Radiation has a very bad reputation. There is something about it that scares the daylights out of people. This is understandable since the devastation of Hiroshima and Nagasaki produced graphic images of the devastation that radiation could cause. The Cold War generated additional fears of radiation silently killing off large numbers of people. Even today, one sees the fears generated by the phrase ‘dirty bombs’ that kill by nuclear radiation. [Read more…]

I am one of those people who can fall asleep almost anywhere at almost any time, even on planes. But in addition to such naps, I also value getting a good continuous night’s rest, which is usually conceived of as about eight hours of uninterrupted sleep.

So I was surprised by this report of a study that said [Read more…]

The two posts on changing the seasons (here and here) resulted in a lot of interesting information in the comments and it seems like there is quite a geographical variation in how the seasons are demarcated, with the US possibly being an outlier in using the solstices.

Reader ahcuah is a kindred soul and has kindly sent me the data he collected over a full year of the daytime high and low temperatures. He lives fairly close to Cleveland and [Read more…]

If an object like a thrown ball or a car is heading towards us, we know that we can react and take effective avoidance strategies very quickly. How do the neurons in our brains manage to work so fast to determine the trajectory and decide what is the best avoidance strategy? It is clearly automatic and not done by our conscious brains.

A recent study, the conclusions of which are summarized [Read more…]

I think that most people are familiar with Sudoku puzzles. There are some interesting questions that can be asked such as what is the minimum number of the 81 boxes in the grid that need to be filled in initially (the ‘clues’) in order to be able to obtain a unique solution?

It is known that for at least some puzzles one can obtain a unique solution with 17 clues, and no one had found any puzzles with 16 clues that had unique solutions. But is 17 the minimum number required? If you [Read more…]

I got the lightning puzzle that I posed yesterday from the latest book by Steven Pinker The Better Angels of Our Nature: Why Violence Has Declined that I reviewed in December. He uses it to illustrate that our intuitive notions of randomness and probability can easily lead us astray.

Here is the problem again.

Suppose you live in a place that has a constant chance of being struck by lightning at any time throughout the year. Suppose that the strikes are random: every day the chance of a strike is the same, and the rate works out to one strike a month. Your house is hit by lightning today, Monday. What is the most likely day for the next bolt to strike your house?

Here is his answer followed by [Read more…]