This situation reminds me of sometime ago when a graduate student was asked to, well was arranged to,
defend his upcoming thesis and his talk was arranged.
It just happened to be so that his talk was scheduled at the moment
that there was a conference going on at this institute with several Nobel Laureates present.
So when the student started his talk he suddenly saw all these Nobel Laureates sitting on the front row.
So he panicked and he whispered to his thesis advisor, you know,
what on earth should I do with all these bright people on the front row, I just, I was asked to talk about my thesis.
And then the student advisor just replied, calm down, don’t panic, just speak slowly.
Now my problem.
My problem is to converse, I am stepping a little bit outside of my field.
My field is particle physics and elementary physics, quantum gravity and such
and I would have loved to talk about these topics but they have been already discussed so many times here
that I thought as being the last speaker I will discuss something slightly more frivolous, using only very basic laws of physics.
I think while standing here I will not be shot down by the front row but by the back row
because it will be simple physics and maybe students will see quicker what's wrong about it than all these bright people here.
I should mention that when I, long after I prepared this talk I realized I might have to rewrite the whole thing.
I had a little discussion with Jack Steinberger here who explained to me his interest in solar energy,
in particular thermal solar energy.
And one of the topics that came up was how do you convert AC current into DC current and back.
And I'd thought about this problem as one of those challenges that you have as a physicist.
You think as basic laws of physics we have an AC current, how do you turn that into a DC current
and back and the problem is easy enough if it's the current that you need for your laptop.
The problem is slightly more challenging if you're discussing millions of amps going through those currents
and I had thought about it a little bit.
I wanted to mention what I had thought about and then Jack said to me, you know t’Hooft, you’ve one basic flaw.
So I asked, oh what's that.
He said you think that you can figure out everything by yourself.
And that’s my problem indeed because this thought was about figuring things out just by yourself using basic laws of physics.
So before advertising, that is a wise exercise to do, a mental exercise.
I've had to tell you what the reasons are for advertising this after all.
I should say that what you have to do is use known techniques, not reinvent the wheel.
Why should you reinvent the wheel.
Well as a mental exercise always, it may be extremely useful to try to do this.
For instance, well before saying that you should try to do this I should first of all say that Jack is, of course,
damn right, that you shouldn’t try to reinvent the wheel, you should use known physics.
However, the excuse I have, it's really fun to try to do something.
I'll give some examples.
And one example is that when I was a student I was always thrilled by these enormously big construction cranes.
Now, the problem is a simple one.
The problem is you have a heavy weight here, you want to lift it over a high obstacle, like a building,
and put the weight on the building or somewhere else.
And you have a long arm and then you have a counterweight hanging on that arm on the other side,
just to make the whole thing stable and then you have cables and so on.
So when I looked at those construction cranes I thought what marvellous things they are
but there's something wrong with them and tried to figure out what's wrong with them.
And I thought what's wrong with them is this counterweight hanging high up in the air.
That looks quite unstable and I thought of how should this be done better and I came up, I thought,
with an idea that this counterweight should be at ground level and should be connected with cables to this arm.
And much to my surprise a couple of years later I saw more and more construction cranes
actually built exactly along that principle.
So I thought, gee, by knowing the laws of physics you might be able to look into the future.
Now this was a very simple example but maybe there are more examples of this thing.
Knowing the laws of physics you know what can be done and you know what can't be done and you know that much better
than the average science fiction author who writes novels about aliens and about space travel and God knows what.
And they use fancy laws of physics, which are not our laws so they can do things which normally you can't.
Now trying to figure out things by yourself has a big danger, of course.
One of the dangers is you can be wrong.
Of course, you're not as smart as a whole community of scientists who will figure out things
and eventually solve problems that you can't solve.
You might indeed be dead wrong and that means you’ve made a mistake.
Well as a physicist if you have some overview about what the laws of physics are, you might indeed try to avoid that.
Don’t be dead wrong.
In fact there's another very interesting law that if your theory is approximately right,
if you apply the laws of physics in an essentially correct way, you come up with a solution and that solution might indeed work.
But very often, or nearly always, you'll discover that someone else found a better solution.
Now this I will take for granted.
