Summer Conference 1999: Science, Ethics & Human Destiny

Contemporary Astronomy: Where are we in time and space

JOHN PERCY, Department of Astronomy, University of Toronto

I want to begin with some truth in advertising. Various versions of the program have advertised this as a talk on cosmology.

I am not a cosmologist. I am an astronomer. If cosmologists are the psychiatrists of the universe, then astronomers are the ordinary GPs. And that’s my role tonight. I want to take you on a space voyage.

Virtually everything I tell you tonight was unknown 100 years ago. So, we have made tremendous progress in 100 years. I expect we will make even more progress in the next 100 years.

Whatever I say and however much I bore you, I don’t want you to lose the awe factor. I don’t want you to lose the capacity to go out any night to look at the night sky, to look into the universe and to be awed by it; not necessarily overwhelmed, but certainly moved by it.

The task I was set with tonight was to tell you where we are in time and space.

The answer is simple.

We’re on this small planet [Earth], 13,000 kilometers across. We’re in the middle of nowhere. We’re 10 billion years from our cosmic birth. We’re heading into a future which is very uncertain.

We share this small planet with six billion other human beings, with countless members of millions of other species; numbers that, incidentally, are changing on a human time scale, not an astronomical time scale.

If you look at a picture of Earth taken during the day from space, you’ll notice that we can’t see any signs of life at all.

But, if it’s a picture taken at nightfall we get a rather interesting view. We see all of this useless light shining up from the major cities of North America, shining up into the sky, wasting energy – in the case of Toronto $10 million a year – and washing out the night sky, clouding our view of the universe.

This is what astronomers call light pollution. We obviously don’t like it and neither should you.

However, not far from here the provincial government has decided to develop a dark sky reserve; a place where people can go to enjoy the dark skies. It’s at Torrance Barrens, just north of Toronto.

If we look at the sky at night, what can we see?

We can all see the Moon. Even in downtown Toronto you can see the Moon.

Let me give you a sense of scale. The Moon is somewhat smaller than the Earth. If you represented the Earth by your head, then your fist would represent the Moon – but you would have to put it eight meters [25 feet] away.

This always surprises people. People think that the Moon is relatively close to the Earth but, in fact, it’s rather far away, which explains why it’s taken so long for humans to be able to go there.

One other interesting fact.

It turns out that despite our educational system and our high tech society, few people really understand things like Moon phases, seasons, day and night. All of those basic things you associate with astronomy.

For instance, 90 per cent of a sample of Harvard graduates cannot understand the cause of the seasons.

As you may know, the features of the "Man in the Moon" are really vast lava plains that solidified three billion years ago, filling in ancient basins with lava.

Looking at a photograph of these basins, we see impact craters. Fortunately, these impact craters occurred on the Moon and not on the Earth.

But all this time impacts have been occurring on the Earth, as well. We have a particularly large number of them in Canada.

It was just over 30 years ago when the first humans set foot on the Moon.

If you look at a picture of the first man on the Moon photographing the second man on the Moon, you’ll notice in the background that the sky is black. That is because there’s no atmosphere on the Moon.

There are, however, cars. There’s cars everywhere, of course. So the astronauts drove around in their cars. They left a few footprints and garbage behind and then they left. Basically, nobody’s gone back there for 25 years.

It’s rather sobering to think that this garbage that was left on the Moon will last much longer than our civilization here on the Earth.

Let’s continue our space voyage by visiting the Sun.

The Sun is much larger than the Earth. The Sun makes up 99.8 per cent of all the mass of the solar system, which means that its gravity binds us all together. Its energy supplies all the energy for life and has done so for five billion years.

Let me give you a little bit of physics here.

The Sun is a remarkable thermonuclear reactor. The Sun has been generating four hundred million million million million [correct] watts of energy for about five billion years and will continue to do so for five billion more.

The Sun has discovered this almost inexhaustible source of energy, which is called thermonuclear fusion. You simply take hydrogen, you convert it into helium and watch the energy flow out.

If we could harness this on the Earth we would solve many of our energy problems.

Let’s continue our voyage and look at some of the worlds that were simply dots in the sky a hundred years ago.

