Beginner’s Guide To Quantum Mechanics
Richard Feynman Once said, “If you think you understand quantum mechanics, you don’t understand quantum mechanics”. Richard Feynman was a brilliant physicist and if he’s saying something like this, what chance do we have of understanding something so bizarre? Well, this statement is a little misleading. Once you have read this article, you will hopefully be more confused and curious about quantum mechanics. In this article, we will cover, what quantum mechanics is, why it is so strange, and some more core principles of quantum mechanics. Let’s start!
Classical Mechanics
Think about the basic things we already know. Apples fall to the ground, If I throw an apple, it could hit someone they could get hurt depending on how hard I throw the apple. Most of the things we do every day can be described by one equation F=MA. All this equation says is that a force on an object is the mass of the object times how fast it’s moving (Force = Mass X Acceleration). The reason quantum mechanics is so weird is that it doesn’t obey this simple and elegant F=MA. Or any other equation in our everyday world. The reason this equation doesn’t work in quantum mechanics is that we are dealing with a very small scale. How small? About 10 billionths of a meter (Smaller than the smallest you can imagine).
Wave-Particle Duality
Let’s get into why quantum mechanics is so confusing. There was once an experiment conducted that in my opinion is what sparked a lot of interest in quantum mechanics. This experiment was conducted by a scientist named Thomas Young. It starts like this: There’s a light beam gun, that shoots photons(particles of light). This beam is placed in front of a sheet with 2 standing rectangular slits. There is a sheet placed behind the first sheet. It looks something like this
When the electrons come on the screen though, they make the patterns we would typically expect. The strange thing happens when no one is observing the experiment. When No one is aware, the particles act like waves! But when we start observing, they start behaving like particles again! So we drew the principle of wave-particle duality. It says that a particle can behave like a wave sometimes and vice versa.
The Wavefunction
The wave function is one of the most important mathematical objects in quantum mechanics. A wavefunction is a mathematical object that can be applied to a particle and returns something called a probability amplitude. The probability amplitude is a wave of probability that gives the probability of the particle being in a particular position. Here’s an example
When a particle is in a waveform it is its wavefunction. The pitchfork-like symbol is the wave function. So in this particular example, the particle wavefunction says that the particle is most likely in between a to b or b to x, etc. The higher the wave, the more likely that particle is in that particular position. If the highest point of the wave is where the particle is, then, why do we have all the other parts of the wave? And if everything is its wavefunction when no one is observing what makes it a particle when we are aware of it? There are many different interpretations of what this could mean, let’s explore the most famous ones.
The Copenhagen Interpretation:- This is the most widely accepted interpretation. What it says, is that when no one is observing the universe, it’s just a wave of different probabilities. Still, when we become aware of it, the waves of probability collapse into one of the probabilities and become the reality we all know.
The Many Worlds Interpretation:- This interpretation is ideal for sci-fi writers. What this interpretation says, is that in every probability the wavefunction has actually happened, in another universe, thus the proof of a multiverse. For example, if a particle’s wave function says that the particle is at x with a 70% probability and at y with a 30%probability, then it’s most likely at x. The other y though is not useless, The other y probability happens in another universe. In this other universe, the particle is at y by 70% and x by 30%. This is just an example, but you get the idea. This interpretation is loved by most people including me because it gives scientific evidence of the existence of other universes! There could be universes where each of us made different choices and became different people! The possibilities are endless!
Conclusion
Hopefully, you now understand why quantum mechanics is not just your average F=MA. If you would like to learn more about this, I would highly recommend PBS Spacetime’s Quantum Mechanics Playlist! Good Luck with your studies!
