Harvey Mudd physics professor Vatche Sahakian spoke Tuesday about a new theory of gravity that could revolutionize modern physics if proven correct.

Sahakian’s colloquium at Harvey Mudd’s Galileo Hall drew more than 100 students and professors. This installment of the colloquium series aimed to open conversation on campus about an idea that is currently puzzling world-class physicists.

Sahakian used his lecture to explain a controversial paper published this year by Dutch physicist Erik Verlinde, who argues that gravity is not a fundamental force but an “entropic force,” or a particle behavior explained by nature’s tendency toward disorder. Verlinde’s paper is the latest high-profile attempt to solve a problem that has vexed physicists for decades.

“This picture of gravity that we have is not fundamental. We really don’t know what gravity is,” Sahakian said at the colloquium. “It is almost as if we’re flirting with a deep principle, but we can’t put our finger on it.”

Verlinde proposes that physicists have been studying gravity incorrectly by placing it in the same category as fundamental forces like electromagnetic force. Instead, he argues, physicists should think of gravity as an “emergent force”—that is, a phenomenon that causes acceleration but depends on more fundamental interactions.

In an interview after his lecture, Sahakian described Verlinde’s argument as “a repackaging of gravity” instead of a complete, original theory.

“We need to be cautious about sensationalizing something that is supposed to be analyzed,” he said. For now, Verlinde’s paper won’t influence the way Sahakian teaches physics.

Sahakian acknowledged, however, that Verlinde’s ideas could have a massive effect on modern physics if widely adopted.

“It would be a major revolution, on the same order as relativity, as quantum mechanics,” Sahakian said.

If what Verlinde says is proven true, Sahakian said in his lecture, then string theory—the idea that the world is made of tiny strings in vibration—could instantly become obsolete.

Physics professor John Townsend, who also teaches at Harvey Mudd, said that string theory owes its current popularity to its success in accounting for all four so-called fundamental forces: electromagnetic, weak, strong and gravitational.

“It’s the only theory that we’ve got that actually unifies quantum mechanics and gravity together,” Townsend said.

“In my view, the reason that they’re unifying these things, trying to do this, is they’re thinking gravity’s really a force and the trouble is that only string theory, with crazy extra dimensions in space and being extremely difficult to test, seems to be a self-consistent quantum theory of gravity,” he added. “But if somebody comes along and says gravity’s not a force, then what’s the point of trying to say ‘I need a quantum theory of gravity’?”

Yet it’s too early to pronounce string theory dead, since few physicists fully accept or even understand Verlinde’s idea of gravity as an entropic force.

“I was struggling to understand [Sahakian’s lecture], and I’m a physicist—and a theoretical physicist at that,” Townsend said, adding that he had tried reading Verlinde’s paper but failed to make sense of it.

Townsend added that one problem with Verlinde’s paper is that it is almost impossible to test through experiment, normally an essential part of scientific research.

“That’s what distinguishes us from mathematics,” he said. “We’re supposedly trying to explain the real world.”

Even Sahakian acknowledged that he finds parts of Verlinde’s argument perplexing.

“I don’t understand it fully,” he said. “I have lots of questions about it.”

Sahakian, who took a sabbatical last year and worked on research at Cal Tech, said he had personally asked Verlinde some questions about the paper but wasn’t satisfied with his answers. For now, Sahakian thinks of Verlinde’s theory as “a curious idea which is still half-baked but worthwhile to talk about.”

Sahakian said he is planning to continue his “physics outreach” with a series of lectures about modern physics that will begin next semester. The lectures, he said, will focus on more thoroughly established concepts and will be open to 5C students as well as the general public.