People around the world cheered yesterday morning (Feb. 11) when scientists announced the first direct detection of gravitational waves — ripples in the fabric of space-time whose existence was first proposed by Albert Einstein, in 1916.

The waves came from two black holes circling each other, closer and closer, until they finally collided. The recently upgraded Laser Interferometer Gravitational Wave Observatory (LIGO) captured the signal on Sept. 14, 2015. Not every scientific discovery gets this kind of reception, so what exactly is all the hype about, and what's next for LIGO now that it has spotted these elusive waves?

First of all, detecting two colliding black holes is thrilling by itself — no one knew for sure if black holes actually merged together to create even more-massive black holes, but now there's physical proof. And there's the joy of finally having direct evidence for a phenomenon that was first predicted 100 years ago, using an instrument that was proposed 40 years ago. [Gravitational Waves Detected by LIGO: Complete Coverage]

But what is truly monumental about this detection is that it gives humanity the ability to see the universe in a totally new way, scientists said. The ability to directly detect gravitational waves — which are generated by the acceleration or deceleration of massive objects in space — has been compared to a deaf person suddenly gaining the ability to hear sound. An entirely new realm of information is now available.

"It's like Galileo pointing the telescope for the first time at the sky," LIGO team member Vassiliki (Vicky) Kalogera, a professor of physics and astronomy at Northwestern University in Illinois, told Space.com. "You're opening your eyes — in this case, our ears — to a new set of signals from the universe that our previous technologies did not allow us to receive, study and learn from."

"Up until now, we've been deaf to gravitational waves," LIGO Executive Director David Reitze, of the California Institute of Technology (Caltech), said during an announcement ceremony in Washington, D.C. "What's going to come now is we're going to hear more things, and no doubt we'll hear things that we expected to hear … but we will also hear things that we never expected."

With this new sensory view of the universe, here are some of the things scientists hope to discover.

Dark matter, dark energy: ESA and CERN set to unravel mysteries of the cosmos

https://youtu.be/C3FwXAz8DTg

New windows on the universe

LIGO is particularly sensitive to gravitational waves that come from violent cosmic events, such as two massive objects colliding or a star exploding. The observatory has the potential to locate these objects or events before light-based telescopes can do so, and in some cases, gravitational-wave observations could be the only way to find and study such events.

For example, in yesterday's announcement, scientists reported that LIGO had identified two black holes spinning around each other and merging together in a final, energetic collision. As their name suggests, black holes don't radiate light, which means they are invisible to telescopes that collect and study electromagnetic radiation. Some black holes are visible with light-based telescopes, because material in their immediate vicinity radiates, but scientists haven't seen examples of merging black holes with radiating material around them.

In addition, the black holes spotted by LIGO are 29 and 36 times the mass of the sun, respectively. But Reitze said that as LIGO's sensitivity continues to improve, the instrument could be sensitive to black holes that are 100, 200 or even 500 times the mass of the sun that are further away from Earth. "There could be a really nice discovery space that opens up once we get out there," he said.

Scientists already know that studying the sky in different wavelengths of light can reveal new data about the cosmos. For many centuries, astronomers could only work with optical light. But relatively recently, researchers built instruments allowing them to study the universe using X-rays, radio waves, ultraviolet waves and gamma-rays. Each time, scientists got a new view of the universe.

In the same way, gravitational waves have the potential to show scientists totally new features of cosmic objects, LIGO team members said. [Study of Gravitational Waves Could Unravel Many Mysteries (Video)]

"If we're ever lucky enough to have a supernova in our own galaxy, or maybe in a nearby galaxy, we will be able to look at the actual dynamics of what goes on inside the supernova," said LIGO co-founder Rainer Weiss of MIT, who spoke at the announcement ceremony. While light is often blocked by dust and gas, "gravitational waves come right out [of the supernova], boldly unimpeded," Weiss said. "As a consequence, you really find out what's going on inside of these things."