If you examine a photo of the planet Mercury, you find it looks suspiciously like the Moon. The reason is that Mercury and the Moon are virtually the same in size. They have no air, no water, and they’ve retained impact craters over billions of years.

In fact, the circles seen on the surface in photographs of Mercury were formed in the first half billion years of the solar system’s history, when things were really chaotic – not only on Mercury, but on all of the other planets, including Earth.

Move further out in space and you find Venus, which is rather different.

The Soviet spacecraft, Venera, managed to survive on Venus for about an hour before it was crushed by an atmosphere 100 times denser than the Earth’s atmosphere, with a temperature that’s hotter than Hell.

Incidentally, you can calculate the temperature of Hell from Scriptural references. It works out to be about 600 degrees.

Venus is still active geologically and is interesting because, with one exception, all the features on Venus are named after women.

Moving further out in space on our journey and skipping by the Earth, we get to the next planet, Mars.

Mars has excited people for many years. A hundred years ago the thinking was that Mars could be inhabited. It all goes back to an optical illusion that was seen first by Italian astronomers. They saw what they thought were narrow channels on Mars and the Italian word for channels sounds like the English word canals.

And from that, the whole story of the canals on Mars developed. They’re strictly an optical illusion. There are no canals on Mars.

Mars has reddish-coloured deserts and polar caps that are mostly carbon dioxide ice, rather than water ice.

Mars was interesting to writers and prompted writers, such as H.G. Wells and Edgar Rice Burroughs, to launch the beginnings of science fiction and has led to such programs as the X-Files and all of that sort of stuff.

As astronomers sent spacecraft to Mars, it became less interesting in some ways and more interesting in others.

There were no canals. Yet, there was an environment that was tremendously exciting to people like me who had read some science fiction.

If you examine a photo of the surface of Mars, you will see reddish rocks. And you’ll notice the sky is not black, because there is a thin atmosphere.

Mars right now is pretty cold and dry.

But the images produced by spacecraft missions have produced exciting evidence of flood plains and river beds and evidence that early in its history Mars was much warmer, much more hospitable to life.

The possibility arises that life might have existed on Mars early in its history. That’s one of the motivations for a number of spacecraft missions going to Mars in the next decade or so.

I should mention, as we move onward on our space voyage, that each planet in the solar system is about 1.7 times further from the Sun than the next one in.

So, if you go 1.7 times the distance from Mars there should be a planet there. And there isn’t. We discover there’s just a whole bunch of chunks of material that we call asteroids.

A typical asteroid is about 15 kilometers by 10 kilometers. It’s roughly the size of Toronto and rather irregular. Although there are much larger asteroids, the largest is still only a few hundred kilometers in size. Most of them are small.

Most, in fact, are so small that we don’t know they’re there. And that’s another story, because they might be heading in our direction.

Back in 1977, when the University of Toronto celebrated its 150th birthday my colleagues in the astronomy department decided to go out and discover an asteroid .

If you discover an asteroid, you can name it after anything you want. The one they discovered we named Toronto. And being politically astute, we presented it to both the university and to the City of Toronto.

So, somewhere out there in the asteroid belt there’s a piece of useless real estate that has Toronto’s name on it. Luckily, its orbit is not likely to carry it anywhere near the real Toronto.

The reason that the asteroids are there is not because there was a planet that exploded, which is a popular myth, but because there was a planet that never formed. The culprit on all of this is the giant of the solar system, namely Jupiter.

Jupiter is 1,000 times bigger in volume than the Earth; 300 times bigger in mass.

Next to the Sun, it’s by far the biggest thing in the solar system and its gravity is quite disruptive. We believe that’s why a planet never formed in between Mars and Jupiter.

Jupiter also has a wonderful collection of satellites. The two most interesting ones are Io and Europa, two of the four so-called Galilean satellites of Jupiter, because Galileo discovered them with his first telescope.

Io is interesting because it’s the most-intensely volcanic object in the solar system. There are constantly volcanoes erupting on this satellite.

Europa is even more interesting.

