For a sample of what this course will include, see the video "Energy, Environment, and Everyday Life MOOC with University of Illinois Professor David Ruzic" - http://go.citl.illinois.edu/Energy-MOOC This course teaches you everything you need to know about energy, the environment, and at least a number of things in everyday life. It starts by talking about energy itself and where it comes from. This includes how much we have, who has it, who uses it, and what that all means. The video clips are produced in a fast-paced multimedia format during which Professor Ruzic throws in fun and demonstrations. There are multiple-choice questions to check your understanding and some more in-depth exercises to guide you deeper into the subject. After explaining the main things we use energy for – our cars and electronics! – fossil fuels are examined in detail. Want to really learn about fracking or pipelines? Watch these segments. The environmental effects of fossil fuels are taught as well. Global warming, acid rain, and geoengineering all are in this part of the course. Part of their solution is too. Renewables follow, with clips on solar, wind, hydro, geothermal, biofuels, etc. You’ll even see Professor Ruzic in a corn field and in the middle of a stream showing how you could dam it up. Finally, nuclear power is taught in detail – how it really works and what happens when it doesn’t work, as in Three Mile Island, Chernobyl, and Fukushima, as well as how we are making it today, which is shown here without political preconceptions. In this course, economics takes center stage. People will ultimately do whatever costs the least, so energy policy is most effective when it is targeted at the user’s wallet. Throughout the course there are 24 segments on “How Things Work." These guides to everyday life are tremendously varied, covering everything from fireworks to making beer to what happens backstage at a theater. The course is designed to be enjoyable as well as informative. We hope you will take a look!
How Things Work: Gateway to the Heavens
Loading...
En provenance du cours de University of Illinois at Urbana-Champaign
Energy, Environment, and Everyday Life
19 notes
À partir de la leçon
Week 4: Oil and Gas – With Us Forever?
Oil and natural gas are the most used and most popular energy sources in the world. What are they? Where do they come from? Who uses, needs, and makes them? All the facts and the controversies over pipelines and hydraulic fracturing (fracking) are discussed in detail. All of this is tightly tied to economics so grab your wallets – you will really see where your money goes! "How Things Work” takes us to high places – an observatory, a cell phone tower, and a laser light show!
Rencontrer les enseignants
David N. RuzicAbel Bliss Professor
Nuclear, Plasma and Radiological Engineering
[SOUND]
Well, I'm here with Jim Kaler, Professor Emeritus of Astronomy, and many times,
I've had the pleasure of talking to this gentleman and
showing classes this wonderful institution.
>> It's a great place.
This is really just one of the neatest buildings on the campus, I think, and
one of the oldest.
>> Yeah, how old?
>> They put this up in 1896, I think it was completed in October of 96.
>> 96.
>> So it's, quick, you can do the math, I'm not good at it.
But it's old, and it looks it too.
We're trying to get it [CROSSTALK] restored, yep.
It was built for
the grand sum of $15,000 by special appropriations of the state legislature.
>> Okay, and I would imagine that adjusting for
inflation, that's definitely [CROSSTALK] >> It'd be several million
to put this thing up right now, with the telescope as it is.
It's a beautiful old instrument, handmade by Brashear,
a Pennsylvania optician in the 19th century.
>> Wow.
>> A beautiful piece of work.
>> And then it was, I'm sure, really far from the rest of the city and
[CROSSTALK] >> This was built, you won't believe it,
this was built on the hill.
>> On the hill.
>> Yep.
>> On the hill.
>> If you walk up,
you actually are walking up from the union up to this building.
And at this time, the moral plots,
the corn plots, I hear are about six times the size they are now.
And it was dark, and there are no lights.
>> Yeah.
>> Speaking of, this was isolated.
So it was just a lovely place for an observatory.
>> Probably show an aerial shot here.
But you can see now that that's really surrounded completely by campus.
>> Yeah, yeah, yeah, [CROSSTALK] I mean,
the lights are bright enough to melt you when you walk outside here.
>> [LAUGH] >> We've tried over the years
to keep it down.
Some of the lights are shielded.
And then we had promises that they would be further shielded, but never.
>> Never have.
>> And it probably wouldn't make much difference at this point anyway.
But we can still see a lot of bright things on it,
we can still show students the moon, which is a knockout scientist telescope.
I don't care how bright it is,
you can see the moon downtown New York City without any trouble.
But the bright planets, Jupiter, Saturn, Mars,
when it's available, it's a stunning sight.
You wouldn't believe what people say when they see Saturn through this for
the first time.
They don't believe that they're actually looking at it.
>> That's real, that's [CROSSTALK] >> You have a slide up there.
No, it's really Saturn, it's a beautiful thing.
>> Yeah.
>> And you can see some bright double stars and
clusters, so it's still quite useful.
