Alan Davies attempts to answer the proverbial question: how long is a piece of string? But what appears to be a simple task soon turns into a mind-bending voyage of discovery where nothing is as it seems. An encounter with leading mathematician Marcus du Sautoy reveals that Alan's short length of string may in fact be infinitely long. When Alan attempts to measure his string at the atomic scale, events take an even stranger turn. Not only do objects appear in many places at once, but reality itself seems to be an illusion. Ultimately, Alan finds that measuring his piece of string could - in theory at least - create a black hole, bringing about the end of the world.

Episode Viewers and Ratings

Season 48 Episode 6 of Horizon resulted in a 0.00 rating in the 18-49 demographic.

Horizon Season 48 Episodes...

• s48e01 - Do I Drink too Much?
• s48e02 - The Secret You
• s48e03 - Fix Me
• s48e04 - Who's Afraid of a Big Black Hole?
• s48e05 - Why Do We Talk?
• s48e06 - How Long is a Piece of String?
• s48e07 - How Many People Can Live on Planet Earth?
• s48e08 - The Secret Life of the Dog
• s48e09 - Why Do Viruses Kill?
• s48e10 - Pill Poppers
• s48e11 - Don't Grow Old
• s48e12 - To Infiity and Beyond
• s48e13 - What Makes a Genius?
• s48e14 - Did Cooking Make Us Human?
• s48e15 - Is Everything We Know About The Universe Wrong?

Horizon Show Summary

Horizon is BBC Two's flagship 50-minute science documentary series.

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.

In September 2014 it celebrated its 50th anniversary and it continues to enjoy outstanding critical acclaim.