"The Clean Room" is the seventh episode of the American documentary

television series A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite, or cable, excluding breaking news, advertisements, or trailers that are typically placed be ...

'' Cosmos: A Spacetime Odyssey''. It premiered on April 20, 2014, on

Fox Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush''). Twelve sp ...

and aired on April 21, 2014, on National Geographic Channel. The episode explores the methods and processes used to measure the age of the Earth. The episode also pays tribute to

geochemist Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

Clair Patterson Clair Cameron Patterson (June 2, 1922 – December 5, 1995) was an American geochemist. Born in Mitchellville, Iowa, Patterson graduated from Grinnell College. He later received his Ph.D. from the University of Chicago and spent his entire prof ...

(voiced by

Richard Gere Richard Tiffany Gere ( ; born August 31, 1949) is an American actor. He began in films in the 1970s, playing a supporting role in '' Looking for Mr. Goodbar'' (1977) and a starring role in ''Days of Heaven'' (1978). He came to prominence with ...

) in his quest to remove the neurotoxin

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

, from gasoline. The episode's title alludes to Patterson's attempts in sterilizing his lab after realizing that the inconsistent results in his experiments were due to lead contamination. The episode received a 1.4/4 in the 18-49 rating/share, with 3.74 million American viewers watching on

Episode summary

The episode describes how science, in particular the work of

(voiced in animated sequences by

) in the middle of the 20th century, has been able to determine the age of the Earth. Tyson first describes how the Earth was formed from the coalescence of matter some millions of years after the formation of the Sun, and while scientists can examine the formations in rock stratum to date some geological events, these can only trace back millions of years. Instead, scientists have used the debris from meteor impacts, such as the

Meteor Crater Meteor Crater, or Barringer Crater, is a meteorite impact crater about east of Flagstaff and west of Winslow in the desert of northern Arizona, United States. The site had several earlier names, and fragments of the meteorite are officia ...

in Arizona, knowing that the material from such meteors coming from the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, c ...

would have been made at the same time as the Earth. Tyson then outlines the work Patterson did as a graduate under his adviser

Harrison Brown Harrison Scott Brown (September 26, 1917 – December 8, 1986) was an American nuclear chemist and geochemist. He was a political activist, who lectured and wrote on the issues of arms limitation, natural resources and world hunger. During Worl ...

to provide an accurate count of lead in

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

particles from Meteor Crater, and to work with similar results being collected by George Tilton on uranium counts; with the established

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of uranium's radioactive decay to lead, this would be used to estimate the age of the Earth. Patterson found that his results were contaminated by lead from the ambient environment, compared to Tilton's results, and required the construction of the first ultra-high

cleanroom A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. It is well isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientif ...

to remove all traces of environmental lead. With these clean results, Patterson was able to estimate the age of the Earth to 4.5 billion years. Tyson goes on to explain that Patterson's work in performing lead-free experiments directed him to investigate the sources for lead. Tyson notes how lead does not naturally occur at Earth's surface but has been readily mined by humans (including the

Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediter ...

), and that lead is poisonous to humans. Patterson examined the levels of lead in the common environment and in deeper parts of the oceans and Antarctic ice, showing that lead had only been brought to the surface in recent times. He would discover that the higher levels of lead were from the use of

tetraethyllead Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb( C2H5)4. It is a fuel additive, first being mixed with gasoline beginning in the 1920s as a patented octane rating booster that ...

in leaded gasoline, despite long-established claims by Robert A. Kehoe and others that this chemical was safe. Patterson would continue to campaign against the use of lead, ultimately resulting in government-mandated restrictions on the use of lead. Tyson ends by noting that similar work by scientists continues to be used to help alert mankind to other fateful issues that can be identified by the study of nature.

Reception

The episode's premiere on

brought a 1.4/4 in the 18-49 rating/share, with an audience of 3.74 million American viewers. It placed fourth and last in its timeslot behind ''

The Good Wife ''The Good Wife'' is an American legal and political drama television series that aired on CBS from September 22, 2009, to May 8, 2016. It focuses on Alicia Florrick, the wife of the Cook County State's Attorney, who returns to her career in l ...

'', ''In My Dreams (film), In My Dreams'', and ''Believe (TV series), Believe''; and eighth out of seventeenth for the night. Jennifer Ouellette of the ''Los Angeles Times'' called it "the strongest, most coherent, and riveting episode yet."

References

External links

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The Clean Room
at National Geographic Channel {{DEFAULTSORT:Clean Room Cosmos: A Spacetime Odyssey episodes Television episodes directed by Brannon Braga