Jeff Steinhauer, a physicist at Technion University in Israel, has created an acoustic black hole and observed particles slipping out of its grasp, providing the strongest evidence to date of one of Stephen Hawking's most famous predictions.
In 1974, Stephen Hawking predicted that black holes might not be the bottomless pits we imagine them to be. According to Hawking's calculations, some information might escape black holes in the form of energy, or Hawking radiation.
Here's how it works: Throughout the universe, matter-antimatter pairs of particles are constantly flickering in and out of existence (because matter and antimatter quickly annihilate each other). But if one of these particles is dragged into the event horizon of a black hole (the point where not even light can escape) before the pair annihilates, the other particle might slip away as Hawking radiation.
See Stephen Hawking through the years:
Stephen Hawking through the years
Stephen Hawking through the years
PRINCETON, NJ - OCTOBER 10: Cosmologist Stephen Hawking on October 10, 1979 in Princeton, New Jersey. (Photo by Santi Visalli/Getty Images)
Stephen Hawking (born in 1942), British mathematician and scientist, 1989. (Photo by Jean-Regis Rouston/Roger Viollet/Getty Images)
Professor Stephen Hawking poses for a photograph in his office at the University of Cambridge in Cambridge, U.K, in April 1991. Hawking has written countless scientific papers as well as books, receiving 12 honorary degrees and becoming Cambridge's Lucasian Professor of Mathematics, a post held by Sir Isaac Newton over 300 years earlier. (Photo by Bryn Colton/Getty Images)
SF.Hawking.1.bv.2Â5/PASADENA ÂÂ Theoretical physicist Stephen Hawking in his Cal Tech office. (Photo by Brian Vander Brug/Los Angeles Times via Getty Images)
(GERMANY OUT) - COL*08.01.1942-Physiker, Mathematiker, Grossbritannien- PortrÃ¤t (Photo by LS-PRESS/ullstein bild via Getty Images)
LONDON - DECEMBER 16: (EMBARGOED FOR PUBLICATION IN UK TABLOID NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Scientist Stephen Hawking and wife Elaine Mason arrive at the European Premiere of 'Lemony Snicket's A Series Of Unfortunate Events' at the Empire Leicester Square on December 16, 2004 in London. (Photo by Dave Benett/Getty Images)
OVIEDO, SPAIN: British astrophysicist Stephen Hawking gives his conference to open the XXV Prince of Asturias Awards Anniversary event in Oviedo, Northern Spain, 12April 2005. Stephen Hawking won the Prince of Asturias Award for Concord in 1989. AFP PHOTO / Miguel RIOPA (Photo credit should read MIGUEL RIOPA/AFP/Getty Images)
FRANKFURT, GERMANY - OCTOBER 19: Professor Stephen Hawking (L) and his wife Elaine Mason attend the international bookfair on October 19, 2005 in Frankfurt, Germany. South Korea is the guest of honour at the 57th annual Frankfurt Book Fair where 270.000 people are expected to visit the world's most important book fair, and 7000 exhibitors from 100 countries are present. (Photo by Ralph Orlowski/Getty Images)
FRANKFURT/MAIN, Germany: British physicist Stephen Hawking visits his German publisher Rowohlt's stand at the Frankfurt Book Fair 19 October 2005. The Frankfurt book fair opened its doors for the 57th time with the focus on authors from the Korean peninsula, but the presence of some 60 writers from the South and none from the North spoke as much of politics as literature. AFP PHOTO DDP/THOMAS LOHNES GERMANY OUT (Photo credit should read THOMAS LOHNES/AFP/Getty Images)
BEIJING, CHINA - JUNE 18: (CHINA OUT) Cosmologist Stephen Hawking visits the Temple of Heaven on June 18, 2006, in Beijing, China. Hawking has arrived in Beijing prior to his lecture at the Great Hall of the People today where he will discuss the origins of the universe at the Strings 2006 International Conference, hosted by the Chinese Academy of Sciences Institute of Theoretical Physics. The conference runs from June 19 ?24 at the Beijing Friendship Hotel. (Photo by ChinaFotoPress/Getty Images)
