We did something which most people consider to be a bit of a heresy.
We decided that the speed of light could change in space and time,
and if that is true then our perceptions of physics will change dramatically.
At the dawn of a new century, a new theory is being born.
It threatens to demolish the foundations of 20th century physics.
Its authors are two of the world's leading cosmologists.
If they're right, Einstein was wrong.
It all began when Andy Albrecht and Joao Magueijo met at a conference in America in 1996.
This was a pretty exciting meeting in Princeton. Most of the key people were there,
there was lots of debate about the contemporary issues in cosmology.
Joao came up to me late one evening just when I was ready to leave I think
and had a very interesting idea.
This is total bullshit! It wasn't like that at all.
It wasn't like that.
Well it was late. It wasn't like that.
How was it, Joao, how do you remember it?
Right let's start this shall we.
The story as I remember it was, at least when I was present, was
this conversation between the three of us, and then each one of us suggested something.
I remember I suggested the varying speed of light and there was embarrassed silence.
I think you two thought I was taking the piss at this point.
Maybe, possibly, but...
But then, oh he's actually serious, he's not laughing;
then we started, we took it from there actually, we started taking it more seriously.
For most scientists the idea that the speed of light can change is outrageous;
it flatly contradicts Einstein's theories of space and time.
But recently astronomers have begun to realise that the Universe
doesn't always behave as his theories would lead you to expect.
We're making measurements which indicate
that the Universe is filled with some kind of energy density.
We don't understand this energy at all.
It's unlike anything else in physical theory.
And the surprise is that instead of the Universe slowing down,
in fact it's speeding up.
It's certainly a very profound result for physics
because it will be the first ever indication that the laws of nature
were not always the same as they are today.
Who knows what's in store? I think in some way it's a very exciting time:
it's very similar to the revolution that was seen in physics at the turn of the last century.
So here we are about to enter the new millennium with a whole lot of uncertainties in store.
To understand what's at stake, we need to go back to that scientific revolution.
It began here in Bern Switzerland in 1905.
As the new 20th century dawned, the intricate mechanism of 19th century physics
was beginning to show signs of strain.
It was finally demolished, not by an established scientist, but by a patent clerk.
When Einstein started his career, we still lived in a Newtonian clockwork Universe.
Space and time were simply a reference system.
The metre was a metre, it was a meter anywhere you went,
and time clicked at a constant rate throughout the whole Universe - the second was the same.
It was unaffected by where you were, whether you were moving.
Time was considered as an absolute concept
the time would be everywhere the same, independent of the state of motion of somebody.
That there would exist an absolute time which could be measured with a clock like that one.
This was probably the concept which Einstein
kind of smashed with his new thought.
The tool that Einstein used to shatter the clockwork Universe was the speed of light.
He knew that for 20 years scientists had been puzzled by an experiment
which suggested there was something decidedly odd about the speed of light.
In the 1880s two American scientists, Albert Michelson and Edward Morley
set out to measure how the speed of light was affected by the Earth's motion through space.
They set up an experiment with beams of light.
In this experiment there's a light source which is the laser,
and really what one's doing is splitting the laser beam into two
sending them in two directions at right angles,
and measuring in a sense the relative speed of light along those two beams
and recombining them here.
The pattern that you see is the interference between two beams
and it's measuring the relative speed of light within those two beams.
If the apparatus were static there'd be no reason to expect a difference between the beams,
but in fact it's moving very fast indeed.
Our planet orbits the sun at 30 kilometres a second.
It also spins around its axis once a day
so every laboratory on Earth is spinning through space.
Well at this time of day
the Earth is essentially moving in this direction through space round the sun.
If we then waited six hours, the Earth would have turned
and then this direction would be the direction of motion of the Earth through space;
then in another six hours this direction would be back but reversed.
So that by doing nothing you can just sit here and very, very smoothly the Earth takes you round
and then you can just look at the stability of your apparatus.
Michelson and Morley assumed that the planet's speed
would add to the speed of the light beams and their apparatus.