All solutions I will present in this talk will be just made up personally
and I'm sure there will be better solutions found by others later.
So I'm not going to advocate these solutions.
There's a simple example of this, another example.
I've been, as a physicist, been challenged with all sorts of problems facing humanity.
One of the problems is not energy but water.
There are enormous deserts on this plant, which are basically uninhabitable or practically uninhabitable.
What would happen if you could bring fresh water to these deserts and so I started to think,
what should one do as a physicist to bring fresh water to deserts? Well, the most urgent problem there will be desalination.
How do you turn dirty or salty water into fresh usable water, either in agriculture or directly for human consumption?
And I dreamt up all sort of principles which I would be able to think up.
How to get salt out of water in vast quantities, in big factories?
And I thought I had solved the problem and then I met an expert who said, yeah, you know,
you could do it that way and actually it's also done that way, but there are smarter ways to do it.
And he explained to me a very, very smart way to desalinate water using laws of physics, other laws of physics
that I hadn’t thought of, which are much better and energetically favourable
and I can discuss that if you want after, in the student session.
But, okay, if there is a solution, there is always a better solution that they can do.
In fact I discovered that the same way as a professional scientist when I was doing my PhD work,
which eventually led to a Nobel Prize.
And that was I was facing a tremendous problem that particle physics in general was facing.
This time I was equipped with the best possible knowledge of the problem and I knew the laws of physics,
which are relevant in that field, very, very well.
The problem was basically one called “renormalization” and to renormalize a theory in a way
that would make everything work in the theory of elementary particles.
And I was lucky enough to stumble into a solution which brought me the Nobel Prize.
So you could say, well that’s a big achievement, but then later it was discovered by others
that you could do the thing in a smarter way.
So even as a Nobel Laureate you can come up with tremendously interesting solutions
and later it is discovered it can be done better.
And I think all accounts you’ve seen given here about winning Nobel Prize were about how later the same thing
could be done much better and cleaner and faster and in larger quantities and so on and so forth.
And that’s always the case.
It even is the case also in theoretical physics.
So what I want to discuss is how you can use your knowledge of fundamental laws of physics to look into the future.
Your solutions won't be the best ones but at least the fact that solutions exist might be an indication
as to how they will be used later on.
Now there are lots of questions which are of interest here, so what can modern science do
and what are the things which will stay out of reach forever.
For instance in science fiction you can read many things about humanities future but you can certainly read things
which are fundamentally impossible and those are I wanted to identify and I want to identify things which might just be possible.
So for instance like can we solve our energy problem, today’s energy problems,
using advanced new ways and you can ponder about that a lot.
What can we do about climate change? You’ve heard talks about that.
Can we prolong human life span? Possibly! And how all this affects society and the question
which interests me very much is will humanity leave this planet or not.
Will we be able to conquer outer space and if so how far will we get?
In fact in the more distant future even this earth will eventually cease to exist.
Will humanity outlive that or not? All these interesting things are questions you can ask.
Unfortunately, I will not be able to discuss many of these questions here in this little amount of time that I have.
I've written down my ideas in a little book called “Playing with Planets”.
It was originally in Dutch but it's now being translated, it's nearly finished, translated by my daughter in fact.
And that will be available in a few months’ time and if you're interested in these topics I can recommend that.
So the few topics which I might be able to discuss in the time I have left are listed here.
Of course there's nano science, we've had a little talk about that but nano science of course
extremely intriguing and there are enormous future applications you could dream about in the more distant future.
So what can we say about possibilities and what can we say about restrictions?
What are the things which are not possible? Assuming that laws of physics we know today will have some eternal validity.
And here there's lots of confusion about physics in the community at large.
They think, or they seem to think that what we know now about laws of physics will probably be superseded
in the not so distant future by the complete converse.
So now we say E = MC2 but tomorrow we’ll say something else.
That’s not the case about physics.
In fact today’s physics is basically based on yesterday’s physics to a very large extent.
Newton’s laws have not been replaced by Einstein’s laws of physics at all.
Newton’s laws are still very much valid the way they are.
They don’t have infinite accuracy.
At some point it's better to use Einstein’s equations instead but that doesn’t mean that Newton was wrong.
Quite to the contrary.