BEIJING - JUNE 19: (CHINA OUT) British scientist Stephen Hawking, delivers a lecture entitled 'The Origin of the Universe' at the Great Hall of the People June 19, 2006 in Beijing, China. British scientist Stephen Hawking is also visiting Beijing to attend the conference on the riddle of string theory which, if solved, could help unlock the mysteries of black holes and the creation of the universe, according to reports. (Photo by China Photos/Getty Images)
BEIJING - JUNE 21: British scientist Stephen Hawking attends a conference during the 2006 International Conference on String Theory on June 21, 2006 in Beijing, China. Hawking is visiting Beijing to attend the conference on the riddle of string theory which, if solved, could help unlock the mysteries of black holes and the creation of the universe, according to reports. (Photo by Cancan Chu/Getty Images)
JERUSALEM, -: British scientist Stephen Hawking is helped to turn his head as he arrives 10 December 2006 at the Israeli premier's offices to meet with Ehud Olmert in Jerusalem. Hawking is in Jerusalem for a lecture at the Bloomfield Museum of Science. AFP PHOTO/Yoav LEMMER (Photo credit should read YOAV LEMMER/AFP/Getty Images)
LONDON - JANUARY 17: Professor Stephen Hawking delivers his speech at the release of the 'Bulletin of the Atomic Scientists' on January 17, 2007 in London, Ebgland. A group of scientists assessing the dangers posed to civilisation have moved the Doomsday Clock forward two minutes closer to midnight as an indication and warning of the threats of nuclear war and climate change. (Photo by Bruno Vincent/Getty Images)
KENNEDY SPACE CENTER, UNITED STATES: British cosmologist Stephen Hawking(L) has his communication device adjusted by an aide at a pre-flight press conference 26 April 2007 at Kennedy Space Center, FLorida. Hawking, who has spent his career pondering the nature of gravity from a wheelchair, is set to experience weightlessness during a 'vomit comet' flight in Florida Thursday. The idea is to give 'the world's expert on gravity the opportunity to experience zero gravity' said Peter Diamandis the chief executive of the Zero Gravity Corporation. Hawking, 65, the British author of the blockbuster 'A Brief History of Time,' will be surrounded by a medical team on the padded plane as it flies a roller-coaster trajectory to produce periods of weightlessness. AFP PHOTO / ROBERT SULLIVAN (Photo credit should read ROBERT SULLIVAN/AFP/Getty Images)
KENNEDY SPACE CENTER, UNITED STATES: British cosmologist Stephen Hawking passes well wishers before boarding a plane 26 April 2007 at Kennedy Space Center, Florida. Hawking, who has spent his career pondering the nature of gravity from a wheelchair, is set to experience weightlessness during a 'vomit comet' flight in Florida Thursday. The idea is to give 'the world's expert on gravity the opportunity to experience zero gravity' said Peter Diamandis the chief executive of the Zero Gravity Corporation. Hawking, 65, the British author of the blockbuster 'A Brief History of Time,' will be surrounded by a medical team on the padded plane as it flies a roller-coaster trajectory to produce periods of weightlessness. AFP PHOTO / ROBERT SULLIVAN (Photo credit should read ROBERT SULLIVAN/AFP/Getty Images)
Professor Stephen Hawking gives a lecture entitled 'Why We Should Go Into Space' during the 50 Years of NASA lecture series at George Washington University in Washington, DC, April 21, 2008. AFP PHOTO/Jim WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)
South Africa former President Nelson Mandela (R) meets with British scientist Professor Stephen Hawking (L) in Johannesburg on May 15, 2008. Hawking, who has devoted his career to finding the origins of the universe, is in the country to begin a search for Africa?s answer to Einstein. Some of the world?s leading high-tech entrepreneurs and scientists have backed a ?75m plan to create Africa?s first postgraduate centres for advanced math and physics, after the British government declined to provide funding. AFP Photo/Denis Farrell / POOL (Photo credit should read DENIS FARRELL/AFP/Getty Images)
