#but tbf why is time measured in 60s

[acedaniammx]

I usually don't stim but occasionally my brain will just be like "okay it is time" and then I'll slap my legs up to ten times a second for like half a minute

[ahiijny]

an interesting thing I learned today was that global warming might result in a negative leap second sometime in the future

(admittedly the earth's rotation is affected by lots of complicated factors so it might not be that clear-cut, but anyway)

so you may be thinking 'but leap seconds are like a single second? so short! who's going to notice?'

well tbf the impact from these leap seconds is going to be most strongly felt by high precision things like GPS or NTP servers whatever (and the poor devs who have to maintain the software lol) but leap seconds have historically caused unexpected problems in financial markets and all sorts of websites and servers as well, so...

in any case, I find all this really fascinating and pls bear with me while I nerd out a bit about this :P

so normally speaking, the Earth's rotation should be gradually slowing, because the pull of tides from the Moon and so on (though there are other influences too, like fluid flow in the outer core, the movement of Earth's crust, etc. so it's all very complicated)

until recently, the length of a day has been about on average 1-2 milliseconds longer than 24 hours (note that there are seasonal variations though).

1-2 milliseconds may not seem like much, but it adds up over time!

in fact, it's the job of the IERS to monitor the difference between UTC (universal coordinated time) and earth's rotation angle (UT1), and decide when to insert a leap second to prevent them from drifting too far apart

the current version of UTC (as defined by the ITU) requires the difference between UTC and UT1 to be no greater than 0.9 seconds. The IERS typically inserts a leap second when the difference grows to 0.6 seconds.

HERE'S A GRAPH

see, the difference between UTC and Earth's actual rotation angle keeps drifting. UT1 keeps falling behind UTC, so those vertical lines are every time the IERS inserted a leap second, to bring UTC and UT1 back closer together

since UTC is ticking faster than UT1 bc of Earth's rotation slowing, we typically need to insert positive leap seconds for when UTC gets too far ahead

positive leap seconds take the form of an extra time second 23:59:60, which happens at the same instant UTC everywhere around the world

historically, we've needed to insert a leap second every 1-2 years or so

it's not very regular tho, bc the Earth's rotation can vary in unpredictable ways. Even earthquakes and the filling of the three gorges dam had a detectable effect on the Earth's rotation.

but what's this? if you look back up at the graph above, you may notice that the graph seems to flatten out near the end there. Why's this happening?

here's ANOTHER GRAPH (with tiny text sorry)

the squiggly green line here shows the deviation in length of day relative to a SI day (i.e. 86400 SI seconds). Look for the ±0 ms baseline on the left vertical axis.

in the 1970s Earth's rotation was in the range of 1-2 ms longer than an SI day

but recently the length of a day has been shortening, and in 2020, there were a large number of days where the length of a day was actually slightly less than 86400 SI seconds! (mostly by less than a millisecond, but still)

2020 had 28 of the shortest days on record since 1960, and days in 2021 are predicted to be even shorter (note that the difference is on the order of milliseconds... but stillllll)

this is actually why we haven't seen any leap seconds recently. The previous one was in 2016. In fact this is the first time since 2003 when we will have had a 256 week period without leap seconds

and this in fact might cause some GPS systems to bug out hehe. In the widely used gpsd package, there was a recently reported bug "GPSD time will jump back 1024 weeks at after week=2180 (23-October-2021)". This bug happened bc the code author wrongly assumed that leap seconds would be more frequent :3

and if the Earth continues to speed up like this, the IERS may need to insert a negative leap second at some point in the future, to bring UT1 and UTC back closer together

this would take the form of the UTC clock going from 23:59:57 to 23:59:58 and then skipping directly to 00:00:00.

in the history of UTC there has never been a negative leap second, so needless to say software ppl aren't too excited at the prospect of this happening :3

so what's causing the earth's spinning to unexpectedly speed up?

