Interstellar Civilizations & Time

Interstellar Civilizations & Time

This episode is sponsored by Brilliant Keeping track of time is tricky enough nowadays,
it’s a whole different story when your clocks and calendars don’t have 24 hours or 365
days, let alone run slower. But that’s barely the tip of the iceberg
of problems with time facing interstellarcivilizations. So today we’ll be closing out our fifth
season for Science and Futurism with Isaac Arthur, and I am your host, the aforementioned
Isaac Arthur. As we say good bye to 2019 and hello to 2020,
it seemed appropriate to discuss time so we’ll be looking at its impact on Interstellar Civilizations
today and we’ll open 2020 up next week by contemplating Time Travel. Of course Time Travel itself is a fairly ambiguous
term. It assumes time normally runs at a set and
uniform pace and that’s nothing like the case. Time runs slower in gravity wells and when
you’re moving fast, and we happen to live in one such gravity well and need to move
very fast to get to any others out in the galaxy in any sort of sane timeline. And ‘sane timeline’ is probably appropriate
because in many ways it’s not the flow of time itself that really matters, but rather
the effect all the crazy time issues will have on civilizations and trying to keep those
civilizations connected. If you think time zones on Earth are a pain
in the modern era of instant communication, that’s nothing compared to trying to handle
time lag issues on talking to other planets with longer days and years, let alone stars
years away in communication time. Now in science fiction this always gets solved
by FTL, faster than light communications or travel, though in truth that only fixes part
of the problem and makes some of it worse. Time zones on Earth are only a problem because
we have instant and cheap communication, prior to that it didn’t matter that it was midnight
somewhere when it was noon for you, because you couldn’t interact with them in real
time. Even in my youth when long-distance phone
calls were rather pricey, the time zone thing wasn’t as big a deal because you didn’t
casually interact with other time zones much. With free long distance calls, remote offices,
and of course the internet and social media, we now have to deal with time zones all the
time. Right now, it wouldn’t really matter what
the day length or year on some planet around Alpha Centauri was, because we’re not talking
to a colony there real time, but on a four year lag, so it’s like sending someone a
very delayed letter or email. If you had instant FTL communication, then
it matters that they have a really different day and year. Of course we don’t have Instant FTL communication,
and aren’t likely to ever have it, indeed we don’t have instant communication even
here on Earth, it’s just so quick that you don’t notice the lag much. We’re mostly interested in interstellar
civilizations today, but it’s worth considering how colonizing our own solar system will alter
our attitude on time and interplanetary civilizations will influence how the interstellar ones develop. Let’s address the elephant in the room though. Without FTL, it doesn’t seem realistic to
have a galactic empire in the classic Space Opera sense, as we looked at in Interstellar
Empires. The Galaxy is a hundred thousand light years
across, meaning a message from one side to another takes a hundred thousand years. We’ll try to look at some ways for doing
that anyway later on, but for now it’s worth remembering that civilization, especially
in this context, doesn’t mean something centrally-run from some capital planet. Colonization of the galaxy doesn’t rely
on galaxy-wide coordination anymore than colonization of this planet by stone age tribes relied
on them all getting together to plan things out. So we do want to consider ways that might
allow cohesive civilizations like we generally have nowadays but we don’t want to limit
ourselves to thinking of them as a prerequisite for interstellar civilization. A developed solar system is an immense place,
even compared to a planet, and civilization got on just fine on a single planet prior
to the radio and telephone being invented, so we’ve no reason to assume the galaxy
would be a chaotic mess just because it was composed of essentially sovereign solar systems
who only have limited exchanges with neighbors. But let’s talk about the time issues within
solar systems, interplanetary civilizations. No naturally occurring solar system will ever
have two planets with roughly equal year lengths for a starter, as you can’t have stable
orbits occupied by two large bodies, with the exception of double planets, and those
will have quite atypical day lengths compared to Earth, from tidal locking, like our Moon
has. The only planet with an even vaguely close
day length to Earth is Mars, where its 37 minutes longer and you’d lose about a day
a month. That would be awkward for a lot of communication
as teams doing shifts on Earth and Mars, say 3 daily shifts, are going to have things cycle
around, so the morning shift in both places can’t coordinate more than a few days in
a row as the folks on Mars will get up 27 minutes later each day. That’s the easy case too, though in some
ways both the Moon and Venus are easier, the Moon has a day and year a month long, and
is in near-instant communication with Earth anyway, so is probably just going to use Earth’s
calendar. Venus and Mercury both have days months long,
and essentially useless for human-activity based time keeping. That will happen on many Earth-like worlds
around orange or red dwarf stars to, which is most stars in the galaxy, as even if the
day were about the same as Earth’s, the year might be just a few months or even mere
days long. Back around our Sun, early asteroid mining
efforts, which are likely to predate any major colonization of other planets anyway, aren’t
likely to want to use the rotation or orbit of a given asteroid as a reference point. Asteroids typically rotate several times an
Earth-Day and they’re small places among a hoard of other objects with different rotation
periods and orbits. Now you might use some major object like Ceres
or Vesta in the Asteroid Belt as a hub for activity and standardize to its local clock,
but that would probably be more likely for something more classically planet-focused
or concentrated like moons around a gas giant. Also we have to consider how space colonization
is likely to roll out in our solar system, which is to say we’re more likely to build
worlds than terraform them, via rotating habitats, and those can have day lengths of whatever
you want. There’s an assumption that Martian colonists
will start their own calendar up and maybe they would, but nobody else really has any
motivation to do so. Time keeping on Earth has to do with human
biology, adapted to Earth, and biology in general for stuff like growing crops. There’s no fields or fertile river deltas
out there for us to go farm, we’d be doing everything inside domes or artificially lit
and environmentally controlled facilities and we can regulate those to our tastes, presumably
Earth-standard – at least until living under Martian daylight becomes routine – see Springtime
on Mars for more on that. So you’d probably end up with everyone using
Earth-standard for exchange between places, and probably internally for most places too. Though that might alter a bit too. We’re coming up on a leap year in 2020 and
I could easily imagine those being gotten rid of in some standardized system. You also presumably need to pick a time zone
that was the official midnight everyone used. Metric doesn’t work well for time units,
or rather decimal doesn’t, folks often confuse base 10 with metric, which just happens to
use it. Our time measurement for days is still in
base 12, two 12 hour periods divided into 60 minutes, or 5 times 12, and 60 seconds,
