Sabine Hossenfelder explains what differential equations are, go through two simple examples, explain the relevance of initial conditions and how differential equations generally work, and then discuss what this means to the question whether the future is determined already.

Time Index:

0:00 Motivation and Content Summary

0:55 Example Disease Spread

3:25 Example Newton’s Law

5:18 Initial Values

6:15 What are Differential Equations used for?

7:08 How Differential Equations determine the Future

In this video, Sabine Hossenfelder explains how public key cryptography works on the internet today, using RSA as example, what the risk is that quantum computers pose for internet security, what post-quantum cryptography is, how quantum key distribution works, and what quantum cryptography is.

Geek’s Lesson provides this full nine hour source on quantum mechanics.

Quantum mechanics (QM; also known as #quantum #physics, quantum theory, the wave mechanical model, or #matrixmechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest scales of energy levels of atoms and subatomic particles.

Table of Contents

(0:00) Lesson 1: Fundamentals

(10:03) Lesson 2: Complex Numbers in Quantum Mechanics

(27:20) Lesson 3: Representing Complex Things

(43:03) Lesson4: Superposition and Stationary States

(1:0:00) Lesson5: Infinite Square Well

(1:19:48) Lesson 6: More ISW + Dirac Notation

(1:39:07) Lesson 9: QSHO, Operator Method, part 1

(1:55:37) Lesson 10: QSHO Part 2

(2:18:42) Lesson11 SHO Analytical

(2:32:56) Lesson13 Free Particle (redo)

(3:00:28) Lesson14 More Fourier Transforms, inner products

(3:22:10) Lesson15 Delta Bound States

(3:32:50) Lesson16: Scattering States of the Dirac Delta Potential + More DFT concepts

(4:06:17) Finite Square Well (updated)

(4:32:43) Tunneling and Bonding

(5:08:05) Review (or intro) to Linear Algebra + Notation

(6:03:52) Formalism I

(6:14:20) Formalism II More Quantum Formalism

(6:43:49) Formalism III: Time Evolution + More Change of Basis

(7:39:45) Exam 3 Prep, More time evolution of Ammonia molecule

This video is about Bell’s Theorem, one of the most fascinating results in 20th century physics.

Even though Albert Einstein (together with collaborators in the EPR Paradox paper) wanted to show that quantum mechanics must be incomplete because it was nonlocal (he didn’t like “spooky action at a distance”), John Bell managed to prove that any local real hidden variable theory would have to satisfy certain simple statistical properties that quantum mechanical experiments (and the theory that describes them) violate.

Since then, GHZ and others have managed to extend the theoretical work, and Alain Aspect performed the first Bell test experiment in the late 1980s.

Sabine Hossenfelder explains one of the most common misunderstandings about quantum mechanics — that quantum mechanics is about making things discrete or quantifiable.

This must be one of the most common misunderstandings about quantum mechanics, But is an understandable misunderstanding because the word “quantum” suggests that quantum mechanics is about small amounts of something. Indeed, if you ask Google for the meaning of quantum, it offers the definition “a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents.” Problem is that just because energy is proportional to frequency does not mean it is discrete. In fact, in general it is not.