Time and space, energy and society, and the mortality of species

Contents:

A fickle species, a bountiful island, and a hostile sea;       Thunkle, Thunkle, massive star;         Skimming stones on the interplanetary lake;             Something’s cooking, and a pancake flip is on the cards;       Species longevity and Star-Trek;       Interstellar?;       Off you go, toodle-pip!;       The chances of habitable destinations;       The needle in a haystack summary;       The implications for an energy transition philosophy: a budget.

A fickle species, a bountiful island, and a hostile sea.

Between the extremes of fatalistic irresponsibility and over-optimistic fantasy, there lies a middle-ground of realistic habitat stewardship.

It may sound morbid but our species won’t last forever. That’s more or less a given. 

One holiday many years ago I took my kids, who were quite young at the time, to Greenwich Planetarium. It was kind of a spontaneous thing. Having turned up there we didn’t want to disappoint the kids, but the show on offer was something along the lines of “Ten ways the world might end”. With the benefit of hindsight, probably not the best one for a child’s introduction to a planetarium – but they took it in their stride bless ‘em. 

As our young kids grimaced at the various ways their still new-to-them universe might destroy them, it was to us adults in the room, also a healthy reality check. It is very clear, there will be an end. The universe is overwhelmingly a hostile place for life, and constantly changing, often cataclysmically.

Thunkle, Thunkle, massive star

Stars evolve and expand to consume their inner systems then die with a whimper, or they explode before collapsing into mega-dense relics, and at the extreme, black hole singularities, playing with the fabric of our space time as a cat with a mouse. Stars don’t however, have to do those extreme things for the environment on their orbiting planets to change radically. Minor changes are enough to have big consequences. 

How long have we known our sun? It has seemed fairly stable over the duration of our acquaintance, to be sure, but it would be interesting to know wouldn’t it, what the biggest solar “outlier” event was in its past history that we don’t yet know about. Maybe it’s best that we don’t know.  

Then there are gamma ray bursts – linear beams of radiation occurring during supermassive star supernovae and their collapse into black holes. These are thought to occur only between once every ten thousand to a million years in any one given galaxy. Not cause for immediate alarm then you might think, especially as you have to be aligned with the beam emanating from the stellar poles to be at risk. However, when they occur they are the largest and brightest explosions in the universe, in a few seconds releasing energy at least two orders of magnitude greater than our sun will in its entire 10 billion year plus lifetime. That's why we detect them popping off in other galaxies.

If you happen to be in the beams of one of those going off in your own galaxy, you won’t be reading about it in the paper the next day. It’s one of the reasons why sitting on the edge of the galaxy - as we do - might be a better place for life to evolve. Sitting in the higher stellar density regions of the galactic centre would place us more at risk. The loungers closest to the gamma-ray pool get splashed more often.  

Skimming stones on the interplanetary lake

But if the powers both stellar and galactic are gargantuan in their ability to smite, we are all too familiar also, in our 20th and 21st century scientific literacy, of the ability of a relatively routine Mt Everest sized chunk of rock to wreak havoc on the planet. Take a read of the account by Peter Brannen in his 2017 book The End of the World: Volcanic Apocalypses, Lethal Oceans and Our Quest to Understand Earth’s Past Mass Extinctions (see inset box below). 

We may think that these impacts were features of an early solar system, but the dinosaur-doom Chixculub Crater event was relatively recent in planetary terms (within the latest 2% of our planet’s history) and was preceded by other similar ones. Rocks of this size do inhabit outer reaches of the solar system, as well as the ones we know and track better further in. Gravitational disturbances, perhaps by passing stars, or some big dark ultra-long orbit planet(s) out there which we haven’t found yet - may be periodic dark horses of apocalypse.  Hollywood likes to think we could do something if we saw one coming, and who knows, maybe, but it is far from assured.  

Even if we did get good at predicting and preparing for those ones, 2017 showed us something else that we can never really prepare for. ?Oumuamua swung in as the first confirmed interstellar object, roughly 100x1000x100 m or thereabouts, and unusually elongate. It also had poorly understood elements of apparently non-gravitational acceleration as it left the solar system – likely to have a natural explanation such as solar radiation light pressure, or comet-like outgassing (though none was detected) but enough to raise eyebrows at the time. By virtue of its average speed (just under 100000 km/hr or ~ 26km/s relative to the sun when in interstellar space) there was a very small time window to observe it and verify details of the trajectory – which at its fastest point was three times the average. By the time we knew enough about it to know where it was going, it was here, and going too fast for anything we could make to catch it up. And then it was gone.