again 5 x 12. There’s also the Jiffy, a 60th of a second,
but we usually switch back to base 10 for that and use hundredths or thousandth or billionths
of a second. There’s really no natural system that smoothly
lets you use the same unit for days and years, though, and in an era of computers it’s
not such a big deal, as they can rapidly convert times and dates for folks between time systems. Earth’s got billion of people on it who
will never have a motive to change calendars and by the time you’d have billions of folks
living off Earth, they’d be all over the place on different and awkward local times
anyway. Indeed the place most folks are likely to
live off Earth early on is in Earth Orbit, where the ‘day’ is a couple hours in low
orbit and in the higher orbits it is longer but the Sun is almost always shining with
noon-time brightness, since you spend little time in Earth’s shadow in high orbits. So possibly excepting Mars, nobody really
has a motive to use local timekeeping for regulating human interactions. You’d still have them, folks on Mercury
obviously will care when the Sun is rising or setting and doubtless develop local terms
for it, in their case something more akin to our month, as it takes about 2 months for
a day to pass on Mercury and they have no moon for a local month either. Once you get out far from the Sun though,
it gets less important what the Sun is doing since you really don’t see it, you might
have observation domes to go out and see the stars and look at distant Sol but you’re
doing your living indoors, even if it’s some massive habitat with whole forests and
parks inside it being artificially lit. Now while I’d imagine we’d send out interstellar
colony efforts within a generation or two of when it becomes practical to try it, in
terms of success odds and costs, you’re not likely to see big push for that until
most of our solar system has been utilized, including all the millions of minor planets
inside it. A handful of test colonies around other suns,
delayed in growth by centuries of travel time and without easy access to the industrial
might of our home system to expedite growth, are unlikely to be the ones setting standards
on timekeeping, and the issue is likely to be addressed before they are a major factor
in deciding. So too, while some colony on a world under
an alien sun might adopt some 26 hour day and 362 day year it had locally, we shouldn’t
assume that system would develop using that, because they’re not likely to start colonizing
that system with that planet. As we discussed in the Life in a Space Colony
Series, a colony ship arriving in a new system with an Earth-like planet, for a given value
of Earth-like, does not just go land there. You do your colonizing backwards, starting
in space and building up your industrial might and colonial support before going down and
terraforming some planet, a process of centuries at a minimum, and they will have spent decades
if not centuries traveling inside a spaceship that is much the same as any habitat or space
station they’d build there. Indeed even once that planet is terraformed,
they will likely have had their off planet population grow so much during that time that
they never had most of their population on that planet, so why use it’s natural calendar? Even if they left Earth planning to focus
on terraforming the destination planet, those folks will have lived in an artificial habitat
for generations and the eventual colonists might not find a planet all that attractive,
compared to just building O’Neill Cylinders or similar, a far faster and easier process
anyway. Such being the case, why change time keeping
methods? Now if they wanted to, they might slowly change
the ship from emulating Earth to Planet X while en route, they are likely to know a
lot about the destination, especially how long that planet orbits and rotates and what
its gravity is, so if they’re going to a planet with 90% of Earth’s gravity that
rotates every 26.7 hours while orbiting a dimmer orange dwarf star every 165 of those
26.7 hours days then they might gradually shift the ship’s internal environment to
match those, especially since it will help things besides humans adapt, like all the
flora and fauna you plan to transplant there. Which is also another reason to keep your
various habitats to Earth-normal times, our ecology is adapted to it and it’s probably
easier to mimic it than alter things to different setups. Still, all these various interstellar colonies
might alter to a local time setup simply to acknowledge that it might happen eventually
and they really are going to be rather isolated there anyway. They might all keep using the Earth Year for
official dating for communicating to other systems but they could also just as easily
do that in something metric like mega-seconds, about 12 days, or gigaseconds, about 30 years,
and just have some official Day 0, or Second 0 everyone used. If you’re curious, we’d be in the 64th
gigasecond of the AD calendar, megasecond 746 when the video came out. Of course the problem is that if they start
their clock before they leave Earth, when they arrive it’s going to be running slow. Which take us into the other big problem with
interstellar civilizations and time, which is relativity and how long such trips take
even when moving at relativistic speeds. The closer you get to light speed the more
time slows down, though in truth we’re not likely to ever have ships where it slows down
to such a significant factor that folks living on them feel like they were fast forwarding
through time. The same applies to general relativity, the
slowing of time from being in gravity wells or on an accelerating ship. Time runs a bit slower at your feet than at
your head, and a good bit faster on Mars, which has weaker gravity and is also further
from the Sun’s gravity. Time runs fastest in the intergalactic void,
particular the Cosmic Voids, the big empty spaces relatively devoid of galaxies, and
slowest near the center of galaxies, or of course, near black holes, which are at the
center of most big galaxies too. This difference is minimal though, even in
extreme cases, but starts mattering when dealing with really long time scales. But it is calculable so it just means folks
have to adjust their clocks or timestamps on interstellar correspondence. Thing is, what date do you actually use? A ship leaving Earth in the year 2020 and
arriving at a destination in our year 2200, having traveled at 20% of light speed, looking
at their own clock, might see that arrival as being in the year 2196, having experienced
about a 2% slow down in time during the voyage. They will also have traveled 36 light years,
meaning the signals they’re getting from Earth when they arrive don’t say 2200 AD
anyway, they say 2164. One might argue, especially if everyone wants
to keep to some standard time-keeping system based off humanity’s homeworld, that maybe
they should say that it is now the year 2164 on their arrival, rather than 2200. Of course to everyone who was awake for that
trip, quite possibly all the way from Earth if life extension technology has improved,
has still only experience 176.4 years of travel, not 180. Needless to say this only gets exacerbated
by longer flight times and higher speeds, but it also gets worse if we start contemplating
subjective time experienced. If you’re born in the year 2000, and got
on that ship, you’d be 196 when you arrived, so how old do you say you are and when do
you celebrate your birthday if you do decide your clock is the one that matters? Time was running 2% slower on your ship, so
if you were born on January 1st 2000, your 21st birthday, in personal time which is what
you age at and experience, was not on January 21st of 2021, it was on January 7th, but if
you checked the clock back on Earth, based on signals to your ship, it’s going to say
