Lucky-Scramble Forecast: Cumulative Probability of Hitting the Luckiest Scramble
3x3 has 4.3×10^19 states; only 262 (= 1+18+243) are solvable in ≤2 moves. A single random scramble has only ~6×10^-18 chance of landing there. But WCA accumulates many scrambles per year (incl. backups); cumulative-hit probability is P = 1 − (1 − p)^N, monotonically rising with N. Drag the year → see N(Y) → see cumulative probability per depth threshold → see the expected luckiest result.
3x3: Cumulative Hit Probability
Through 2026, WCA has accumulated 6.61M 3x3 scrambles (incl. backups). Cumulative probability of at least one d ≤ K hit across these N is P = 1 − (1 − p)^N. Smaller K → smaller p in the 4.3×10^19 state space → need exponentially larger N.
| Depth K (moves) | # states at d ≤ K | Single-scramble p | P(d≤K hit) @ N=6.61M | N₅₀ (scrambles) | Year reached | Time at d (s, TPS 17) |
|---|---|---|---|---|---|---|
| d ≤ 2 | 262 | 6.1×10^-18 | 4.00×10^-11 | 1.14×10^17 | 2.0×10^6 | 0.27 s |
| d ≤ 5 | 621,649 | 1.44×10^-14 | 9.50×10^-8 | 4.82×10^13 | 41,996 | 0.44 s |
| d ≤ 8 | 1.44B | 3.33×10^-11 | 2.20×10^-4 | 20.80B | 2746 | 0.62 s |
| d ≤ 10 | 251.29B | 5.81×10^-9 | 3.77% | 119.31M | 2056 | 0.74 s |
| d ≤ 12 | 4.37×10^13 | 1.01×10^-6 | 99.9% | 686,214 | 2017 | 0.86 s |
| d ≤ 15 | 9.89×10^16 | 0.229% | ~100% | 303 | 2004 | 1.03 s |
How to read: e.g. d ≤ 2 row — single-scramble prob 6×10^-18 (262 of 4.3×10^19). Need N₅₀ ≈ 1.2×10^17 to have 50% chance of one such hit; that's ~10^14 yr away at WCA's 7.5M scrambles/year cap. That is why "3x3 2-move lucky solve" is not a near-future event but an asymptotic limit. Today the expected luckiest scramble is d ≈ 11.5 with P(d≤12) ≈ 99.9%.
Cumulative Hit Probability vs Year
Each line corresponds to one K threshold. X-axis: log year (2003 → 10^15 yr), Y-axis: P(hit ≤ K). Watch when each line crosses from 0 to 1.
Expected Luckiest Time vs Year (Cross-Event)
Log year vs log seconds. Each line = E[min depth] / TPS_ceil + setup_s per event. Asymptote = k_min_wca / TPS_ceil + setup (fastest physically possible single).
Per-Event Forecast at Selected Year
★ = exact depth distribution; ◐ = partial (exact low / est. high); ~ = approximate. Time = E[min] / TPS_ceil + setup_s.
Methodology
- State space. 3x3 = 4.3252 × 10^19 states; 2x2 = 3,674,160; Pyraminx = 933,120; Skewb = 3,149,280. Their full depth distributions are known.
- Distribution sources. 3x3: cube20.org / Rokicki 2010 (exact d=0..15, est. d=16..20). 2x2: Korf / Pochmann. Pyraminx / Skewb: Jaap Scherphuis. Larger cubes etc.: peak-concentrated approximation.
- Accumulated scrambles N(Y). 2003–2025 from WCA dump (≈28k comps total), 2026+ extrapolated at 5% CAGR capped at 30k comps/year. Per-comp 3x3 scrambles (incl. backups) linearly interpolated 30 → 250 (2003 → 2026). Other events by share factor (4x4 ≈ 0.70 × 3x3).
- Cumulative probability. P(hit at least one d ≤ K in N draws) = 1 − (1 − p_le_K)^N, with p_le_K = ∑_{i≤K} counts[i] / |S|. Implemented via log1p(-p) for numerical stability when p is tiny.
- Expected min E[min]. E[min depth] = ∑_{k=0}^{G-1} (1 − P(min ≤ k)), then clamped to WCA-acceptable minimum (3x3 ≥ 2; 2x2 / Pyraminx / Skewb ≥ 1).
- Execution time. T = E[min] / TPS_ceil + setup_s. TPS_ceil = physiological ceiling (3x3 = 17, dual-hand 22 Hz drum × 50% loss), OH = 10, big cubes 8–12. setup_s = trigger + tap-off 0.10–2.00 s.
- Asymptote (N → ∞). 3x3: 2 moves / 17 TPS + 0.15 s = 0.27 s. 2x2 / Pyraminx / Skewb: 1 move / TPS_ceil + setup ≈ 0.16–0.20 s. These are reachable only when luck + TPS are both maxed; the physical floor (M/TPS+R) is still ~1.5 s and bounds real-comp WRs.
Caveats
- WCA scrambler is uniform sampling, but TNoodle outputs 17–25 move sequences (not filtered for short-solve states). A cumulative hit is mathematical; in practice the cuber would also have to recognize "this is a d=4 state" mid-comp and find a 4-move optimal solution (no algorithm book covers low-d states).
- Recognition + switching + reaction + dual-hand coordination floor (≥ 50 ms StackMat trigger) mean the "d=2 + 17 TPS" 0.27 s is unreachable; the physical floor is ~1.5 s.
- Large cubes / Megaminx / Sq1 / Clock distributions not enumerated; peak-concentrated approximation. Order-of-magnitude reliable, not single-digit.
- FMC / blind not modeled (FMC time = move count; blind is memo-bound, not TPS).