Gravitational waves from the collision of two black holes have come to Earth. This is not exactly a local story: The waves emanated from a galaxy far, far away—about a billion light years, to be more or less precise. But scientists from New York’s Columbia University are part of a team that detected the waves.
What does all this mean? Muna Habib of NY City Lens spoke to one of the Columbia scientists, Imre Bartos, lead researcher and lecturer in the university’s Physics department. Bartos worked on his part of the project with other astrophysicists, Szabolcs Marka and Zsuzsanna Marka.
This Q&A is based on the interview with Bartos.
Q: Is this a big deal? Should we be excited?
The discovery confirms the nature of black holes, and that proves Albert Einstein’s General Theory of Relativity. “Some secrets about the universe will be unblocked because of this discovery,” Bartos said. He described the impact of the discovery on science this way—as if a deaf person suddenly had the ability able to hear. The discovery opens up a new window to how scientists investigate the universe. Before we could only see the light from the universe, now we can “hear” the universe.
Q: So what is a gravitational wave?
A gravitational wave is a ripple in the fabric of space- time, produced whenever mass accelerates and changes the distortion of space-time. The ripples are detected using the Laser Interferometer Gravitational Wave Observatory, or the LIGO. The team from Columbia built the important sensors in LIGO that detect changes in the gravitational waves. They are members of the LIGO Group, a global team of more than a thousand scientists that includes scientists from the United States and Europe.
How does LIGO work?
The $1 billion magic machine called the Laser Interferometer Gravitational-Wave Observatory is made up of two sets of long tunnels—one in Washington State and the other in Louisiana. The tunnels contain sensors that are made using the speed of light as a marker. When the gravitational waves pass through the ultra sensitive detector in LIGO they change the length of light. The sensors in LIGO are kind of a ruler—one that measures the changes in the length of light. If the point between the two ends is stretched, the light will take longer to travel. If shortened, the time required to travel in between two points is reduced. The light sensors detect the time difference taken for light to travel.
Q. How might this new knowledge be applied?
One of the critical applications of the discovery will be to understand supernovas, or enormous exploding stars. The matter from exploding stars feed the cosmos with elements like carbon, oxygen, and nitrogen before they become detectable with telescopes.
After the explosion, the light and elements try to escape, but they are blocked by the debris from the star. The gravitational waves don’t get stuck, however—they pass through and reach Earth. Thus the gravitational waves can reach Earth faster than light.
The small perturbations of gravitational waves reaching the earth provide clues to the reason for the explosions. The hidden boiling centers of supernovas are observed, as the gravitational waves emanating from them contain encoded information about their origins. And by understanding this, scientists can better explain the universe and where it came from. “At the moment the only tools to explore what happens inside supernovas are computer models,” said Bartos
Gravitational waves were thought to be born 13.8 billion years ago, according to the Big Bang Theory.
Q: How does Einstein get into the picture?
Einstein’s theory explains how objects move through space. Einstein said gravity is the result of mass objects manipulating the fabric of space-time. The concepts introduced by his theory of relativity include the idea of space-time as space and time unified throughout the universe, something akin to how a six-mile run takes a good runner one hour.
Q: Huh. What about time travel, then?
Bartos said, “black holes are already good for time travel.” He explained that if you get close to a back hole and get away, then you have already moved into the future. If a space ship orbits a black hole, time on the space ship will pass slower than for someone far away from the black hole. This means those who orbit a black hole for a while and then come away, will experience less time passed than others who stayed away. “On Earth time passes slightly slower than in outer space.” Bartos said,
So in principle, he said, it is possible to travel into the future with black holes. Sadly, going into the past is still not possible. Why? Don’t ask.
Q: Does the discovery of the gravitational waves have practical implications?
The advances made in scientific research by the study of black holes are already being applied to medicine and science, Bartos said, and will continue to be. They are in the process of building the most sensitive detectors ever, the team has already advanced human lives. For example: Bartos explained that his team had developed a light wall that uses optic lights. The light shield also happens to protect humans from insects; dangerous mosquitos like those transmitting the Zika virus could be kept away from humans using this technology.The light shield is still in its prototype phase, but is an example of “how the study of black holes helps humanity,” Bartos said.