🤖 AI Summary
Overview
This episode explores the counterintuitive physics of a mechanism that shrinks when stretched, linking it to Braess's Paradox—a phenomenon where adding resources to a network can worsen its performance. The discussion spans mechanical systems, traffic flow, and broader implications for networks like power grids and the internet.
Notable Quotes
- It feels like it violates physics. It’s just so counterintuitive that the displacement is in the other direction to the force.
– Derek Muller, on the shrinking mechanism.
- Removing the road would actually make the traffic better. It’s just like cutting the green rope from before.
– Derek Muller, explaining Braess's Paradox.
- It’s like a balloon that deflates when you inflate it. That would be the equivalent, but it’s not there yet.
– Bas Overvelde, on future possibilities for counter-snapping mechanisms.
🪢 The Spring Paradox
- A mechanism with springs and ropes demonstrates a paradox: cutting a rope under tension causes the weight to rise instead of fall.
- This occurs because the springs transition from a series
configuration (greater extension) to a parallel
configuration (less extension), causing contraction.
- The setup relies on slack ropes to create the illusion that the weight will drop, but precise slack length is critical for the effect.
🚦 Braess's Paradox in Traffic
- Braess's Paradox explains how adding a road to a traffic network can increase congestion.
- A real-world example occurred during New York’s 1990 Earth Day, where closing 42nd Street reduced traffic by 20%.
- The paradox arises because individual drivers make rational decisions to minimize their own travel time, which collectively worsens outcomes for everyone.
🔌 Broader Implications of Braess's Paradox
- The paradox applies to various networks, including power grids, where adding capacity can destabilize the system or cause blackouts.
- It also affects systems like food chains, blockchain networks, and the internet, where adding elements can degrade overall performance.
- Mathematicians have modeled cities to identify redundant roads that could be removed to improve traffic flow.
🌀 Snapping vs. Counter-Snapping
- Traditional snapping occurs when materials suddenly give way under force, like an umbrella flipping in the wind.
- Counter-snapping, by contrast, causes a mechanism to contract when stretched, defying intuition.
- This behavior is achieved by combining components that individually behave like springs but collectively exhibit this unique property.
🔬 Applications and Future Potential
- Counter-snapping mechanisms can switch between states without changing length, enabling control over stiffness and natural frequency.
- This could be used to prevent excessive vibrations in structures by dynamically shifting resonance points.
- Researchers are exploring other applications, such as materials that decrease in volume when pressurized, though these concepts remain in early stages.
AI-generated content may not be accurate or complete and should not be relied upon as a sole source of truth.
📋 Video Description
How an unlikely physics paradox controls these counterintuitive structures. Use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off.
If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically - https://ve42.co/SnatomsV
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A huge thank you to Paul Ducarme and Bas Overvelde at AMOLF for showing us around.
Check out their research on counter-snapping structures here - https://ve42.co/CounterSnapping
For more on Braess’s Paradox, check out these great videos by Up and Atom (https://youtu.be/cALezV_Fwi0) and Steve Mould (https://www.youtube.com/watch?v=Cg73j3QYRJc)
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0:00 What happens if you cut this rope?
1:41 The Spring Paradox
4:59 New York’s Perplexing Discovery
6:29 Road Networks and Traffic Flow
8:40 Braess’s Paradox
14:29 Snapping
17:16 This object shrinks when you stretch it
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References:
Ducarme, P., Weber, B., Hecke, M. van, & Johannes. (2025). Exotic mechanical properties enabled by countersnapping instabilities. Proceedings of the National Academy of Sciences - https://ve42.co/CounterSnapping
Braess's Paradox via Wikipedia - https://ve42.co/BraessWiki
Braess, D., Nagurney, A., & Wakolbinger, T. (2005). On a Paradox of Traffic Planning. Transportation Science - https://ve42.co/Braess2005
Schäfer, B., Pesch, T., Manik, D., Gollenstede, J., Lin, G., Beck, H.-P., … Timme, M. (2022). Understanding Braess’ Paradox in power grids. Nature Communications - https://ve42.co/Schafer2022
Kolata, G. (1990). What if They Closed 42d Street and Nobody Noticed? New York Times - https://ve42.co/Kolata1990
Youn, H., Gastner, M. T., & Jeong, H. (2008). Price of Anarchy in Transportation Networks: Efficiency and Optimality Control. Physical Review Letters - https://ve42.co/Youn2008
Nicolaou, Z. G., & Motter, A. E. (2012). Mechanical metamaterials with negative compressibility transitions. Nature Materials - https://ve42.co/Nicolaou2012
Counter-Snapping replication package - https://ve42.co/CSPackage
Images & Video:
Earth Day Festivities via VHS Music Rarities - https://www.youtube.com/watch?v=0awPgHjn2nY
Earth Day Speeches - https://www.youtube.com/watch?v=RMDI3kXpeQ8
1990s New York via NYC Nostalgia - https://www.youtube.com/watch?v=0YaFxTw0VqM
42nd Street Closure via Trainluvr - https://www.youtube.com/watch?v=gELde63Fzio
42nd Street Traffic Operator - https://ve42.co/NYCTraffic
Dietrich Braess via opc.mfo.de - https://ve42.co/BraessOPC
Dietrich Braess via Wikipedia - https://ve42.co/BraessWikiPic
Belt Buckle via Mingda Hardware - https://ve42.co/BeltBuckle
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Special thanks to our Patreon supporters:
Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, armedtoe, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Charles Ian Norman Venn, Dave Kircher, David Johnston, David Tseng, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Jeromy Johnson, Jon Jamison, JT, Juan Benet, Keith England, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Robert Oliveira, Sam Lutfi, Tj Steyn, TTST, Ubiquity Ventures, and wolfee
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Writers: Gregor Čavlović & Derek Muller
Producer & Director: Gregor Čavlović
Editors: James Stuart & Trenton Oliver
Camera Operators: Sander Mook, Dylan Meanwell, Fabio Albertelli, Casper Mebius & Gregor Čavlović
Animator: Fabio Albertelli
Illustrator: Jakub Misiek
Additional Editor: Peter Nelson & James Horsley
Researchers: Darius Garewal & Gabe Strong
Thumbnail Designers: Ren Hurley & Ben Powell
Production Team: Rob Beasley Spence, Tori Brittain & Matthew Cavanagh
Executive Producers: Derek Muller & Casper Mebius
Additional video/photos supplied by Getty Images, Pond5.
Music from Epidemic Sound