0:00:03 > 0:00:05There are some great questions
0:00:05 > 0:00:11that have intrigued and haunted us since the dawn of humanity.
0:00:30 > 0:00:36The story of our search to answer those questions is the story of science.
0:00:38 > 0:00:43Of all human endeavours, science has had the greatest impact on our lives,
0:00:43 > 0:00:46on how we see the world, on how we see ourselves.
0:00:47 > 0:00:52Its ideas, its achievements, its results, are all around us.
0:00:53 > 0:00:58So, how did we arrive at the modern world?
0:00:58 > 0:01:02Well, that is more surprising and more human than you might think.
0:01:07 > 0:01:12The history of science is often told as a series of eureka moments.
0:01:12 > 0:01:14The ultimate triumph of the rational mind.
0:01:14 > 0:01:17But the truth is that power and passion,
0:01:17 > 0:01:20rivalry and sheer blind chance
0:01:20 > 0:01:23have played equally significant parts.
0:01:25 > 0:01:31In this series, I'll be offering a different view of how science happens.
0:01:32 > 0:01:35'It's been shaped as much by what's outside the laboratory as inside.'
0:01:35 > 0:01:37Whoa!
0:01:39 > 0:01:41This is the story of how history made science,
0:01:41 > 0:01:43and science made history,
0:01:43 > 0:01:47and how the ideas that were generated changed our world.
0:01:49 > 0:01:53It is a tale of...
0:01:54 > 0:01:58..and
0:02:06 > 0:02:10This time, one of the oldest questions we've asked:
0:02:30 > 0:02:35These days, you have to drive a long way to go and see the night sky the way that our ancestors did.
0:02:35 > 0:02:40One of science's great achievements was to create artificial light.
0:02:40 > 0:02:44But unfortunately it does tend to blot out the beauty of the cosmos.
0:02:55 > 0:02:59It's very peaceful and quiet here, which is rather surprising
0:02:59 > 0:03:01because you and I are actually on a giant rock,
0:03:01 > 0:03:06which is spinning through empty space at at least 1,000 miles an hour.
0:03:06 > 0:03:08And with our companion, the moon,
0:03:08 > 0:03:11we are also hurtling round the sun
0:03:11 > 0:03:14at a terrifying 67,000 miles an hour.
0:03:14 > 0:03:17And that's not all,
0:03:17 > 0:03:23because we are part of a huge galaxy called the Milky Way, which consists of hundreds of billions of stars.
0:03:28 > 0:03:31Out there, we have seen the birth and death of stars,
0:03:31 > 0:03:35heard the whisper of creation.
0:03:35 > 0:03:41We now realise our universe is a place of unimaginable strangeness.
0:03:42 > 0:03:48It is so hard to understand that it's not surprising that, for most of history,
0:03:48 > 0:03:51there was a very different view of what is out there.
0:03:54 > 0:04:00This is the story of how we came to know what we do know about this bizarre and dazzling universe.
0:04:06 > 0:04:08For me, the story begins in Prague,
0:04:08 > 0:04:11in the opening days of the 17th century,
0:04:11 > 0:04:14a defining moment in the creation of modern science.
0:04:18 > 0:04:22It was here that three critical factors came together.
0:04:22 > 0:04:24Men with daring ideas.
0:04:24 > 0:04:26Collectors of evidence.
0:04:26 > 0:04:29And someone prepared to pay for it all.
0:04:30 > 0:04:32Europe was in turmoil.
0:04:32 > 0:04:36Forces of religious and political change were sweeping across the continent.
0:04:36 > 0:04:39These were violent and dangerous times.
0:04:39 > 0:04:44But, out of all this tumult would emerge a new vision of the cosmos.
0:04:44 > 0:04:48It all started when a couple of the age's more unusual thinkers
0:04:48 > 0:04:53came to work at the court of the Holy Roman Emperor, Rudolph II.
0:04:55 > 0:05:01In those days, Prague was a major centre of power and culture.
0:05:01 > 0:05:04The Emperor Rudolph was hungry for new discoveries.
0:05:06 > 0:05:11New ideas to dazzle and impress his fellow rulers.
0:05:14 > 0:05:18His enormous wealth and patronage drew to Prague one of the
0:05:18 > 0:05:23brightest stars of the age, the astronomer Tycho Brahe,
0:05:23 > 0:05:27an eccentric Danish nobleman.
0:05:27 > 0:05:31Tycho was a wonderfully colourful character.
0:05:31 > 0:05:35When he was a student, he lost a large chunk of his nose in a duel
0:05:35 > 0:05:38and had it replaced with a metal one.
0:05:38 > 0:05:44Legend has it he kept a dwarf under his table, and he believed that that dwarf was clairvoyant.
0:05:44 > 0:05:50He also apparently kept an elk, which fell down the stairs when drunk, and died.
0:05:50 > 0:05:55There is however one thing about Tycho which is absolutely certain - he was a passionate stargazer.
0:06:04 > 0:06:10Science needs evidence, and Tycho was a new sort of data gatherer.
0:06:12 > 0:06:18He built a vast observatory, and equipped it with the best instruments money could buy.
0:06:22 > 0:06:28And so was his commitment, night after night for over 20 years.
0:06:28 > 0:06:32He was putting together a unique body of evidence
0:06:32 > 0:06:36that would in time reveal the secrets of how the planets move.
0:06:38 > 0:06:41Right. So we've got the moon over there.
0:06:41 > 0:06:46Now this is how you'd make an observation with Tycho's Quadrant.
0:06:46 > 0:06:48It is of course pointing at the moon.
0:06:48 > 0:06:50You take the sighting arm.
0:06:50 > 0:06:53You sight it exactly upon the moon.
0:06:53 > 0:06:59- You would look through the upper slit across the upper part of that central brass peg...- Yeah.
0:06:59 > 0:07:01Then the lower slit through the lower peg,
0:07:01 > 0:07:03so the upper and the lower cusps of the moon,
0:07:03 > 0:07:06the points of the moon, were between them.
0:07:06 > 0:07:07You've got it lined up, essentially.
0:07:07 > 0:07:09Absolutely lined up.
0:07:09 > 0:07:13OK. So I get that as 15 degrees...
0:07:13 > 0:07:17- and 40 minutes of arc.- That sounds perfectly reasonable.- OK.
