The Impossibility of Perpetual Motion Machines

You can learn more about CuriosityStream at

PBS Member Stations rely on viewers like you. To support your local station, go to

Check out the new Space Time Merch Store!

Support Space Time on Patreon

See Matt in NYC at Caveat March 7th at 9pm:

Bad ideas come and go in physics. But there’s one bit of nonsense that is perhaps more persistent than all others: the perpetual motion machine. No working perpetual motion machine has ever been experiment verified. All break the laws of thermodynamics. In fact, we classify based on WHICH law of thermodynamics they break. We have perpetual motion machines of the first kind - they violate energy conservation - they pump more energy out than they need to keep running. This includes most of the historical devices. Then there are machines of the second kind - they’re a bit more subtle in their wrongness because break the second law of thermodynamics - extracting energy by reversing entropy. Many modern “free-energy” devices fall into this category. Now the best modern designs are by you - answers to our recent challenge question, which we’ll get to at the end. But first let’s take a look at examples of what other people came up with - this’ll be a fun little journey through some pretty terrible science.

Challenge Winners Please Email pbsspacetime@gmail.com, with your choice of product from the Merch Store ()

Connor Grey

Creepy Magician

Alex Taylor

Adrien Romeo

Epsilon Centauri

Enoae Andrei

Tweet at us! @pbsspacetime

Facebook: facebook.com/pbsspacetime

Email us! pbsspacetime [at] gmail [dot] com

Comment on Reddit

Help translate our videos!

Sound Waves from the Beginning of Time

Hosted by Matt O'Dowd

Written by Matt O'Dowd

Graphics by Kurt Ross

Directing by Andrew Kornhaber

Designing a perpetual motion machine has a very long history and became quite the craze from the middle ages through the renaissance. The first well-documented design for a perpetual motion machine was from the 12th century. Bhāskara's wheel, named after the Indian mathematician, was embedded with tubes of mercury that would flow from back and forth as the wheel turned. Other types of over-balance wheels followed through to the Renaissance and worked on the same principle. There were also designs that employed the magical-seeming lodestones – magnets. For example, this ramp in which a ball is pulled to the top by a magnet before falling through a hole and rolling to the bottom again. Then there are the self-pumping waterwheels or self-blowing windmills.

Special thanks to our Patreon Big Bang, Quasar and Hypernova Supporters:

Big Bang:

Anton Lifshits

coolascats

David Nicklas

Fabrice Eap

Juan Benet

Justin Lloyd

Tim Davis

Quasar:

James Flowers

Mark Rosenthal

Tambe Barsbay

Vinnie Falco

Hypernova:

chuck zegar

Danton Spivey

Donal Botkin

Edmund Fokschaner

Jens Theisen

John Hofmann

Jordan Young

Joseph Salomone

kkm

Mark Heising

Matthew O'Connor

Thanks to our Patreon Gamma Ray Burst Supporters:

Alexey Eromenko

Antonio Ruiz

Bradley Jenkins

Brandon Labonte

Buruk Aregawi

Carlo Mogavero

Daniel Lyons

David Behtala

David Crane

David Schmidt

Dustan Jones

Geoffrey Short

Greg Weiss

Jack Frosch

James Hughes

James Quintero

Jinal Doshi

JJ Bagnell

John Webber

Jon Folks

Jonah

Joseph Emison

Josh Thomas

Kenneth F Leonard

Kevin Warne

Kyle Hofer

Malte Ubl

Mark Vasile

Nathan Hitchings

Nicholas Rose

Nick Virtue

Ratfeast

Richard Broman

Scott Gossett

Sigurd Ruud Frivik

Tim Crookham

Tim Stephani

Tommy Mogensen

سلطان الخليفي