You may have seen something like this come across your email recently :
8:02 pm on February 20 this year (2002) will be an historic moment in time. It will not be marked by the chiming of any clocks or the ringing of bells, but at that precise time, on that specific date, something will happen which has not occurred for 1,001 years and will never happen again. As the clock ticks over from 8.01pm on Wednesday, February 20, time will, for sixty seconds only, read in perfect symmetry 2002, 2002, 2002, or to be more precise - 20:02, 20/02, 2002. It is an event which has only ever happened once before, and is something which will never be repeated. The last occasion that time read in such a symmetrical pattern was long before the days of the digital watch and the 24-hour clock at 10:01 am on January 10, 1001. And because the clock only goes up to 23.59, it is something that will never happen again.
Amusing … but it is a crock! (The "last time" date is wrong, and it will happen again!)
First of all, let us grant them the arrangement of hh:mm, DD/MM YYYY, which is not exactly a universal date time format….
Under this definition of "symmetric" (i.e., forward/backwards, as well as three repeating sets of 4), there were at least two other "symmetric" dates previously on 01:10 01/10 0110 (Oct 1st, 110 at 1:10 AM) and on 11:11 11/11 1111 (Nov 11th 1111 at 11:11AM) and there will be another "symmetric" date here : 21:12 21/12 2112 (Dec 21st 2112 at 9:12PM) …. So much for the "last time" it happened, and so much for "never again"!.
Now, if you are still reading .. I'll get nit-picky ... If you are just looking for simple forward/backward symmetry (admittedly, not what the original email implied), it is all over the place. There seems to be a sequence of day/months that gives inner symmetry, then we just match the year and time - for example, here is a sequence in 1011:
| 11:01 01/10 1011 (Oct 1st) | 11:01 10/01 1011 (Jan 10th) | 11:01 11/11 1011 (Nov 11th) |
| 11:01 20/02 1011 (Feb 20th) | 11:01 21/12 1011 (Dec 21st) | 11:01 30/03 1011 (Mar 30th) |
Using these combinations of day/months that are symmetric - just find a time/year combo that is symmetric - piece of cake! This sequence happens for many years (such as 12:21 21/12 1221, 12:41 21/12 1421, to name only two) … skipping a whole bunch of them, we come to the most recent of the forward/backward symmetry - how about last month : 20:02 10/01 2002 (Jan 10th, 2002 at 8:02 pm) (note, that is one of our "sequences"!)
When is the next forward/backward symmetric date: How about next month : 20:02 30/03 2002 (Mar 30th)
Those sequences appear all over the place : 21:02 20/02 2012, 22:02 20/02 2022, 23:02 20/02 2032, … 23:09 20/02 9032 ...
Which brings us to the last (in our 4 digit year world) time that simple forward/backward symmetry will happen : 23:59 21/12 9532 (Dec 21st 9532)
So, my charge to you … go forth and spread the correct information!
Mea Culpa! Thanks to those that pointed out corrections to my correction page! Doh! I think I fixed them all.
The few, the bored, the 133 people that have seen this page.