Dyson Spheres and the Mile High Club

Chaos Manor Mail, Sunday,October 18, 2015

Tuesday, October 20, 2015

We have had more mail on the possible – well, not quite impossible – Dyson sphere than we have had for any other topic this year. It has also sparked some discussions, at least one of which I’ll post here.

Understand that this is all speculation, laced with the bit of reality we know.

Thanks for the blow-by-blow over the proposed Dyson sphere in your blog! It was a nice boost to hits on my website too! [Now they just need to look at my books and buy a few! 😉 ]

Also do let your readers know that I would be delighted to have discovered an intelligent…FRIENDLY…race out there. It’s just that, as a scientist, I am trained as a skeptic. And the least probable explanation is NOT the one that should be immediately jumped upon as the purported solution.

Speaking of books, I do have a new one coming out in just a few weeks. You might enjoy it — the Gentleman Aegis series is a prequel to the Displaced Detective, with a young Holmes in his original spacetime continuum, and a young Watson, trying to establish themselves in London; they are mid-20s at the most. Cases are few and far between as yet, and so when one of Holmes’ old professors invites the pair to join his expedition to Egypt to find the tomb of the first Pharaoh, expenses paid, salary offered, they jump at the opportunity. But what they find is…quite different. The first book is called Sherlock Holmes and the Mummy’s Curse.

Rather than try to mimic Doyle’s style, I use my own established writing style — though I do use entirely Victorian British English throughout, complete with the more archaic spelling of the period. It’s a much more traditional Holmes story than any you’ll find in the Displaced Detective series — which is as it should be; I wasn’t trying to write traditional Holmes in that, but I am in the Gentleman Aegis books. The tone is intended to evoke both Doyle and early pulp novels, without outrightly imitating either, and it is YA-friendly. Yell if you’d like a review copy as soon as I’ve gotten the eARC in hand. Tentative release date is 1 Nov, though since I’ve seen neither the eARC nor galleys, that might slide a bit.

I’m also working with one of my proteges on book 4 of the Cresperian Saga, titled Heritage. It’s a shared universe (so far 4 different authors have written in it!) that is sort of a blend of space opera and milSF. And eventually I’m going to manage to finish the sequel to my first novel, Burnout. That one’s going to be called Escape Velocity. But since Burnout managed to semi-predict what happened to Columbia when it broke up during re-entry, and I had a friend aboard when it did, the sequel is proving difficult to pry out of my brain, as you might expect. If I can ever convince Travis Taylor to shake loose from all his other projects, we’ll write the two sequels to Extraction Point — that’s definite milSF/mystery/spy stuff — and I’m still looking for an agent for my steampunk series.
Stephanie Osborn

“The Interstellar Woman of Mystery”

This is a long dialog between Stephanie Osborne and James Crawford, with here and there a comment by Dr. Jim Woosley, physicist and rocket scientist. It is an interesting introduction to the problems of Dyson Spheres and other enormous objects. It gets somewhat technical, but it should be comprehensible to most readers.

It wanders from the concept to a brief discussion of embryology in space. Those who are interested in this sort of thing should be very interested. Others might find it less so. I don’t know what happened to the formatting but I have not time to fix it.

Dyson sphere discussion

Jumping off from Jerry’s blog post, dated 16 October 2015:

James Crawford:

The reported observations are intriguing. However, since the only reports I have read 

are in popular media rather than

 astronomical journals, I am not confident in the accuracy.

Perhaps the most mystifying aspect is the absence of IR emissions that should be 

proportional to the decrease in emissions

 in the visible spectrum. A Dyson sphere should be in thermodynamic equilibrium with i's star, 

so IR emissions should equal the output of the star.

Might I suggest that this star is the home of a Dyson swarm composed of large numbers of solar collectors that depend in part on light pressure to balance the pull of gravity. The flaw in this commonly accepted idea is that if the IR emissions are radial from the star, then the light pressure from IR emissions will equal the equal the light pressure from absorbed radiation. This flaw in the concept can be remedied by having an array of heat radiators that are structured to emit IR primarily in directions normal to radial from the star.

I would also make the observation that even a star-faring civilization would probably find variations of a Dyson sphere economically advantageous over interstellar colonization. If the economic cost is proportional to energy use, then the cost of interstellar colonization is immense. Even slower than light vessels that transit at only 0.cu would require on the order of 4×1014 Joules per kilogram. If each colonist requires only one ton of equipment and starship, then the energy cost per colonist is then about 4×1017 Joules or 100 megatons.