The reasons for it apparently being so elongate are still being discussed. One suggestion is that some catastrophic planetary collision in some other part of the galaxy, flung gravitationally strung-out planetary-spaghetti into interstellar space, for who knows how long before it entered our system. That, one might hope, would be a relatively rare event. But is it? 

As of Feb 2021 we know of 4678 sizeable “exoplanets” outside our solar system and that number currently doubles about once every 2 ? years.  The furthest of those is 11000 light years away, but 95% are within 1500 light years. We are seeing an unknown percentage of the ones within that volume – probably a tiny proportion. That 3000 light year sphere compares to the circa 100000 light year diameter of the galaxy - i.e. only 3% is even beginning to be scratched. There is a lot of planetary stuff going on out there. OK, so space is huge, collisions rare, but couple it with the vastness of time, and things happen. We sit in a galactic bowling bolide alley.  

Something’s cooking, and a pancake flip is on the cards.

Then of course, we don’t need to rely on outside intervention to detect threat. From that churning furnace below, huge volcanic flood basalt provinces covering areas of anything from a hundred thousand to ten million km2 typically have a habit of bursting through the crust every 10-20 million years or so. It’s possible some, not all, might be related to bolide impacts and their antipodal effects, but it would appear mantle plumes are quite capable of generating them on their own.   These are long lived events occurring over hundreds of thousands and even millions of years, but their effect on climate and environment can only be profound.  

Violent extrusion of searing heat at the surface is not the only way the earth’s churning furnace can affect life and society though. The dynamo of molten nickel and iron in the Earth's core sustains the Earth's magnetic field, and this in turn protects us and our infrastructure from many effects of solar radiation. Without it, UV radiation and the deluge of cosmic rays is more intense, with implications for health, electronics, and the power grid. On average about every half a million years, the magnetic field in its north-south alignment, gradually weakens and emerges with the opposite polarity. This whole process probably takes about 5 000-10 000 years, though we do not know for sure, and during that time the field may weaken to very low strength, leaving life and infrastructure vulnerable and exposed. 

The good news, clearly, is that life on Earth has endured through many such reversals. The bad news is that modern society has not yet experienced one so we have little idea how well it will cope. The last flip happened just over three quarters of a million years ago. Some areas of the world's magnetic field, including the South Atlantic and South America, are showing signs of local instability and localised reversal. While such anomalies may be a quite normal feature of our very dynamic core, it is entirely possible that we are not too far off the next major flip. There will be one sometime. Species survival is likely. How society comes though it is less certain. 

Species longevity and Star Trek

All this is a rather roundabout way of saying, we aren’t around forever. Species on Earth typically last between 1 and 10 million years before something natural throws a punctuation mark at the sentence. Whatever basis we plan on, planning on being around forever isn’t a likely scenario. The caveat of course is that no species has ever left the planet before, (at least not wilfully and alive) and put its feet on another world like ours has. Maybe that is a game-changing paradigm that sets a new precedent to buck the trend of species survival rates and durations?

Well, who knows, pretending certainty about the future is a fickle game, and humanity has certainly surprised in its achievements (and cock-ups) to date. Hollywood would certainly have us imagining leaving Earth to “colonise the galaxy”, but there are vast physical and commercial hurdles that put huge barriers in the way of any such effort. It is a very real possibility that it simply isn’t practical and that we are stuck on Earth for the duration. But what a great place to be stuck.

Think about it – even if we consider Mars and Venus - it is bad enough. So many of the metals and minerals we rely on for surface ore extraction and society are a function of the plate tectonics and water circulation that affects our own earth’s crust. The fractionation and coalescing of a quartz rich continental crust is something that requires plate tectonics to have been active. Combined with the liquid water chemical processes which enrich these elements in the near surface crust, these both form an important pre-requisite for economic extraction of many elements and minerals. 

The elemental presence may exist on other large rocky planets, but the processes of solution and tectonic recycling that concentrate them on Earth are special, and not generally present elsewhere. The minerals may be present, but perhaps in vastly weaker and more distributed concentrations. Mining on other largish rocky planets - if we ever got to the place we could achieve it, for a lot of things might be vastly more unproductive than it would be here.

Much smaller asteroids derived from the cores of once much bigger bodies, might on the other hand have impressive concentrations of useful metals that in theory could be harvested, but these are not places to live.  So, any use of them involves transportation of mass in and out of space – an enormously costly exercise which somebody still has to pay for. Then to mine ore robotically in almost zero gravity in the asteroid belt and return it to where we can access it? It takes a level of robotics and space transportation that while conceivable is still some way off, but perhaps more importantly, would be hugely expensive. The costs of these metals on Earth would have to be prohibitive for it to make sense. 

