Quantum mechanics and the stock market Position and momentum CANNOT be determined simultaneously The Uncertainty Principle In 1927, Werner Heisenberg found that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa. We can only know the probable position and momentum of a particle. Investing in an individual stock means you are predicting where its price (position) will be in the future. You are betting that it will reach that price within a given time (momentum). Unless you have insider information, you are really gambling. No one can know a stock's position and momentum in the future. Just like in physics, there is no way to know you'll be in the money in time. Stocks aren't particles, but the analogy holds. We only know where a bunch of particles, like electrons of a charge, are likely to be at a given time. In the same way, we can know only where a bunch of stocks will probably be in the future. In this world, probabilities are the only certainty we have. We are much more likely to earn more in a bunch of stocks than in just one stock over time. Timing is everything. It is more likely that a bunch of stocks will average over 10% for almost every period greater than 5 years. The odds favor this strategy."