no return and plunges into the abyss of space and time, scientists can only see the outline of the black hole, also called its shadow. Because the laws of physics either don't apply to or cannot describe what happens beyond that point of no return from which not even light can escape, that boundary is called the Event Horizon.

"So far, we have indirect evidence that there is a black hole at the center of the Milky Way," Psaltis said. "But once we see its shadow, there will be no doubt."

Even though the black hole suspected to sit at the center of our galaxy is a supermassive one at four million times the mass of the Sun, it is tiny to the eyes of astronomers. Smaller than Mercury's orbit around the Sun, yet almost 26,000 light years away, it appears about the same size as a grapefruit on the moon.

"To see something that small and that far away, you need a very big telescope, and the biggest telescope you can make on Earth is to turn the whole planet into a telescope," Marrone said.

To that end, the team is connecting up to 50 radio telescopes scattered around the globe, including the Submillimeter Telescope (SMT) on Mt. Graham in Arizona, telescopes on Mauna Kea in Hawaii and the Combined Array for Research in Millimeter-wave Astronomy (CARMA) in California. The global array will include several radio telescopes in Europe, a 10-meter dish at the South Pole and potentially a 15-meter antenna atop a 15,000-foot peak in Mexico.

"In essence, we are making a virtual telescope with a mirror that is as big as the Earth," Doeleman said. "Each radio telescope we use can be thought of as a small silvered portion of a large mirror. With enough such silvered spots, one can start to make an image."

"The Event Horizon Telescope is not a first-light project, where we flip a switch and go from no data to a lot of data," he added. "Every year, we increase its capabilities by adding more telescopes, gradually sharpening the image we see of the black hole."

One crucial and eagerly expected key element about to join Event Horizon's global network of radio telescopes is the Atacama Large Millimeter Array, or ALMA, in Chile.

Comprising 50 radio antennas itself, ALMA will function as the equivalent of a dish that is 90 meters in diameter, and become what Doeleman called "a real game changer." "When ALMA comes online, it will double our resolution."

"The EHT will bring us as close to the edge of a black hole as we will ever come," the participating scientists wrote in a project summary.

"We will be able to actually see what happens very close to the horizon of a black hole, which is the strongest gravitational field you can find in the universe," Psaltis said. "No one has ever tested Einstein's Theory of General Relativity at such strong fields."

General Relativity predicts that the bright outline defining the black hole's shadow must be a perfect circle. According to Psaltis, whose research group specializes in Einstein's Theory of General Relativity, this provides an important test.

"If we find the black hole's shadow to be oblate instead of circular, it means Einstein's Theory of General Relativity must be flawed," he said. "But even if we find no deviation from , all these processes will help us understand the fundamental aspects of the theory much better."

Black holes remain among the least understood phenomena in the universe. Ranging in mass from a few times the mass of the Sun to billions, they appear to coalesce like drops of oil in water. Most if not all galaxies are now believed to harbor a supermassive black hole at their center, and smaller ones are scattered throughout. Our Milky Way is known to be home to about 25 smallish ranging from 5 to 10 times the Sun's mass.

"What is great about the one in the center of the Milky Way is that is big enough and close enough," Marrone said. "There are bigger ones in other galaxies, and there are closer ones, but they're smaller. Ours is just the right combination of size and distance."

The reason astronomers rely on radio waves rather than visible or infrared light to spy on the black hole is two-fold: For one, observing the center of the Milky Way from the Earth requires peering right through the plane of the galaxy. Radio waves are able to penetrate thousands of light-years worth of stars, gas and dust obstructing the view. Secondly, combining optical telescopes into a virtual super-telescope would not be feasible, according to the researchers.

Only very recent technological advances have made it possible to not only record radio waves at just the right wavelengths where they don't interfere with water vapor in the atmosphere but also to ensure the ultra-precise timing necessary to combine observations from multiple telescopes thousands of miles apart into one exposure.

Each telescope will record its data onto hard drives, which will be collected and physically shipped to a central data processing center at MIT's Haystack Observatory.

Bringing together radio telescopes around the globe requires an equally global team effort.

"This is not only the usual international conference where people come from all over the world because they are interested in sharing their research," Psaltis said. "For the Event Horizon Telescope, we need the entire world to come together to build this instrument because it is as big as the planet. People are coming from all over the world because they have to work on it."

