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1-7 Beginning of the Universe Look Far into the Past III

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From the Big Bang to Dark Energy

Universidad de Tokio

4.8 (1,531 calificaciones) | 40K estudiantes inscritos

We have learned a lot recently about how the Universe evolved in 13.7 billion years since the Big Bang. More than 80% of matter in the Universe is mysterious Dark Matter, which made stars and galaxies to form. The newly discovered Higgs-boson became frozen into the Universe a trillionth of a second after the Big Bang and brought order to the Universe. Yet we still do not know how ordinary matter (atoms) survived against total annihilation by Anti-Matter. The expansion of the Universe started acceleration about 7 billion years ago and the Universe is being ripped apart. The culprit is Dark Energy, a mysterious energy multiplying in vacuum. I will present evidence behind these startling discoveries and discuss what we may learn in the near future. This course is offered in English.

Revisiones

4.8 (1,531 calificaciones)

5 stars
1,284 ratings
4 stars
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3 stars
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1 star
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LF

Feb 29, 2016

This was an excellent course! It was very interesting, well-explained, and easy to follow (even for someone like me, who isn't necessarily up-to-date on mathematics). Can't recommend enough!

VK

Jan 02, 2017

Maybe the best course I have taken so far. Very interesting subject great professor and perfect distribution of content. Would like to see another course by professor Murayama in the future.

De la lección

From Daily Life to the Big Bang

Understanding the Universe in which we live and how to probe it can begin with simple daily life experiences such as night and day and the four seasons. Starting from these observations, we will take a journey from our local Earth at the present time all the way to the edge of the universe and back to its birth, learning the techniques and findings in modern physics that provide us this understanding.

1-5 Beginning of the Universe Look Far into the Past I13:31

1-6 Beginning of the Universe Look Far into the Past II5:45

1-7 Beginning of the Universe Look Far into the Past III6:41

1-8 Beginning of the Universe Look Far into the Past IV8:54

1-9 Beginning of the Universe Look Far into the Past V10:20

1-10 Cosmic Expansion6:26

Impartido por:

Hitoshi Murayama
MacAdams Professor of Physics, University of California, Berkeley

Transcripción

So if you look farther out, you also

find there are things called clusters of galaxies.

So in this picture, you see many of these

yellow, round objects, so each of them is actually

a galaxy of its own, which may contain, again,

like a hundred billion stars in each one of them.

But you also see that these yellow objects are living together.

Like, hundreds of them. So they are called clusters of galaxies.

And you see many of these clusters if you look, observe the universe.

And, they are pretty common.

And all of them contain these elliptical galaxies, which don't seem

to have a big spiral, as our own Milky Way galaxy does.

So if you keep observing these things, then you find

sometimes, very strange objects, which look very much elongated, like here.

And also there,

and you see another one down here.

And we'll come back to this question, why we see these very elongated objects.

That also has to do with this idea of dark matter.

But before getting there, let us just get a look at the

this movie which shows how might we might actually fly through the universe.

And this is actually based on real data from Project Sloan Digital Sky Survey.

So using telescope you map out where and

how far away a given galaxy is, what kind of shape, what kind of color.

You put that into computer and pretend that you

are flying through this universe based on the observational data.

And of course, you shouldn't try this at

home because we are trying, actually moving about,

flying through the universe at a speed of like a trillion times the speed of light.

You can't possibly do that.

But anyway, what you see here, is that you know this kind of, the ocean of galaxy,

just keep going on and on forever.

No matter how far you go, you pretty much see the same kind of universe anywhere.

And galaxies are indeed clustered, so they come

in sort of a, big families, here and there.

But you know, again if you just keep going, you'll find another cluster.

Another cluster, another local group, and so on, so forth.

So, the Universe

is stretched, you know, way out there, just keep going on and on.

And so, if you actually flatten this into

a two dimensional map, and it looks like this.

So, this map itself is 2 billion light years across.

And each dot in this map is a galaxy.

And the part that is black, it’s not that there aren't any galaxies out there.

We haven't actually managed to even observe that.

The universe is so big, there's so many portions

with the universe, we haven't even observed carefully, yet.

So, the basic picture is, is you know very clear.

The Universe just keeps going nearly uniformly.

So pretty much, Universe is uniform.

It doesn't seem to be any particular place in the Universe.

Clearly, we're not at the center of the universe in any way.

Our place doesn't seem to be any special over any other places.

Universe seems to be totally uniform.

But there are wrinkles. Some parts have more galaxies,

some parts do not.

So more or less uniform, with small wrinkles on top of it.

So that seems to be the way our universe looks like.

And if you're using the big telescope and try to observe as far as you can.

You see many, many galaxies out there, and this

is a famous picture from the Hubble Space Telescope.

And, here's a question to you.

There is a galaxy in this picture that is at

a staggering distance of 13 billion light years away from us.

Do you know which one that is?

So we start zooming in to this

picture, and you're looking for something like this.

little red spec.

All these objects, which seem to have these shapes and colors and so on...

They are actually close to us.

Maybe as close as, I don't know, 7 billion light years from us.

That's close.

That you can even see the shapes of these galaxies.

But far away ones, you don't see even the shape.

And it's so far away, it looks very dark.

In addition, it actually looks rather red. I come back to this question of redness.

So you just keep expanding this picture from

the telescope, you're looking for this red speck.

If you zoom it further up, it looks like this.

So this little red smudge is

the world record of the farthest distant galaxy observed to date, that is

13.3 billion light years away from us.

So, the universe just keeps going, more or less uniformly.

You see these wrinkles.

But the far away galaxies actually look red.

That's one thing I want you to remember.

Now if you do manage to

look even beyond these galaxies, what would you find?

Nothing.

So it turns out that if you go beyond, let's say, 13.5

billion light years away, there are no stars out there you can see.

It's not limited by our technology, not limited by the size

of our telescope, but there simply aren't any stars out there.

So what's going on here is

the following.

Universe began like 13.7, 13.8 billion light sorry.

13.7, 13.8 billion years ago.

And if you look that far away, it takes that many years, the light to reach us.

So you are actually looking, the image of the past.

So if you remember the fact that sun is

eight minute, light minutes away, what we can observe

with our naked eyes what the sun looks like

is a picture of the sun eight minutes ago.

If you look at Andromeda galaxy, we are looking at image

of And, of Andromeda how it was 2 1/2 million years ago.

So if you look 13.5 billion light years away, you're looking at the way universe

was 13.5 billion years ago. That was just a couple of hundred

million years after the beginning of the universe.

So universe didn't have time to even let a star to be born.

No stars existed back then.

That's why we cannot see anything out there.

So that era is called Dark Ages.

The Universe was too young to let a star to be born.

There's nothing we can see out there, and that's the dark ages.

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