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The Unix timestamp will begin with 16 this Sunday

unixtimestamp.com

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Re: The Unix timestamp will begin with 16 this Sunday

#91

Post by flopunctro »

m-p-3 wrote: post #60
BoppreH wrote: post #46

Earlier quoted context omitted.

There is a very good reason to eventually abandon it: leap seconds. Unix time goes back one second whenever there is a leap second on Earth. It's extremely weird and IMHO completely ruins the purpose of a timestamp, but it's a compromise for backwards compatibility, since Unix time was created before leap seconds. This hack ensures that the number of seconds in a day remains fixed, an assumption of many systems at th…

Or lets say we colonize a planet with a significant time dilation (ie near a supermassive blackhole), how do you deal with this? Who has the canonical time?

AFAIK, there is no canonical time in relativity. There is the "local time", which is what your wristwatch shows, and the "time in place X", where X can be Earth, Mars, or some spaceship. These times might not be in sync, and they might even be distorted. Because, if place X is moving relative to you at a significant percentage of lightspeed, their seconds will be longer. Also, the further X is, the blurrier the concept of simultaneity becomes. Which makes the question "what time is it _now_ in place X" moot :)

Re: The Unix timestamp will begin with 16 this Sunday

#92

Post by moonbug »

thinkmassive wrote: post #88
shantara wrote: post #44

Earlier quoted context omitted.

In "Deepness in the Sky" a spaceship's computer is still running on Unix time many thousands years into the future. It is generally believed that the calendar starts with the first Moon landing, and only the main character as a "programmer-archeologist" discovers a small difference between it and true Unix time 0.

Vernor Vinge sounds like an intriguing author! “Most years, since its inception in 1999, Vinge has been on the Free Software Foundation's selection committee for their Award for the Advancement of Free Software.”[0] Since “A Deepness in the Sky” was written in 1999 as a prequel to “A Fire Upon the Deep” (from 1992), which do you recommend to read first? [0] https://en.m.wikipedia.org/wiki/Vernor_Vinge

Fire, then Deepness, then stop.

Re: The Unix timestamp will begin with 16 this Sunday

#93

Post by nvrspyx »

netmare wrote: post #90
nvrspyx wrote: post #38

Earlier quoted context omitted.

To add, Powershell: (Get-Date "1/1/1970").AddSeconds(1600000000).ToUniversalTime() or alternatively for your local time: (Get-Date "1/1/1970").AddSeconds(1600000000).ToLocalTime()

Heh... I've run into this bug myself recently. Get-Date '...' returns a DateTime object of Unspecified kind, i.e. neither Local nor Utc. By design, such objects are interpreted as Local by ToUniversalTime() and as Utc by ToLocalTime(). They essentially assume the inverse of themselves, for better or worse. Since the Kind property is readonly, to get the real UTC date you need: $naive = (Get-Date "1/1/1970").AddSecond…

Interesting. I'm using Powershell 7 (e.g. Powershell Core) and I'm not sure exactly which version number specifically, but the functions seem to work as intended on my Windows 10 machine.

Re: The Unix timestamp will begin with 16 this Sunday

#94

Post by numpad0 »

flopunctro wrote: post #91
m-p-3 wrote: post #60

Earlier quoted context omitted.

Or lets say we colonize a planet with a significant time dilation (ie near a supermassive blackhole), how do you deal with this? Who has the canonical time?

AFAIK, there is no canonical time in relativity. There is the "local time", which is what your wristwatch shows, and the "time in place X", where X can be Earth, Mars, or some spaceship. These times might not be in sync, and they might even be distorted. Because, if place X is moving relative to you at a significant percentage of lightspeed, their seconds will be longer. Also, the further X is, the blurrier the conce…

If relativity don’t allow time travel doesn’t it make time canonical? A clock on Earth from telescope might look jumpy but only in forward direction after compensating for distance I think

Re: The Unix timestamp will begin with 16 this Sunday

#95

Post by jrimbault »

iso1210 wrote: post #59

I remember staying up late (UK) at the Billenium (2:46 AM Sunday Sep 9th 2001), thinking that was bound to be the most newsworthy event of the week, watching the seconds tick past on a "while(sleep 1); do date" loop, with slashdot in one window, IRC in another, all running on an enlightenment window manager. 500M seconds later I was in Washington DC in a hotel, watching it tick up on an rxvt on my laptop, with HN in…

(guenine curiosity)

Why do you wait for these events ? Myself I consider these to be complete non-events.

