Frequently I look up at the night sky and ponder about so many things that I cannot understand. I wish I did but it is far too late now. But that doesn’t stop me from reading about the science and more. Here is a perfect example of that and I am delighted to be able to share it with you.
ooOOoo
Most normal matter in the universe isn’t found in planets, stars or galaxies – an astronomer explains where it’s distributed
Mysterious blasts of radio waves from across the universe called fast radio bursts help astronomers catalog matter. ESO/M. Kornmesser, CC BY-SA
If you look across space with a telescope, you’ll see countless galaxies, most of which host large central black holes, billions of stars and their attendant planets. The universe teems with huge, spectacular objects, and it might seem like these massive objects should hold most of the universe’s matter.
But the Big Bang theory predicts that about 5% of the universe’s contents should be atoms made of protons, neutrons and electrons. Most of those atoms cannot be found in stars and galaxies – a discrepancy that has puzzled astronomers.
If not in visible stars and galaxies, the most likely hiding place for the matter is in the dark space between galaxies. While space is often referred to as a vacuum, it isn’t completely empty. Individual particles and atoms are dispersed throughout the space between stars and galaxies, forming a dark, filamentary network called the “cosmic web.”
Throughout my career as an astronomer, I’ve studied this cosmic web, and I know how difficult it is to account for the matter spread throughout space.
In a study published in June 2025, a team of scientists used a unique radio technique to complete the census of normal matter in the universe.
The census of normal matter
The most obvious place to look for normal matter is in the form of stars. Gravity gathers stars together into galaxies, and astronomers can count galaxies throughout the observable universe.
The census comes to several hundred billion galaxies, each made of several hundred billion stars. The numbers are uncertain because many stars lurk outside of galaxies. That’s an estimated 1023 stars in the universe, or hundreds of times more than the number of sand grains on all of Earth’s beaches. There are an estimated 1082 atoms in the universe.
However, this prodigious number falls far short of accounting for all the matter predicted by the Big Bang. Careful accounting indicates that stars contain only 0.5% of the matter in the universe. Ten times more atoms are presumably floating freely in space. Just 0.03% of the matter is elements other than hydrogen and helium, including carbon and all the building blocks of life.
Looking between galaxies
The intergalactic medium – the space between galaxies – is near-total vacuum, with a density of one atom per cubic meter, or one atom every 35 cubic feet. That’s less than a billionth of a billionth of the density of air on Earth. Even at this very low density, this diffuse medium adds up to a lot of matter, given the enormous, 92-billion-light-year diameter of the universe.
The intergalactic medium is very hot, with a temperature of millions of degrees. That makes it difficult to observe except with X-ray telescopes, since very hot gas radiates out through the universe at very short X-ray wavelengths. X-ray telescopes have limited sensitivity because they are smaller than most optical telescopes.
Deploying a new tool
Astronomers recently used a new tool to solve this missing matter problem. Fast radio bursts are intense blasts of radio waves that can put out as much energy in a millisecond as the Sun puts out in three days. First discovered in 2007, scientists found that the bursts are caused by compact stellar remnants in distant galaxies. Their energy peters out as the bursts travel through space, and by the time that energy reaches the Earth, it is a thousand times weaker than a mobile phone signal would be if emitted on the Moon, then detected on Earth.
Research from early 2025 suggests the source of the bursts is the highly magnetic region around an ultra-compact neutron star. Neutron stars are incredibly dense remnants of massive stars that have collapsed under their own gravity after a supernova explosion. The particular type of neutron star that emits radio bursts is called a magnetar, with a magnetic field a thousand trillion times stronger than the Earth’s.
A magnetar is a rare type of neutron star with an extremely strong magnetic field. ESO/L. Calçada, CC BY-ND
Even though astronomers don’t fully understand fast radio bursts, they can use them to probe the spaces between galaxies. As the bursts travel through space, interactions with electrons in the hot intergalactic gas preferentially slow down longer wavelengths. The radio signal is spread out, analogous to the way a prism turns sunlight into a rainbow. Astronomers use the amount of spreading to calculate how much gas the burst has passed through on its way to Earth.
