The BEST Episodes of Horizon

Every episode ever - ranked by fan votes!

Last Updated: Oct 24, 2019

Network: BBC Two

Horizon is BBC Two's flagship 50-minute science documentary series. In September 2014 it celebrated its 50th anniversary and it continues to enjoy outstanding critical acclaim. Recognised as the world leader in its field, it regularly wins a sweep of international science, medical and environmental film accolades, and has recently won the Royal Television Society Award and the Prix Italia. In 2002, the British Academy of Film & Television Arts presented Horizon with the BAFTA Television Award for Best Factual Series or Strand. In 2003 it won the prestigious Images et Science award for best medical documentary and the Carl von Linne Award at the Living Europe film festival in Sweden. That year, a Horizon co-production with WGBH Boston won the Emmy for best documentary.

Prof. Regan's Supermarket Secrets

#1 - Prof. Regan's Supermarket Secrets

Season 2008 - Episode 7

Friendly bacteria, superfoods, cholesterol busting spreads, 99% germ free, whiter than's almost impossible to find a product in the supermarket today that doesn't come with impressive claims...a scientific claims, but do they actually do what they say? Are they worth the price? Are they worth a place in Prof. Regan's shopping trolly?

star 10.00
1 votes
Inside Chernobyl's Sarcophagus (Update)

#2 - Inside Chernobyl's Sarcophagus (Update)

Season 1996 - Episode 10

In this episode of Horizon, which is a follow-up to the 1991 documentary, we follow a group of soviet scientists on a suicide mission as they search for the missing nuclear fuel inside the remains of the nuclear reactor 4.

star 10.00
1 votes
The Secret You

#3 - The Secret You

Season 2009 - Episode 13

With the help of a hammer-wielding scientist, Jennifer Aniston and a general anaesthetic, Professor Marcus du Sautoy goes in search of answers to one of science's greatest mysteries: how do we know who we are? While the thoughts that make us feel as though we know ourselves are easy to experience, they are notoriously difficult to explain. So, in order to find out where they come from, Marcus subjects himself to a series of probing experiments. He learns at what age our self-awareness emerges and whether other species share this trait. Next, he has his mind scrambled by a cutting-edge experiment in anaesthesia. Having survived that ordeal, Marcus is given an out-of-body experience in a bid to locate his true self. And in Hollywood, he learns how celebrities are helping scientists understand the microscopic activities of our brain. Finally, he takes part in a mind-reading experiment that both helps explain and radically alters his understanding of who he is.

star 10.00
1 votes
Molecules With Sunglasses

#4 - Molecules With Sunglasses

Season 1992 - Episode 3

About the original discovery in 1985 of a third form of solid carbon, named Buckminsterfullerene after the architect who invented geodesic domes. The two scientists who discovered the material glimpsed it for brief seconds only in their lasers but neither they nor other scientists subsequently could make the substance last long enough in the laser to prove their theory. Then in 1990, a couple of physicists with an arc-welder in a bell-jar found they could make as much Buckminsterfullerene as they liked, and industrial applications opened up, with talk of new polymers, molecular ball-bearings, lubricants and super- conductors. Meanwhile, the original discoverers were turning back to the fundamental questions surrounding the discovery, such as how and why does it form; does it exist in space or is it the solution to one of the great mysteries of the universe.

star 10.00
1 votes
Malaria: Battle of the Merozoites

#5 - Malaria: Battle of the Merozoites

Season 1992 - Episode 5

In this episode, Horizon look at attempts to persuade major respected organizations to do controlled trials on a synthetic malaria vaccine.

star 10.00
1 votes
Cannabis: Miracle Medicine or Dangerous Drug?

#6 - Cannabis: Miracle Medicine or Dangerous Drug?

Season 2019 - Episode 6

At a pivotal moment in the history of one of the world’s oldest drugs, Dr Javid Abdelmoneim investigates the latest medical and scientific research into the effects of cannabis on the brain and body.

star 9.50
2 votes
Do You Know What Time It Is?

#7 - Do You Know What Time It Is?

