CUT IT. HIGHER?

What will you explore?

Cohen and Horowitz, 1991

Changing one connection can reorganize an entire network.

How does it work?

Watch a 90-second cinematic explanation, or explore a story that pauses so you can change its central mechanism. Inspect the source evidence, compare outcomes and resume the narration. This free Lesson Worlds adaptation needs no account or download; younger learners may want help from a parent or teacher.

Inside the cinematic story

1. CUT IT. HIGHER?

   CUT IT. HIGHER?

2. Two springs, three strings

   Two springs, three strings

3. One load becomes two paths

   One load becomes two paths

   Take control: Which paths carry the load? Connector intact · Connector cut

4. A higher equilibrium

   A higher equilibrium

5. When the cut does nothing

   When the cut does nothing

   Take control: Does every cut raise the weight? Short: .375 m · Long: .875 m

6. Follow the whole network

   Follow the whole network

Discuss the evidence

Before starting, explain what you think this claim means: Changing one connection can reorganize an entire network. After exploring, choose one stage above and describe what its model helps you see. Separate what you observed in the adaptation from what the original researchers measured.

Read the original publication for its methods, evidence and limitations. Ask which part of the explanation the interactive model leaves out, and what additional evidence you would need to test the claim yourself.

Original reconstruction of the ideal mechanical network in Cohen and Horowitz (1991), Figure 1. Massless Hookean springs have zero rest length; strings are perfectly inelastic. Equilibrium values use k=1 N/m, load=0.5 N, safety strings=1 m and linking string L=0.375 or 0.875 m. The two chosen cases are solved analytically: intact X=2F/k+L when safety strings are slack; cut X=1+F/(2k). At L=0.875 the intact safety strings are already taut and the linking string slack, so cutting it changes no equilibrium. Geometry scales lengths by three; small lateral separation and decorative coils do not reproduce literal zero-rest-length components. Reconfiguration, cut ends and settling animation are prescribed, not a transient dynamics solver, experimental footage or measurements. No universal benefit from removing links, no free energy, and no claim that real roads or electrical grids follow this exact example.

Original research

Paradoxical behaviour of mechanical and electrical networks

Joel E. Cohen and Paul Horowitz · Nature 352, 699–701 (22 August 1991) · 1991

Educational adaptation by Lesson Worlds. Not affiliated with the authors, Rockefeller University, Harvard University or Nature. The original publication may have its own access terms.