### June 14 - International Bath Day

Posted on June 14, 2018

I bet you think today is all about relaxing in a nice bubble bath.

Or maybe soaking in a tub full of warm water and just a bit of delicious smelling almond essential oil.

I know that's what I thought "International Bath Day" would be all about.

But, no, I was wrong (and I bet you were, too); today is about a particular bath taken a loooooooong time ago by a particular Ancient Greek mathematician and inventor.

Today is about Archimedes (who was born in Sicily around 287 BCE and lived until around 212 BCE).

The day is about a really smart guy trying to figure out a very tricky problem...and being struck with inspiration in his bath!

We know very little about Archimedes, even though he is regarded as one of the most important Ancient Greek scientists (and engineers / astronomers / inventors) and probably THE greatest Ancient Greek mathematician (and one of the greatest mathematicians of all time). We are not sure exactly what day he was born or died, and we certainly do not know exactly what day the famous bath occurred - or even IF the bath-inspired inspiration happened the way the story goes...

But this is how the story goes:

Once upon a time there was a king who had a crown made by a goldsmith. It was supposed to be pure gold, but the king suspected that the goldsmith had mixed in some silver as a dishonest way of making more money on the order.

Gold is more dense than silver, so there should be a way of figuring out if the crown was pure gold or gold-and-silver. All you had to do was weigh the crown and then divide the weight by the volume of the crown (the amount of space the crown takes up), and the result is the density of the crown. You can then compare the density to the known density of gold. If the crown is less dense, then for sure the goldsmith was dishonest and subbed in some silver.

But...that leaves a really difficult problem. How do you measure the volume of the crown?

If you could melt it down into a solid cube of metal, no problem! You measure the length and width and height (and if it is actually a true cube, the three measures are the same), and you multiply the three numbers. The result is the volume.

But...but...

You CAN'T melt down the crown!!!! What if the goldsmith wasn't dishonest? You've just lost all the beautiful craftsmanship used to make this ornate headpiece!

The story goes that the king turned to the brilliant Archimedes to figure out the volume of the crown without damaging it.

Supposedly, Archimedes tried to think of a way to solve the problem for a while and then decided to take a break, take a bath, and get back to the problem after that relaxing rest. When he stepped into the almost-full bath...

...Water slopped over the sides of the tub, onto the ground, and the mathematician was suddenly struck with a lightbulb moment (even though lightbulbs hadn't been invented yet!). He had the answer: you immerse the crown in water, and you measure the displacement of the water, and voila! You have the volume!

This idea prompted Archimedes to run through the town naked (remember, he was stepping into his bath when he thought it up) shouting "Eureka!" Which means "I have found it!"

And, the story goes, the crown was tested with this water-displacement experiment, and it was proved that the goldsmith had indeed mixed in silver.

The bath story gave rise to the phrase "Eureka moment" and (with the connection of gold and "Eureka!") may have inspired California's motto of "Eureka," which is based on the importance of the discovery of gold and the subsequent Gold Rush in California becoming a state.

For an alternate story about Archimedes's most famous principle, check out this short, animated video

Our take-away from International Bath Day could be that, when we cannot seem to solve a problem, we could take a break and either walk briskly, enjoy a bit of nature outdoors, take a bath, or even catch a cat-nap. When we take breaks, we tend to come back to the problem refreshed and ready to be more creative in finding a solution. Not just that, the frontal lobe brain networks work best when your brain is quiet rather than when you are putting out effort to finding a solution.

So you might have an Aha! or Eureka! moment right in the middle of your walk / bath / whatever.

"They" (by which I mean people-in-general or so-called experts) are always telling us to take breaks, exercise, refresh ourselves out in nature, and so on. In this case, "they" are absolutely correct!

### Also on this date:

Birthday of John Bartlett of “Bartlett's Familiar Quotations”

### Day of Mourning in the Baltic Nations

(Third Thursday of June)