(FILES) British scientist Stephen Hawking attends the 2008 Cambridge Honnorary Degrees 2008's procession on June 23, 2008 at Cambridge University in east England. Renowned British astrophysicist Stephen Hawking has bet 100 dollars (70 euros) that a mega-experiment this week will not find an elusive particle seen as a holy grail of cosmic science, he said Tuesday September 9, 2008. In the most complex scientific experiment ever undertaken, the Large Hadron Collider (LHC) will be switched on Wednesday, accelerating sub-atomic particles to nearly the speed of light before smashing them together. AFP PHOTO/SHAUN CURRY/FILES (Photo credit should read SHAUN CURRY/AFP/Getty Images)
WASHINGTON - AUGUST 12: U.S. President Barack Obama (R) presents the Medal of Freedom to physicist Stephen Hawking during a ceremony in the East Room of the White House August 12, 2009 in Washington, DC. Obama presented the medal, the highest civilian honor in the United States, to 16 recipients during the ceremony. (Photo by Chip Somodevilla/Getty Images)
US President Barack Obama presents the Presidential Medal of Freedom to British theoretical physicist Stephen Hawking during a ceremony in the East Room at the White House on August 12, 2009. Obama awarded 16 individuals the 2009 Presidential Medal of Freedom, the highest civilian honor. AFP PHOTO/Jewel SAMAD (Photo credit should read JEWEL SAMAD/AFP/Getty Images)
PASADENA, CA - JANUARY 14: Scientist Stephen Hawking of 'Into The Universe With Stephen Hawking' speaks via satellite during the Science Channel portion of the 2010 Television Critics Association Press Tour at the Langham Hotel on January 14, 2010 in Pasadena, California. (Photo by Frederick M. Brown/Getty Images)
NEW YORK - JUNE 02: Physicist Stephen Hawking onstage during the 2010 World Science Festival Opening Night Gala at Alice Tully Hall, Lincoln Center on June 2, 2010 in New York City. (Photo by Jemal Countess/Getty Images)
Physicist Stephen Hawking attends the 2010 World Science Festival Opening Night Gala at Alice Tully Hall, Lincoln Center on June 2, 2010 in New York City.
LOS ANGELES - MARCH 9: 'The Hawking Excitation' -- When Wolowitz gets to work with Stephen Hawking (left), Sheldon (Jim Parsons, right) is willing to do anything to meet his hero, on THE BIG BANG THEORY, Thursday, April 5 (8:00-8:31 PM, ET/PT) on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LONDON, ENGLAND - AUGUST 29: Professor Stephen Hawking speaks during the Opening Ceremony of the London 2012 Paralympics at the Olympic Stadium on August 29, 2012 in London, England. (Photo by Dan Kitwood/Getty Images)
Theoretical physicist Stephen Hawking poses for a picture ahead of a gala screening of the documentary 'Hawking', a film about the scientist's life, at the opening night of the Cambridge Film Festival in Cambridge, eastern England on September 19, 2013. Hawking tells the extraordinary tale of how he overcame severe disability to become the most famous living scientist in a new documentary film premiered in Britain. AFP PHOTO / ANDREW COWIE (Photo credit should read ANDREW COWIE/AFP/Getty Images)
British actor Eddie Redmayne (R) pose with British scientist Stephen Hawking (L) at the UK premiere of the film 'The Theory of Everything' in London on December 9, 2014. The film is based on the memoir Travelling to Infinity: My Life with Stephen, by Jane Hawking, and stars Eddie Redmayne protraying the renowned astrophysicist Stephen Hawking. AFP PHOTO / JUSTIN TALLIS (Photo credit should read JUSTIN TALLIS/AFP/Getty Images)
LONDON, UNITED KINGDOM - DECEMBER 09: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Professor Stephen Hawking attends the UK Premiere of 'The Theory Of Everything' at Odeon Leicester Square on December 9, 2014 in London, England. (Photo by Max Mumby/Indigo/Getty Images)
LONDON, ENGLAND - FEBRUARY 08: Lucy Hawking and Stephen Hawking attend the EE British Academy Film Awards at The Royal Opera House on February 8, 2015 in London, England. (Photo by Samir Hussein/WireImage)
