Big mysteries explained through your senses
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What is the Big Bang and why was it silent?
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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. Fed And NPR. I'm Minush Zamarodi. 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. uh suggest an explosion, it suggests a sound. But 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 pre-existing space, but it it was the 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. Uh started um 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 14 billion year life of the universe, Mark 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 by gravity pulling gas into these slightly denser regions and away from the slightly less dense regions. So you have this whole set of compressions and rarefactions.
This created sound waves moving through the entire young universe. Of course, no one was around to hear them, and even if you somehow could have been there, your ears would have been useless.
The frequencies of the waves that I mean I'm talking about are one at one wave every fifty thousand years, so I mean you wouldn't even live to see one wave pass you.
But what if we translated those waves into something the human ear can perceive? What would the beginning of the universe sound like? What you're about to hear represents the first four hundred thousand years of the universe, compressed into about ten seconds and raised roughly fifty octaves into the range of human hearing.
Thanks to Mark Whittle, it's like we can hear the universe expanding.
So the the most obvious thing
How did scientists turn the universe’s early acoustic waves into audible sound?
Із декреас, та дроп і піч.
Mark says, imagine the young universe as an enormous musical instrument, almost like an organ. At first, only its smallest pipes had enough time to produce waves, but as the universe aged, larger and larger regions joined in, and larger pipes make deeper notes.
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Chapters
4 chapters
1
What is the Big Bang and why was it silent?
0:00–5:00
2
How did scientists turn the universe’s early acoustic waves into audible sound?
5:00–11:01
3
What does the “acoustic era” tell us about the early structure of the cosmos?
11:01–20:39
4
How did Mark Whittle translate cosmic sound waves into music and a choir performance?
20:39–54:22