it’s January 1st on March 14th, because you’re 73 light days out from Earth somewhere
in our Oort Cloud, though your own clock on the ship would say it was March 5th, since
you’ve lost about 9 days to Einstein at that point. This is all assuming your ship instantly accelerated
too, which it won’t have, but it makes the already confusing math a bit easier. And of course that’s when you’re getting
all your mail from home, and it’s rather unlikely you’ve stopped corresponding with
friends and family entirely, or watching the news entirely. You’re still waiting for your favorite book
or show or film to come out, and you have to go by Earth date’s for all that. So you basically have 4 clocks you watch,
the atomic clock marking how much time has actually passed on that ship, the radio clock
from home telling you what the date was when that signal left Earth, the computer one telling
you what the calculated time on Earth is right now, which is a rather debatable concept,
and the one telling you what the date would be back on Earth when a message you sent right
now actually arrived, if you plan on sending a happy birthday message or gift you bought
online to friends or family back home that you wanted to arrive on time. Now if you plan to stay on that ship after
it colonizes that planet and starts running trips back and forth to Earth, you’ve got
to add in some more clocks telling you what the date on that colony planet is. Folks running some circuit of destinations
on interstellar trade routes might go rather nuts trying to track such things, if we didn’t
have computers they could set reminders on and rely on the computers to inform them. You also definitely need to track shipboard
time too since you’re likely to have all sorts of parts and software that have time-sensitive
maintenance and replacement requirements. Plus you’ll want an onboard atomic clock
to compare to clock signals from various systems to calculate your position and trajectory
with high precision, same as we do with GPS location systems. Speaking of computers, there’s more than
one way subjective time can get messed up besides Einstein. Needless to say, you might lose a lot of personal
time by opting for some sort of deep freeze or suspension technology, and that would shut
off your biological aging presumably or slow it, see Sleeper Ships for details. You might do this even if you have effective
immortality from radical life extension technology simply because you don’t particularly feel
like experiencing your decades long journeys. Now in discussing life extension I generally
dismiss the idea of being bored, I’d need a few lifetimes just to get through all the
books on my pending reading list, during which I imagine that list would expand faster than
I could read it, but at the same time there’s probably a realistic limit on how much life
you can experience in a mostly human form before you fill up your brain, and even with
memory enhancing or compression alterations to that brain, I’d tend to doubt anyone
who had actually experienced tens of thousands let alone millions of years of time would
really qualify as human anymore, simply by the weight of all that time and experience. I would doubt you could maintain sanity all
that time, at least in the sense of human-normal behavior. But that brings up mental augmentation and
realistically we’ll probably have a lot of that available long before interstellar
travel is more than a novelty a very rare few have experienced, indeed likely before
anyone has. There’s a lot more options to mind augmentation
than simply raising your IQ, but when we’re talking about super-intelligence we generally
classify it in 3 major types. One is Quality superintelligence, which is
a bit abstract but essentially why one human is smarter than 10 chimpanzees, even though
they’ve got more total brains. Another is networked intelligence, which would
basically be making those chimps smarter by wiring their brains together, though more
likely by creating a new distinct 10-chimp single mind, hive minds being one example
of networked superintelligence. The third though is Speed Superintelligence,
where you haven’t actually made someone smarter, just sped up the rate they think
at. You might do that by replacing their synapses
or neurons with transmitters that were identical except for transmitting at light speed, rather
than at roughly the speed of sound or slower as ours do currently. If you made such a switch, you’d be experiencing
time around a million times faster, in terms of your thinking, as you currently do. Now one might argue someone who sleeps 8 hours
a day and is awake for 16 is experiencing less life everyday than someone who sleeps
for 7 and is awake for 17, they are awake one hour or 6.25% longer each day and experience
23 more days every year. Whereas someone who sleeps 9 hours a day and
is awake 15 experiences 93.75% as much time, and if we’re only counting conscious time
that would match someone traveling at a third of light speed, in terms of time dilation. That’s obviously a pretty debatable point
as sleep is not the same as shutting someone’s brain off and since its part of what keeps
you healthy, you’re not likely to get a longer lifespan, even subjectively, by cutting
down on your sleep. Of course we might be able to rewire people
so that they did not need sleep to be healthy and mentally agile, and it would get hard
to argue that someone who was conscious and not groggy 24 hours a day, 365 days a year,
had not experienced 50% more life than folks spending a third of their time asleep, 548
subjective days per year. More so if they’re on some spaceship far
from Earth’s clocks and calendars – or love coffee, the original life extension technology. But with all that mental augmentation in play,
they might be able to slow or speed up their personal time quite a lot. Indeed they might slightly speed their consciousness
to exactly counter-match whatever the relativistic time dilation on their ship was. Time running 10% slower from moving at 42%
of light speed? Boost your subjective time up by 10%. Normally we think of slowing subjective time
on spaceships so you don’t experience it, but you might go the other way too. Indeed you might do this on planets with shorter
days, just make up that missing hour in a 23 hour day by accelerating everyone’s thinking
speed by a few percent. Now on the civilization side of things, all
this weird time raises issues. Let’s consider something mundane like paying
people’s salaries or calculating what grade a kid is in or what your wedding anniversary
is or when your interstellar mining corporation celebrates its 1000th anniversary with a big
marketing campaign and discount. With all the complexities we saw for space
traveler’s it’s easy to imagine folks who traveled a lot between stars would just
shrug and say “I’m pretty old” but it’s a whole different story if they’re contemplating
their paycheck, how many years they’ve got on their pension, what sort of compound interest
they’re getting on investments, and how much taxes they should be paying. We wouldn’t tax someone more or less income
tax because they were asleep, more or less, but what about someone in hibernation for
a trip? Or not for a trip, just on Earth. And before you say no, let me point out the
obvious tax dodge of owning stock in a company for a decade while spending 9 of it on ice,
paying only a year’s worth of taxes, incurring no expenses besides your freezer bill, and
emerging with a decade of earnings. Or alternatively, going on a five-century
voyage on ice for all but a year of it, getting home and being offered a year’s salary,
and paid in 500-year old values, with nothing for inflation or adjustment for any standard
of living increase during that time. You might say you deserve all 500 years of
that pay, or maybe the 400 that passed on that ship as it flew around at relativistic
