As a consequence of my dismissing human space futures as fantasy, I was contacted by an academic astrophysicist counterpart pushing back on my position—which is perfectly reasonable. But the nature of the conversation offered too many revealing insights for me to set it aside. I share the dialog here as a case study representing two extrema on the space question, quickly exposing foundational disconnects of staggering proportions in terms of how the universe works and what we might expect of the future.
The identity of my interlocutor is not revealed, here. Suffice it to say that they are an astrophysicist in a research/professorial position having an impressive list of publications to their name as well as a few books—often touching on the topic of space futures. In other words, the opinions you are about to see are from a serious professional engaged in the subject at hand—more so than I am, in fact.
Not every sentence from the thread is reproduced below (cut about 10% of material less germane to the issue), but whole sections are left intact with no editing or modified emphasis. For each of the four rounds in the exchange, I include the original verbiage, then elaborate a few points before moving to the next round. Each starts with Not Me (NM) followed by the response from me (TM).
A recurrent emerging phenomenon is one of apparent symmetry, in a number of facets. For example, a top-level assessment is that each appears to think the other’s position is bonkers, and I’m ineligible to judge.
Round 1
The initial communication included the following core piece:
NM: […] space settlement is the most certain and in the long run the ONLY mitigation for almost all existential risks human species is facing at the moment and in the near-to-medium future. Conversely, [I argue] that the prevailing space skepticism in much of the academia and the media is just another expression of cognitive and moral myopia and deep ethical irresponsibility for future generations.
TM: In a sense, my skepticism lies in what is missing rather than what is “there.” In other words, narrow focus lacking full context (anthropological, ecological, psychological, political, demographic, economic, etc.) can easily run off making unsupportable/unconstrained claims based on incomplete mental models (as all mental models are bound to be) and decontextualized extrapolation of an anomalous period. Even the technical front is basically delusional fantasy from my perspective. Maybe 0.1% of what would be needed for off-Earth living (or is it 0.01% or 0.001%?) has been actually demonstrated. I would be more easily convinced (but still orders-of-magnitude short) if someone were to demonstrate a decades-long self-supporting colony on Mt. Everest or even 10 meters below the ocean surface. But even that is essentially beyond our means despite being vastly (unimaginably) easier. It’s a bit ironic (and seemingly non-productive) to use the myopic framing, as that cuts both ways. I would call indulging in futile space fantasy the morally irresponsible path.
Round 1 Reflection
Independent of your own position, it is amusing that two diametrically opposite viewpoints can consider the other to be myopic and irresponsible. The symmetry is almost beautiful. Either view rests on some unprovable notion—or even faith/conviction—of what the future holds or could hold, so that the moral value of the same pursuit flips according to the ultimate fate. Only one will be right: time will break the symmetry.
I’m also struck by another symmetry: each of us believes the other’s position to be the prevailing view, thus self-identifying as an outcast/victim of sorts. Based on how hard it has been for me to find instances of prominent naysayers, while rhapsodies are a dime a dozen, I stick to my view. Even books whose main thrusts are criticism of the space endeavor tend to stop short of calling it fantasy that is unlikely to ever materialize. I perceive two biases at play, here: our culture does not reward pessimism; and enthusiasm makes advocates more vocal. Thus, it stands to reason that space promotion would be more prevalent in the public arena than space pessimism. We can’t both be correct, but we can both believe that we are.
Round 2
NM: I am COMPLETELY CERTAIN that at some point, about 3.2 million years ago or so, there were some among our hominin ancestors who regarded walking on two legs and not living in tree canopies as “delusional fantasy” which has 0.0…1% chance of succeeding in face of all the dangers and uncertainties facing them on the ground. As [the saying goes], I’ll drink one – but not more than one – for their souls.
TM: I find your (commonly-encountered) argument to be very thin, isolating one thing that *did* happen in hindsight (and that wasn’t technically unprecedented or hard to pull off, at that). It implies that anything we deem unlikely to transpire will become likely in the fullness of time, and that future pessimism is never justified – bypassing assessment of the actual context. People have also doubted that humans would ever fly like birds, flitting from treetop to treetop, or live in underwater caves with the eels. Millions more. All wrong? I’d say the vast majority of such speculations/musings never materialize for lots of reasons. I’m sure you could come up with a huge list of inspiring ideas that will never come to pass. And if you can’t, well, I’d say that signals a serious disconnect.
Round 2 Reflection
We hear variants of this point all the time: people 200 years ago could not possibly have foreseen… Therefore anyone who doubts any conjecture—however outlandish it might seem—is clearly a fool to do so. Such an argument is “only” logic, and not a very impressive instance, at that. Logic is just one tool for thinking, and one that can backfire, as logic alone tends to lack almost all context. This sort of “argument” is deployed as an attempt to terminate debate, using a flimsy analog to establish any pessimistic view as invalid—which strikes me as a little extreme (i.e., an overwhelming bias that can’t be correct).