Europa has a thick crust that appears to be made primarily of ice. High resolution pictures taken by the Galileo spacecraft show what seem to be blocks of ice that are imbedded in some kind of glacial crust. There is evidence that beneath the icy crust of Europa there is a layer of liquid water and water is considered to be a necessity for the origin and development of life.

Another exciting mission within the solar system right now is to develop ways of exploring Europa to see whether in the subterranean oceans, if they exist, there is any evidence that life might have developed.

Moving outwards on our journey through space, we come to the jewel of the solar system, Saturn, with its system of rings. It isn’t the only planet with rings. Jupiter, Uranus and Neptune have them, as well.

In the case of Saturn they are particularly well-developed. The rings aren’t solid. They aren’t like CDs or phonograph records, or something like that. The rings are an infinity of chunks of ice and rock, which are orbiting around above the equator of Saturn.

If you were within the rings, you might see chunks of rock about the same size as you are slowly orbiting around the equator of the planet.

Another thing about Saturn that’s particularly interesting is that it has a large moon, called Titan, which is completely covered in clouds.

It’s the only moon in the solar system that has an atmosphere to speak of. It’s twice as thick as the Earth’s atmosphere. It’s made primarily of nitrogen, like the Earth’s is.

But, in the case of Titan, which is very cold, water would be frozen solid. But there are other substances, like methane, like ethane, and other hydrocarbons, which could be in the liquid, gaseous or solid form.

So, weather on the surface of Titan would presumably be dominated by these hydrocarbons, like methane, rather than water. There is a mission on its way to Saturn which, among other things, is going to drop a probe through these clouds down to the surface of Titan to see just what the environment is like and, perhaps, to see if there’s any evidence for very primitive biochemistry that might possibly exist in this very cold environment.

The solar system gets increasingly spread out as we go from Saturn to Uranus to Neptune and finally to Pluto, the last of the nine planets.

Pluto is the one planet that hasn’t yet been visited by a spacecraft. There is one on the drawing board to go there in the next decade. So, the best information we have are fuzzy maps made by the Hubble space telescope.

Pluto is very small. It doesn’t really qualify as a planet and there was even a bit of controversy a year ago as to whether it should be called a planet at all, or whether it should be classified as some kind of icy asteroid.

But, all of us are very history-minded and we believe that Pluto should always be the ninth planet. So I’m not one to suggest that we demote Pluto.

But, Pluto is one of many, many chunks of material in the outer part of our solar system.

Beyond the orbits of Uranus, Neptune and Pluto, you will discover a belt of icy chunks, called the Kuiper Belt and around that – in a vast cloud that stretches half way to the nearest star – is what’s called the Oort comet cloud.

These are clouds of comet nuclei; chunks of ice a kilometer, 10 kilometers, maybe up to 100 kilometers in size.

Normally they sit out there. We don’t even see them, we don’t care about them, until every now and then one of them gets diverted inwards to the inner solar system and we get the wonderful phenomenon of a comet.

A comet is actually just a small chunk of ice a few kilometers in size that grows a remarkable tail of gas and dust.

There’s only comet nucleus that we’ve seen up close so far and that’s the nucleus of Halley’s Comet, which is about 10 by 15 kilometers – about the size of a small city.

Photographs indicate it’s mostly ice, but its got dirt and a crust of some kind of guck on it. There are places where the ice can evaporate. You can see ice evaporating to form the tail, which can stretch half way across the solar system.

While this may seem rather beautiful to see, you’ve got to realize that comets can be lethal. Comets and asteroids can occasionally collide with planets.

A few years ago a very interesting comet, called Comet Shoemaker-Levy 9, came close to Jupiter and broke up into about 20 pieces. Two years later, these chunks crashed into the atmosphere of Jupiter, one after another, disturbing the atmosphere.

Astronomers and lots of other people were able to sit and watch this spectacle unfolding, which was a constant reminder that every now and then these comets and asteroids collide with planets.

You can see one of these collisions every night, because little bits of the dust from comets swoop into our atmosphere, burn up, and we see them as meteors. Every time you see a meteor you’re seeing the collision of the Earth with a little bit of comet dust. That’s perfectly harmless.

