SUMMARY: A black hole is a cosmic abyss with gravity of such intensity that nothing, not even light, escapes it. Now, for the first time, a team of astronomers has released an image of the space anomaly, which is created when a star collapses. Professor Brian Greene of Columbia University and the World Science Festival provides context and talks to Judy Woodruff about this scientific breakthrough.
SUMMARY: February saw one of the most important astronomical breakthroughs of the decade, as a team of scientists “heard” gravitational waves -- a key postulate of Einstein’s theory of relativity -- for the first time in human history. Now, astrophysicist Janna Levin recounts that incredible discovery, and the human drama behind it, in her new book “Black Hole Blues.” Levin joins Jeffrey Brown for more.
JEFFREY BROWN (NewsHour): The sound lasted about a fifth of a second, but it represented gravitational waves created by the collision of two black holes with the combined mass of about 62 of our suns a billion light years away.
“Black Hole Blues and Other Songs from Outer Space” is a story of things extraordinarily small and hard-to-comprehend large, and of the human drama in discovering them.
Author Janna Levin is a physicist and astronomer at Barnard College. She’s also author of a novel, “A Madman Dreams of Turing Machines.”
So, the blues, we’re sort of in the realm of metaphor here, but the idea is to hear the universe, at least as aspects that we can’t possibly see.
JANNA LEVIN, Author, “Black Hole Blues”: Yes, most of what we know about the universe really does come to us from light.
And we have telescopes that span the range of light to take pictures of the sky. This is utterly different. This is not a form of light. So when the black holes collided, they were like mallets on the drum. They rang space-time itself.
JEFFREY BROWN: But you have got to be able to hear them.
JANNA LEVIN: Right. So, you have to be able to record the shape of the drum.
And that’s basically what this experiment did. It recorded the shape of the ringing drum from two black holes that collided 1.3 billion years ago.
JEFFREY BROWN: All right, so step back and explain to us as simply as you can, what is a gravitational wave? And why is it important to our understanding of things?
JANNA LEVIN: Yes. Yes.
So, a gravitational wave is really a ripple or a change in the shape of space and time itself. So, if you were floating near these colliding black holes, you would literally be squeezed and stretched. And you would experience this squeezing and stretching. It emanates from this collision. It causes these ripples in space, kind of like fish swirling in a pond causing water waves.
And then they emanate out. They travel at the speed of light, even though they are not light. And eventually they make it here to the Earth. If you were floating nearby, you might even literally hear the wave, because your ear could respond to the vibrations.
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JANNA LEVIN: Well, I think what people don’t appreciate is, that’s really how science is done.
People think that we just come down with these answers. As scientists, we are full of answers. That’s really not what it is like. Scientists are full of questions. Sometimes, the questions don’t lead you to the answer, but, sometimes, they do, and there is this great discovery.
But, yes, there is fighting along the way. There is competition. There are failures and successes. And at the end of the climb, some people made it to the summit, and some people didn’t.
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| Simulation of Gravitational Lensing GIF by Alain r |
SUMMARY: Gravitational waves -- ripples in the fabric of spacetime -- aren’t just an Einstein theory any more. A team of international scientists announced Thursday that they confirmed the waves’ existence after recording feedback from a black hole collision a billion light-years from Earth. Hari Sreenivasan learns more from Dave Reitze of the California Institute of Technology.
HARI SREENIVASAN (NewsHour): Now some truly cosmic news.
The sound of two black holes colliding more than a billion years ago, it was recorded by a team of scientists at the LIGO Observatory, proof of gravitational waves, or ripples in time and space, first theorized by Albert Einstein.
We explore this monumental moment in physics with Dave Reitze of Caltech, executive director of the LIGO Laboratory.
Now, that was a rudimentary attempt at explaining what a gravitational wave is. But what are they, and why is it such a big deal to find one?
DAVID REITZE, California Institute of Technology: Actually, you did a pretty good job.
So, gravitational waves are fluctuations in space-time. And any time you have a mass, something that has matter in it, accelerating, all right, it produces a gravitational wave. All right? And that’s a consequence of Einstein’s Theory of General Relativity.