LONDON, ENGLAND - FEBRUARY 18: The world's best know scientist Professor Stephen Hawking takes VisitLondon.com's Official Guest of Honour Adaeze Uyanwah on a personal guided tour of his favourite places in the city's famous Science Museum on February 18, 2015 in London, England. On the tour Professor Hawking said he was pleased to lend his synthesised 'voice' to actor Eddie Redmayne for his Oscar-nominated performance in The Theory of Everything but added ' unfortunatley Eddie did not inherit my good looks.' (Photo by Tristan Fewings/Getty Images for London & Partners)
LONDON, ENGLAND - MARCH 30: (SUN NEWSPAPER OUT. MANDATORY CREDIT PHOTO BY DAVE J. HOGAN GETTY IMAGES REQUIRED) Stephen Hawking attends 'Interstellar Live' at Royal Albert Hall on March 30, 2015 in London, England. (Photo by Dave J Hogan/Getty Images)
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Acoustic black hole
To test this prediction, Steinhauer created an analogue black hole using extremely cold atoms trapped in a laser beam. When he applied a second laser beam, it made a sort of step that the atoms could flow over, kind of like a waterfall. As the atoms poured over the step, they accelerated, reaching supersonic speeds (faster than the speed of sound).
This created an acoustic black hole — sound waves inside the supersonic region couldn't escape because the condensate was flowing faster than the sound particles, or phonons, could travel. It's like trying to swim against river, Steinhauer explained to Business Insider. If the river is flowing faster than you can swim, then you can't move forward you go back. That's like this phonon trying to escape the black hole.
When pairs of phonons were created near the analogue black hole, Steinhauer observed one particle falling in and the other escaping. This, he said, is analogous to a photon escaping a real black hole.
In 2014, Steinhauer observed this Hawking radiation for the first time ever. But in that experiment, the radiation was simulated — it was caused by something hitting the event horizon and creating the pairs. These new results are the first observation of quantum Hawking Radiation, which means that the pairs were created all on their own out of nothing.
Steinhauer also observed something called entanglement between the two particles. Entanglement is a quantum connection of sorts between particles. Entangled particles are somehow connected regardless of the distance between them. So even if one particle falls into the black hole, the particle on the outside is still carrying the information of that particle.
This is the first time that anyone has ever produced evidence for entanglement between Hawking pairs.
Thinking about entanglement, Steinhauer said, is important to understanding something called the information paradox. According to quantum mechanics, information should never be lost. But as a black hole radiates Hawking radiation, it slowly evaporates until it disappears, along with all of the information inside of it. If entangled Hawking radiation on the outside carries the information of particles on the inside, it would explain what happens to all of that information.
"The reason people care about black holes and Hawking radiation is not to learn about the black holes themselves so much as to test the new laws of physics," Steinhauer said. "Verifying that Hawking radiation really occurs is a good step towards trying to figure out what the new laws of physics are."
In this experiment, Hawking radiation occurred in the form of extremely weak sound waves, with one wave on the outside and one on the inside. In order to see these very slight waves, Steinhauer had to repeat the experiment 4,600 times, which meant six days of continuous experiments. But the hard work paid off.
"We've verified Hawking's calculation and we've even seen that particles really are entangled," Steinhauer said. "I hope that this will give insight to physicists who think about real black holes."
