One of the great revelations of the age of space exploration

is the image of the earth, finite and lonely, somehow vulnerable

bearing the entire human species through the oceans of space and time.

Here we are on a planet which is about five thousand million years old,

the sun around which it goes is not much older

it is part of a galaxy which is perhaps ten or twelve thousand million years old

which is one of perhaps hundreds of thousands of millions of other galaxies...

Humans have been on this planet for something like a million years

and for the vast bulk of that time things changed extremely slowly.

The population increased very slowly,

our technology increased and improved by very slow steps

and just recently we had a huge increase.

It's what's called an exponential,

it's flat for a long time and then... boom!

it's an increase in population,

increase in technology, increase in pollution

increase in our powers to disturb the environment

to change the planetary environment

but we're the same old human beings as we were a thousand years ago

or a hundred thousand years ago,

not much has changed with us

and so it's very hard for us to catch on

that there's a new situation, and we have to adapt to it.

On the other hand, that's one thing we humans are good at...

adapting, figuring out

We're smart. That's our principal advantage over all the other species

I mean we're not faster, stronger, better diggers,

we don't fly all by ourselves.

What we do is figure out and build because of our hands.

The ancient myth makers knew

we're children equally of the earth and the sky

in our tenure on this planet we've accumulated dangerous evolutionary baggage...

propensities for aggression and ritual,

submission to leaders, hostility to outsiders

all of which puts our survival in some doubt.

But we've also acquired compassion for others,

love for our children,

a desire to learn from history and experience

and a great soaring passionate intelligence.

The clear tools for our continued survival and prosperity.

Our ability, to understand things instantly

so called common sense

derives from a certain range of size and speed and duration

that are appropriate for human existence.

We know about things from a tenth of a millimetre

to a few kilometres

from a fraction of a second to a lifetime

and so on.

So when we are dealing with matters of quantum physics

where particles are the size of 10^-13th centimetres

or in cosmology where we are talking about

ten billion light years or more,

it is very reasonable that our intuition

is not adequate to the task.

Fundamental changes in society are sometimes labelled impractical or contrary to human nature,

as if there were only one human nature

but fundamental changes can clearly be made

we're surrounded by them

in the last two centuries abject slavery,

which was with us for thousands of years,

has almost entirely been eliminated

in a stirring worldwide revolution.

Women, systematically mistreated for millennia

are gradually gaining the political and economic power

traditionally denied to them.

and some wars of aggression have recently been stopped

or curtailed, because of a revulsion

felt by the people in the aggressor nations.

If a five or six year old asks why the moon is round or why grass is green

the usual adult answer, at least in my experience

is to discourage the child.

say 'what shape did you expect the moon to be, square?'

or 'what colour did you expect the grass to be, blue?'

instead of saying that 'those are interesting questions, lets try to find out the answer'

or maybe nobody knows the answer

and when you grow up you'll be able to discover the answer.

It would be very healthy for the human species if there were

less discouragement and more scientists.

It's not that pseudo-science and superstition

and new age so-called beliefs and fundamentalist zealotary are something new

they've been with us for as long as we've been human

but we live in an age based on science and technology

with formidable technological powers

science and technology are propelling us forward at accelerating rates

that's right and if we don't understand it

and by we I mean the general public

if it's something that 'Ohh I'm not good at that, I don't know anything about it'

then who's making all the decisions about science and technology

that are going to determine what kind of future our children live in

just some members of congress?

but there's no more than a handful of members with any background in science at all

and this combustible mixture of ignorance and power

sooner or later is going to going to blow up in our faces.

I mean who's running the science and technology in a democracy

if people don't know anything about it?

Science is more than body of knowledge it's a way of thinking

a way of sceptically interrogating the Universe

with a fine understanding of human fallibility

if we are not able to ask sceptical questions

to interrogate those who tell us that something is true,

to be sceptical of those in authority,

then we're up for grabs for the next charlatan

political or religious that comes ambling along

it's a thing that Jefferson lay great stress on

there wasn't enough said that to enshrine some rights

in the constitution, or the bill of rights

the people have to be educated

and they have to practice their scepticism in their education

otherwise we don't run the government

the government runs us.

The global balance of terror

pioneered by the United States and the Soviet Union

holds hostage all the citizens of the earth.

Each side persistently probes the limits of the other's tolerance

like the Cuban missile crisis,

the testing of anti-satellite weapons in the

Vietnam and Afghanistan wars,

the hostile military establishments are locked in some

ghastly mutual embrace.