Now, these particular gravitational waves, in order to be able to detect them, you need really, truly massive objects. So, in this case, these were black holes that had about 30 times the mass of the sun in them.
So, why gravitational waves are so interesting is that they tell us something about the universe that you can’t get from any other kind of astronomy. So, if you think about optical astronomy, that looks at certain classes of light. If you look at radio astronomy — so gravitational waves are completely different.
They come from a different sector of the universe, and that’s why they’re so exciting.
HARI SREENIVASAN: OK. So Einstein is sitting at his patent clerk’s office thinking about this big thought, and what is the connection to space-time?
DAVE REITZE: Yes.
HARI SREENIVASAN: Does time and space bend? And if you heard or saw, so to speak, this moment, does that mean that time and space bent just a little bit at those points?
DAVE REITZE: Oh, in fact, this particular event was, as my colleague Kip Thorne calls it, a storm in space-time.
All right? As these two black holes came together and collided, they really disrupted space-time and produced this burst of gravitational radiation. It’s interesting that you mention Einstein. Gravitational waves were first predicted actually 100 years ago. And Einstein himself, all right, thought it was an interesting consequence of the theory of relativity, but didn’t think that it had any practical value, because he said that the effect is so tiny that we will never be able to measure them.
And it took 100 years from the time that he predicted them to the time we have been able to measure them.
GWEN IFILL (NewsHour): An amazing scientific search pushing the limits of what we know about the cosmos, the quest to see a black hole.
The “NewsHour's” Rebecca Jacobson went to Chile for this report.
SHEP DOELEMAN, Principal investigator, Event Horizon Telescope: Black holes are some of the most exotic objects in the universe. They come about when matter gravitationally collapses in on itself, and everything becomes pulverized and crushed down into a single point.
REBECCA JACOBSON (NewsHour): MIT astronomer Shep Doeleman is leading an international effort to understand black holes. These exotic objects are fundamental to our understanding of the universe. When stars, dust, and planets cross the event horizon surrounding the black hole, nothing, not even light, can escape. But no one has ever seen one.
Doeleman is trying to change that.
SHEP DOELEMAN, MIT: The Event Horizon Telescope project is really about seeing what we have always thought as unseeable.
REBECCA JACOBSON: But to boldly go where no telescope has gone before, scientists have to drive up a 16,500 foot-high mountain. This is the Atacama Large Millimeter, or ALMA, in Northern Chile. ALMA’s 66 antennas form the most powerful radio telescope in the world.
Each antenna weighs 100 tons, and they are so accurate, they can see a golf ball nine miles away. They will form the anchor for the Event Horizon Telescope, a worldwide network of observatories that will capture an image of a black hole for the first time.
ALMA’s antennas sit just 400 feet lower in elevation than Mount Everest’s North Base Camp. Before going up the mountain, we had to undergo rigorous physical testing, because working at this altitude is dangerous.
My blood pressure was a little too high, so we waited a few minutes to see if it would go down.
The mass that Sagittarius A* spits back out explain why there is such a dim-looking black hole in the center of our galaxy.
The colossal black hole at the heart of the Milky Way galaxy is a messy eater. Of all the gas that falls toward the black hole, 99 percent gets spewed back out into space, new observations show, making the black hole akin to a toddler whose food ends up mostly on the floor, rather than his mouth.
The Milky Way's supermassive black hole, called Sagittarius A* (pronounced "Sagittarius A-star"), contains the mass of 4 million suns. Yet it's not getting much larger, according to the new findings, which help explain why the object is surprisingly dim.
Although black holes themselves can't be seen, their immediate vicinities usually emit strong radiation from the material falling into them. Not so for Sgr A*, though, which has prompted a rash of competing theories trying to explain its surprising lack of light. [Strangest Black Holes In the Universe]
"There's been a debate for the last 20 years or so about what actually is happening to the matter around the black hole," said research leader Q. Daniel Wang of the University of Massachusetts, Amherst. "Whether the black hole is accreting the matter, or actually whether the matter can be ejected. This is the first direct evidence for outlflow in the accretion process."
The new findings show definitively that most of the matter in the gas cloud surrounding the black hole is ejected out into space, which explains why it doesn't release light on its way in to be eaten.