And enough so that we've had it restored the last couple of years and
put back to its pretty much original condition.
>> And of course, a great educational experience.
>> It is, and we've got a spectrograph attached to this.
There's a fiber optic system that runs into a room over here,
where we can do bright star spectroscopy.
So it's a fine educational tool.
It was a research instrument in the early years.
The last research was done on this telescope in the 1980s, believe it or not.
But we're testing photometers and actually making some measurements.
And the students resuscitated the old telegraph system up there and
actually made some asteroid measurements in the 1980s.
And but it's principally known for
the development of electronic astronomy around 1912 or so,
where light signal can be converted into an electrical signal.
And you can make a direct measurement of the brightness of a star or
anything else that you were looking at.
>> Wow, and it happened right here.
>> It ultimately revolutionized astronomy, and
it happened right here in this building.
[CROSSTALK] Which is why we are a national historic landmark,
not just a historic place, registered historic place on the outside.
It is a national historic landmark, which is the highest honor that
the Interior Department can give to a building or an organization.
That was given in 1989.
The observatory was made famous by Joel Stebbins,
who was the person who developed the first photometer.
And there is what we call a light curve, the brightness of a variable star
against time, in the Astrophysical Journal for around 1915 made
with this telescope, which is as good as anything you can get today.
A bit of an exaggeration, but
it's just beautiful work that was done with this instrument.
>> Now this pillar here, this sounds very important [CROSSTALK].
>> This is the pier, the pier for the 12 inch, which is up there.
The 12-inch telescope is mounted on a large base,
which we'll see when we go upstairs.
On this pier, and the pier goes down through the floor into the basement.
We've got to get into the basement here, it's really interesting.
And then you see the pier continues down, and then it continues down into the dirt
to, I suppose, some sort of solid layer underneath,
wherever that would be in Illinois, as far as you can go.
So the telescope is not a part of the building.
The building is built around the telescope, and you can jump up and
down like this and the telescope will shake and shimmer.
That's right, they're all built like this, all telescopes are built like this,
unless they've been used strictly for amateur work or for educational work.
But if you were going to have a research instrument.
But all telescopes are built this way.
The building is built around the telescope.
You don't want vibrations transferred to the telescope [CROSSTALK]
>> If someone randomly walks through the
door, you don't want them to screw up the measurements you've been doing all night.
>> Right.
>> Hey well, let's go upstairs and take a look.
>> Yeah, let's go upstairs.
You notice that the shutter is facing east.
You go anywhere in the world, and you will see telescope shutters,
which now let me say this as clearly as I can.
You notice that the telescope does not stick through the shutter.
>> Yes, yes, very important.
>> As you will see in cartoons everywhere, it does not.
The purpose of the dome in the shutter, of course, is to shield you from the weather.
And you have a narrow slit through which you see things.
And you can rotate,
you can rotate the thing around if I can find the little handle.
>> And this chair is fun too because you need to look through the eyepiece, and
sometimes the eyepiece is up here.
So you can sit in the chair,
and the chair moves around the room, so you can get height.
>> And of course, the dome rotates around.
I don't want to do too much of that because it's going to need some more,
it's a little delicate system, but it works fine.
And you notice always telescope shutters face east.
You go to a major observatory, you got a dozen observatories,
they're all facing east, why?
>> Well I used to think [CROSSTALK] >> I love asking students this question.
It is not a religious thing.
>> That's right, and it's not, I don't think, a prevailing weather-
>> Yes, it is.
>> It is?
>> Yeah, on the average the winds are coming from the west and the southwest.
>> I see, except for here?
>> They rarely come directly from the east, so in the US at least,
you almost always position telescopes to the east, and it's become a tradition.
>> Sure.
>> Even, no matter what, you just do it, face east.
There's a cat walk out here, in which you used to be able to bring students.
We don't do that anymore for liability reasons.
It's kind of delicate.
Yes, this is the original observing chair from the 19th century.
The telescope points to all parts of the sky, and
you can- >> Adjust the height.
>> Adjust the height of your seat to the- >> And then the [CROSSTALK]
>> Eye view, kids, I'll tell you,
grade school kids love this.
>> I'm sure. >> Never mind the telescope,
they want to ride on the chair.
It's not like it's a thrill ride, but it's fun.
>> And you actually looked [CROSSTALK] >> We still have a little bit of work
to do here.
We've gotta get a new rack and pinion, that is partly stripped in there.
>> And these other two are just for the [CROSSTALK]
>> This is a finder telescope.
It is a low power finder telescope, it's used to find your field.
You center your object in this thing, it'll be in the center of this thing.
But it's kind of hard at high power.
This is very low power.
If you get something high power with this, it can be hard to find.
Here are your settings, this tells you where north and
south of the celestial equator the star or whatever you're looking at planet is.
