Time what is time

In case you didn’t know, UTC (Coördinated Universal time) and GMT (Greenwich Mean Time) are one and the same. I thought that everyone knew that, but recently, I spoke to people who find UTC confusing.


For quick navigation through the rest of the post use Ctrl+F codes:
Is there any difference? Why the hell use two terms?! (cf1)
The abbreviation UTC (cf2)
Other names for GMT (cf3)
Time Zones (cf4)
GMT difference (cf5)
Daylight Saving Time (DST) (cf6)
Calculating and converting time (cf7)

Is there any difference? Why the hell use two terms?! (cf1)

GMT is based on the local time at Greenwich observatory, near London. Hence the name Greenwich Mean Time. Greenwich is still used as the point through which 0° of longitude passes (yes, longitude is not strictly defined and Greenwich was just chosen for 0°).

Anyway, in the 1970s with the advancement of space technology, the use of satellites in calculating time more precisely began. Thus UTC was born. So UTC is based on GMT and isjust more precise. While there is a difference between GMT and UTC, it is disregarded in practice because the difference is like a nanosecond (satellites are more precise than an observatory on Earth).

GMT should have been abolished when UTC was introduced, but it wasn’t. Although, UTC is used for official purposes, GMT is still widespread. I dare say that it’s even more used. That is why I say “GMT” in the end of a post. WordPress, on the other hand, says “UTC”. That’s why time in the comments is displayed as something UTC+1/+2 (jump to cf6 to see why UTC+1 and UTC+2).

The point is that GMT, or UTC if you prefer, is international and, therefore, should be used always when there’s a possibility of that which you are referring to to be of global interest because we live in the world in divided into two dozen time zones and using GMT is the only way to prevent confusion. Every one should know the GMT difference of the time zone he lives in.

So yeah, GMT should have been included in this add of the live stream of The Desolation of Smaug première, which, by the way, sucked ass (the stream, not the movie). Not only that GMT was not included, but local abbreviations of time zones were used instead of GMT differences (jump to cf5 and cf7).
Nope, including GMT ain’t hard at all, yet again people are often too selfish to think about people outside their country or region, so crap like in the Hobbit add is common.

The abbreviation UTC (cf2)

As you can see, the abbreviation UTC is a little “clumsy” since the full name is Coördinated Universal Time, which would suggest CUT.
The French name is Temps Universel Coordonné, of which abbreviation would be TUC.
UTC was chosen as a compromise between CUT and TUC.

Other names for GMT (cf3)

What is the human nature? To complicate every little thing. Therefore, there are other names for GMT, none are used much outside a certain profession though.

One such name that I find shiny is Zulu Time. It’s not connected with Zulu people nor with Zulu language.
Zulu is a military name of the letter Z. NATO has a need of a quick reference to the international time zone. Z is the solution since it is only one character. You might encounter, dunno, 00:00z somewhere. It means 12:00 AM GMT and that the author was in a hurry. That is shiny in written language, but I do wonder how saying Zulu is quicker than saying GMT… or UTC.

Time Zones (cf4)

The Earth is divided into time zones. Officially, each time zone is covered by 15 degrees of latitude. Each time zone is based on the local noon of the central meridian of a time zone. Local noon is the time when the sun is in its highest position. The sun is in its highest position at 12:00 PM only at central meridians. The offset with the local noon can technically be only 30 minutes. For example, the central meridian of my time zone is 15°E. 16°E passes through the town I live in, meaning that local noon here is at 11:56 AM [during standard time, 12:56 PM during DST (jump to cf6 for DST clarification)].

I used the words officially and technically in the previous paragraph. That’s because, time zone borders are usually defined politically and follow a political border. A good example is Germany, which mostly lies in Central European Time Zone (GMT+1), but the westernmost parts of the country lie in Greenwich Mean Time. The whole country observes GMT+1 [+2 during DST (jump to cf6 for DST clarification)].
There are even territories that mostly or totally lie in a time zone different from which they observe. Central European Time seems to be very popular in Europe and seems like everyone wants to be in the time zone. Spain, Andorra, France, Monaco and Benelux are all in Greenwich Mean Time Zone yet they observe Central European Time. Okay, a few places in easternmost France do lie in Central European Time Zone, but the rest…

In the Pacific, countries chose to stay on certain side of the Date Line. New Zealand should be observing the easternmost time (GMT+12). Yet again, Christmas Island, Kiritimati, observes GMT+14 although it lies in GMT10 time zone. Basically, there are roughly 26 time zones currently and that might change at any time ’cause you never know when officials of a territory are going to decided to mess up the time zones. Just a few examples are Russia, which just abolished two time zones and China, a massive country that observers time of a single time zone (China Standard Time, GMT+8).

GMT difference (cf5)

Each time zone has its GMT difference or UTC offset. That’s why time zones are labelled GMT-8, GMT-5, GMT, GMT+1, GMT+9, GMT+12 or UTC-8, UTC-5, UTC, UTC+1, UTC+9, UTC+12 etc. If everything were perfect, with the rule that each time zone covers 15°of longitude, there’d be all in all 24 time zones ranging from GMT-12 to GMT+12. Each time zone west of Greenwich is labelled with a minus (hence GMT5 for New York) and east with a plus (hence GMT+1 for Berlin) because as you go east you add an hour and as you go west you take an hour. Note that local time zones may have GMT difference in hours and minutes, mostly hours and 30 minutes (e.g. India – GMT+5:30).

