Recent content by dwahler

The simple answer is that photons don't interact with each other. They can, however, interact with electrons, such as the ones in photosensitive molecules in camera film or your eye.

I assume this is the video in question: http://www.willitblend.com/videos.aspx?type=unsafe&video=magnets First of all, even two neodymium magnets of that size would be nearly impossible to separate by hand. Plus, all the rare-earth magnets I've seen are chrome-plated on the outside and have a...

It sounds like you're using Euler integration, which is simple but tends to accumulate errors pretty quickly. You can improve the precision a lot by switching to another method with better error bounds, like Runge-Kutta.

You can use a disassembler to help you decode the machine-level instructions, but that's about it. AFAIK, there is currently no way to reliably and automatically reverse-engineer machine code to a high-level language; it's a much more complex problem than you might think.

I was referring to this: # Use this module to solve Sudoku puzzles with code like this: # # require 'sudoku' # puts Sudoku.solve(Sudoku::Puzzle.new(ARGF.readlines)) Put that in a new file called "sudoku_solver.rb" or something and run it. You'll need to supply the input filename on...

Although you didn't make this clear, that code is from Example 1-1 of "The Ruby Programming Language" by David Flanagan and Yukihiro Matsumoto. Did you try reading the very first comment in the example?

foo :: a -> Int -> Int foo x = \x -> x+1 This can be written more concisely as: foo = const (+1)

Check again. Based on your equations so far, I get: h_1 = 3.46 \cdot 10^8 \ \mathrm{m} d = 3.84 \cdot 10^8 \ \mathrm{m} h_2 = 4.31 \cdot 10^8 \ \mathrm{m}

Try calculating the actual distances for both roots. Would you encounter both of them on a trip between the Earth and the moon?

Not sure if you want the entire answer, but here's a hint: over the course of a year, the direction of the Earth's orbital motion around the sun rotates through a full 360 degrees. How does this change the component of the velocity towards or away from the star being observed? What effect would...

This may be a long shot, but is it possible that you got one of those little sticky magnetic tags stuck to something you're carrying, like a backpack or your shoes? How long ago did you first start setting off the alarms?

I've noticed this effect myself with certain brands of instant hot chocolate. My theory is that the stirring process changes the distribution of suspended particles in the liquid, and that as they settle the speed of sound in different areas changes. The reason I suggest this is that the pitch...