0:07:17 > 0:07:24- And that is logged as the moon, on the 26th of May at just past ten o'clock.- Just past ten o'clock.
0:07:24 > 0:07:27So he would go on plotting these details throughout the night.
0:07:27 > 0:07:30Yes. Not just the moon, the moon would set, but you'd do it for planets,
0:07:30 > 0:07:35as things appropriately came in the sky, and build up these great observing logs of raw data.
0:07:35 > 0:07:39And out of that, of course, is what the heart of science is.
0:07:39 > 0:07:44Tycho starts his tradition of science, not just being about information and theories, about data.
0:07:44 > 0:07:47Information and analysis from fresh observations.
0:07:47 > 0:07:50- Books of it, presumably? - Absolutely.
0:07:50 > 0:07:55Having seen you in action now, what I'd like to do now is look at a star, the pole star, the north star.
0:07:55 > 0:07:59The pole star, which of course everything rotates around, the star over here.
0:08:01 > 0:08:05What Tycho was doing represents something really important
0:08:05 > 0:08:08in the emergence of science -
0:08:08 > 0:08:12a commitment to cold, hard, obstinate facts.
0:08:12 > 0:08:17I can see it now I'm lining it up with that and...
0:08:17 > 0:08:22That is 51 degrees and 36 arc minutes.
0:08:22 > 0:08:26- Right, excellent. So that's my first star.- It is indeed. Not bad at all.
0:08:26 > 0:08:28Thank you. I've got 776 to go.
0:08:28 > 0:08:31- Congratulations!- Thank you. - THEY LAUGH
0:08:35 > 0:08:39It's a shame that the craftsmen who built such beautiful instruments,
0:08:39 > 0:08:42and men like Tycho who used them,
0:08:42 > 0:08:43get so little credit.
0:08:45 > 0:08:48Because the evidence that he gathered would, in time,
0:08:48 > 0:08:54undermine a belief system that had dominated Western thought for over 2,000 years.
0:09:10 > 0:09:15Many early civilisations developed sophisticated ideas about the heavens.
0:09:19 > 0:09:23But the Western view was, above all, defined in ancient Greece.
0:09:30 > 0:09:34You can get a sense of Greek cosmology if you come here.
0:09:34 > 0:09:36This is the sacred site of Delphi.
0:09:36 > 0:09:41Its famous oracle drew people from all over the Greek world.
0:09:44 > 0:09:51This is the Temple of Apollo, and it's where you'd have come and often received extremely cryptic advice.
0:09:51 > 0:09:55It is also where you would have found the Omphalos, a stone which
0:09:55 > 0:09:59marked the centre of the world, and therefore for many Greeks, the centre of the cosmos.
0:10:02 > 0:10:06Down the centuries, Greek philosophers argued long and hard
0:10:06 > 0:10:09about the shape of the universe and what is out there
0:10:09 > 0:10:14until, in the end, one particular view became dominant.
0:10:16 > 0:10:22Around the fourth century BC, a number of Greeks developed a model of the universe in which the Earth
0:10:22 > 0:10:28was stationary and everything else moved in giant, perfect circles around the stationary Earth.
0:10:30 > 0:10:33The perfect circular orbits of the other planets
0:10:33 > 0:10:37reflecting the perfection of the gods that had put them there.
0:10:37 > 0:10:41It was simple, intuitive and, of course, it was wrong.
0:10:41 > 0:10:43Yet it endured.
0:10:45 > 0:10:49So why did this idea persist for so long?
0:10:49 > 0:10:53Well, it's partly because it's comforting to be at the centre of things.
0:10:53 > 0:10:57But also because the alternative made absolutely no sense.
0:10:57 > 0:11:00If we really are on a rock hurtling through space,
0:11:00 > 0:11:04then surely we would be constantly buffeted by huge winds.
0:11:08 > 0:11:15So, commonsense said the Earth must be stationary with everything going round it.
0:11:15 > 0:11:20But there was a problem with this idea, a pretty fundamental one.
0:11:29 > 0:11:32A remarkable discovery, made just over a century ago,
0:11:32 > 0:11:36gives us a striking insight into the Greek view of the cosmos.
0:11:41 > 0:11:44It was the result of a freak storm.
0:11:52 > 0:12:00Battered by strong winds, a group of sponge divers took shelter on the small Greek island of Antikythera.
0:12:03 > 0:12:10When the storm finally subsided, one of the divers decided to explore the unfamiliar waters.
0:12:15 > 0:12:21There were no sponges, but strewn across the seabed were the remains of an ancient shipwreck.
0:12:24 > 0:12:28Its cargo 2,000 years old.
0:12:31 > 0:12:37They also found a strange bronze mechanism, which would turn out to be one of the rarest and,
0:12:37 > 0:12:42in its own way, most precious treasures ever recovered from the ancient world.
0:12:45 > 0:12:52It is a beautifully engineered scientific instrument, with wheels and cogs carved from bronze.
0:12:56 > 0:13:00Nothing like this would be made for another thousand years.
0:13:03 > 0:13:06But its exact purpose has long been a puzzle.
0:13:11 > 0:13:14Michael Wright has spent more than 20 years attempting to
0:13:14 > 0:13:17create a model of the original, and to understand its workings.
0:13:19 > 0:13:22- Hello.- Hello.- Nice to meet you. And this is the mechanism, is it?
0:13:22 > 0:13:25- This is the mechanism. - Do you mind if I twiddle?
0:13:25 > 0:13:27Of course, have a go. You won't break it.
0:13:28 > 0:13:29So what's it doing when I turn this?
0:13:29 > 0:13:33This is the representation of the sky as
0:13:33 > 0:13:35people tended to think of it.
0:13:35 > 0:13:37You can picture, if you like,
0:13:37 > 0:13:40the Earth being at the centre of the dial,
0:13:40 > 0:13:44and the planets and the sun and moon going round us.
0:13:44 > 0:13:46- That's the moon there. - That's the moon.
0:13:46 > 0:13:49And as the moon goes round, that's presumably what, full moon?
0:13:49 > 0:13:52That's full moon because it's opposite the sun pointer.
0:13:52 > 0:13:56- What impresses me is, so somebody designed this well over 2,000 years ago.- Yes.
0:13:56 > 0:13:58Built it well over 2,000 years ago.
