# Uncertainty principle & Effect before the cause

Is it possible to experience the effect of an event before the cause? And What is the effect of something moving faster than the speed of light? These are interesting questions, I will answer in a while, but before that, let’s look at one aspect of our microscopic world.

Werner Heisenberg (1901-1976), a German physicist who is regarded as one of the creators of modern day quantum mechanics, contributed immensely to its development. The Uncertainty principle, named after Werner Heisenberg, published in 1927 underpins the entire absurdity associated with quantum mechanics.

The uncertainty principle states that we cannot measure the position and speed of a subatomic particle such as an electron at the same time and accurately enough. If we measured the position (location) of an electron accurately, then its speed measurement will be less accurate. Likewise, measuring its speed accurately will result in some error in measuring its position. It is expressed as the product of uncertainties involved in measuring the position and speed of a particle is always either equal to or more than half of Plank’s constant (h). That is, if you multiply the error in calculating the position of an electron with the error in calculating it’s speed, the value is always equal or more than half of Plank’s constant.

There is a fundamental limit upto which we can accurately measure certain things like position and speed, in the microscopic world. This limit cannot be overcome by any kind of scientific instrument, however precise it may be.

It is easy to measure the exact speed and position of a football or your speeding car, based on the simple principle of classical mechanics. You can also measure the speed and position at every moment of a tennis ball tossed into the air, from the time it is thrown up till it hits the ground and stops rolling. This is due to the knowledge we have about the initial conditions and parameters prevailing there.

The tennis ball moves in a deterministic manner. But if you pack several tennis balls or cricket balls into a large metal box which is continuously shaken in a random way, it would be difficult to measure the position and speed of every ball jumping around inside the box.

This is a problem similar to the problem in measuring the exact position and speed of sub atomic particles at the same time.

But the idea of uncertainty in measuring the position and speed of a particle was soon challenged by Einstein, Podolsky and Rosen, who published a paper in 1935, called the EPR paradox

They proposed a thought experiment that questioned the very validity of Heisenberg’s uncertainty principle.

The trial said that one can measure both the position and speed of a particle accurately. They also questioned the explanation of reality based on wave function.

In short, the interpretation of a wave function representation and the Uncertainty principle, lead to a direct conflict with the interpretation provided by the EPR thought experiment.

In a Quantum Entanglement state, the two separated electrons seemed to communicate with each other at a speed faster than light, violating the Causality principle. Causality describes the relation between cause and effect.

By sending a message at a speed faster than light, we end up in a situation where the effect comes before the cause! It is like getting wet even before it starts raining. This is Retrocausality. It is like seeing that some events in the future will impact our present or past exactly in the same way that events in the past affect future events.

There are a dozen interpretations about the nature of quantum mechanics in the scientific world alone, not even considering the philosophical ones.

Uncertainty principle holds good for the quantum world irrespective of the challenge posed by the EPR paradox. Thus, the uncertainty principle puts a severe limitation on our ability to measure accurately the true position and speed of subatomic particles, simultaneously. This remains one of the fundamental truths of the microscopic world where Quantum weirdness reigns.