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Joint Probability Calculator

This MicroSim demonstrates how the joint probability of multiple independent breakthroughs compounds multiplicatively. Even when each individual breakthrough seems plausible (10-30% likely), the probability that all of them succeed simultaneously can be vanishingly small.

Quantum computing viability requires not just one breakthrough but several: error rates must drop by orders of magnitude, architectures must scale to millions of qubits, practical error correction must work, useful algorithms must be found, and the result must be economically competitive with classical alternatives. This calculator lets you explore how those individual estimates combine.

Joint Probability Calculator MicroSim

View Joint Probability Calculator MicroSim Fullscreen

Adjust each slider to set your estimate for the probability of that breakthrough succeeding. Watch the funnel visualization narrow as each successive requirement reduces the overall probability. The joint probability updates in real time, showing both the percentage and a "1 in N" odds translation.

Key Takeaways

  • Multiplication shrinks probabilities fast. Five factors at 20% each yield a joint probability of just 0.032% — roughly 1 in 3,125.
  • No single factor dominates. Improving one probability while others remain low has minimal effect on the overall result.
  • Optimism is not enough. Even generous estimates (30-50% per factor) produce joint probabilities well below 1%.
  • This is why skepticism is warranted. The math of joint probability is the strongest argument for questioning quantum computing's commercial timeline.