By day, Mark Suppes is a web developer for fashion giant Gucci. By night, he cycles to a New York warehouse and tinkers with his own nuclear fusion reactor.
The warehouse is a non-descript building on a tree-lined Brooklyn street, across the road from blocks of apartments, with a grocery store on one corner. But in reality, it is a lab.
In a hired workshop on the third floor, a high-pitched buzz emanates from a corner dotted with metal scraps and ominous-looking machinery, as Mr Suppes fires up his device and searches for the answer to a question that has eluded some of the finest scientific minds on the planet.
Mr Suppes, 32, is part of a growing community of "fusioneers" — amateur science junkies who are building homemade fusion reactors, for fun and with an eye to being part of the solution to that problem.
He is the 38th independent amateur physicist in the world to achieve nuclear fusion from a homemade reactor, according to community site Fusor.net. Others on the list include a 15-year-old from Michigan and a doctoral student in Ohio.