Zompist Bboard Again

In this thread, I will expand a bit on the idea for a conworld I asked for opinions on a few days ago...

So this is a science-fiction setting, vast enough to contain many other settings, not all of them modern in tech level at least.
I tried to make it reasonably hard SF. Meaning there's a lot of invention, and quite a few curtains behind which stand men you don't want to pay attention to... But I've tried to stick to science whenever possible.
There is FTL in that setting, though I've kept it as plausible-sounding as physics currently allows.

A good bit of the science and quite a few concepts are cribbed off Winchell Chung's Atomic Rockets website.
If you're planning at having so much as a satellite in orbit for your conworld, I suggest you look at it if you haven't already.

A short introduction

You are a citizen of the Galactic Empire. It doesn't matter that nobody on Earth (except for me, and you, now!) is aware of the fact doesn't change that fact.

The undisputed capital of the Empire is Yttes a, shall we say, customizedmoon boasting a population of around 7 billion.

The Empire claims ultimate jurisdiction over any and all hominids in the Galaxy. It is generally able to back up this claim. The Yttesians know about us. One reason we don't know about them is that they respect our unique cultures and don't want to damage them. Another is that they'd have to take over as soon as we found out, and we'd be more trouble than we're worth.

More on all this later; for now we need to talk a bit about wormhole. (No equations below, but be warned that it can be a bit of a mindscrew).

Wormholes.

We all know the drill. Space is big. in fact getting anywhere even remotely interesting in our solar system is incredibly difficult. Interstellar travel is right out.

There is, however, a solution that a reasonably advanced civilization can figure out, and that is wormhole.
Microscopic wormhole can be manufactured through the careful application of very high energies. By microscopic, I mean 'about the size of an elementary particle'. Both ends are, at best, a few Planck lenght apart.
Not very useful at this stage.

Now, a tidbit on wormhole engineering. A wormhole is a shortcut in space and time leading from one event to another without crossing the intermediate distance. (Keep in mind the 'time' part. It will prove important later.)
At the same time, wormholes are regular, normal, physical objects, with charge, mass, and momentum.
All three are conserved locally. If you send ten grams through a wormhole end, that wormhole end will gain ten grams. And its opposite number will lose ten grams.
If you send a positively charged particle through a wormhole, it will acquire a corresponding negative charge.
Likewise, if you send a high momentum particle, this will move the wormhole ends.

Let's go back to our tiny wormhole end. What I've just said means we can keep put a charge on both ends, keep one end stationery, and accelerate the other at relativistic speeds by a particle accelerator.

Let's keep one end at home (which happens to be in Yttes) and accelerate the other end very close to light-speed and shoot it towards the Massotis system (about 100 ly away).
The trip takes, of course a bit more than 100ly from Yttes perspective. But! Do you remember relativistic time dilation? From the point of view of the travelling wormhole end, it takes two months.
So, shoot your wormhole, look through it after two months, and you'll see the Massotis system.

As it happens you've sent your wormhole directly through the atmosphere of a convenient gas giant. Gas shoots through your end; you send equal mass the other way (otherwise mass drops to zero and your wormhole drops out of existence!) in such a way that you eventually steer the wormhole away from the gas giant. Put it in orbit where you like.
Now you can step through your wormhole and find yourself in the Massotis system.

Due to relativistic time dilation, though, the wormhole sends you 100 light-years away and two months short of 100 years in the future.
Of course, going back the other way, from Massotis to Yttes sends you back 100 years.

OK, now for a bit of mindscrewing.

We send a wormhole from Yttes to the Solar system, about 120 light years away.
Now send a wormhole from Massotis to the Solar sytem (a distance of 150 light years, give or take).

OK. Now start from Sol. Get to Massotis. You've gone back in time 150 years. Now get from Massotis to Yttes. You go back in time 100 years.
Now, go back to Sol from Yttes. You go forward in time 120 light years.

Now, let's take a look at your trip through space-time:
Place | Date
Sol | 0
Mass | -150
Yttes | -250
Sol | -130

Yep. You end in the same place, 120 years before you started.

There's no such thing as time travel in our universe, though. In fact what happens in fact is that light and/or particles would loop around our three wormholes until one of them collapses. (And by collapse I mean turn into a black hole or release a starship's worth of energy or both).

In practice this means that a wormhole network is an acyclic graph (no loops allowed). A tree, if you like. Meaning that there's no going around whoever connects the strategic bits of a tree; you can't set up alternate routes and whoever controls the tree fully intends to keep it that way.

And here's our Galactic Empire. As it happens, just like all roads lead to Rome, all wormholes lead to Yttes.

The Very Old Ones
There's the Galactic Empire now, of course, but what was there before? There had been intelligent life before the first primordial cell divided in Earth's oceans. Some of these sentient species, of course, figured out wormholes.

We call one of these the Gardeners, or the Very Old Ones. Several hundreds of Earthlike planet were once connected by a wormhole network. We don't know exactly when it was build, but that was at least one billion years ago.

It's possible the wormhole network still exists, but if it does, it's probably inactive, in a way that's beyond our, or the Yttesians' understanding of physics. Otherwise the current network couldn't have been built.

In any case it was last active about 60,000-40,000 years ago.

But how do we know this?

That's simple enough. On several hundred planets, much of the native biosphere is related to Earth life. They use DNA, the same set of amino-acid, and prefer the same range of temperature. You get weirder stuff around deep sea vents.
Some of these have species that are recognizable birds, reptiles or mammals.
And -- to the considerable surprise of early explorers -- many of these planets are home to hominids, and often enough of the particular homo sapiens species.

And, for all of these species, behavioral modernity came about 60,000-40,000 years ago.

There are a lot of questions about the Very Old Ones / Gardeners, and few definite answers. A few ideas, though:

1) Why did the Gardeners do any of that?
The Gardeners were building, y'know, garden worlds. Let me expand a bit on this.
On a cosmic scale, post-scarcity, in the sense of obtaining energy, materials, and producing manufactured goods in large quantities is really not that hard or far away. Yttes is kind of quite there already, and it's millions - no, billions - of years behind a really advanced society.
At a certain point, what is most valuable? New information, and the truly unique. You can't beat biospheres for unique or new information.
What they were doing was, in fact, spreading a biosphere to other less, interesting planets. Possibly they combined several early biospheres together.
There's some hint that they had specific tastes and ideas on what they were doing. On many -- but not all worlds -- mass extinction seems to have occured right on schedule. (All except Bug planets had an Ordovician-Silurian extinction. A third had an equivalent of the KT extinction.)
Bugs and Bug relative are found on quite a few planets. So are humans and their relatives. Possibly the same is true of other species.
2) Why did they keep at it for a billion years?
Many think the Very Old Ones operate at a different speed from us, and see events on the scale of geological epochs. They might be very slow beings drifting in interstellar space.
Others think they went off to their own pocket dimension with time dilation with respect to us. Others yet think they were from a different universe in the first place.
Another interesting possibility is that they didn't. That, really, several species operated the same network, or built a similar one. The Gardeners that in some way encouraged modern behavior 60,000-40,000 years ago in several hominid species might well have been an entirely different species from those that played around with algae a billion years ago.
3) Where are they?
Nobody's ever seen a Gardener. Aside from foot/tentacle/appendage-prints of the very old, eldritch type (subtype: squamous, eldritch and rugose) who may or may not have been our guys. Maybe they're still around. Maybe they're made of dark matter. Maybe they'll show up in a million years to see what we're up to.
There are of course enough abduction stories and conspiracy theories in the Empire to keep you entertained for a whole lifetime.