Season 2008 - Episode 15

Particle physicist Professor Brian Cox asks, 'What time is it?' It's a simple question and it sounds like it has a simple answer. But do we really know what it is that we're asking? Brian visits the ancient Mayan pyramids in Mexico where the Maya built temples to time. He finds out that a day is never 24 hours and meets Earth's very own Director of Time. He journeys to the beginning of time, and goes beyond within the realms of string theory, and explores the very limit of time. He discovers that we not only travel through time at the speed of light, but the experience we feel as the passing of time could be an illusion.

star 9.33
9 votes
Einstein's Unfinished Symphony

#8 - Einstein's Unfinished Symphony

Season 2005 - Episode 2

The unpredictable results of the Theory of Relativity. Horizon brings you the second part of a two-part series on Albert Einsten. In the summer of 1939 Albert Einstein was on holiday in a small resort town on the tip of Long Island. His peaceful summer, however, was about to be shattered by a visit from an old friend and colleague from his years in Berlin. The visitor was the physicist Leo Szilard. He had come to tell Einstein that he feared the Nazis could soon be in possession of a terrible new weapon and that something had to be done.

star 9.00
5 votes
Now the Chips Are Down

#9 - Now the Chips Are Down

Season 1978 - Episode 9

About the applications and implications for the future, particularly the effects on the labour market, of microprocessors.

star 9.00
4 votes
Einstein's Equation of Life and Death

#10 - Einstein's Equation of Life and Death

Season 2005 - Episode 3

The story of Einstein's most famous equation E=mc² – its role in the creation of the atom bomb and our understanding of the beginnings of the Universe. Horizon brings you the second part of a two-part series on Albert Einsten. In the summer of 1939 Albert Einstein was on holiday in a small resort town on the tip of Long Island. His peaceful summer, however, was about to be shattered by a visit from an old friend and colleague from his years in Berlin. The visitor was the physicist Leo Szilard. He had come to tell Einstein that he feared the Nazis could soon be in possession of a terrible new weapon and that something had to be done.

star 9.00
1 votes
Malaria: Defeating the Curse

#11 - Malaria: Defeating the Curse

Season 2005 - Episode 11

This is the story by Horizon of an epic battle between science and nature. It's a battle to destroy a disease that is one of the biggest killers on the planet: malaria.

star 9.00
1 votes
How Violent Are You?

#12 - How Violent Are You?

Season 2009 - Episode 11

What makes ordinary people commit extreme acts of violence? Michael Portillo investigates the dark side of human nature, and discovers what it is like to inflict pain.