Other exotic objects scientists hope to study with gravitational waves are neutron stars, which are mind-bogglingly dense, burned-out stellar corpses: A teaspoon of neutron-star material would weigh about a billion tons on Earth. Scientists aren't sure what happens to regular matter under such extreme conditions, but gravitational waves could provide extremely helpful clues, because these waves should carry information about the interior of the neutron star all the way to Earth, LIGO scientists said.

LIGO also has a system set up to alert light-based telescopes when the detector seems to have spotted a gravitational wave. Some of the astronomical events that LIGO will study, such as colliding neutron stars, may produce light in all wavelengths, from gamma-rays to radio waves. With LIGO's alert system in place, it's possible that scientists could observe some astronomical events or objects in various wavelengths of light, plus gravitational waves, which would provide a "very complete picture" of those events, Reitze said.

"When that happens, that'll be, I think, the next big thing in this field," he said. 

Relativity

Gravitational waves were first predicted by Einstein's theory of general relativity, which was published in 1916. That famous theory has stood up to all kinds of physical tests, but there are some aspects that scientists haven't been able to study in the real world, because they require very extreme circumstances. The extreme warping of space-time is one example of this.

"Until now, we have only seen warped space-time when it is very calm — as though we had only seen the surface of the ocean on a very calm day, when it's quite glassy," Kip Thorne of Caltech, another founding member of LIGO and an expert on warped space-time, said at yesterday's ceremony. "We had never seen the ocean roiled in a storm, with crashing waves. All that changed on Sept. 14. The colliding black holes that produced these gravitational waves created a violent storm in the fabric of space and time." [The History & Structure of the Universe (Infographic)]

"This observation tests that regime beautifully, very strongly," Thorne continued. "And Einstein comes out with beaming success."

But the study of general relativity via gravitational waves is far from over. Questions remain about the nature of the graviton, the particle believed to carry the gravitational force (just like the photon is the particle that carries the electromagnetic force). And scientists have many questions about the inner workings of black holes, which gravitational waves may help illuminate (so to speak). But all of that, the scientists said, will be revealed slowly, over the course of many years, as LIGO and related instruments collect more data on more events.

A legacy for the future

Looking toward the next three years, Reitze said the collaboration is focused on increasing LIGO's sensitivity to its full potential. This will make the observatory — which consists of two big detectors, one in Louisiana and the other in Washington state — more sensitive to gravitational waves. But scientists don't know how many events LIGO will see, because they don't know how often many of these events occur in the universe.

LIGO detected the binary black hole merger even before the instrument began its first official observation campaign after its recent upgrade, but it's possible that this was a lucky break. To get the gravitational astronomy train rolling, LIGO simply needs more data.

When asked to comment on LIGO's impact on the world beyond the scientific community, and about how gravitational-wave science might influence people's daily lives, Reitze simply said, "Who knows?"

"When Einstein predicted general relativity, who would have predicted that we'd use it every day when we use our cellphones?" he said. (General relativity provides an understanding how gravity influences the passing of time, and this information is necessary for GPS technology, which uses satellites that orbit further away from the gravitational pull of the Earth than people on the surface).

LIGO is "the most sensitive instrument ever built," said Reitze, and the technological advances that have been made while building the observatory may feed into technologies that will be used in ways people can't yet predict.

Thorne said he sees the larger contribution of LIGO slightly differently.

"When we look back on the era of the Renaissance, and we ask ourselves, 'What did the humans of that era give to us that's important to us today?' I think we would all agree it's great art, great architecture, great music," he said.

"Similarly, when our descendants look back on this era, and they ask themselves, 'What great things came to us?' … I believe there will be an understanding of the fundamental laws of the universe and an understanding of what those laws do in the universe, and an exploration of the universe," Thorne added. "LIGO is a big part of that. The rest of astronomy is a big part of that. And I think that cultural gift to our future generations is really much bigger than any kind of technological spin-off, than the ultimate development of technology of any kind. I think we should be proud of what we give to our descendants culturally."