Time zones usually have abbreviation(s) other than just the GMT difference. Eastern American Time is EST (GMT-5), while Central European Time is CET (GMT+1), however GMT differences are preferred because you might not know the abbreviation and maybe even wouldn’t know where to start from. People usually recognize, dunno PST, EST and CET, but do you know what time zone JST is?

Daylight Saving Time (DST) (cf6)

Many countries or parts of countries observe DST, especially those in Temperate Latitudes. The point is to save daylight because daylight length varies a lot throughout the year in Temperate Latitudes.

How efficient DST is ain’t the topic of the post. I think I mentioned DST a lot in this post.

Anyway, DST is adding an hour to local time. Basically, local noon occurs at 1:00 PM instead of 12:00 PM at the central meridian. The names of the time zones change then. For example, Pacific Standard Time (PST) becomes Pacific Daylight Time (PDT) while Central European Time (CET) becomes Central European Summer Time (CEST). Although the same abbreviations are often use which only adds to confusion 😮

DST is variously observed in different parts of the world depending on the continent or the country. For example, DST in North America starts on the second Sunday of March and lasts till the first Sunday in November. In, Europe on the other hand, DST starts on the last Sunday of March and ends on the last Sunday of October. That’s the same every year, so don’t act surprised when the it’s time to move your clock.
It’s totally opposite on the Southern Hemisphere where the seasons are opposite.

The point is that GMT is not affected by DST. That’s why Pacific Time changes from GMT-8 to GMT-7 during DST and why Central European Time changes from GMT+1 to GMT+2 during DST.
The UK, on the other hand, which lies in Greenwich Mean Time… observes DST and during DST its time becomes British Summer Time (BST) which is one hour ahead of GMT.

Ironically, DST often lasts longer than standard time. That’s the case both in Europe and in North America, especially in North America.
So, time in the UK is often not GMT.

Summer Time is a term used for DST very popular in Europe (hence Central European Summer Time and British Summer Time). That term makes no sense because DST often lasts longer than just in summer (as I said, Europe itself is an example…).

Calculating and converting time (cf7)

They make it sound so easy at school. They give you the coördinates of two places and time in one, so you have to calculate the time of the other place. You base your calculations that 15° of longitude covers one time zone, which is one hour. Now, that is all well if the place(s) are exactly in the correct time zone (e.g. Paris is not) and if there’s no DST.

If the GMT difference (accompanied by the correct DST setting) is used to abbreviate time zone, all is indeed simple. All you have to do is subtract two numbers. That’s why I said that GMT difference should be used in abbreviating a time zone. However, crap like EST, CET, EET… is often used. That is especially confusing when DST is in effect, but not marked in the abbreviation (you can often see CET in July).
Lemme use Berlin and New York for an example again: Du bist ein Berliner und all of a sudden you wanna know what time it is in New York. You know the GMT difference of your time zone (you should know that whether you’re a Berliner, New Yorker, Moscower, Tokyoer or any other -er 😉 ), but you don’t know the difference between Berlin and New York, and all you have is the abbreviation EST. What the hell can you do with that?! However, if you had the tag GMT-5 instead of bloody EST, you’d know the difference between New York and GMT is five hours. Since Berlin is one hour ahead of GMT (GMT+1), you could easily say: Aha! 5+1, the difference between Berlin and New York is 6 hours! So if it’s 11 AM in Berlin, it’s 5 AM in New York (not necessarily though – scroll down a bit).

When I see that the live stream of The Desolation of Smaug is at 6:30 PM PT, I can make a reasonable assumption that PT stands for Pacific Time (which is usually abbreviated to PST or PDT…) because the première is going to be in Hollywood, which observes that time. However, when a seven year old Hobbit fan sees that the stream is at 6:30 PM PT… You can teach a seven year old tu subtract a few numbers, but you can’t expect him to know in which time zone Hollywood lies and how the time zone is abbreviated!

The easiest way to convert time is definitely a time zone converter. Although subtracting is quite easy, there’s less of a chance you’re gonna mess something, especially if the time difference is big and ranges from west of GMT to east of GMT [e.g. LA (GMT8) to Berlin (GMT+1) (Berlin again! Gosh, I must love this town 😀 )], if you just enter values in a time zone converter. That’s why, I always say Use Time Zone Converter to quickly convert the time under the GMT time I write.

Most converters can search cities. This eliminates the DST confusion since a decent converter should count DST according to the local DST rules. For example, if you want to convert 6 PM in Berlin to the local time in New York on March 15th, you’ll get the correct time of 1 PM because the converter knows that DST started in the US but not in Europe, so the time difference between Berlin and New York that day is 5 hours instead of the usual six.

Some converters, like the one on my cell phone, only deal with cities. So what if you want a specific time zone, say GMT? Search for a city in that time zone, of course. So, for GMT, we’re looking for a country that observes GMT all year round. One such is Iceland, so if you want GMT, search for Reykjavik. Note that London is not going to do it because the UK, unlike Iceland, observes DST.

Thank you for reading. If you wanna read more about time, you can read Time zones, my old post. Note that since I like typing 😀 I’m not sure how many things I said in both posts 😮

Well, in any case, despite these posts time is not the entity like it claims to be 😀

Posted on December 12th, 2013 at 23:52 GMT
Use Time Zone Converter to quickly convert the time


2 thoughts on “Time what is time

  1. Pingback: Smart(ass) phones | Nelandir's Independent Trading Co.

  2. Pingback: Naprijed-nazad | Nelandir's Independent Trading Co.

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