This post has me very animated, it took me a couple of days to write it and try to make everything look so good, enjoy it.
The physics that studies and explains the phenomena that occur at a subatomic level, where the nucleus of the atoms is, the elementary particles and everything small that is impossible to see with our eyes, even if we are using a microscope, that physics is called quantum physics. And, the basic mathematical theory that explains the movements and relationships in this field is called quantum mechanics. In short, quantum physics is responsible for the theoretical part at the subatomic level, and quantum mechanics is responsible for the mathematical part at the subatomic level. Well, since we are clear that quantum physics is different from quantum mechanics, I can freely use these terms without any confusion.
For many years, man was always interested in knowing the why of things, knowing how to explain where certain phenomena come from and how is their behavior, man is curious in nature, this led him to investigate to find a satisfactory answer. In the 19th century, the scientist Max Planck asked himself: Why does the color of light change when the filament of a light bulb heats up?, people of the time did not care in the slightest why the light of a light bulb changes, the important thing was that electricity existed and that it could illuminate homes, businesses, streets and everything we want.
The invention of the electric bulb opened the doors to the birth of quantum mechanics, Max Planck decided to look for the relationship between color and temperature. For this, Planck and his colleagues decided to conduct an experiment to study the radiation of a black body, they created a special tube that they could heat to a very precise temperature and thus be able to measure the color or the frequency of the light that was produced.
Planck drew his own conclusions: The energy was absorbed and emitted in energy quanta proportional to the frequency of the light it radiates, multiplied by the Planck constant which has a numerical value of 6.63x10^-34 J.s, this equation is summarized in E = hf. Planck devised a new way of imagining energy, either in the form of packages or as he said "how many", yes friends, the energy is quantized in packages discreetly. In the subatomic world energy is studied in a quantized way, even, the quantum physics comes from the name that Planck put to his discovery: energy quanta
A black body is a theoretical or ideal object that absorbs all the light and all the radiant energy that falls on it. None of the incident radiation is reflected or passes through the black body.
Ideal black body | Source
In the nineteenth century, Heinrich Hertz serendipitously discovered the photoelectric effect, Hertz experienced a completely new and disconcerting phenomenon: "The spark between two metal spheres became brighter, the electric discharge increased, when one of them was illuminated with ultraviolet light". But, unfortunately, Hertz died at 36 years of age and could not finish deciphering what happened with the photoelectric effect.
Serendipity: To refer to the ability of a subject to recognize that he has made an important discovery even though it has no relation to what he is looking for, that is, serendipity is to find something that you were not looking for.
In 1905, Albert Einstein came to make history, he devised a new theory to explain the photoelectric effect, he maintained intrinsically that: "We must forget all ideas that light is a wave and think it is a stream of tiny particles." Einstein had changed the way we see light as a wave, now we had to study it as a particle. To describe it he used the term that Planck used previously: how many, what we nowadays know as photon, at that time they called it light quanta. Now the light is not only a wave, but it is also a particle, from here the wave-particle duality is born. The idea that light was a quantum, seemed complete madness at the time, however, follow Einstein's line of thought and logical conclusion, solve all problems with light in one fell swoop.
The light was a particle, which could explain the ultraviolet catastrophe and the photoelectric effect, but it was also a wave, able to explain shadows and soap bubbles. Then, a few years after Einstein's brilliant and crazy idea, the paradox deepened much more and became rarer. Because what seemed to be a curious mystery of light, was about to become a battle over the nature of reality itself. On the one hand, a new wave of revolutionary scientists led by the brilliant Danish physicist, Niels Bohr and on the other hand, the voice of reason... Albert Einstein, at the top of his prestige and now famous worldwide, without a doubt, a formidable adversary.
The battle began with a deceptively simple experiment and lasted for decades. The strange thing is that the experiment was not even about the light, but rather it was about the particles that make up the electricity, the electron. In the mid-1920s, an experiment was conducted that revealed something totally unexpected about electrons, it should be noted that by that time it was accepted that electrons were tiny blocks of energy, small and solid particles.
In the experiment, they fired a beam of electrons in a crystal and observed how the particles dispersed, that is totally equivalent to shooting an electron beam at a screen with two slits in it, so that the electrons pass through the slots and hit another screen on the back. What the scientists found unusual, is that, when the electron beam hit the screen that was on the back, a series of characteristic lines appeared, something that only give rise to a wave interference pattern, these characteristic lines are bands of light and dark tone, each time this pattern appears is because there is a wave behavior.
First, light, which for a long time was thought to be a wave, turned out to sometimes behave like a particle and now electrons, which for a long time were thought to be small particles, now behave like waves... What a big problem, no? hahaha, it is crazy that light can be wave and particle at the same time or not necessarily have to be at the same time, but can be wave and particle when it pleases, one could say that it is bipolar, it can change its mood "From one moment to another, this makes quantum physics crazy and at the same time very interesting.
The experiment of the double slit using the electron as the protagonist, has another mystery much more unusual than the previous one. This experiment was repeated several times in different laboratories around the world, even firing an electron against two slits, it was observed that each electron that passes individually through the slot is contributing to the wave interference pattern, this leads us to a single conclusion: the electron must be behaving like a wave, therefore, it is passing through the two slots at the same time. But friends, take into account something, a single electron shot and it went through the two slots at the same time and hit the back screen leaving visible the interference pattern. How the hell is this possible? It's crazy.
He who is not shocked by the quantum theory, is because he has not understood.
Niels Bohr.
