Physics - BN

Videos on the topic

Quantum physics

Double slit experiment

You know what, why not? An electron is particle-wave duality, meaning it acts like both a particle and a wave. Before you measure it, it is a wavefunction (a mathematical concept). You get a probability distribution by getting the absolute square of the wavefunction. You can see where the electron is more likely to be, and less likely to be.

You can also see this in the double slit experiment. Firing an electron at the double slits, it is a wave, going through both slits at the same time, before splitting into two more waves which overlap. Where they add together, you get a high probability distribution and where they cancel out you get a low one. This means that the electron has some more likely places to be "concentrated" so you get a rough bar shape, which is an interference pattern.

Oh, and also, there's the Heisenberg's uncertainty principle, which states that if you know one thing, you have no idea of the other. Let's say I have a sine wave wavefunction (f1) (wave with one wavelength). Well, I definitely know the momentum of the electron, there's litteraly one wavelength. Trouble is, where IS the electron. Because there is an even probability distribution, the electron could be anywhere. What if I have a wave that just has one giant vertical line (f2). Well, I know the electron is at the tip of the line, but I have no idea what momentum it has.

This is useful for any wave, the high poins are crests, low points are troughs, the height is the amplitude, the wavelength is the literal length of one wave, and the frequency is how many times the wave passes a fixed point in 1s, measured in Hertz.

f1

f2

Oh and also, electrons are in a superposition (2 places at once), so it would look something like this and can be made by adding (superimposing) two other waves.

Superposition

Quantum tunneling is when a wavefunction can pass through a barrier if it is thin enough, because the wavefunction's amplitude decreases exponentially while moving through the barrier. This happens in the sun, where Hydrogen usually repel but sometimes quantum tunnel into each other, creating helium and causing nuclear fusion.

When two wavefunctions quantum tunnel into each other they get entanglement, which means that no matter how far away they are, if you measure one, the electron will always be there on the other. This is faster than light!!!!!!😲 And then Einstein got worried because he said that you can't transmit information faster than light, BUT, it's not actually transmitting info, so he's not disproved.

Lesson 1 - What is Physics?

Physics is the study of how matter and energy, and their interactions.

It can be seen all around you - from cars to flashlights

Lesson 2 - Energy

Energy causes physical objects to do work or cause change. There are many types of energy:

Potential energy - This is energy that is stored, so it exists but is not currently doing anything. Think of a car on top of a slope, or a charged battery.
Kinetic energy - This is the energy of movement. Everything that moves has this type of energy
Chemical energy - This energy is stored in chemical bonds
Thermal energy - Heat.