He had things very precisely right but you could say more than just that.
And it holds for Newton’s laws, it holds for Maxwell’s laws and so on and so forth.
So physics is not changing.
These laws stay true so you better take them into account even if you think about what will happen in the more distant future.
So first of all those questions back on earth and of course,
well you want to apply fancy physics and one of the beautiful branches of physics,
which have been discussed in lots of detail in these meetings, is the physics
which we may possibly expect from LHC, the Large Hadron Collider Epsilon, which will hopefully reveal all the secrets,
many of the secrets that we now still don’t understand about elementary particles.
This is physics that refers to the atomic nucleus and the way the nucleus is being built up in even smaller components.
The atomic nucleus consists of protons and neutrons.
Those in turn consist of quarks, typically three quark in a proton, three quark in a neutron.
And then from there only go to see what are those quarks made of, what other particles are there and so on.
It seems, however, that this kind of physics will not directly affect humanity as you know it today.
You’ve heard many physicists say in the past, watch out, if you say such a thing the future might be different.
Maybe the physics now studied the LHC will have enormously interesting direct applications in the future.
But as we see it today that’s rather unlikely and I'm not going to count on it.
I'm going to use laws of physics as you know them today and then it's much more interesting
to look at the laws which are in the atom.
So for some reason this atom doesn’t want to move, yes now it wants to move.
And this is lousy picture of the atom suggesting that electrons move in elliptical orbits around the nucleus.
Well you probably know that quantum mechanics tells you quite a bit more than that.
You could, if you will, still identify ellipses in which the electrons move but the real message
of quantum mechanics is that the situation is quite a bit more complicated in the atom.
But these atoms have enormous potential for use in the future in all sorts of ways
and I want to refer now to a talk given back,
way back in 1959 by Richard Feynman and Feynman said something very wonderful in those days.
He had enormous foresight.
Remember 1959, nobody was really thinking about nano physics except Feynman.
Feynman said, look imagine how small the atoms actually are so what can you do with all that and imagine
that you could manipulate atoms as precisely as today we can manipulate pieces of wood or metal
and to make things, instruments and so on.
Suppose you can make instruments at the atomic scale, what could you do.
And he tried to fantasize what one could do if that were possible
and he tried as much as he could to stay within the known laws of physics
so he didn’t try to circumvent quantum mechanics or anything like that.
So he invented, he imagined what can you do.
And what you can do is, of course, basically make computer memories of that size, of atomic size.
If that happens that would mean that the information era, which we are now in, right,
we’re having computer chips with bits and bytes of memory stored on a small fraction of a square micron.
That can still be improved enormously.
Without violating laws of physics too much you can imagine that information can be stored in atoms and molecules
rather than on quantum dots or something like that, on chips.
So you can make them really very, very small.
In fact the existence of life and DNA molecules controlling life in living cells is a proof of that.
Information can be stored at the molecular level.
So the only thing is, can we ever control that and there's no law of physics telling us
that humans will not be able to control information stored at the atomic level.
But that would mean that the information era indeed has just started.
So that means computer hardware can still be improved enormously, at least in principle.
It's not hard to say that.
It's also not hard to say where the limit will be.
The limit will be you can't store much more information than one bit or so per atom
and then you reach some sort of ceiling, it's just going to be very, very difficult to improve.
We also know that there are such features as quantum mechanics so quantum computer could,
in principle, do better than that but there are enormous limitations as well for the quantum computer.
Anyway, what you have today is so called Morris Law.
Morris Law, well many of you have heard of it, it was already mentioned here also,
once every 1.8 or two years or so the amount of information that you can store on a chip can double
and if you block that, logarithm against logarithm, you get essentially a straight line,
which means that if this is expected to continue you'll get tremendous amounts of information
that you can store on a chip or something and to be used for computers.
And this line does not show much of a sign of flattening off.
It's a little bit flattening.
I think it's now rather than 1.8 years, it's rather two years that you have a doubling period,
but still this happens essential of straight line.
If you take the atomic scale as a fundamental limit, this line can still continue to rise for decades on end,
which means that we are very far off from the limit where computers can go and that means, of course,
that you're only at the very beginning of the information era.
There's enormous things you can do with information.