star 9.00
1 votes
Dr Money and the Boy with No Penis

#13 - Dr Money and the Boy with No Penis

Season 2004 - Episode 18

On 22 August 1965 Janet Reimer was granted her dearest wish: she gave birth to twins. The two boys, Brian and Bruce, were healthy babies, but they would lead tragic lives, blighted by one scientist's radical theory. When they were seven months old, the boys, who lived in Winnipeg, Canada, were sent to the local hospital for a routine circumcision. Unfortunately the doctor in charge of the procedure was using electrical equipment, which malfunctioned several times. On the last trial, Bruce's entire penis was burnt off. Brian was not operated on. The family were distraught. In the Sixties plastic surgery was not an option: even today it is not recommended that new-borns undergo penis reconstruction operations. It wasn't until several months later that Janet and her husband, Ron, saw a television programme that gave them some hope. Dr John Money, a highly renowned sexologist, featured in a debate about sex change operations on transsexuals. He had brought a transsexual with him who was convincingly feminine looking. Perhaps, thought Janet Reimer, this was the solution - they could turn their baby son into a daughter. She wrote to Dr Money immediately. He responded swiftly and invited them to come and visit him in Baltimore, Maryland. Dr Money is a highly intelligent, well respected, charismatic individual. He suggested to the Reimers that they bring their son up as a girl. Thus, when Bruce was 18 months old, he was castrated and a rudimentary vulva was created for him. The family now called him Brenda and tried to treat him like a little girl. Dr Money was the answer to the Reimers' prayers, but they were the answer to his too. He had studied people known then as hermaphrodites, now referred to as intersex, who are physically both male and female. As it was surgically easier to turn these people into females, this was standard practice. Dr Money had used case studies of hermaphrodites to show that there was a window of opportunity for surgery - a 'gender gate' - which lasted up to the age of two. During that period, he argued, if the parents chose the sex of the child, the way they brought it up would determine the child's gender, not its physical characteristics. But until this point, Dr Money had never put his controversial theory into practice with a non-intersex child. Now he had the perfect and unplanned opportunity to do so: a set of identical twins, two biological boys, one of whom could be raised a girl. Janet Reimer wrote to Dr Money of Brenda's progress and once a year the whole family visited him in Baltimore. When Brenda was five Dr Money started to publish her case - disguising her by referring to her as Joan/John - in his books. The case became a sensation. It was the proof that feminists in particular were looking for. It was proof, they argued, that there was no biological reason that boys are better at maths and that men should earn more than women. Nurture not nature determines whether we feel feminine or masculine. Widely cited in many text books, the case was a landmark study - hailed as proof of the overwhelming force of nurture - in spite of increasing evidence that hormones both in the womb and throughout a child's life, play a huge part in an individual's perception of themselves as masculine or feminine. Meanwhile, back in Canada, things were not so good for the Reimer family. Brenda behaved in a distinctly masculine fashion. She liked running and fighting and climbing and loathed playing with dolls. She had no friends and was increasingly lonely as her twin Brian was embarrassed to play with her in front of his other friends. She hated going to visit Dr Money. He insisted that to fully understand that she was a girl, she needed to grasp the difference between men and women, and frequently spoke to her about her genitalia. He took photographs of her and her brother naked. He tried to persuade her to have a vagina constructed, which, at the time, would have been made out of section of her bowel or else from the skin of her thigh, which would then be inserted into the pelvic region. He showed her graphic photographs of a woman giving birth when she was seven years old in an attempt to get her to agree to having a 'baby-hole' made. He also suggested strongly that she take hormone tablets in order to make her grow breasts when she was 12. Other scientists, including Dr Money's ex-students, argue that he did these things in the best possible interests for his patient - to make her believe that she was indeed a girl. Brenda however felt traumatised and became suicidal. Finally when she was 13, the family told her and Brian the truth. Brenda was intensely relieved as she had felt she was going insane. Almost immediately she turned herself back into a boy and called herself David. David received compensation money for the circumcision and used this to pay for surgery to have a new penis constructed. In his early twenties he met Jane Fontane, who had three children of her own, and they married. Unfortunately, his relationship with his brother worsened. Brian had felt that David, as Brenda, had received all the attention when they were growing up; once he discovered that he was no longer the only boy in the family, he became extremely angry. It was the start of mental disturbance that would develop into schizophrenia. After two failed marriages, he died, possibly of a drug overdose, which may have been a suicide attempt. David had never managed to complete his education and had to take semi-skilled work. He was made redundant and was unemployed for a year. He sold the movie rights to his story, but lost the money when a business man absconded with his investment. Stricken with grief for his brother, his marriage started to fail. Jane asked him for a short separation period, but David took this very badly. He returned to his parents' house for a few days, before driving to a supermarket car park on 4 May 2004 and shooting himself in the head. He was 38 years old. Dr Money argues that he cannot be held to blame because David did not accept a female gender identity. He says that the family delayed making a decision until their son was almost two, just before the gender gate was about to shut. Others, however, argue that he could have admitted he made a mistake when the case clearly was not working, for he continued to let people believe that it had been successful long after he had stopped seeing Brenda and she had become David. It is, perhaps above all, a cautionary tale of what may happen when a scientist falls in love with a beautiful theory and ignores the ugly facts.

star 9.00
1 votes
Crater of Death

#14 - Crater of Death

Season 1997 - Episode 10

Horizon investigates the theory that a comet impact in the Gulf of Mexico was responsible for the mass extinction of the dinosaurs.

star 9.00
3 votes
Noah's Flood

#15 - Noah's Flood

Season 1996 - Episode 16

Follows the work of geologists Bill Ryan and Walter Pitman, who for twenty five years have been investigating evidence for the location of the biblical flood and Noah's Ark.

star 9.00
1 votes
The Runaway Mountain

#16 - The Runaway Mountain

Season 1995 - Episode 20

Horizon presents the story of the search for an explanation of how rock can flow like water.

star 9.00
1 votes
The Pleasure Of Finding Things Out

#17 - The Pleasure Of Finding Things Out

Season 1981 - Episode 24

Richard Feymann was one of the most brilliant theoretical physicists and original thinkers or the 20th century. He rebuilt the theory of quantum electrodynamics, and it was for this work that he won the Nobel Prize in 1965. In this documentary he talks about his motivations to be a scientist and a teacher of science.

star 9.00
5 votes
Before Babel

#18 - Before Babel

Season 1992 - Episode 12

Horizon explores the development of languages all over the world and attempts to reconstruct the first spoken words.

star 9.00
1 votes
No Ordinary Genius (1)

#19 - No Ordinary Genius (1)

Season 1993 - Episode 4

This is the first part of a two-part Horizon series presenting a portrait of Richard Feynman, the American Nobel Prize winning physicist.