Some practical notes on wormholes.

As far as we can see, the Gardener wormhole were (at least at some point) on planetary surfaces. We can even make guesses at where they were. (It seems for instance, that there was a route from Earth's South America to Massotis' northern continent of Sarugond.)

There's nothing really preventing you from placing a wormhole on a planetary surface, except that it's an engineering nightmare.
First, wormhole ends are denser than regular matter. Which means they tend to sink. Have you ever tried to recover a wormhole from the mantle? Second, remember what I said about the mass explosion/black hole failure mode? Third, they move around every time you get through them. Third, you need to have mass lying around to feed the 'hole regularly. (Remember, wormhole ends decrease in mass everytime something arrives.)

For that reason, the Yttesian puts them close, or even within convenient asteroids. They prefer doing things in orbit anyway; they don't like planetary surfaces.

The one wormhole end in the solar system is inside a near-Earth asteroid. They live to move these around a bit to place them in a more convenient orbit; but in our case they didn't. (They found in the mid-20th century: we would have noticed an asteroid changing orbit.)

It takes about 4 to 20 days to get to the Sol wormhole depending on the season, and the ship you're using. Generally, interstellar travel takes days, weeks or even months. In practice they build wormholes between systems that are quite close together (to steer your wormhole, you need to have measured the orbit of the major planets in your target system with some precision), with some travel time between.

If that sounds slow, remember that it still means that a small civil passenger craft has the power output of a nuclear power plant. (Han Solo's a nice man, but him being able to do Chernobyl levels of damage is more than enough).

How is Yttes pronounced? I'm mentally waffling between [iːts] and ['ɪt.tiːz] presently.

I also like the idea of multiple worlds being seeded with the same sort of life. Not much else to add, other than that I had no idea wormholes were a sort of stationery. What does one write on or with them? that I take it some form of fiction or language-building may also be forthcoming?

That way I'll interesting. Are you going to write a novel or short story? What kind of creatures are the Yttesians? What is the gravity on Yttes?

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 5:30 pm How is Yttes pronounced? I'm mentally waffling between [iːts] and ['ɪt.tiːz] presently.

I'm like it's French! So [yts] or something?

Interesting stuff. Though I don't think you explained the potato bit?

A quibble on the wormholes. I think you're not taking account of general relativity? I get that from the wormhole's perspective, it took 2 months to make the trip, at near-lightspeed. But then it decelerates to take a position at rest in the target star system. Deceleration undoes all the neat relativistic effects. So I don't think you'd have the time effects, cool as those would be. (You can add them back in as space magic if it's important to you...)

On biology, I hope you'll avoid Larry Niven's mistake, which is to have the whimsical god-aliens encode humanoid structure into bacterial DNA, IIRC, so that humanoids develop all over the galaxy. That was, to put as nicely as possible, something you could maybe get away with in the 1970s. DNA mutates randomly all the time, so any encoded info that's not actively used by current organisms would soon by corrupted into nonsense. (The genetic code is "purposely" redundant in that changes to one base pair out of the three that code an amino acid usually select the same amino acid— so the system is "designed" to account for a high-mutation environment. If core genes are mutated, the organism usually dies.)

If you're getting actual Homo sapiens on multiple planets, it can only be that the Gardeners are personally interfering, moving flora and fauna around.

How often do they intervene? If it's about every 50,000 years, it would be hard to tell their interference apart from normal evolution. That is, an introduced species would be very similar to what's there before, and scientists would take it as a mutation.

If it's more like 5 million years, I'd expect that this would be visible in the genome. You'd get new species appearing that have too many mutations at once. You could probably identify and trace the interventions with science of about our level.

As I said earlier, I love this idea! As per usual, I have questions:

Ares Land wrote: ↑Thu Jan 28, 2021 12:04 pm The undisputed capital of the Empire is Yttes a, shall we say, customizedmoon boasting a population of around 7 billion.

The Empire claims ultimate jurisdiction over any and all hominids in the Galaxy. It is generally able to back up this claim. The Yttesians know about us. One reason we don't know about them is that they respect our unique cultures and don't want to damage them. Another is that they'd have to take over as soon as we found out, and we'd be more trouble than we're worth.

Quick question: are the Yttesians humanoid or not?

(also, I prefer Yttrians to Yttesians, not that it matters)

All three are conserved locally. If you send ten grams through a wormhole end, that wormhole end will gain ten grams. And its opposite number will lose ten grams.

But what does ‘locally’ mean? From a topological perspective, ‘locally’ would include the stuff on the other end of the wormhole. So just sending it through without any change in the wormhole properties still conserves quantities locally.

OK, now for a bit of mindscrewing.

We send a wormhole from Yttes to the Solar system, about 120 light years away.
Now send a wormhole from Massotis to the Solar sytem (a distance of 150 light years, give or take).

OK. Now start from Sol. Get to Massotis. You've gone back in time 150 years. Now get from Massotis to Yttes. You go back in time 100 years.
Now, go back to Sol from Yttes. You go forward in time 120 light years.

Now, let's take a look at your trip through space-time:
Place | Date
Sol | 0
Mass | -150
Yttes | -250
Sol | -130

Yep. You end in the same place, 120 years before you started.

There's no such thing as time travel in our universe, though. In fact what happens in fact is that light and/or particles would loop around our three wormholes until one of them collapses. (And by collapse I mean turn into a black hole or release a starship's worth of energy or both).

I don’t see how this would work. Not the time travel, that is — that’s quite straightforward — but how the ‘looping’ would work.

So, let’s take an example. Start in, say, Spain, in year 0. Create a wormhole and travel to Yttes (year=120). Create a second wormhole and travel to Massotis (year=220). Create a third wormhole and travel to New Zealand to finish the loop (year=370).

Now wait a few hundred years, till year=1000 (so that you don’t accidentally travel to a time before you made the wormholes). Now, starting from NZ, travel to Massotis (year=1000-150=950). Starting from Massotis, travel to Yttes (year=950-100=850). And starting from Massotis, travel to Spain — year=850-130=720. Spain, however, is on the opposite side of the earth to NZ, where you started. So how does the matter magically travel to NZ to ‘loop around’ again? (And this ignores the fact that, eventually, you’ll end up travelling to a time before the wormholes were created, so you can’t loop around again.)

That's simple enough. On several hundred planets, much of the native biosphere is related to Earth life. They use DNA, the same set of amino-acid, and prefer the same range of temperature. You get weirder stuff around deep sea vents.
Some of these have species that are recognizable birds, reptiles or mammals.
And -- to the considerable surprise of early explorers -- many of these planets are home to hominids, and often enough of the particular homo sapiens species.

Nitpick: birds are reptiles, so recognisable birds implies recognisable reptiles (and also recognisable dinosaurs as well).

There's some hint that they had specific tastes and ideas on what they were doing. On many -- but not all worlds -- mass extinction seems to have occured right on schedule. (All except Bug planets had an Ordovician-Silurian extinction. A third had an equivalent of the KT extinction.)
Bugs and Bug relative are found on quite a few planets. So are humans and their relatives. Possibly the same is true of other species.

Huh, so the Bugs are part of this as well? Neat.

As far as we can see, the Gardener wormhole were (at least at some point) on planetary surfaces. We can even make guesses at where they were. (It seems for instance, that there was a route from Earth's South America to Massotis' northern continent of Sarugond.)

