"theoretically could you build a large enough lens to concentrate moonlight to start a peice of paper on fire. My 16 year old son and I are locked in this debate and we need an expert opinion."
-Glen Hawkins (age 44)
Potential To Do Work By A Displaced Object
Less Than One Photon?
Black Hole Gravity And Magnetism
Batteries For Led Lights
Weight Of Photon
Neutrinos Faster Than Light?
Axioms And Theorems
Ozonated Distilled Water
Quantum Paths And Such
7684 questions have been answered online since 1998 by volunteers from the Department of Physics at the University of Illinois' Physics Van outreach program. We've tried hard to make this the most reliable physics Q&A site on the Web, but no site is perfect, as we explain on this note. Our Baloney feature provides examples of how shaky many other sites are.
If you'd like to ask us a new question, not already covered, please read our answering guidelines first. We try to answer as many questions as we can, but it's not always possible to answer them all. Questions from kids are especially welcome.
Although we recommend not using our informal site as a cited reference, students who are in a rush and can't find a more proper peer-reviewed source can check our citation information section.