This is the equivalent to 100 Megawatts of power utilized over a life span of a century compared to just a few kilowatts per capita for current, industrialized societies. Building a Dyson sphere would probably require several orders of magnitude less energy per person than a starship.

Stephanie Osborn:

[Add: The technical articles have a very different slant. But every single popular media article has had the Artificial Construct slant on it, some even declaring it to be absolutely so.]

As Jerry and I have been discussing with the physicist friend, any civilization sophisticated enough to be able to build any sort of large orbital construct would be radiating a crap-ton of communications. And as close as the star is, we WOULD be hearing it. And it would be STRONG. As Dr. Woosley pointed out in a separate email, it would probably be one of, if not the, brightest object in the sky at whatever wavelengths were being used for comm. But it isn’t.

If you’re thinking in terms of a kind of solar sail for power gathering, you don’t need the light pressure to maintain the position — it has to be in orbit already. It can’t/won’t just hover. Which then means that the things have to be CORRECTED for the effects of light pressure…which provides yet another kind of signal we would expect to detect, and don’t. Besides, if you’re using it as a solar collector, the IR is precisely what you want to make use of, not radiate off into space.

Also, the problem with any sort of variant of a Dyson sphere is that all of the planets in the system, including the homeworld, and all of the asteroids, comets, and any other material they can get their hands on, has to be broken down and put into the building of the construct. Worse, if much of the non-stellar mass of the system is bound up in gas giants, much of that mass becomes unusable for actual construction — what can you build with four planets’ worth of hydrogen, methane, and the like? You can certainly use it for power, either by straight burning or by fusion (assuming such an advanced civilization got past the “Just twenty more years” conundrum), but you can’t MAKE anything with it.

So in the end, venturing out of the system really IS more cost-efficient in the long run, all forms of cost being taken into consideration.

James:

The idea of Dyson sphere variant comprised of hovering light sails is NOT my idea but is just one of the many variations of the Dyson sphere concept that I have read about. In my own humble opinion, a very large number of habitat modules in orbit with very slightly greater than orbital velocity and tethered together to maintain order somewhat like Niven’s shadow squares seems to be the most plausible variation of the Dyson sphere concept. You get a structure with a living area equivalent to a Ringworld without the need for absurdly strong construction materials (Niven’s sculpting of features in the Scryth isn’t feasible without a level of stiffness that is orders of magnitude more absurd than the tensile strength of a simple cylinder spinning at greater than orbital velocity to simulate gravity). As Niven pointed out in his non-fiction Bigger Than Worlds, you could have multiple ring structures of slightly varying diameters at various orbital inclinations that could approximate a sphere.

As to the IR emissions level, it is dependent on conversion efficiency and what is being done with the energy. Unless the aliens are directly converting energy into mass, boosting mass to a higher elevation (stellar uplifting?) or boosting mass to high velocity, the energy absorbed will eventually be transformed into heat which they will radiate away if they don’t want to broil themselves.

As for our ability to detect communications, this is dependent on what they are using for communications. Most of the variations on a Dyson sphere or Ringworld enable communications via fiber optics, eliminating the need for EM transmissions. Sufficiently advanced aliens might communicate via pulsed and modulated Neutrinos or gravity waves. They might even communicate via dancing and feather displays or nuanced flatulence. My point here is that the argument that there is no civilization because we can’t detect their EM transmissions is comparable to aborigines arguing that modern civilization doesn’t exist because they can’t see our smoke signals.

Stephanie:

Actually, I beg to differ on the structural component. Unless you have an artificial gravity FIELD (as in manipulating bosons to create artificial gravity, assuming that’s possible), you still have to spin up the structure to simulate gravity. You can’t simply have a few things tethered together with just enough strength to keep ’em in one general area. You have to have a structure capable of withstanding the forces of being accelerated INTO a spin to begin with, then maintaining that spin at a constant angular velocity. Not that you have to have “absurdly strong” materials; I’m not proposing unobtainium. But the constituents of a gas giant planet aren’t going to do you much good as building material, no matter what. Yes, you can propose using the metallic hydrogen at Jupiter’s core, but as soon as you take it out of Jupiter’s core, it ceases to be metallic, because the conditions that force it into that state have been removed. [EDIT: Reminder – a Dyson sphere’s construction would require on average more materials than is present in the average stellar system to begin with, outside the central star.]