To explain the strange results of the experiments, Niels Bohr and his colleagues created what we now know as' quantum mechanics, remember that quantum physics is different from quantum mechanics. Quantum mechanics tells us something like this: We can not describe what is traveling as a physical object, the only thing we can describe is the probability of where the electron might be. For a second we forget the electron as a particle and as a wave, let's take these terms out of our mind, now we have to think in the same way as quantum mechanics, think probabilistically, somehow a "wave of probabilities" is the which is going through both slots, producing interference, just as a wave does, then when it reaches the screen, the wave of possibilities almost ghostly becomes real, that is, the electron leaves the probabilistic state and becomes a particle.
To understand how strange this is, let's make a small analogy: If I rotate a coin, it looks blurry and we can not tell if it's heads or tails, at this point we can say it's a combination of the two, but what happens? if I stop it ?, I force the currency to remain in a single state, either heads or tails. Previously it was not known what state I was in because it was the combination of heads and tails, but as soon as I stopped it, the coin made a decision.
Source
This was what Niels Bohr and his colleagues said was happening with the electron, while the coin turns, it can be heads and tails, because a state has not yet been defined, in the same way, the probability wave of the electrons passes through the slots at the same time. Our monera then stops in the face, then the wave of probability reaches the screen, at this moment the electron makes a decision and becomes a particle. Bohr claimed that one can never know where the electron really is until it is observed, and it is not just that the position of the electron is unknown, but strangely it is as if it were everywhere at the same time, remember that we are talking about the probability that the electron is in one place or another.
Keep in mind that electrons are one of the most common and basic building blocks of reality and, however, Bohr is stating that only when we observe it we bring its position to reality, it is as if there is a barrier between us and the world quantum and behind it there is no solid reality, only a potential reality. Things only come true when we knock down the barrier and observe, friends; this point of view was known to him nothing more and nothing less than the Interpretation of Copenhagen. Albert Einstein hated this interpretation like nobody else, and even said a very well-known phrase in the scientific community: Does the moon stop existing when I do not see it?. The German physicist was very much in disagreement, since Bohr put limits on knowledge, even thought that there should be a better theory. For several years, these physics titans were arguing about whether quantum mechanics consisted in renouncing reality or not.
Then, Nathan Rosen and Boris Podolsky joined Albert Einstein to support him in their dispute, they even thought they had found a way to win the Einstein-Bohr debate. These physicists were convinced that they had found a fatal flaw in the Copenhagen Interpretation and their claim that reality changes when it is being observed. At the center of Einstein's argument was an aspect of quantum mechanics called: interlaced. This entanglement is a relationship that has two particles whose destinations are intertwined, when two particles have been created at the same time, many of their properties are linked forever, no matter where they are.
This is where the good part comes from, remember the analogy of the currency that turns ?, well, let's make the same analogy, but this time we will use two coins, when we stop one of the currencies that are spinning and for example: becomes expensive, because the coins are linked through the interlacing, automatically the second coin will become a cross. It is as if the coins were communicating secretly through space and time, no matter how far they are, but the action happened instantaneously, that is, exceeding the speed of light, this was known as the EPR paradox, and was against the theory of relativity. Einstein called this "ghostly action at a distance" and claimed that it was an error of the Copenhagen Interpretation.
Einstein did not imagine quantum particles as a pair of spinning coins, they were more like, for example, a pair of gloves, left and right, separated into boxes. We do not know which box contains which glove, until we make the decision to open one and, just when we know which glove it contains, for example, the left one, we automatically know that the other box contains the right glove.
But, this analogy does not require any "spooky action at a distance", none of the gloves has been altered by the observer, both were left and right from the beginning, the only thing that was altered was our knowledge. So there are questions like: What is the true description of reality?, How do you check if something is real, if something is or is not there without looking ?, How do you look behind the barrier, without altering reality?, well, John Bell arrived at the right time to answer all the questions, devised a great way to solve all the problems that quantum mechanics was causing, Bell's idea was that: Each particle sends secret signals to the other , through space and time, challenging everything we know, we must accept that in the quantum world, reality can not be known. Bell reduced his idea into a single mathematical equation.
This equation had to be verified experimentally, even, each theory and each thought, needs to be verified with real results, a simple idea reduced in a mathematical equation is not enough, you need calculations to verify everything that has been raised. In 1972, the theoretical physicist John Clauser, was the first genuine test of quantum mechanics, it consisted of a crystal that converts laser light into photons that produce two very precise rays, then proceeds to measure a property of the photons, the polarization. A monitor showed the different results obtained and, substituting them in the Bell equation, an unexpected result was obtained for many, the German genius Albert Einstein was the one who was wrong, this gave the victory to Niels Bohr. The two photons with interlaced properties, could not have been chosen from the beginning, but rather, they begin to exist only when we observe or measure them.
Something strange links the photons through space and time, something that we can not explain, let alone imagine, the only means we have are the mathematical equations, the strangest thing is that photons are only real when we observe them. So, we can respond to Einstein: The moon does not exist when we do not observe it. Undoubtedly, this defies common sense, is something illogical and completely strange, but you have to be patient and recognize that this is quantum mechanics, at subatomic levels things do not behave the same as in the macroworld, they are completely different scales governed by laws that do not resemble anything. We only have one thing clear, there are the phantom connections at a distance, the parallel universes, we make reality exist by just looking at it, whatever the truth, the rarity of the quantum world is not going to disappear, it is a complete mystery and it will be for decades, maybe centuries.
Finally I finished this post, it took me a long time to try to get the necessary information and to organize it in the best way, I hope you enjoy it and above all, I hope you understand what it is about. Physics is something that I love and, if we talk about quantum physics, I encourage you to discuss, talk, write and everything that is necessary to spread this beautiful and interesting content.