Explore further

Astronomers Get Closest Look Yet At Milky Way's Mysterious Core

Citation: Scientists gear up to take a picture of a black hole (2012, January 14) retrieved 15 September 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Jan 14, 2012
Incredible if they can pull that off... some serious alignment and synchronisation required! Can't wait to see a picture one day, here's hoping it's a circle, I'm rooting for Einstein :-)

Jan 14, 2012
This comment has been removed by a moderator.

Jan 14, 2012
Will this picture be more like a family portrait or a vacation photo with someone making a rude gesture in the background?

Jan 14, 2012
When they take the picture they're going to see a guy in blue overalls holding the light breaker switch to "off"....

Jan 14, 2012
The title of this article, "Scientists gear up to take a picture of a black hole," lends the unfortunate impression with the public that it is possible to image a black hole. I would suggest that if you repeat such nonsense enough times, the public will come to believe it -- regardless of the philosophical problems inherent to observing black holes.

This problem strikes to the very heart of what's wrong with science today: Rather than being honest about the confines and limitations imposed by the dominant theory such that the public can make an honest assessment of the theory itself, we instead encourage theorists to come up with creative solutions which are not even wrong. We can spin our wheels in this state for generations, if you guys let it happen -- or, we can actually attempt to achieve some ideational fluency, and explore competing scientific frameworks.

Who here even knows what the emerging electrical framework inference is? And doesn't anybody here see this as a problem?

Jan 14, 2012
Research into creative problem-solving increasingly points to creative genius being a function of the breadth of ideational fluency. Genetics merely affects the chances of genius accidentally occurring. The bigger factor pertains to a person's willingness to hear out competing views. Consensus-driven science undermines ideational fluency, insofar as it invites agreement, to the detriment of a fluency in divergent arguments and worldviews.

What we need instead of consensus is convergence. Convergence is not forced; it self-assembles. It also easily accommodates divergence from conventional wisdom, permitting a much wider breadth of conversation than we see with this existing attempt at a coherent cosmology.

Conventional theorists still imagine that their consensus is not the product of social forces. And yet, theories are the products of people. So long as they persist with such blatant denial, our attempts to explain nature will continue to be pathetic.

Jan 14, 2012
Labeling everybody who disagrees with conventional wisdom as a "crank" represents a simplistic information filter. The problem of our era -- the Information Age -- is information overload. To excel in science, we must avoid the temptation to adopt simplistic information filters. In theory, the value of science is that all of our beliefs can be supported by arguments, observations and experimental data. Appeals to authority and ad hominem attacks are, in theory, irrelevant to this process. Those who look to these approaches to science -- as opposed to attempting to create their own ideational fluency -- will distract themselves into weak information filters. They will throw the baby out with the bathwater.

Simultaneously, those who are more concerned with fitting into a social fabric than tracking down truth in science will not care that they have done so.

This is how we can stall science. The social structure will then determine the results.

Jan 14, 2012
This group of radio astronomers are hoping to image our galaxies event horizon before Spectr R does. Spectr R is a russian radio interferometer almost the size of the orbit of the moon to the earth. If these event horizon group don't accomplish it, Spectr R will!

Jan 14, 2012
Incredible if they can pull that off... some serious alignment and synchronisation required! Can't wait to see a picture one day, here's hoping it's a circle, I'm rooting for Einstein :-)

Here's hoping it's somethinh else :-)

You see, if we just confirm existing theories - that's fine. But if we find something new - we find somthing new and that opens new and interesting possibilities.

Jan 14, 2012
I find it interesting that we have not mastered the detection of gravity waves yet. it is a shame too.I think that this would be the best way to see such things... just another pipe dream of mine.

Jan 15, 2012
Please. I need information: is there a scientifically proven fact that something or any situation can totally capture the light from which it never escapes? I remember that I ask a proven fact, not theory.

Jan 15, 2012
Morelli, learn english, then come back and ask question again.

Jan 15, 2012
is there a scientifically proven fact that something or any situation can totally capture the light from which it never escapes?
Black body absorbs most of light. The original energy is radiated back at different wavelengths, but the original light is gone for ever...