0:13:58 > 0:14:01Of course, the bit you're looking at here is my restoration.
0:14:01 > 0:14:06So, I don't guarantee the original was exactly like this, but I do say
0:14:06 > 0:14:09with some confidence it was along these lines.
0:14:09 > 0:14:12That is very clever!
0:14:14 > 0:14:21But what this mechanism illustrates is how the Greeks wrestled with a tricky astronomical problem.
0:14:21 > 0:14:26One that comes about if you think that the Earth is at the centre of the universe.
0:14:26 > 0:14:27It's this.
0:14:29 > 0:14:34The planets sometimes appear to move backwards in the night sky.
0:14:37 > 0:14:41It's a problem that the Greeks recognised and agonised over.
0:14:47 > 0:14:50Most of the time, they're going forwards,
0:14:50 > 0:14:54which is sort of what I would expect, some of them going fast.
0:14:54 > 0:14:58- Ooh and that one's... Which one's that?- Oh, that's Mars. - Now we see it's stopped.
0:14:58 > 0:15:00And there it goes backwards.
0:15:00 > 0:15:03- All the planets have these phases of going backwards.- Right.
0:15:03 > 0:15:07But Mars has a particularly bold one.
0:15:07 > 0:15:11In general, you see them moving a little further east every night.
0:15:11 > 0:15:14But there come times with each of the planets when they seem to stop
0:15:14 > 0:15:18amongst the stars and go westward, for a, a period of days.
0:15:18 > 0:15:20And then they stop again and go back eastward.
0:15:20 > 0:15:24And this instrument replicates that behaviour.
0:15:30 > 0:15:35This complexity didn't make the Greeks question their perfect circles.
0:15:35 > 0:15:41Instead, they added more, a lot more - well over 50.
0:15:41 > 0:15:45This tangle of circles moving upon circles explained how the planets
0:15:45 > 0:15:47appeared to move backwards,
0:15:47 > 0:15:50and preserved the belief in an Earth-centred universe.
0:15:55 > 0:15:58The person who made this knew the latest astronomy,
0:15:58 > 0:16:04he knew how to combine circular motions to get something like the true motion of the planets.
0:16:11 > 0:16:17This view of the cosmos was one of the most enduring beliefs in human history.
0:16:18 > 0:16:22It took root in the Arab world after the collapse of Rome.
0:16:24 > 0:16:27And it was adopted by the Catholic Church in Europe.
0:16:31 > 0:16:37It was so deeply embedded in European thought that it would take a radical shift to dislodge it,
0:16:37 > 0:16:42and that was brought about by a great force of history.
0:16:45 > 0:16:47The Reformation.
0:16:48 > 0:16:52It began as a revolt against abuses by the Catholic Church.
0:16:56 > 0:17:01And ended splitting Western Europe into two, Catholic and Protestant.
0:17:03 > 0:17:10The new Protestant movement stressed the role of the individual outside the authority of the Church.
0:17:15 > 0:17:19The Reformation created two conflicting views about
0:17:19 > 0:17:22the route to personal salvation, about how you got to heaven.
0:17:24 > 0:17:28If there could be doubt about such a fundamental question,
0:17:28 > 0:17:31then perhaps there were also doubts about other ancient truths.
0:17:31 > 0:17:34The Reformation created an intellectual climate
0:17:34 > 0:17:37in which it became possible to question authority.
0:17:45 > 0:17:49And, critically for the question, what is out there, the wars and violence that
0:17:49 > 0:17:54followed the Reformation brought a rather special refugee to Prague.
0:17:55 > 0:18:01Arriving to join Tycho the stargazer was an impoverished German mathematician, Johannes Kepler.
0:18:05 > 0:18:11When Johannes Kepler arrived here in Prague in 1600, he was in dire straits.
0:18:11 > 0:18:16His two young children had recently died, and he was in desperate need of a job.
0:18:23 > 0:18:27When he arrived here, there was no procession, there was no imperial greeting.
0:18:27 > 0:18:35I am reasonably sure that amongst his possessions however he would have had one of these horoscopes.
0:18:35 > 0:18:42Ironically enough, a man who would be greeted as one of the greats of science practised astrology.
0:18:45 > 0:18:49Kepler had come to Prague to work for Tycho.
0:18:50 > 0:18:54But, soon after he arrived, Tycho died.
0:18:54 > 0:19:00While the court mourned, Kepler purloined Tycho's vast collection of star data.
0:19:04 > 0:19:09Kepler was now the court mathematician AND Rudolph's main astrologer.
0:19:12 > 0:19:16To us, this might seem an odd combination of roles.
0:19:18 > 0:19:24But back then, great rulers often had an astrologer, someone like Johannes Kepler,
0:19:24 > 0:19:28to cast their horoscopes to peer into the future.
0:19:32 > 0:19:36Astrology was all about predicting where and how the planets would move.
0:19:38 > 0:19:42It depended on accurate star charts and good mathematics.
0:19:48 > 0:19:52We still use astrological language when we talk about lunatics,
0:19:52 > 0:19:56people who've been driven mad by "lunar", the moon.
0:19:56 > 0:20:01Or disasters, terrible things that happen to us because of "astra", the stars.
0:20:01 > 0:20:05But the effects of astrology are more profound than that.
0:20:05 > 0:20:08It is precisely because people like Rudolph believed in it
0:20:08 > 0:20:12that they were prepared to pay for detailed studies of the stars.
0:20:12 > 0:20:18And these studies would prove vital when it came to developing a new vision of the cosmos.
0:20:20 > 0:20:26In Prague, there was now a powerful alignment of forces.
0:20:26 > 0:20:31The wealth and patronage of the Emperor Rudolph had brought together in one place
0:20:31 > 0:20:35star data gathered by Tycho Brahe,
0:20:35 > 0:20:40and a man with a mathematical ability to use it, Johannes Kepler,
0:20:42 > 0:20:46alongside the intellectual turmoil unleashed by the Reformation.
0:20:53 > 0:20:58All these forces coming together help explain why a new vision of the universe finally emerged here
0:20:58 > 0:21:02in Prague at the beginning of the 17th century.
0:21:04 > 0:21:10A model of the universe which placed not the Earth but the sun at the centre of everything.
0:21:14 > 0:21:16Now, this was not a new idea.