And the other settings circle over here tells you how far east and west.
This thing is fairly fixed.
This one over here of course changes as the sky rotates or as the Earth rotates.
And you then use a Cnidaria clock
to calculate what the position should be east or west of the celestial meridian.
It can be done automatically now in big telescopes.
>> Yep.
>> We don't even think about it anymore.
But here you would actually have to do a in the head calculation [CROSSTALK]
>> Calculation to find out
where you're at.
>> And you can look through here in the finder,
then it's here in the main telescope.
Now these other little telescopes are for
verniers that find setting circles for north and south, east and west.
I think only the north, south one actually works anymore.
There are little microscopes in a sense to see very fine setting circles up by
the top of the telescope that you can't see from the ground.
>> Wow.
>> You can actually set this telescope to a minimum arc if you are very careful.
You can set it quite precisely.
>> Excellent. >> It's a beautiful instrument.
This whole peer structure was taken out and shipped to Pennsylvania for
restoration a couple years ago.
It's fun to watch when they opened the shutter,
brought in a crane from the O&M or whatever they are these days.
And dropped the crane in here and pick it up through the shutter.
>> Really. >> We had a hundred people standing around
watching it, it was spectacular.
>> Wow. And that was for cleaning?
>> It was amazing, the fingertip control the crane operator had.
She could move it a millimeter this way, a millimeter that way, amazing.
>> No, I think I have the same crane operator bringing my fusion device into
the building.
It was also pretty impressive.
>> Yeah, they're quite amazing people.
>> Yeah, good.
>> So that's the story up here.
>> All right, let's take a quick look downstairs.
>> This is the pier that goes about ten, 15 feet down, yeah.
We tell students this is where we throw the ones that fail the course.
>> Right.
>> Yeah, it's a pretty [LAUGH].
>> It's kind of neat when the building doesn't actually touch the pillar.
>> And there's a old machine shop over here.
At least there used to be a machine shop.
To build instrumentation in here and here,
I'm not sure what it is being used for anymore.
That use to be a dark room over here and then there grad and
registered offices under the old new wing which is over here.
Now this little baby [SOUND] in the 70s I think it was,
NASA was circulating moon rocks among to academic departments.
And they require that they be put in a safe overnight.
>> You got yourself a safe.
>> We found this on the campus and brought it down those stairs over to here.
>> Wow!
>> I don't know how big this thing is but I, it's huge.
How they got it in here, I don't know how.
They will never get it back out.
>> Yeah, at least they were going downhill.
>> A lot of torque.
>> So is it still going to be opened?
>> I don't think so.
You need a safe cracker in here to open it.
For a long time it was used for lunch.
>> [LAUGH] >> And
it's now just a kind of a weird thing to see in the basement of the [CROSSTALK].
>> Yeah, no moon rocks any more.
>> No moon rocks any more.
They took those back after we showed them to the students.
So here you are, there's your tour.
>> Great, thank you very much.
>> You're very welcome.
>> You know that big telescope we just saw that's here at the U
of I campus what's inside of it?
That telescope is known as a refractor because the light goes through lenses.
They have the very large lens here at the beginning.
And this large lens is important because the wider the telescope is
the larger the aperture, the more light it can collect.
So clearly you'd like a really wide tube.
But if you want high magnification,
you also need a large distance between the two lenses.
In the lens and the eye piece.
And the longer that distance is, the better the magnification you can get.
So how does the light actually travel?
Well, out on the side we have the image that we want to try to see.
Light comes from that image.
If it's a star it's generating its own light.
If it's something else the light's reflecting off of it.
But that's the light we want to capture.
So, the light comes through and
the first lens bends those rays together into a focal point.
But you notice that you're not looking right at the focal point because
the image would be too small.
You then let those light rays rediverge into your eye piece lens, your objective.
And then this lens takes those light rays and makes them parallel again.
And it makes them parallel,
such that if you projected them back the image is much, much larger.
And that's the principle of the telescope.
Not everyone has enough room to have a telescope that's many meters tall.
Well, here I am with my reflector.
This is a telescope that's quite as powerful as many of the really long ones.
But it works because it actually has the light go back and
forth a few times through the mirror.
So it can end up being shorter.
The real key however is its width
because that ultimately tells you the amount of light that it collects.
And from here through the various eye pieces we can see the stars.
Of course stars are pretty boring to see because
even with a telescope they're still just a point of light.
But the planets on the other hand change from a point of light to an actual disc.
So, you can see the planets.
And one of the coolest things and one of the very first things that Galileo saw
when they made the first telescopes was you can see the moons of Jupiter.
You see tiny little white specks of dots
in a straight line going across the planet actually quite far out from the planet.
That is quite possible to see with a telescope like this.
But the best thing to see is the moon, because when we look at the moon
we see some features maybe we see some dark and like areas.