Puzzle solved
In the new study, published in June 2025, a team of astronomers from Caltech and the Harvard Center for Astrophysics studied 69 fast radio bursts using an array of 110 radio telescopes in California. The team found that 76% of the universe’s normal matter lies in the space between galaxies, with another 15% in galaxy halos – the area surrounding the visible stars in a galaxy – and the remaining 9% in stars and cold gas within galaxies.
The complete accounting of normal matter in the universe provides a strong affirmation of the Big Bang theory. The theory predicts the abundance of normal matter formed in the first few minutes of the universe, so by recovering the predicted 5%, the theory passes a critical test.
Several thousand fast radio bursts have already been observed, and an upcoming array of radio telescopes will likely increase the discovery rate to 10,000 per year. Such a large sample will let fast radio bursts become powerful tools for cosmology. Cosmology is the study of the size, shape and evolution of the universe. Radio bursts could go beyond counting atoms to mapping the three-dimensional structure of the cosmic web.
Pie chart of the universe
Scientists may now have the complete picture of where normal matter is distributed, but most of the universe is still made up of stuff they don’t fully understand.
The most abundant ingredients in the universe are dark matter and dark energy, both of which are poorly understood. Dark energy is causing the accelerating expansion of the universe, and dark matter is the invisible glue that holds galaxies and the universe together.
Dark matter is probably a previously unstudied type of fundamental particle that is not part of the standard model of particle physics. Physicists haven’t been able to detect this novel particle yet, but we know it exists because, according to general relativity, mass bends light, and far more gravitational lensing is seen than can be explained by visible matter. With gravitational lensing, a cluster of galaxies bends and magnifies light in a way that’s analogous to an optical lens. Dark matter outweighs conventional matter by more than a factor of five.
One mystery may be solved, but a larger mystery remains. While dark matter is still enigmatic, we now know a lot about the normal atoms making up us as humans, and the world around us.
The details are incredible. Take for example that three-quarters of the matter out there is found outside the galaxies. Or that there are more stars in the universe than all of the sand grains on Planet Earth.
Like so many people, I am fascinated by the universe. Just our own universe is staggering. Here are some items published on the NASA website.
Solar System Facts
Our solar system includes the Sun, eight planets, five officially named dwarf planets, hundreds of moons, and thousands of asteroids and comets.
Our solar system is located in the Milky Way, a barred spiral galaxy with two major arms, and two minor arms. Our Sun is in a small, partial arm of the Milky Way called the Orion Arm, or Orion Spur, between the Sagittarius and Perseus arms. Our solar system orbits the center of the galaxy at about 515,000 mph (828,000 kph). It takes about 230 million years to complete one orbit around the galactic center.
Now to the centre of our universe. And it give me pleasure to republish this account.
Published in 1915, and already widely accepted worldwide by physicists and mathematicians, the theory assumed the universe was static – unchanging, unmoving and immutable. In short, Einstein believed the size and shape of the universe today was, more or less, the same size and shape it had always been.
But when astronomers looked into the night sky at faraway galaxies with powerful telescopes, they saw hints the universe was anything but that. These new observations suggested the opposite – that it was, instead, expanding.
Scientists soon realized Einstein’s theory didn’t actually say the universe had to be static; the theory could support an expanding universe as well. Indeed, by using the same mathematical tools provided by Einstein’s theory, scientists created new models that showed the universe was, in fact, dynamic and evolving.
I’ve spent decades trying to understand general relativity, including in my current job as a physics professor teaching courses on the subject. I know wrapping your head around the idea of an ever-expanding universe can feel daunting – and part of the challenge is overriding your natural intuition about how things work. For instance, it’s hard to imagine something as big as the universe not having a center at all, but physics says that’s the reality.
The universe gets bigger every day.
The space between galaxies
First, let’s define what’s meant by “expansion.” On Earth, “expanding” means something is getting bigger. And in regard to the universe, that’s true, sort of. Expansion might also mean “everything is getting farther from us,” which is also true with regard to the universe. Point a telescope at distant galaxies and they all do appear to be moving away from us.
