Bill visits a cannabis dispensary in Hollywood and takes a trip through hemp history. Kevin Smith and other panelists weigh weed's pros and cons.

From phishing to malware, Bill uncovers the scams that steal our data. Steve-O talks about the time he exposed himself … to hackers.

In search of better sleep, correspondents seek out NASA scientists and a professional cuddler. Bill busts myths about naps, dreams and turkey.

Bill spreads bad news about antibiotic-resistant gonorrhea and other superbugs. Comedian Ali Wong stops by the studio for a glow-in-the-dark demo.

Bill breaks down the science of time travel with guests Zach Braff, retired astronaut Scott Kelly and the minds behind "Star Trek" and "Lost."

Sex is complex! Bill explores the ever-evolving science of sexuality with help from a panel of experts and "Crazy Ex-Girlfriend" star Rachel Bloom.

Bill and his guests talk about tackling overpopulation by empowering women. Comedian Joanna Hausmann interviews couples about male contraception.

Do dogs get depressed? Do monkeys like magic tricks? Bill and his guests explore animal behavior that's remarkably human

Bill explores advances in IVF that are helping couples have healthy babies. "Project Runway" star Tim Gunn hosts a special fashion show in the lab.

Karlie Kloss tours Japanese farms that grow produce without soil to save water and space. Back in the studio, Margaret Cho samples meat made in a lab.

Bill explains how addiction changes the brain, comedian Maria Bamford shares her struggles, and Cara Santa Maria visits a research lab casino.

In London, mutated mosquitos make a meal of Derek Muller. Comedian Paul F. Tompkins helps Bill burst a common myth about evolution.

Derek Muller discovers why Mexico City is sinking, Nazeem Hussain tests his desert survival skills, and Bill has a drink with a "water sommelier".

As Bill breaks down the science of aging, his correspondents try bizarre beauty treatments and learn how spinach could transform organ transplants.

Chemtrails. Crop circles. Palm readers. Bill takes aim at pseudoscience and explains how confirmation bias makes us believe things that aren't true.

Bill introduces the theory of panspermia, NASA scientists discuss the Mars 2020 mission, and Wil Wheaton and the panel ponder life on other planets.

What's in a calorie? Bill flambés a marshmallow in the name of science, experts weigh in on fad diets, and singing kale keeps it real about nutrition.

Bill extracts DNA from a strawberry in the lab and talks about genetically modified foods with a Monsanto executive, a professor and a farmer.

Bill and his correspondents check out video game technology that's changing the world, including a game that helps surgeons sharpen their skills.

Bill and the panel discuss private space travel. Mean astronaut Joel McHale answers questions, and lunar gravity gives a young basketballer a boost.

From robots that paint Rembrandts to Twitterbots gone rogue, Bill and his guests explore the potential and pitfalls of artificial intelligence.

With help from some friends in raincoats and a room full of unemployed germs, Bill demonstrates how vaccines work and why everyone needs to get them.

Bill and his panel of experts debunk bogus alternative remedies like homeopathy, the healing power of magnets ... and curing cancer by yelling at it.

Bill calls out climate change deniers, breaks down the science of global warming and explains how we can make the planet a cooler place to live.

OK Go and Drew Carey help Bill explain extinction, and the panel reveals how scientists could one day bring extinct species back to life.