Learn more about black holes:
Black holes are pretty freaking cool
Black holes are pretty freaking cool
A black hole, similar to V404 Cyg, devouring material from an orbiting star. Credit: ESO/L. Calçada
A computer simulation shows the collision of two black holes, a tremendously powerful event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO. LIGO detected gravitational waves, or ripples in space and time generated as the black holes spiraled in toward each other, collided, and merged. This simulation shows how the merger would appear to our eyes if we could somehow travel in a spaceship for a closer look. It was created by solving equations from Albert Einstein's general theory of relativity using the LIGO data.
This simulation was created by the multi-university SXS (Simulating eXtreme Spacetimes) project. For more information, visit www.black-holes.org.
(Photo via SXS)
The National Science Foundation (NSF) has announced the detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO), a pair of ground-based observatories in Hanford, Washington, and Livingston, Louisiana.
Albert Einstein predicted the existence of gravitational waves in his general theory of relativity a century ago, and scientists have been attempting to detect them for 50 years. Einstein pictured these waves as ripples in the fabric of space-time produced by massive, accelerating bodies, such as black holes orbiting each other. Scientists are interested in observing and characterizing these waves to learn more about the sources producing them and about gravity itself.
This is an artist's impression of gravitational waves generated by binary neutron stars.
(Photo via R. Hurt/Caltech-JPL)
This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity.
Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole's spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole's spin rate.
(Photo via NASA/JPL-Caltech)
This diagram shows how a shifting feature, called a corona, can create a flare of X-rays around a black hole. The corona (feature represented in purplish colors) gathers inward (left), becoming brighter, before shooting away from the black hole (middle and right). Astronomers don't know why the coronas shift, but they have learned that this process leads to a brightening of X-ray light that can be observed by telescopes.
Normally, before a black hole's corona shifts, there is already an effect at work called relativistic boosting. As X-ray light from the corona reflects off the black hole's surrounding disk of material -- which is traveling near half the speed of light -- the X-ray light becomes brightened, as seen on the left side of the illustration. This boosting occurs on the side of the disk where the material is traveling toward us. The opposite effect, a dimming of the X-ray light, occurs on the other side of the disk moving away from us.
Another form of relativistic boosting happens when the corona shoots away from the black hole, and later collapses. Its X-ray light is also brightened, as the corona travels toward us leading to X-ray flares.
In 2014, NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, and Swift space telescopes witnessed an X-flare from the supermassive black hole in a distant galaxy called Markarian 335. The observations allowed astronomers to link a shifting corona to an X-ray flare for the first time.
(Photo via NASA/JPL-Caltech)
In this artist's illustration, turbulent winds of gas swirl around a black hole. Some of the gas is spiraling inward toward the black hole, but another part is blown away.
A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
How Big Are Black Holes?
Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object.
(Artwork via NASA, and M. Weiss (Chandra X -ray Center))
Supermassive black holes at the cores of galaxies blast radiation and ultra-fast winds outward, as illustrated in this artist's conception. New data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton telescopes show that these winds, which contain gases of highly ionized atoms, blow in a nearly spherical fashion, emanating in every direction, as shown in the artwork. The findings rule out the possibility that the winds blow in narrow beams.
With the shape and extent of the winds known, the researchers were able to determine the winds' strength. The high-speed winds are powerful enough to shut down star formation throughout a galaxy.
The artwork is based on an image of the Pinwheel galaxy (Messier 101) taken by NASA's Hubble Space Telescope.
(Photo via NASA/JPL-Caltech)
A supermassive black hole is depicted in this artist's concept, surrounded by a swirling disk of material falling onto it.
(Photo via NASA/JPL-Caltech)
In July 2015, researchers announced the discovery of a black hole, shown in the above illustration, that grew much more quickly than its host galaxy. The discovery calls into question previous assumptions on the development of galaxies. The black hole was originally discovered using NASA's Hubble Space Telescope, and was then detected in the Sloan Digital Sky Survey and by ESA's XMM-Newton and NASA's Chandra X-ray Observatory.