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

Before confirmation of the first direct observation of gravitational waves rippled through the world, the search had already begun for visible signs of the event that generated the powerful waves in space.

Two separate groups scanned the sky in the region where the historic discovery originated, in hopes of spotting light generated by the event.

"This first attempt to detect visible light associated with gravitational waves was very challenging, but it paves the way to a whole new field of astrophysics," Edo Berger of the Harvard-Smithsonian Center for Astrophysics said in a statement. [Stirred, Not Shaken - How Colliding Black Holes Make Waves]

Berger was the principal investigator of a team that used the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile to make a detailed search for the origination of the gravitational waves identified by the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Credit: By Karl Tate, Infographics Artist

Einstein's general theory of relativity predicts that the movement of massive bodies distorts the space-time through which they travel. Last week, scientists announced the first confirmed detection of such waves, produced by colliding black holes. The detection was kept under wraps until the results were verified and published in a scientific journal. But before announcing the news to the world, the scientists contacted two other teams already in place to follow up on any potential gravitational wave observations.

Berger's team made a detailed search of the region of sky where the preliminary signal was detected. The size of the area was daunting — 700 square degrees of sky, or about 2,800 times as large as the full moon — but astronomers combed the area thoroughly over a period of three weeks hoping to find a visible signal that corresponded to the crashing black holes. Although they did not detect any unusual bursts of visible light, their observations were used to place constraints on the brightness for future attempts.

At the same time, a second team used the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii to search for changes in the night sky. The instrument rapidly mapped the part of the sky where the signal originated. Computers then compared the new map to one made previously and identified any changed objects.

"We didn't find anything in our data that was likely related to the gravitational wave source," Stephen Smartt, director of the Astrophysics Research Centre at Queen's University Belfast and leader of the Pan-STARRS follow-up team, said in a separate statement. "We discovered over 50 new sources that are normal supernovae — exploding stars that we find all the time. We didn't see any hint of unusual behavior."

Back in September, researchers didn't yet know that the gravitational waves detected by LIGO were from two merging black holes, Berger told Space.com in an email. Black holes don't radiate light directly, and LIGO scientist Vicky Kalogera told Space.com that it seems unlikely there would be any matter near a black hole binary that would give off secondary light. But that doesn't mean people aren't looking.

There are "several new papers that come up with exotic scenarios" that could produce light from a double black hole merger, Berger said in an email.

"These papers are mainly driven by the LIGO discovery and I expect that more will show up in the coming days and weeks," he said. "Whether any of these theoretical ideas turn out to be correct is unclear at the present.  We will continue to observe future [binary black hole] mergers from LIGO to find out."

Like the observations made at Cerro Tololo, the Pan-STARR search will give scientists a little more information about what happened when the pair of black holes collided. Both teams stand ready to search again when LIGO makes its next detection. Gravitational waves can come from other sources besides a double black hole mergers, like exploding stars or the collision of two neutron stars (the dense, left-over cores of dead stars). Scientists know that most of those scenarios will generate light that telescopes could potentially detect.

"LIGO has opened a brand-new field of astronomy, and confirmation from facilities like Pan-STARRS will be very important to understanding them," Pan-STARRS Director Ken Chambers, an astronomer at the University of Hawaii, said.

Follow Nola Taylor Redd on Twitter @NolaTRedd or Google+. Follow us at @Spacedotcom, Facebookor Google+. Originally published on Space.com.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

When I was young, the only planets we knew about were the ones in our own solar system.

Astronomers presumed that many of the other stars in the night sky had planets too, but this was sheer speculation. We could never know for sure, the thinking went, because such planets were ridiculously small and faint. To ever see or study them seemed a complete impossibility. "Extrasolar planets," or "exoplanets," were a staple of science fiction, but not of professional astrophysics.

