2009: A Late Celebration
Created | Updated Dec 17, 2010
Good grief! Eleven and a half months had passed before I suddenly realised that there's something very special about the year 2009. Can you guess what it is?
It's not that it's the last year of the decade. Interesting though that is, we have one of those every ten years.
It's not even that it's the end of the first decade of the Millennium - we have one of those every thousand years.
It's nothing to do with the prime factors of 2009, which, for the record are 7, 7 and 41. In fact, the next year which is a p²q year (as mathematicians might call it) is 2023 (17 * 17 * 7), so it's not too long to wait for that one.
No, 2009 is special because it's an anniversary. It's the anniversary of a year which is yet to come. In exactly 4,000 years it will be 6009.
There, I told you it would be very special.
I Don't Get It
What's that you say? 'What's special about 6009?'
Did I hear you correctly? 'What's special about 6009?' Are you serious? I can't believe I'm hearing this.
OK, I guess I'm going to have to spell it out. 6009 is special because it's invertible. You can turn it upside down and it still reads 6009.
Isn't that amazing? Just bask in the beauty of that symmetry. Write it down, or print it in a large ornate font, then rotate it by 180 degrees - or as mathematicians would say, pi radians - and watch it magically transform itself back into its original image.
Inverse Number Theory
It's invertible, of course, because it is made up of digits whose symbols are themselves invertible when written using our number system. Of the ten symbols we use, three (0, 1 and 8) are directly invertible, whereas two (6 and 9) transform into each other. So to be invertible, numbers need to be made up of these five symbols but not the others (2,3,4,5 and 7). Not only that, but they must be symmetrically matched around the centre of the number (with a 6 being placed opposite a 9 and vice versa). Finally, a date cannot end with a zero, as we don't write leading zeroes in the inverted date.
With all these rules, it's not that surprising that there aren't all that many invertible dates. The last one occurred 48 years ago, in 1961. The last before that was 1881, and before that, 1691. When we entered the Third Millennium, the uninvertible symbol 2 started to appear at the front of our years, and as a result, we will not be seeing any more invertible dates for a while. In fact, the next one is indeed 6009, which as we now know occurs in exactly 4,000 years time.
In the Year 6009...
Considering the mathematical truth which lies in these numbers, it would be fitting if momentous events were to happen within those years. In 1961, Yuri Gagarin became the first man in space. 1881 on the other hand was a turbulent year in American history, with the shootings of President James A Garfield and Billy the Kid, the gunfight at the OK Corrall, and the surrender of Sitting Bull.
But what of 6009? What would be a fitting event for this date in the future? 4,000 years is rather a long time to wait, and it's quite possible that the human race as we know it will no longer be around. Look back in the other direction for 4,000 years and Western civilisation didn't exist; in the UK, we hadn't even built Stonehenge. The seeds were being sown, however, in other parts of the world, notably in China, Egypt and Turkey. Should we survive to 6009, will we have advanced by a similar degree? Or will our relentless thirst for exploiting our Earth's fragile resources have condemned us to a meagre existence on a barren war-scarred planet?
Let's hope that this minus 4000th birthday affords us an opportunity to stop and think for a moment how we might plan our race's survival to the next invertible date.
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