Big mysteries explained through your senses

This message comes from Charles Schwab with their original podcast, Choiceology. Choiceology is a show about the psychology and economics behind people's decisions. Download the latest episode and subscribe at schwab.com/podcast. This is the TED Radio Hour. Each week, groundbreaking TED Talks. Our job now is to dream big. Delivered at TED conferences. To bring about the future we want to see. Around the world. Understand who we are. From those talks, we bring you speakers and ideas that will surprise you. You just don't know what you're gonna find. Challenge you. We truly have to ask ourselves, like, why is it noteworthy? And even change you. I literally feel like I'm a different person. Yes. Do you feel that way? Ideas worth spreading. From Ted and NPR. I'm Manoj Zamorodi. Today on the show, how our senses can reveal things about ourselves and the world around us that might otherwise remain invisible, starting with what we can hear. Roughly thirteen point eight billion years ago, the universe began. We call that moment the big bang, except it didn't make a sound. The term big bang does suggest an explosion. It suggests a sound, but things are a little bit more subtle than that. This is Mark Whittle. He's a professor of astronomy at the University of Virginia. And the first thing that Mark wants us to understand is that the big bang wasn't an explosion per se, at least not like in the movies. It was really in a way the the expansion not of something in a preexisting space, but it it was expansion of space itself carrying material with it. And so paradoxically, the big bang was probably in a way silent because it because everything's moving away from everything else. There are no pressure waves. Pressure waves. That's what sound is. Right now, as I speak, tiny molecules are moving through the air. But if there's nothing to move through, no air, gas, or water, then there is no sound. So the universe in its first few moments was silent. But then as it expanded, things changed. In the young universe, you did actually have a gaseous atmosphere pervading everywhere. That was the nature of the young universe. It was hot, but there was a gas. And through the gas, sound waves can move. So the Big Bang itself may have been silent, but almost immediately afterwards, the universe got noisy. The acoustic era started almost immediately, basically, and extended for about four hundred thousand years. Four hundred thousand years might seem like a long time, but compared with the nearly fourteen billion year life of the universe, Marx says it's roughly the equivalent of its first day. And during this period, the acoustic era, certain areas of space had more matter than others. Gravity pulled gas towards those denser regions, compressing it, bouncing it back out, pulling it in again over and over. What you have there is an approximately spherical sound wave being created …