Einstein's Box
Requires a Wolfram Notebook System
Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.
This thought experiment proposed by Albert Einstein in 1906 considers a box of mass and length in which a quantity of radiant energy is emitted from one end toward the other. The box moves a distance (exaggerated in the picture) in a time with a velocity in the opposite direction to the photons, which carry the equivalent of a mass . The momentum carried by the radiation is given by . Assuming conservation of momentum and energy (for the case ) leads to Einstein's celebrated equation , applicable, at least, to photons.
Contributed by: Enrique Zeleny (May 2009)
Open content licensed under CC BY-NC-SA
Snapshots
Details
A. Einstein, Ann. Phys., 20, 1906 pp. 627–633.
Permanent Citation
"Einstein's Box"
http://demonstrations.wolfram.com/EinsteinsBox/
Wolfram Demonstrations Project
Published: May 29 2009