One idea I’ve been thinking about is that wormholes might have been what kickstarted civilisation, since they allow higher population density. So, for instance, there might have been ones in Sumeria and China. (I personally would be unsurprised to discover one between Mesoamerica and the Simbri-speaking area. There’s more than enough caves to hide one in Mesoamerica, at least.)

There's nothing really preventing you from placing a wormhole on a planetary surface, except that it's an engineering nightmare.
First, wormhole ends are denser than regular matter. Which means they tend to sink. Have you ever tried to recover a wormhole from the mantle?

I’m not sure this follows. For instance, I happen to have a jar of iridium sponge (long story), which I keep on a wooden shelf. Said iridium shows no signs yet of sinking through the shelf, despite density considerations. If you want the wormhole to actually sink through the crust, you’d have to use, say, neutron star densities — at which point, I suggest, you would have greater problems than your wormhole ending up in the mantle.

In general, I feel that there’s a persistent ambiguity here as to exactly how wormholes work. Are they actual, physical objects, or are they part of the topology of the universe? If the former, that makes them easy to transport — but then how does stuff travel through them? If you touch one with your finger, does the finger get transported to the other side, or does the substance of the wormhole prevent my finger from occupying the same space as the wormhole? If I put one on a table, the molecules in the table aren’t suddenly going to jump up into the wormhole (which would be thermodynamically improbable) — but will just touching the wormhole be enough for these molecules to be transported to the other side? (I hope not, since that really would make it impossible to have a planetary wormhole without it falling through to the mantle.) On the other hand, if a wormhole is simply topology, that makes these questions trivial to answer — but then how exactly does one transport a piece of locally non-Euclidean topology?

zompist wrote: ↑Thu Jan 28, 2021 6:07 pm How often do they intervene? If it's about every 50,000 years, it would be hard to tell their interference apart from normal evolution. That is, an introduced species would be very similar to what's there before, and scientists would take it as a mutation.

When I said I had been thinking about wormholes, this was pretty much exactly what I was thinking. In particular, you could get there by changing the nature of the wormholes, by making them easy to make, but extremely hard to maintain (over geological timescales at least), so they crumble to dust after a couple of thousand years and you have to keep on coming back to make new ones.

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pm

There's some hint that they had specific tastes and ideas on what they were doing. On many -- but not all worlds -- mass extinction seems to have occured right on schedule. (All except Bug planets had an Ordovician-Silurian extinction. A third had an equivalent of the KT extinction.)
Bugs and Bug relative are found on quite a few planets. So are humans and their relatives. Possibly the same is true of other species.

Huh, so the Bugs are part of this as well? Neat.

Being actually a fairly long lurker, I think I know what this is, but I'm not sure, and I can't find a thread about it...

Edit: This?

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pm Lots of other things

Now all this is asked, I want to know the answers, too.

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 5:30 pm How is Yttes pronounced? I'm mentally waffling between [iːts] and ['ɪt.tiːz] presently.

I also like the idea of multiple worlds being seeded with the same sort of life. Not much else to add, other than that I had no idea wormholes were a sort of stationery. What does one write on or with them? that I take it some form of fiction or language-building may also be forthcoming?

Oh, I forgot to give the pronunciation. It's [ɯt.tʰɛs]
There will indeed be some language building, and hopefully fiction.

Qwynegold wrote: ↑Thu Jan 28, 2021 5:35 pm That way I'll interesting. Are you going to write a novel or short story? What kind of creatures are the Yttesians? What is the gravity on Yttes?

Yep, I'd like to.

The Yttesians are hominids. Specifically they're a separate species in genus Homo. There's no really striking differences: you have to know what to look for to tell them apart from Homo sapiens.
Yttes is a small moon - in the same ballpark as Phobos or Deimos, so gravity is negligible -- but artificial gravity is available.

zompist wrote: ↑Thu Jan 28, 2021 6:07 pm Interesting stuff. Though I don't think you explained the potato bit?

Ah, yeah. I meant to explain that but the post turned out longer than expected. Yttes is nicknamed 'the Potato' or 'the Big Potato'. It's not a very imaginative nickname: it just looks like a potato.

I will be posting more about Yttes and the Yttesians soon.
(Yttrians? Yttesi? Yttesites? I don't know yet how demonyms work in their language.)

A quibble on the wormholes. I think you're not taking account of general relativity? I get that from the wormhole's perspective, it took 2 months to make the trip, at near-lightspeed. But then it decelerates to take a position at rest in the target star system. Deceleration undoes all the neat relativistic effects. So I don't think you'd have the time effects, cool as those would be. (You can add them back in as space magic if it's important to you...)

Sorry, I'm not sure I understand your quibble. Deceleration doesn't undo the time difference; indeed it is true that there are no more (*) relativistic effect once the wormhole is at rest. But the trip still took only 2 months from the wormhole's perspective.
You might be thinking of how, when considering a starship, the relativistic effects aren't as big as you'd expect since you need to take quite some time decelerating.
But at this stage the wormhole is still the size of a proton, and not much more massive. The deceleration can be done very quickly and with very high g's.

(*)In fact there still are because the wormhole ends aren't going to have the same orbital speed and will be subject to different gravity. But let's ignore that for now.

On biology, I hope you'll avoid Larry Niven's mistake, which is to have the whimsical god-aliens encode humanoid structure into bacterial DNA, IIRC, so that humanoids develop all over the galaxy. That was, to put as nicely as possible, something you could maybe get away with in the 1970s. DNA mutates randomly all the time, so any encoded info that's not actively used by current organisms would soon by corrupted into nonsense. (The genetic code is "purposely" redundant in that changes to one base pair out of the three that code an amino acid usually select the same amino acid— so the system is "designed" to account for a high-mutation environment. If core genes are mutated, the organism usually dies.)

No, nothing like that is planned.
Evolution proceeded as it normally does. The one difference is that wormholes allowed species to get from one planet to another, rather like going from one continent to another through a narrow isthmus.
It's (purposely) not very clear what form Gardener intervention took. For instance the KT extinction occured on some, but not all planets. Presumably they saw something interesting in mammals?
It also seems they encouraged hominid spreading on multiple planets. Perhaps this was done to avoid extinction: hominids seem to be vulnerable. (The lack of diversity in our own species is telling, and implies we went close to extinction ourselves.)
Some external factor also contributed to the rise of behavioral modernity.

They had no preference for humanoids, but it seems they did like sentient species and encouraged their development. Bugs got the same treatment hominids did, as did other sentient species I haven't invented yet

How often do they intervene?

Very rarely. How often do species cross the wormholes, though? I think your figure of 50,000 years makes sense. (At some point oddities do show up in the fossil record, but our own paleontology hasn't reached that stage yet.)

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pmBut what does ‘locally’ mean? From a topological perspective, ‘locally’ would include the stuff on the other end of the wormhole. So just sending it through without any change in the wormhole properties still conserves quantities locally.

It doesn't include the other end. Basically, if something goes through a wormhole, it's just as if it disappeared into a black hole, or went to another universe.

Now wait a few hundred years, till year=1000 (so that you don’t accidentally travel to a time before you made the wormholes). Now, starting from NZ, travel to Massotis (year=1000-150=950). Starting from Massotis, travel to Yttes (year=950-100=850). And starting from Massotis, travel to Spain — year=850-130=720. Spain, however, is on the opposite side of the earth to NZ, where you started. So how does the matter magically travel to NZ to ‘loop around’ again?

It's not just normal matter, but also radiation, neutrinos, etc. For instance, neutrinos can get from Spain to NZ... Even virtual particles arising from quantum fluctuation loop around and get amplified until one of the wormholes in the loop gets destroyed.

