I don't know about you, but space really freaks me out.

In fact, I consider myself to be something of a space idiot.

But one thing that I thought I really did know for sure was that the Big Bang was a thing that happened.

So imagine my surprise when I find out that we actually didn't have any non-theoretical evidence for the Big Bang until the 1960s.

And that's only because two guys accidentally stumbled on this sound.

That is the sound of the birth of the universe.

It's wild.

I know.

I've been really stressed about how I'm going to understand all of this, much less explain it.

And you know what?

Actually, we can do better than this.

Welcome to the Chabot Space & Science Center in Oakland, California Rolling crew.

Take one.

So, Annie, what were you taught the Big Bang is?

I was taught that it just happened in a bang.

Perfect.

Claudia?

Guess I’ll just mic myself.

Oh, can I help?

I just thought somehow from the earth it was a huge, enormous explosion Big Bang, to me something for some reason really got together and then really started spreading apart.

Same!

I know.

I always thought I think I was always taught it as an actual explosion.

Like I always pictured it like a huge bomb going off.

That was the birth of the universe.

But apparently...

The Big Bang, first of all, is a moment in time.

It's a moment where the universe starts making sense to us.

That's perfect.

But before we can truly appreciate this accidental discovery, we got to wind it back.

As long as humans have been around, we've been looking up at the stars and trying to understand what they are.

The way the stars move around the earth, how their positions change depending on the Earth's progress through its orbit.

We could measure and chart those with our naked eye back before light pollution obscured so many stars.

And then we get instruments like this.

Wait, this is so funny.

If sky is clear, opportunity to use the 20 inch telescope will be given.

If cloudy, there will be a lecture.

These telescopes here at Chabot are what we call optical instruments meaning they show us light in the visible spectrum, so light that would be visible to the human eye anyway, it’s just a little bit closer through the eye piece than it is to us in real life.

*music plays* *music plays* *mechanical sound of telescope dome shutter opening* So this telescope's name is Rachel And she is... how old, Gerald?

108 years old.

108 years old!

And she looks great for her age and works perfectly.

Am I correct?

Wow.

And so what can we see with Rachel?

We can see the moon, we can see all kinds of objects in our solar system, all the planets.

We can also look at things like galaxies, star clusters, nebulae, clouds of gas and dust where new stars are forming.

All kinds of interesting things.

So, Rachel and telescopes like her have all kinds of lenses inside this tube that are refracting and reflecting the light to magnify it for our eyes.

And telescopes haven't changed a whole bunch since the very beginning, Since Galileo, they’re still the same basic principle.

Modern, telescopes tend to be computer operated, and they are automatically programmed to go to the correct place in the night sky.

But with old school gals like Rachel, you got to point her in the right direction.

What I just moved was 4,000 lbs.

And it was that easy?!

It’s so well balanced I can move it with one finger.

Majestic.

You can see so many of you in here!

Lenses on lenses, on lenses, on lenses...

When we’re looking at the stars from a certain point in space, whether that's here on Earth or through some kind of instrument on a satellite, it's essentially like looking out at a flat photograph.

It's really hard to tell how far away things are from us in this dimension, like how far away from us is this, for example?

The key is light!

See, most measurements that we are making of space to understand what the heck is going on out in it can be boiled down to measuring different kinds of light, and that's visible and non-visible.

The visible part of the spectrum is all of the light we can see and we measure that with optical instruments like those telescopes we just saw.

But the other stuff, the invisible stuff is all of these other frequencies outside of that.

That's radio, microwave, infrared, ultraviolet, X-ray, gamma, And there's another set of techniques that we can use to measure all kinds of light, both visible and nonvisible, called spectroscopy that tell us so much about the stuff out there in the universe, like what galaxies are made of and exactly how far away from us they are.

And just like what they're up to out there.

The Blowtorch.

Classic.

We’re filming a section about sound and there’s a blowtorch.

one of the main concepts that scientists use to understand what stuff out in space is up to is called the Doppler Effect.

Let's demonstrate.

And actually, Annie, will you come stand here?

I'm going to do something really silly.

