What is Quantum Entanglement
Quantum Entanglement can occur when subatomic particles interact with each other. Each subatomic particle has something what we call a spin. Basically how the particle moves through space. The spin can be at any angle and can be clockwise or anticlockwise. When subatomic particles interact and become entangled, there spin and angle is a fuzzy gaze of all possibilities until the particles are measured, according to Bohr. In Bohr's explanation, measuring one of the particles would influence the spin and angle of the other particle, no matter the distance between the two particles, it could be millions of light years but the result would still be instantaneous. Einstein on the other hand believed that result of spins were decided at the time of separation and the distance did not matter because no information needed to pass.
Einstein's Belief
Albert Einstein is believed to be one of the most important people in the history of humanity. Many of his theories are used in different branches of science and some are still being proven correct today. From nuclear energy to GPS all can be linked to Einstein's work in some way. But there was one thing that Einstein could not wrap his head around. Messages travelling faster than the speed of light. Before we get to quantum entanglement, let’s venture down memory lane and understand light.
Speed of Light
The speed of light is a constant to the view of an observer. One of the thought experiments that Einstein conducted was an experiment relating to the speed of light. In Einstein's Theory of Relativity, the speed of light cannot be surpassed in the transferring of information.
Einstein's Thought Experiment
The thought experiment involved, you travelling at the speed of light with a mirror in front of you. As you only see yourself in the mirror because light reflects of the mirror first, and the mirror is travelling at light speed with you, the light would not be able to reach the mirror as it is travelling at the same speed. But if you were to see yourself, an observer would see light travelling at two times the speed of light. Think about it, you see someone travelling at the speed of light and you also see light coming off the mirror so it becomes twice as fast, which destroys Einstein theory as the observer sees light travelling at double speed. After some thought Albert Einstein concluded had when you were travelling at the speed of light with a mirror in front of you, you would be able to see yourself, but travelling at such high speeds would cause everything around you to warp and squeeze. The basic concept that needed to be understood was, according to one of the greatest minds on the planet, messages could not travel faster than light speed.
Niels Bohr
But after the introduction of quantum mechanics, lots of well-known concepts were turned on their hinges, and so was this one. Niels Bohr was in the debate of quantum entanglement, insisted that it is meaningless to assign realism; the 'fact' that the universe is real; to an unobserved location. He believed that quantum entanglement enabled messages to be traveled faster than the speed of light. But before that, let’s understand the concept and experiment.
John Bell
The debate between Einstein and Bohr was unsolvable until John Bell came along. Bell devised an experiment that would prove who was correct between Bohr and Einstein. The experiment involved calculating the probability of the events occurring in Bohr’s prediction and in Einstein’s prediction and then testing to see which probability was correct.
How to Measure Spin?
The machines we use to measure the spin of a particle can measure vertically and horizontally and diagonally. But if the angle of recording is not the same angle on which to particle is spinning, is has a specific chance that it will spin upwards or downwards on the machine depending on the angle. So if the machine is measuring the spin at 60 degrees and the particles are spinning up upwards, there is a ¾ probability that the machine records up and a ¼ probability that the machine records down. This is because 90 degrees, or upwards is closer to 60 degrees, the angle that the machine is measuring at, than 180 degrees for the downwards option. But when two particles are entangled they have no designated spin. There spin is just the opposite of their entangled pair.
When the entangled particles are taken to different locations and they are put through the machines they will automatically a line with machines choice of measuring direction. At that instant the wave function between the two particles collapses, changing the occurrence of the entangled pair. So, if the first particle to be measured results in an upwards spin and from the other side of the universe, the particles being measured on Earth would result in a downwards spin every time.
When the entangled particles are taken to different locations and they are put through the machines they will automatically a line with machines choice of measuring direction. At that instant the wave function between the two particles collapses, changing the occurrence of the entangled pair. So, if the first particle to be measured results in an upwards spin and from the other side of the universe, the particles being measured on Earth would result in a downwards spin every time.
The Experiment
In the experiment, pairs of entangled particles are brought to a location far away. So that the time difference between measuring the particles does not enable light speed to communicate fast enough for the particles choose their spin. Enabling the possibility of quantum mechanics to come into play. Let’s say that there are three angles at which the particles can be measured are but the two machine randomly pick the direction without communicating between each other. If quantum mechanics was right and Einstein was wrong the chance of the particles spin being up would be ½, because before measuring the spin of one of the entangled pair would be in a superposition so it would be in both up and down. In other words, it would just be the opposite of the its entangled pair. But if Einstein was right and quantum mechanics was wrong then the chance of a particle being up would be about 55%.
After conducting this experiment many times it was conducted that quantum mechanics was right and particles could transfer information faster than light with the help of quantum entanglement.
After conducting this experiment many times it was conducted that quantum mechanics was right and particles could transfer information faster than light with the help of quantum entanglement.
Perspective
To put this into perspective, you looking at a specific thing, which incidentally was an entangled particle, could cause the spin of a particle millions of light years away to change and that could potentially cause an explosion or even a black hole.
Don't be careful what you wish for, be careful what you look for...
Don't be careful what you wish for, be careful what you look for...