====== 2009.10.22 - inheritance of history ======

recently my complaining nature took over again. i started thinking about what are some things on this world for? there are many things that as they are, though they do not seem to have ANY logical explanation except just one: we got used to them.


===== 24h, AM/PM and more =====
as everyone knows full rotation of earth around takes 24h. what is the idea behind 2x12h mode (AM/PM), common in England and USA and few others?

if you live in 24h-time country don't get too excited yet -- do you have wall clock somewhere around? take a closer look at it. what do you see? yes -- it has just 12h drawn on it! as far as i remember i had a chance to see 24h wall clock one or twice in my whole life! why? because we're used to it.


===== time vs. zones =====

you all know [[wp>UTC]] time. but what is time in your country? it's [[wp>GMT]] plus or minus few hours. but that would be too simple, so let us add more to our model: there is daylight saving, thanks to which depending on the time of year most countries change time adding or subtracting one hour! why? it was used to switch working hours, so that more of it will be when sun shines saving some energy on artificial light. does it work? not exactly -- now days it is quite commonly thought to be more of a problem than an advantage of any sort.

but wait! there is even MORE! there are countries that have time shifted from [[wp>GMT]] more than full yours! example can be [[wp>Afganistan]] having 4.5h time difference.

but wait! did you know, that [[wp>GMT]] is shifted to [[wp>UTC]] in some parts of the year? did you know that [[wp>UTC]] have leap seconds?

what is that whole mess for? it is pure-historical! wouldn't it be simpler just to have one time zone on the whole planet ([[wp>UTC]] seems a good candidate -- no daylight saving mess), using 24h clock with 24-hours painted on it? what is the problem of going out to work/school between 0200h and 1000h, if this would be the time when sun shines in a given region? this is only our habit to get up around 0600-0800h every day -- nothing more.


===== the length of the second =====
not many people know what is exact definition of a [[wp>second]]. in fact it is duration of 9192631770 periods of radiation of caesium 133 atom((this definition is not exact, but it gives the main idea. for more read [[wp>second|definition on wikipedia]])). why that? well -- it has been normalized some time ago to ensure proper understanding of this time unit keeping in tact with previously, more coarse definitions.

what does it mean? not much. there is one interesting thing though -- do you know the speed of light? it is c=299792458[m/s]. it is very basic constant in modern physics. few years ago i've read [[wp>John Gribbin|John Gribbin's]] book "Quantum Physics Encyclopedia", where he suggested changing that definition of a second so that speed of light would be c=300000000[m/s]. notice that difference is only round 0.0692% but give's us some logic behind it.


===== distance =====
now how about a distance? my friend's mum had an interesting experience recently -- she bought a car from USA and took it to her home city. when she took a ride she noticed two things:
  - it's nice
  - everyone drives so slow today
even when she was driving in a city with allowed speed of 50[km/h] she had to pass every each car on her way. what was the problem? why everyone drives so slowly? actually it was other way around -- since it was American car, it was calibrated to show MILES per hour not KILOMETERS per hour, so in fact she was driving 50[mph], which in turn is around 80[km/h]... which is far more than the allowed speed.

everybody knows there are [[wp>kilometer]] and [[wp>mile]] units. fortunately [[wp>kilometer]] is far more common, since it is logical [[wp>SI]] unit, easy for computations. i've been once a witness of a talk like "aa - it's simple! 12 inches is a foot, 3 feet is one yard" and so on. then the question came: "ok. can you tell me please how many inches does 2123.2 yards have?". after a few seconds of silence someone else begin on the table at that time confirmed "this is true -- we think it is simple because we got used to it". imagine the same question using [[wp>meter]] and similar units! 1000[mm] is 1[m], 1000[m] is 1[km], etc... it's all about moving the comma to a right position -- couldn't be simpler!

but there is more! historically there were tens of different "miles" definitions. now it is much simpler, since in common usage are only USA/UK [[wp>mile]] and [[wp>nautical mile]]. the second is not [[wp>SI]] and is around 1.8[km] -- sounds strange, but this time it does have a meaning. using nautical miles it is simpler to calculate distances on the see, but let us leave the details.


===== holidays and weekends =====
making a survey on days off i'd expect that nearly 100% of working/learning people would say: saturday, sunday, new ears eve, christmas and so on. do you notice any pattern? most of our planet work in 5+2 shifts that covers the same days of a week! what is the problem? well -- have you ever complained about traffic jams when trying to leave city on friday afternoon? or maybe entering it on sunday evening?

it was annoying me for a years -- what is the problem to let people choose when do they want to have they days off? 5+2 is ok, just why these 2 must always be saturday and sunday? this makes life harder for all of us. leaving for a holidays -- traffic. going back -- traffic. being at the place -- many people. the key is that when weekend ends problems are gone! the main issue here is that we all try to do the same on the same time. if everyone choose some 2 days in a week to have it free distribution of people at holidays and at work would be also like 5:2 while keeping nearly constant load.

until recently the idea i've just presented was purely theoretical. since few weeks it is not. i've managed to reorganize my working days and hours so that i get up early to work, and get back late, but in turn having 2 extra days off during the week. it is incredible to see how it works when you get off from it -- you can do the shopping without long lanes and high traffic, since everyone are at work/school. you can go for a short holidays wherever you want, since everyone works at that time so except of yourself at the place there are just few more people how happened to take they days off at the same time.


===== conclusion =====
man are creatures of habit. we don't like changing habits and it is not quire natural for us to notice we actually do have them at all. but when you stop for a moment and see it from other perspective it becomes obvious -- it doesn't have to be that way and it's all up to us.