“Happy Symmetry Day” a colleague said to me as I walked into his office on Wednesday. It took me a while to work out that he was referring to the fact that in the American calendar, November 2nd, 2011 is written symmetrically – 11022011.
This precise type of mirror image is called a Palindrome, defined as a symmetric word, phrase, number or other sequence of units that reads the same forward and backward. It originates from the combination of two Greek words palin (meaning backward) and dromos (meaning running). Maybe I was confused, as under the British way of writing dates, we had already had ours way back on February 11th!
This year is special because it contains two palindrome calendar dates: Jan. 10, expressed as 1102011 and Nov. 2nd. In the British system the dates are February 11th and 1st October.
After 2011, there will only be one more year this century containing two palindrome dates; and that will happen in 2021.
Palindrome dates are extremely rare. Before the beginning of this century, the last palindrome date of the second millennium occurred approximately 621 years ago on August 31, 1380 A total of 43 palindrome dates occurred during the second millennium; however, they all happened between the 11th and 14th centuries. No palindrome dates existed between the 15th and 20th centuries.
Commonly used palindrome words include dad, mum, wow and radar; common names are Bob, Eve, Anna, and Hannah; and some common palindrome phrases are "A Toyota," "Never odd or even" and "No lemons, no melon”.
But does it really matter? Who was it, after all, who famously said “The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us.”?