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.

Video contents:

  • 0:00 Intro
  • 0:31 Public Key Cryptography
  • 2:43 Risk posed by Quantum Computers
  • 4:03 Post Quantum Cryptography
  • 5:31 Quantum Key Distribution
  • 10:25 Quantum Cryptography and Summary
  • 11:16 NordVPN Sponsor Message
  • 12:28 Thanks

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.

Sabine Hossenfelder explains the most important and omnipresent ingredients of quantum mechanics: what is the wave-function and how do you calculate with it.

Much of what makes quantum mechanics difficult is really not the mathematics. In fact, quantum mechanics is one of the easier theories of physics. The mathematics is mostly just linear algebra: vectors, matrices, linear transformations, and so on. You’ve learned most of it in school already! However, the math of quantum mechanics looks funny because physicists use a weird notation, called the bra-ket notation. I tell you how this works, what it’s good for, and how to calculate with it.