Assuming hyper-optimistically it could one day be done commercially, the formidable aspects of ever colonising Venus and Mars without putting more drain on Earth’s resources to supply such colonies, would require the immensely expensive extraction of these ores from asteroids. Lifting stuff out of Earth gravity would be too hard and too costly and indigenous ores might not be up to the grade. For all the “vision” Venus and Mars are not nice places to be either. Never mind the outer reaches of the solar system. Perhaps the real focus should be beyond our solar system, as in the really hard-core sci-fi. The place where other kindlier planets just might exist?

Interstellar?

For the purposes of training our perspective on our own planet even further, let’s for completeness' sake, ask the question, can we ever contemplate, as a species, settling in another solar system? To do so given the vast distances involved involves either 1) some kind of hibernation style death-defying stasis technology whereby colonisers are awakened on discovery of a candidate site for settling or 2) some kind of “wormhole” style connection to another part of the universe whereby we bypass the constraints of sub light-speed velocity and the vast associated journey times. 

If we consider the second – we have no knowledge of such a "holey" place nearby nor any knowledge of how to make such a “fold and puncture” hole in space time. Something that would presumably involve vast amounts of energy to achieve, if it ever could be "manufactured" - which seems unlikely. Even if we did, to imagine that a species as fragile as our own could enter such a thing and emerge unscathed in some distal part of the universe – seems to have a probability that is vanishingly small. 

Even if we got that far, we somehow need to get all the equipment we require for finding a suitable site and settling on the other side of the “wormhole” to also get through unscathed. In all likelihood, such a journey isn’t going to just turn up on the doorstep of a kindly planet, so getting through to the other end of a wormhole likely still entails long epic space journeys. Given all those accumulating, multiplying, vanishingly low probabilities, it seems the former option, i.e. a hibernation style journey is the best bet.

Off you go, toodle-pip!  

However, when it comes to long controlled human stasis or hibernation, we have no capability to do this yet, nor is it “just around the corner”. There is no guarantee it is possible. Let’s for one minute assume this obstacle had been overcome. We then want to set out to colonise neighbouring regions of the Orion galactic arm. 

To do so can only involve one of two approaches – a) sending some hibernating colonising “craft” out there arbitrarily at some star systems with no a-priori knowledge of its precise final destination, or b) knowing in advance a suitable or possibly suitable destination exists and aiming for it. 

In the case of a), we somehow need to make our spacecraft smart enough to detect a nearly planet or system that is habitable, wake up the crew safely and efficiently, and we need to give it enough energy on board to avoid obstacles it detects along the way, and avoid total freeze. This for a journey of indeterminate length, perhaps millennia. We also need to be able to put the crew back into stasis and provide enough energy to escape a system again if it was all a false alarm. That stretches credulity. 

No, it seems the only way forward is to have some pre-selected candidate, observed from Earth, to send people to, before a launch. That means an army of interstellar probes being sent out to destinations that at the moment, seen from here, are stellar occlusion blips at best, and then waiting another age for probe signals to return to us. The probes would have to be smart enough to search out destination systems on their own, without direct command from Earth. The two-way communication times would simply be too long. 

That means centuries of waiting for even just the preliminary shortlist. Such probes are unlikely to luck upon all the information we need first time, and would likely be forced to zip by quickly and fleetingly at interstellar speeds like 'Oumuamoua did, so factor in at least one other fine-tuning set of probes, and another century or two before we are sure enough to depart, but still with big question marks. 

Want to hop on? It will be a one-way trip. The destination might have been evaluated only partially or incorrectly, with unforeseen complications, and it may be inhospitable. There will be no feasible plan B. No sailing back to Genoa. There will be miniscule resources for you to begin when you get there. No rescue available. No going back. No profit posted on Wall Street for the next financial year after arrival. 

So, even if with all those obstacles some of us still decide to venture forth, it’s not as if there is any realistic choice or new opportunity for those of us left back on Earth, except for a tiny, tiny, minority backed by some quintillionaires who for some reason are ready to send them off on a non-financial-return escapade into the unknown. 