Importantly, such statements work backwards, which cheats entropy’s arrow of time. Hindsight is like that, requiring no analysis to be correct, and contributing a misplaced sense of inevitability to any random future notion. We can’t just posit some desire like space habitation in the future and put it on the same footing as something that actually materialized through the billion-year gauntlet of causality. For every one that does instantiate, how many millions (or vastly more) do not?
Oh, and keep that toast to the doubting souls in mind for later.
Round 3
NM, [in response to my statement, It implies that anything we deem unlikely to transpire will become likely in the fullness of time]: Exactly! That is the idea underpinning all science and philosophy, going back to Democritus and elaborated by Aristotle as the Principle of Plenitude and many subsequent names, which all boil to one thing: everything that is not forbidden by laws of nature (incl. cosmological boundary conditions, if you wish to split hairs) WILL indeed happen. I’m kind of flabbergasted that you reject it: all modern physics is built upon it. Think of Feynman’s diagrams, for instance. Or Penrose’s singularity theorems. For me, it’s enough to consider what the opposite will mean: to say NOW that something allowed by physics will NEVER happen in 10^100 years strikes me as the extreme of hubris and egocentrism. Which kinda defeats your starting point, doesn’t it?
TM: Well, that does lay the disconnect bare, and I’ve learned that arguing against faith doesn’t often work, so I should opt out, but find it difficult to do so.
Not everything that *can* happen will, in the very finite life of the universe. Just as not everything that could happen to you will happen to you in your lifetime: a vanishingly-small number of the near-infinite possibilities will actually manifest. If sufficiently motivated, we might build a literal castle in the sky, rockets and jets and propellers ablaze. Physics doesn’t disallow. But come on. I’m sure you could go all day listing things that could happen but never will. Again, if you can’t, then try harder: imaginations can always outstrip reality, even remaining within physics.
Example: one could see it as a combinatorial bottleneck. Some legitimate sentences will never be constructed. It’s not that hard to make up one that has never appeared before, though physics won’t prevent any from being formed. Or consider a modest digital photo format with 2,000×1,500 pixels at 24-bit color. That’s 3 million to the 24th power, or 1e155, which is FAR larger than the number of atoms in the visible universe (thus forget storing even 1e-80 of them). Even generating temporary instances at one per nanosecond, only 1e28 can be created in the age of stars. Nothing in physics prevents any one of the images from manifesting (a very large number of which have you riding on the shoulders of Napoleon, wearing any number of costumes and set in any number of backdrops), but almost none of them will ever happen. I don’t consider this to be hubristic or egocentric: just staggering numbers – and as a result obvious that the vast vast vast vast majority of possibilities will never happen. To me, believing otherwise seems quantitatively unhinged.
Round 3 Reflection
Again, we appear to have encountered a symmetry of flabbergastery. In NM’s view, for every conceivable photo of them riding on Napoleon’s shoulders, whole planets are devoted to that image as a sacred visage. Wars are fought over it. Rival civilizations clash over whether a mole is on the left or right cheek (as the set of all possibilities contains a version with a mole anywhere you like, or two, or three, or an actual mammal-mole on NM’s head, or even that mole sporting a mole on its cheek). None of this is disallowed by physics, so NM says every such possibility WILL happen. And I’ve just gone down one very minuscule and specific rabbit hole around middling-resolution digital images. It’s just not that hard to mentally conjure physically-allowed scenarios that have vanishingly-small odds of occurring (let alone all possibilities happening). Even restricting oneself to the narrow domain of digital photos, it’s actually kind-of fun to explore the endless variety of possibilities among the set of 10155 images. Some are downright embarrassing, and you’ll hope those images never pop up!
Also note that NM mistakes the converse statement, suggesting that I would claim some particular event will NEVER happen. No. I would say that some events have vanishingly small probability and thus are extremely unlikely to ever happen, which is a lot different than declaring they “never” could, and outrageously shy of “always WILL.” It’s quantitative; probabilistic. The central point is that physically-allowed possibilities far outnumber what a finite universe has the opportunity to express.
By the way, as much effort as I have made to dismantle ego, human supremacy, and hubris, I have to take seriously any charge of indulging in such attitudes. Is that what I’m doing? It’s hard for me to shake the sense that faith in humans expanding into space is very self-centered and hubristic. Meanwhile, I bend over backwards to demote our importance or authority to call the shots in the universe. I’m missing something big here, apparently.
Finally, for those who are not astrophysically calibrated, 10100 years is, absurdly, 1090 times longer than the age of the universe. A star like our sun lasts about 10 billion (1010) years. Lower-mass stars can go longer, like hundreds of billions of years. Let’s be generous and multiply that by about 1,000 to get something in the ballpark of 100 trillion (1014) years for the age of stars. This already-intuition-busting duration (10,000 times the current age of the universe) is unimaginably short compared to 10100 years: 0.00[80-more-zeros]01%. Just as only so much can happen to us in our lifetimes, limited lifetimes of stars dampen the “everything goes” philosophy—divorced from practical reality as another misfire of the imagination. In fact, depending on its origin, the accelerating expansion of the universe could rip even every atom apart within a (short?) trillion years, at which point it’s definitely game-over for all those fun possibilities of the unconstrained imagination.