(And I understand the concept wasn’t your idea; I recognized it. But just because an engineer has proposed something doesn’t automatically mean it’s gonna work. My graduate work was in astronomy/astrophysics, specifically binary variable stars, so I have a pretty good grasp of orbital mechanics. I worked the Tethered Satellite reflight mission, and I told some friends what was going to happen to it months before launch, simply based on the orbital mechanics of the system. And hey presto, it happened. And while I love Larry, and think he writes terrific stuff — especially with Jerry! — one must remember that science fiction does not necessarily equal science fact. I write hard science fiction myself, given my background, but I still often have to stretch the theory to achieve the dramatic effect I want.)

Any excess heat gets radiated away, sure. But again, it will generate an abnormally-high IR signal, which we would detect, and probably pretty readily at the short distance (at least in astronomical terms) we’re talking about.

As for communications, it doesn’t matter what they use to communicate. If the sphere/circle is broken, not continuous, then transmission of SOME SORT has to occur between the different clusters of civilization. And we astronomers/astrophysicists have observing systems set up for pretty much the entire electromagnetic spectrum, AND gravity waves, AND neutrinos, and just about anything else that could be naturally or artificially emitted. (FWIW one of my friends happens to be Claudio Maccone, the head of the SETI Permanent Committee of the International Academy of Astronautics, and he and I have talked about various ways to communicate efficiently between stellar systems, among other things. That pretty much has covered all of this stuff we’re talking about.) And as such, this system would have to be the brightest thing going in the sky, in whatever they were using to transmit. And we would have noticed it as such — could hardly fail to do so, in fact.

I’m sorry if this information is disappointing. But I’m a scientist, and a scientist is a trained skeptic. My job is to look at the hypothesis and see how many holes I can poke in it; what’s left over when I’m done is the only real part, and if it doesn’t hold together, it has to be thrown out and a new hypothesis devised. I’m not saying absolutely this observation is not another civilization. But I am saying that the probability is so very low as to rate it pretty much last on the list of possibilities.

James:

I am not overly excited about this anomaly or wedded to the idea that it is an alien artifact. I am just contemplating the possibilities and commenting about the possibly flawed assumptions in the deliberations.

The major advantage of the idea to build a shell of light sails that support themselves via light pressure is that it seems to be about the only plausible method to create a fully spherical structure that completely encloses the star to capture the entire output using the probable supply of structurally useful materials in a stellar system. The idea seems to serve no useful purpose.

The suggestion of individual habitat modules that are tethered together into a ring is predicated on the assumption that the individual modules are spherical, cylindrical or toroidal that can contain atmosphere and be spun up to produce simulated gravity. Such structures would be sized to whatever materials technology is available to the builders. If strength of available materials limits them to smaller structures, they will build more of them.

It is important to remember that any civilization that is both capable of building such a megastructure and has a need for such a megastructure is probably old by our standards and has felt the need to move its large and gradually growing population off-planet. They might have evolved or genetically engineered themselves so that they can not only survive but thrive in a microgravity environment or perhaps even survive prolonged periods in vacuum.

Any discussion of alien civilizations needs to keep in mind the basic premise of Greg Bear’s Forge of Heaven and Anvil of Stars. It might be that we live in a dangerous universe where it is wise not to advertise your existence and draw the attention of malevolent aliens who believe that one should do unto others before they do unto you.

Finally, we shouldn’t ignore the possibility that this megastructure is merely an artwork or monument that serves no useful purpose except perhaps a political statement.

Stephanie:

Let’s look at the concept of a Dyson sphere for a moment.

And let’s assume for purposes of this discussion that we have sufficient, and strong enough, material to build one, and that we’ve built a complete sphere around the Sun, at the radius of Earth’s orbit. And for purposes of simplicity, let us assume that we can generate artificial gravity fields using boson manipulation, so we don’t have to worry about spinning the thing to generate simulated gravity. (Because, frankly, I don’t want to have to think right now about what to do with the orbit if it has to spin faster than Earth revolves, in order to generate simulated gravity. I know it would have to be smaller, but HOW MUCH smaller, and would it possibly take the sphere out of the Goldilocks zone, blah blah. I’ve been busy researching my next book, and intended to take some time off, for a change!)