0:21:16 > 0:21:21It had been debated by Greek, Indian and Arab astronomers,
0:21:21 > 0:21:24and rediscovered by Nicholas Copernicus,
0:21:24 > 0:21:28a Polish cleric who was trying to tidy up the tangle of Greek circles.
0:21:32 > 0:21:37Copernicus is often hailed as the man who changed our vision of the universe forever.
0:21:37 > 0:21:41But his system was actually nightmarishly confusing.
0:21:41 > 0:21:45He had planets whizzing round an imaginary point somewhere near the sun.
0:21:45 > 0:21:48It was as complicated as the Greek model.
0:21:49 > 0:21:57Copernicus died before Kepler was born, and the world had not been persuaded by his arguments.
0:21:57 > 0:22:00But they had got Kepler thinking.
0:22:03 > 0:22:10Kepler was convinced that the sun, the symbol of God, produces a force which drives the planets round it.
0:22:10 > 0:22:14He was also convinced that only a sun-centred cosmos
0:22:14 > 0:22:18could possibly account for the bizarre movement of the planets.
0:22:18 > 0:22:22So, using Tycho's data, he set himself a challenge -
0:22:22 > 0:22:28explain the movement of Mars, the planet with the oddest orbit of them all.
0:22:30 > 0:22:34This is the confusion he was struggling with.
0:22:34 > 0:22:37But he thought the ancient problem with Mars could be solved.
0:22:39 > 0:22:43He believed he could explain this movement by having the Earth
0:22:43 > 0:22:47and Mars travel in circular orbits around the sun.
0:22:47 > 0:22:52Armed with Tycho's data, he set out to prove it mathematically.
0:22:52 > 0:22:55It was unbelievably tedious work.
0:22:55 > 0:22:58Hundreds and hundreds of pages of calculations,
0:22:58 > 0:23:01which took him more than five years.
0:23:01 > 0:23:05As he later wrote, "If thou, dear reader, are bored with these
0:23:05 > 0:23:11"wearisome calculations, take pity on me who did it 70 times."
0:23:18 > 0:23:24Kepler tried everything. He varied the speed of the planets,
0:23:24 > 0:23:27he shifted the positions of the orbits,
0:23:27 > 0:23:33but whatever he did he couldn't make circular orbits match Tycho's observations.
0:23:33 > 0:23:40So he did something which, for a man of his time, was daring.
0:23:40 > 0:23:46He dropped the enduring belief in divine circles, and tried other shapes,
0:23:46 > 0:23:51until finally he found one -
0:23:51 > 0:23:53an ellipse.
0:24:00 > 0:24:06At last he had created a model of the cosmos that matched the evidence.
0:24:09 > 0:24:15Kepler had demolished an edifice that had stood for more than 2,000 years,
0:24:15 > 0:24:22and replaced it with his first law of planetary motion - all planets travel in ellipses around the sun.
0:24:36 > 0:24:40You might have hoped that when Kepler published, the whole mad structure of the Greeks
0:24:40 > 0:24:43would come tumbling down. Well, it didn't.
0:24:43 > 0:24:47Many astronomers complained that he had brought physics into astronomy.
0:24:47 > 0:24:49Others simply ignored him.
0:24:49 > 0:24:53It wasn't until long after his death that his work was finally appreciated.
0:24:53 > 0:24:58As many have discovered, being right is often not enough.
0:25:01 > 0:25:07To get this new vision of the heavens noticed would require a very different set of events.
0:25:07 > 0:25:10Astronomy would have to go tabloid.
0:25:19 > 0:25:23'The story of what's out there now moves south.'
0:25:25 > 0:25:28Renaissance Italy was awash with money from trade.
0:25:29 > 0:25:35'The courts of Florence and Venice became magnets for those with talent and ambition.'
0:25:43 > 0:25:48Renaissance Italy was the perfect place for a man on the make, a man like Galileo Galilei.
0:25:48 > 0:25:51Now, he had aspirations to greatness, but at the time,
0:25:51 > 0:25:54he was a middle-aged professor of mathematics
0:25:54 > 0:25:57with three illegitimate children and few prospects.
0:25:57 > 0:26:02Yet, within a year, he would enjoy a spectacular rise,
0:26:02 > 0:26:05followed by an even more spectacular fall.
0:26:10 > 0:26:15It begins with the unexpected arrival of a stranger.
0:26:21 > 0:26:26In July 1609, word reached Galileo that a stranger had arrived in Venice,
0:26:26 > 0:26:30trying to patent a wonderful new device called the Dutch spyglass,
0:26:30 > 0:26:32which could make distant objects seem closer.
0:26:34 > 0:26:41Now, if ever there was a city where such an instrument would generate excitement, it was Venice.
0:26:45 > 0:26:51Venice is reliant on the sea, which makes it vulnerable to attack from the sea, which is why any device
0:26:51 > 0:26:56that would give you advance warning of approaching enemy ships would clearly be of enormous value.
0:27:02 > 0:27:06Galileo recognised the potential of the spyglass, but he also recognised
0:27:06 > 0:27:09that if he was going to make any money out of it,
0:27:09 > 0:27:12he was going to have to act incredibly fast.
0:27:12 > 0:27:14OK, let's go.
0:27:19 > 0:27:25Galileo had to get a fully working spyglass to the Doge of Venice before the stranger did.
0:27:27 > 0:27:32'That meant he had to design and build one from scratch.
0:27:32 > 0:27:37'Clues to how he did this come from a later shopping trip.'
0:27:37 > 0:27:41On his shopping list, which, extraordinarily enough, still exists,
0:27:41 > 0:27:45he had written, "Chickpeas and slippers for my son."
0:27:45 > 0:27:51But he's also written down, "Glass, artillery balls and an organ pipe,"
0:27:51 > 0:27:55and this is what you need if you are going to build a Dutch spyglass,
0:27:55 > 0:27:59a device later renamed the telescope.
0:28:03 > 0:28:07The best place to buy glass was the island of Murano, just across the lagoon.
0:28:10 > 0:28:16'Here, a group of craftsmen had a skill so precious, they were barred from leaving Venice.'
0:28:21 > 0:28:26That skill was the ability to make glass of crystal-like purity.
0:28:31 > 0:28:32Perfect!
0:28:32 > 0:28:33Wonderful!