Round 4
NM: OK, we’ll have to agree to disagree. I don’t care about my own lifetime, in lifetime of particles which constitute me everything will happen – and even the lifetime of THIS universe is unimportant, since we have enough reasons to believe that there is a vaster multiverse out there, which is infinitely old and will continue to exist for an infinite amount of time. 1e155 is just as small as the number 1 in this wider context. I have no problem thinking in this context, since THAT requires imagination, and not thinking about allegedly unachievable things that could never be verified (logic teaches us not to try to prove negatives from our minuscule, infinitesimal experience). Hence, among other things, every planet and star in the universe will eventually be inhabited and teeming with Life: even if humans don’t do it (which would be stupid, self-defeating, parochial and boring not to do), someone else certainly (in the asymptotic sense) will.
TM: Well, if we’re willing to move the goalposts to even other universes (and who am I to doubt the possibility of a multiverse?), then my strong suspicion that humans (of Earth in this universe) will never live in space is on infinitely safer ground to which it seems one has little basis for objection (for every way it could happen, perhaps trillions of ways it won’t, all allowed by physics). And that’s my main concern as my readership and impact/scope happens to be exclusively Earth-based humans.
Your final statement veers right back into unhinged territory (confining to our finite-stellar-lifetime universe and asserting every star/planet in fact!). Is it parochial and boring that we won’t have castles in the sky, or might practical reasons enter?
Round 4 Reflection
You heard that right. It’s small-minded to differentiate 1 from 10155 when graced with sufficient imagination (more on this below). Douglas Adams would warn NM against stepping into the next crosswalk. I might recommend the casino or lottery tickets for a more joyous experience.
Lots of sins can be accommodated by taking mathematical infinities seriously. It’s heady—even rapturous—stuff to flirt with the infinite. But physics has a way of preventing literal infinities from manifesting. Certainly anything to do with the actual subject at hand (humans living off-Earth) has gone off the rails when arguments rest on numbers so vast that 1 and 10155 are rendered indistinguishable by mental gymnastics.
We now return to the statement in Round 2 about toasting a single drink to misguided souls. One might as well commit to 10155 drinks—pretty much stripping any meaning from the statement. Don’t ask the dumb liver what it thinks: what could it possibly know compared to inspirations bouncing around in our glorious crania?
We find another partial symmetry in each side’s challenges involving imagination, but in entirely different senses. My position is twofold: that humans cannot possess sufficient imagination to anticipate the tangled twists in something as complex as ecology or humanity’s future; and that imagination is anyway unconstrained to the point of being practically useless: not a suitable guide to the real world. In other words, I’m not sure imagination is an entirely complimentary attribute: more is not always better.
Discussions of this sort always leave me pondering: have they ever built anything? Being neck-deep in technology, I’ve invented and realized a number of successful devices of non-trivial sophistication. It’s all about compromising the imagined to what the universe will allow. Limits assert themselves at every turn. Imagination is required, but quickly exceeds constraints of nature and must be reigned in (humbled). Armchair theorizing (talk) is cheap—frequently sacrificing messy multi-threaded context for tidy logic. I suspect a large part of the disconnect—and blithe dismissal of hundred-plus orders-of-magnitude as meaningless—stems from this experiential estrangement from the real and uncompromising universe.
At this point, I terminated the conversation—sensing only divergence.
You Be the Judge
What we have here is two well-educated astrophysicists on extreme opposite sides of an issue, down to the fundamental interpretation of numbers and probabilities—hypothetical vs. actual. Ironically, NM appears to take Murphy’s Law literally: if something (bad?) can happen, it will. My preferred version is that if something can happen, don’t be surprised if it does (or surprised if it doesn’t, depending on the odds). Not every possibility allowed by physics has the opportunity to manifest in the finite space and time to which we (or our universe) have access. The combinatorial possibilities so vastly outnumber the actual path walked by the universe that “actual” is a vanishingly small subset of the physically-allowed. In the end, our universe only goes ONE way out of an uncountable infinitude of seemingly-possible outcomes. Imagination must take a distant back seat to actual occurrence.
Anyway, each apparently finds the other to be emitting gibberish, essentially. As a result, each probably feels reaffirmed in their position with regard to space settlement: “If this is characteristic of how the other side thinks, no wonder their conclusions seem totally unhinged.” As with so many issues, we each believe ourselves to be in the right—and I can attest to how difficult it would be to move me off my position, assuming that to be symmetric as well. What is one to do?
Granted, this conversation reflects a sample-size of one, and thus can’t be taken as representative of the entire space-enthusiast community. On the other hand, not only does it come from a credible source who is professionally engaged in this topic, but it isn’t in any way “cherry-picked” from a menu: it was the only instance of someone reaching out to challenge the space pessimism expressed in my recent blog series. I would not be surprised if the deep disconnect between me and space enthusiasts can often be distilled down to disagreement as fundamental as this one, on whether “infinity and beyond” is taken literally or contextualized within limits. It’s not news that many in our culture are violently allergic to the notion of limits (and then we all die of limitations). Maybe fear of death is another key driver for space fantasy, but let’s not get into that just now.