If you’re really lucky, one of those collisions takes place with a little chunk of asteroid and the thing lands at your feet and we call it a meteorite.

A meteorite is a fragment of asteroid that comes through the atmosphere and survives the trip and is recovered on the ground.

The reason these are interesting is because some of these asteroid fragments contain carbon in the form of naturally-occurring organic molecules. What it shows is that these organic molecules can form in cosmic environments naturally, not through any biological process.

If you ever recover one of these, they’re worth several hundred to several thousand dollars.

On that note, we’re going to make a giant leap on our journey from our solar system into the realm of the stars.

I’m going to do that by mentioning a familiar constellation, which you can see rising in the East in the mornings these days --- the constellation Orion.

Orion has four stars around the corners and three stars in the middle that form the belt of Orion, the mythological hunter. That’s how you can recognize this constellation.

One thing you have to realize is the immense distances to the stars.

Light, which travels at 300,000 kilometers a second, takes years to come from even the nearest star. From some stars it probably takes several hundred or thousand years, because the stars that you tend to see in the sky tend to be the showoff stars that are particularly luminous, particularly distant.

You’ve probably heard that the Sun is an average star. The Sun is not an average star. The Sun is brighter and bigger and more powerful than 95 per cent of all the other stars in our galaxy.

Remember that when you look up at the night sky to view constellations.

When you look at Orion, one of the first things you notice is an immense cloud of gas and dust from which stars are forming.

This is precisely what we think happened with our solar system; that the Sun formed as the central condensation and the left over gas and dust formed into chunks that eventually formed into planets.

So one of the dominant questions of astronomy has always been: are there planets around other stars? And this is one area in which we’ve made tremendous progress in the last few years.

The idea is that in these discs of gas and dust planets somehow form. The problem is that you can’t see these planets at these immense distances. They’re too close to their parent star and they don’t produce their own light. So, they don’t actually make themselves visible.

But we can still see them and I want to take a minute to explain how that’s done.

It has to do with the fact that even if there’s a planet that’s unseen, the planet has sufficient mass so that it causes the parent star to move in a tiny orbit. For instance, Jupiter causes the Sun to move in a tiny orbit once every 12 years. But that orbit is very small.

We can determine the existence of planets because if a star moves towards an observer, or away from an observer, there’s a way of measuring that very precisely.

The German scientist, Joseph von Fraunhofer, discovered many years ago that if you took the rainbow of light from the Sun and examined it closely there were thousands and thousands of dark lines, or missing colours, that crossed this rainbow.

For one thing, you can use these dark lines to identify all the different chemical elements in the atmosphere of the Sun. This is the technique of spectroscopy, which is used in so many areas of science.

Furthermore, if the star is moving towards the observer all of the wave lengths get squashed and that makes them look bluer. If the star is moving away from the observer, all these waves are stretched and that makes them look redder.

If the star is moving sideways, then you simply see the normal spectrum with just the normal dark lines.

Using this phenomenon called red shift or blue shift, or the Doppler shift as it’s correctly called, you can, in fact, discover these wobbles in these stars and you imply the presence of planets.

So a number of groups in the world, particularly Jeff Marcy and Paul Butler, have detected planets around something like 20 other stars in our vicinity. The first multiple planet system has been detected around a star in the constellation Andromeda.

These are big planets. It turns out that planets the size of the Earth would not be detectable. There are, however, projects on the drawing board right now that would enable us to see planets that were almost as small as the Earth.

I would guess that in the next 20 to 30 years there will be missions within our solar system designed to look for planets like the Earth around some of the nearby stars. This will certainly be one of the most exciting discoveries of the next little while.

Let’s push on with our journey.

I mentioned that we know how the Sun works. It is a thermonuclear furnace and its core just keeps going for 10 billion years. But, like any other energy source this will eventually run out.

Without going into all the technical details, what happens is the core of the Sun shrinks as it tries to squeeze a little more energy out of the nuclei. The outer layers of the Sun swell up and in the Sun’s old age it will swell up and engulf most of the inner part of the solar system.

So if you ask what is the ultimate limit to life on the Earth, I would say it’s five billion years when the Sun swells up and becomes so powerful that basically the Earth fries.