0:28:36 > 0:28:38Whoo!
0:28:38 > 0:28:42We have a new glass-blowing master!
0:28:42 > 0:28:44That was fun, thank you.
0:28:50 > 0:28:52He smashes it up!
0:28:55 > 0:28:58The glass was known as Cristallo.
0:28:58 > 0:29:03It was bought by the aristocrats of Europe to adorn their tables.
0:29:03 > 0:29:08It was the first really clear, colourless glass ever produced,
0:29:08 > 0:29:16and it was probably this glass that allowed Galileo to build a telescope of stunning optical quality.
0:29:20 > 0:29:24400 years ago, glassmakers started with a bottle,
0:29:24 > 0:29:27and then opened it up into a sheet.
0:29:29 > 0:29:33'The first stage to making a telescope lens.'
0:29:36 > 0:29:40I've got glass from Murano, and I've got an artillery ball.
0:29:40 > 0:29:45And I'm off to meet a lens grinder who apparently can use this to turn this into a telescope lens.
0:29:47 > 0:29:50- Buongiorno.- Ah, buongiorno, Michael.
0:29:50 > 0:29:53- Hello. Have that one.- Ah, va bene!
0:29:54 > 0:30:00'In the autumn of 1609, Galileo himself began to grind and polish lenses.'
0:30:02 > 0:30:05- HE SPEAKS ITALIAN - Ah, OK.
0:30:07 > 0:30:12'By trying out different lenses, made with different sized artillery balls, he was able
0:30:12 > 0:30:16'to produce magnifications of six and then 20 times.'
0:30:20 > 0:30:26It might seem surprising that a mathematician like Galileo would want to get his hands dirty in
0:30:26 > 0:30:31this way. But it's part of the important emerging trend in the 16th and 17th century.
0:30:31 > 0:30:34People were no longer satisfied just to intellectualise,
0:30:34 > 0:30:38they were making instruments and they were testing them out.
0:30:43 > 0:30:51The fact that Galileo, a professor of mathematics, was grinding his own lenses, is of real significance.
0:30:51 > 0:30:56This joining of the skills of scholars and craftsmen
0:30:56 > 0:30:59was key to the emerging power of European science.
0:31:07 > 0:31:11Galileo now took his new lenses, and through a process of trial and error,
0:31:11 > 0:31:15worked out what the ideal distance was between them
0:31:15 > 0:31:20to get maximum magnification along with maximum sharpness.
0:31:20 > 0:31:25He then packaged them together into a new spyglass.
0:31:25 > 0:31:29Now, what was truly impressive is that it had only been a few weeks
0:31:29 > 0:31:34since he'd first heard of the Dutch spyglass, and yet he produced something which was far superior.
0:31:34 > 0:31:38He now got together some influential Venetians, took them up the tower,
0:31:38 > 0:31:41and pointed his new spyglass out at sea.
0:31:55 > 0:31:58Its value was not lost on the Venetians.
0:31:58 > 0:32:03You could now see ships two hours sooner than with the naked eye.
0:32:06 > 0:32:10Galileo's climb to fame and fortune had begun.
0:32:12 > 0:32:17'And then, fatefully, he lifted his telescope to the heavens.'
0:32:28 > 0:32:33His telescope now uncovered dramatic new evidence about the cosmos.
0:32:35 > 0:32:40'Evidence that would bring the idea of a sun-centred universe to the fore.
0:32:44 > 0:32:49'I'm going to see the night skies as he would have done 400 years ago.'
0:32:55 > 0:32:58Francesco, it has to be. Who else in the middle of the night?
0:32:58 > 0:33:00- Hello, Michael.- Michael Mosley.
0:33:00 > 0:33:05I have my Galileo telescope, which magnifies about sixfold.
0:33:05 > 0:33:07I'm guessing yours does a bit more.
0:33:07 > 0:33:09This one does 20, 20 times.
0:33:09 > 0:33:14- So this is optically identical, pretty much, to what Galileo had to deal with.- That's right. Yeah.
0:33:14 > 0:33:18Because the lenses have been analysed and studied and
0:33:18 > 0:33:23reproduced with the same properties as the ones that Galileo used.
0:33:23 > 0:33:27- Can I have a look?- Yes. - I haven't really properly looked through something like this before.
0:33:27 > 0:33:31Shall I start with that one there? Right.
0:33:31 > 0:33:33Ah! Gorgeous!
0:33:35 > 0:33:41This is what Galileo's lenses were able to show of the surface of the moon.
0:33:44 > 0:33:47Night after night, he observed its phases.
0:33:53 > 0:33:57His drawings are not just detailed, they are beautiful.
0:33:59 > 0:34:05For me, it's basically, there's a lot of shimmer going on and it sort of pops in and out of focus.
0:34:05 > 0:34:11I'm absolutely amazed that Galileo could draw the images at that level of accuracy.
0:34:11 > 0:34:13I mean, really phenomenal.
0:34:16 > 0:34:19This was how Galileo saw Jupiter.
0:34:21 > 0:34:27No-one had seen these bright objects either side of it before.
0:34:27 > 0:34:29They are moons, circling the planet.
0:34:31 > 0:34:35And if there are moons circling a planet which is not the Earth...
0:34:38 > 0:34:44did that perhaps suggest that the Earth was not really the centre of everything?
0:34:46 > 0:34:51I must admit, having seen this, I have enormous, enormous respect for Galileo now.
0:34:51 > 0:34:56I always saw him as a bit of a chancer, to be honest, but having seen what he did with a machine
0:34:56 > 0:34:59with these limitations, it makes you think, wow!
0:35:01 > 0:35:07He now took full advantage of another Renaissance invention, the printing press.
0:35:10 > 0:35:14He put his findings together into this book, The Starry Messenger.
0:35:14 > 0:35:19Unusually for an astronomical book of its time, it is well written,
0:35:19 > 0:35:22it has lovely pictures and very little maths.
0:35:22 > 0:35:26In fact, it soon became a 17th century bestseller.
0:35:31 > 0:35:34'The book made him famous, and that encouraged him
0:35:34 > 0:35:38'to do what he loved best, courting controversy and attention.
0:35:40 > 0:35:45'Galileo had become convinced that the sun was at the centre of the cosmos.
0:35:45 > 0:35:51'Now he began to promote that idea amongst influential people.'
