Mr. Lanier said he had declined any funding from Mr. Epstein and that he had met with him only once after Mr. Epstein in 2008 pleaded guilty to charges of soliciting prostitution from a minor.

Mr. Epstein was willing to finance research that others viewed as bizarre. He told one scientist that he was bankrolling efforts to identify a mysterious particle that might trigger the feeling that someone is watching you.

At one session at Harvard, Mr. Epstein criticized efforts to reduce starvation and provide health care to the poor because doing so increased the risk of overpopulation, said Mr. Pinker, who was there. Mr. Pinker said he had rebutted the argument, citing research showing that high rates of infant mortality simply caused people to have more children. Mr. Epstein seemed annoyed, and a Harvard colleague later told Mr. Pinker that he had been “voted off the island” and was no longer welcome at Mr. Epstein’s gatherings.

Then there was Mr. Epstein’s interest in eugenics.

On multiple occasions starting in the early 2000s, Mr. Epstein told scientists and businessmen about his ambitions to use his New Mexico ranch as a base where women would be inseminated with his sperm and would give birth to his babies, according to two award-winning scientists and an adviser to large companies and wealthy individuals, all of whom Mr. Epstein told about it.

It was not a secret. The adviser, for example, said he was told about the plans not only by Mr. Epstein, at a gathering at his Manhattan townhouse, but also by at least one prominent member of the business community. One of the scientists said Mr. Epstein divulged his idea in 2001 at a dinner at the same townhouse; the other recalled Mr. Epstein discussing it with him at a 2006 conference that he hosted in St. Thomas in the Virgin Islands.

The idea struck all three as far-fetched and disturbing. There is no indication that it would have been against the law.