Category Archives: Quantum Theory

Q: How can quantum computers break encryption?

Physicist: What follows is the famous Shor algorithm, which can break any RSA encryption key. The problem: RSA, the most common form of public key encryption, is based on the fact that large numbers are hard to factor.  Without going … Continue reading

Posted in -- By the Physicist, Computer Science, Equations, Math, Number Theory, Physics, Probability, Quantum Theory | 19 Comments

Q: How does quantum computing work?

The original question was: Could you give a description of the principles behind quantum computing? And how is it that some problems have a better time-complexity when they’re run on a quantum-computer? Physicist: Particles and sets of particles are frequently … Continue reading

Posted in -- By the Physicist, Computer Science, Engineering, Entropy/Information, Math, Physics, Quantum Theory | 22 Comments

My bad: If atoms are mostly made up of empty space, why do things feel solid?

Physicist: Thanks to a comment in the original post, I did a little research and found that I was wrong, wrong, holy crap wrong.  Here’s some of that comment: “The source of the ultimate “excluded volume” forces is entirely quantum … Continue reading

Posted in -- By the Physicist, Mistake, Quantum Theory | 30 Comments

Q: Can you do the double slit experiment with a cat cannon?

Physicist: It helps to first get an idea of how the double slit experiment is done.  The double slit experiment works for any particle, but in what follows I’ll use light to avoid confusion. Shine light on two slits separated … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory | 23 Comments

Q: If you zoom in far enough, what do particles look like?

The original question was: According to Gertrude Stein “There is no there there.”  But is there “something” there?  I guess we know that atoms are “there,” but what about the constituent parts?  Electrons, protons, quarks, etc.  Are they really “there,” … Continue reading

Posted in -- By the Physicist, Particle Physics, Physics, Quantum Theory | 2 Comments

Q: Which is a better approach to quantum mechanics: Copenhagen or Many Worlds?

Physicist: The Copenhagen interpretation requires that new laws be created that, in addition to being impossible, are completely unnecessary, physically unfeasible, and utterly unjustifiable.  The basic laws of quantum mechanics, when applied at all scales, give you the Many Worlds … Continue reading

Posted in -- By the Physicist, Paranoia, Philosophical, Physics, Quantum Theory, Skepticism | 58 Comments