This article is more than 2 years old.

May 5, 2016 This article is more than 2 years old.

The potential for clean, limitless nuclear-fusion power has led humanity to spend billions of dollars seeking it out, ever since Albert Einstein came up with the theories that make it possible. With the specter of climate change looming, the stakes are ever higher.

This week on Actuality, we meet scientists testing a fusion reactor that’s hotter than the sun—and they say that a full-scale version could be 25 years away.

Then, we take a detour into the strange world of cold fusion, the people who hate it, and the billionaires risking their money in the field because the rewards could be so large.

You can listen to Actuality and subscribe on iTunes, or use this RSS feed to subscribe with your favorite podcast app.

In this episode, we visit the Princeton Plasma Physics Laboratory and talk with staff, including the lab’s director, Stewart Prager, and chief engineer Alfred von Halle, about the power plant they’re piloting. We also speak to MIT’s Peter Hagelstein and Robert Godes of Brillouin Energy.

After you listen to this episode, give us some clues for what you want to see in future episodes. Who else is doing the impossible? Tell us on twitter, or e-mail us.

Actuality is a joint production of Quartz and Marketplace. Every two weeks, we’ll explore the inner workings of the new global economy, combining the best of our economic smarts.