What’s more, the farther away they are, the faster they appear to be moving. Those galaxies also seem to be moving away from each other. So it’s more accurate to say that everything in the universe is getting farther away from everything else, all at once.
This idea is subtle but critical. It’s easy to think about the creation of the universe like exploding fireworks: Start with a big bang, and then all the galaxies in the universe fly out in all directions from some central point.
But that analogy isn’t correct. Not only does it falsely imply that the expansion of the universe started from a single spot, which it didn’t, but it also suggests that the galaxies are the things that are moving, which isn’t entirely accurate.
It’s not so much the galaxies that are moving away from each other – it’s the space between galaxies, the fabric of the universe itself, that’s ever-expanding as time goes on. In other words, it’s not really the galaxies themselves that are moving through the universe; it’s more that the universe itself is carrying them farther away as it expands.
A common analogy is to imagine sticking some dots on the surface of a balloon. As you blow air into the balloon, it expands. Because the dots are stuck on the surface of the balloon, they get farther apart. Though they may appear to move, the dots actually stay exactly where you put them, and the distance between them gets bigger simply by virtue of the balloon’s expansion.
Now think of the dots as galaxies and the balloon as the fabric of the universe, and you begin to get the picture.
Unfortunately, while this analogy is a good start, it doesn’t get the details quite right either.
The 4th dimension
Important to any analogy is an understanding of its limitations. Some flaws are obvious: A balloon is small enough to fit in your hand – not so the universe. Another flaw is more subtle. The balloon has two parts: its latex surface and its air-filled interior.
These two parts of the balloon are described differently in the language of mathematics. The balloon’s surface is two-dimensional. If you were walking around on it, you could move forward, backward, left, or right, but you couldn’t move up or down without leaving the surface.
Now it might sound like we’re naming four directions here – forward, backward, left and right – but those are just movements along two basic paths: side to side and front to back. That’s what makes the surface two-dimensional – length and width.
The inside of the balloon, on the other hand, is three-dimensional, so you’d be able to move freely in any direction, including up or down – length, width and height.
This is where the confusion lies. The thing we think of as the “center” of the balloon is a point somewhere in its interior, in the air-filled space beneath the surface.
But in this analogy, the universe is more like the latex surface of the balloon. The balloon’s air-filled interior has no counterpart in our universe, so we can’t use that part of the analogy – only the surface matters.
So asking, “Where’s the center of the universe?” is somewhat like asking, “Where’s the center of the balloon’s surface?” There simply isn’t one. You could travel along the surface of the balloon in any direction, for as long as you like, and you’d never once reach a place you could call its center because you’d never actually leave the surface.
In the same way, you could travel in any direction in the universe and would never find its center because, much like the surface of the balloon, it simply doesn’t have one.
Part of the reason this can be so challenging to comprehend is because of the way the universe is described in the language of mathematics. The surface of the balloon has two dimensions, and the balloon’s interior has three, but the universe exists in four dimensions. Because it’s not just about how things move in space, but how they move in time.
Our brains are wired to think about space and time separately. But in the universe, they’re interwoven into a single fabric, called “space-time.” That unification changes the way the universe works relative to what our intuition expects.
And this explanation doesn’t even begin to answer the question of how something can be expanding indefinitely – scientists are still trying to puzzle out what powers this expansion.
So in asking about the center of the universe, we’re confronting the limits of our intuition. The answer we find – everything, expanding everywhere, all at once – is a glimpse of just how strange and beautiful our universe is.
For the first day of September I wanted to change the topic to an item that was recently published by The Conversation.
Space has always been fascinating to me. One of my enduring memories was standing on the roof of my Land Rover in 1969 during a long journey around the interior of Australia. We were in the Nullabor desert and it was flat, and lonely, for miles and miles. This particular night I clambered up onto the roof and just took in the night sky. There was not a single spot of human-caused light pollution and the night sky was beautiful beyond words.