there's been some research that suggests changes in the density and circulation of ocean temperature rises might result in a net transfer of mass to higher latitudes. but the predicted time deviation doesn't fully explain the changes we currently see

there's also the idea that ice melt results in water running downhill, resulting in a redistribution of mass closer to its axis of rotation

but at the same time, a redistribution of ocean mass to the equatorial latitudes would result in mass going farther away from Earth's axis of rotation

or maybe it's just Earth's crust and magma and stuff doing weird things again, who knows!

the Earth's rotational axis isn't static either; it can shift, and that might also change the effective rotational inertia

it's probably a complicated combination of a whole bunch of factors

but anyway, why do we even have leap seconds?

well the main motivation for leap seconds was when we switched from solar time to atomic time around the 1950s-ish. So before our clocks became accurate enough to tell the difference, we just said "yo, a second is 1/86400 of the time it takes for the sun to go all the around the sky, by definition" and that's good enough! the length of a day can vary by a few milliseconds from year to year but we wouldn't have been able to tell the difference.

but gradually timekeeping precision requirements grew so eventually in 1967 a second was defined to be "9,192,631,770 periods of the something something something caesium atom" which was way more precise and good for atomic clocks but bad for keeping the clocks in sync with the sun

so the concern was without leap seconds our atomic-clock-based timescale would drift relative the sun and then eventually we'd have solar noon when our clocks said midnight and vice versa

I mean, sure, that probably wouldn't happen for thousands for years, but procrastination is bad, ok?

but still admittedly leap seconds are somewhat controversial and there's plenty of Discourse™ about this, esp. in academic circles and stuff, so if any of you into that kind of thing here's one possible starting point :3

anyway some ppl have made some code to make predictions based on IERS bulletin A, so based on the latest Earth rotation measurements as of 29 July 2021, and whole bunch of (and I quote) "very large, probably unjustified assumptions"...

expect a negative leap second in the ballpark of June 2029 :3

[calliecat93]

Star Trek TOS Liveblog: The Man Trap

This will be the third time ever watching this one. The first time was when I was fifteen, and I wasn’t impressed. The second time was back in January and while I ranked it pretty low (2/5 IIRC) it was okay, but nothing great. Will that change now having seen the whole series, thus the new insight might change my opinion for better or worst? Well, let us find out~!

This is technically a McCoy episode, so it DOES already win more favor now that he’s my absolute favorite. First two times all I knew about him was that he was a doctor and... that was it. Seriously, McCoy needs more love in popular media and not just for the ‘I am a doctor, not x’ and ‘He’s Dead Jim’ jokes.

The first episode broadcast, and they get the McKirk dynamic perfect instantly. Mind you this was the fifth episode produced, but still this was the 60’s audience first time meeting Kirk and McCoy and this would be the first dynamic introduced to them. And right of the bat, it’s so good. Kirk teasing McCoy about his ex and the flowers bit, haha! Plus the fact that Kirk felt the need to mention that Nancy is McCoy’s ex in his Captain’s Log amuses me for some reason.

I didn’t appreciate how freakin’ amazing an actor DeForest Kelley was the first time around (and not the second time with this episode specifically either), but the way he performs McCoy’s clear anxiety, anticipation, and nervousness about meeting Nancy again... God I love this man~ Also McCoy’s real cute when he’s lovestruck, haha~

“He’s all yours Plum... Dr. McCoy” Jim is just enjoying every moment of finding out about Bones’ love life/messing with Bones over his love life and I love it XD McCoy’s face at that haha~!

Darnell, the first causality of Star Trek. Just missing the red shirt to make it all complete haha~

Sorry your flirting didn’t work out Uhura, but don’t worry! You’ll have better luck in an alternate timeline~!

Aww first McKirk fight. But hey, they make up like... five minutes later. Did I mention that McKirk is an underrated dynamic/ship (I did) ? Cause this is such good McKirk material.

I forgot how freakin’ creepy the Salt Monster is...

I SO wish that we’d had more of Sulu being a plant nerd in-show. Rand was also really fun in this one, which with how she’s treated in all of her other episodes... God she had so much wasted potential.