0:35:58 > 0:36:01His timing was terrible.
0:36:01 > 0:36:06The Reformation had challenged the power of the Catholic Church.
0:36:08 > 0:36:14Many within the Church now wanted to re-assert control.
0:36:14 > 0:36:18A fight with Galileo suited them.
0:36:22 > 0:36:26And then, in 1632, it all went terribly wrong for Galileo.
0:36:26 > 0:36:29He published a book that destroyed his life.
0:36:29 > 0:36:35The book enraged the Pope, and remained on the index of prohibited books for more than 200 years.
0:36:35 > 0:36:39It's called The Dialogue.
0:36:43 > 0:36:47He had been given permission to write this book, on condition it was balanced.
0:36:50 > 0:36:54The book is presented as a series of discussions about the cosmos.
0:36:56 > 0:37:01One side arguing for a stationary Earth at the centre,
0:37:01 > 0:37:03the other favouring the sun.
0:37:05 > 0:37:13But despite what he'd promised, Galileo clearly came down on the side of the sun at the centre.
0:37:17 > 0:37:24But worst of all, what he was really saying is there are truths which go beyond the realms of religion,
0:37:24 > 0:37:30or, as he once put it, "The Bible teaches us how to go to heaven, not how the heavens go."
0:37:32 > 0:37:37Make no mistake, this was a huge challenge to the Church.
0:37:37 > 0:37:43Galileo was saying that science can discover truths about nature
0:37:43 > 0:37:46using its own methods of investigation.
0:37:46 > 0:37:52And so, in 1633, he was brought to Rome to stand trial before the Inquisition.
0:37:55 > 0:37:58The story of Galileo is often told as scientific hero
0:37:58 > 0:38:03takes on reactionary Church over the question of a sun-centred universe.
0:38:03 > 0:38:05But it wasn't really like that.
0:38:05 > 0:38:12The trial of Galileo was actually about authority, who owns the truth about the heavens.
0:38:15 > 0:38:18He was tried and found guilty.
0:38:27 > 0:38:33The sentence broke him. Old, ill, in pain, he was condemned to life imprisonment,
0:38:33 > 0:38:38and he spent much of it here at his villa in Arcetri, in the foothills above Florence.
0:38:38 > 0:38:44Ironically, the banning of The Dialogue ensured that the book was widely read
0:38:44 > 0:38:47in other countries, as people scrambled to get hold of a copy
0:38:47 > 0:38:50and discover what all the fuss was about.
0:38:59 > 0:39:03It was a moment of human reckoning.
0:39:03 > 0:39:07We no longer sat at the centre of the universe,
0:39:07 > 0:39:11just on another planet circling the sun.
0:39:17 > 0:39:20The attempts to gag Galileo were utterly futile.
0:39:20 > 0:39:25Within a generation, the educated classes throughout Europe had accepted that the sun and not
0:39:25 > 0:39:29the Earth is at the centre of the solar system.
0:39:34 > 0:39:40It happened, not in a single moment of genius, but as a result of a series of connections.
0:39:40 > 0:39:44The patronage of the princely courts of the Renaissance.
0:39:44 > 0:39:48A combination of different talents -
0:39:48 > 0:39:53Tycho Brahe, Johannes Kepler, and Galileo Galilei.
0:39:55 > 0:39:58Technological innovation,
0:39:58 > 0:40:00raw data from telescopes,
0:40:00 > 0:40:05and the power of the printing press to spread the new knowledge.
0:40:10 > 0:40:14When you think about it, it is astonishing that nearly a century
0:40:14 > 0:40:19separates Copernicus first publishing his book claiming that the Earth goes round the sun,
0:40:19 > 0:40:24and Galileo's trial, after which, the idea finally gets widespread acceptance.
0:40:24 > 0:40:29And when you look at it in that light, you realise that this claim, you get these violent
0:40:29 > 0:40:35upheavals in intellectual thought which change everything overnight, well, that claim is clearly myth.
0:40:35 > 0:40:40It is largely created by the comfort and distance of hindsight.
0:40:41 > 0:40:44So, no sudden revolution, then.
0:40:46 > 0:40:53As so often in science, what happened is that people who hold the old views slowly die off,
0:40:53 > 0:40:57and a new generation comes in that sees things differently.
0:41:07 > 0:41:14There was now a new force driving interest in the heavens - global trade.
0:41:19 > 0:41:24Economic power in Europe was shifting away from the Mediterranean countries,
0:41:24 > 0:41:29towards the Atlantic nations, like Spain, Portugal and England.
0:41:32 > 0:41:38As new trade routes opened up, ships' captains needed better star maps to steer by.
0:41:40 > 0:41:44Governments funded newer and better telescopes.
0:41:46 > 0:41:48Astronomical evidence poured in.
0:41:48 > 0:41:52New questions were being asked.
0:41:52 > 0:41:56Why did the Earth and the planets move in giant ellipses?
0:41:59 > 0:42:02And what was it that held the cosmos together?
0:42:10 > 0:42:14One of the cargoes those ships brought to Europe was coffee.
0:42:18 > 0:42:25'Coffee led to coffee shops, places where traders, ships' captains and assorted thinkers met,
0:42:25 > 0:42:27'and fuelled up on caffeine.
0:42:29 > 0:42:31'They became known as penny universities.'
0:42:33 > 0:42:34Thank you very much.
0:42:38 > 0:42:44Learned gentlemen would come to coffee shops to debate the central burning questions of the day.
0:42:44 > 0:42:49And one of the key questions was, what is it that keeps the planets in their place?
0:42:49 > 0:42:53Well, in 1684, this led to a bet.
0:42:53 > 0:42:58At stake was two pounds, about a week's salary, but this would turn out
0:42:58 > 0:43:02to be one of the most significant wagers ever made.
0:43:08 > 0:43:13To win the bet, what they had to do was to prove that the elliptical path that planets take around
0:43:13 > 0:43:19the sun, which Kepler described, obey a simple mathematical rule.
0:43:19 > 0:43:24Now, smart though they were, they soon realised they were going to need help.
0:43:28 > 0:43:33'One of the men who'd taken the bet, the astronomer Edmund Halley, set off in search of help,
0:43:33 > 0:43:40'to Cambridge, to find the Lucasian professor of mathematics, a certain Isaac Newton.'