When you look at the moon through here you can see the mountains and the craters and
its really quite exciting.
So, the kind of small telescope I have is known as a reflector.
It doesn't use lenses, it uses mirrors.
Once again, you want a large opening because you want collect more light.
That light comes through and
you might notice right in the middle there's an obscuration.
You're not going to get any light from this middle spot because there's
a mirror in the way.
The light comes in it is again focused together.
Those parallel light rays are now coming in together,
they come through to another mirror.
That mirror comes back and once again goes through eye piece type objective.
This is the focal length beyond that with the eye piece.
Which allows you to actually once again see the image become much,
much larger then the image that was actually captured.
That’s a reflector telescope.
If you want to see things like this though which is a visible light image.
You're not going to be able to do it with your eye.
And that's because there's not enough photons
to register all of these beautiful colors.
You're need to do this with something that is like a camera,
a digital camera, film or Some type of sensitive CCD array.
So, it can collect the light for a long period of time.
So, to see something like this, or even more impressive, to see something
where there's a variety of different colors, you gotta do something else.
Not just have a long exposure time.
But you have to worry about the Earth rotating.
So, here's a movie of the sky at night.
And as you might imagine, the stars aren't really rotating overhead.
They're staying still.
The Earth's rotating.
After all, we're eventually going to rotate around so
that you can see the sun again.
That's morning.
In this rotation pattern, if I'm focusing in on one object,
this beautiful nebula in the sky, it's going to blur and move across the screen.
So, telescopes need to have a mechanism that allows them to move to compensate for
the fact that the thing they're sitting on, the Earth, is moving.
And that type of clockwork, that type of mechanical conveyance,
is an extremely important part of telescopes to be able to
actually see these beautiful images over a time lapsed period.
The other thing one needs to realize is that we have an atmosphere above
the planet.
If we were down here in gamma rays, x-rays, ultraviolet, a lot of that,
if it got through our atmosphere could harm us, especially the UV light.
This is where our eyes work.
This is the visible light spectrum.
And notice there's a few other holes here and there.
And then, finally, some really large gaps in the ability of the atmosphere to
block signals and the radio waves, which kind of makes sense,
because we use radio waves all over the place.
And it's because they don't get blocked by the air.
If you want to observe things up in the sky, you can use visible light
telescopes from the Earth or this large radio telescope array.
But it isn't just that the Earth's sky, the atmosphere,
blocks certain wavelengths, even those wavelengths that come through,
maybe not so much the radio waves, but the visible light will get
distorted by the differences in density in the atmosphere.
This is what makes stars twinkle.
And here's a beautiful illustration movie of it that I'm not convinced is real
because I don't ever see stars twinkle that much but you get the concept.
That variation in brightness is not due to the star varying in brightness,
but it's due to currents in the air and atmosphere, and
diffraction of different densities of the air coming through.
So if you really want to see what's out there in the cosmos,
And you want to see what comes out in this wavelength period, or
this wavelength period, or this wavelength period, you need to get above
the atmosphere where you have no twinkle, and you have no blockage from our air.
And then you could see amazingly
different stuff when you look at the stars or the nebulas.
You can see what they look like in radio waves, or in infrared,
in visible, ultraviolet, low energy x-rays, high energy x-rays.
And you put this whole picture together and astronomers and astrophysicists get
a much deeper understanding of what actually happens out there in stars.
One way this has been achieved is with the Hubble telescope.
This is a large visible light telescope.
But it's up above our atmosphere.
It's a satellite.
And this is a marvelous tool because it's allowed humans to
still see in the visible but not have that interference and
that shuddering, that twinkling, from the Earth.
Many observatories are on top of mountains and that helps.
But if you get completely above the Earth, it really helps.
And then something like the Hubble, when you use computer control to make sure,
even though the Earth is moving, and it's moving,
that it's always focused in one area, you can see amazing things.
You've probably often been told that when you look up in the sky,
those aren't all stars.
Many of those are galaxies, entire Milky Way galaxies like ours fire away.
That them themselves having millions and millions of stars.
Here's a wondrous picture that shows that's really true.
Looking at one image, and you can see, obviously, some stars.
But look at these ovals and shapes.
These are all galaxies that are far, far away.
You'd never be able to see this on the Earth unless you had a telescope,
like the Hubble, up in the sky.
That's what you need to know about telescopes and observatories,
and the wondrous things we've been able to learn by simply looking up.
[MUSIC]
Explorer notre catalogue
Rejoignez-nous gratuitement et obtenez des recommendations, des mises à jour et des offres personnalisées.
Coursera propose un accès universel à la meilleure formation au monde,
en partenariat avec des universités et des organisations du plus haut niveau, pour proposer des cours en ligne.
© 2018 Coursera Inc. Tous droits réservés.
