One guest spent the day contemplating quantum gravity. Another recalled walking Albert Einstein to chapel at Princeton in 1933, when he was an 18-year-old freshman.

There were plenty of brushes with intellectual greatness at the Institute for Advanced Study’s gala Thursday night at Pier 60 in Manhattan.

And then there was the Jim Simons and David Rubenstein show, in which the billionaires -- a mathematician turned hedge fund founder and a private equity titan -- entertained over dinner for an audience that included Eric Schmidt, Byron Wien, Jeff Koons, and Vartan Gregorian.

The event raised $3.5 million for the scholars haven in Princeton, New Jersey, that took in Einstein after he fled Nazi Germany and counts theoretical physicist Edward Witten -- the guy working on quantum gravity -- as a faculty member.

Why doesn’t Simons wear socks, and was this habit modeled after Einstein?

“It was only tonight that I learned Einstein didn’t wear socks,” said Simons, chairman of Renaissance Technologies. “I don’t wear socks because they take time to put on.”

Rubenstein, who has a show on Bloomberg Television, asked Simons how he rationalizes his smoking habit -- after giving him a crystal ash tray. Simons got a cigarette from the pack of Merits in his jacket pocket and took a fake drag.

“Some people do say that it’s not healthy, but I’m almost 81,” Simons said. “I smoked for 66 years. I think it’s not going to hurt me.”

And there was an even more personal question about the SATs.

“As I recall, I got a 750 in math, and a 750 in the other one,” Simons said.

“Why not 800?” Rubenstein asked.

“I was careless,” Simons said.

He said he’d applied to the Massachusetts Institute of Technology, the University of Chicago and Wesleyan -- and was rejected by Wesleyan. (He went to MIT.)

College admissions were a conversational topic throughout the evening, as guests riffed on the recent scandal.

“Bribing should be standardized to even the playing field,” art dealer Larry Gagosian said. “I’m being facetious, obviously, but it’s not totally surprising. I get so many calls from friends wanting to know if I know someone on the board of this or that school. I went to UCLA. It was a simpler world then.”

No one came to the event to write a check so their kid could get admitted, Two Sigma’s John Overdeck said. The institute doesn’t grant degrees, but rather provides a place for postdoctoral researchers to work independently.

Jim Tisch said he long ago had the idea that the College Board, which administers the SATs, should hold sessions for students to write their college essays, to ensure they write them themselves.

Charles Simonyi, the institute’s chairman, said he has two daughters in elementary school.

“I am considering already the issues of where and how they should go to college,” Simonyi said. “I’m spending a lot of time with the girls. We’re doing Singapore Math.”

As for the institute, it gives him peace of mind on matters of the universe: “I know when the big questions come, we have somewhere to go for answers,” Simonyi said.

Simons received the IAS Bamberger Medal, named for the department store family that provided the money to found the institute, with Simonyi and institute Director Robbert Dijkgraaf outlining some of the reasons he was selected for the award: his work on Riemannian manifolds, IAS board service and contributions to its endowment, his commitment to basic science through the Simons Foundation -- and the fact he’s that rare institute member who became a wealthy patron.

“Jim is as far from the stereotype of the absent-minded professor as one can get,” Simonyi said during the presentation.

Simons said it was his idea for the institute to hold a gala. His inspiration was the Cold Spring Harbor Laboratory Double Helix Medals Dinner, named for the laboratory’s James Watson, which is what led the institute to call its event the Einstein Gala, and to hold it on what would have been the physicist’s 140th birthday.

The first Double Helix medalist was Muhammad Ali.

“Can you imagine a better person to have as honoree,” Simons said. “They got an enormous crowd, but he’s not alive now, so we couldn’t have him. So I was second choice.”