Hello. My name is Stephen Hawking.
Physicist,cosmologist,and something of a dreamer.
Although I can not move and I have to speak through a computer...
In my mind,I am free.
Free to explore the most profound mysteries of the cosmos.
Such as: Why is the universe the way it is?
Why does it follow rules and laws?
Why is there order instead of chaos?
Finding out leads us to the very deepest of secrets.
To the one principle that sit the heart of everything in the cosmos.
Check it out.
The Aurora Australis or Southern Lights seen from the International Space Station.
I've devoted my life to the search for an explanation to such...
beautiful mysteries.
Because I believe it would lead us to the secrets of the universe itself.
This is the search for one I call the Grand Design:
The key to the cosmos.
The good news is,I think we found it.
Almost.
Getting here has been quite a journey.
It began one night 350 years ago...
In the small English town of Cambridge.
The year was 1665.
Death stroke the land as England fell under the plagues,dark spell.
A student called Isaac Newton,fled out...
To escape the threat.
We fortunately got away,because Newton was a radical thinker...
who dare to see the universe in a completely new way.
Newton took the first steps in the search for the Grand Design
by looking for the mysterious laws that govern nature.
He asked,"Why the things move?" "Why do they stop?"
and most famously: "Why do they fall to earth?"
You might not think answer to such simple questions would change the world...
But it did.
Because Newton realize there was a force outwork deep within the fabrique of the universe...
that makes all objects attract one another: the force of gravity.
Gravity works not just on Earth but throughout the cosmos.
And its strength depends on just a couple of fundamental things:
The mass of the objects and their distance apart.
To find these answers,Newton invented a completely new mathematical language,called...
The calculus.
You don't need to know how it works,but it wasn't bad...
for a 23 year old.
Scientists all over the world still use it every day.
Newton's work,made it possible to predict everything...
from the orbits of planets around the stars...
and the precise timing of eclipses...
to the trajectories of raindrops.
Today,we theoretical physicists are still doing the same sort of things as Newton.
And thankfully we don't have to worry about the plague.
Although our work may seem complex,it's really quite simple.
We're trying to unravel the hidden mechanism...
that underlies everything.
We can only do it just because we stand on the shoulders of giants.
Scientists who piece by piece discovered what makes...
the universe take.
Amongst those giants was another of my scientific heroes:
James Clerk Maxwell.
Maxwell was fascinated by light...
which in 1861 led to him inventing color photography.
But that was just the beginning of what this remarkable man achieved.
It was when he began to investigate a completely different round of physics...
that everything changed.
This was the strange,almost magical connection...
between magnetism and electricity.
There is nothing complicated about it.
Move a magnet near a wire...
and you will cause electricity to flow through the wire.
Put electricity through a wire,and it would act like a magnet...
and deflect the compass.
So what connected them?
Maxwell's big idea was that magnetism and electricity...
are actually two facets of the same thing:
a wave of energy that was part electrical part magnetical.
He called them: electromagnetic waves.
But then came a surprise.
The mathematics told him this electromagnetic waves...
travel at extraordinary speed: 186,000 miles per second.
The exact same speed that had already been determined to be the speed of light.
This led to astounding conclusion:
Light is an electromagnetic wave,too.
Maxwell connected electricity,magnetism,and light...
in a series of four equations...
that I consider to be one of the greatest discoveries...
in the history of science.
The equations called Maxwell's laws...
govern everything from the auroras that dawn over the north and south poles...
to the modern electrical and communications technology...
that powers the planet.
Virtually every machine in the modern world...
from the computer to a power station to a washing machine...
works to the rules Maxwell reviewed.
Electromagnetism quite literally lights up our planet.
A fitting testament to a great mind.
But light is much more interesting than is Maxwell himself realized.
Although he didn't know it,
he had actually uncovered one of the fundamental clues of the Grand Design.
That clue is the speed of light itself.
By the late nineteenth century it looked like...
some of the great mysteries of the universe would be all wrapped up...
thanks to the groundbreaking discoveries of Newton and Maxwell.
But then two American physicists stumbled into a completely unexpected discovery.
Albert Michelson and Edward Morley were investigating...
the implications of Maxwell's revelation that light is a form of wave...
traveling at 186,000 miles per second.
They figured that just as water waves,a wave of energy traveling in water...
and sound waves,a wave of energy traveling through air...
so light waves must also travel through... something.
They called this "something": the luminiferous ether.
Michelson and Morley proposed that space...
including the space between the sun and the earth...
Was filled with this mysterious ether.
They believed that sunlight must travel through the ether...
to reach earth.
Since the earth also move around the sun...
They must be traveling through this ether,too.
If so,this movement would cause what they called an 'ether wind'...
to blow over the surface of our planet.
Michelson and Morley believed this ether wind should be detectable here on Earth...
and design an experiment to measure its effects.
They ran their experiment in a crowded basement.
But to understand the principle behind it...
I thought we get them out of the lab and stay out here on the beach.
Since the earth is constantly orbiting the sun...
then the ether wind would be ever-present...
and would effect the speed of light here,on earth.
If a beam of light was traveling with the ether wind behind them...
the light should move faster.
But if light was traveling in the exact opposite direction,