So they expected to see a regular pulsing of the pattern every six hours
as the Earth's motion added to the speed of light in first one beam and then the other.
The surprising thing of course was that the measurements showed that nothing happened,
and no matter how they did it and when they did it and whether they waited a long time,
all year even, still nothing happened.
And that's the beauty of the experiment that if you can measure nothing very, very precisely
then you've got something really important.
The importance of this result was that it proved
that you can never add to or subtract from the speed of light.
This was a direct contradiction to what was supposed to happen in the clockwork Universe.
When space and time are fixed, speeds must always add up.
In such a world one has a very simple rule for the addition of speed, the addition of velocities.
In Einstein's example, if you're walking along a tram or a train,
your speed, with respect to the ground outside,
is just the sum of your speed walking along the tram
and the tram speed with respect to the ground.
But the Michelson, Morley experiment had proved that this was not true for light.
Light leaves the tram at the speed of light
and strikes the pedestrians at the speed of light
and this speed never changes, no matter how fast the tram is going.
But something must change as a result of the tram speed.
Einstein realised that it must be space and time themselves.
Once you assume that the speed of light is the fixed thing,
this will imply that space and time can no longer be fixed and that,
for example, a moving clock which is moving with respect to you goes slower.
So, viewed from the pavement, the speed of the light from a tram is not affected by its motion.
Instead the watch, as the passengers are waiting, will run slow compared to a stationary clock.
In a small two-room apartment a few yards from the clock tower,
Einstein wrote up his radical theory of Special Relativity.
Advertisement for the unemployed Einstein offering...
he offered private courses in mathematics and physics for students.
For some time he was unemployed; nobody wanted him.
They thought he was too lazy.
I think they thought he was too troublesome.
Does it say there how much he charges?
It says that there are test lessons for free.
Ok, I think I'll come by and have a test lesson.
But Einstein's fortunes were about to change.
So it's 1905, he's 26.
A very penetrating gaze.
In that year he published several papers of which Relativity was just one.
Six papers if you count the PhD dissertation. In one year.
In one year. And each one founds a field of physics.
And each one is worth the Nobel Prize.
I wonder if he'd realised
just how big a change he was making to the world when he wrote that down.
And that's the e=mc˛ paper, which he published very shortly after that one.
Look how thin it is! Jesus! Three pages.
if I could trade all of my lifetime publications for these three pages!
But Einstein himself was not satisfied.
The problem was that his theory of relativity broke down when gravity entered the picture
and gravity was the dominant force in the Universe.
Einstein realised that he had to take his notion of flexible space and time even further.
He had to give space-time actual properties,
it was no longer just in an empty place where things occur,
it was something that actually was interactive with.
So in his famous statement, mass tells space how to curve,
the presence of mass actually curves space-time.
And in the flip side of that, his next part of this statement is:
space tells mass how to move,
so a mass moving through space-time now just follows the curvature induced on it
by the presence of a mass.
And this solved an old problem from Newtonian mechanics: the Earth is going round the sun.
The Earth feels a gravitational attraction to the sun. How does it do that?
How does the Earth know the sun is there?
What is the source of this instantaneous action at a distance?
In Einstein's model there is no such instantaneous action at a distance.
The mass of the sun simply curves space-time
and then the Earth follows that curve.
Just like this tram follows the tram line it is on in response to the local curvature of the tracks;
it doesn't know if those tracks are going to curve some distance in advance;
it doesn't need to know. It just follows the local curvature of the track.
Einstein realised that it wouldn't just be mass that would cause gravity,
it wouldn't just be mass that curved space time.
Every form of energy, like heat or also pressure, reacts to the gravitational field.
There's nuclear energy ­ many, many different types of energy
and all of them cause space-time to curve the same amount,
depending just on the total amount of energy present.
Mass is nothing special in this regard.
For 10 years Einstein searched for an equation to express this relationship
between mass-energy and space-time. In the end it was stunningly simple.
G = 8 p T.
