Embry-Riddle Research Team Publishes Variation on Theory of Relativity

Embry-Riddle Aeronautical University researchers have developed a possible alternative to Einstein’s general theory of relativity as it relates to black holes, joining a movement among some physicists that looks to question the classical theory.

“The idea behind our project is to look at a model that slightly modifies Einstein’s equations,” Dr. Quentin Bailey, professor and program coordinator in the Department of Physics and Astronomy, said. “A lot of physicists don’t think that the general theory of relativity is the end of the story. They have proposed that Einstein’s equations work well, but maybe not in extreme regions of space-time, like black holes.”

The research, conducted by Bailey and two of his students, was published this year in Physical Review D, a peer-reviewed journal of the American Physical Society that covers significant developments in a number of scientific areas, including astrophysics.

Einstein’s general theory of relativity describes gravity as the result of mass and energy warping the fabric of space-time in the same way that a heavy ball on fabric would cause it to stretch from the ball’s weight, and a smaller ball then thrown on the fabric wouldn’t move in a straight line but would follow a curved path.

General relativity predicts that a massive collapsing star can form what is called a black hole, a region where the curvature of space and time is so strong that planets and rockets — and even light — cannot escape its gravity. Bailey pointed out that we know black holes exist because stars have been observed orbiting them. In 2015, gravitational waves produced when black holes collided were detected through research that won the Nobel Prize.

One of the reasons that general relativity is being questioned is that it does not align with quantum mechanics, the theory of the smallest particles of energy and matter. Equations developed to accommodate both general relativity and quantum mechanics don’t make sense mathematically, Bailey said.

“When we apply quantum mechanics to gravity, we get answers that don’t make sense, and we don’t know how to use them to make predictions,” he said.

Dario Walter-Cardona, a junior majoring in Space Physics, said the research is valuable to advancing our understanding of the universe.

“I think any theory heavy research is valuable, since it teaches us more about the nature of our current models by challenging them,” Walter-Cardona said. “Our belief that our current understanding of physics is correct relies on our attempts to disprove it.”

The theory that Bailey and his students investigated proposes that spacetime has a background field with a certain directional flow.

“That would modify Einstein’s theory,” Bailey said, “and the idea behind the project was to find out how. Was there anything we could try to measure in an experiment?”

The theory they explored is called the Bumblebee Model. It was given that name because it was once thought, erroneously, that bumblebees shouldn’t be able to fly, given their size and structure. The team’s model is extremely difficult to calculate, and is like the bumblebee in that you have to work hard to get it off the ground, Bailey said.

He said he coached student researcher Hailey Murray in how to do the calculations, adding that “it’s complicated mathematics, but she was able to do that as an undergrad. That’s a rare thing.”

This fall, Murray went on to a doctoral program in quantum computing at Cornell University. She has been awarded an extremely competitive National Science Foundation Graduate Research Fellowship Program grant.

In the team’s research, Bailey said that “we did find some interesting differences with Einstein’s general relativity theory, and we started to map those out” in the Physical Review D paper. “The particular model we’re working with represents a different direction from what other people have worked on.”

Walter-Cardona said working on the research has opened his path to becoming a theoretical physicist.

“Participating in this research has probably been the single best academic decision I’ve made since coming to Embry-Riddle,” Walter-Cardona said. “Playing a part in publishing a theoretical physics paper has not only made me feel more prepared to be a theoretical physicist, but it has also made me more excited to be one.”