0:43:43 > 0:43:48Halley manages to track Newton down, and he tells him about the bet.
0:43:48 > 0:43:51Then Newton, to Halley's complete amazement, says,
0:43:51 > 0:43:56"Actually, I've solved that problem, I've done the calculations, and they're here somewhere."
0:43:56 > 0:43:59And he sort of rummages around amongst these papers.
0:43:59 > 0:44:03But he can't find them. So he says to Halley, "I'll send them on to you."
0:44:03 > 0:44:08The important thing about this visit is it seems to have triggered something in Newton's brain.
0:44:10 > 0:44:13The memory of a time 20 years earlier.
0:44:17 > 0:44:22A time when Newton returned to his family farm to escape an outbreak of the plague.
0:44:24 > 0:44:28It was certainly safer, but I'm not sure how pleased he was to be back.
0:44:28 > 0:44:32As a young man, he'd threatened to burn the house down with his mother and stepfather in it.
0:44:32 > 0:44:37Described as artificial, unkind, arrogant, he was also
0:44:37 > 0:44:41one of the most brilliant minds of his or any other generation.
0:44:41 > 0:44:47'There are few more famous legends in the whole history of science
0:44:47 > 0:44:49'than that of Newton in the orchard.
0:44:51 > 0:44:58'That moment of genius when the young Isaac Newton first worked out a comprehensive theory of gravity.'
0:45:00 > 0:45:03It's one of the great eureka moment stories.
0:45:03 > 0:45:06Newton's in the orchard when he sees the apple fall.
0:45:06 > 0:45:11The falling apple is said to have triggered a cascade of thoughts in Newton's mind.
0:45:11 > 0:45:14Why is it apples always fall down?
0:45:14 > 0:45:18Why doesn't it sometimes go sideways, or even upwards?
0:45:18 > 0:45:22And if there is a force that is pulling it down, could it be that
0:45:22 > 0:45:27same force is holding the moon in its rotation around the Earth?
0:45:27 > 0:45:31And in that moment, the theory of gravitation is born.
0:45:36 > 0:45:39Except the story's almost certainly made up.
0:45:39 > 0:45:45Newton only started telling that story when he was an old man, and he possibly did it
0:45:45 > 0:45:50because he wanted to ensure that he and he alone got full credit for coming up with a theory of gravity.
0:45:50 > 0:45:55What is certain is that if he had a moment of divine inspiration
0:45:55 > 0:45:59in this orchard, he did nothing with it for nearly 20 years.
0:46:01 > 0:46:08It seems it was Halley's visit that prompted Newton to really develop his ideas.
0:46:08 > 0:46:12He would express his thinking about gravity in a famous thought experiment.
0:46:14 > 0:46:19He imagined a cannon on top of a high mountain.
0:46:19 > 0:46:26He thought, if the ball leaves a cannon slowly, gravity would pull it to Earth.
0:46:26 > 0:46:29If the ball is fired too quickly,
0:46:29 > 0:46:31it would disappear into space.
0:46:31 > 0:46:35But if the speed is just right,
0:46:35 > 0:46:41then the force of gravity would hold the ball in orbit round the Earth, just like the moon.
0:46:41 > 0:46:45An orbit that follows a simple mathematical law.
0:46:49 > 0:46:57His monumental work, explaining that gravity held the universe together, was published in 1687.
0:46:57 > 0:47:03This is Principia by Newton, and it is beautiful.
0:47:03 > 0:47:07I have never held this book before, and I can feel
0:47:07 > 0:47:12a little shiver going up my spine, because this is the book
0:47:12 > 0:47:19which really did transform the world and in fact would go on to dominate science for the next 200 years.
0:47:28 > 0:47:31This was when the new vision of the universe truly came together,
0:47:31 > 0:47:36built on Tycho's observations,
0:47:38 > 0:47:40Kepler's elliptical orbits,
0:47:42 > 0:47:45and Galileo's discoveries.
0:47:49 > 0:47:55Now Newton outlined universal laws of motion that explained how the planets moved.
0:48:02 > 0:48:07Newton was clearly a scientific giant, but he was also much more than that.
0:48:07 > 0:48:13The way that he had shown that a few universal laws could explain so much of the physical world inspired other
0:48:13 > 0:48:19intellectuals to look for universal laws that could explain human behaviour, politics, even history.
0:48:22 > 0:48:28Newton became a hero to revolutionaries who dreamt of utopian societies founded on reason.
0:48:32 > 0:48:37In America, politicians were inspired by Newton's laws of action and reaction
0:48:37 > 0:48:41when they created their famous political system of checks and balances.
0:48:44 > 0:48:49And in religion, an ordered universe was taken to demonstrate
0:48:49 > 0:48:52the existence of a God of infinite power.
0:49:00 > 0:49:02And astronomy?
0:49:05 > 0:49:11There was now a new stable model of the universe, a clockwork universe,
0:49:11 > 0:49:14governed by a few simple laws.
0:49:19 > 0:49:23And that's how things stayed for the next 200 years.
0:49:30 > 0:49:36The question of what is out there has always followed the money.
0:49:36 > 0:49:40And in the early 20th century, it headed across the Atlantic
0:49:40 > 0:49:44to California, where they were enjoying an oil rush.
0:49:46 > 0:49:51Oil and railway barons, like Renaissance princes before them,
0:49:51 > 0:49:54craved the sort of fame that astronomy could bring.
0:49:59 > 0:50:01One philanthropist, who had made his money building
0:50:01 > 0:50:08pipelines and selling hardware, helped finance the next radical shift in our view of the cosmos.
0:50:10 > 0:50:15John D Hooker was persuaded to donate 45,000 towards building
0:50:15 > 0:50:18the largest telescope the world had ever seen.
0:50:18 > 0:50:23And they dragged it up Mount Wilson, this mountain, which is just outside Los Angeles.
0:50:30 > 0:50:33It is a fantastic structure.
0:50:33 > 0:50:40'A hundred tons of pipework, hardware and glass floats on a bed of mercury,
0:50:40 > 0:50:43'allowing it to compensate for the Earth's rotation.'
0:50:53 > 0:50:55Isn't that magnificent?
0:50:55 > 0:50:58Over 90 years old and still fully operational.