In general, I feel that there’s a persistent ambiguity here as to exactly how wormholes work. Are they actual, physical objects, or are they part of the topology of the universe? If the former, that makes them easy to transport — but then how does stuff travel through them? If you touch one with your finger, does the finger get transported to the other side, or does the substance of the wormhole prevent my finger from occupying the same space as the wormhole? If I put one on a table, the molecules in the table aren’t suddenly going to jump up into the wormhole (which would be thermodynamically improbable) — but will just touching the wormhole be enough for these molecules to be transported to the other side? (I hope not, since that really would make it impossible to have a planetary wormhole without it falling through to the mantle.) On the other hand, if a wormhole is simply topology, that makes these questions trivial to answer — but then how exactly does one transport a piece of locally non-Euclidean topology?

They are really both. Or more precisely, the wormhole itself is part of space-time topology, but the wormhole ends are physical objects.
Just like black holes, which are both physical objects with charge, mass and momentum and part of the topology.
Touching the wormhole is enough to get you on the other side. (Well, not exactly. You get into the 'tunnel' connecting both ends.)
You could still have in theory a planetary wormhole by charging it and using electromagnetic forces to keep it in place.
In practice, nobody masters the engineering required to do that. Presumably the Gardeners did.

(On wormholes, I should add that all of this is actual physics, ie. what general relativity and quantum physics predict for actual wormholes. The caveat being that all of this is way beyond my understanding of physics. So there are possibly mistakes, and I can't explain this as well as a real physicist would.)

When I said I had been thinking about wormholes, this was pretty much exactly what I was thinking. In particular, you could get there by changing the nature of the wormholes, by making them easy to make, but extremely hard to maintain (over geological timescales at least), so they crumble to dust after a couple of thousand years and you have to keep on coming back to make new ones.

This is indeed what happens. (You need to keep the mass of both ends more or less balanced, keep the wormholes in place despite trips through them adding momentum, prevent them for sinking inside planets, avoid accidentally creating a time loop -- there are tiny relativistic effects that really add up over time. All of this requires active maintenance.)

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 8:50 pm

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pm Huh, so the Bugs are part of this as well? Neat.

Being actually a fairly long lurker, I think I know what this is, but I'm not sure, and I can't find a thread about it...

Edit: This?

Yes, those very Bugs.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am Yttes is a small moon - in the same ballpark as Phobos or Deimos, so gravity is negligible -- but artificial gravity is available.

Phobos is just 11 km in diameter... roughly the size of Paris. That seems very small for a galactic hub, though not for a capital.

Sorry, I'm not sure I understand your quibble.

I think there's one error. Looking at your description again:

The trip takes, of course a bit more than 100ly from Yttes perspective. But! Do you remember relativistic time dilation? From the point of view of the travelling wormhole end, it takes two months.
So, shoot your wormhole, look through it after two months, and you'll see the Massotis system.

I think the last line is physically impossible. You launch the wormhole end in Year 0. By your own account, it arrives in Massotis in around 100.

You're saying that you can look through in year 0 + 1/6 and see Massotis. But that's not possible: the wormhole end didn't arrive there yet. (And from its own perspective, it's not 2 months from Yttes, but about 2.5 hours.)

I agree that in "wormhole time", the trip takes 2 months, but you're changing reference frames pretty freely here and those are tricky. My guess would be that at year 0 + 1/6, if you jump through the wormhole, you end up an instant later in space two light-months from Yttes. Then you're dead because the thing is still moving at relativistic speeds and you're not, but if you could get in again, you'd end up back at Yttes at about the same time you left.

Photons are just a special case of falling in. When the wormhole end is at that same point, 2 light-months out, photons can fall into it... let's say, photons from Massotis. If they're caught back in Yttes, they'd be 2 months newer than photons that arrived the normal way. So as the wormhole end moves, the view through it moves 'through the future'.

In 100, the wormhole arrives, we stabilize it in orbit or whatever, and now you can jump on through. At this point, if I understand things right, it's like a Narnia portal. You look through it and you see Mattotis "now" (in 100), whereas if you look through a normal telescope you see it 100 years ago (in 0).

I don't understand wormholes much, so maybe I've got things wrong.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 5:30 pm How is Yttes pronounced? I'm mentally waffling between [iːts] and ['ɪt.tiːz] presently.

I also like the idea of multiple worlds being seeded with the same sort of life. Not much else to add, other than that I had no idea wormholes were a sort of stationery. What does one write on or with them? that I take it some form of fiction or language-building may also be forthcoming?

Oh, I forgot to give the pronunciation. It's [ɯt.tʰɛs]

Aww, now I can't make a pun about how one Yttes the Potato.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am There will indeed be some language building, and hopefully fiction.

Both are nice things.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

Qwynegold wrote: ↑Thu Jan 28, 2021 5:35 pm That way I'll interesting. Are you going to write a novel or short story? What kind of creatures are the Yttesians? What is the gravity on Yttes?

Yep, I'd like to.

The Yttesians are hominids. Specifically they're a separate species in genus Homo. There's no really striking differences: you have to know what to look for to tell them apart from Homo sapiens.
Yttes is a small moon - in the same ballpark as Phobos or Deimos, so gravity is negligible -- but artificial gravity is available.

I like the justification for this so far.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

zompist wrote: ↑Thu Jan 28, 2021 6:07 pm Interesting stuff. Though I don't think you explained the potato bit?

Ah, yeah. I meant to explain that but the post turned out longer than expected. Yttes is nicknamed 'the Potato' or 'the Big Potato'. It's not a very imaginative nickname: it just looks like a potato.

I will be posting more about Yttes and the Yttesians soon.
(Yttrians? Yttesi? Yttesites? I don't know yet how demonyms work in their language.)

I think Yttes as both the place name and the people would be good.

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

On biology, I hope you'll avoid Larry Niven's mistake, which is to have the whimsical god-aliens encode humanoid structure into bacterial DNA, IIRC, so that humanoids develop all over the galaxy. That was, to put as nicely as possible, something you could maybe get away with in the 1970s. DNA mutates randomly all the time, so any encoded info that's not actively used by current organisms would soon by corrupted into nonsense. (The genetic code is "purposely" redundant in that changes to one base pair out of the three that code an amino acid usually select the same amino acid— so the system is "designed" to account for a high-mutation environment. If core genes are mutated, the organism usually dies.)

No, nothing like that is planned.
Evolution proceeded as it normally does. The one difference is that wormholes allowed species to get from one planet to another, rather like going from one continent to another through a narrow isthmus.
It's (purposely) not very clear what form Gardener intervention took. For instance the KT extinction occured on some, but not all planets. Presumably they saw something interesting in mammals?
It also seems they encouraged hominid spreading on multiple planets. Perhaps this was done to avoid extinction: hominids seem to be vulnerable. (The lack of diversity in our own species is telling, and implies we went close to extinction ourselves.)
Some external factor also contributed to the rise of behavioral modernity.

They had no preference for humanoids, but it seems they did like sentient species and encouraged their development. Bugs got the same treatment hominids did, as did other sentient species I haven't invented yet

So no direct engineering going on?

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 8:50 pm

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pm Huh, so the Bugs are part of this as well? Neat.

Being actually a fairly long lurker, I think I know what this is, but I'm not sure, and I can't find a thread about it...

Edit: This?

Yes, those very Bugs.