Of course, we have other things to worry about in the next five billion years.

We can see one of these stars that has swollen up in the way I described. It’s the red star in the upper left hand corner of the constellation Orion and is named Betelgeuse. It’s the first star that was actually imaged, other than the Sun. Because it’s so large you can, even with the Hubble space telescope, see that it has a finite size.

What happens after it swells up is that the outer layers of the star simply drift off into space. The core of the star shrinks and becomes just a cinder. Its used up all its energy and it turns into what’s called a white dwarf.

One reason this is interesting is because the outer layers of the swollen star are expanding out into the universe where they can be part of the next generation of stars.

So, there’s a kind of cosmic recycling process that goes on with stars such as the Sun.

To give you an impression of the size scale, the Sun, when shrunk, would be no bigger than the Earth; the whole mass of the star now squeezed into the size of the Earth. Something like one teaspoon of this material would weigh 40 tonnes.

But it’s perfectly normal. Indeed, if we look around our neighbourhood in the galaxy we find lots of examples of these white dwarfs, these stellar corpses.

The brightest star in the night sky, Sirius, has a white dwarf which orbits it once every 50 years.

Procyon, another bright star in the night sky also has a white dwarf companion. This is the normal way that stars end their life.

But one star in a million dies in a more dramatic fashion. It explodes. Actually, it implodes. The core of the star is so dense that it can’t hold itself up any more and it simply collapses under its own weight.

The gravitational energy is liberated in the star and it blows off the outer layers of the star in a colossal explosion called a supernova.

One supernova observed at the beginning of this millennium, back in 1054 A.D., is now seen as a greatly-expanded cloud, called the Crab Nebula.

This turns out to be a very important process for life, because these supernova explosions take all of the elements that are created by nuclear fusion within stars and blast them out into the space between the stars where they can now become part of new generations of stars, planets and life.

It might interest you to know that every atom in your body, with the exception of hydrogen, was created within a star and was blown out into the inter-stellar material by a supernova explosion and at some later time became part of our solar system, our Earth, and eventually part of the biosphere.

You may remember that just a few years ago a young University of Toronto astronomer, Ian Shelton, discovered the brightest supernova in 400 years.

We hadn’t see a bright supernova for nearly four centuries. But it’s there in a nearby galaxy called the Large Magellanic Cloud, discovered at our small southern observatory in Chile which, because of government cutbacks in funding, had to be moved to Argentina. It was given to Argentina in return for a small fraction of the observing time.

That’s an interesting political story about just what government under-funding can do. It’s one of the most productive, small observatories in the world.

There’s a third way a star can die.

One star in a billion – the most massive stars end up in this very bizarre way. They collapse under their own weight and become so dense that nothing, not even light, can escape. They become a black hole.

The first example of a black hole was measured by my colleague, Tom Bolton, of the University of Toronto at the Dunlap Observatory in Richmond Hill.

What he did was to take a star that appeared to be producing high energy radiation, namely x-rays, and use the Doppler technique to see if there was anything unusual about the motion of this star. What he found was that this star was moving in an orbit around some unseen object.

By measuring this orbit, using the Doppler shift, watching as the spectrum was shifted to the red and then to the blue, he could determine the velocity that which this star was moving around the orbit and find out what mass of object it was orbiting around.

When all of the information was put together the conclusion that was reached was that the companion object was actually a black hole, a star that had collapsed under its own weight .

That was done at our own University of Toronto Observatory in Richmond Hill.

In fact, it is the kind of project that can only be done at a local observatory, near a university, that is under our control [and] that can be used regularly for days, weeks, months and years on projects of this kind.

I’ve talked briefly about live stars and dead stars and live stars and gas clouds and so forth.

Everything that you see in the sky with one or two faint exceptions is within our own galaxy. Our galaxy is our family or system of stars. There are 400 billion stars in our galaxy.

Can you see the billions of stars?

Yes, you can. If you go out at night in the late summer and it is clear and you look towards the south, you will see a hazy band of light called the Milky Way.

That hazy band of light is the billions of stars in our galaxy, merged together because there is just so many of them and they are so far away.

