It’s time for the next Brains On debate! This intense matchup brings us to the depths of darkness, under the water and beyond our earth’s atmosphere. Who will prevail?

Hosts Molly and Gabriella are locked out. No worries: Sanden and Bob to the rescue. While the duo drives a spare set of keys to our beloved hosts, they pass the time discussing science you might see (or feel) in a car.

On the fourth leg of our road trip, we figure out where traffic comes from and what it would take to make it finally go away.

At the third stop on our road trip series, we coast in for a pit stop and check out car design. We find out how monster trucks are different than cars, how culture influences car design and what it’s like to make car into animated, talking movie stars.

Our planet needs some carbon dioxide, but cars are pumping more into the atmosphere than our carbon cycle can handle. We’ll explore what all this carbon means for our planet. And we talk to a scientist who is working to change how we fuel our cars, so we can cut back on all this carbon dioxide.

On the first leg of our road trip, we’re exploring the history of engines and how they work, with a little help from Car Talk’s Ray Magliozzi.

There are a whopping 10 sounds for you to guess in this episode. Are your ears up to the challenge?

What happens in your brain when you read? What goes into the writing of the words? And what about the making of the books themselves, the physical objects?