AAAAAAHHHHHHHHHHHH As I run around Annie, my voice is picked up by Claudia’s microphone.

and the closer I get to the microphone, the higher my voice sounds, the farther away, the lower my voice sounds.

That’s because of the way the sound waves that are being generated by my voice behave as I move.

the Doppler Effect applies to sound waves, but it also holds true for light.

Now, we know that blue wavelengths of light are shorter and red wavelengths of light are longer, which means that as something moves away from us, it's going to have a red wavelength.

If something is moving towards us, it's going to have a blue wavelength, because of that Doppler Effect.

We call these red shift and blue shift.

It's kind of like red shift, blue shift, one fish, two fish, Say that three times fast.

Now we know from spectroscopic measurements, from astronomical instruments that galaxies in our universe have red shift, which means that they are moving away from us.

And the farther out we go, the more red shift those galaxies have, which means the faster they're moving away from us.

like we have bad breath or something.

But all of this means that the universe has motion and that it's expanding and that it's expanding at an ever increasing rate the farther out we go.

But if that's true, then the question becomes where is it expanding from or more accurately, when.

And here is where we come back to how an annoying noise gave us the key to the birth of our universe.

And I'm not going to go through all of the back and forth that led up to this.

But essentially what you need to know is that it went kind of like this.

OMG.

Okay.

You know, Steady State theory, right?

Duh.

Everyone knows the universe is full of evenly distributed stuff.

And it's always been that way.

And it's totally, always going to be that way forever.

Right?

Except Edwin Hubble has been out measuring galaxies, or something, I guess?

And they're red shifting, which means they're moving away from us.

And not just that, but, like, everything in the universe might be moving away from each other.

But if you work backwards from that, it means that at one point, everything in the universe was really close together, like super, super, super tightly packed.

Do you think Steady State knows?

I don’t know!

I mean, everyone is talking about it, But it's still like, pretty controversial in the field.

And nobody really like that respectable actually supports it - Oh, hold on.

Other line.

Hello?

Okay, so you know how I'm a big supporter of the Big Bang Theory, right?

Well, according to my calculations, if there was a super hot, super dense moment in the universe, there would be some radiation lingering from it out there that we could detect.

So I'm going to go looking for it.

I gotta call you back... Who was that?

That was Robert Dicke, and he thinks that - Wait, wait.

Hold on, other line.

Dude.

We just got access to an old radio antenna and we’re going to use it to scan the sky and look for all kinds of really cool stuff.

Yeah, it’s so exciting!

We're not really looking for anything to do with Big Bang Theory, though...

I mean, I’m a pretty big supporter of Steady State Theory myself, so...

I don’t know!

We’ll see what we find!

Who was that?

Oh my gosh.

So you know how different wavelengths of light can be expressed as heat, right?

I mean, yeah.

Longer wavelengths are cooler.

Shorter wavelengths are hotter... so?

Yeah.

Well, I just got a call from Arno and Robert from Bell Labs up in New York, and they've gotten their hands on a radio antenna that's basically like one of those thermometers you can point to someone forehead to take their temperature, And girl, they're about to point out that the universe’s forehead!

So Arno and Robert have their big thermometer, which was really intended for something else entirely all ready to go.

They turn it on and they hear the noise.

At first they think maybe it's because they're too close to New York City.

But no, that's not it.

So then they think maybe it's because we recently did above-ground nuclear tests and there's lots of radiation left in the atmosphere that the antenna is picking up.

So they wait a year and the noise is still there.

So, no, that's not it.

In desperation, they think maybe it's the pigeons that are roosting inside the antenna, so they get up on a ladder and hand scrub for a whole day, pigeon poop out from inside the antenna, and the noise is still there.

So they have no idea what it is.

But they talk to people who do know what it is and were actually looking for it and they conclude that what they’re hearing is the sound of the universe.

But where did it come from?

And what does it mean?

This is where I start to be radically underqualified to talk about this, so we’re going to talk to someone who actually does this for a living.

So this noise we actually call the Cosmic Microwave Background.