3 million seconds
The discovery comes via new observations taken by NASA's Chandra X-Ray Observatory that required the equivalent of about five weeks of observing time (Wang gave the amount of time as 3 megaseconds, or 3 million seconds), spread out over months, to achieve unparalleled resolution of the area around Sagittarius A*.
The X-ray views focused on the cloud of hot gas surrounding the black hole, and found that there was much less higher-temperature gas than lower-temperature gas there. Because mass heats up as it falls toward a black hole, the researchers were able to infer that gas was being lost during this process. "There must be ejection of matter when the gas is moving in," Wang explained.
"Exactly how it happens is not totally clear," Wang told SPACE.com. "There are all kinds of simulations and theories which predict that it should occur. But this is the first observational evidence that can say this does occur."
Scientists still have a ways to go to see the area in enough detail to decipher the mechanism for the gas ejection, he said. They also don't yet know where all this gas goes, he added.
Ruled out theories
The new observations definitively rule out some theories that had attempted to explain the perplexing dimness of Sgr A*, such as one idea that most of the light there was being emitted by a potential group of rapidly rotating low-mass stars.
Wang and his colleagues' findings are detailed in the Aug. 30 issue of the journal Science.
"This result is important not only for Sgr A*, but also all other low-luminosity black holes, since we now have a better understanding of their radiative efficiency, i.e., how to relate the light that we see to the amount of gas actually getting accreted onto the black hole," astrophysicist Jeremy Schnittman of NASA's Goddard Space Flight Center in Greenbelt, Md., wrote in an email. Schnittman was not involved in the research, but wrote a commentary article on the findings published in the same issue of Science.
The new data also offer some evidence for where the gas cloud comes from. The Chandra observations show its shape in better detail than ever before, and suggest that it closely mirrors the distribution of a group of massive stars previously seen there, which have formed a disc. Massive stars are known to emit strong winds of material that fly out at superfast speeds. Wind from these stars is likely colliding, producing the hot plasma of gas found around the black hole, Wang said.
Many of the researchers ideas about Sagittarius A* can be further tested in the coming months when a rare event occurs. A small cloud of gas is on a collision course with the black hole, and is due to be gobbled up before scientists' eyes. Because this cloud is made of cold and not hot gas, it's expected to be almost fully consumed by Sagittarius A*.
"It will be really interesting to see what happens when the G2 cloud approaches later this year," Schnittman told SPACE.com in an email. "Will the efficiency change when the accretion rate goes up? Is there an abrupt transition to a new type of accretion? Will we see anything different at all?"
Stay tuned!
Living up to its name, NASA's WISE (Wide-field Infrared Survey Explorer) telescope has uncovered millions of black holes and extreme galaxies across the universe.
Recently released images from the telescope reveal millions of dusty black hole candidates, as well as about 1,000 even dustier objects, which scientists believe are among the brightest galaxies ever discovered, and which have appropriately been nicknamed "hot DOGs," or dust-obscured galaxies.
"WISE has exposed a menagerie of hidden objects," WISE program scientist Hashima Hasan said in a statement. "We've found an asteroid dancing ahead of Earth in its orbit, the coldest star-like orbs known and now, supermassive black hole galaxies hiding behind cloaks of dust."
Last year, the telescope put on its night-vision goggles to twice scan the entire sky with infrared light, capturing millions of images that allowed scientists to dig around for new discoveries.
Black holes had better watch their backs, said Daniel Stern, lead author of the WISE black hole study and member of NASA's Jet Propulsion Lab. By combining projects, the WISE telescope can find the monstrous black holes, while the Nuclear Spectroscopic Telescope Array (NuSTAR) provides a new look at their high-energy X-ray light, Stern said.
NASA launched the black-hole hunting NuSTAR in mid-June, which sported a telescope that can see the hottest, densest, most energetic objects, Fiona Harrison, NuSTAR principal investigator at the California Institute of Technology, said in June.
In one case, NASA's device helped astronomers identify about 2.5 million actively feeding supermassive black holes, reaching more than 10 billion light-years away, the space association said in a news release. Generally, dust blocks the objects' visible light, NASA said, but WISE sees their warm dust glowing in infrared light.