Re: The Unix timestamp will begin with 16 this Sunday

#96

Post by withinboredom »

tgsovlerkhgsel wrote: post #57
jezze wrote: post #37

When we one day become a space faring civilization we will probably stop using the gregorian calendar because why would you use that on say Mars? But there really is no reason to get rid of the unix timestamp as a measure of time and this measure may stay around for a long time. This may mean that people in the future might consider 1970 as year zero where modern civilization began.

With Earth's day length becoming irrelevant, the 24 hour clock becomes irrelevant too, and the length of the sleep cycle may shift. We could eventually arrive at stardates with one starday being 100000 seconds. Of course, that would be just as arbitrary as simply keeping the 24 hours of 60 minutes each.

Humans have a remarkable circadian rhythm that does a pretty good job at defining a day as “24 hours.”

Re: The Unix timestamp will begin with 16 this Sunday

#97

Post by TheArcane »

dylan604 wrote: post #84
BoppreH wrote: post #46

Earlier quoted context omitted.

There is a very good reason to eventually abandon it: leap seconds. Unix time goes back one second whenever there is a leap second on Earth. It's extremely weird and IMHO completely ruins the purpose of a timestamp, but it's a compromise for backwards compatibility, since Unix time was created before leap seconds. This hack ensures that the number of seconds in a day remains fixed, an assumption of many systems at th…

Isn't a second just how long light takes to travel 299,792,458 m? Also, "since Unix time was created before leap seconds." I found this interesting for the simple reason I've never spent any time thinking about Epoch vs Leap Second histories.

And meter itself is defined as the length of the path traveled by light in vacuum during a time interval of 1/299,792,458 of a second.

So it's cyclic and doesn't make sense outside the earth reference frame

Edit: since 2019, 1 second is defined by taking the fixed numerical value of the caesium frequency ∆νCs, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1

So a second makes sense in the galactic scale at least as long as Caesium-133 is a stable isotope in that environment

Re: The Unix timestamp will begin with 16 this Sunday

#98

Post by dripton »

iso1210 wrote: post #59

I remember staying up late (UK) at the Billenium (2:46 AM Sunday Sep 9th 2001), thinking that was bound to be the most newsworthy event of the week, watching the seconds tick past on a "while(sleep 1); do date" loop, with slashdot in one window, IRC in another, all running on an enlightenment window manager. 500M seconds later I was in Washington DC in a hotel, watching it tick up on an rxvt on my laptop, with HN in…

A former employer's telephony software had a 9-character intstring field for the Unix timestamp, so there was a bug when it rolled over to 1000000000 in 2001. Pretty rare, I think. Unix timestamps back then were usually 32-bit ints, so good until 2038. And hopefully they'll be 64 bits everywhere that matters well before 2038.

Re: The Unix timestamp will begin with 16 this Sunday

#99

Post by fred256 »

maxnoe wrote: post #42
roland35 wrote: post #3

How exciting! 1500000000 occured on 07/14/2017 @ 2:40am (UTC), so it seems we'll have to only wait about 3 years until the next one!

A year is approximately PI × 1e7 seconds

"π seconds is a nanocentury."

https://en.wikipedia.org/wiki/Tom_Duff

Re: The Unix timestamp will begin with 16 this Sunday

#100

Post by wwright »

ericbarrett wrote: post #77
susam wrote: post #21

It is going to be at 2020-09-13 12:26:40 UTC. Python: $ python3 -q >>> from datetime import datetime >>> datetime.utcfromtimestamp(1_600_000_000) datetime.datetime(2020, 9, 13, 12, 26, 40) GNU date (Linux): $ date -ud @1600000000 Sun Sep 13 12:26:40 UTC 2020 BSD date (macOS, FreeBSD, OpenBSD, etc.): $ date -ur 1600000000 Sun Sep 13 12:26:40 UTC 2020 All such dates (in UTC) until the end of the current century: $ pyth…

The datetime package is one of the best things about Python, and dare I say one of the best general purpose calendar modules ever written. It’s just so practical .

It still can’t parse ISO8601 :(
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