Online Cortex Thoughts on Science and Technology

One of the groups I belong to on LinkedIn posted an interesting problem that was published in a New Scientist article on the Gathering for Gardner meeting. The problem goes like this:

I have two children.
One is a boy born on a Tuesday.
What is the probability I have two boys?

Can the fact that you were told that one of the boys was born on a Tuesday tell you anything about whether both children are boys?
Indeed it can!

Find out more HERE:
http://kevinknuth.com/blog/2010/06/bayes-theorem-and-our-poor-sense-for-probability/

Posted under Probability

I came across a lovely video of an experiment where CO2 is used to put out flames.

I myself once performed a demonstration in my physics class where I compared a Helium filled balloon to a Carbon Dioxide filled balloon. Of course, one floats and the other falls to the ground (faster than a balloon filled with room air).

I then showed how my voice sounds higher when I inhale Helium due to the fact that the speed of sound is faster in Helium than in air, and the waves pile up as the slow down at the Helium-Air interface.

To be clever, I asked my students what happens when you breathe in Carbon Dioxide and try the same trick. Your voice should sound far lower. What I didn’t count on was that when you breathe pure Carbon Dioxide, it combines with the water in your lung membranes and forms Carbonic Acid. I almost coughed to death during the demo.

Next time Michelle Bachmann says that CO2 is harmless, have her take a breath out of a CO2 balloon!

Kevin Knuth
Albany NY

Posted under Fun, Physics, Stuff