Jan 15, 2012
I thought this was an article on "porn of color" oh well.

Jan 15, 2012
I don't know, what the purpose of this article is. It's just rewritten seven years old story and nothing changed with astronomy from this time - the Hubble is still most powerful optical telescope in the same way, like before ten years.

Jan 15, 2012
Has anyone ever asked about or challenged the comment that a black hole is like water going down a drain? Does it spin clockwise or counter clockwise? On earth the direction it spins depends on which side of the equator you're on and at the equator it has no spin. Why would a black hole have a spin and if so why the direction it's going?
Which raises other question - is a black hole 3-dimensional? In other words what does it (reportedly or best guess!) look like - edge on?

Jan 15, 2012
These titles are made by attention whores. No journalism here.

Jan 15, 2012
@JLV, your claim about the spin direction of waterholes:

This is a common but absolutely groundless myth. Ask anyone who lives on or near equator. (BTW, just how near is near? Will 1m do? Or do we need to get to within 1mm of equator for the water to stop spinning?)

Jan 15, 2012
Why the black hole Sgr A* would have a spin is that the matter going in spinning in an accretion disk, and so has angular momentum that is conserved.

The black hole should be three dimensional, not just a disk. But a pure black circle will look like a pure black sphere. If there is asymmetry, it may be due to the spin and the distortion that produces in space-time nearby.

Jan 16, 2012
And not a mention of "Hawking Paradox", or "Hawking Radiation"? Would John Preskill, Leonard Susskind, Roger Penrose et al emerge happy, or would Hawking and Kip Thorne be vindicated?

Jan 16, 2012
The general theory has been questioned before

Jan 16, 2012
Morelli: The idea of a gravitational black hole has been around since the late 1700s, and doesn't require Einstein's theories. The more massive a solid object, the higher the escape velocity. Add enough mass and the escape velocity is greater than the speed of light.

No, it's not the same.

In classical (Newtonian) physics the force of gravity affects only objects with mass. Since light diesn't have any it is exempt and should escape no matter whay.

Having said that, classical physics had a lot of trouble explaining the properties of light (or even what is) anyway so the whole issue becomes moot.

Jan 16, 2012
Woot, I just discovered a bug on this site :-)

When I posted the above, the page came back with the article but no comments and the page number in the header which normally shows "2 / 2" was showing... "NaN / 2".

Considering what that NaN stands for (Not a Number coming from the FPU, for those who don't know) that's very clearly a bug.

Jan 18, 2012
The ALMA observatory in Chile has recently taken pictures of the Antennae galaxy 70 million light years away, why can't that telescope alone capture a picture of the black hole's event horizon 26,000 light years away?

Jan 19, 2012
@JLV @Grizzled It could very well have a spin (angular momentum), spin is a fundamental characteristic property of elementary particles, composite particles and atomic nuclei.

Jan 19, 2012
I didn't dispute that Borillion.

Jan 19, 2012
"The ALMA observatory in Chile has recently taken pictures of the Antennae galaxy 70 million light years away, why can't that telescope alone capture a picture of the black hole's event horizon 26,000 light years away?"

The resolving power of the ALMA array alone is insufficient to discern the event horizon in Sag A*, which has a much smaller apparent size than the Antennae galaxy(NGC 4038-39), despite the difference in distance. This is why very-long baseline interferometry (with an effective aperture of the Earth's diameter) is to be employed.

Jan 26, 2012
Why would a black hole have a spin and if so why the direction it's going?
The spin depends on that of the star collapsing to form the BH. Angular momentum is conserved on collapse so the spin after collapse would be much greater than before.

Jan 26, 2012
I find it interesting that we have not mastered the detection of gravity waves yet. it is a shame too.I think that this would be the best way to see such things... just another pipe dream of mine.
I think most matter has been in gravitational communication since it was created during inflation. This means we know the instantaneous gravitational field of all matter that hasn't been accelerated since its formation. Given we're in constant acceleration but updates to the gravitational field are transmitted at the speed of light. Moral of the story being what you detect gravitationally should be much closer to its actual position than it would be if you had to wait for its emission to arrive. So don't expect to find gravitational waves from visible objects at its position when its light was emitted. Anyway expect a whole new view of the actual universe much closer to real time than visual images.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more