Later on when I was sailing I used to regard the North Star as my friend.
What is beyond outer space? – Siah, age 11, Fremont, California
Right above you is the sky – or as scientists would call it, the atmosphere. It extends about 20 miles (32 kilometers) above the Earth. Floating around the atmosphere is a mixture of molecules – tiny bits of air so small you take in billions of them every time you breathe.
Above the atmosphere is space. It’s called that because it has far fewer molecules, with lots of empty space between them.
Have you ever wondered what it would be like to travel to outer space – and then keep going? What would you find? Scientists like me are able to explain a lot of what you’d see. But there are some things we don’t know yet, like whether space just goes on forever.
Planets, stars and galaxies
At the beginning of your trip through space, you might recognize some of the sights. The Earth is part of a group of planets that all orbit the Sun – with some orbiting asteroids and comets mixed in, too.
You might know that the Sun is actually just an average star, and looks bigger and brighter than the other stars only because it is closer. To get to the next nearest star, you would have to travel through trillions of miles of space. If you could ride on the fastest space probe NASA has ever made, it would still take you thousands of years to get there.
If stars are like houses, then galaxies are like cities full of houses. Scientists estimate there are 100 billion stars in Earth’s galaxy. If you could zoom out, way beyond Earth’s galaxy, those 100 billion stars would blend together – the way lights of city buildings do when viewed from an airplane.
If you could watch for long enough, over millions of years, it would look like new space is gradually being added between all the galaxies. You can visualize this by imagining tiny dots on a deflated balloon and then thinking about blowing it up. The dots would keep moving farther apart, just like the galaxies are.
Is there an end?
If you could keep going out, as far as you wanted, would you just keep passing by galaxies forever? Are there an infinite number of galaxies in every direction? Or does the whole thing eventually end? And if it does end, what does it end with?
These are questions scientists don’t have definite answers to yet. Many think it’s likely you would just keep passing galaxies in every direction, forever. In that case, the universe would be infinite, with no end.
Some scientists think it’s possible the universe might eventually wrap back around on itself – so if you could just keep going out, you would someday come back around to where you started, from the other direction.
One way to think about this is to picture a globe, and imagine that you are a creature that can move only on the surface. If you start walking any direction, east for example, and just keep going, eventually you would come back to where you began. If this were the case for the universe, it would mean it is not infinitely big – although it would still be bigger than you can imagine.
In either case, you could never get to the end of the universe or space. Scientists now consider it unlikely the universe has an end – a region where the galaxies stop or where there would be a barrier of some kind marking the end of space.
But nobody knows for sure. How to answer this question will need to be figured out by a future scientist.
A deeply fascinating essay from an individual at the University of Oxford.
I have long read the daily output from The Conversation. It’s a very useful way of keeping one’s brain cells functioning in some sort of fashion.
Yesterday morning I read an essay put out by Thomas Moynihan, a PhD Candidate at the University of Oxford.
It was fascinating and I am republishing it here.
Now it’s not for everyone. It is also long and it also has a number of videos to watch. And there’s not a dog mentioned!
But if you are interested in where we, as in human beings, are ‘going’, so to speak, then this is for you.
And I’m ready to admit that it may be an age thing; something that is of much interest to me because I shall be 75 in November and one naturally wonders about the end of life. Both individually and of society!
ooOOoo
The end of the world: a history of how a silent cosmos led humans to fear the worst.
It is 1950 and a group of scientists are walking to lunch against the majestic backdrop of the Rocky Mountains. They are about to have a conversation that will become scientific legend. The scientists are at the Los Alamos Ranch School, the site for the Manhattan Project, where each of the group has lately played their part in ushering in the atomic age.
They are laughing about a recent cartoon in the New Yorker offering an unlikely explanation for a slew of missing public trash cans across New York City. The cartoon had depicted “little green men” (complete with antenna and guileless smiles) having stolen the bins, assiduously unloading them from their flying saucer.
By the time the party of nuclear scientists sits down to lunch, within the mess hall of a grand log cabin, one of their number turns the conversation to matters more serious. “Where, then, is everybody?”, he asks. They all know that he is talking – sincerely – about extraterrestrials.
