Some Silicon Valley billionaires are looking for it – or at least a way to extend life spans dramatically, perhaps by hundreds of years.

One scientist sponsored a $1 million contest – the Palo Alto Longevity Prize – for researchers who can stop aging. Alphabet Inc’s Google has a business called Calico, also focused on extending life spans. Entrepreneur Peter Thiel, a cofounder of PayPal Holdings Inc, has funded anti-aging research and has even declared himself against death. “Basically, I’m against it,” he told a British journalist a few years ago.