Will we be getting a war with them?

zompist wrote: ↑Fri Jan 29, 2021 5:21 am I think the last line is physically impossible. You launch the wormhole end in Year 0. By your own account, it arrives in Massotis in around 100.

You're saying that you can look through in year 0 + 1/6 and see Massotis. But that's not possible: the wormhole end didn't arrive there yet. (And from its own perspective, it's not 2 months from Yttes, but about 2.5 hours.)

I agree that in "wormhole time", the trip takes 2 months, but you're changing reference frames pretty freely here and those are tricky. My guess would be that at year 0 + 1/6, if you jump through the wormhole, you end up an instant later in space two light-months from Yttes. Then you're dead because the thing is still moving at relativistic speeds and you're not, but if you could get in again, you'd end up back at Yttes at about the same time you left.

Photons are just a special case of falling in. When the wormhole end is at that same point, 2 light-months out, photons can fall into it... let's say, photons from Massotis. If they're caught back in Yttes, they'd be 2 months newer than photons that arrived the normal way. So as the wormhole end moves, the view through it moves 'through the future'.

In 100, the wormhole arrives, we stabilize it in orbit or whatever, and now you can jump on through. At this point, if I understand things right, it's like a Narnia portal. You look through it and you see Mattotis "now" (in 100), whereas if you look through a normal telescope you see it 100 years ago (in 0).

I don't understand wormholes much, so maybe I've got things wrong.

The problem here is, I know wormholes would work that way because Kip Thorne say they do, but I can't explain why. I don't really understand it.
(A preview of Black holes and time warps where he mentions the temporal paradox consequences: https://archive.org/details/blackholest ... 0/mode/2up)
And here's where I ripped the whole process from: https://www.npl.washington.edu/AV/altvw162.html

At some point general relativity is a painful reminder of why I'm not a Nobel Prize in Physics...

I think (but I'm not sure) that jumping through the wormhole really changes your reference frame. Otherwise, this would be treating the Yttes reference frame as somewhat special. (Actually both Yttes and the travelling wormhole are stationary from their own reference frame; and from the wormhole Yttes is moving at 99.99%c. At this stage I need to reach for the aspirin.)

Rounin Ryuuji wrote: ↑Fri Jan 29, 2021 6:32 am So no direct engineering going on?

No. The Gardeners found value in what evolution and chance spontaneously came up with; implanting genes for things they already knew about wouldn't have been as interesting.
The most they did was alter the environmental conditions.

Rounin Ryuuji wrote: ↑Thu Jan 28, 2021 8:50 pm Will we be getting a war with them?

I'd love to see the 'Bug War' trope done right, so that might happen.

What would happen is that Bug planets are very hospitable to humans, except for, you know, the natives trying to kill you. So they'd be prime real estate, for Earth humans or people with a comparable level of development.
On the other hand, the Yttes (Yttesicans?) would see Bug civilization as valuable in itself but would have no need for planetary real estate.
(Of course you'd have Earthpeople defending the Bugs and Yttesers who can't stand the damn beasts.)

Among Bugs, there'd be some willing to make an alliance and share the planet, as long as the humans get rid of their rivals.
So an actual Bug War would see humans and Bugs fighting alongside in both camps.

Seeing if Space Marine Johnnie Rico can figure out he's fighting on the wrong side would make for an interesting story.

[Note: I wrote all of the below stuff before I saw your link to that Cramer article. However, I found that article somewhat unhelpful in resolving my complaints about this particular wormhole system, so I’m leaving this post as is in the hope that someone can help me understand what I’m getting wrong in my reasoning.]

Ares Land wrote: ↑Fri Jan 29, 2021 3:33 am

bradrn wrote: ↑Thu Jan 28, 2021 7:10 pmBut what does ‘locally’ mean? From a topological perspective, ‘locally’ would include the stuff on the other end of the wormhole. So just sending it through without any change in the wormhole properties still conserves quantities locally.

It doesn't include the other end. Basically, if something goes through a wormhole, it's just as if it disappeared into a black hole, or went to another universe.

But stuff from the other side can come back through, no? So it’s more like a shortcut through spacetime than a black hole (the defining feature of which is that nothing can exit it). So I still see no reason why the neighbourhood of a point near a wormhole shouldn’t include its other side. (I’m using ‘neighbourhood/local’ in the topological sense, in case it isn’t clear.)

Now wait a few hundred years, till year=1000 (so that you don’t accidentally travel to a time before you made the wormholes). Now, starting from NZ, travel to Massotis (year=1000-150=950). Starting from Massotis, travel to Yttes (year=950-100=850). And starting from Massotis, travel to Spain — year=850-130=720. Spain, however, is on the opposite side of the earth to NZ, where you started. So how does the matter magically travel to NZ to ‘loop around’ again?

It's not just normal matter, but also radiation, neutrinos, etc. For instance, neutrinos can get from Spain to NZ... Even virtual particles arising from quantum fluctuation loop around and get amplified until one of the wormholes in the loop gets destroyed.

Sorry, I still don’t quite understand how this work. To illustrate my current difficulty, let’s say I arrange my three wormholes in such a way that each endpoint isn’t in line with the next, so a particle going out the one wormhole will miss the entrance of the next one. Clearly, in such a situation, there will be very few particles which go through even two wormholes at a time, let alone loop around and around for several iterations. And even if, say, 99% of the particles going through the wormhole end up deflected into the next one, you’ll still get a damping effect: 100% of particles go through the first wormhole, 98% complete one full loop, 95% complete two loops, 92% complete three loops, 90% complete four loops, etc… The only way you can get the ‘amplification’ effect you describe is if energy is created at each step, which of course is imposible.

(As for virtual particles, I’m not sure they have any effect whatsoever; see e.g. here for a good introduction to what they are. I know you can use them to explain Hawking radiation, but that only works because black holes have an event horizon, unlike your wormholes.)

In general, I feel that there’s a persistent ambiguity here as to exactly how wormholes work. Are they actual, physical objects, or are they part of the topology of the universe? If the former, that makes them easy to transport — but then how does stuff travel through them? If you touch one with your finger, does the finger get transported to the other side, or does the substance of the wormhole prevent my finger from occupying the same space as the wormhole? If I put one on a table, the molecules in the table aren’t suddenly going to jump up into the wormhole (which would be thermodynamically improbable) — but will just touching the wormhole be enough for these molecules to be transported to the other side? (I hope not, since that really would make it impossible to have a planetary wormhole without it falling through to the mantle.) On the other hand, if a wormhole is simply topology, that makes these questions trivial to answer — but then how exactly does one transport a piece of locally non-Euclidean topology?

They are really both. Or more precisely, the wormhole itself is part of space-time topology, but the wormhole ends are physical objects.
Just like black holes, which are both physical objects with charge, mass and momentum and part of the topology.
Touching the wormhole is enough to get you on the other side. (Well, not exactly. You get into the 'tunnel' connecting both ends.)
You could still have in theory a planetary wormhole by charging it and using electromagnetic forces to keep it in place.
In practice, nobody masters the engineering required to do that. Presumably the Gardeners did.

I’m not quite sure it’s correct to describe a black hole as a ‘physical object’. A black hole is simply an infinitely dense singularity; we say it’s surrounded by an ‘event horizon’, and that is what an outside observer will see, but that’s simply a term meaning ‘a surface from inside which light cannot escape’. If you’re falling into a black hole, you won’t necessarily notice that you’ve fallen through the event horizon — it’s just an area of space, not a physical object. The mass, charge and angular momentum of the black hole are associated with the singularity of the wormhole, rather than the whole black hole being a single solid object described by those properties.