Is this the only time we ever see McCoy in his quarters? I need to look that up later... also I think I saw somewhere that he and Spock are neighbors going off their nameplates which of course they would be XD

Kirk talking serious business while casually eating some colored stuff on the bridge. Dork.

...okay yeah this episode is definitely hitting me harder this time than the last two times. Like last time I didn’t know about McCoy enough to either feel bad or be worried about him... while this time the ’OMG LADY IF YOU DO ANYTHING TO MCCOY I WILL RIOT AND NO ME ALREADY KNOWING WHAT HAPPENS DOESN’T CHANGE THAT FACT!!!’ feeling is now in high gear.

McCoy, despite clearly still having feelings for her, keeping himself together and not reciprocating Nancy’s advances because she’s a married woman. He’s a good man. I will admit to laughing when Nancy says that she likes him more because his feelings are stronger though, because OF COURSE McCoy’s feels strong emotions all the time haha~!

Considering that she’s under his command in The Undiscovered Country, I’d really like to have sen more Sulu and Rand friendship. It was cute in this episode~

Again, because I failed to appreciate how good of an actor that De was the first time around, I didn’t appreciate how well he did as McCoy whose really Nancy disguised as McCoy. He’s legit creepy with how coldly calculative and subdued (especially compared to how passionate and upfront that McCoy normally is in comparison), yet twitchy and unhinged due to the desperation for salt that the creature is. All the little physical motions that he does as they interrogate Crater, clearly on edge with said motions and body language at the possibility of being exposed. Acting as your character actually being another character acting as your character is not easy to do, but De absolutely nailed it. Why they waited until Season 2 to give him a starring credit I’ll never know.

Love how clearly Spock’s already suspecting that something’s not right with McCoy. When McCoy isn’t being an illogical, over-emotional human, he just knows that something is horribly, horribly wrong even this early on XD Too bad he got injured in the process and all, but meh not the worst that’ll happen to him.

Poor McCoy wakes up to his best friend telling him that his ex is dead while she’s screaming about him wanting to kill her and God what did he do to the universe to deserve this?

Okay admittedly McCoy not being willing to shoot when he’s seeing Nancy clearly doing something to Jim (even if he doesn’t know what) might have been pushing it a bit much... but tbf he’s still clearly shocked/processing what the Hell is happening, just woke up form being drugged, and struggling with his feelings plus he doesn’t like to harm anyone cause doctor and all, so... maybe pushing it but I can believe why he’s in denial despite what’s happening right in front of him.

Ah the one thing that can break Spock’s logical Vulcan demeanor and get outright violent even this early on: Jim being in danger. Glad we got that right first episode... fifth... whatever!

And McCoy kills the image of his former lover to save his best friend’s life even when she begs to him for her not to... again, what did he do to the universe to deserve this? But on the upside he chose to do it to save him so... can I count that as a McKirk moment? Yeah sure, we’ll count it even if it hurts.

Te ending is kind of solemn. McCoy’s clearly not over what just happened, and God who could blame him? Kind of a bummer that he got no real closure, and knowing him it’s just another scar that he’ll carry and keep covered up along with all the others. Hopefully Jim at least gave him some support.

So yeah... I honestly DID really like this better this time. It’s still not the best episode, but it’s by no means a bad one. I’d boost the 2/5 rating to a 3/5 rating and take it off the Least Favorite S1 Episodes list, but we’ll see how I feel when I let it settle and watch it again for the review. Either way... God McCoy needs a hug after this. Oh and I almost began writing a whole McCoy meta regarding this episode (and some For the World is Hollow... added for good measure) which got long enough to require it’s own post that I’ll get to soon. But yeah some nice McKirk, creepy salt monster, excellent DeForest Kelley acting, Sulu and Rand being cute, and it was a decent episode. Though IDT it was the bet to be the premiere once it would have been stronger if the audience had gotten to know McCoy’s character better prior, but that’s the business for you. Was very much worth looking at again~!