It's hard to believe that there was once such a simple time. The first definitive detection of an exoplanet was in 1991, identified by the tiny wobbles experienced by the parent star as its exoplanet swung around it. Since then, the field has exploded. There are now around 1,600 confirmed exoplanets, with almost 4,000 other known candidates. There are exoplanets smaller than Mercury, and others many times bigger than Jupiter. Their orbits around their parent stars range from a few hours to hundreds of years. And the ones we know about are just a tiny fraction of the approximately 100 billion exoplanets we now believe are spread throughout our Milky Way galaxy.

But while the golden age of exoplanets has barely begun, an exciting additional chapter is also taking shape: the hunt for exomoons.

Beyond Earth-like planets to exomoons

An exomoon is a moon orbiting a planet, which in turn is orbiting another star. You may not have ever heard of exomoons before now. But if you're a fan of films such as "Avatar," "Return of the Jedi" or "Prometheus," this should be familiar territory: in all three cases, most of the action takes place on an exomoon.

But what about real life? How many exomoons do we know of? At the moment, zero.

But the race is on to find the real-life analogs of Endor and Pandora.

You might think searching for tiny rocks orbiting distant planets around faint stars hundreds or thousands of light years away is the ultimate example of an obscure academic pursuit. But exomoons are poised to become a big deal.

The whole reason exoplanets are exciting is that they're a path to answering one of the grandest questions of all: "Are we alone?" As we find more and more exoplanets, we eagerly ask whether life could exist there, and whether this planet is anything like Earth. However, so far we've yet to find an exact match to Earth, nor can we yet really know for sure whether any exoplanet, Earth-like or otherwise, hosts life.

Enter exomoons in the search for life

There are several reasons why exomoons, these little distant worlds, may be the key to finding life elsewhere in the universe.

First, there's the stark reality that life on Earth may not have happened at all without the starring role played by our own moon.

The Earth's axis is tilted by 23.5 degrees relative to its motion around the sun. This tilt gives us seasons, and because this tilt is relatively small, seasons on Earth are mild: most places never get impossibly hot or unbearably cold. One thing that has been crucial for life is that this tilt has stayed the same for very long periods: for millions of years, the angle of tilt has varied by only a couple of degrees.

What has kept the Earth so steady? The gravity of our moon.

In contrast, Mars only has two tiny moons, which have negligible gravity. Without a stabilizing influence, Mars has gradually tumbled back and forth, its tilt ranging between 0 and 60 degrees over millions of years. Extreme changes in climate have resulted. Any Martian life that ever existed would have found the need to continually adapt very challenging.

Without our moon, the Earth, too, would likely have been subject to chaotic climate conditions, rather than the relative certainty of the seasons that stretches back deep into the fossil record.

The gravity of the moon also produces the Earth's tides. Billions of years ago, the ebb and flow of the oceans produced an alternating cycle of high and low salt content on ancient rocky shores. This recurring cycle could have enabled the unique chemical processes needed to generate the first DNA-like molecules.

Exomoons might have Earth-like environments

Overall, as we continue to hunt for another Earth somewhere out there, it seems likely that a twin of Earth, but without a moon accompanying it, would not look familiar. Finding exomoons is a key part of finding somewhere like here.

Meanwhile, we shouldn't be discouraged by the fact that most exoplanets found so far are bloated gaseous beasts, with hostile environments unlikely to support life as we know it. What we don't know yet, crucially, is whether these exoplanets have moons. This prospect is exciting, because exomoons are expected to be smaller rocky or icy bodies, possibly hosting oceans and atmospheres.

This is hardly speculation: Titan (a moon of Saturn) has a thick atmosphere even denser than Earth's, while underground oceans are thought to exist on Enceladus (another moon of Saturn) and on Europa and Ganymede (both moons of Jupiter). Thus, if there is any other life out there somewhere, it may well not be found on a distant planet, but on a distant moon.

The hunt is on. While exomoons are too faint to see directly, astronomers are deploying ingenious indirect techniques in their searches. Those moons are assuredly out there by the billions – and soon we will find them. It won't be too much longer before these tiny worlds help us answer huge questions.