I see wormholes as being quite similar to this. As I see it, a wormhole isn’t a concrete object: it’s a region of space where, if you move through it, you’ll find yourself in a different area of space rather than the area behind the wormhole. As such, it acts just like any other region of space — if I wave my arm through one, I should find my hand on Massotis (say), my arm in the middle of the wormhole, and my body on Yttes. If you place one on a planet, it should just sit there boringly, as part of the local topology of space-time around that area. I can’t see any way to give mass to one end, for instance — you can add massive objects to the space inside the wormhole, for instance, but it doesn’t make any sense to associate a certain amount of mass with a region of space-time itself. Such a wormhole would also be unaffected by, say, gravity, for similar reasons. This does admittedly make it somewhat tricky to move a wormhole around; for now I’ll handwave it and say you can do it via electromagnetic confinement, but I feel rather guilty about giving such a terrible explanation.

(I do appreciate that it’s rather hard to build a story around this style of wormhole, though I can think of a couple of resolutions. For instance, perhaps the topological anomaly requires a whole complicated housing and power supply on each end, satisfying the ‘difficult to maintain’ portion of the spec? You could even say that this gets more and more difficult to create the bigger the wormhole is, neatly explaining why only the Gardners could make wormholes big enough for evolution-meddling.)

Oh, and by the way, here’s a cool picture of a (realistic) wormhole I found while researching all of the above (https://en.wikipedia.org/wiki/File:Wurmloch.jpg):

Ares Land wrote: ↑Fri Jan 29, 2021 7:54 am I'd love to see the 'Bug War' trope done right, so that might happen.

The story of Ropemaker and Mother Root (I believe those were their names, at least) from the Bugs thread was intriguing, and the Bugs (the illustration actually made them look vaguely amphibious, like newts, or maybe axolotls, unless I'm misinterpreting them greatly) have the potential to be quite sympathetic, I think, at least with things told from their perspective (especially if it's framed in a way that the things humans would find disgusting are not made obvious, which would probably be how I would handle it, to express that these are normal to the Bugs).

Ares Land wrote: ↑Fri Jan 29, 2021 7:54 am What would happen is that Bug planets are very hospitable to humans, except for, you know, the natives trying to kill you. So they'd be prime real estate, for Earth humans or people with a comparable level of development.

Neo-Neocolonialism?

Ares Land wrote: ↑Fri Jan 29, 2021 7:54 am On the other hand, the Yttes (Yttesicans?) would see Bug civilization as valuable in itself but would have no need for planetary real estate.
(Of course you'd have Earthpeople defending the Bugs and Yttesers who can't stand the damn beasts.)

Among Bugs, there'd be some willing to make an alliance and share the planet, as long as the humans get rid of their rivals.
So an actual Bug War would see humans and Bugs fighting alongside in both camps.

All involved being sentient, I would expect a wide range of opinions among each on all points in question.

bradrn wrote: ↑Fri Jan 29, 2021 8:09 am [Note: I wrote all of the below stuff before I saw your link to that Cramer article. However, I found that article somewhat unhelpful in resolving my complaints about this particular wormhole system, so I’m leaving this post as is in the hope that someone can help me understand what I’m getting wrong in my reasoning.]

I'm probably going to disappoint you on this. I'm woefully unqualified to answer these questions!
Basically I got the system from Kip Thorne with the understanding that it would be more plausible than anything I could come up with!

Instead of trying to come up with an inadequate explanation, I'll just link to more articles by Kramer:
https://www.npl.washington.edu/av/altvw33.html
https://www.npl.washington.edu/av/altvw39.html
(The second one has an interesting thought experiment on why wormhole ends would gain/lose mass)

The mass, charge and angular momentum of the black hole are associated with the singularity of the wormhole, rather than the whole black hole being a single solid object described by those properties.

Ah, this I do know! You can't get to the singularity, So essentially a black hole is entirely described by these properties. (Or as Stephen Hawking put it, black holes have no hair).

[Re: preventing time travel by wormhole collapse] Sorry, I still don’t quite understand how this work.

I don't really understand it fully. (I understand this is due to 'quantum effects' which might as well be magic for all I know.)
How it would actually works is described here:
https://arxiv.org/pdf/hep-th/9202090.pdf
(See especially from page 14 on.)

@zompist: the earlier pages seem to treat the time shift bit as granted. There's probably a very solid reason why this is so, but I don't understand it fully!

Hopefully, the best thing would be for someone with a solid knowledge of the theories involved to translate this for us.

The Big Potato itself.

Yttes is the moon of the planet Thasto ['t̪ʰas.tʰo] (<t> is apical alveolar, <th> is laminal-dental), in a binary system with two G stars.

Thasto is well within the habitable zone and has been terraformed. Still, it's only really habitable near the coast. The interior of its one continent is a nastier version of the Gobi desert.

Yttes itself is home to seven billion people. Picture, if you will, a potato wrapped in tin foil, with solar panels extending on top, and antennae and cooling towers jutting around like sprouts. It's about 140kmx80kmx35km -- neglecting the third dimension, that makes it about the size of Porto Rico.
(The solar arrays extend quite a bit beyond that)
In fact, we shouldn't neglect the third dimension. In fact, the Yttesians live inside the moon. It has changed quite a bit as well; in its natural state, it was a captured asteroid, about 10 kilometers in diameter.
The population is estimated at 7 billion.

Let's keep touring the system a bit; you'll find many other such asteroid habitats, both around Wynthem (['wɯn̪.t̪em, Thasta's primary) and its companion sun, Charh [t͡ʃar̥].

The second planet out from Charh is 'Allun ['ʔal.lʌn], the original home planet of the Yttesian humans.

A bit of history

Either because of random chance, or because of some as yet unidentified factor, agriculture started fairly early on 'Allun, and the 'Allunan humans kept their head start.

2400 years before present (when Rome was defended by geese, and China still a bunch of Warring Kingdoms), the 'Allunans had already exhausted their oil reserves, severaly damaged their environment.
They ended up bombing themselves back to the stone age.

Thasto was, at the time, uninhabitable but more promising than say, Mars. An early colony project was in progress. The moon(*), Yttes, served as a source of water, organic materials, and as a port of call for researcher and would-be colonists from 'Allun.

Thasto was more hospitable than Mars, but that's really setting the bar very low. It was, at the time, a hellhole, and the colonits there had no chance of surviving the end of 'Allun as they know it. It was bombarded with heavy radiation, water was locked in the deadly (**) polar regions, and power generation was a nightmare, with the endless dust storms. Also, the dust got everywhere, your lungs included.

Counter-intuitively, Yttes was heaven by comparison. It was a simple matter of digging into the ground to reach a cave system, which could be enlarged easily. There you had natural protection from radiation. Power was a simple matter of putting up solar cells on the surface. And about any material was within easy reach. You just had to dig. That included water, useful for life and as a source of rocket fuel.
Oh, and when I say 'you just had to dig', I should perhaps note that Yttes gravity is negligible and that the matter is loosely held together. It's not quite a matter of just pushing stuff aside, but close.

Anything that could be had in the system was within easy reach. (The delta-v to get, well, pretty much anywhere in the Charh-Wynthem system is very reasonable. There's no gravity well to get out of, you see.)
As it happens, there was something of a permanent base below Yttes surface, in the shape of an habitat module, rotating for gravity.
A larger rotating module was set up, for refugees from the surface. One particularly vicious storm later, and most of the planetary colony had retreated to Yttes.