star 9.00
3 votes
The 250 Million Pound Cancer Cure

#20 - The 250 Million Pound Cancer Cure

Season 2019 - Episode 5

Proton beam therapy is the one of the most technologically advanced though expensive cancer treatments in the world - but it has the potential to save the lives of children with otherwise incurable cancers. Over two years, Horizon follows the engineers, scientists and medics as they race to build two new centres, one at the Christie Hospital in Manchester and one at University College Hospital in London, as well as following as the first children awaiting the lifesaving treatment. This is one of the most complex challenges the NHS has ever attempted. At the cutting edge of particle physics, proton beam therapy involves splitting hydrogen atoms to create a beam of protons travelling at two-thirds the speed of light, which target tumours with millimetre precision. But doing this in the heart of two of our biggest cities is no easy feat. The process generates so much radiation it needs to be housed in a maze-like nuclear bunker, with walls four metres thick. 2,000 tonnes of precision instruments are installed - more than four jumbo jets worth - and it all has to work perfectly. This special BBC Two programme goes behind the scenes on the £250 million cancer cure – from digging the biggest, widest hole ever to exist in London to the treatment of the first patients in the UK.

star 9.00
3 votes
Directors: Annie Mackinder
The Wizard Who Spat on the Floor

#21 - The Wizard Who Spat on the Floor

Season 1972 - Episode 15

Horizon presents a study of Thomas Alva Edison and his achievements as an inventor.

star 9.00
4 votes
Strangeness Minus Three

#22 - Strangeness Minus Three

Season 1964 - Episode 4

Horizon explores the findings of physicists at Brookhaven, Long Island, New York. Who, after two years and thousands of photographs, have identified a predicted new particle which has a unique characteristic: 'strangeness minus three'.

star 8.87
8 votes
Defeating the Superbugs

#23 - Defeating the Superbugs

Season 2012 - Episode 12

Across the world we are seeing the emergence of bacteria that have gone rogue. These are the superbugs, dangerous bacteria that are becoming resistant to our only defense; antibiotics. Horizon meets the scientists who are tracking the spread of these potential killers around the globe, and discovers the new techniques researchers are developing to help defeat these superbugs.

star 8.87
16 votes
Directors: Diana Hill
What is Reality?

#24 - What is Reality?

Season 2011 - Episode 2

There is a strange and mysterious world that surrounds us, a world largely hidden from our senses. The quest to explain the true nature of reality is one of the great scientific detective stories. Clues have been pieced together from deep within the atom, from the event horizon of black holes, and from the far reaches of the cosmos. It may be that that we are part of a cosmic hologram, projected from the edge of the universe. Or that we exist in an infinity of parallel worlds. Your reality may never look quite the same again.

star 8.72
26 votes
Parallel Universes

#25 - Parallel Universes

Season 2002 - Episode 6

Everything you're about to read here seems impossible and insane, beyond science fiction. Yet it's all true. Scientists now believe there may really be a parallel universe - in fact, there may be an infinite number of parallel universes, and we just happen to live in one of them. These other universes contain space, time and strange forms of exotic matter. Some of them may even contain you, in a slightly different form. Astonishingly, scientists believe that these parallel universes exist less than one millimetre away from us. In fact, our gravity is just a weak signal leaking out of another universe into ours. For years parallel universes were a staple of the Twilight Zone. Science fiction writers loved to speculate on the possible other universes which might exist. In one, they said, Elvis Presley might still be alive or in another the British Empire might still be going strong. Serious scientists dismissed all this speculation as absurd. But now it seems the speculation wasn't absurd enough. Parallel universes really do exist and they are much stranger than even the science fiction writers dared to imagine. It all started when superstring theory, hyperspace and dark matter made physicists realise that the three dimensions we thought described the Universe weren't enough. There are actually 11 dimensions. By the time they had finished they'd come to the conclusion that our Universe is just one bubble among an infinite number of membranous bubbles which ripple as they wobble through the eleventh dimension. Now imagine what might happen if two such bubble universes touched. Neil Turok from Cambridge, Burt Ovrut from the University of Pennsylvania and Paul Steinhardt from Princeton believe that has happened. The result? A very big bang indeed and a new universe was born - our Universe. The idea has shocked the scientific community; it turns the conventional Big Bang theory on its head. It may well be that the Big Bang wasn't really the beginning of everything after all. Time and space all existed before it. In fact Big Bangs may happen all the time. Of course this extraordinary story about the origin of our Universe has one alarming implication. If a collision started our Universe, could it happen again? Anything is possible in this extra-dimensional cosmos. Perhaps out there in space there is another universe heading directly towards us - it may only be a matter of time before we collide.

star 8.67
9 votes