Benny Trakhtenbrot, from ETH Zurich's Institute for Astronomy, and an international team of astrophysicists, performed a follow-up observation of this black hole using the 10 meter Keck telescope in Hawaii and were surprised by the results. The data, collected with a new instrument, revealed a giant black hole in an otherwise normal, distant galaxy, called CID-947.
(Illustration via M. Helfenbein, Yale University / OPAC)
Two black holes are entwined in a gravitational tango in this artist's conception. Supermassive black holes at the hearts of galaxies are thought to form through the merging of smaller, yet still massive black holes, such as the ones depicted here.
NASA's Wide-field Infrared Survey Explorer, or WISE, helped lead astronomers to what appears to be a new example of a dancing black hole duo. Called WISE J233237.05-505643.5, the suspected black hole merger is located about 3.8 billion light-years from Earth, much farther than other black hole binary candidates of a similar nature.
(Photo via NASA)
An extraordinary outburst produced by a black hole in a nearby galaxy has provided direct evidence for a population of old, volatile stellar black holes. The discovery, made by astronomers using data from NASA's Chandra X-ray Observatory, provides new insight into the nature of a mysterious class of black holes that can produce as much energy in X-rays as a million suns radiate at all wavelengths.
Researchers used Chandra to discover a new ultraluminous X-ray source, or ULX. These objects give off more X-rays than most binary systems, in which a companion star orbits the remains of a collapsed star. These collapsed stars form either a dense core called a neutron star or a black hole. The extra X-ray emission suggests ULXs contain black holes that might be much more massive than the ones found elsewhere in our galaxy.
(Photo via X-ray: NASA/CXC/Curtin University/R. Soria et al., Optical: NASA/STScI/ Middlebury College/F. Winkler et al.)
Did you know that a black hole could hurtle like a cannonball? Well, the Hubble Space Telescope found such an object – making this phenomena the image of the year in 2002. Astronomers were able to track the hole because it had a companion star – a black hole cannot be seen on its own because it swallows light. The theory is, which furthered by this image, that claims that black holes are created when a star dies in a violent supernova. (Photo via NASA)
The center of the Milky Way galaxy, with the supermassive black hole Sagittarius A* (Sgr A*), located in the middle, is revealed in these images. As described in our press release, astronomers have used NASA’s Chandra X-ray Observatory to take a major step in understanding why material around Sgr A* is extraordinarily faint in X-rays.
The large image contains X-rays from Chandra in blue and infrared emission from the Hubble Space Telescope in red and yellow. The inset shows a close-up view of Sgr A* in X-rays only, covering a region half a light year wide. The diffuse X-ray emission is from hot gas captured by the black hole and being pulled inwards. This hot gas originates from winds produced by a disk-shaped distribution of young massive stars observed in infrared observations.
These new findings are the result of one of the biggest observing campaigns ever performed by Chandra. During 2012, Chandra collected about five weeks worth of observations to capture unprecedented X-ray images and energy signatures of multi-million degree gas swirling around Sgr A*, a black hole with about 4 million times the mass of the Sun. At just 26,000 light years from Earth, Sgr A* is one of very few black holes in the universe where we can actually witness the flow of matter nearby.
(Photo via X-ray: NASA/UMass/D . Wang et al., IR: NASA/STScI)
This image, taken with the European Southern Observatory’s Very Large Telescope, shows the central region of galaxy NGC1313. This galaxy is home to the ultraluminous X-ray source NCG1313X-1, which astronomers have now determined to be an intermediate-mass black hole candidate. NGC1313 is 50,000 light-years across and lies about 14 million light-years from the Milky Way in the southern constellation Reticulum. (Photo via ESO)
Top: An illustration of NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, in orbit. The unique school bus-long mast allows NuSTAR to focus high energy X-rays.
Lower-left: A color image from NASA's Hubble Space Telescope of one of the nine galaxies targeted by NuSTAR in search of hidden black holes.
Bottom-right: An artist's illustration of a supermassive black hole, actively feasting on its surroundings. The central black hole is hidden from direct view by a thick layer of encircling gas and dust.