As background would tell you, it's this diffuse, continuous stream of information that is coming cosmic from the cosmos, from our universe, and microwave tells us which wavelength, which frequency to look for it.

And so cosmic microwave background is the first light, the very first photons that are traveling through from the universe and that are still reaching us to this day.

We can still see the very first light of the universe, and they're coming in a continuous stream.

anywhere you are on earth, you look up, you're getting bombarded, inundated by those primordial photons.

This very first light.

That blows my mind so hard!

Detecting the cosmic microwave background meant that now we went from all of these different possibilities to one theory And so that was the proof that, you know, everybody else was wrong.

And there was one way to move forward in exploring the universe.

So where does this idea get introduced that we're looking for the force of pulling or pushing the universe apart?

Well, actually, it's funny because it was another accidental discovery because at the time we were thinking, gravity tends to pull things together.

And so even if the universe keeps on expanding, it's expanding probably at a slower and slower rate because of all the force of gravity.

That was not what was found.

What was found was, well, actually it's expanding, but it's expanding faster and faster.

So the force responsible for that accelerated expansion of the universe we call dark energy, but dark doesn't mean like actually dark in color.

Exactly.

Yeah.

It's more of a reflection of our own understanding of things.

it's an energy.

We know that.

And then we know little about it.

And so we it is dark to us, dark in terms of we're lacking the knowledge about it.

That's - I'm so glad you clarified that, because I, my whole life, thought that that dark energy and dark matter was literally referring to like the black space of space.

And that's why we called it dark, because that's dark.

And I'm going to jump on that to say dark matter also doesn't mean a very, very dark type of matter.

It means we also lack knowledge on its nature And that's really what's driving the research in cosmology at the moment, trying to understand what makes up, by the way, 95% of the universe, those two things make up 95% of the content of the universe, you know, 75% is dark energy.

energy that's pushing things apart.

And 20% about is dark matter that is making this very heavy skeleton just the same way that your skeleton is, you know, I'm looking at you, but I don't see your bones.

I can still kind of imagine how they're sketching, right?

It's just by looking at you.

Well, for us, it's the same thing.

By looking at galaxies, we're able to get a rough sketch of where dark matter is, you know.

We use the 5% that we can perceive to understand the 95% that we wish we understood better.

I've been really lucky to join the dark energy spectroscopic instrument collaboration, and DESI is a multi object spectrograph, meaning instead of measuring, you know, the distance of one galaxy at a time.

So you point and shoot and then you move on and you move on.

We do 5000 at the same time and we do 5000 every 20 minutes, And what we're trying to do is we're trying to build a very large 3D map of the universe.

And then as time evolves, we're looking at how the cosmic web changes with time to understand what dark energy is.

So basically we're looking at galaxies to understand where dark matter is and how the very structures of dark matter are changing is telling us about dark energy.

what's informative for us is to have a very high resolution, but also very large map.

And so an instrument like that really allows us to go for that science goal.

And so that's letting us see the redshift that tells us how far away galaxies are from us here on Earth and therefore how old they are.

You've got it right.

Okay, great.

For the very first time in my life, I feel like I'm actually understanding this, thank you Satya.

Have there been any moments for you where a failure has led to you learning something new?

I would say every day, you know, we get things wrong every day.

Or another way to say it is we're figuring things out every day it's good to get things wrong because then you can get them right rather than stay stuck somewhere.

I think that's actually also a very valuable lesson to learn.

Okay, I feel a little bit less like a space idiot now.

And I really hope you do, too, because it's really comforting to me to know that the experts are kind of just like us, not only discovering things by accident and then just rolling with it, but also looking up at the night sky, asking big questions about the great unknowns of which there are still many when it comes to space.

And hey, if you're interested in science, that is a little bit closer to home here on Planet Earth, then I highly recommend you check out this show that I've been loving on PBS Terra called Hungry Planet.

It's all about the science of the food that's going to take our planet into the future as we keep growing and growing.

Just pro-tip: don't watch it on an empty stomach.

Okay.

Thanks for watching.

See you on the next one.

I hope that you also feel -