Drones are transforming our world. We use them to deliver our medicines, clean our skyscrapers and even fight fires. But there is a dark side to this airborne revolution, from a shocking rise in drone-plane near misses above our heads to last year's sustained drone disruption at Gatwick – Britain's second largest airport – that ruined the Christmas plans of 140,000 people and cost millions. 　　In this documentary, high-risk specialist and former Royal Marine Aldo Kane sets out to investigate the scale of the threat drones pose to our airports and skies – from rogue hobbyists to determined terrorist attacks. He explores what technologies are out there that governments and the aviation industry can turn to, to keep our skies safe. 　　Aldo begins his journey by examining the dangers drone collisions pose to planes. He travels to one of the UK's leading impact test facilities to join a team firing drones into a plane wing at 250mph to simulate a mid-air impact and assess the damage. He then uncovers a heart-stopping drone-plane near miss that took place over the skies of London. 　　Next Aldo investigates the science behind new technology leading drone manufacturers are implementing into their machines to try and keep drones and planes apart. But we see this is far from a fail-safe solution – especially if the drone operator is determined to cause trouble. 　　Aldo searches for a way to remove dangerous drones from the sky and explores the technological options available. From the crude - shooting a drone down with a high-calibre sniper rifle - to the sophisticated - a cutting-edge radio frequency detection system being trialled by London Southend Airport. 　　But it is not just rogue hobbyists that we need our drone systems to defend us against. Aldo meets terrorism expert James Rogers to discover how organisations like ISIS are increasingly weaponising drones and how fast-evolving drone technologies – like FPV (first person view) drone flying – are exceptionally difficult to counter. He then hears harrowing evidence from British fighter Macer Gifford, who describes the first-hand experience of coming under daily attacks from ISIS drones in Syria during the battle for Raqqa. 　　Fortunately, in the UK we have sophisticated military-grade counter-drone technology available to battle a potential weaponised attack. Aldo trials one version of a defence system that was used by the RAF during the Gatwick crisis. We see how its pinpoint electronic jamming attack can remove a drone from the sky in seconds. 　　But even this technology might not be enough to keep us safe in the future, as drone technology continues to advance. Aldo heads to Philadelphia to meet a company developing a new generation of 'smart drones', and he puts this amazing tech through its paces. These intelligent drones fly fully automatically, mapping their surroundings and making their own decisions. This means they don't rely on an external operator signal for control, and so they can’t be stopped by jamming-based defence systems. 　　For the last leg of his journey, Aldo heads to Dallas to test out a high-powered laser mounted on a highly mobile dune buggy that can literally melt drones out of the sky. It is one of the few defence systems that could combat the futuristic threat of fully automatic drones. Will we one day be seeing systems like this rolled out around the UK’s airports and other vulnerable locations? And who is going to pay for it?

Drones are transforming our world. We use them to deliver our medicines, clean our skyscrapers and even fight fires. But there is a dark side to this airborne revolution, from a shocking rise in drone-plane near misses above our heads to last year's sustained drone disruption at Gatwick – Britain's second largest airport – that ruined the Christmas plans of 140,000 people and cost millions. 　　In this documentary, high-risk specialist and former Royal Marine Aldo Kane sets out to investigate the scale of the threat drones pose to our airports and skies – from rogue hobbyists to determined terrorist attacks. He explores what technologies are out there that governments and the aviation industry can turn to, to keep our skies safe. 　　Aldo begins his journey by examining the dangers drone collisions pose to planes. He travels to one of the UK's leading impact test facilities to join a team firing drones into a plane wing at 250mph to simulate a mid-air impact and assess the damage. He then uncovers a heart-stopping drone-plane near miss that took place over the skies of London. 　　Next Aldo investigates the science behind new technology leading drone manufacturers are implementing into their machines to try and keep drones and planes apart. But we see this is far from a fail-safe solution – especially if the drone operator is determined to cause trouble. 　　Aldo searches for a way to remove dangerous drones from the sky and explores the technological options available. From the crude - shooting a drone down with a high-calibre sniper rifle - to the sophisticated - a cutting-edge radio frequency detection system being trialled by London Southend Airport. 　　But it is not just rogue hobbyists that we need our drone systems to defend us against. Aldo meets terrorism expert James Rogers to discover how organisations like ISIS are increasingly weaponising drones and how fast-evolving drone technologies – like FPV (first person view) drone flying – are exceptionally difficult to counter. He then hears harrowing evidence from British fighter Macer Gifford, who describes the first-hand experience of coming under daily attacks from ISIS drones in Syria during the battle for Raqqa. 　　Fortunately, in the UK we have sophisticated military-grade counter-drone technology available to battle a potential weaponised attack. Aldo trials one version of a defence system that was used by the RAF during the Gatwick crisis. We see how its pinpoint electronic jamming attack can remove a drone from the sky in seconds. 　　But even this technology might not be enough to keep us safe in the future, as drone technology continues to advance. Aldo heads to Philadelphia to meet a company developing a new generation of 'smart drones', and he puts this amazing tech through its paces. These intelligent drones fly fully automatically, mapping their surroundings and making their own decisions. This means they don't rely on an external operator signal for control, and so they can’t be stopped by jamming-based defence systems. 　　For the last leg of his journey, Aldo heads to Dallas to test out a high-powered laser mounted on a highly mobile dune buggy that can literally melt drones out of the sky. It is one of the few defence systems that could combat the futuristic threat of fully automatic drones. Will we one day be seeing systems like this rolled out around the UK’s airports and other vulnerable locations? And who is going to pay for it?

