There is a famous anecdote that over 2,000 years ago the ancient Greek philosopher, mathematician, physicist and engineer Archimedes of Syracuse (c. 287-212 BC) was relaxing in his bath and contemplating the mysteries of nature, when he suddenly realised why some objects float in water. The story goes that he jumped out of his bath and ran down the street yelling “Eureka! Eureka!” to celebrate his discovery, which in Greek means “I have found it!”
Archimedes was responsible for all sorts of mathematical and engineering developments such as the screw pump, as well as various military inventions including a heat ray device consisting of lenses and mirrors intended to focus the power of the sun in order to set fire to enemy ships! Although the tale of his revelation in the bath may be apocryphal, he is now best known for his eponymous principle which states:
“If a body is wholly or partially immersed in a liquid, then the upward force of buoyancy exerted by the liquid on the body is equal to the weight of liquid displaced.”
This explains why when you get in a bath, swimming pool or hot tub a lot of the feeling of weight goes away and you feel as if you are free from gravity due to the effects of buoyancy. This is very good news for the body as it relieves a lot of pressure on joints and muscles. This can be especially beneficial for joints which are usually weight-bearing, allowing the spine to decompress and soothing painful knee and hip joints. Indeed, immersion in water can be used to treat a variety of muscular-skeletal conditions and injuries.
The feeling of buoyancy, combined with the warmth of the water and the massaging effects of the jets, make relaxing in a hot tub the ideal way to soothe the body and clear the mind after a hard day at work, or indeed any other time. One wonders what Archimedes would have made of the luxury of a modern hot tub, and whether he’d have been quite so quick to leap out and run down the street shouting eureka if he’d had access to one.