Each needs the other

but the balance of terror is a delicate balance

with very little margin for miscalculation.

and the world impoverishes itself by spending a trillion dollars a year

on preparations for war

and by employing perhaps half the scientists and high technologists on the planet

in military endeavours

We have let all sorts of social programs languish

as we have permitted the amount of poverty in children to increase

before the end of this century more than half the kids in America may be below the poverty line.

What kind of a future do we build for the country if we raise all these kids

as disadvantaged, as unable to cope with the society,

as resentful for the injustice served up to them...

This is stupid.

and then what happened with the resources is they went into increasing budgets for arms

isn't that where the money went?

That, and making rich people richer.

The money all gets re-invested,

if you've got money you put it in the bank

the bank lends it out to people

to people to buy homes and cars

But not poor people, but not poor people.

well that's a good..

It tends to stay up at that highly stratified, very...

so more people employed with capital formation...

I believe that the government has a responsibility to

care for the people.

I'm not talking about dole,

I'm talking about making people self-reliant

with people able to take care of themselves

there are countries which are perfectly able to do that,

the United States is an extremely rich country

it's perfectly able to do that.

It chooses not to.

It chooses to have homeless people.

This country has vast wealth,

just look at something like Star Wars [The Laser anti-missile defence system]

they've already spent $20 billion on it

if these guys are permitted to go ahead they will spend a Trillion dollars on Star Wars...

Think of what that money could be used for.

To educate, to help,

to bring people up to a sense of self-confidence.

We are using money for the wrong stuff.

So, that's another calibration of how serious the

stakes are these days, how high the stakes are

putting greenhouse gases into the atmosphere

promises, if that's the right word...

a global catastrophe.

In the particularly field that I'm involved with

the exploration of planets

there we have opened up a universe of wonders

we have looked close up at dozens of new worlds

worlds that we never saw before

when you study these other worlds you learn about this one

it's a very important fact

by comparing our world with other worlds you can see a lot of things that can go wrong

Venus for example has this immense greenhouse effect

the surface temperature is hot enough to melt tin or lead.

Anybody who says the greenhouse effect is just some fantasy...

all you have to do is look at Venus

very important object lesson.

You put gases like Carbon Dioxide or CFCs

other greenhouse gases into the atmosphere

over this country...

They don't stay over that country,

those molecules don't have passports,

they don't know about national sovereignty,

that's something they've never heard of.

The atmospheric circulation spreads those gases all over the planet

and so what one country does affects all the other countries.

That's serious stuff.

The depletion of the ozone layer lets more ultraviolet light from the sun down

to the surface of the earth.

Skin cancer is a serious consequence

but there's a more serious aspect of it is...

that the ultraviolet light attacks the little one-celled plants that are at the base of the food chain

those are the guys that the next guys eat

and the next guys eat and the next guys, next guys

and way at the top of the ecological pyramid there's us.

we're ultimately eating the one-celled plants that have been processed through lots of intermediate

plants and animals

and it's, it's clear that very thin atmosphere, it's so sensitive to the depredations of human beings

you look at that and you say 'hey that's only one little world'

We don't have anywhere else to go.

No other planet in the solar system is a suitable home for human beings,

it's this world or nothing.

That's a very powerful perception

and, so again

we're messing around the global environment

in a very serious, very stupid way

and we just have to get our technology ahead

it's not enough to say that corporations can

do whatever they want as long as they make a profit,

not if they're putting at risk people all over the world.

They can't.

There has to be a new way of approaching this

and we can't say that one nation can do what it wants within its borders

because as I've said before, what you do in one countries borders

has consequences all over the planet.

The solution to these kinds of problems has to be that everybody on earth works together.

and so I think there's a

certainly a chance of us getting out of this mess

but not by business as usual,

not by the idea that we shouldn't plan ahead,

not by the idea that anybody can do whatever the hell they want

and it doesn't affect the environment...

So, there has to be a new way of looking at the future

and that is that we are all humans and that we are the same species

on one fragile little planet.

We are all in this together,

and we have to work together.

That's kind of the silver lining of these crises,

they are forcing us to become a planetary species.

Which aspects of our nature will prevail is uncertain

particularly when our visions and prospects are bound

to one small part of the small planet earth.

But up there in the cosmos an inescapable perspective awaits

national boundaries are not evident when we view the earth from space

fanatic ethnic or religious or national identifications

are a little difficult to support when we see our planet as a

fragile blue crescent fading to become an inconspicuous point of light

against the bastion and citadel of the stars.

The old appeals to racial, sexual and religious chauvinism,