Look towards the constellation Sagittarius and there you see the centre of our Milky Way. The person who worked all this out was an interesting chap by the name of Harlow Shapley.

If I had to choose three people of the century who have made the most important contributions to astronomy, I think I would put him on my list. He was the one who determined where we are within our galaxy of stars. He started out as a journalist.

But the other way that our understanding of galaxies has taken form is by looking at galaxies other than our own. There are 100 billion other galaxies in the universe; all of them with billions of stars like ours.

Our nearest neighbour, and one almost like our twin sister, is the Andromeda Galaxy, so-called because it is in the direction of the constellation Andromeda. But it is much further away than the stars. It is two million light years away and that means that the light from this galaxy has been traveling towards us for two million years.

When I say that people normally ask, "could that mean then that this galaxy and its stars are no longer there?"

Remember, I said that the life times of stars were measured in billions of years. Not much would happen in even two million years. A few of the stars might die, a few more stars might be born, but things don’t change much in that period of time.

Andromeda has a couple of satellite galaxies. These are small galaxies that slowly orbit around the Andromeda Galaxy.

We and the Andromeda Galaxy undergo a beautiful slow ballet that takes billions of years as the two galaxies orbit around each other and may eventually collide.

Basically we and Andromeda belong to a little group of galaxies, called the Local Group. All of this was worked out by one of the other great figures of modern astronomy, Edwin P. Hubble, who started out in law and switched to astronomy. He would have to go down as the most important observational astronomer of the century.

My third figure of the century would be Einstein, who started off as a clerk in a patent office.

I want to outline a couple of mysteries about galaxies.

One is the mystery of the dark matter.

There is something in galaxies and clusters of galaxies in the universe which is invisible – you can feel it, but you cannot see it – that makes up 90 per cent of what is in the universe. We don’t know what it is. We have some ideas, but we admit astronomers don’t know what 90 per cent of the material in the universe is.

Another little mystery is that in the very centres of some of these galaxies there are millions of solar masses of material concentrated into a massive, but invisible object; a black hole.

Super massive black holes apparently exist within the cores of a large number of galaxies including ours. In our galaxy this black hole, is fairly benign; it is hard to see it.

But in some galaxies, that we see far out in the universe far back in time, these things are accumulating material and producing energy at up to 100 times the rate of our whole galaxy.

We call these Quasars.

When you hear the term Quasar it refers an intense point of energy that is apparently produced by one of these super massive black holes.

So there are some bizarre things out there in the universe and that should keep astronomers busy.

I want to mention a couple of other things that are keeping astronomers busy. One thing is mapping the universe. We want to map all of the galaxies in the universe.

Another thing that we are doing is using what we call the time machine effect. I mentioned that the Andromeda Galaxy is so far away that its light has taken two million years to reach us. That means that we see the Andromeda Galaxy as it was two million years ago.

The deepest image of space ever taken was a 10-day time exposure using the Hubble space telescope. It shows a little patch of sky containing thousands of very faint galaxies, some of them billions of light years away and, therefore, seen as they were billions of years ago. It means we can look back in time almost to the beginning.

What was the beginning?

The beginning was what we call the big bang.

The remarkable thing about the universe is that it is expanding. That was the other great discovery that Hubble made; expanding from a beginning that occurred about 13 billion years ago.

We can see back almost to that beginning and this is one of the major activities of my colleagues.

Astronomers in the Department of Astronomy at the University of Toronto are looking back in time, right back towards 12 billion years ago and looking at the rate at which stars have formed, looking at how stars and galaxies form and evolve with time.

Stars started forming 12 billion years ago. The rate increased as galaxies formed and now, as most of the gas and dust is formed into stars, the rate of formation of stars is gradually decreasing.

So what we are seeing is the history of the formation of stars and galaxies in the universe. This is being pursued by my colleagues and many others using the largest telescopes available.

I want to clear up one misconception. There is a misconception that virtually all astronomy is done with the Hubble space telescope.

It is certainly a marvelous tool, but there are many other important telescopes and there is none better than the Canada-France-Hawaii telescope, located in Hawaii and shared by Canada with France.