speeds, but also keep in mind that someone else might be accelerating their subjective
time and demanding ten thousand years of pay as they experienced 10,000 years of consciousness. And it might be a fair demand too, if they
had to do it to perform their duties. Now we could handwave that off as not relevant
in some future utopia of immense prosperity, but there’s bound to be parallel examples,
we’re just using modern concepts, and mostly to highlight that there’s not any clear
and obvious approach. So different places might use different standards. You get on board some ship to serve as a crewmember
on a thousand year voyage to a different pocket of space and that ship’s captain says he
pays on ship-time, annual salary, but at your destination they expect you to pay income
taxes on the voyage if you plan to trade there, for all the local time you spent inside their
territory, while your home system is still taxing your assets using their own method,
and the interstellar trading guild you’re with expects you to pay them their dues based
on your ship’s clock but let’s you treat time in hibernation at a discount, say one
tenth of the ice-time counts, whereas your last guild charged none for hibernation but
expected you to have a tamper-proof chip in your head that measured your subjective time,
if you boost your thinking up to 10x normal speed, they charged you 10 times as much. Makes one wonder what overtime at work might
mean in such situations too. Now FTL makes this even more confusing, since
it opens the door on causality violating events, but in the long term all these time tracking
issues get worse. How historians would track the timelines on
some ten-thousand year long war operating over a thousand light years and a million
worlds is going to be beyond confusing, especially as battles might be continuing centuries after
a cease fire. Very stable and long-lived societies might
be able to form non-FTL empires stretching light centuries, just because they don’t
really need to write home for directions much as their society isn’t changing on a generational
basis and differently on each planet. But they also might have figured out some
perfect and stable society, there may actually be such a thing in some objective and mathematically
provable sense and regardless they might feel like they have it or close approximation. They may also get around light lag coordination
issues by having set protocols for how everyone acts in a given scenario, like emergency fleets
scramble to a preset coordinate to rendezvous with other fleets from other systems if a
given event occurs. Those might get rather complicated since the
ideal rendezvous point for given fleet elements would be time-sensitive and dependent on where
an enemy or disaster occurred, which they would all observe at different times and have
different travel times to react too. Trying to have a senate or parliament on an
interstellar scale might be beyond tricky too, considering a representative elected
and sent to the capitol might take several centuries to arrive, presumably begin their
term of say a decade, while getting orders from back home from political parties now
in control who didn’t even exist when they left, and arrive back centuries later to be
lynched. Time lag being what it is, you could easily
have all sorts of legal necessities too such as trials in absentia or hearings to decide
what to do with someone’s property who was originally only going to be gone a couple
decades for a quick jaunt to their nearest neighbor system but due to some unforeseen
event or change of heart got detoured and now you have to figure out what to do with
their property and its back taxes, with each system having different rules and those changing
every century or so. Some folks have suggested you might just have
civilizations freeze themselves most of the time to allow a net experience of time that
was slowed down, thus allowing a potentially larger civilization, but I don’t see that
working outside a special case we’ll get to in a moment. Another notion is that your interstellar civilization
might really just be the trade ships and their proxies or representatives in various systems,
as they’re the only ones who really need to care about what’s going on between star
systems much and would experience that slowed down time anyway and thus might be a stabilizing
or conservative factor, something along these lines is discussed in Alastair Reynolds’
novel “House of Suns” one of my favorite novels and one that deals with light-speed
limited civilizations trying to deal with millions of years of time passing, or the
people who travel between those civilizations and never visiting the same one twice since
they’re always gone by the time they return there on their galaxy-spanning voyages. Amusingly in the truly long term some of these
problems go away, presumably in part because they’ve just had a ton of time to figure
out what works best, but as we discussed in civilizations at the end of time, post-stellar
civilizations might camp around black holes, where time runs slower, and take advantage
of ultra-cold computing to run hyper-efficient but slow computation or thinking. For such civilizations the light lag issue
isn’t such a big deal because time is subjectively running at a miniscule fraction of the rate
it used to while every galaxy has either merged together or flown over the cosmological event
horizon. If you’re running at a billionth your normal
thinking speed, and so is everyone else, a hundred thousand light years, and a hundred
thousand years of message delay, only feels like an hour. And while life moves at a snail’s pace,
it’s still way longer subjectively too, those civilizations we discussed as existing
in post-stellar time could potentially exist for billions of billions of billions of billions
of years, so even at that’s snail’s pace of subjective time they still experience timelines
that make the current age of the Universe seem like an eyeblink. Of course time and entropy still take their
toll eventually, even if you can make such ultra-cold and slow civilizations work, and
you might start thinking about wanting to move to new Universes if they exist, or if
you’ve figured out time travel, go colonize or invade your own past, and we’ll look
at how a time travel capable civilization would work next week, if time travel was possible,
and if any sort of coherent civilization might be able to exist if it did. As we wrap up the Holiday season, let me give
you a hand knocking something off your holiday to-do lists. Gifts! If you’re watching this show, you probably
tend to feel like I do that knowledge is one of the best gifts you can give someone. If you know someone who likes to solve puzzles
or find out how things work, I’ve got a Brilliant gift suggestion for you… Brilliant. Brilliant is an online learning community
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a good signal while traveling for the holiday season. This year get the gift of knowledge for your
loved ones by gifting them Brilliant, it’s such a fun way to nurture curiosity, build
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career. Go to and grab a
gift subscription to help your loved ones finish their day a little smarter. So while we do have a livestream Q&A this
Sunday, today wraps up our episodes for the year, and I wanted to thank everyone for joining
me for yet another year of Science & Futurism. If you’d like to help support more episodes,
I’d be very glad to have your support on patreon, or through any of our other donations
methods you can find on our website, And of course we do have more episodes coming,
starting 2020 off on January 2nd with a look at Time Travel, then the week after that we’ll
explore Alien Conspiracies, and the sorts of aliens that might be conspiring and why,
in Conspiratorial Aliens. Until then, thanks for watching,
and we’ll see you next year!