So — the equator of the sphere is in Earth’s orbit and is more or less stable, save for the fact that it’s circular and not elliptical. I guess I should rather say that its radius is Earth’s average distance from the Sun, with its equator in the plane of the ecliptic. It’s more precise, so.

But…as we get farther and farther away from the sphere’s equator, and up toward the poles, we start running into more and more severe problems with the orbital mechanics. Because in those regions, we are not orbiting the center of mass of the system (which will be very near the Sun’s center). Instead, we are “orbiting” a point offset to north or south of the center of

mass. It is “orbiting” the axis of rotation, certainly, but it is NOT orbiting the CENTER OF MASS. Nor can it, and maintain the sphere’s structure.

Therefore, the orbital motion is NOT offsetting the gravitational forces of the Sun on those parts of the sphere.

Assuming it could be built to begin with (doubtful), it would rapidly start to deform, flattening into a very oblate ellipsoid, and probably eventually collapsing in the polar regions, with the fragments falling into the Sun. In order to build such a structure and have it remain stable for any significant length of time, we would have to invoke adamantium, unobtainium, and probably several different kinds of gravitational field negators on a truly massive scale. In short, we have jumped the scientific shark and are now in the realm, not even of hard science fiction, but of space opera.

And this is true regardless of how we attempt to build a Dyson sphere. Even your shell of relatively unconnected solar collectors suffers from this problem. In order to construct the thing, each component MUST orbit the CENTER OF MASS OF THE SYSTEM, or it falls apart very rapidly AS IT IS BEING BUILT. But the problem with that is that you will have the components’ orbits crossing, which leads to catastrophic chaos. You can place them at slightly varying distances, but now you have gravitational forces between the components as they pass to contend with, which will distort the orbits over time and lead to collisions, and the system will rapidly deteriorate after that.

In short, a ringworld is the ONLY such construct which has a hope of working. And it has its own problems: the orbit must be circularized, and perfectly circular orbits are NOT natural, and tend to be easily perturbed into elliptical orbits, which then deforms a solid ring to the point of breaking, and which will tend to result in collisions between components if the ring is unconnected. (Accelerating as they near periastron, decelerating as they approach apastron, etc.)

You can say, okay, fine, that’s a simple fix: we’ll build stationkeeping ability into the components. But that’s not as easy as it seems: since the retirement of the Shuttle, we have some difficulty just maintaining the orbit of the ISS. (We used to use the Shuttle Orbiters themselves to boost the ISS when they were docked, because solar activity causes the outermost layers of the atmosphere to ‘swell,’ increasing drag.) But we have just used all of the mass outside the Sun for building our construct, and now we have to find material for multiple thrusters for each component, AND material for FUEL for those thrusters, in perpetuity. But we have not gone to another stellar system, and we have exhausted our own system’s resources. We cannot build in stationkeeping.

It is therefore improbable that such a structure can be built which will remain stable for any significant length of time.

And I still maintain that, once the breakthrough to interstellar travel has been made, it will be eminently more practical and less mass-energy-intensive than attempting to cannibalize one’s entire parent system in an effort to obtain enough suitable mass to build a decent stellar-centric structure. More, the requirement to keep said structure stable virtually necessitates interstellar travel, in order to provide the additional resources for stationkeeping capability. I also maintain that this very problem (problem in toto, that is to say, mass/energy requirements) precludes the building of a similar structure simply for the purpose of a work of art, political statement, or the like. To throw the resources of an entire stellar system into the construction of a non-usable, inherently unstable structure, when it could be mined for resources, seems a very unwise use of the material, especially for a space-faring race. It only becomes viable if the race has evolved past the need for such structures to begin with. (E.g. ST:TOS’s Orgainian race.) And at that point I have to wonder if the concept of political statement, or definition of artwork, changes along with the race.

As to bioengineering, that has possibilities. We know of many different kinds of extremophiles even here on Earth, at least one phylum of which, Tardigrada, is postulated by scientists NOT to have originated on Earth. Scientists are already studying their genetics in order to figure out how they do what they do; this study of Deinococcus radiodurans, aka “Conan the bacterium,” is already producing fascinating information.

