### What is a pirate's favorite bathtub physics demonstration?

Arrrrrrrrrchimedes Principle!
Everyday is "Talk Like a Physicist Day" here at the American Center for Physics. However, we do make a few exceptions: April 1st is "Talk Like a Chemist Day", Feb 30th is "Talk Like a String Theorist Day" (which is yet to be observed), and our favorite is Sept. 19th "Talk Like a Pirate Day". Avast! Today we leave our diffarrrential oparrrators and arrrgon tubes to the lubbers and shout like a pirate.
Many years have passed since the days physicists brushed sails with pirates. Talk Like a Pirate Day allows us to remember the adventurous times when discovering our universe took us out to dangerous waters swimming with pongos and rogue waves. In 1699 Edmund Halley embarked on such an adventure to measure the mysteriously elusive magnetic north and south poles. He discovered a method for determining a ship's position while at sea. While we use GPS today to find our way, Halley had only the stars and a compass. One slight miscalculation would crash his ship into shallow rocks or even worse: pirate waters. In addition to fending off pirates, he also calculated the orbits of the planets and comets, one of which bears his name. He also derived the famous gravitaional property called the Inverse Square Law. It says that the force of gravity is proportional to one over arrrrrrrrrgh squared. Consequently, pirates were quite fond of Halley's work and hence he was able to make many discoveries without too much trouble. However had he set sail on September 19th, he might have mistaken his crew for mutinous pirates.
Upon, Halley's return, he convinced Isaac Newton to publish his famous work on the laws of motion and calculus. Halley also personally funded the book's publication since the Royal Society had already spent their book budget on the not so memorable history of fish.
Let's thank Halley the next time you take a darrrrrivative!

1. Excellent! Really tickled me. Why are pirates called pirates? Because they aaaaarrrrggghhhh!

### How 4,000 Physicists Gave a Vegas Casino its Worst Week Ever

What happens when several thousand distinguished physicists, researchers, and students descend on the nation’s gambling capital for a conference? The answer is "a bad week for the casino"—but you'd never guess why.

### Ask a Physicist: Phone Flash Sharpie Shock!

Lexie and Xavier, from Orlando, FL want to know:
"What's going on in this video? Our science teacher claims that the pain comes from a small electrical shock, but we believe that this is due to the absorption of light. Please help us resolve this dispute!"

### The Science of Ice Cream: Part One

Even though it's been a warm couple of months already, it's officially summer. A delicious, science-filled way to beat the heat? Making homemade ice cream.

(We've since updated this article to include the science behind vegan ice cream. To learn more about ice cream science, check out The Science of Ice Cream, Redux)

Over at Physics@Home there's an easy recipe for homemade ice cream. But what kind of milk should you use to make ice cream? And do you really need to chill the ice cream base before making it? Why do ice cream recipes always call for salt on ice?