Russian Roulette — Spin or Not?
The problem
A six-shot revolver has two bullets loaded in adjacent chambers. The other four are empty.
Your opponent:
- Spins the cylinder.
- Pulls the trigger at himself. Click. Empty.
- Hands you the gun and offers a choice: spin again before your turn, or just pull the trigger.
What should you do?
Tempting (but wrong)
Two common wrong intuitions:
- "Spin — reset the randomness." Feels like spinning is "safer." It actually throws away a piece of information.
- "Same either way — two of six chambers are loaded." Treats the gun as memoryless. But the bullets are placed consecutively, so the empty click is informative about which chamber comes next.