One of the main goals of the WISE mission was met when scientists reported finding what they believed were among the brightest galaxies ever known. Despite emitting more than 100 trillion times as much light as the sun, NASA said the DOGs are so dusty that they appear only in the longest wavelengths of infrared captured by WISE.
In this case, the galaxies' eggs may have come before the chickens, WISE project scientist at JPL Peter Eisenhardt said. The lead author of a paper on the first of the DOGs, Eisenhardt said there may be evidence to prove that the galaxies formed their black holes before most of their stars.
"We may be seeing a new, rare phase in the evolution of galaxies," JPL's Jingwen Wu said in a statement.
All three published technical journal articles can be found online.
More than 100 of the objects located by WISE have been confirmed with the W.M. Keck Observatory in Hawaii, as well as the Gemini Observatory in Chile, Palomar's Hale telescope near San Diego, and the Multiple Mirror Telescope Observatory near Tucson, Ariz., according to NASA.
For more, see the NASA video below, which simulates billions of years of evolution, which created the millions of black holes that WISE helped to discover.
NASA on Wednesday launched its newest X-ray space telescope on a mission to shine a light on black holes and other hard-to-see objects lurking in the Milky Way and other galaxies.
Mission controllers clapped after receiving a signal from the telescope that it had reached orbit 350 miles above Earth.
"It's a terrific day," assistant launch director Tim Dunn said.
NASA decided to air-launch the $170 million mission, instead of rocketing off from a launch pad, because it was cheaper. The telescope was boosted into orbit by a Pegasus rocket released from a carrier aircraft that took off from the remote Kwajalein Atoll, a horseshoe-shaped Pacific island halfway between Hawaii and Australia.
After free-falling for several seconds, the rocket ignited its engines and climbed to space. Minutes later, the telescope separated from the rocket and unfurled its solar panels as it circled 350 miles above the Earth.
The Nuclear Spectroscopic Telescope Array, or NuStar for short, focuses high-energy X-rays to peer through gas and dust in search of supermassive black holes in the center of galaxies, remnants of exploded stars and other exotic celestial objects.
While black holes are invisible, the region around them gives off telltale X-rays. NuStar will observe previously known black holes and map hidden ones. By zeroing in on never-before-seen parts of the universe, scientists hope to better understand how galaxies form and evolve.
"We can view black holes and galaxies even if they're enshrouded with dust and gas. If you had high-energy X-ray eyes and you stared up out of the galaxy, what you would see is the glow of all the massive black holes sprinkled throughout the cosmos," chief scientist Fiona Harrison of the California Institute of Technology said earlier this week.
NuStar will also hunt for the remains of ancient supernovae, stars that exploded in past centuries. If it's lucky, it'll witness a star's death throes, but such events don't happen often and the telescope will have to be pointed at the right place at the right time.
Scientists expect sharp images from the mission, which is many times more sensitive than previous space telescopes that have looked in this part of the electromagnetic spectrum.
After a week in orbit, NuStar will unwrap its 33-foot mast laden with sensors. Observations will begin about a month after launch.
The mission was supposed to lift off in March, but was delayed by a flight software issue with the rocket. To keep costs down, project managers bypassed the launch pad, which would have required a much larger rocket.
The launch comes at a trying time for NASA's astrophysics division. Last week, the space agency killed an X-ray telescope mission because it failed to come in on budget. That mission, called GEMS, was supposed to launch in 2014 and would have observed many of the same targets as Nustar.
NASA is pressing ahead with its flagship astrophysics mission — the budget-busting James Webb Space Telescope considered the successor to the Hubble Space Telescope. It has the capability of peering deeper into the universe and back in time than ever, and is expected to launch in 2018 with an $8 billion price tag.
GWEN IFILL (Newshour): ....they're big, they're scary, and, lucky for us, they're about 300 million light years away.
We're talking about the largest black holes in the universe, and nothing, not even light, can escape their gravitational pull. Astronomers recently discovered two black holes, each one 10 billion times the size of our sun. Their findings are being reported this week in the journal "Nature."
