We cannot predict whether a given photon will arrive at A or B. All we can predict is that out of 100 photons that come down, an average of 4 will be reflected by the front surface. Does this mean that physics, a science of great exactitude, has been reduced to calculating only the probability of an event, and not predicting exactly what will happen? Yes. That's a retreat, but that's the way it is: Nature permits us to calculate only probabilities. Yet science has not collapsed.

It is impossible to trap modern physics into predicting anything with perfect determinism because it deals with probabilities from the outset.

You can only predict things after they have happened.

Prediction is very difficult, especially about the future.

Predictions are hard, especially of the future

In quantum mechanics...an observation here and now changes in general the 'state' of the observed system....I consider the unpredictable change of the state by a single observation...to be an abandonment of the idea of the isolation of the observer from the course of physical events outside himself.

Chaos theory throws it right out the window. It says that you can never predict certain phenomena at all. You can never predict the weather more than a few days away. All the money that has been spent on long-range forecasting — about half a billion dollars in the last few decades — is money wasted. It’s a fool’s errand. It’s as pointless as trying to turn lead into gold. We look back at the alchemists and laugh at what they were trying to do, but future generations will laugh at us the same way. We’ve tried the impossible — and spent a lot of money doing it. Because in fact there are great categories of phenomena that are inherently unpredictable.

The inability to predict outliers implies the inability to predict the course of history

the only thing that can be predicted is the probability of different events.

...[I]t is simply impossible to predict the effects of lifetime exposure to chemical and physical agents that are not part of the biological experience of man.

when another German scientist, Werner Heisenberg, formulated his famous uncertainty principle. In order to predict the future position and velocity of a particle, one has to be able to measure its present position and velocity accurately. The obvious way to do this is to shine light on the particle. Some of the waves of light will be scattered by the particle and this will indicate its position. However, one will not be able to determine the position of the particle more accurately than the distance between the wave crests of light, so one needs to use light of a short wavelength in order to measure the position of the particle precisely. Now, by Planck’s quantum hypothesis, one cannot use an arbitrarily small amount of light; one has to use at least one quantum. This quantum will disturb the particle and change its velocity in a way that cannot be predicted. Moreover, the more accurately one measures the position, the shorter the wavelength of the light that one needs and hence the higher the energy of a single quantum. So the velocity of the particle will be disturbed by a larger amount. In other words, the more accurately you try to measure the position of the particle, the less accurately you can measure its speed, and vice versa.

"The purpose of a thought-experiment, as the term was used by Schrödinger and other physicists, is not to predict the future - indeed Schrödinger most famous thought experiment goes to show that the "future," on the quantum level, cannot be predicted - but to describe reality, the present world.
Science fiction is not predictive; it is descriptive.
Predictions are uttered by prophets (free of charge), by clairvoyants (who usually charge a fee, and are therefore mor honored in their day than prophets), and by futurologists (salaried). Prediction is the business of prophets, clairvoyants, and futurologists. It is not the business of novelists. A novelist's business is lying. Science fiction is not predictive; it is descriptive.
Predictions are uttered by prophets (free of charge), by clairvoyants (who usually charge a fee, and are therefore mor honored in their day than prophets), and by futurologists (salaried). Prediction is the business of prophets, clairvoyants, and futurologists. It is not the business of novelists. A novelist's business is lying."

Quantum physics might seem to undermine the idea that nature is governed by laws, but that is not the case. Instead it leads us to accept a new form of determinism: given the state of a system at some time, the laws of nature determine the probabilities of various futures and pasts rather than determining the future and past with certainty.

The uncertainty principle signaled an end to Laplace’s dream of a theory of science, a model of the universe that would be completely deterministic: one certainly cannot predict future events exactly if one cannot even measure the present state of the universe precisely! We could still imagine that there is a set of laws that determine events completely for some supernatural being, who could observe the present state of the universe without disturbing it.