As it happens, one of the major powers that had fought each other during the global war had an emperor for ceremonial head of state. An imperial scion happened to be in transit when the bomb exploded.

There were enough royalists to proclaim her empress.

Fast forward 2500 years.
The largest human population in the system is now on Yttes. They just kept adding habitat modules inside the moon as population grew. Eventually, asteroid rock had to be pushed aside, and the asteroid to be enlarged to fit these.

The original modules are now museum pieces of course, and as quaint as that wood hut they found on Capitol Hill. While habitat module come in all sizes and shapes, the standard one is a sphere, with a radius of 800 meters, rotating once a minute. This provides about 5.5 sq. km. of usable space at reasonable gravity levels; the total area is 8 sq. km.

There are about 70,000 of these now, all interconnected in a 3 dimensional maze of zero gravity corridors. (***)

Only about one eigth of the original asteroid material has been consumed. Some mass has actually be added (so that Yttes would have easy access to a variety of necessary element). The rest has been placed over and between the habitat modules. It's still being mined; but its primary purpose is that of a radiation shield and heat sink.
Power is supplied by a massive array of solar cells; Yttes is autonomous in terms of food and breathable air. Yttes has about the population of Earth and is equally, if not more self-sufficient.

The weird historical oddity of having an empress survived the test of time. Early settlers seems to have practiced a general rule of 'if it ain't broke, don't fix it'. The early empresses made themselves useful as the rest of the colonists, they never attempted to go against consensus rules. Anything done twice in Yttes became a tradition.
These days the role of the empress (they're always empresses) is entirely ceremonial. Well, in theory. It's hard to say how much influence she has behind the scenes, as empresses are careful to keep it, well, behind the scenes.

Seven billion is a huge number, of course, but it seems tiny compared to the size of the Galaxy. In fact it's largely sufficient, for several reasons:

• [*}The Galactic Empire isn't actually, well, Galactic. It traditionally tries to encompass all hominid-inhabited worlds and any interesting planets in between. It's more of a diffuse cloud, really. (****)
• No culture is as advanced technologically as Yttes. Only a handful can compete with it -- and these gave the empire some trouble, I can tell you. Most are still at a pre-modern stage.
• The Galactic Empire reigns, but does not rule. In practice it sets itself up as sole owner of the wormhole network and as arbiter between smaller polities. It maintains troops in a number of historical trouble spots. The last interstellar war was (making it fit as best it can within our calendar) in the early 20th century, and it was very traumatic for all involved.

(*) Thasto actually had a second moon before. That one was sacrified for its water as part of the terraforming process.
(**) At the time, all of Thasto was deadly, really. I just mean that the polar ice caps were even more so.
(***) Some corridors are large enough to be themselves rotated for gravity. Not surprisingly, Yttes has a very precise understanding of motion and can offer anything from medication to gene therapy to the visitor.
(****) There are stars, towards the red end of the spectrum, you can't send a wormhole to. People generally assume they belong to a separate wormhole network, built by a species that likes red dwarfs. Generally, the Empire has very little idea of what goes on around non-sunlike stars. Knowledge of the oceanic depths of super Earths is likewise restricted, as are gas giants, tidally heated moons and other different places. Yttes keeps laboraties near some of these places, but it can't be said the Empire rules them. The Empire, likewise, doesn't meddle in Bug affairs, though they are probably the one human culture to understand Bug language.

Ares Land wrote: ↑Fri Jan 29, 2021 7:54 am

zompist wrote: ↑Fri Jan 29, 2021 5:21 am I think the last line is physically impossible. You launch the wormhole end in Year 0. By your own account, it arrives in Massotis in around 100.

You're saying that you can look through in year 0 + 1/6 and see Massotis. But that's not possible: the wormhole end didn't arrive there yet. (And from its own perspective, it's not 2 months from Yttes, but about 2.5 hours.)

The problem here is, I know wormholes would work that way because Kip Thorne say they do, but I can't explain why. I don't really understand it.
(A preview of Black holes and time warps where he mentions the temporal paradox consequences: https://archive.org/details/blackholest ... 0/mode/2up)
And here's where I ripped the whole process from: https://www.npl.washington.edu/AV/altvw162.html

I can't read the Thorne article 'cos of too many missing pages, but I see that Cramer definitely has the same scenario you do.

And, I'm sorry to harp on this, but it makes no sense. A thought experiment: you send two wormhole ends from Yttes toward Massotis. Wormhole A makes it, in a hundred years. Wormhole B is hit by a cosmic bus three months out, and is sent careening off, and never comes near any stars.

The question: Two months after the experiment, you look through both wormholes. What do you see?

Note, it's a month before the accident— it hasn't happened yet. The wormholes and Yttes cannot anticipate it. How does wormhole A know that it will eventually reach Massotis so you can see it? Does wormhole B know it will be hit by a bus, and therefore show you interstellar space, or does it not know the future, and therefore show you a picture of Massotis which it will never see?

Ares Land wrote: ↑Fri Jan 29, 2021 9:10 am

bradrn wrote: ↑Fri Jan 29, 2021 8:09 am [Note: I wrote all of the below stuff before I saw your link to that Cramer article. However, I found that article somewhat unhelpful in resolving my complaints about this particular wormhole system, so I’m leaving this post as is in the hope that someone can help me understand what I’m getting wrong in my reasoning.]

I'm probably going to disappoint you on this. I'm woefully unqualified to answer these questions!

Ah, well, so am I. My quantum mechanics is at novice-level, and my relativity is practically non-existent, so I’m not quite sure about this stuff either. (Not only that, my university has dropped its third-year relativity units, so I doubt I’m going to learn it any time soon!)

Basically I got the system from Kip Thorne with the understanding that it would be more plausible than anything I could come up with!

Instead of trying to come up with an inadequate explanation, I'll just link to more articles by Kramer:
https://www.npl.washington.edu/av/altvw33.html
https://www.npl.washington.edu/av/altvw39.html
(The second one has an interesting thought experiment on why wormhole ends would gain/lose mass)

Thanks! I’ll have to read through those properly.

The mass, charge and angular momentum of the black hole are associated with the singularity of the wormhole, rather than the whole black hole being a single solid object described by those properties.

Ah, this I do know! You can't get to the singularity, So essentially a black hole is entirely described by these properties. (Or as Stephen Hawking put it, black holes have no hair).

I think we’re saying the same thing here. You can’t get to the singularity — so there isn’t actually anything in the black hole, and an infalling observer sees it as empty. That is, you can’t really describe a black hole as being a ‘physical object’ in the normal sense of the world.

[Re: preventing time travel by wormhole collapse] Sorry, I still don’t quite understand how this work.

I don't really understand it fully. (I understand this is due to 'quantum effects' which might as well be magic for all I know.)
How it would actually works is described here:
https://arxiv.org/pdf/hep-th/9202090.pdf
(See especially from page 14 on.)

Though I admittedly am struggling to understand this article, I’m not sure it says what you think it says. The author seems to describe how, if you try to travel backwards in time in a single wormhole, the vacuum polarization through the wormhole will conspire to destroy it. He says nothing about loops of wormholes (‘Roman rings’, to use the accepted name) and particles looping around them, and the whole section seems highly speculative in any case.

zompist wrote: ↑Fri Jan 29, 2021 5:10 pm

Ares Land wrote: ↑Fri Jan 29, 2021 7:54 am

zompist wrote: ↑Fri Jan 29, 2021 5:21 am I think the last line is physically impossible. You launch the wormhole end in Year 0. By your own account, it arrives in Massotis in around 100.