The chances of habitable destinations

What actually is the chance of finding another planet that is suitable for life? The “Drake” equation famously tries to estimate the number of systems generating extra-terrestrial civilisations in our galaxy, and includes a number of habitation constraints.   It is however a hugely crude tool, and aimed at estimating what systems might evolve their own life, not those where we might be able to land a space craft first-pop and successfully subsist long enough to further new generations. In any case, the more we learn about our own planet, the more we realise just how many other things have come together for life and society to actually thrive. Some of these include:

• A galactic location facilitating low gamma ray burst vulnerability
• Temperatures to allow liquid water on the surface, it’s evaporation, and precipitation away from oceans, and a host of beneficial chemical and biological processes
• The right mix of gases [CO2, nitrogen and oxygen] in the atmosphere for plant and animal life to evolve and co-exist without runaway greenhouse effect.
• Sufficient gravity to retain atmosphere.
• Enough ocean to moderate temperature extremes.
• Absence of absurdly huge tidal forces from nearby planetary bodies.
• The right atmospheric density to burn up most meteorites.
• A dynamic fluid core to generate a magnetic field and protect from cosmic radiation.
• A stable location with a stable star in a stable star system.
• A single sizeable moon that stabilises the earth’s axial tilt and provides stable day lengths and stable seasons.
• Suitably placed massive outer planet or planets to help absorb and deflect bolides aimed at the inner solar system.
• Crustal differentiation, fractionation and the evolution of continents, to provide significant land masses emergent from any large scale oceans that do exist.
• Plate tectonics, to allow continental separations and multi-path species evolution and protection, and also to allow geological processes that enhance mineral concentration. However, we don't want things so active that earthquakes and eruptions are too frequent, blowing or shaking everything to smithereens regularly. We want goldilocks "just right" tectonism.
• A bolide frequency infrequent enough to allow species persistence.

The needle in a haystack summary

We can therefore surmise that the chances of us being able to survive in any meaningful way off Earth (excluding isolated high-expense, non-self-sustaining, Earth-dependent inner solar system research stations) - are vanishingly small for the foreseeable future, and not without a commercial business model that is trans-generational, trans-centuries, in its payback times. I’m not going to say it is impossible, but it does suggest the chances of us being almost totally Earth limited for the rest of our finite species existence are very, very strong. 

This could be it. 

Sci-Fi visions of being on the cusp of launching a trans-galactic civilisation may be essentially arrogant and practically stymied on a variety of points – physical, biological, and commercial.  

I might be wrong but look at how hard any commercialisation of the Moon has proven half a century after it was visited. Exploration of space for enhancement of our knowledge and curiosity has great merit, but as a colonial business venture, not really. The limitations of the human lifespan against those required for space travel have significant implications for the profit motive. Not in a good way.  

OK, the sense of some intelligent species survival beyond our own planet’s demise might arguably hold some strategic motive beyond profit, but as we have seen the chance of such an exercise being successful is remote and somebody still has to pay for the whole hyperbolically expensive exercise, with that vanishingly small chance of success in mind. It all seems rather unlikely. 

The implications for an energy transition philosophy: a budget

So, on the one hand, it might be tempting to shout “eat drink, and be merry, for tomorrow we die” and in such wanton fatalism, use resources as we see fit day to day with carefree abandon. 

However, though our species is doomed to a finiteness in time, in a manner that is nigh on inevitable, there is a truly remarkable sub-plot to the cataclysm-strewn universe we have described. This is the simultaneous ability of life to persist through it all in some form for 3.8 billion years, and for individual species to have lifetimes - even without self-conscious intelligence - of many millions of years.  We still may therefore, have a very long time to go. It might not be a story of in-perpetuity galactic conquest, but there may be yet eons left to make the most of what we have got. What we have got, is Earth.  

Philosophically too, even if we could colonise other systems, what “right” would we have to do so if we cannot diligently manage the energy budgets for our own. Given the amounts of raw energy that persist around us, if we cannot make it work with what we’ve got, surely no amount of extra-terrestrial or extra-solar system resource would make a difference. 

This article may be a very long-winded exercise to make a single point, but really, it is simply this. Our "base-case scenario" really has to be that Earth is going to be the only place that sustains our species for its duration. That means that boundless ambitions of ever-increasing expansion and boundless resource plundering from ever-increasing supplies of other planets, to gratify our energy habits, should be confined to Hollywood story-boards for any practical commercial purposes.

That in turn means we cannot absolve ourselves of a responsibility to make this planet work as best we can. To budget our energy. If we are spending energy too fast for our income, then to stop. Not to go rushing off into space in search of another overdraft facility.

Not because we are going to reside as a species on this planet forever – we won’t. One day our residence here will come to an end. Yet to make the best of the time we have here both as a species, and as individuals, responsible caretaking is required, however difficult that may be. Not because we have some inter-galactic destiny we have to fulfil in the future, Star-Trek like, living perpetually long and prospering, but rather more humbly and simply to make the best of however many tomorrows we and our descendants and accompanying species may have, until that fateful day when the universe deals us the surprise we hadn’t seen coming.