In five characters the Einstein field equation encompasses the structure of the entire Universe.
It ranks as one of the supreme achievements of human thought.
When, as a student, you learn this theory you find it extremely beautiful and simple.
But then if you think: how did he get it? How on Earth did he find out these equations?
That's a miracle, I mean still now you can't really understand how he got there.
But Einstein didn't stop.
He set out to use his new equations to describe the entire Universe.
It was a bold leap and immediately he ran into problems, problems which still remain.
Relativity was a great success
at least until Einstein had the courage to apply relativity to the Universe as a whole.
He invented cosmology, scientific cosmology,
but at the same time he gave us a lot of problems which are still with us.
Basically, the Universe as we see it doesn't want to be like that according to relativity.
Einstein's approach was based on a daring assumption.
He knew that locally stars would distort space-time
in complicated ways that would be too difficult to calculate.
But he believed that if he stepped back far enough,
all the matter in the Universe would look like molecules in a cloud of gas.
The cosmological fluid.
From this perspective, the shape of space-time would be uniform and simple enough to deal with.
But when he began to calculate how the Universe would behave under the influence of gravity
he got a nasty shock.
You look out in the Universe
and you see what appears to be relatively stable: the unchanging stars.
And in Einstein's era they thought the Universe was remarkably static.
It looked the same over time. But in Einstein's solutions this couldn't be true.
Einstein found that his equation predicted that all the matter and energy in the Universe
would fold space-time back upon itself.
Soon the Universe would meet a fiery end as all the stars and galaxies
collapsed into an enormous fireball.
And in order to prevent this, Einstein had to add a term
which he called the cosmological constant.
To Einstein this extra term, lambda, the cosmological constant,
spoilt the beauty of his original equation.
But he could see no other way to make the Universe stable.
Now this is a constant that gives space-time itself
the property that it would tend to spontaneously expand,
and so he added that constant in just the right amount
that this property of space-time to expand would exactly balance
the property of the matter in the galaxy or in the Universe to collapse under its own gravity.
So by exactly balancing these two, he could therefore make the Universe stable.
Now it wouldn't really have worked of course because it's the stability of a pencil on its point.
Even the smallest deviation - too small a matter of density, too large amount of density
would have made the Universe collapse or expand,
so I don't really think he'd solved the problem.
Einstein's problem was that, according to his theory, the Universe was inherently unstable;
it should have collapsed or exploded long ago.
It's a mystery that worries scientists to this day.
This is the echo of creation.
Detune a television set and it will pick up microwave radiation
from the edge of the visible Universe.
When it' set out on its journey, it was orange light
but over the 15 billion years it has been travelling the Universe itself, has grown a thousandfold,
stretching the light so that we now see it as microwaves.
It warms us as it warms the entire cosmos,
raising the temperature of space by 3 degrees.
This signal is powerful evidence that the Universe is not unchanging as Einstein imagined
but that everything we see around us was once part of an immense fireball.
The first hints of that fiery beginning were found when astronomers started to look out into space
beyond our own galaxy.
The 1920s was an exciting time in astronomy
because that's when the first large telescopes came on line
and Edwin Hubble, an American astronomer,
started looking at nearby stellar systems which we now call galaxies.
Dr Edwin Hubble on a moveable platform
lines up the massive telescope as he begins a cold night's work.
And to his astonishment he found that they were very, very far away firstly,
and secondly by measuring the light from these galaxies,
he was able to see that they were moving away from us.
To Hubble this could only mean one thing: the Universe itself must be expanding.
It's a pretty profound discovery that the Universe is expanding
because if you think about it what that means is that
at some point in the past, things were closer together.
So if you measured density - the number of galaxies in a little box of space
- then as you go back in time, the number that fit in a fixed box of space goes up
and so the Universe becomes much denser and hotter.
As one goes back in time, eventually you will come to a point which we call the Big Bang
when the density was extremely high.
And so the profundity of this discovery is that the Universe had a beginning: a Big Bang.
