Monthly Archives: February 2011

Q: What are the equations of electromagnetism? What all do they describe to us?

Physicist: Electromagnetism and all the involved math are surprisingly visual sciences.  Understanding Maxwell’s equations (the equations of electromagnetism) involves pictures aplenty. In these equations and are physical constants that dictate how strong the electric and magnetic forces are, but when … Continue reading

Posted in -- By the Physicist, Equations, Physics | 13 Comments

Q: What is the entropy of nothing?

Mathematician: In physics, entropy relates to the number of states that a system can be in. If a system actually contained absolutely nothing, then (quantum mechanical considerations aside), it would only have one state, and therefore would have 0 entropy … Continue reading

Posted in -- By the Mathematician, Entropy/Information, Philosophical | 6 Comments

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 | 18 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 | 21 Comments

Q: What causes buoyancy?

The original question was: I know that the buoyant force on an object equals the weight of the liquid that it displaces.  However, I have some questions as to what it means to ‘displace’ a liquid,  for example, does an … Continue reading

Posted in -- By the Physicist, Physics | 3 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