100 thoughts on “Interstellar Civilizations & Time

  1. as for paying taxes on income, that one should be a little easier.
    you pay taxes on income generated at the location of the income.
    if you are paid on board your ship for time you're awake doing work, you pay taxes on that income in that location for the money you earn. You have passive income or investments in your home system, ostensibly being managed there, will be taxed there, on the income generated at that location.

  2. In regards to multi-system governments:

    It’s likely that each system would end up as an independent state in a federation of systems which keep a council or senate to deliberate group actions like national defense.

  3. When I was in high school I made a metric time unit that was equal to the time light in space traveled 1,000,000 km. It's 3.335646 seconds. It doesn't have a practical use, but I figured when people were living on different planets it could be a standard.

  4. Happy New Decade. Thank you for your hard work.

    Final comment of 2019 to all hard working professional astronomers – Maybe its Aliens? – Maybe…. just maybe…

  5. I like to imagine that interstellar civilisations would probably only work if civilisation itself happened very slowly, sort of like the Race from Harry Turtledove's Worldwar books. The Empire they rule has been around for 100,000 years, and technology and social change are all so artificially slow that the travel lag between planets or star systems hardly matters.

  6. I knew someone who worked one of the Mars missions for NASA; their group kept 24-hour Mars time, dividing up the Martian day into 24 Martian hours of 60 Martian minutes, rather than 24 Terrestrial hours with some change left over — and man, did I covet his Mars-time watch! If I had to bet a nickel on it, I would expect that simply as a matter of psychological/sociological inertia, we'd keep local 24 hour time on any planet with a day of an appropriate length to make that convenient.  On tidally locked worlds, or those with inconveniently long or short days, I might put that same nickel on keeping Earth time and ignoring the local day.  The day, minute and hour as currently used are units of time with which we are familiar, and won't want to change without a terrific reason to — witness all the times that decimalized time has failed to catch on, even though in principle it would be sensible (or at least not ridiculous).

