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Sunday, May 19, 2024

Putting Einstein to the test

Albert Einstein is one of the most respected scientists of all time. His ideas and theories have changed the way that physicists view the universe. Some of his ideas were so ahead of their time that there has never been a way to prove or disprove them.  However, with a recent discovery of a new star near the center of our galaxy, scientists may finally be able to prove, or disprove, the famous theory of relativity.

The star, named S0-102, orbits the black hole found in the center of the Milky Way galaxy every 11.5 years, five years faster than S0-2, the next closest star to the galactic core that was previously being studied by Andrea Ghez, leader of the UCLA research group that made the discovery. However, the record-breaking orbit is not the most exciting part of the discovery.

“The [more] important thing is that we have found a second star that orbits the black hole in a human lifespan,” said Leo Meyer, a researcher in Ghez’s team. “Most of those stars take more than a hundred years to orbit around [the black hole] and this is just too long.”

Ghez explained that each star on its own is not incredibly useful, but now that two stars can be observed, the interactions of these two stars will reveal how space and time warp around black holes.

Since the orbit completes in a human time-frame, more accurate observations can be made because researchers can view multiple complete cycles instead of just a partial cycle of a star that orbits every hundred or so years. The information given by the orbits will help astronomers learn how much space is affected by the gravity of the supermassive black hole.

“This theory is by far the least tested and so we can use this discovery to test Einstein in a fundamentally new way,” said Meyer.

Using observations of this new star, astronomers at UCLA hope to test Einstein’s theory of general relativity, which predicts that mass distorts space and time in the way a bowling ball would distort a mattress. Of course, this distortion in space would be in three dimensions instead of a two-dimensional mattress. Einstein’s theory has been tested on stars and planets, but it has never been proven to work in or near a supermassive black hole.

“Einstein’s theory has been very precisely tested inside of our own solar system, and so far it has passed all tests we have thought of,” said Andrew Bradshaw, a graduate student in the department of physics at UC Davis. “The strength of gravity around our Sun is weak in comparison to gravity around the black hole. By precisely measuring the orbits of stars like S0-2 and S0-102, [astronomers] will be able to test whether the measurements match the predictions made by Einstein.”

The newly-found star is significant to the research because it gives astronomers valuable information about other objects that orbit near the center of the Milky Way galaxy, and it will help determine what the mass of a black hole actually is — a question that has taunted astronomers for generations.

“When an astronomer wants to figure out the mass of an object, for instance, the black hole at the center of the galaxy, we always learn what an object’s mass is by measuring its gravitational influence on other objects,” said Robert Becker, a professor in the UC Davis physics department and a member of the UC Davis Cosmology Group.

With the discovery of this new star orbiting so close to the galactic core, astronomers will now be able to make far more accurate calculations about the properties of the black hole at the center of our galaxy.

UCLA is currently developing new technology to increase the sensitivity of telescopes, thus revealing any more large bodies in the gravitational field of the central black hole. Ultimately, the research will lead to more information about the enigmatic properties of black holes.

“[Researchers are] clearly learning to do this better, and one of the results of that is being able to see fainter stars … as you go to fainter stars, you see more stars,” Becker said. “[This] is only the tip of the iceberg as they improve their techniques to better map out the stars in the vicinity of the black hole, and better define what the state of things is at the center.”

NICOLE NOGA can be reached at science@theaggie.org.


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