The question, which was posed by Enrico Fermi and is now known as Fermi’s Paradox, has chilling implications.
Bin-stealing UFOs notwithstanding, humanity still hasn’t found any evidence of intelligent activity among the stars. Not a single feat of “astro-engineering”, no visible superstructures, not one space-faring empire, not even a radio transmission. It has beenargued that the eerie silence from the sky above may well tell us something ominous about the future course of our own civilisation.
Such fears are ramping up. Last year, the astrophysicist Adam Frank implored an audience at Google that we see climate change – and the newly baptised geological age of the Anthropocene – against this cosmological backdrop. The Anthropocene refers to the effects of humanity’s energy-intensive activities upon Earth. Could it be that we do not see evidence of space-faring galactic civilisations because, due to resource exhaustion and subsequent climate collapse, none of them ever get that far? If so, why should we be any different?
A few months after Frank’s talk, in October 2018, the Intergovernmental Panel on Climate Change’s update on global warming caused a stir. It predicted a sombre future if we do not decarbonise. And in May, amid Extinction Rebellion’s protests, a new climate report upped the ante, warning: “Human life on earth may be on the way to extinction.”
Meanwhile, NASA has been publishing press releases about an asteroid set to hit New York within a month. This is, of course, a dress rehearsal: part of a “stress test” designed to simulate responses to such a catastrophe. NASA is obviously fairly worried by the prospect of such a disaster event – such simulations are costly.
Space tech Elon Musk has also been relaying his fears about artificial intelligence to YouTube audiences of tens of millions. He and others worry that the ability for AI systems to rewrite and self-improve themselves may trigger a sudden runaway process, or “intelligence explosion”, that will leave us far behind – an artificial superintelligence need not even be intentionally malicious in order to accidentally wipe us out.
In 2015, Musk donated to Oxford’s Future of Humanity Institute, headed up by transhumanist Nick Bostrom. Nestled within the university’s medieval spires, Bostrom’s institute scrutinises the long-term fate of humanity and the perils we face at a truly cosmic scale, examining the risks of things such as climate, asteroids and AI. It also looks into less well-publicised issues. Universe destroying physics experiments, gamma-ray bursts, planet-consuming nanotechnology and exploding supernovae have all come under its gaze.
So it would seem that humanity is becoming more and more concerned with portents of human extinction. As a global community, we are increasingly conversant with increasingly severe futures. Something is in the air.
But this tendency is not actually exclusive to the post-atomic age: our growing concern about extinction has a history. We have been becoming more and more worried for our future for quite some time now. My PhD research tells the story of how this began. No one has yet told this story, yet I feel it is an important one for our present moment.
I wanted to find out how current projects, such as the Future of Humanity Institute, emerge as offshoots and continuations of an ongoing project of “enlightenment” that we first set ourselves over two centuries ago. Recalling how we first came to care for our future helps reaffirm why we should continue to care today.
Extinction, 200 years ago
In 1816, something was also in the air. It was a 100-megaton sulfate aerosol layer. Girdling the planet, it was made up of material thrown into the stratosphere by the eruption of Mount Tambora, in Indonesia, the previous year. It was one of the biggest volcanic eruptions since civilisation emerged during the Holocene.
Mount Tambora’s crater. Wikimedia Commons/NASA
Almost blotting out the sun, Tambora’s fallout caused a global cascade of harvest collapse, mass famine, cholera outbreak and geopolitical instability. And it also provoked the first popular fictional depictions of human extinction. These came from a troupe of writers including Lord Byron, Mary Shelley and Percy Shelley.
The group had been holidaying together in Switzerland when titanic thunderstorms, caused by Tambora’s climate perturbations, trapped them inside their villa. Here they discussed humanity’s long-term prospects.
