Einstein was right: gravitational waves exist

Photo by Amanda Pitts
Photo by Amanda Pitts
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Albert Einstein was right about one more thing: gravitational waves do exist in the universe.

On February 11, a team of physicists publicly confirmed that they heard and recorded the faint tone of two black holes colliding more than one billion light-years away — proving the presence of gravitational waves in the cosmos. This event represents the first direct evidence verifying Albert Einstein's theory of relativity.

According to the theory presented in 1916, when a pair of black holes orbit one another, they lose energy slowly, causing them to creep gradually closer. In the final minutes of their merger, they speed up considerably until finally moving at about half the speed of light. They then bash together, forming a larger black hole. A tremendous burst of energy is released, spreading through space as ripples in the curvature of spacetime in the form of waves.

Brett Bolen, professor of physics, said in Einstein's theory, space and time are united into one geometrical notion.

"Gravity is not thought of as a force, but as a bending of spacetime itself," Bolen said. "Space could be thought of as a rubber mat. If you put a large mass on that rubber mat, it bends the mat. If you roll a marble near the indention of the mat, the marble will seem to follow a curved path instead of a straight one."

According to the full report, when the black holes collided September 14, 2015, the event produced an energy 50 times greater than that of all the stars in the universe combined. That massive amount of energy vibrated a pair of L-shaped antennas in Washington State and Louisiana. The antennas are owned and operated by a worldwide team of scientists known as the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Bolen said the LIGO detection not only provides a new kind of test of general relativity, but it also gives astronomers new tools to explore the universe.

Richard Vallery, chair of Grand Valley's Physics Department, added that in the past, the universe has been explored almost exclusively through electromagnetic radiations, such as visible light, infrared, radiation and X-rays.

"Instruments like LIGO will allow us to 'look' at the universe in an entirely new way — by looking at the gravity that the interstellar objects emit," Vallery said. "As more observatories come online in the next few years, we will be able to get an even more detailed picture of the universe."

Vallery added that the LIGO experiment was unlike any seen up to this point.

"In order to detect these gravity waves, which are incredibly weak, we need extremely sensitive experiments," Vallery said. "In fact, the LIGO experiment needs to measure changes in length down to one-ten thousandth the size of a proton. At the time Einstein proposed gravity waves, we simply didn't have the technology to do an experiment with this sensitivity."

The full report, which includes more than 1,000 authors, can be viewed in Physical Review Letters.