If you can't defeat death, what if you could postpone it, or at least postpone the diseases commonly associated with getting old?

Many people, especially the ultra-wealthy in Silicon Valley, are investing money into companies trying to answer exactly those questions.

Amazon CEO Jeff Bezos and billionaire PayPal co-founder Peter Thiel have both invested in South San Francisco-based Unity Biotechnology, a company whose mission is to "extend human healthspan, the period in one's life unburdened by the disease of aging."

In 2013, Google formed aging research company Calico. Oracle co-founder Larry Ellison has donated hundreds of millions of dollars to aging research, The New Yorker reported.

There are a slew of other companies tackling aging, including BioAge, BioViva, The Longevity Fund, AgeX and the Methuselah Foundation.

"Whenever you meet a fundamental human need, there's a market," said Michael West, a gerontologist and CEO of AgeX Therapeutics. "And in this case, the market for age-related disease and aging is a trillion dollar market."

But people claiming to know what you ought to do to live longer isn't anything new. Historically, as is still the case today, a lot of it just doesn't work. So what's real? And what's just wishful thinking?

Watch the video to find out more.