It is about 4,000 meters above sea level, above the cloud layer. It is a superb location, a superb telescope, with superb instrumentation. This has been one of the work horses of cosmology for many years.

Canada now has a share in a new project called, Gemini, which is two much larger telescopes, one in the Northern hemisphere and one in the Southern hemisphere. These two new telescopes are just coming on-line now. They will be the work horses for the next decade or two.

But not all the discoveries are made by professional astronomers.

The Rev. Robert Evans of Australia, an amateur astronomer, has discovered about two dozen supernovas. That puts him very high on the list of all of the astronomers who have discovered these objects.

These distant supernovas have turned out to be tremendously important in assessing how fast the universe is expanding.

What astronomers now sense is that this expansion is not slowing down as you would expect if gravity were starting to pull the universe back together again. The expansion is actually accelerating.

This can only be explained if there is some additional force in the universe above and beyond gravity which actually repelled material instead of attracting it.

Such a force was postulated in a mathematical way by Einstein and was discarded. This idea has been re-discovered in the last decade or so.

Finally, what other directions is astronomy going? Can we look further back towards the big bang than simply the most distant galaxies?

The thing that we can see the furthest back in time is what is called the cosmic background radiation. This is basically the radiation from the big bang which has expanded and cooled over 13 billion years. It now consists of radio radiation which reaches us from all directions in space.

A decade ago, a satellite made a map of this cosmic background radiation.

The actual interpretation of this map is somewhat difficult, but a lot of the regions of stronger and weaker radiation may represent areas where the universe was starting to congeal into galaxies, clusters of galaxies and so forth.

Being able to see this very early stage of the universe when this radiation was first formed may help us to understand what the universe is all about.

There is a whole series of projects that are just starting now.

One of my colleagues has just flown a balloon detector above Antarctica and is making a much better map of this cosmic background radiation.

There also are satellite projects due to go up in the next decade to make even more precise maps. From this we should be able to deduce a lot of the properties of our universe.

Finally, I would like to remind you of what Henri Poincare said about astronomy:

"Astronomy is useful because it raises us above ourselves. It is useful because it is grand. It shows us how small is man’s body, how great his mind, since his intelligence can embrace the whole of this dazzling immensity where his body is only an obscure point and enjoy its silent harmony."

I hope you will go outdoors, look up at the sky and enjoy that silent harmony.

Questions

What do you anticipate will be the major discoveries in astronomy in the next 20 to 25 years? Do you think it’s possible we’ll actually be able to observe the edge of time in space; in other words, the edge of the universe?

Let me answer the second question first. I don’t think we’ll see the edge of space. There’s a kind of built in limit to how far out we can see, because when we try to look out in space we’re looking back in time and eventually we get back to the beginnings of the time when the universe was opaque and we can’t see any further than that. But we will gradually unravel the events that took place at the beginning of time.

I didn’t say much about the big bang, but we know various things along the way from the beginning of the universe to the present. There’s a lot of gaps. I can imagine us filling in a lot of those gaps through a combination of observation, simulation and information that from particle theory and so forth.

* * *

What is known about the origin of asteroids?

Most of the asteroids do orbit in paths much like the planets and they are mostly between the orbits of Mars and Jupiter. This is the place where there should have been a planet formed in our solar system, but it never formed.

The catch, however, is that some asteroids don’t behave themselves. They don’t stay in the asteroid belt. They encounter other asteroids and there’s a sort of gravitational encounter where one asteroid gets thrown outwards and the other one gets thrown inwards and we find an asteroid then comes in on an orbit that could take it within the orbit of the Earth, or could actually take it on a collision course with the Earth.

So, every now and then one of these asteroids is on an orbit that could collide with the Earth. We call these near Earth objects – NEOs is one of the new buzz words of astronomers – and governments are actually doing something about NEOs.

* * *

Since some of these asteroids eventually may land on our head, is our technology prepared to face this problem [by] changing their orbit or smashing them?

It depends on which movie you watch.

The first thing to do – and governments are finally funding this – is do a survey. And it can be done with a relatively small telescope.

You do a survey and you catalog all of the asteroids that are big enough to do damage and are in orbits that could potentially be lethal.