But bioengineering a humanoid body to handle extremes is one thing; bioengineering them to reproduce those adaptations, in order that babies born in that environment can survive, is another matter. And more, it effectively creates a new species, one which might not be able to return to the homeworld and survive. And that also leads to other problems: you have just fragmented your original species into potentially multiple species or subspecies, which may or may not have that much in common. And that’s quite aside from considerations of bias, bigotry, and prejudice. I mean, for pity’s sake, we have issues with different skin colors within our own species! Can you imagine if we were to start spinning off new species, or even sub-species? (Yes, I know various writers have touched on this exact sort of thing, but stop and think about it in all seriousness for a bit, in real life as opposed to between the covers of a book.) The Civil War, or even WWII, has nothing on what a space-borne civil war would be like.

Just an interesting point: if provided with an oxygen supply, homo sapiens can actually survive for a while in vacuum. It isn’t the zero pressure that kills, but the asphyxiation. Now, it doesn’t do the body any favors, certainly, and if dumped straight from sea level to high-orbital vacuum, generates a very nasty set of the bends, which CAN kill. But if the person prebreathes pure oxygen long enough to eliminate the nitrogen, and drops the atmospheric pressure in stages (what astronauts do for extended EVAs, because spacesuits don’t actually have very high pressure in ’em), then it’s survivable — again, with a supply of O2 to breathe.

And certainly “not advising your presence due to danger” is only one of the various, and varied, solutions of the Fermi Paradox, on which I was privileged to lead a guided discussion at the very first Tennessee Valley Interstellar Workshop. (The introductory presentation for that open-forum discussion has become a fairly popular lecture on the SF convention circuit in the Southeast, especially after I expanded it a bit.) There are quite a few other solutions, as well, several of which might apply in this situation.

But we are still left with the fact that there MUST HAVE BEEN communication of SOME sort during the construction of the object, if only between builders. Communication that we have not observed, but must have done, if it happened.

James:

I finally noticed the link to the professional journal with the actual data. A comet shower caused by an interaction with either a bound star (highly eccentric orbit) or a passing star seems to be the most plausible explanation. An interesting variation of this explanation is intentional cometary bombardment of the system by one faction of aliens versus another. As Pournelle and Niven pointed out in Lucifer’s Hammer, a civilization with decent spacefaring capability (ships with delta-V capability comparable to cometary impact velocity and big enough to deliver a really big nuke to a few AUs from their home planet) should be able to divert a comet from an impact trajectory. Such a civilization might not be able to divert a series of incoming comets targeted at their planet by an attacker. We might be witnessing an interstellar war.
Even though it seems unlikely that this is an alien megastructure or an interstellar war, it is a fascinating object.
http://arxiv.org/pdf/1509.03622v1.pdf

Stephanie:

Yes, that [comet shower caused by stellar interaction] seems to me, rare though even it would be, to be the best explanation so far as well.

And it is indeed fascinating, without doubt. I’ve been carrying on various discussions about it all week.

James:

I confess that I have been dabbling with the idea of writing hard, military Sci Fi. Your commentary

 on the idea of adaptation to space conforms to my own speculation. My basic premise is inspired

 by Gerard K O’Neill's speculation that space, rather than habitable planets, should be the preferred 

habitat for a technologically advanced, industrialized civilization. While I am a heretic who rejects

 Global Warming Theology, projecting human energy use not too far into the future suggests

 that humans will begin to have a profound, negative impact on the environment and climate.

 Moving the bulk of human industrial activity off-planet would then be advantageous. A key feature

 of my speculation is that prolonged exposure to a microgravity environment (Earth's task masters

 demand that production not be diverted to decent habitat for the workers), survivable

 depressurization accidents, followed by reproduction, results in genes expressing 

themselves in unexpected ways. This, combined with natural and sexual selection

 (women will prefer men best adapted to the new environment), results in humans adapting 

to space. The resulting racial conflicts that you comment on are of course inevitable. Given the shift

 of industrial and economic power off planet, the new variant of humans would become the 

dominant civilization. In the absence of high acceleration, high delta-V torch ships, the space 

adapted humans would have the military advantage as well as being economically dominant, 

and Earth would become as disadvantaged as Africa today. Project this situation into 

the future a few centuries. Fusion rocket technology gradually advances so that high delta-V, 

high-acceleration torch ships that are so beloved by Sci Fi authors become feasible, 

but the space adapted humans can't tolerate much more than 0.1g. This isn't a problem for 

peaceful space commerce. Earth humans could ride high acceleration torch ships, 

but they lack the industrial capacity and technology to build them. The space-dwelling offshoot 

of humanity makes damn certain that the planet-bound humans don't have the capacity to 

build ships that can threaten them. (Launching a fusion torch ship from a planetary surface 

isn't a good idea anyway.) This situation persists until the space-based humans meet nasty 

aliens and have to fight a war. Unfortunately; while they can build effective, fusion rocket warships, 

they are physically incapable of piloting them. They are compelled to hire planet dwelling 

humans as mercenaries. 