If Hubble was right and the Universe had started with a cosmic explosion,
then the force of this alone might be enough
to counterbalance gravity's tendency to make the Universe collapse and die.
Perhaps here was a way to make the Universe stable and solve Einstein's problem.
You would have thought Einstein would respond positively to observations,
but as is often the case, theorists completely ignore observations
and so here was Hubble with a fantastic discovery - probably discovery of the century -
and Einstein really didn't take any notice of it.
So Einstein stuck to his static Universe,
insisted on his cosmological constant to keep the Universe static,
and it wasn't really until a meeting here in California between Hubble and Einstein in about 1932
that really there was a synergy between Einstein and the expanding Universe.
And here he comes, down from the sun tower after a hard morning,
looking a few million miles into his favourite space.
Hubble, in the middle here, soon convinced Einstein that the Universe was indeed expanding.
The cosmological constant which Einstein had introduced
to hold up a static Universe against the force of gravity
appeared to be unnecessary after all.
With relief Einstein returned to the original form of his general theory of relativity.
And it's at that time, or shortly after that, Einstein said
that the invention of this cosmological constant
was his biggest blunder.
The construction is very, was very skilful.
You had to build up the outside and then put in the inside and then more outside
and inside it was a great piece of engineering.
But Einstein's optimism was premature.
It has gradually dawned on cosmologists
that the Big Bang doesn't in fact solve the problem with the Universe's stability.
For 21st-century physicists like Joao Magueijo and Andy Albrecht,
the cutting edge of research is still the problem first identified by Einstein back in 1916.
If we can really make that connection,
then it's the reason why people should want the speed of light to vary.
You'd think, with all the great success of the Big Bang, we'd be happy,
we wouldn't be complaining - we are, we're concerned.
There's a problem with the Big Bang,
and the problem is we shouldn't be here.
The Universe has been gently expanding for 15 billion years.
That's allowed time for stars, planets and cosmologists to evolve.
The problem is, it's almost impossible to get a gently expanding Universe out of the Big Bang.
Either it expands too fast or it falls back in on itself.
Either way the Universe could not last very long.
A good analogy is to think about throwing a rock in the air.
You throw it up; you expect it to come back after a little while.
You throw a little bit harder and it goes further; but eventually comes back.
If you throw it hard enough - and no human can do this but NASA can do it with a space ship
- you can leave the gravitational attraction of the Earth
and fly off forever.
With the Universe there's this delicate balance.
You throw the rock in the air - it keeps going. Is it gonna turn around?
You don't know, it keeps going, it keeps going, you don't see it flying off,
you don't see it turning around, it's balanced right at the edge for year after year,
thousands of years, billions of years.
We're now at almost 15 billion years, we still don't know - is it coming back, is it flying off?
That's what the Universe is like.
With the ball it's how fast you throw it.
With the Universe the key thing is the amount of matter and energy in the Big Bang.
To produce gentle expansion, the density of this energy has to be precisely right.
How do we start this Universe out in such a special state?
We have to take a number that describes the density of the matter in the Universe
and get it right to a hundred decimal places, one after the other.
If we get one decimal place wrong the whole thing gets out of whack.
No physicist can stomach setting up a Universe in such a delicate way.
Yet something set up the Universe in the right way.
Some mysterious process made sure that matter and energy
had everywhere the same critical density
keeping the entire cosmos in perfect balance.
Scientists call this the flatness problem.
So this is the flatness problem: it's the fact that the Universe is a bit like a pencil
standing on its stick for 15 billion years.
And it's even worse than that.
The puzzle is that when you start saying OK, suppose at the beginning
things were different and something could come along
and adjust everything just the way you need it,
you run into the following problem:
nothing can travel faster than the speed of light.
The Universe is very, very big.
Bigger than we can imagine and bigger than we can see.
There are regions of space so far away they are invisible
because the light from them has not yet had time to reach us.
In effect we are surrounded by a horizon;
this horizon has been growing at the speed of light since the Universe began
but beyond it are regions with which we have never had any kind of contact.