So my conjecture is in the not so distant future all information will be essentially trivial to obtain.
And that includes intelligence.
So here there's something where people differ, have different opinions.
Many, even science fiction authors, but also ordinary scientists often think that intelligence of a human nature
will be impossible to use in a computer or have a computer be as intelligent as a human will never happen.
Well, I think I differ, my opinion is different.
I think there is no fundamental obstacle at all to put human kind of intelligence in a computer or even more.
Once you understand how to programme that, which is extremely difficult.
It may take many more generations of smart computer programmers to realize that but there's no fundamental reason whatsoever.
So I, well I am too sober a physicist to believe that human brain has anything to do with quantum mechanics.
I don’t believe that.
Some people do, but I don’t, and so I think the human brain is basically not much more than a fancy computer
made with much, much better hardware and much, much better software than today’s computer.
But that won't last forever.
And as a rule, the rule is that once you can make machines which do the same kind of job as living organisms,
like a machine that runs or a machine that flies or a machine that digs, if that’s a dedicated machine
that we have constructed to do that, that machine will perform much better than living organisms today.
Machines that dig can dig much deeper than any animal.
Machines that fly can become much larger than any flying animal.
So I also think that machines that think and that are intelligent,
once they can be constructed they’ll be a lot more intelligent than humans and not less.
And of course the social consequences of such a thing are very, very difficult to predict.
And then, of course, you think of robots, automatically moving machines,
basically either remotely controlled by computers or directly controlled by electric circuitry inside.
Those are, in principle, possible.
Then they can be miniaturized, they can be made very small.
But then when you say such a thing, and again science fiction stories about that,
then I come with my first physical law saying there's a limitation.
There's a law against it.
And what's that? Well there's laws against very tiny robots having very sharp eyes.
Robots, if they're very tiny, they will have very bad eyes and there is a very fundamental law of physics saying that.
If you have a detector, the bigger your detector is the higher its resolution.
So our human eyes are this big so they have the resolution that you are familiar with.
But an insect has much, much tinier eyes so their eyes must be much worse as a detector.
There's nothing you can do about that.
So a fly has rather poor eyes.
In fact you can see the resolution of his eyes if you look at all these segments of the eye on its head.
Well that’s a very poor resolution with which the fly can see and it shows,
for instance a fly cannot see the dirt on a window so it flies against the window all the time.
A fly cannot see a spider’s web.
In fact spiders live by that piece of knowledge.
We can see the spider’s web but the flies cannot.
So even each other, one fly cannot see another fly any better than we can.
In fact our ways of seeing those two flies sitting together is much sharper than what they can do.
So often people don’t realize this.
However, you could think of very, very smart software but if you have a thousand microscopic robots
you could probably combine the information and effectively the eyes become a thousand times bigger
and then you might generate sharp images again.
So that’s the way I think how you can use laws of physics.
Well now technology, these are fancy pictures you can pick up the web, you know,
this is what people dream about when you think of doing what Feynman wanted to do.
Manipulate atoms, atom by atom.
Well imagine if you can make tools like this that the end will not be in sight
and today’s tools will look like they’ve come from the Stone Age no matter how fancy they look.
So whether this will be realized, well I can imagine very well that maybe I'm jumping too far now,
there might be obstacles of a kind that I don’t know about which make this actually very difficult.
Certainly, it's not possible today.
What is possible today is a study about genes and large molecules
and the like and really now you see some merging of nano technology on the one hand and biology on the other.
I think Brian Josephson talked about that basically and you can really think that with using nano technology
you can enter into the province of biology where the scale is typically a couple of nano metres.
Genetic engineering is one of the subjects which I think will have an enormously bright future.
Now maybe the biologists among us will correct me here,
but I think that genetic manipulation is only beginning to be a technique that humans are starting to use.
I think there's enormous potential to solve many of the problems that humanity is facing today,
such as the food problem, the energy problem, water, desalination.
Maybe in the future we won't use just plants of a kind that we’re using today.
Maybe in the future we’ll use organisms to desalinate water by just clever genetic manipulation.
After all, remember that if you use DNA, today with much effort people can read the DNA code.
