Eliminate time zones, while we're at it

Someone just edited the Wikipedia article on Swatch Internet Time to add a link to this TechRepublic article from from last year. The article doesn't say anything new, but it does talk about the problems with time zones and Daylight Saving Time that Internet Time was supposed to solve, which happens to be apropos to the DST post I wrote yesterday.

Saving daylight

It happened again today. I lost 4% of a day of sleep due to Daylight Saving Time. We didn't have it when I was growing up in Indiana; it just meant that all our TV shows shifted in their schedules. My mom also grew up in Indiana, which now has DST, but now she lives in Arizona, which doesn't; coincidence? Nobody I know seems to like it. So why do we have Daylight Saving Time?

iPhone and iPad apps

Apps in this post:

CalRep by Jacques Lafon (MuppetJack)

Calendrier républicain by Hachette Livre

TI:ME by Alexander Clauss

Geek Time Pro by reizverstaerker medienwerkstatt OG

I have more apps for iPhone and iPad. Since I've been posting about the French Republican Calendar, I'll post about those first. I've talked earlier about Calendrier, Salut et Fraternité for iPhone, Salut et Fraternité for iPad and revol-di. Now we have some more.

CalRep by Jacques Lafon (MuppetJack) is a universal app (meaning it is designed for both iPhone and iPad). Originally released October 2, 2012 (56202, CCXXI/1/11), version 2.1 November 5, 2012 (56236, CCXXI/2/15).  It is free, with $1.99 in-app purchase for the "complete version".  I don't know what that means, and I'm not going to pay before I find out. In addition to the current date, you can convert between Gregorian and Republican dates for any year after I. I found one bug: all the Roman numerals for years are wrong on the selector, e.g. the current year 221 shows CCXX, although on the iPhone (but not iPad) the year is also correctly shown next to the picture. It starts in 1792 as "Yr (1) / Yr I (2) / Yr II (3)…" It sends daily alerts, which I like, and you can set what time to receive them, although for some reason you can't get them before 9 am, which is late for me. The dates are calculated according to what I call the continuous rule,  which is the fixed rule that leap days are added before (not after) most years divisible by 4, which is continuous with leap days during the Revolution, although those were determined by the equinox rather than a fixed rule, so sometimes it's a day off from the equinox date in some years. It does not show the decimal time, but it does show for each date the month's calendar girl and a picture of the rural calendar name, although for today it shows the barbel fish instead of the cornflower (barbeaux)! (See previous post.) It also has links to Wikipedia articles, although some of them don't exist, as such. Unlike some of the others, it does not show decimal time.

Update: The CalRep app is no more. It has been updated to version 3.0 and renamed UniCal - Universal Calendar, with a new icon, and now includes a bunch of other calendars, including Chinese, Mayan, Hebrew, Islamic and Persian. (What, no Julian/Orthodox?) The year number bug has been fixed.  Also, you can now get alerts as early as 5 am, although it does not always work for me.  The years appear to begin on the equinox.  I just noticed that only half the day-names appear; every other day says "Free Version", so now I guess I know what the difference is.  Maybe that's why I'm only getting half the daily notifications. 56477.131 (Sextidi 16 Messidor an CCXXI à 1 heure 37 minutes décimales t.m.P.)

Calendrier républicain by Hachette Livre is also a free universal app, released on September 3, 2012 (56173, CCXX/12/17).  It converts between Gregorian and Republican dates, and also converts French day names (like Barbeaux) to dates, although you have to scroll through an unsorted list of 366 names! However, like revol-di, it only works for dates during the Revolution, itself. But you can use it to find current dates if you add 220 to the year. It also does not show decimal time.

TI:ME by Alexander Clauss is a 99¢ universal app, released November 2, 2012 (56233). It displays the current time in any of the following formats: decimal, local standard (24-hour, 12-hour or AM/PM), standard in other timezones, Braille, hex, octal, Swatch Internet Time (.beat), NATO DTG, trig (degrees or radians), or with numbers represented by symbols on the periodic table of elements. There are various settings for each clock.

Geek Time Pro by reizverstaerker medienwerkstatt OG is a 99¢ iPhone app, released August 9, 2011 (55782). It displays the time in binary coded sexagesimal (lights or 1/0), binary coded decimal (BCD), hex time or decimal time.