Bryan Gaensler, Director, Dunlap Institute for Astronomy and Astrophysics, University of Toronto

This article was originally published on The Conversation. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Space.com .

EDITOR'S RECOMMENDATIONS

A new documentary airing on the Discovery Channel tomorrow (Feb. 20), looks at the construction of NASA's James Webb Space Telescope, and its place in a long line of universe-changing instruments.

"Telescope," a one-hour documentary, features interviews with many of the scientists involved with the James Webb Space Telescope (JWST), and footage taken at NASA's Goddard Spaceflight Center, where the movie's director, Nathaniel Kahn, has been filming and doing research for about two years.

The documentary succeeds in a task that is often taken for granted in science-oriented communications: It generates excitement in its audience. Viewers who may not have heard of JWST prior to viewing the film will likely walk away with a newly ignited curiosity about this massive telescope, what it might reveal about the cosmos and how it might change humanity's view of our place in the universe. [Photos of Hubble's Successor, the James Webb Space Telescope]

The impact of telescopes

"It's hard to predict the impact that [JWST] will have [on astronomy], because I think it's going to be so big," Amber Straughn, an astrophysicist at NASA Goddard, told Space.com.

Straughn, who is interviewed in "Telescope," is an extragalactic physicist, which means that she studies how stars and black holes form in distant galaxies. JWST, which is scheduled to launch in 2018, will help scientists study the very first galaxies to ever form in the universe, Straughn said.

Scientists will often talk about the "impact" that a new instrument will have on science, or even on all of humanity. But illustrating that point and convincing an audience that it is true can be extremely difficult, either because the answer is long and complex, and takes time to sink in, or because the "impact" isn't necessarily relevant to the viewer.

"Telescope" succeeds in showing that the use of telescopes has affected all of humanity, not just scientists, by changing what we know about the universe and our place in it.

"People take for granted that [the telescope], more than any other instrument in the history of innovation, has changed our sense of ourselves," Kahn told Space.com in an interview. "And it's done it not once, but many, many times."

Examples of this that are brought up in the film include the fact that telescopes played a critical role in showing humans that the Earth is not the center of the universe (or even the solar system). It wasn't until the 20th century that scientists had telescopes powerful enough to reveal the presence of other galaxies, providing the first real grasp of just how mind-bogglingly huge the universe is. It was telescopes that revealed evidence of the Big Bang, which at least partly answered the question, "Where did we come from?" or at least, "How long have we been here?" It was telescopes that revealed the presence of planets around other stars, and telescopes that may answer the question, "Are we alone?"  

"The history of telescopes is to teach us that we're not that special. It makes us less and less special every time we look at the universe and we learn there's much more out there than we thought before," Jason Kalirai, a project scientist for JWST says in the documentary.

Many documentaries cover this territory, but the central point can get lost amid too much additional information about the science or history of these events. "Telescope" doesn't bite off more than it can chew, or more than a "general" audience can swallow. While going over this telescopic history, it weaves in information about JWST, and illustrates how it will be another rung on this ladder from which humans can better see the size of the universe and their place in it.

Are we alone?

The aspect of JWST's science plan that has just about everyone on the edge of his or her seat is the study of exoplanets, and specifically, their atmospheres. JWST is an important part of the journey toward answering the question, "Are we alone?" and it will do amazing things. But I do harbor some concern that the documentary overhypes JWST's exoplanet-studying abilities, especially whether or not it could identify signs of life on an exoplanet.Astrophysicist Sara Seager says in the film that for JWST to detect signs of life on an exoplanet (which depends partly on what the telescope can do and partly on what is out there for it to find), is like "winning the lottery five times." To be clear, that is an effective "No," and viewers shouldn't misunderstand those odds. On the other hand, maybe there's nothing wrong with playing the lottery once in a while; maybe hoping for extreme odds is even essential in order for people to willingly invest in major projects like this one. 