0:51:01 > 0:51:05But for this gargantuan telescope to fulfil its true potential,
0:51:05 > 0:51:09it would need a character who was also larger than life.
0:51:13 > 0:51:17Edwin Hubble was an exceptionally colourful scientist.
0:51:23 > 0:51:25After a spell at Oxford University,
0:51:25 > 0:51:28he came home with a faux upper-class accent,
0:51:28 > 0:51:32and worked in jodhpurs and high-topped riding boots.
0:51:34 > 0:51:39He was also exceptionally fortunate to be hired to work with the new Hooker telescope.
0:51:43 > 0:51:48Now, Hubble was a brilliant astronomer, and he had the world's largest telescope.
0:51:48 > 0:51:52Now the thing is, even with a telescope this big, the human eye is just not good enough
0:51:52 > 0:51:55to pick out the detail that was needed.
0:51:58 > 0:52:01So there was a camera attached to the telescope.
0:52:03 > 0:52:09And with it, Hubble photographed stars at the far reaches of the Milky Way,
0:52:09 > 0:52:13at that time, the only known galaxy in the universe.
0:52:16 > 0:52:20On the 6th October 1923, Hubble took a photograph
0:52:20 > 0:52:23that must rank as one of the most significant photographs ever taken.
0:52:26 > 0:52:32This photograph demonstrated for the first time just how vast the universe truly is.
0:52:43 > 0:52:48Now, what you can see here is a black, swirly area, which is actually the Andromeda nebula.
0:52:48 > 0:52:52But what got Hubble excited was a little black speck here,
0:52:52 > 0:52:55which he's labelled as VAR, or variable star.
0:52:59 > 0:53:02This was a huge discovery.
0:53:05 > 0:53:11The pulsing of a variable star could be used to calculate its distance from Earth.
0:53:11 > 0:53:15Hubble came to a startling conclusion.
0:53:15 > 0:53:21His star, and the nebula in which it sat, were almost a million light years away,
0:53:21 > 0:53:24far further than had been thought possible.
0:53:26 > 0:53:32Now, Hubble realised that he could prove for the first time that the nebula was actually a galaxy,
0:53:32 > 0:53:36and it sat way outside our own galaxy.
0:53:38 > 0:53:46Suddenly, the human race, our world, our concerns, became cosmically insignificant.
0:53:49 > 0:53:56We are just one small planet in a vast galaxy, that sits amongst billions of other galaxies.
0:54:01 > 0:54:04The implications of what they had found were disturbing.
0:54:04 > 0:54:08The universe was vast, possibly limitless.
0:54:08 > 0:54:12But what they did next was even more shocking.
0:54:12 > 0:54:17They linked this giant telescope up with a device called a spectrograph,
0:54:17 > 0:54:21and they pointed it once more at the skies.
0:54:21 > 0:54:26They were hunting for objects which they now believed to be galaxies, and using the spectrograph,
0:54:26 > 0:54:31they measured the speed at which those galaxies were either coming towards or away from us.
0:54:37 > 0:54:40What they found was the vast majority of these galaxies
0:54:40 > 0:54:47were actually receding, and some at quite astonishing speeds of well over a million miles an hour.
0:54:50 > 0:54:56Now, the implication of this was obvious, the universe is expanding.
0:54:56 > 0:55:00Now, this really blew out of the water the old way of thinking.
0:55:00 > 0:55:05Gone forever was the old static, stable, Newtonian clockwork model.
0:55:05 > 0:55:12It seems, now, we are actually living through a giant cosmic explosion.
0:55:12 > 0:55:16It seems our universe had a beginning.
0:55:21 > 0:55:2313 billion years ago.
0:55:25 > 0:55:28This became known as the Big Bang.
0:55:30 > 0:55:34Edwin Hubble never felt he achieved the recognition he craved
0:55:34 > 0:55:39for his discovery of the vastness of the cosmos.
0:55:39 > 0:55:45But floating high above the Earth is the ultimate tribute to this eccentric astronomer.
0:55:47 > 0:55:49The Hubble space telescope.
0:55:51 > 0:55:54400 years since Galileo ground his first lenses,
0:55:54 > 0:55:58this is what we use to look at what's out there.
0:56:01 > 0:56:09It can peer billions of light years across the universe, back in time towards the birth of everything.
0:56:16 > 0:56:22Our journey to find out what's out there has been shaped by powerful forces and beliefs.
0:56:22 > 0:56:26The Greek obsession with divine circles.
0:56:26 > 0:56:29The courts of the Renaissance.
0:56:29 > 0:56:31By religious upheaval.
0:56:33 > 0:56:37Above all, by the marriage of two skills -
0:56:37 > 0:56:40the making of instruments and the generating of ideas.
0:56:40 > 0:56:44And it's still going on,
0:56:44 > 0:56:50as we find new ways of looking ever deeper into our universe.
0:56:54 > 0:56:56So, what is out there?
0:56:56 > 0:56:59Well, rather a lot.
0:57:02 > 0:57:06We've seen the birth of stars, in nurseries of gas and dust.
0:57:09 > 0:57:13Evidence of super massive black holes.
0:57:13 > 0:57:19Clues to dark energy that may make up most of our universe.
0:57:29 > 0:57:34Some of these ideas are as strange and unsettling to us
0:57:34 > 0:57:39as the Earth going round the sun was to contemporaries of Galileo.
0:57:40 > 0:57:47But I think what this journey really boils down to is trust in evidence.
0:57:48 > 0:57:52'Because no matter how strange the conclusions may seem,
0:57:52 > 0:57:56'it's only by accepting evidence that we have come to understand
0:57:56 > 0:58:01'not just the universe, but also our place here within it.'
0:58:06 > 0:58:09Isaac Newton, in a moment of uncharacteristic modesty,
0:58:09 > 0:58:15once said that he was just a child playing on the shores of a vast ocean of undiscovered truths.
0:58:15 > 0:58:19But I think the contribution he and his fellow stargazers really made
0:58:19 > 0:58:25was to open up our minds to what is going on, not just up in the heavens, but down here on Earth.
0:58:34 > 0:58:39'Next time - delving deep to find beauty and order.
0:58:39 > 0:58:43'What is the world made of?'
0:59:00 > 0:59:03Subtitles by Red Bee Media Ltd
0:59:03 > 0:59:06E-mail - subtitling@bbc.co.uk