They cannot really write very well yet so today writing DNA codes is possible but the way they write DNA codes
is like if you want to write a new book you take a book, an existing book, and take another existing book,
you tear out a page and you glue it in the other book and that’s the way people write DNA today.
Now actually you take a part, a random part of an organism, you paste it into this organism and then you have something new.
I don’t think that’s the best way of writing books but I don’t want to insult my colleagues in biology, by the way,
because what they are doing is tremendously interesting and advanced technique.
What I'm just saying is that this might not be the end of the road.
Eventually, you want to write your DNA code first on your floppy disc or on your hard disc
and then press a button and out comes the DNA thing exactly as you designed it.
I think in the distant future sometime that should be possible.
I don’t see any reason why it should not be possible but it will take time and lots and lots of effort
and further research to reach that situation.
Okay, we have been on earth, it's about time to try to get off the earth and ask what's new.
What can humanity do in the cosmos? Well, all laws of the cosmos, the visible part of the universe that we see in our microscopes,
in our telescopes, the visible part of the universe is controlled by exactly the same laws of physics
as the laws of physics here on earth.
So this fact has been established abundantly so when we try to think about humanity leaving our earth
we can use the same laws all over again.
Now this is how science fiction fantasts imagine that you'll travel out to other stars.
This is definitely not going to be the way it's going to happen.
For instance, this thing seems to be hanging and there is of course no gravity in space.
So this picture is all wrong, this is not established laws of physics.
You have to do something else if you want humanity to conquer outer space.
Right so, science fiction authors came up with something smarter, the black hole.
And even serious scientists are backing them up saying that maybe a black hole is a wormhole between here
and other universe or other part of universe.
Can you use that for travel? Well I know the laws of physics of black holes and I know what they cannot do.
And unfortunately the black holes cannot be used as a wormhole for transportation,
even though you read about this every day or so in science fiction novels.
Why can a black hole not be used? Well black holes not only have strong gravitational fields,
they’ve also very, very strong tidal fields.
The tide is generated because the moon moves the earth, we’re acting on basically centre of gravity of the earth in the middle.
But the water is on the surface of the earth and that could be closer to the moon or a further distance from the moon
than the centre of the earth.
Therefore, water on the surface of the earth is either attracted towards the moon or away from the moon,
depending on where you're looking and so that causes tidal movement.
That is a differentiation between the gravitational fields nearby and faraway.
That same tidal force near a black hole is much, much stronger and there's a simple way to estimate the effect
of the tidal force of a black hole.
All you need to know is how much time does a light ray take to go through, to travel the distance
of the size of the black hole.
Now think of a black hole as heavy as the mass of the sun, which is a very heavy black hole.
Its size would be about three kilometres or so.
So the time scale that’s relevant for that black hole
is three kilometres divided by 300,000 kilometres per second that a light ray takes.
So the timescale of that black hold is one hundred thousandth of a second.
Now to estimate the tidal force that’s generated by that if you come too close,
all you need to do is imagine that you're in a roundabout and a roundabout makes a certain number of revolutions per second,
or per minute, and how do you feel in that roundabout.
You could also sit in a centrifuge and the centrifuge starts to rotate.
Now I can, as a person I can rotate it in one second and I don’t feel very dizzy so a second is a decent timescale
for the force of it but if you rotate it very fast you feel that your head is being pulled in that direction
and your feet are being pulled in that direction.
Now imagine how you would feel if you sit in a centrifuge that rotates a hundred thousand times per second.
Of course, you will be torn to pieces and your head will go there and your feet will go there and you'll die.
So there's no way in which you can go into a black hole as big as a solar mass because the timescale
there is a hundred thousand per second.
Are you suggesting that I should stop?
Oh that is, let me see here.
Yes, I'm going to, ah this is not the picture I should have.
I'm trying to see some of me… I wanted to say a few more things about intelligent robots and that is this.
But maybe my time is running out.
So I've been travelling to the moon and travelling to Mars and eventually I don’t like, I'll say just a few things about this.
You have probably heard about attempts to send people to Mars and back.
My worry with that is the following: If you send people to Mars and back that project,
which has been seriously announced by the American President and later NASA is trying to have such a programme like that.
I'm very worried about that programme because what will happen.
