How to predict the path of a quantum particle. Part 3 in our Quantum Field Theory Series.

You can further support us on Patreon at
Get your own Space Time t­shirt at
Tweet at us! @pbsspacetime
Email us! pbsspacetime [at] gmail [dot] com
Comment on Reddit:

Help translate our videos!

Previous Episode:
The First Quantum Field Theory

There is a fundamental limit to the knowability of the universe. The Heisenberg uncertainty principle tells us that the more precisely we try to define one property, the less definable is its counterpart. Knowing a particle’s location perfectly means its velocity is unknowable. But unmeasured properties are not just uncertain; they are undefined. Quantum mechanics seems to imply that ALL possible properties, paths, or events that could reasonably occur between measurements DO occur. Whether or not this is true, a mathematical description of this crazy idea led to the most powerful expression of quantum mechanics ever devised: Richard Feynman’s path integral formulation.

Written and Hosted by Matt O’Dowd
Produced by Rusty Ward
Graphics by Kurt Ross
Made by Kornhaber Brown (

Comments answer by Matt:

Satya Prakash

Jakub Mintal


Lazarus The adventurer


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

Big Bang
Shane Robinson
David Nicklas
Eugene Lawson
Joshua Davis

Tambe Barsbay
Max Levine
Mayank M. Mehrota
Mars Yentur

Chuck Zegar
Jordan Young
John Hofmann
Joseph Salomone
Martha Hunt
Craig Peterson
Prof. Dr. Kenneth Michael Beck
Science Via Markets

Thanks to our Patreon Gamma Ray Burst Supporters:
Justin Lloyd
Sultan Alkhulaifi
Alex Seto
Conor Dillon
Jared Moore
Michal-Peanut Karmi
Bernardo Higuera
Erik Stein
Daniel Lyons
Kevin Warne
JJ Bagnell
J Rejc
Amy Jie
Avi Goldfinger
John Pettit
Shannan Catalano
Florian Stinglmayr
Yubo Du
Benoit Pagé-Guitard
Nathan Leniz
Jessica Fraley
Loro Lukic
Brandon Labonte
David Crane
Greg Weiss


Feynman’s Infinite Quantum Paths | Space Time

About The Author