20 years ago heralded the beginning of a new millennium.  Whilst 20 years does not seem like a lot of time, much has changed since.  Any music played at millenium parties was either in the form of vinyl records or compact discs and any photographs of the occasion would likely be taken on film and only viewable some days later when the prints were ready.  For those fancying a quiet night in and who were not caught up trying to remedy the pending millennium bug, a trip to the local blockbuster to hire out a DVD was possibly the viable option.   All that has changed now, Blockbusters has been replaced by Netflix, CDs and Vinyl by Spotify and Apple Music and the millennium bug by fears of an AI Takeover and a robotic revolt.  What hasn’t changed is that the year 2020 like the year 2000 is going to be a leap year.  February will have 29 days and women long waiting for their prospective spouses to get on one knee and pop the question can do so themselves.  But why do we have leap years in the first place and is it possible that like CD’s and Vinyl, leap years will join the long list of casualties of the digital age?

What are leap years and why do we have them?

What we call a year today is based on a solar year which is the time it takes the earth to rotate around the sun and return to the exact same spot.  This takes around 365 days and knowing this has always been fundamental to the survival of mankind.  By observing movements and patterns of the sun, moon and stars we could calculate relatively accurately when specific seasons would occur and when to plant crops, when to harvest and when nearby rivers would flood.  To that end, calendars were developed and the calendar used by most nations today is based on the Gregorian Calendar which itself was based on the Julian Calendar of 45BC when leap years were introduced.

For simplicity, a solar year is 365 days but in reality, it’s actually 365 days and roughly 6 hours.  This means that every year the calendar year drifts from the solar year by about 6 hours.  In four years this accumulation of 6 hours becomes a full day and thus we add an extra day to the shortest month to correct the drift.  If we ignored this drift we would lose 25 days for every 100 years and seasons would begin to start occurring almost a whole month before they normally would.  It was thus essential to ensure that we were as close to the solar year as possible and thus leap years were introduced.

In 1582 the gregorian calendar was introduced to compensate for a further drift between the solar year and the calendar year.  A solar year is actually about 365 days and just over 5 hours.  This means every leap year actually overcompensates for the error and that’s why we have a leap year every 4 years but not on years ending 00 if that year is not divisible by 400 with no remainder. Following this logic 2000 was a leap year and 2100 will not be a leap year.   Either way for simplicities sake and for most calculations the drift is 6 hours a year.

Why not just add the 6 hours to the end of the year?

When the gregorian calendar was introduced in 1582 the only way to tell time accurately was by using mechanical devices.  Even these had a tendency to drift and had to be corrected regularly.  There was thus no standard way of telling the time universally and adding 6 hours to the end of the year would have created a great deal of confusion.  Most long-distance travel at the time was by sea and mechanical timepieces were used for navigation to calculate one’s position.  Adding 6 hours to the 31st of December would have caused a logistical nightmare.  By simply adding a day after every 4 years these problems were avoided as timepieces would be none the wiser and date accuracy was not as crucial.

Can we do away with leap years in the digital age?

With the dawn of the digital age, most people use digital devices to tell the time.  These are likely connected to a network and can thus be synched to a centralised time.  Any changes in time can be propagated across all devices in the network as occurs with mobile phones.  People living in countries with daylight saving time will also be aware of this phenomenon where digital devices are automatically synched and corrected.  It is thus logically possible to simply add 6 hours to each year.  This would mean possibly making the 31st of December have 32 hours and propagating that across every digital timepiece across the globe.  That means the solar year and the solar calendar will be exactly in sync with the bonus of an extra 6 hours for those out celebrating on new years eve.

Whilst it’s logically possible to do away with leap years the practical reality and the potential cost of implementation far outweigh any perceived benefits.  A solar drift of 6 hours a year is just not that big a deal.  In an era where crops can be grown all year round and shipped across continents and weather conditions can be predicted to the hour, solar year accuracy is not nearly as important for survival.  Most devices also use a time system based on a timestamp.  Leap years have already been programmed into these devices and even though they can be updated some legacy systems will not be upgradable and this could cause a catastrophe similar to that predicted by the millennium bug.  Some digital devices are also based on 2 cycles of 12 hours and will thus not be able to accurately show the 25th hour and onwards.  What will happen to those born on the 29th February from previous leap years?  Current logic is to celebrate their birthdays on either the 1st of March or the 28th of February but now that change will have to be permanent.  Lastly and probably most importantly what will happen to the many romantics across the globe waiting every 4 years to finally pop the question.