Personal Blogs

There is an Only Fools and Horses episode in which the road sweeper Trigger announces that he has won an award for keeping the same broom for 20 years, and adds that the broom has had 17 new heads and 14 new handles.

I was thinking about this and remembered that all the atoms in our bodies get replaced on a surprisingly small time scale. Reading up on it, I found that, according to Time magazine, the turnover is about 98% per year. To put it differently, only about 1 in 50 of the atoms in your body will still be there in a year's time.

In 20 years that would be 1 in 100,000 billion billion billion, which is much more than the estimated number of atoms in a human body. So more or less all the matter that went to make up your body will have been replaced, and you will resemble Trigger's broom in this respect.

I've always been intrigued by this paradox; if all the constituent parts of something are replace, is its identity still the same? It's an important philosophical question, but until now I didn't realise it goes by the name of Theseus's Paradox. 

Plutarch wrote

"The ship wherein Theseus and the youth of Athens returned from Crete [...] was preserved by the Athenians [...], for they took away the old planks as they decayed, putting in new and strong timber in their places."