  7. Surprised you didn't mention the Julian Day/Date system, which is currently the main solution used for computational purposes by scientists.

  8. The only reason I use time is for when my grow room lights go on and off. Brains don't need technological augmentation to do things you mention. These can be achieved through "meditation" but I don't mean sitting there cross legged saying I am meditating. I mean every breath, every moment, every thought with God. Too many people could not believe even if they saw. Especially these days. But if he who sees and believes is blessed then how blessed must he be who believes without seeing. That's why I see proof, because I already believed. Then I tell you I saw proof and if you believe without seeing proof then how blessed you will be…

  9. I'm a little surprised that you didn't mention time and navigation. All that it takes is a minor timekeeping error (due to speed or an unexpected gravity anomaly or simple computer glitch) and you miss your destination completely (or smack into something else early).

  10. "Now in discussing life extension, I generally dismiss the idea of being bored. I'd need a few lifetimes just to get through the books on my pending reading list, during which I imagine that list would expand faster than I could read it."
    I'm like Isaac Arthur and CGP Grey.

    Running out of new things to do isn't as bad as never being able to do anything at all ever again, even to care or even realize you can't do anything ever again.

  11. Sounds like the whole idea of taxes like death won't be as certain as they were once thought. IMHO taxes on time will disappear with the confusion of time increasing.

  12. Starting with the assumption that there are other planets with life on them, it's clear that our present scientific theories are in conflict with the fact that we can't find these aliens, communicate with them, nor sense them.

  13. This video mentions that you will not have another planet with the same year around a single star because you cannot fit more than one planet in the same orbit… well, this is NOT correct, in an an engineered solar system. There is a person doing work on how many planets you can fit around a single star in stable orbits:
    This is how the series started:
    I would prefer this approach of mega civilization as I regard planets more resilient in the long term than constructed habitats… you can leave planets alone for billions of years and they will maintain life. I would add stellar engineering to extend life of the central star, some sort of geo-engineering to reheat cores of the planets to keep tectonics going and add multiple stars in well separated orbits to the arrangement. You can turn the Oort Cloud of such a system into materials storage by moving rogue planets into it, or even doing the same with black holes.

    This channel has always talked about mega civilizations using mega structures and Dyson Swarms, I wish it also explored some other possibilities such as the one above.

  14. I think I worked out that my 1.6 gigasecond birthday is January fifth or seventh and the standard for JavaScript and most other programming languages is just a little less, midnight 1 January 1970. Considering legacy issues I have always assumed for spaceborne populations we'll use megaseconds and gigaseconds. We wouldn't get to terraseconds until about AD 33K

  15. It seems like having localized time zones based on radial distance would make the most sense. In reality your local time in relation to everyone else ia going to be based on your location in space

  16. Galatic empire governance will have to be ruled in a coalition, individual planets will have to be self governing and be self sustaining. Otherwise theres no point in colonising other planets. More efficient to stay in the same planet and use other planets for resource collection.

  17. Great video and man… What a headache. I'd say this topic is a bit like trying to untangle a box full of Christmas lights. Haha

  18. This is one of the benefits of rotating spacestead habitats, you could make the day length and year length whatever you want it to be.

  19. I don't see why day length will be very important on most planets and moons, as people living on the majority of these worlds will be living inside bunkers. Thus they could easily replicate a 24ish hour day, possibly with systems of shades and mirrors over skylights.

  20. Dear Isaac Arthur, there is much deeper gravity well that happens in the USA that slows time to nearly 0 .. it takes 2 things.
    1 Wife
    2 Walmart
    3: Clothing section, when one enters the Clothing section at Walmart, with wife, time indeed slows to 0.

  21. A good way to remove most of the arbitrariness from timekeeping is to use unitless measures (Planck units). The zero can be defined as the start of human civilization, an estimate to when humans first became capable of agriculture of at least up to sustenance farming levels. It doesn't really matter where the zero is, because you should be using relative timestamps anyways.
    Although saying MegaGigaGigaGigaGigaPlanck durations is kinda unwieldy when you're trying to count seconds.

  22. Love your vids. The imagination is really the gem of the human race.. Well, mostly. I would love to have a space ship that could go so close to the speed of light that I could watch the universe shrink to a dot and be able to go to the farthest galaxy though once you got there it would be totally different than what you see as stars would be born and die as you approach it. It still would be a nice trip. I wonder how light see's the universe. I wonder if it even has any concept of time or is outside of time as it moves through the universe. I'm not smart enough to know but would like to know just the same. I also wonder if you had a ship that could somehow reach light speed, would it turn into a mini-black hole as it reaches inif. mass? Lots of neat weirdness in the universe.

  23. 22:22 – Taxes in the relatively distant future? Government might not exist by that time, and if they still exist by then, they most probably would have moved to a different paradigm.

  24. Time is just our imaginary concept. I think that in far future there will be totally different math and physics and all these problems will be non existing. Hope Isaac will make another episode on time soon 😊

  25. I love the video content, but the odd pronunciation accent is just too distracting for me.

    This would be the first time I actually suggest a channel use a robot/computer voice to do the narration.

  26. "….or Love Coffee – the Original Life Extention Technology."
    yes. Yes. YEs. YES!

    Regarding keeping track of time. Couldnt we use Pulsars as our clock for multiple systems?

