Sci-Tech · 13 Aug 2026

Deepak Dhar Abelian Sandpile Dirac Medal

With reference to the Abelian sandpile model, consider the following pairs:

  1. Per Bak, Chao Tang, Kurt Wiesenfeld - Originated the 1980s concept of self-organised criticality
  2. Deepak Dhar - Developed the exact mathematical framework proving a toppling sandpile always settles into the same final configuration
  3. Abelian property - Refers to outcomes depending critically on the specific sequence in which sand grains cascade
A1 only
B1 and 2 only
C2 and 3 only
D1, 2 and 3
This question is based on: The Work That Won Deepak Dhar the Dirac Medal
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About this question

Why in news

Deepak Dhar was awarded the 2026 Dirac Medal for developing the Abelian sandpile model, a framework now applied to earthquakes, forest fires, neural network bursts and financial market fluctuations.

Why for UPSC

This tests the precise technical meaning of a named property ("Abelian") rather than just recognising the scientist's name - UPSC Sci-Tech questions often hinge on whether a specific term means what it sounds like it should mean.

Prelims summary

Deepak Dhar's Abelian sandpile model (building on Bak-Tang-Wiesenfeld's self-organised criticality) proved a toppling sandpile's final state is independent of grain-cascade sequence - work that won him the 2026 Dirac Medal.

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