What's behind a pulse? The second episode dives into the world of an ice climber, a bus driver, a woman in labor, and a senior dance club to show how the human heart and the circulatory system power our physical and emotional lives, and create the pulsing rhythm of our world.

The episode is a journey through the human gut and the process of turning food into energy to keep the body going. Humans have turned eating into culture, a way to celebrate our roots, to bring us together. But food is really just one thing: Fuel. It's where you get the power to live your life. Even when you're sitting completely still, your body needs a lot of energy to stay on. But nowhere is the need for fuel more apparent than when you push yourself to the absolute limit. And the microbiome, the bacteria living in our gut, plays a great role in all this.

A look into how the body defends itself against all odds through the stories of a nature survivalist, rancher twins, a doctor who survived Ebola and a cancer therapy recipient. The Immune System, essential to our survival every second, is the most complex and least understood piece of our biology.

How do the five senses really work? In fact, there are many more than five, and they all work together to create our own version of reality. We dive into the stories of a pairs figure skating team, a perfumer, a cave explorer, and a musician to decipher how different ways of sensing the world all create their own vivid, and unique, picture.
This episode explores the world of human sensation and how it defines reality.

There is a region of space that is dangerous for reasons we don't yet understand completely. We see an increased flux of energetic particles in this area and higher-than-usual levels of radiation. It's called the South Atlantic Anomaly. Some scientists now think the long-term effects of this danger zone may be far wider reaching than anyone ever expected, and it may even have implications for the future of humanity in space and on Earth.

It is a dark, mysterious, and secretive world. A world of clandestine projects, secret rocket launches, and futuristic tech. In December 2019, the United States Space Force became the newest branch of the military. It will defend the vast infrastructure of satellites, currently orbiting largely unprotected above Earth, and be ready to attack if they came under threat. This is also the story of the race to build the ultimate space weapon.