Since nothing, not energy nor any kind of physical process can travel faster than light,
nothing can cross the horizon.
The Universe is now 15 billion years old
which means that the horizon is actually very large nowadays.
It's about 30 billion light years across.
This doesn't mean that the Universe is only this size; of course the Universe is infinite.
It just means the region we can see is this 30 billion light year region,
and when the Universe is very young conversely,
it's still very big but conversely you see a smaller and smaller fraction
because the horizon is smaller and smaller.
To see what this means, imagine that we could travel back in time.
We would see the Universe shrinking rather than expanding,
but our view of it would shrink even faster
because our horizon would be shrinking at the fastest possible speed: the speed of light.
Galaxies that are visible today would have been invisible to us in the past,
and to each other.
So the early Universe was divided up into small islands, isolated inside their own small horizons.
This picture of a disconnected Universe
flies directly in the face of the idea of a single balancing process
needed to solve the flatness problem.
Confused? So were the cosmologists.
The only way round this horizon problem was to assume that the entire region we see today
started out so tiny it could fit inside a single horizon.
This idea, called inflation, was first proposed by Alan Guth
and then developed by Paul Steinhardt and his colleague Andy Albrecht.
Today, their version of inflation is widely accepted among scientists
but Andy Albrecht himself has never been wholly convinced by his own theory.
What we have to do to make inflation work is invent an entirely new form of matter
that exists in the early Universe and then disappears so we don't have it around today.
And I was always left with the nagging feeling that if you invent so much,
is inflation really the right thing to invent?
Or could nature have chosen something else?
As a young researcher at Cambridge in the mid-1990s,
Joao Magueijo was also sceptical about inflation.
Because inflation is the only thing available, people cling to it, just like to a lifeboat.
But some people need that - that's great.
To be a bit extreme, you could say, you could solve all these fine-tuning problems
using divine intervention and I think inflation is a scientifically acceptable way
to invoke divine intervention at some point.
That's a bit over the top but there's enough open questions that we really need to think about it.
One day Joao saw that there might be a much simpler way to solve the horizon problem.
One winter morning, like this one, walking around these fields
I just realised that if you were to break one single but sacred rule of the game,
the constancy of the speed of light,
you could actually solve the horizon problem.
And when you think back on it, it's just such an obvious thing,
that when the Universe is very young,
if the light was very fast you could actually have a very large horizon.
When the Universe was one year old the horizon would be one quick light here across,
which could be as big as you wanted
and of course you connect the whole of the Universe if you do this.
If early light was much faster,
a single horizon could be big enough to encompass the entire known Universe.
It was a bold idea, too bold.
This came at the time when I was a fellow of this college
but it was also a stage in my career where I had to look for a job.
I was about to finish my position here.
This is not the time to go and pursue a very original idea.
I was already quite controversial at the time.
I didn't need another thing that would be even more controversial.
There were times when I saw myself selling the Big Issue outside St John's College!
So I waited until I was on much safer ground.
Joao found that safer ground when the Royal Society awarded him
a rare and prestigious research fellowship.
He joined Andy Albrecht's group at Imperial College.
They started to work on Joao's idea together.
One day Andy just called me to his office and he said,
'Joao let's work on the varying speed of light too,'
and he closed the door and made a big secret about it.
He erased the blackboard afterwards; he was really afraid someone might steal the idea.
And then gradually we just started putting more and more maths together,
to try and find more and more things about the theory.
You face the frontier, you face unknown questions
and you argue about it and you have competing ideas and,
after a while one is clearly the winner.
And you're really worried about something,
it really is with you all the time, not just in your office.
You go through phases in which you dream about your ideas, you sleep over your ideas
you wake up tired.
Well you need to cast things into equations in the end
because this is what science is all about.
It's about mathematical models not just pictures, otherwise it's all very cranky.
I think there is a very unique aspect of scientific discovery,
there is a big adrenaline rush when you've spent months and months
struggling with the problem getting it wrong
and eventually you discover something and it's unique.