Duodi 22 Prairial an CCXXI à 2 heures 42 minutes décimales t.m.P.

MJD 56453.236

Mars Time

At August 6, 2012, 05:14:39 UTC SCET (MJD 56145.21850) the Curiosity rover landed in Gale Crater on Mars.  (SCET stands for Spacecraft Event Time, since it took until about 14 minutes later for the data transmission to reach earth.)  In Mars time that was 05:50:16 AMT (MSD 49269.24), about 15:00 local time.  AMT is Airy Mean Time, also known as Coordinated Mars Time (MTC), because it is the Local Mean Solar Time at Airy Crater, which marks zero longitude on Mars.  MSD is Mars Sol Date, and like Modified Julian Dates it is a count of Martian days, which are called "sols", but from December 29, 1873 (MJD 5521.5).

Another sol count is started whenever a craft lands on Mars, so that was on Sol 0 for Curiosity.  There is currently one other craft active on Mars, Opportunity, which was on Sol 3034.  Opportunity is near the Martian Prime Meridian, one hour behind AMT, but Curiosity is on the other side of the planet, 9 hours, 9 minutes and 40 seconds ahead of AMT.

Note that sols are longer than earth days by nearly 40 earth minutes but are divided into 24 Martian hours, so each hour, minute and second is 2.7% longer than those on earth.  Thus, the mission operators start their shifts 40 minutes later each day.  To keep track, they use a Java program call Mars24, which you can download from NASA.  By default it displays AMT and LMST for Curiosity and Opportunity, as well as MJD and MSD with two digits of decimal time.  You can also find more information at Wikipedia.

MJD 56148.377
MSD 49272.317

Leap second

On June 30, 2012 (56108.9999884), a leap second was added to Coordinated Universal Time (UTC) at the end of the day, to keep clocks within one second of Greenwich Mean Time (GMT).  23:59:59 was followed by 23:59:60.  This caused some computers to crash.  Since the software should have been able to handle this, the fault is clearly a bug in the software, similar to the Y2K bug.  However, it wouldn't matter if leap seconds did not exist.

I do not think that leap seconds are necessary.  They only are if you want to keep UTC within one second of GMT (UT1).  However, few use GMT today.  In the first place, it is the true solar time only for those exactly on the meridian of Greenwich.  Everywhere else has a mean solar time that differs as you go east or west of Greenwich, so before railroads every town had its own time.  But today we use unified time zones, which are (mostly) one-hour offsets from UTC.  The time in these zones in theory may be a half-hour more or less than actual local mean solar time, and in practice it is in many places much more than that.  Plus, many places practice daylight saving time for part of the year, adding another hour.  Even Great Britain is not always on GMT, and is considering advancing their clocks another hour to be in sync with the Continent.  Nobody actually follows solar time anymore.  So why should we care about GMT?

What would happen if we simply abandoned leap seconds is that UTC would start to drift away from Greenwich.  Every few years the difference would grow by one second.  Eventually, hundreds of years from now, the difference would add up to a whole hour.  But so what?  Local times today are already arbitrary and decided by governments.  If a particular region felt that the change had progressed too much, they could simply adjust their time zone when they chose.  This already happens all the time.

UT is not the only existing time scale.  Various other scales have been defined based up on the same atomic second.  The atomic second is based upon the ephemeris second of 1820.  Since the mean solar day is gradually getting longer, and varies from year to year, the day is slightly longer now than 86,400 atomic seconds, which is why leap years are added.  International Atomic Time (TAI) was synchronized with UTC in 1958 and is now 35 seconds ahead of UTC.  Terrestrial [Dynamical] Time (TT) is 32.184 seconds behind TAI and was introduced in 1984 to replace and be continuous with Ephemeris Time (ET) back to 1900, so it is currently 67.184 seconds ahead of UTC.  GPS time is 19 seconds ahead of TAI, and therefore currently 16 seconds ahead of UTC.  These time scales do not use leap seconds, so the difference between them is constant, but the difference between each with UTC is variable.  Simply eliminating leap seconds would fix UTC in relation to these time scales.

There has been discussion for the past few years about eliminating leap seconds, and this incident will likely increase pressure to do so.

MJD 56112.435