Stephanie:

Well, there’s a slight problem with that. Namely embryology.

Some of the missions I worked on the Shuttle program had experiments that were the early stages of spacebound embryology. It turns out that there is a real problem with gestating babies of most types in a microgravity environment. Humans haven’t been attempted, for obvious reasons, but there is reason to extrapolate to Homo sapiens. It seems that embryo development is very, VERY tied to being in a relatively strong gravity field. Some species’ newborns/new-hatched lived scarce days beyond birthing/hatching, it was so very sensitive to the environmental change. And that’s JUST the gravity. (How do we know it was the gravity? Complete disorientation and panic in the babies. Uniformly. For all the babies of that species. Not all species behaved so extremely, and some of those species, gestated entirely on-orbit, were able to navigate successfully…until brought back to Earth, whereupon they lost all orientation, panicked, and died shortly thereafter.)

And so then there are other things to contend with, from an embryology standpoint — hard radiation being probably the most significant.

Hence I think that we may well be in big trouble if we just go up there and start trying to have babies to create spaceborne colonies, without either some consideration of what’s happening (and a LOT more research!), or else have the means to do that genetic manipulation we talked about in the previous email. I don’t think it’s going to be nearly as simple as letting it take a natural-selection path.

James:

Could you provide some links to some information on embryo development in free fall?

Given the fact that an embryo is essentially floating in fluid during gestation, I am surprised that the effect is so profound. Is the effect less significant if an embryo is gestated in space then birthed or hatched in gravity? Have there been any experiments where centrifuges were employed to simulate various gravity levels to determine the threshold for the effects?

Your objections actually confirm my highly speculative idea that humans conceived and gestated in space are going to have significant physiological differences and be under enormous selective pressure to adapt to a microgravity environment. Given the indisputable effects of radiation, reproduction would obviously be less risky on the moon or an asteroid mine where plentiful mass for shielding is available.

Your point that reproduction in space is ill advised cannot be disputed. However; whenever

human males and females of reproductive age reside together for prolonged periods of time, reproduction occurs even if it is forbidden. Just ask the US Navy about the pregnancy rates in their mixed gender crews. Factor in possibilities such as transport costs, politics, embargoes or war and it becomes very plausible that humans will be conceived, gestated and birthed in free fall or low gravity environments.

Stephanie:

[DISCLAIMER: Stephanie Osborn does not speak for NASA, makes no claim that the suspected events did in fact and without doubt occur, names no names, and will not name dates.]

Anything I would point you toward at this point could be outdated, as I’ve been retired from the program for some years now. I would recommend that you Google a search string something like, “microgravity embryology” or the like, and see what comes up.

I do not think there have been any centrifuge experiments, as no such equipment has been carried up that I know of. Also realize that embryos, while in fluid of various sorts (uterine or egg), are not neutrally buoyant. And yes, gestation or partial gestation in one environment, followed by birth in the other environment, is the same as gestation & birth in one environment followed by transition to the other. At least in the experiments with which I am familiar.

And I worked the mission that had the first married couple in space in the crew. And while NASA placed them on opposite shifts, we were expressly forbidden from cabin video during shift handovers, and, well, the SAMS (Space Acceleration Measurement System, a means of recording movement of the Orbiter, lets us know if, e.g. we got hit by debris or a micrometeoroid) was also forbidden for anyone not in need of the data to determine safety. I had some friends who had a “need to know,” and…let’s just say we figure the Mile-High Club has a new division.

But my whole point in all this was not to say that space-based reproduction is ill-advised (though it is), but to illustrate that, as things currently stand, there is a high likelihood that a pregnancy might not survive to term, or might not survive much past that, or survive transitioning to a different environment. At least without some direct tinkering to intervene. And there are some highly efficient, semi-reversible means of ensuring it doesn’t happen, as well as some 100% successful, non-reversible means of such. Those should be thrown into the fiction mix — e.g. a very autocratic space venture company forces women on the program to go on the Pill, and men to have a plug inserted. (Plugs can be removed.) I can see, also, the Chinese space agency having their taikonauts permanently sterilized. Soviet Union would likely have done, also. That kind of thing.