Someone will go to Mars, or a couple of people go to Mars and they come back.
And then afterwards, after a while they’ll send another mission to Mars and they will come back.
And perhaps two or three or four, or perhaps ten times, it’ll just go like people have gone to the moon.
They go to the moon and they go back, go out onto the moon and go back.
After a while they get bored and there's no money anymore and no-one stays on Mars, like now no-one stays on the moon.
So they’ve been there, they come back and nothing happened after.
So I would like to see a more permanent human presence on Mars like on the moon,
so I think this has to be done in much smaller steps.
First try to get permanent presence on the moon and then try to get permanent presence on Mars
and for that I was thinking of having intelligent robots.
Assuming that intelligence can be put in a computer, not directly but step by step, get more and more intelligent robots here.
Robots are very central in my picture of the human future.
Eventually, I'm thinking of John von Neumann who was thinking about intelligent robots
and I was thinking about reproducing, self-reproducing robots.
Now self-reproduction is a very interesting thought so making robots that can reproduce themselves
would open up a large part of universe for humanity.
You see, one of the things I've no time to discuss is that actual journeys to nearby stars,
it would cost millions of years rather than thousands or even hundreds science fiction authors want you to believe.
It would take millions of years and for humans there's no good use to do that.
But the robots eventually could be patient enough to make such a trip step-wise.
They don’t go to the stars directly, they go via the intermediate object in the Oort Cloud or Kuiper Belt.
They are objects they will travel to, eventually they will reach those other stars, very, very slowly.
But for that you need self-replicating intelligent robots to do that.
And, okay I'll have no time for this, I'll just go to the skies.
So humans will not go to the skies but their machines will.
Now it's very important to realize that the laws of physics that hold for us will also hold for alien civilizations,
no matter how far in the galaxy they are, or how far in the cosmos they are.
So it's very unlikely that aliens made of flesh and blood will ever visit us.
We are too far away.
They can't reach us.
The only thing that they can do is they can send their Neumannbots, as I call these things,
because they're subject to the same limitations.
And the question now is have they done that or not.
And okay as I see it their Neumannbots simply didn’t reach us because we have no trace of that whatsoever.
Again, this is where I'm sticking my neck out.
Some people say yes we've UFOs all over the place, it has been seen by many people.
I don’t believe any of that.
I don’t think they’ve really seen UFOs.
So I actually strongly suspect that no alien life form has ever been able to reach us, even closely, not even their machines.
And this has an interesting implication, like Enrico Fermi who already remarked, you know,
where is everybody, where are all these aliens, they are not here for sure, why didn’t they come.
And my answer to that is most likely they aren’t there.
Most likely in our galaxy there's hardly any intelligent life
because if there would be there would also be intelligent life which originated billions of years ago.
In billions of years robots or whatever have time enough to reach us or to reach every single corner of the galaxy to colonize it.
For some reason that hasn’t happened and my belief is it hasn’t happened, not because it's impossible,
but because it's very difficult to generate, to have life generated spontaneously anywhere in the universe.
I think we on earth are the exception.
So life forms are very hard to create and not very easy.
I think, well many scientists disagree with that, by the way.
Many scientists think that everywhere where you have inhabitable zone around some star
there’ll be life eventually, intelligent life.
I don’t believe that.
The origin of life is actually extremely difficult because life is the prime example of a Neumannbot,
a thing reproducing itself spontaneously and you might have thought that’s going to be very hard to make.
Yes, so hard it's even hard to make for nature.
So my belief is that nature will have a very hard time making self-replicating objects, which is what we call life.
And for that reason I think the origin of life is a very improbable event.
It happens every now and then in a universe but not very frequently.
So I have some bets going on with people saying they won't find any life on Mars,
they won't find any life on Jupiter’s moons or Saturn’s moons or anywhere.
They won't even find life on the actual planets that they are investigating.
There may be life otherwise at other spots in the universe that’s very far away.
I'm the last speaker here so I want to end my talk also by thanking in particular the Bernadotte Family
for being so tremendously hospitable to us.
Their hospitality was greatly enjoyed, I think students enjoyed that but the Laureates here also have had a great time here
and we hope that these meetings will continue for many years to come.
Thank you very much.