Thankfully, JWST has much higher odds for what it will accomplish in other scientific pursuits, such as studying the very first galaxies to form in the universe. Because the light from the most distant galaxies in the universe takes billions of years to reach Earth, scientists see those galaxies as they looked billions of years ago — meaning that in some cases, the scientists will be able to see the very first galaxies in the universe, just as they were in the very early stages of their formation.

"The goal of studying those early galaxies is to sort of put together a picture or a story over time," Straughn told Space.com. "You're trying to progressively see how galaxies change over time. … We know that the earliest galaxies must be different from galaxies in the present-day universe."

Only hydrogen and helium (plus very small traces of a few other elements) existed in the early universe, so the first stars must have been made purely of hydrogen and helium. What kind of impact would that have had on how those galaxies looked and how they evolved?

"That epic of the first stars and galaxies is really what we're after with JWST," Straughn said.

But that's just the tip of the iceberg.

"The really great thing about telescopes like Webb is that they're such general-purpose observatories," Straughn said. "It's an observatory that will cover the entire breadth of the universe, from our own cosmic backyard of the solar system, all the way out to the most distant things that we can't even see yet."

The segments featuring people like Straughn, who speaks passionately and excitedly about JWST, are another strong point of "Telescope," and another element of science documentaries that can be taken for granted.

"As a documentary filmmaker, what you look for is people who are able to talk about what they know about, but who are also able to convey their humanity," Kahn told Space.com. Referring to the scientists he interviewed for the documentary, Kahn said, "Their passion [for] their subject and their life study is so infectious and so wonderful. When you start to probe that part of the scientists' minds and hearts, you suddenly open up this wellspring of marvelous drama, which is very exciting from a filmmaking standpoint to get at. Too often, science programming is trying to get all the information in — which is terribly important, we have to get that, too — but sometimes the emotion of the scientists themselves doesn't make it."

Kahn is an amateur telescope maker, and he got to know Matt Mountain because of his homemade telescope. Mountain, among other things, is the telescope scientist for JWST, and he is featured prominently in the film. Kahn began filming at Goddard two years ago, he said. During that time, he received some funding from the Northrop Grumman Foundation (Northrop Grumman is NASA's primary contractor for building JWST). Kahn began development of the documentary with Discovery channel about a year ago, a Discovery representative said.

"Telescope" is a well-done promotion for JWST that will convey to just about any viewer the reasons why people, not just scientists, should be excited about this instrument. While it is not an in-depth look at the science, technology or history of JWST, it does discuss the many, many ways that the mission could fail — for example, the telescope has to unfold from its cramped payload fairing, unfurling like a butterfly emerging from a cocoon. If any part of that unfolding process goes wrong, the telescope could be effectively useless. In addition, it orbits too far from home to be repaired by a space shuttle mission (if there were still any space shuttles). And the documentary does not pursue this question any further: What would it mean for NASA if an overbudget, multibillion-dollar project did not operate optimally, or not at all?

But those are heavy questions, and the consequences of a mission failure are best-explored when the potential benefits of the mission are fully understood as well. As I've said before in this essay, the ability to fully convey the potential awesomeness that JWST could beam down to Earth is not always easy. If "Telescope" seems like a simple look at this mission, it's because sometimes the simplest things take the most care to convey.

"I think to reach out into the dark and to discover things, one has to take risks," Kahn said. "I think that that's what great nations do, and what great scientists do: take risks. So of course it’s a high-stakes mission. But nothing dared, nothing gained.

"I think that it is missions like this that teach us to be bold, Kahn said. "Observing these people working together — it's given me courage, really honestly, in my own life. It's given me courage to be bold. Because I think that when you see people willing to spend years of their lives to build something that pushes the limits of what is possible, it's infectious. It's not enough to just get by. It's not enough to do what you did before. You have to push the limit of what you yourself are capable of," Kahn said.

"Telescope" will air on the Discovery Channel on Saturday, Feb. 20, at 9 p.m./8 p.m. Central. Check local listings.

Follow Calla Cofield @callacofield.Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.