I'm addicted to adrenaline in general but this one is unique.
And I think this is the reason why scientists tend to be such big nerds
because social interaction, for instance, doesn't match quite this kind of pleasure.
which scientific discovery can give.
Joao and Andy were creating a completely new physics.
As they explored this strange new world it began to dawn
that perhaps they could solve more than just the horizon problem.
We got more than what we bargained for
and this is really where the thing was massively rewarding.
We found that we could solve the flatness problem as well
and the reason for that is we realised very quickly
there's no way we have energy conservation if the speed of light varies.
In conventional physics, energy is conserved.
It can be transformed but it cannot be created or destroyed.
This is the principle of the conservation of energy
and it means that the total amount of energy in the Universe is fixed.
So the critical energy density the Universe needs
must be established perfectly, right from the beginning.
Now if we change something as fundamental as the speed of light,
which is woven into the whole fabric of physics
then of course you're breaking that principle: the Universe is different at different times.
And you don't conserve energy.
But then you realise this is exactly what you need to solve the flatness problem
because you violate energy conservation pushing the Universe to the critical energy density.
That is, you create energy if you have sub-critical energy density and vice versa.
You take away energy if you have a surplus of energy density.
In their theory, during the early Universe the speed of light was falling,
which allowed the cosmos a built-in thermostat,
creating or destroying energy so that the critical density was maintained exactly.
Thus the Universe remained in balance for billions of years.
We were just trying to find an alternative to inflation
as far as the horizon problem was concerned.
We actually did not have hopes of solving everything.
This was a gift we got out of it.
Joao and Andy had set out to solve the horizon problem
and stumbled upon a theory that solved the puzzle
which had plagued cosmology since the time of Einstein.
They had made a Universe that was inherently stable,
held in balance by the creation or destruction of energy.
A theory which predicted the Universe as we see it today.
However it was still just a theory;
proof could only come from the depths of space-time.
But what astronomers found there would astonish everyone.
Suggesting that the speed of light was also the key to the biggest mystery in cosmology:
what happened before the Big Bang.
Long ago when the Universe was young,
light itself travelled faster than it does today.
The laws of physics were very different; that at least was the theory.
The evidence could only come from the world's great telescopes.
As they scan the far depths of space, astronomers also look back in time.
In 1998 the British astronomer John Webb
started to become interested in the question
of whether the fundamental constants of nature could change
as the Universe evolves.
We're using a technique which enables us to look back into the past
to measure physics as it was a long time ago.
So we're doing that using quasars.
Quasars are the most distant objects we can see;
they are thought to be primitive galaxies in the process of formation.
But John Webb is not interested in the quasars themselves.
Quasars are just, as far as we're concerned for this study,
very distant sources of light which shine through the Universe to us.
In doing so, they intersect gas clouds along the line of sight
and then we can study the physics of those gas clouds
by looking at the way in which the light is absorbed.
We can look at gas clouds relatively nearby,
and we can look at them just about as far away as the most distant quasars.
That means in terms of 'look back' time almost 10 billion years,
or something like that, an awful long time ago.
So we're studying physics as it was when the Universe was quite young.
When light passes through an interstellar gas cloud
it collides with the electrons and the gas molecules.
This creates a pattern of dark lines in its spectrum.
What John Webb noticed was that this pattern looked different
in the spectra from the most distant clouds.
The inference was astonishing:
either the electrons were different or the speed of light was greater in the distant past.
If it's correct, it's certainly a very profound result for physics
because it would be the first ever indication that the laws of nature
were not always the same as they are today.
But far off in space and time an even more amazing discovery was waiting for astronomers:
today cosmology is buzzing with news of the unexpected comeback
of an idea discarded 70 years ago.
Einstein's cosmological constant, lambda.
For Joao it means taking his theory even further.
He now believes the cosmological constant
could be the link that connects changes in the speed of light
to the origin of the Universe itself.
