125 Years of Longitude 0 0' 00" At Greenwich 429
An anonymous reader writes "This week marks the 125th anniversary of the International Meridian Conference, which determined that the prime meridian (i.e., longitude 0 0' 00") would travel through Greenwich, UK. One of the reasons that Greenwich was agreed upon 'was that 72% of the world's shipping already depended on sea charts that used Greenwich as the Prime Meridian.' Sandford Fleming's proposal of a single 24-hour clock for the entire world, located at the center of the Earth and not linked to any surface meridian, was rejected / not voted on, as it was felt to be outside the purview of the conference."
Happy birthday to 180th meridian too ! (Score:5, Informative)
And don't forget the 180th meridian that came with it. When you cross the 180th meridian, you have to set your watch back/forward 23 hours !
Quite a few people are unaware of it ;-))
http://adsabs.harvard.edu/full/1919PA.....27..416F [harvard.edu]
Not true for WGS84 (Score:3, Informative)
It is worth noting that in the coordinate system most used today (WGS84), this is no longer true.
See this [googlesightseeing.com] explenation or check google maps.
Re:Not true for WGS84 (Score:5, Informative)
Your link says nothing at all about WGS84. Here is one that does: http://en.wikipedia.org/wiki/World_Geodetic_System [wikipedia.org]
Re:Happy birthday to 180th meridian too ! (Score:3, Informative)
Re:125 MORE years until the US gets time... (Score:3, Informative)
Re:125 MORE years until the US gets time... (Score:1, Informative)
Actually the US currently drifts away from Greenwhich.
But on the long term you'll go around the whole plante and arrive at London Central at 9:12 on 23.03. 382038273920.
Re:Greenwich, UK? (Score:2, Informative)
Because there's also a London, Ontario.
Re:125 MORE years until the US gets time... (Score:4, Informative)
That's because of the George M. Cohan song "I'm a Yankee Doodle Dandy" [lyricsplayground.com] which includes the line "... born on the 4th of July."
The tablet [wikipedia.org] that the Statue of Liberty is holding says, "July IV, MDCCLXXVI". I've always known it as Independence Day or July [the] 4th.
Re:125 MORE years until the US gets time... (Score:1, Informative)
It's stone and not stones (although as an 'outsider' I'll forgive you). It's 14 lbs to a stone.
Re:We still live in the past (Score:3, Informative)
Re:It's because meters and feet are the same (Score:1, Informative)
Leap seconds.
The ONLY problem with that is that you need your time aware product to be updatable for leap seconds and that adds a few cents to your $100 GPS locator.
But missing out on leap seconds means the stars change location faster and we have to update all the astronomy books and astronomy software and astronomy hardware.
The costs are about equal.
It's the gadget manufacturers trying to offload a cost onto someone else.
Not just gadget manufacturers. There must be lots of software that has to care about leap seconds, and they are a pain. Especially for distributed software that relies on systems being in sync with each other. This is largely because of a lack of foresight on OS writers. Most systems use some kind of Unix style timestamps that have no concept of leap seconds, so either the time has to jump, or the length of a second has to be adjusted for a short while to bring systems back in line with UTC after a leap second. This makes timestamps a little unreliable after a leap second and software that depends on them (e.g. by rejecting updates with timestamps in the future) can fail. Where I work we have 24hr operations on a world-wide basis, but these are reduced as much as possible whenever a leap second is due, to minimize the damage from a leap second induced software bug.
There are basically three time standards:
o GMT: Based on the rotation of the Earth.
o IAT: Based on atomic clocks (or whatever the latest best clocks are).
o UTC: Adjusted to be an integer number of seconds offset from IAT, to bring it within a second of GMT (hence leap seconds).
Most of the world uses UTC (with a plus/minus for timezones). There is a US proposal to drop UTC all together, and live off of IAT. So what if midday at Greenwich starts to drift a little from 12:00:00, and ends up at at 12:01:00 in a hundred years or so? If you want to know what time a star will rise, or where exactly to point your telescope, then use GMT. Everyone one else can use IAT. UTC is a standard based on an affection for GMT but a desire for accuracy that causes more problems that it solves. Get rid of it.
Also, as far as I know there has never been a leap second removed instead of added, but it is possible. How much software is going to fail when that happens? Probably not much on a global basis, but it could include critical systems.
Re:It's because meters and feet are the same (Score:3, Informative)
What was it fahrenheit was measured by? 32 F = water freezes, 100 F = body temperature, 212 F = water boils?
For reference, 0F is when salt water freezes, 32F is when fresh water freezes, and 100F is human body temperature (or at least that of Dan Fahrenheit.) The boiling point of water was not taken into account for creating the scale, it was just placed upon the scale later on.
I will grant that your point remains intact however.
One neat detail about the Celsius scale making more sense: Originally it was reversed, as in 0C was the boiling point of water, and 100C was the freezing point. It was only 'reversed' years later and against his will (Well, I believe he was dead by then, but still.)
It should also be kept in mind that both Fahrenheit and Celsius scales were created before 'temperature' was really understood. At that point in history, heat and cold were both forces that were believed to exist separately. Today we know there is only heat and lack of heat, but at the time it was believed there wasn't really an upper OR lower bound on temperature, and the scales were made accordingly.
Once the concept of heat as energy was realized, and there was a lower bound (absolute zero) but still no real upper bound, a new scale for scientific purposes was made to match, called Kelvin.
NTSC came much earlier. (Score:5, Informative)
- Video. The PAL standard is better quality than NTSC (Never The Same Color), so why did the Americas adopt an inferior option?
That's sort of like asking why we adopted the clearly inferior analog STDV standard instead of digital HDTV. NTSC was standardized in 1953, PAL was not standardized until 1963. Naturally, PAL was the superior standard...it was based around technology that was ten years more advanced.
Re:125 MORE years until the US gets time... (Score:4, Informative)
It's also an official language of international diplomacy (it comes *before* Spanish translations on US Passports), and is spoken in a lot of North African and Caribbean nations, so you have more places available to comfortably vacation =)
Re:125 MORE years until the US gets time... (Score:3, Informative)
For God's sake, say it any way you want, and write it in ISO YYYY-MM-DD format. Since no-one in the world uses YYYY-DD-MM, it is perfectly unambiguous.
Personally, I'm constantly irked by the fact that, in Canada, when you see something like 05/10/2010, you never know whether it's month or day first. In general, I see DD/MM more often, but because of strong American influence, every now and then you get a form with MM/DD, so you always have to look out for that.
Re:125 MORE years until the US gets time... (Score:2, Informative)
I have some contact with Imperial units now that I'm living in Canada - gladly, not as much as it would be a little bit further south
You would have almost no contact with Imperial units in the U.S. The Imperial System wasn't put together until 1824, and the U.S., long independent at that point, never adopted it. You would instead have contact with English units, some of which were co-opted by the Imperial System.
I agree with both of you (Score:3, Informative)
Using the same base across all measurements is really convenient - parent is correct about that.
But GP is also correct in that it is super convenient for your measurement base to have many factors. A unit comprising 10 smaller units can be smoothly divided in half, but not in thirds or fourths. For that purpose, 12 is a much more useful number than 10. You guys are debating the orthogonal advantages of two different systems: both are correct.
So the ideal would be a base 12 metric system, with all units scaling by twelves and grosses, ideally paired with a base-12 arithmetic system.
Sadly, that's a pipe dream. The cultural inertia of base 10 is so strong we don't even think about it --- it makes the "strong" US attachment to imperial units look weak.