The probability that the stone will go up(against gravity) is zero. The physics give a poisson error distribution. That means the measurement + error will always be greater than zero and in the direction of the field. Also, the probability that a particle, or quanta will traverse an infinite barrier is zero.
"Not by Chance"
It's not a discussion. It's a $10 book. A worthwhile treatise on the subject would be worth considerably over $200. For $10 that's what I would expect-the equivalent of stones falling upward. For your information there is not enough known to even begin plugging in believable numbers. That's because their aren't enough known details.
"It's pretty hard to evolve "gradually over a long time" from 22 (or 24)."
Hard notwithstanding, it happened.
I guess I wonder what degrees you have.
The number I seem to recall is 1 in 10 to the -23. The probability that spontaneous evolution might occur is lower.
ML/NJ