Clearly inspired by these conversations and by 1816’s hellish weather, Byron immediately set to work on a poem entitled “Darkness”. It imagines what would happen if our sun died:
I had a dream, which was not all a dream
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space
Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air
Detailing the ensuing sterilisation of our biosphere, it caused a stir. And almost 150 years later, against the backdrop of escalating Cold War tensions, the Bulletin for Atomic Scientists again called upon Byron’s poem to illustrate the severity of nuclear winter.
Two years later, Mary Shelley’s Frankenstein (perhaps the first book on synthetic biology) refers to the potential for the lab-born monster to outbreed and exterminate Homo sapiens as a competing species. By 1826, Mary went on to publish The Last Man. This was the first full-length novel on human extinction, depicted here at the hands of pandemic pathogen.
Boris Karloff plays Frankenstein’s monster, 1935. Wikimedia Commons
Beyond these speculative fictions, other writers and thinkers had already discussed such threats. Samuel Taylor Coleridge, in 1811, daydreamed in his private notebooks about our planet being “scorched by a close comet and still rolling on – cities men-less, channels riverless, five mile deep”. In 1798, Mary Shelley’s father, the political thinker William Godwin, queried whether our species would “continue forever”?
While just a few years earlier, Immanuel Kant had pessimistically proclaimed that global peace may be achieved “only in the vast graveyard of the human race”. He would, soon after, worry about a descendent offshoot of humanity becoming more intelligent and pushing us aside.
Earlier still, in 1754, philosopher David Hume had declared that “man, equally with every animal and vegetable, will partake” in extinction. Godwin noted that “some of the profoundest enquirers” had lately become concerned with “the extinction of our species”.
In 1816, against the backdrop of Tambora’s glowering skies, a newspaper article drew attention to this growing murmur. It listed numerous extinction threats. From global refrigeration to rising oceans to planetary conflagration, it spotlighted the new scientific concern for human extinction. The “probability of such a disaster is daily increasing”, the article glibly noted. Not without chagrin, it closed by stating: “Here, then, is a very rational end of the world!”
So if people first started worrying about human extinction in the 18th century, where was the notion beforehand? There is enough apocalypse in scripture to last until judgement day, surely. But extinction has nothing to do with apocalypse. The two ideas are utterly different, even contradictory.
For a start, apocalyptic prophecies are designed to reveal the ultimate moral meaning of things. It’s in the name: apocalypse means revelation. Extinction, by direct contrast, reveals precisely nothing and this is because it instead predicts the end of meaning and morality itself – if there are no humans, there is nothing humanly meaningful left.
And this is precisely why extinction matters. Judgement day allows us to feel comfortable knowing that, in the end, the universe is ultimately in tune with what we call “justice”. Nothing was ever truly at stake. On the other hand, extinction alerts us to the fact that everything we hold dear has always been in jeopardy. In other words, everything is at stake.
Extinction was not much discussed before 1700 due to a background assumption, widespread prior to the Enlightenment, that it is the nature of the cosmos to be as full as moral value and worth as is possible. This, in turn, led people to assume that all other planets are populated with “living and thinking beings” exactly like us.
Although it only became a truly widely accepted fact after Copernicus and Kepler in the 16th and 17th centuries, the idea of plural worlds certainly dates back to antiquity, with intellectuals from Epicurus to Nicholas of Cusa proposing them to be inhabited with lifeforms similar to our own. And, in a cosmos that is infinitely populated with humanoid beings, such beings – and their values – can never fully go extinct.
Star cluster Messier 13 in Hercules, 1877. Wikimedia Commons
In the 1660s, Galileo confidently declared that an entirely uninhabited or unpopulated world is “naturally impossible” on account of it being “morally unjustifiable”. Gottfried Leibniz later pronounced that there simply cannot be anything entirely “fallow, sterile, or dead in the universe”.
Along the same lines, the trailblazing scientist Edmond Halley (after whom the famous comet is named) reasoned in 1753 that the interior of our planet must likewise be “inhabited”. It would be “unjust” for any part of nature to be left “unoccupied” by moral beings, he argued.
