Category Archives: Quantum Theory

Q: Why is Schrodinger’s cat both dead and alive? Is this not a paradox?

One of the original questions was: A basic rule of logic is that something cannot contradict itself. It is impossible for P to be true and not true. Doesn’t Schrödinger’s cat violate this law and therefore invalidate logic? Physicist: The … Continue reading

Posted in -- By the Physicist, Logic, Physics, Quantum Theory | 48 Comments

Q: Does quantum mechanics really say that there’s some probability that objects will suddenly start moving or that things can suddenly “shift” to the other side of the universe?

Physicist: In a word; nope. The Heisenberg Uncertainty Principle is a statement about how “certain” some combinations of quantities can be.  The most commonly referenced is the “position and velocity” version of the Uncertainty Principle, that says that the more … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory, Relativity | 29 Comments

Q: What is quantum teleportation? Why can’t we use it to communicate faster than light?

Physicist: Contrary to its exciting name, quantum teleportation doesn’t involve any physical stuff suddenly disappearing and then reappearing somewhere else.  Instead it’s a cute, clever, technique for transferring an unknown quantum state of one system (usually a single particle) to … Continue reading

Posted in -- By the Physicist, Entropy/Information, Physics, Quantum Theory | 28 Comments

Q: Since all particles display wave-like characteristics, does that imply that one could use destructive wave interference to destroy or at least drastically change a particle?

Physicist: The wave-like property of particles allows you to do a lot of cute things with particles that would otherwise seem impossible, but making a particle disappear isn’t one of them.  You can use destructive interference to make it very … Continue reading

Posted in -- By the Physicist, Particle Physics, Physics, Quantum Theory | 4 Comments

Q: Two entangled particles approach a black hole, one falls in and the other escapes. Do they remain entangled? What about after the black hole evaporates?

Physicist: If all you had access to was the remaining particle, you’d never know the difference. The way entanglement is often described in popular media makes it sound like voodoo; there’s some kind of magical connection between two or more … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory | 19 Comments

Q: What is the probability of an outcome after it’s already happened?

Physicist: There are a lot of subtleties to this.  Reading the question, your gut reaction should be “Duh, it’s 100%!  Wait, is this really a question?”. And yet, there are many times in which you may find yourself estimating probabilities … Continue reading

Posted in -- By the Physicist, Philosophical, Probability, Quantum Theory | 11 Comments