# Heisenbergs Uncertainty Principle and Einstein and Bohrs Arguments

Quoted from one of the greatest scientists of the 20th century, Albert Einstein, “… god does not play dice.” He gave this response when Werner Heisenberg proposed the uncertainty principle, Einstein said that statement thinking the natural world does not go by probabilities. Heisenberg however, said we can not know the exact position and speed of an electron at the same time; we can only know the probability of one and the exact number of the other. Therefore, he reasoned, if you know the exact speed of the electron then the position is only a probability, not an exact position.

In quantum mechanics a particle is described as a wave instead of a particle. The position of the particle is simply where the wave is concentrated, and the speed of the particle is the wavelength divided by the frequency. The position of the particle is unknown to the degree of the amplitude of the wave. If you know anything about waves, then you should know the frequency is how many times the crest of the wave passes a point in a second. The amplitude of the wave is how far the crest extends out, finally the wave length is the length from one trough to the next, a trough is the opposite of a crest.

Waves only have a definite position when it is concentrated at one point, which means the wave length cannot be defined. On the contrary, waves only have a definite speed when there is a distinct crest and trough, which means the position cannot be exactly determined. Consequently, in quantum dynamics there is no states particles can be in that give you both the exact position and velocity, which gave rise to the uncertainty principle.

Einstein proposed a few thought experiments to disprove the uncertainty principle, the first thought experiment goes as follows. Consider a particle passing through a slit of width d. The slit introduces an uncertainty in momentum of approximately h/d because the particle passes through the wall. But let us determine the momentum of the particle by measuring the recoil of the wall. In doing so, we will find the momentum of the particle to arbitrary accuracy by conservation of momentum. Bohr’s response to this thought experiment was to some extent of the wall that we are measuring the recoil from is quantum dynamic also, so the uncertainty that the wall produces is equal if not more then the uncertainty if we measured the particle in more conventional ways.

Soon after Einstein proposed another thought experiment to disprove the uncertainty principle. This one is called Einsteins Box which goes as follows. Consider a box filled with light. The box has a shutter, which opens and quickly closes by a clock at a precise time, and some of the light escapes. We can set the clock so that the time that the energy escapes is known. To measure the amount of energy that leaves, Einstein proposed weighing the box just after the emission. The missing energy will lessen the weight of the box. If the box is mounted on a scale, it is naively possible to adjust the parameters so that the uncertainty principle is violated. After Bohr considered this for a while, he realized if the energy of the box is known, then the time in which the shutter opens and closes is uncertain because the presence of a gravitational field alters time slightly and can account for the uncertainty that is required in this situation.

Einstein never disproved the uncertainty principle which he despised, and the ironic thing about all this is Einstein is credited to be the father of quantum mechanics and dynamics even though he did not believe in its accuracy. Even though one of our greatest scientist disapproved this branch of physics, it is thought to be correct for most scientist. It is still an active area of research and development and is now an important branch to explain the natural world. So the question seems to be answered, god might play dice.