Joining me now is Chung-Pei Ma. She is a professor of astronomy at the University of California, Berkeley, and led the team that published the study.
An artist's conception of stars moving in the central regions
Astronomers are reporting that they have taken the measure of the biggest, baddest black holes yet found in the universe, abyssal yawns 10 times the size of our solar system into which billions of Suns have vanished like a guilty thought.
Such holes, they say, might be the gravitational cornerstones of galaxies and clues to the fates of violent quasars, the almost supernaturally powerful explosions in the hearts of young galaxies that dominated the early years of the universe.
One of these newly surveyed monsters, which weighs as much as 21 billion Suns, is in an egg-shaped swirl of stars known as NGC 4889, the brightest galaxy in a sprawling cloud of thousands of galaxies about 336 million light-years away in the Coma constellation.
The other black hole, a graveyard for the equivalent of 9.7 billion Suns, more or less, lurks in the center of NGC 3842, a galaxy that anchors another cluster known as Abell 1367, about 331 million light-years away in Leo.
“These are the most massive reliably measured black holes ever,” Nicholas J. McConnell, a graduate student at the University of California, Berkeley, said in an e-mail, referring to the new observations.
These results are more than just cool and record-setting. Observations with the Hubble Space Telescope over the years have shown that such monster black holes seem to inhabit the centers of all galaxies — the bigger the galaxy, the bigger the black hole. Researchers said the new work could shed light on the role these black holes play in the formation and evolution of galaxies.
The most Earth-like planet ever discovered is circling a star 600 light years away, a key finding in an ongoing quest to learn if life exists beyond Earth, scientists said on Monday.
The planet, called Kepler-22b, joins a list of more than 500 planets found to orbit stars beyond our solar system. It is the smallest and the best positioned to have liquid water on its surface -- among the ingredients necessary for life on Earth.
"We are homing in on the true Earth-sized, habitable planets," said San Jose State University astronomer Natalie Batalha, deputy science team lead for NASA's Kepler Space Telescope that discovered the star.
The telescope, which was launched three years ago, is staring at about 150,000 stars in the constellations Cygnus and Lyra, looking for faint and periodic dimming as any circling planets pass by, relative to Kepler's line of sight.
Results will be extrapolated to determine the percentage of stars in the Milky Way galaxy that harbor potentially habitable, Earth-size planets.
This is the first detection of a potentially habitable world orbiting a Sun-like star, scientists reported in findings to be published in The Astrophysical Journal.
Kepler-22b is 600 light years away. A light year is the distance light travels in a year, about 6 trillion miles (10 trillion km).
GROUND TELESCOPES
Planets about the same distance from their parent stars as Earth take roughly a year to complete an orbit. Scientists want to see at least three transits to be able to rule out other explanations for fluctuations in a star's light, such as small companion stars. Results also are verified by ground and other space telescopes.
Kepler-22b, which is about 2.4 times the radius of Earth, sits squarely in its star's so-called "habitable zone," the region where liquid water could exist on the surface. Follow-up studies are under way to determine if the planet is solid, like Earth, or more gaseous like Neptune.
"We don't know anything about the planets between Earth-size and Neptune-size because in our solar system we have no examples of such planets. We don't know what fraction are going to be rocky, what fraction are going to be water worlds, what fraction are ice worlds. We have no idea until we measure one and see," Batalha said at a news conference at NASA Ames Research Center in Moffet Field, California.
If Kepler-22b has a surface and a cushion of atmosphere similar to Earth's, it would be about 72 degrees Fahrenheit (22 C), about the same as a spring day in Earth's temperate zone.
Among the 2,326 candidate planets found by the Kepler team, 10 are roughly Earth-size and reside in their host stars' habitable zones.
Another team of privately funded astronomers is scanning the target stars for non-naturally occurring radio signals, part of a project known as SETI, or the Search for Extraterrestrial Intelligence.
"As soon as we find a different, a separate, an independent example of life somewhere else, we're going to know that it's ubiquitous throughout the universe," said astronomer Jill Tarter, director of the SETI Institute in Mountain View.
The Kepler team is meeting for its first science conference this week.