Around the same time Halley provided the first theory on a “mass extinction event”. He speculated that comets had previously wiped out entire “worlds” of species. Nonetheless, he also maintained that, after each previous cataclysm “human civilisation had reliably re-emerged”. And it would do so again. Only this, he said could make such an event morally justifiable.
Later, in the 1760s, the philosopher Denis Diderot was attending a dinner party when he was asked whether humans would go extinct. He answered “yes”, but immediately qualified this by saying that after several millions of years the “biped animal who carries the name man” would inevitably re-evolve.
This is what the contemporary planetary scientist Charles Lineweaver identifies as the “Planet of the Apes Hypothesis”. This refers to the misguided presumption that “human-like intelligence” is a recurrent feature of cosmic evolution: that alien biospheres will reliably produce beings like us. This is what is behind the wrong-headed assumption that, should we be wiped out today, something like us will inevitably return tomorrow.
Back in Diderot’s time, this assumption was pretty much the only game in town. It was why one British astronomer wrote, in 1750, that the destruction of our planet would matter as little as “Birth-Days or Mortalities” do down on Earth.
This was typical thinking at the time. Within the prevailing worldview of eternally returning humanoids throughout an infinitely populated universe, there was simply no pressure or need to care for the future. Human extinction simply couldn’t matter. It was trivialised to the point of being unthinkable.
For the same reasons, the idea of the “future” was also missing. People simply didn’t care about it in the way we do now. Without the urgency of a future riddled with risk, there was no motivation to be interested in it, let alone attempt to predict and preempt it.
It was the dismantling of such dogmas, beginning in the 1700s and ramping up in the 1800s, that set the stage for the enunciation of Fermi’s Paradox in the 1900s and leads to our growing appreciation for our cosmic precariousness today.
But then we realised the skies are silent
In order to truly care about our mutable position down here, we first had to notice that the cosmic skies above us are crushingly silent. Slowly at first, though soon after gaining momentum, this realisation began to take hold around the same time that Diderot had his dinner party.
One of the first examples of a different mode of thinking I’ve found is from 1750, when the French polymath Claude-Nicholas Le Cat wrote a history of the earth. Like Halley, he posited the now familiar cycles of “ruin and renovation”. Unlike Halley, he was conspicuously unclear as to whether humans would return after the next cataclysm. A shocked reviewer picked up on this, demanding to know whether “Earth shall be re-peopled with new inhabitants”. In reply, the author facetiously asserted that our fossil remains would “gratify the curiosity of the new inhabitants of the new world, if there be any”. The cycle of eternally returning humanoids was unwinding.
In line with this, the French encyclopaedist Baron d’Holbach ridiculed the “conjecture that other planets, like our own, are inhabited by beings resembling ourselves”. He noted that precisely this dogma – and the related belief that the cosmos is inherently full of moral value – had long obstructed appreciation that the human species could permanently “disappear” from existence. By 1830, the German philosopher F W J Schelling declared it utterly naive to go on presuming “that humanoid beings are found everywhere and are the ultimate end”.
Figures illustrating articles on astronomy, from the 1728 Cyclopaedia. Wikimedia Commons
And so, where Galileo had once spurned the idea of a dead world, the German astronomer Wilhelm Olbers proposed in 1802 that the Mars-Jupiter asteroid belt in fact constitutes the ruins of a shattered planet. Troubled by this, Godwin noted that this would mean that the creator had allowed part of “his creation” to become irremediably “unoccupied”. But scientists were soon computing the precise explosive force needed to crack a planet – assigning cold numbers where moral intuitions once prevailed. Olbers calculated a precise timeframe within which to expect such an event befalling Earth. Poets began writing of “bursten worlds”.
The cosmic fragility of life was becoming undeniable. If Earth happened to drift away from the sun, one 1780s Parisian diarist imagined that interstellar coldness would “annihilate the human race, and the earth rambling in the void space, would exhibit a barren, depopulated aspect”. Soon after, the Italian pessimist Giacomo Leopardi envisioned the same scenario. He said that, shorn of the sun’s radiance, humanity would “all die in the dark, frozen like pieces of rock crystal”.