So Einstein has already endowed space-time with its own life,
when he allowed space-time to curve,
to have its own dynamics, and the cosmological constant was one step further
because it was basically giving space-time its own energy
so that even before he put matter into space-time, when we have vacuum,
you have some energy density in this vacuum
and this is what lambda is, and it has this very interesting property
that essentially it makes repulsive gravity.
Lambda produces gravity that pushes things apart rather than pulling them together
and that seems to be what's happening to the Universe,
something is blowing it apart.
Ever since Hubble convinced Einstein that the Universe is growing,
astronomers have been trying to measure its rate of expansion.
The breakthrough came when they started to concentrate on exploding stars called supernovae.
They thought that these would allow them to chart the gentle deceleration of the Universe.
What they actually found was precisely the reverse.
Now the question is, is the Universe slowing down as we would expect?
The surprise is that instead of the Universe slowing down, in fact it's speeding up.
Something is upsetting the delicate balance of the Universe,
pushing the galaxies apart faster and faster.
A new force in the vacuum of space.
The acceleration as seen from the supernova data, of course,
raises the amazing question of resurrecting Einstein's cosmological constant.
It looks as if space-time is humming with energy.
Buried in the equations of this theory,
Joao has found a hidden link between this energy and the speed of light.
Well at some point we've found out two interesting things.
One was that the energy in the cosmological constant also depends on the speed of light,
and in particular if the speed of light drops, then the energy in the vacuum drops as well.
And the second thing we've found is that this cosmological constant itself
promotes changes in the speed of light - it can make it drop in value.
So we have an instability.
In Joao's theory, a change in the vacuum can cause a drop in the speed of light,
but this in turn reduces the amount of energy the vacuum can hold,
forcing energy out of it and into ordinary matter and radiation.
Could this be the genesis of the Universe?
What happened before the Big Bang?
So in some of these scenarios in the beginning there is just a vacuum -
but the vacuum is not nothing, it's actually the cosmological constant,
this pull of energy in the vacuum.
And in these theories, it is this energy that drives changes in the speed of light;
it makes a drop in value.
And what that does is that makes all the energy in the cosmological constant drop as well.
It has to go somewhere. Where does it go?
It goes into all the matter of the Universe, so it caused a Big Bang.
So in this scenario it's actually this sudden drop in the speed of light -
this change in the speed of light - what causes the Big Bang.
In the beginning was the void.
But the void was not nothing
and there was light and the light changed.
And so the void brought forth the world
and the world was good, for it endured until men could comprehend it.
But it will come to pass that one day the energy of the void will have pushed all things away,
leaving nothing but the void.
But the void is not nothing.
And you might think this is the end of the Universe,
but of course in the picture of this theory
it's just creating the conditions for another Big Bang to happen again
A sudden drop in the speed of light,
another sudden discharge of all this energy into another Big Bang.
So it is possible that actually our Big Bang is just one of many, one of many yet to come basically,
and one of many which there were in the past already -
maybe the Universe is just this sequence of Big Bangs all the time.
Joao's bold challenge to the constancy of the speed of light
has led him to a wholly new view of the cosmos.
One in which the Universe no longer has a beginning and an end, but is eternal.
An endless cycle of Big Bangs drawn from the vast reservoir of energy in the vacuum.
And like every cosmologist before him, Joao has been guided by the theory that started it all:
it is a measure of Einstein's genius that even when he was wrong, somehow he was right.
What he called his biggest blunder may yet prove his greatest legacy.
Well of course I respect relativity enormously and I have this feeling
that it is only now that I have contradicted relativity that I really understand it.
And it's actually just because I've gone against it that I'm showing my full respect to the great man.
This is not at all trying to contradict Einstein or anything,
it's just trying to take things one step further.
Eventually of course it will be nature that will decide whether this is true or not.
I'm working on basically trying to find ways of deciding whether the theory is right or wrong.
Some kind of experiment which will decide conclusively whether
the varying speed of light theory is pure nonsense or not.
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