Category Archives: Physics

Q: How far away is the edge of the universe?

Physicist: If you ever hear a physicist talking about “the edge of the universe”, what they probably mean is “the edge of the visible universe”.  The oldest light (from the most distant sources) is around 15 billion years old.  Through … Continue reading

Posted in -- By the Physicist, Astronomy, Physics, Relativity | 79 Comments

Q: Why do superconductors have to be cold?

Physicist: The long answer is really, really long.  Superconductivity comes in a variety of different forms, and there’s a different explanation for each.  To sum them up in a thumbnail sketch of a thumbnail sketch: In conductors, the primary cause … Continue reading

Posted in -- By the Physicist, Physics, Quantum Theory | 5 Comments

Q: How/Why are Quantum Mechanics and Relativity incompatible?

Physicist: Quantum Mechanics (QM) and relativity are both 100% accurate, so far as we have been able to measure (and our measurements are really, really good).  The incompatibility shows up when both QM effects and relativistic effects are large enough … Continue reading

Posted in -- By the Physicist, Entropy/Information, Physics, Quantum Theory, Relativity | 33 Comments

Q: What’s that third hole in electrical outlets for?

Physicist: Ground. The zero volt, large-slit wire is called the “return” or “neutral” line.  If it seems strange that the power company would supply you with a wire that has no voltage, keep in mind that what you really need … Continue reading

Posted in -- By the Physicist, Engineering | 9 Comments

Q: Do physicists really believe in true randomness?

Physicist: With very few exceptions, yes.  What we normally call “random” is not truly random, but only appears so.  The randomness is a reflection of our ignorance about the thing being observed, rather than something inherent to it. For example: … Continue reading

Posted in -- By the Physicist, Philosophical, Physics, Quantum Theory | 177 Comments

Q: Could a simple cup of coffee be heated by a hand held device designed to not only mix but heat the water through friction, and is that more efficient than heating on a stove and then mixing?

Physicist: You could definitely make a device that heats water through mixing.  In fact, that’s exactly how scientists (Joule) figured out how to equate heat energy and kinetic energy in the first place. When you introduce turbulence to a system … Continue reading

Posted in -- By the Physicist, Engineering, Physics | 2 Comments