Download video: Uncanny Relativity: Underpinnings Of Length Contraction

Channel: UncertaintyDrive


TIP: Right-click and select "Save link as.." to download video

Initializing link download... Initializing link download.....

Special relativity: Flashing ring clocks expose the deep connection between relativistic length contraction and relativity of simultaneity. Visually.

If you find this video interesting and/or useful, please comment/like/subscribe.

Special relativity challenges our deeply seated perceptions of simple mechanical motion. Once obvious and intuitive assumptions about space, time, and the appearance of moving objects are suddenly superseded by highly counterintuitive concepts: time dilation, space contraction, relativity of simultaneity. The new picture is perplexing and difficult to visualize when we lack hands-on experience with relativistic motion. But can we rebuild an adequate intuition of space and time in a relativistic context?

“Uncanny Relativity” is intended as a collection of easy to understand animations meant to demonstrate some finer points of relativistic length contraction, time dilation, and relativity of simultaneity. It assumes minimal familiarity with these concepts and attempts to revive a more intuitive view of relativistic motion and space-time.

The 1st installment, “The Underpinnings Of Length Contraction”, explores the relativistic phenomenon in a simple but unconventional context that exposes its close connections to relativity of simultaneity and time dilation. It employs what may be called a space-time tomography of relativistic motion in order to illustrate why we can say that relativistic objects are perceived in genuine “space-time cross-sections” across finite intervals of their proper-time. It does not provide a “proof” of length contraction, but rather examines its relation to “space-time cross-sections”.

An Appendix (13:09) outlines mathematical details for those interested. The timing of individual slides is rather brief (10s) in order to limit file size. Please pause to view properly or read at leisure here:

Math details also available now in pop-up annotations. If interested, hover over the blue text boxes to reveal content.
English subtitles transcribed. Note: Older browsers may not display special characters in annotations. If you see empty squares and/or boxes in annotated equations, please ignore and use instead the slides at

A brief version is available here:
Underpinnings Of Length Contraction - Brief,

Also available in the Uncanny Relativity series:

Length Contraction Paradox,

Length Contraction Paradox - Brief,

Further reading on special relativity and related topics:
On Wikipedia:
Theory of relativity,
Length contraction,
Relativity of simultaneity,
Time dilation,
Lorentz transformation,
Spacetime diagram,

On Youtube:
Cassiopeia Project's Relativity, (also as Einstein's Theory Of Relativity Made Easy,
Albert Einstein's Theory of Relativity, (Albert Einstein's Theory of Relativity)
Relativity Train,
… and a huge multitude of other wonderful contributions.

©Uncertainty Drive 2014-2015: The “Uncanny Relativity” Project uses original animations and narration, as well as original soundtracks developed using Apple's GarageBand and royalty-free loops and sound effects provided therein (©Apple Inc. 2002-2015).