James:

They must have a sign reading, “If this shuttle’s rocking, don’t bother knocking.”

Stephanie:

Not goin’ there!

Add to that:

Jerry,

A late note I will add to the conversation:

The big issue is that any type of natural dynamic phenomenon must be unfolding. If as I suggested yesterday this is the breakup of a large body (very large), it’s been recent enough that the debris is not uniformly dispersed across an orbit – making it within a few years of occurrence. The “old star” argument works against a condensing planetary nebula. The 60-day quasi-random occlusion with a 700+ day gap argues for a Mars-sized orbit (or larger for an F3 star) unless it’s a one time phenomenon (again, coincidental), based on the assumption that the 793 day and the 1490-1570 day phenomena in the light curve are related – if not, the orbital period is longer than 1500 days. If it’s a cometary breakup, the initial comet must have been whopping big – I would think significantly larger than Jupiter.

Conversely, if this is a metacivilization capable of engineering on Dyson-sphere levels, but not yet fully enclosed in a Dyson sphere, at 1500 light years we should have detected their RF communications with the first radio telescopes. Even if they don’t use RF, their accidental EME should be the order of one of the brightest RF sources in the sky.

(Incidentally, a fully enclosed Dyson sphere would radiate as a more or less 300 degree kelvin body with a radius of 1 AU….)

Jim

And since he postulated all that to me the other day, and I have had a chance to consider it, I have to say I’m in full agreement with his assessment and back-of-the-envelope calculations (though I haven’t tried to duplicate them as yet). Nevertheless, given the periods, it isn’t hard to estimate radius of orbit, simply by comparing it to planets in our own system.

It is also very true that if it is a civilization advanced enough to be building on that scale, we should be picking up on plenty of comm.

Based on my astronomical experience, I’m inclined to think we lucked out on seeing a rare natural event shortly after it happened. It makes more sense than anything else that’s been postulated to date. And the more we look, the more the probability increases of seeing such an event.

Jim, as the whole thing is all over Faceplant, with your permission, I may use some of this to post, so that people understand how improbable a Dyson sphere/other artificial construct really is.
Stephanie Osborn

“The Interstellar Woman of Mystery”

Irrelevant to the Dyson sphere discussion, but at one point Stephanie got into humans surviving in vacuum and the rather low pressures in space suits. I was involved in design and testing of early space suits, and I became and remain an advocate of higher internal pressures for space riggers. The current pure oxygen at low pressure environment is very limiting. We use it because NASA has more or less reserved space for 30+ year old Ph.D.s rather that 18 year old riggers who can actually do work in space. Higher pressures tire astronauts out. Young riggers endure it and get the job done. But that’s another discussion and appropriate to Dyson spheres.

In the above discussion, Stephanie modestly edited out a couple of posts that I found interestind;

I think I need to start reading your fiction.  With Niven and Pournelle nearly retired, I have the need for a fix of new Sci Fi with rivets in it.

I am not overly excited about this anomaly or wedded to the idea that it is an alien artifact.   I am just contemplating the possibilities and commenting about the possibly flawed assumptions in the deliberations.

The major advantage of the idea to build a shell of light sails that support themselves via light pressure is that it seems to be about the only plausible method to create a fully spherical structure that completely encloses the star to capture the entire output using the probable supply of structurally useful materials in a stellar system.  The idea seems to serve no useful purpose.

The suggestion of individual habitat modules that are tethered together into a ring is predicated on the assumption that the individual modules are spherical, cylindrical or torridial that can contain atmosphere and be spun up to produce simulated gravity.  Such structures would be sized to whatever materials technology is available to the builders.  If strength of available materials limits them to smaller structures, they will build more of them.

It is important to remember that any civilization that is both capable of building such a megastructure and has a need for such a megastructure is probably old by our standards and has felt the need to move its large and gradually growing population off planet.  They might have evolved or genetically engineered themselves so that they can not only survive but thrive in a microgravity environment or perhaps even survive prolonged periods in vacuum.

Any discussion of alien civilizations needs to keep in mind the basic premises of Greg Bear’s FORGE OF HEAVEN and ANVIL OF STARS.    It might be that we live in a dangerous universe where it is wise to not advertise your existence and draw the attention of malevolent aliens who believe that one should do unto others before they do unto you.

