By Aziz Inan
We encounter symmetry on a regular basis in our daily lives in many different ways, in both the natural and human-made world. Symmetry also possesses the magic power of drawing our attention. Most of us value and enjoy experiencing symmetry both visually and mentally because it conveys a sense of the aesthetic, of balance, beauty, equality, evenness, harmony, neatness, perfection, pleasure and/or simplicity. Often times, we also incorporate symmetry in what we do in the arts and/or sciences to evoke at least one or more of these attributes.
A palindrome is 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 (means backward, again) and dromos (means running). The Greek word palindromos means "running back again." The word "palindrome" was first coined and introduced in the literature by English writer Ben Jonson in 1623, on line number 34 of his poem titled "An Execration upon Vulcan," which is poem number 43 in a collection of Jonson's 89 poems first published in 1640 under the title Underwood.
Commonly used palindrome words include dad, mom, eye, pup, wow, deed, noon, civic, kayak, level, madam, radar, refer, rotor, solos, rotator and racecar. There are also palindrome names such as Bob, Eve, Anna, and Hannah. Some examples of palindrome phrases that are constructed for amusement are "A man, a plan, a canal-Panama," "A Toyota," "Madam, in Eden I'm Adam!" "Never odd or even," "No, it can assess an action," "No, it is opposition," "No lemons, no melon," "Rats live on no evil star," "Rise to vote, Sir," and "Step on no pets!"
We also enjoy palindrome numbers in our lives such as palindrome years, ages, room numbers, phone numbers, street numbers, zip codes, etc. For example, my birthday will be special next year because I will turn 55. My old office number 303 is greater than my new office number by 88. In 2002 the University of Portland celebrated the 101st anniversary of its founding. 2112 will mark Mother Teresa's 202nd birthday. Palindrome numbers are fun to encounter and they indeed stand out.
Assuming each calendar date in all four-digit years is assigned a single eight-digit full date number as MMDDYYYY (where the first-two digits MM is the month, DD is the date, and YYYY is the year number), some of these dates are palindrome numbers and these dates are referred to as palindrome dates. For example, the first palindrome date of the 21st century occurred on Oct. 2, 2001 since the full date number of that day is 10022001.
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 (since that date is 08311380). 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.
The second palindrome date of this century will occur on Jan. 2, 2010 (since that date is 01022010) and this will be the second palindrome date in our lives. After this one, the third will occur next year, on Nov. 2, 2011 (11022011) and the fourth will be on February 2, 2020 (02022020). There are a total of 12 palindrome dates in the 21st century, with the last one occurring on Sept. 2, 2090 (09022090). Note also that all the palindrome dates of this century will fall on the second day of the month. After this century, 12 more palindrome dates exist in the 22nd century (all being on the 12th day of the month) and another 12 in the 23rd century (all on the 22nd day of the month). The last (36th) palindrome date of this (third) millennium is to occur on Sept. 22, 2290 (09222290). After that, no more palindrome dates will happen for another 711 years until the next one in 3001, on Oct. 3rd (10033001).
Palindrome dates are indeed fascinating and there is one coming up pretty soon on the second day of next year. I suggest we not only enjoy that day in itself but also encourage ourselves and others around us to look for other palindromes that exist in our surroundings.
Aziz Inan is a professor of electrical engineering at the University of Portland