  27. Yea it’s pretty annoying talking with friends living in Europe, Asia or Australia when it’s the morning in my time zone it’s usually nighttime or very early morning for them

  28. the laws and traditions of how various groups record and compute time will evolve over many thousands of years and hundreds of civilizations. something that will seem natural to those living in that far future

  29. Issac, I'm disappointed. You barely touched on HOW we would be keeping time – atomic clocks, with improvements, etc. What about interstellar time, with quasars, black hole ejecta, pulsars, blazars, extragalactic clouds' position? Who gets to decide Milky Way Zulu Time?

  30. 128 bit Unix timestamp and computers for converting based on Lorenz transforms. Everything else is local. Problem solved.

  31. How the heck does Isaac produce these episodes? Does he simply have a massive database of cgi cosmic & hard sci-fi stock footage that he searches & edits in over the essay, or do he (or a team of vfx artists?) custom render each episode, reusing older previous clips as needed? I am very curious as to the entire production workflow, tbh. As I’m sure we all realize, this show has a production value light years above anything similar or most web series in general. I’m constantly awed not only by the depth of research & understanding communicated in each episode, but the pure aesthetic quality & attention to tone & detail. Would anyone else be interested in a meta behind-the-scenes episode? Sorry if this has all already be answered elsewhere — I’m just a bug fan of how well this show is made!

  32. It would probably be pretty dangerous to walk around in a filthy meatbody if you slowed your brain down.

    We already have more than enough coconut related fatalities.

  33. Just don't let the software guys set the local time, or it'll be based on Linux Epocs….

    localTime = AdjustForRelativity(time.time())

  34. While this is entertaining speculation for us, it will probably be hilarious (or incomprehensible) to the "people" who actually engage in interstellar colonization, assuming that happens. Space travel is a "slow" technology. It involves moving lots of matter around, using principles and technologies that are already mature or at least well-understood in principle. As an example, consider that SpaceX is only now getting the capability to develop the Shiny Silver Rocketship featured so prominently in 1930's – 1950's sci-fi, and if things work out for them, SSR's might be fairly commonplace a few decades from now. In contrast, compare how much "fast" technologies like computers and biotech (i.e. technologies that primarily manipulate information rather than mass) have changed since then, and how much they'll change in the next few decades. Or even relatively slow-moving things like cultural and social change.

    By the time we've widely settled the Solar System, the "fast" technologies will have changed "people's" lives so much that they will be as different from us as we are from trilobites. To ponder how they'll calculate "wages" and "taxes" is like an ancient Egyptian asking, "But how will you use an obelisk to mark the solstices on an O'Neill colony?" only more so by orders of magnitude.

  35. "In an era of computers it's not such a big deal…" lies. Hogwash. Balderdash. You've passed the problem onto programmers and we hate time and dates. If I had my way we'd all use Unix Time and be done with it. A day is 84.6 kiloseconds, the rate a rock spins in the void is only locally important.

  36. A great video, no matter what time it is. I feel you on trying to catch up on the reading list, mine is also continually growing at a faster rate than I can keep up with.

  37. And here I was thinking of a merchant ship that travelled between systems.
    Keeping track of time is going to be a pain in the but.

    Also, I've had shifts that were so boringly slow that I would want to slow down how much time I see so the shift moves by quickly.

  38. What a episode to wrap up such a wonderful year. Thanks for all the wonderful content Isaac and team, teaching me more than I ever could imagine before each episode.

    I wish you a Happy New Year and that 2020 be a great year for you and the team.

  39. i can solve the day differents but not the relavistic.
    all you needs is a new way of counting. like internet time.
    we all call second (or any amound of time). but forget about days and week and years.
    for some planets you just get different time per day. but we all call it the same.

    its the same reason i want to deled the time zones. lets just all pick a time. and have all the same. who cares that 12:00 is early in the morning instead of mid-day. you mast release the connection between the number and the time of day. its only just a number. for some 7:00 will be morning for other late at night. in about 2 generations it could be normal.

    relativitie might be harder to solve.
    maby we can make a clock not based on a constant but based on the entropy of the observable universe. might be difficult to put a number on that. but its the only thing that is the same anywhere. and even if it doesnt feel like it. the soon as to "clocks" come to gether they will always show the same. however it might not be the most accuract way for short timing. and time experience and the clock are now not the same thing. you second might experience more entropy than some one else his second.

    a second plan is using the comological constant and other parts of dark energy. as dark energy seems to be evenly strong everywhere.

    but removing the clock away from time is not a concept many people can understand, as it is not that usefull for everyday task.

    so the more practical solution whould be to have every star system have its own time. and than have some galaxtic time to compare it to. and in between travel it gets average, or maby slowing changed from one to the next(like overcoming jet lack).

  40. We have serious issues to address. FTL is fantasy. Works for fiction. In fact it is essential for sci fi fantasy. I have listened to every show you have done. Just when you got all the pieces aligned, you ran this horse to the ground. Seinfeld ended. Friends ended. Michael Jordan retired at the top of his game.

  41. I think this answers the Fermi paradox. Civilizations do not survive long enough to contact each other because they go bankrupt from all the time based back taxes they have to pay.

  42. So what I'm getting from this is Space Capitalism has the potential to become so much more fucked up than planet bound capitalism.