Finally, we shouldn’t ignore the possibility that this megastructure is merely an artwork or monument that serves no useful purpose except perhaps a political statement.   You might find it interesting to Google “Stump Wall of Shame” to see the megastructure that I built a few years ago to protest the intransigence of government officials who prevented me from developing my property.   I had logged the property so to enable future development and make it easier to maintain, I dug up all the stumps.   I then used the stumps to build a wall to deny access to suburban neighbors who coveted my land for a park.  I satellite with a really good telescope should be able to see my wall from orbit.   

James Crawford

{Niven and Pournelle aren’t retired, we’re just slow. Admittedly it’s sometime hard to discern the difference, but we’re hard at work on an interstellar colony novel; a sequel to the best sellers Lagacy of Heorot and Beowulf’s Children by Niven, Pournelle, and Barnes.

Hi James (or is it Jame? your email address keeps coming up with Jame, hence my confusion. Sorry.) And I would be delighted if you started reading my fiction. Right now I am focused mostly on a couple of science fiction/mystery genre blend series, one of which is brand new and the first book is due out in a few weeks. There are several things I have which you might like, though, even if you’re not into mystery. And I have some nonfiction stuff out there too, and a steampunk series in the works. My website URL is in my sig file; yell if you have questions about the books. I’ll be happy to answer.

And certainly “not advising your presence due to danger” is only one of the various, and varied, solutions of the Fermi Paradox, on which I was privileged to lead a guided discussion at the very first Tennessee Valley Interstellar Workshop. (The introductory presentation for that open-forum discussion has become a fairly popular lecture on the SF convention circuit in the Southeast, especially after I expanded it a bit.) There are quite a few other solutions, as well, several of which might apply in this situation.

But we are still left with the fact that there MUST HAVE BEEN communication of SOME sort during the construction of the object, if only between builders. Communication that we have not observed, but must have done, if it happened.

Stephanie Osborn

“The Interstellar Woman of Mystery”

Dyson Sphere
Dyson spheres should be the easiest objects in the local galaxy to detect. If you think it through, you will realize that the sphere absorbs ALL of the energy released by the central star. In order to keep the sphere from simply melting down, ALL of that energy has to be released to the environment beyond the sphere. That released energy will be infrared, mainly.
Basic physics says that a Dyson sphere must be among the most IR intense objects in the galaxy, which would be easy pickings for modern astronomers.

Kevin

Jerry,
For that matter, referring to my prior post on the IR signature of a completed Dyson sphere, this mystery substance causing significant dips in light output from the F-type star should have a significant IR signature as well. This would help differentiate cometary objects from non-cometary objects orbiting that star.

It occurs to me you may not recall Zahn’s spiders
They developed an odd jump drive requiring pairs of black holes to trip the drive by passing between them
Gave very few accessible systems (as pairs of black holes being rare)
But travel was instantaneous
Rest of us developed more standard warp drive far slower but capable of star-to-star travel
They encountered a Foe that scared be jeezus out of the spiders and they devoted all racial energy into producing a Dyson sphere around and hiding their home world that looked like red giant from outside
They had to heat it to produce proper spectral lines
However Foe found them before they could complete the sphere
Hence we explain:
1) why only one sphere? Because their technology ,only gave them access to a few very scattered systems so no spheres in neighboring star systems
2 ) why build it? To hide from their enemy
3) how old? Not recent and Doesn’t matter it was damaged when foe attacked killing the project and them
4) dimming? From the holes blasted in the ,sphere as it rotates or whatever
As I said life imitating art 🙂
cdb
The Eldest Geek

: Dyson Swarm

Jerry,

Most of the popular articles on the oddly variable star KIC 8462852 are misusing the term “Dyson Sphere”, of course – a true Dyson sphere would totally enclose the star and collect all its energy, and would be visible externally only as a warm-ish infrared source. What we’re talking about here is the possibility that 8462852 is a “Dyson Swarm” – a star with enough orbiting energy-collection structures to block a significant fraction of its total output.

Not as remarkable a possibility as an actual Dyson Sphere, of course, but remarkable enough for me. The combination of variability too complex and large to be caused by a small number of planets and the apparent absence of the dust you’d expect to accompany a large number of natural-origin bodies is intriguing. I’m looking forward to the results of proposed radio-telescope surveys. I’m also hoping some bright person can take the existing Kepler data and come up with an orbiting-objects model (or models) that fits the observed variations.

Interesting times, indeed. In the good sense, in this case.

Henry