You're saying that you can look through in year 0 + 1/6 and see Massotis. But that's not possible: the wormhole end didn't arrive there yet. (And from its own perspective, it's not 2 months from Yttes, but about 2.5 hours.)

The problem here is, I know wormholes would work that way because Kip Thorne say they do, but I can't explain why. I don't really understand it.
(A preview of Black holes and time warps where he mentions the temporal paradox consequences: https://archive.org/details/blackholest ... 0/mode/2up)
And here's where I ripped the whole process from: https://www.npl.washington.edu/AV/altvw162.html

I can't read the Thorne article 'cos of too many missing pages, but I see that Cramer definitely has the same scenario you do.

And, I'm sorry to harp on this, but it makes no sense. A thought experiment: you send two wormhole ends from Yttes toward Massotis. Wormhole A makes it, in a hundred years. Wormhole B is hit by a cosmic bus three months out, and is sent careening off, and never comes near any stars.

The question: Two months after the experiment, you look through both wormholes. What do you see?

Note, it's a month before the accident— it hasn't happened yet. The wormholes and Yttes cannot anticipate it. How does wormhole A know that it will eventually reach Massotis so you can see it? Does wormhole B know it will be hit by a bus, and therefore show you interstellar space, or does it not know the future, and therefore show you a picture of Massotis which it will never see?

I’m not sure I understand this objection. The whole point of these wormholes is that they’re portals into the future. That is, when you look through them, you see the surrounds as they are at some future time, rather than as they are presently. As such, when looking through B, you will see it as it is in the future — after it has been deflected from its course.

bradrn wrote: ↑Fri Jan 29, 2021 6:20 pm

And, I'm sorry to harp on this, but it makes no sense. A thought experiment: you send two wormhole ends from Yttes toward Massotis. Wormhole A makes it, in a hundred years. Wormhole B is hit by a cosmic bus three months out, and is sent careening off, and never comes near any stars.

The question: Two months after the experiment, you look through both wormholes. What do you see?

Note, it's a month before the accident— it hasn't happened yet. The wormholes and Yttes cannot anticipate it. How does wormhole A know that it will eventually reach Massotis so you can see it? Does wormhole B know it will be hit by a bus, and therefore show you interstellar space, or does it not know the future, and therefore show you a picture of Massotis which it will never see?

I’m not sure I understand this objection. The whole point of these wormholes is that they’re portals into the future. That is, when you look through them, you see the surrounds as they are at some future time, rather than as they are presently. As such, when looking through B, you will see it as it is in the future — after it has been deflected from its course.

And I'm saying that's impossible. At t+2 months, there is no link to the future— neither wormhole is at Massotis.

I hate to accuse a physicist of making an error, but they're speculating wildly and it's easy to make a wrong turn logically. I think they're focusing on the wormhole once it's at Massotis, and then forgetting that it made a journey that takes time, both in the galactic frame and in wormhole frame.

zompist wrote: ↑Fri Jan 29, 2021 6:44 pm

bradrn wrote: ↑Fri Jan 29, 2021 6:20 pm

And, I'm sorry to harp on this, but it makes no sense. A thought experiment: you send two wormhole ends from Yttes toward Massotis. Wormhole A makes it, in a hundred years. Wormhole B is hit by a cosmic bus three months out, and is sent careening off, and never comes near any stars.

The question: Two months after the experiment, you look through both wormholes. What do you see?

Note, it's a month before the accident— it hasn't happened yet. The wormholes and Yttes cannot anticipate it. How does wormhole A know that it will eventually reach Massotis so you can see it? Does wormhole B know it will be hit by a bus, and therefore show you interstellar space, or does it not know the future, and therefore show you a picture of Massotis which it will never see?

I’m not sure I understand this objection. The whole point of these wormholes is that they’re portals into the future. That is, when you look through them, you see the surrounds as they are at some future time, rather than as they are presently. As such, when looking through B, you will see it as it is in the future — after it has been deflected from its course.

And I'm saying that's impossible. At t+2 months, there is no link to the future— neither wormhole is at Massotis.

Hmm. Personally, I somehow doubt that the time link suddenly gets established as soon as the wormhole arrives at its destination, which seems to be what you’re arguing. (This poses numerous philosophical problems — how does the wormhole ‘know’ when it gets to its destination?) I suspect something more like the following schematic plot of wormhole time against Earth time:


That is, the Δt between the ends of the wormhole starts at 0, increases steadily as it is transported, and eventually ends up at a maximum as it is decelerated.

I hate to accuse a physicist of making an error, but they're speculating wildly and it's easy to make a wrong turn logically. I think they're focusing on the wormhole once it's at Massotis, and then forgetting that it made a journey that takes time, both in the galactic frame and in wormhole frame.

Oh, I agree it’s easy to make errors in this stuff. (You’ll see I’m also arguing against some behaviours of these wormholes.) But I think they got this point correct.

zompist wrote: ↑Fri Jan 29, 2021 5:10 pm I can't read the Thorne article 'cos of too many missing pages, but I see that Cramer definitely has the same scenario you do.

And, I'm sorry to harp on this, but it makes no sense. A thought experiment: you send two wormhole ends from Yttes toward Massotis. Wormhole A makes it, in a hundred years. Wormhole B is hit by a cosmic bus three months out, and is sent careening off, and never comes near any stars.

The question: Two months after the experiment, you look through both wormholes. What do you see?

Note, it's a month before the accident— it hasn't happened yet. The wormholes and Yttes cannot anticipate it. How does wormhole A know that it will eventually reach Massotis so you can see it? Does wormhole B know it will be hit by a bus, and therefore show you interstellar space, or does it not know the future, and therefore show you a picture of Massotis which it will never see?

Let's assume wormhole B hits the cosmic bus three months out from Yttes perspective. (if it were three months out by its own perspective, well, it would already be at Massotis).

That means it's hit by the bus 3.7 hours after launch from its own perspective. You can see the accident from Yttes if you look through the wormhole hole 3.7 hours after launch. If you look through it after two months you see interstellar space.
(If you look through Wormhole A after two months you see Massotis).

Yttes figuring out 'in advance' that there's a space bus three months out isn't a problem; no one in Yttes can do anything about the event.
Suppose you aim your laser at the bus as soon as Wormhole B is hit... The laser beam will, at best, hit the bus three months plus 3.7 hours -- too late to prevent the accident.

Another way to look at it: from Yttes perspective, it is at rest and wormholes A and B are moving at close to lightspeed. From wormhole B perspective, it is at rest and it is Yttes that is moving at close to lightspeed. Both perspectives are equally valid under relativity.

bradrn wrote: ↑Fri Jan 29, 2021 6:20 pm Though I admittedly am struggling to understand this article, I’m not sure it says what you think it says. The author seems to describe how, if you try to travel backwards in time in a single wormhole, the vacuum polarization through the wormhole will conspire to destroy it. He says nothing about loops of wormholes (‘Roman rings’, to use the accepted name) and particles looping around them, and the whole section seems highly speculative in any case.

I agree that this considers a single wormhole. I think a similar thing will happen to a Roman ring configuration.

Of course all of this is speculative; I'm using this concept because it's got a bit more scientific caution than hyperspace jumps... but I won't be buying wormhole futures yet

(From a conworlding perspective, the weird relativistic stuff gives the wormhole idea an interesting spin, but honestly I don't plan to ever do anything with it. As far as I'm concerned, the wormholes are magic wardrobes in space.)