At least then you’ve got a catalog and, in the course of doing that, you might be able to identify ones that could collide in 30 years or 50 years or 100 years.

There’s been a couple of cases where it looked they might collide in 30 years, but then a better orbit has shown there will be a clear miss.

We hope we won’t need this technology for 30 years.

There’s already ideas about how you could use some kind of nuclear device to change the orbit of an asteroid. But you have to be careful, because If you don’t do it right you’ll take an asteroid that could have missed the Earth and get it to hit the Earth.

Incidentally, that’s the reason why certain countries, like the United States, are getting rather concerned about whether their enemies could devise ways of deflecting asteroids so, that instead of missing the Earth, they’d hit New York City or something like that. There’s starting to be some serious thought about this and so there should be.

* * *

I’m struck by the decimation of most of the places within our galaxy. It seems to me we are the only people that have an atmosphere that produces human beings that think. Are we the only thinking beings as a result of this big bang?

As you pointed out, there’s only two possibilities: either we’re alone in the universe, or we’re not alone.

I’m not about the say that the universe is a place of desolation, though.

We have 400 billion stars in our galaxy. I don’t think it would be unreasonable to suppose that there were some kind of planet or satellite that was potentially habitable, or [on which] there’s a potential that life might form.

It’s entirely possible that the universe is far from being a desolate place; that there are numbers of places in the universe where life has developed and, perhaps, become more advanced than we are.

I think it would be very unreasonable of us to think that we were the be-all and end-all of the process of life and that nothing in the universe could equal us, let alone surpass us.

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How much does the government spend annually on research in this field and to what extent has government funding been cut?

It seems to me we’re talking about the consequences of something that’s going to be happening a million years away. It’s pretty hard to justify that right now in the real world when we’re facing AIDS and some other great research projects that might help people here and now.

I’ve heard also about the space station they want to build. What kind of realistic results are we going to see [that] are going to benefit people in the century to come?

In terms of asteroids, it seems a bit of a raison d’etre that they need to spend money on the space program to defend themselves against the Chinese who are spending millions and billions to try to deflect asteroids?

You’ve raised a whole bunch of interesting points.

One is that in the last 10 years there’s been significant cutbacks at both federal and provincial levels. Federal research funding is starting to bounce back.

Our small telescope was a victim of that time when there were intense cutbacks in virtually all levels.

A particular problem with astronomy is that in order to fund large new facilities you somehow have to give up the money from somewhere else. Unfortunately its meant that a lot of small telescopes have been closed down, even though they’re more cost effective than the large ones.

Again, it’s this problem of trying to do new things at a time when the total budget is being cut back.

You also mentioned the space station.

I’m not a great fan of the space station, either, though I’m aware it has some economic value.

I was pleased that the Canadian Space Agency has gone in as a small partner in the next generation space telescope, which is going to be a successor to the Hubble space telescope. I think about five per cent of that is going to be funded by Canada and Canadian astronomers will get about five per cent of the time.

In fact, one of my colleagues is the Canadian project scientist for the next generation space telescope. This is a long term thing, so the spending will take place over 10 years.

You also raised the question of what use is astronomy?

Sure, we could spend the money on medical research or something like that. But, again I keep coming back to the cultural value of astronomy. The fact that from earliest times its been an integral part of our culture.

One of the things I like about astronomy is it has tremendous potential for interesting children in science. I see children becoming interested in astronomy and dinosaurs. And they go and become engineers , something useful.

In the United States, NASA is now justifying a large fraction of its expenditures on a program called Origins. The emphasis is going to be on a series of programs that all relate to the origin of the universe, the origin of galaxies, the origin of planets, the origin of life, the search for Earth-like planets and so forth.

What NASA is trying to do is deliberately cash in the public’s interest in anything relating to what our cosmic origins are.

I guess now we’re coming towards the theme of this conference: how does astronomy connect with ethics, values and human destiny?

Well, astronomy is where we come from. That’s where the atoms come from, that’s where our planet comes from. Our star, the energy and, probably even life, is an astronomical phenomenon.

Couchiching Online History Table of Contents 1999 Summer Conference