  43. Methinks the producer of this video needs to do a bit more research – humanity has been contacted numerous times during our history here on Earth. For starters, time is an illusion of our conscious creation, albeit, a persistent one. In the Greater Reality, all there is, is the Eternal Present. And that's just the 'tip of the iceberg'.

    Here's a web site with such knowledge about 'other civilizations'… it's been around since the mid 90's, and was compiled by Col. Wendell Stevens, comprising of multiple witnesses and encounters. www dot galactic dot no/linkmap dot html (insert the dots and remove the spaces) Note that not all are in English. Humanity has Never been 'alone', but we are seen as 'children' in the cosmic scheme of life, and we have much to learn – which is the primary reason that more advanced Civilizations do not contact us 'outright'. Sort of like the 'prime directive' portrayed in the 'Star Trek' tv series.

  44. Consider the issues in coordinating bitcoin blockchains with Mars……

    (Anyone think people will still use money by the time Mars is colonized? 🙂

  45. Create a time-organization that selects 1000 or so pulsars. Average the pulsars and use that as the time standard. Biological time will become irrelevant as we aren't far out from perfect regeneration anyway (100 years or so IMO).

  46. I'd expect earth standard to be used, due to evolution. Taxes paid based on local time passing. Pay based on 'active time', not while in deep freeze.

  47. Betelgeuse is entering a new phase of faintness- I'm told this is unusual. What's your take on it? It sounds like the star has done this before on multiple occasions- I think it'd be amazing to witness a safe supernova.

  48. It's 10 minutes into the video, and you haven't talked about synchronizing clocks. Having a common understanding of "when" an event occurs gets very complex in our solar system let alone over the vast distances of the galaxy or large velocities of spacecraft or potentially deep gravity Wells requiring the calculus of relativity.

    As for timekeeping, it doesn't matter what timekeeping system is used as long as everyone knows how to use it/convert to or from "universal time". Perhaps a solar-system-wide or galactic-wide solution is similar to Unix time: have everyone use a unit of time that can be locally calculated; then have something broadcast a signal stating how many units of time has passed a since some special moment of time denoting the "start" time. For galactic civilizations, perhaps groups of pulsars are the ticks of the clock, and each group needs to keep track of the number of ticks similar to how ocean voyagers in the 19th century brought clocks so they could identify their longitude. When groups communicate, perhaps the first message is syncing clocks.

  49. Time really did seem to slow down watching this,,,gotta go though,have a table booked at the last restaurant in the universe

  50. Isaac Arthur, is there a reason you don't accept Subaru telescope team's Milky way width or are you just using 100k ly as a general value – not the furthest from far point to far point ? I admit I haven't read the study but BHB stars are said to drop a lot by their data. Of course it is only one telescope doing survey (as far as I know) so due caution is in order of course.

  51. The way I handle Day, month and year spans for my scifi universe is that they have a standardized year which (I accept it, I'm lazy) comes to 365 days. The homeworld of one race would take a few hundred earth years to complete one trip around their sun. They handle days similarly, they have a standard day that is based on the daily schedule that is healthy for most races. 24 hours (strangely, most of the races discovered have many similarities.) I ignore relative time scales to avoid Scanners-izing myself trying to track all of it.

  52. Thank you Isaac and team, I'm so glad I found your channel and appreciate all the work everyone has done to get it where it is today. Thanks again for the quality entertainment and I love you all and wish you the best of futures!

  53. All those specifics about taxes and trading and timekeeping went over my head. But I think that was the point: this is all very, very, very confusing. On the other hand, this video, while being very confusing in its specifics (that was probably the point anyway), makes you think…a lot. Heck, every SFIA video does, but this video really strained your brain on how these problems could be figured out. How would these civilizations coordinate the most basic of events betweem systems? Yes, those basic events are mundane to those civilizations. But the way they have to keep time would be so mind-bogglingly astounding to us. And that is what makes it fun to think about. As the time ticks by as I'm typing this, remind yourself the Earth clock is ticking away…and we definitely don't want the Moon clock or the Mars clock ir the Neptunian clock or the Venetian clock to make it tricky to debate when we figured this exact problem out. 😀 Figure these issues out before all those clocks exist, preferably. 🙂

  54. There are no inter or interstellar civilizations? Why are there no photographs of aliens! Because there are none to be photographed! Why are the drawings or paintings of aliens always humanlike? Walking upright, head, arms, legs, eyes, ears, noses, mouth? Just different skin, sometimes big slanted eyes! It's because people make it up as they go! The "Grey's" are evil and can climb walls like spiders and live in darkness! Why aren't their eyes really big? The "reptilians" look like lizards but they walk upright and have hands and feet and speak like humans! Then the "whites" who look exactly like humans but have white hair, very pale skin and big blue eyes! They are said to be evil as well! Then there is the little white skinny, long necked "ET" type, with long skinny arms and legs! Two were purportedly found after a crash and after a few days died, when they cut them open their insides were gel!!?? It's utterly ridiculous! Even if there were aliens and they attempted to contact us the government would shoot first and ask questions later! It malarkey!

  55. As much as I love gaining knowledge at the feet (video monitor?) of Isaac Arthur, I do have a few simple hopes.
    I hope that everything we've learned so far turns out to be just that tiny fraction of the puzzle that the great thinkers of the past had to work with. I hope we do unlock the ultimate secrets of the universe. I hope we do get there.
    And most of all, I hope that we have a long, long time to search for those answers. the endless reaches of space time

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