For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of white-hot metal and a giant forest of crystals make up a metal core the size of the Moon. 　　Horizon follows scientists who are conducting experiments to recreate this core within their own laboratories, with surprising results.

For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of white-hot metal and a giant forest of crystals make up a metal core the size of the Moon. 　　Horizon follows scientists who are conducting experiments to recreate this core within their own laboratories, with surprising results.

如果你被问到“你知道现在的时间吗”，是否会觉得这是一个太过简单的问题？看看腕上的手表，或是翻出手机，精确到分秒的时间就能被轻易知晓。然而今天，粒子物理学家布莱恩·考克斯教授也如此问到。布莱恩探访了墨西哥的古玛雅金字塔，在那里古玛雅人是靠建神殿来计时的。他惊人地发现，符合地球本身规律的“时间”，从来都不是一天24小时。那么这个我们早已习以为常的“公理”，到底是个物质周期变化的规律，还是我们对于时间和空间认知上的一种错觉呢？ 　　此次BBC地平线系列纪录片的摄制组，将跟随布莱恩教授的脚步，从时间的起点开始入手研究，走访了多个支持“弦理论”的国度，并研究了时间的极限，试图解开这个抽象概念背后的神奇奥秘。

如果你被问到“你知道现在的时间吗”，是否会觉得这是一个太过简单的问题？看看腕上的手表，或是翻出手机，精确到分秒的时间就能被轻易知晓。然而今天，粒子物理学家布莱恩·考克斯教授也如此问到。布莱恩探访了墨西哥的古玛雅金字塔，在那里古玛雅人是靠建神殿来计时的。他惊人地发现，符合地球本身规律的“时间”，从来都不是一天24小时。那么这个我们早已习以为常的“公理”，到底是个物质周期变化的规律，还是我们对于时间和空间认知上的一种错觉呢？ 　　此次BBC地平线系列纪录片的摄制组，将跟随布莱恩教授的脚步，从时间的起点开始入手研究，走访了多个支持“弦理论”的国度，并研究了时间的极限，试图解开这个抽象概念背后的神奇奥秘。

Around the world, a new generation of astronomers are hunting for the most mysterious objects in the universe. Young stars, black holes, even other forms of life. 　　They have created a dazzling new set of super-telescopes that promise to rewrite the story of the heavens. 　　This film follows the men and women who are pushing the limits of science and engineering in some of the most extreme environments on earth. But most strikingly of all, no-one really knows what they will find out there.

Around the world, a new generation of astronomers are hunting for the most mysterious objects in the universe. Young stars, black holes, even other forms of life. 　　They have created a dazzling new set of super-telescopes that promise to rewrite the story of the heavens. 　　This film follows the men and women who are pushing the limits of science and engineering in some of the most extreme environments on earth. But most strikingly of all, no-one really knows what they will find out there.

Horizon is BBC Two's flagship 50-minute science documentary series. In September 2004 it celebrated its 40th 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.

Horizon is BBC Two's flagship 50-minute science documentary series. In September 2004 it celebrated its 40th 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.