MapItOut: “How far could I live from X?”

The folks at IAmsterdam have released a map that measures distances not in miles / kms but in time. Select a spot + a means of transportation + a desired travel time and it’ll show you how far away (in time) you can get.

From what I can tell European countries such as Belgium, France, Germany, etc. are also supported but New York (USA) and London (UK) for example aren’t.

MapItOut →

Clock Experiments by Vasilis

Vasilis had some fun and created these experimental clock interfaces.

First up is the “Decimal Clock”:

If we had ten hours in a day, instead of 24, and if each of these hours had 100 minutes instead of 60, and if every minute had 100 seconds, our clocks would look like this, and the time would be …

Decimal Clock →

~

And there’s also the “WowClock”:

All numbers are built with 24 round digits. Each digit looks like a small clock, with two hands that can turn. Every time a number changes, for instance when 13:36 turns into 13:37, the hands of all little clocks start moving until the reach such a position that their combined pattern forms the new number.

WowClock →

Grid Time (or “Why are clocks in Europe lagging behind by 5 minutes?”)

Yesterday I heard on the news that clocks in Europe have started to lag behind on the official time. The culprit is a fluctuation in Europe’s electricity grid. Clocks, like the ones in your microwave, that are reliant on Grid Time are affected by these fluctuations:

Grid Time is a time measurement which is based on the standard grid frequency of 50Hz in Europe. Fifty oscillations in alternating current equate to one second of grid time. Frequency fluctuations lead to deviations in grid time. If the frequency is lower than 50Hz, the fifty oscillations last slightly longer. If, on the other hand, the frequency is higher than 50Hz, the fifty oscillations are shorter. Since one second of grid time always constitutes precisely fifty oscillations, the grid seconds therefore last slightly shorter or longer depending on the frequency.

Due to a disruption of the power system originating in Serbia/Kosovo since mid January 2018, a total of 113GWh of the energy production in Europe has been missing. Electrical generators in other European countries had to do more work, as they tried to cover this loss. This however has some side-effects:

The electrical generators of an electricity grid rotate more readily and faster when consumption is low. Consequently, they rotate with a higher frequency. Conversely, the electrical generators rotate more laboriously and with a lower frequency when consumption is greater.

With Europe’s grid running at a frequency slightly slower than 50Hz, Grid Time has started to drift off. This is known as Grid Time Deviation:

The Grid Time Deviation is calculated by comparing Grid Time with UTC time (coordinated universal time), which is determined using highly precise atomic clocks.

Ever since mid January 2018 this Grid Time Deviation has been building up. At the time of writing Grid Time Deviation is about -5 minutes (e.g. clocks are lagging behind by 5 minutes). You can check the Grid Frequency and Grid Time Deviation yourself on Swiss Grid’s frequency page:


Grid Time Drift, dd 2018-03-07

Usually the maintainers of the electricity grid adjust the frequency to keep Grid Time in sync with UTC:

The Grid Time Deviation is constantly balanced out. If the time deviation is more than twenty seconds the frequency is corrected in the grid. In order to balance out the time deviation again the otherwise customary frequency of 50 Hz (Europe) is changed as follows:

  • 49.990 Hz, if the grid time is running ahead of UTC time
  • 50.010 Hz, if the grid time is lagging behind UTC time

This time however they can’t keep up, as 113GWh is a huge amount of energy. Thankfully it didn’t drop below 47.5Hz, because then we’d be having blackouts.

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Prevent time drift in Docker with docker-time-sync-agent

Today, at work, a colleague of mine ran into some time issues with his Docker containers: the time was clearly off. Turns out it’s a common problem:

Docker’s daemon fails to update the VM’s time after computer wakes up from sleep. The result is that VM’s clock will be set to a past time. This inturn will make Docker containers use that time.

Enter docker-time-sync-agent:

docker-time-sync-agent is a tool to prevent time drift in Docker for Mac’s HyperKit VM. It listens to system wakeup event and runs a shell script (update-docker-time) that updates the VM’s time. Time sync can be triggered manually anytime by running update-docker-time.

Install it using this oneliner (if you dare copy-pasting it, that is):

$ curl https://raw.githubusercontent.com/arunvelsriram/docker-time-sync-agent/master/install.sh | bash

docker-time-sync-agent – prevent time drift in Docker for Mac’s HyperKit VM →

How and why the leap second affected Cloudflare DNS

At midnight UTC on New Year’s Day, deep inside Cloudflare’s custom RRDNS software, a number went negative when it should always have been, at worst, zero. A little later this negative value caused RRDNS to panic. This panic was caught using the recover feature of the Go language. The net effect was that some DNS resolutions to some Cloudflare managed web properties failed.

90 minutes later they had identified the problem and started rolling out a 1-character fix.

How and why the leap second affected Cloudflare DNS →

Carbon – A simple PHP API extension for DateTime.

$carbon = new Carbon('first day of next week');

if ($carbon->isWeekend()) {
    echo 'Party!';
}

echo $carbon->addYear()->diffForHumans(); // 'in 1 year'

Carbon is just a class which is designed to be used instead of DateTime. Due to extending DateTime, all DateTime methods are available to users of Carbon. Additionally, it implements a __toString method, allowing users to put it in place of string representations of date and time as well.

Installation possible using Composer, of course:

composer require nesbot/carbon

Carbon →
Carbon – Date and Time the Right Way →

June 2015 Leap Second

Today a positive leap second will be introduced, as per IERS announcement:

To authorities responsible for the measurement and distribution of time: UTC TIME STEP on the 1st of July 2015. A positive leap second will be introduced at the end of June 2015.

The sequence of dates of the UTC second markers will be:

2015 June 30, 23h 59m 59s
2015 June 30, 23h 59m 60s
2015 July 1, 0h 0m 0s

National Geographic has a good video on this leap second phenomenon:

The International Earth Rotation and Reference Systems Service adds a leap second every few years to keep the clocks we use to measure official time and the speed of Earth’s rotation in sync. But why do we need to do this? And what kind of problems could result?

Watch your digital clocks, they should seem to be stuck for a second at midnight (UTC) 🙂

Falsehoods programmers believe about time and time zones

  • Every day has 24 hours
  • Every day without DST changes is 86400 (60 * 60 * 24) seconds long
  • Every day in UTC is 86400 (60 * 60 * 24) seconds long
  • Week one of a year starts in January every year
  • If I know what time zone someone is in and they just tell me the date and local time, I can always use software to find out what time that is in UTC
  • DST always sets the clock back and forth by exactly one hour
  • Countries that observe DST begin observing DST in the first half of the year and end observing DST in the last half of the year

Be sure to click through and read a few more falsehoods, along with their explanations.

Falsehoods programmers believe about time and time zones →