Galileo’s inorganic world was now a chilling possibility. Life, finally, had become cosmically delicate. Ironically, this appreciation came not from scouring the skies above but from probing the ground below. Early geologists, during the later 1700s, realised that Earth has its own history and that organic life has not always been part of it. Biology hasn’t even been a permanent fixture down here on Earth – why should it be one elsewhere? Coupled with growing scientific proof that many species had previously become extinct, this slowly transformed our view of the cosmological position of life as the 19th century dawned.
Copper engraving of a pterodactyl fossil discovered by the Italian scientist Cosimo Alessandro Collini in 1784. Wikimedia Commons
Seeing death in the stars
And so, where people like Diderot looked up into the cosmos in the 1750s and saw a teeming petri dish of humanoids, writers such as Thomas de Quincey were, by 1854, gazing upon the Orion nebula and reporting that they saw only a gigantic inorganic “skull” and its lightyear-long rictus grin.
The astronomer William Herschel had, already in 1814, realised that looking out into the galaxy one is looking into a “kind of chronometer”. Fermi would spell it out a century after de Quincey, but people were already intuiting the basic notion: looking out into dead space, we may just be looking into our own future.
People were becoming aware that the appearance of intelligent activity on Earth should not be taken for granted. They began to see that it is something distinct – something that stands out against the silent depths of space. Only through realising that what we consider valuable is not the cosmological baseline did we come to grasp that such values are not necessarily part of the natural world. Realising this was also realising that they are entirely our own responsibility. And this, in turn, summoned us to the modern projects of prediction, preemption and strategising. It is how we came to care about our future.
As soon as people first started discussing human extinction, possible preventative measures were suggested. Bostrom now refers to this as “macrostrategy”. However, as early as the 1720s, the French diplomat Benoît de Maillet was suggesting gigantic feats of geoengineering that could be leveraged to buffer against climate collapse. The notion of humanity as a geological force has been around ever since we started thinking about the long-term – it is only recently that scientists have accepted this and given it a name: “Anthropocene”.
Will technology save us?
It wasn’t long before authors began conjuring up highly technologically advanced futures aimed at protecting against existential threat. The eccentric Russian futurologist Vladimir Odoevskii, writing in the 1830s and 1840s, imagined humanity engineering the global climate and installing gigantic machines to “repulse” comets and other threats, for example. Yet Odoevskii was also keenly aware that with self-responsibility comes risk: the risk of abortive failure. Accordingly, he was also the very first author to propose the possibility that humanity might destroy itself with its own technology.
Acknowledgement of this plausibility, however, is not necessarily an invitation to despair. And it remains so. It simply demonstrates appreciation of the fact that, ever since we realised that the universe is not teeming with humans, we have come to appreciate that the fate of humanity lies in our hands. We may yet prove unfit for this task, but – then as now – we cannot rest assured believing that humans, or something like us, will inevitably reappear – here or elsewhere.
Beginning in the late 1700s, appreciation of this has snowballed into our ongoing tendency to be swept up by concern for the deep future. Current initiatives, such as Bostrom’s Future of Humanity Institute, can be seen as emerging from this broad and edifying historical sweep. From ongoing demands for climate justice to dreams of space colonisation, all are continuations and offshoots of a tenacious task that we first began to set for ourselves two centuries ago during the Enlightenment when we first realised that, in an otherwise silent universe, we are responsible for the entire fate of human value.
It may be solemn, but becoming concerned for humanity’s extinction is nothing other than realising one’s obligation to strive for unceasing self-betterment. Indeed, ever since the Enlightenment, we have progressively realised that we must think and act ever better because, should we not, we may never think or act again. And that seems – to me at least – like a very rational end of the world.
ooOOoo
I hope you have read it all. There’s much to engage one. And the message to me is very clear: We have to regard this race, correction: our race, as unique. As is put in the penultimate paragraph:
“Enlightenment when we first realised that, in an otherwise silent universe, we are responsible for the entire fate of human value.”
Now there’s a thought for an atheist on a Saturday morning!
Learning from Dogs 