Life, Space and the Cosmos
From Mars to the Multiverse – legendary astronomer Lord Martin Rees gazes deep into tomorrow’s worlds
Unmanned spacecraft have visited the other planets of our Solar System (and some of their moons), beaming back pictures of varied and distinctive worlds — but none propitious for life. But prospects are far more interesting when we extend our gaze to other stars: Most stars are, like our Sun, orbited by retinues of planets. Our home Galaxy contains a billion planets like the Earth. Will post-humans one day visit some of them? Or are they inhabited already? If so, are the ‘aliens’ organic or ‘AI’?
Moreover, our Galaxy is one of billions visible with a large telescope which are all the aftermath of a cosmic ‘big bang’ 13.8 billion years ago. More astonishing still, ‘our’ big bang may not have been the only one, but merely a member of a vast (perhaps infinite) ensemble.
Lord Martin Rees, one of the world’s most eminent astronomers, is a key thinker on the future of humanity in the cosmos. Martin is an emeritus professor of cosmology and astrophysics at the University of Cambridge and the UK’s Astronomer Royal and setup the Centre for the Study of Existential Risks (CSER), based in Cambridge.
Author of more than 500 research papers on cosmological topics ranging from black holes to quantum physics to the Big Bang, Rees came to Second Home to discuss his vision of the future.
“Astronomy is one of the older sciences, probably the oldest apart from medicine, the first to do more good than harm, I suspect. And it’s also an environmental science, because we’ve all looked up at the sky and wondered about it.
The first person who made it really scientific I suppose, was Isaac Newton, who was the best student we ever had at Trinity College Cambridge where I work — it’s been downhill all the way in terms of the quality of Trinity College since then, although we’ve had some quite good people since. He must have thought about space travel.
In his book Principia it shows cannonballs being fired from a mountaintop, and if they are fired fast enough then the trajectory curves downwards no more steeply than the Earth curves away underneath it. He calculated that it has to go at 18,000mph to go into orbit, far beyond, of course, what the canon of his time could do. And it wasn’t until 1957 that the Soviet Sputnik went up, followed by a few dogs, followed then by the first man in space, Gagarin, and followed eight years after that by the Apollo astronauts.
This was all a long time ago, before most people here were born. You’ve got to be middle-aged to remember when men walked on the moon — it was fuelled by superpower rivalry and there was no incentive. Had the momentum been continued, there would’ve been footprints on Mars far before today. But of course, since that time many have orbited the Earth in low orbit, hundreds in the international space station.
“When men walked on the moon, it was fuelled by superpower rivalry and there was no incentive. Had the momentum been continued, there would’ve been footprints on Mars far before today.”
But space technology proceeded apace, we depend on it every day for satnav communications and environmental monitoring. And for science it has been crucial, telescopes in space and close-up probes of the varied and distinctive worlds of our solar system.
Let me give you a quick tour of our solar system. If you headed outwards and looked back from 10,000,000 miles away you’d see something like this.
After Earth you get to the red planet, Mars, which of course has been visited by many undermanned probes. Three years ago the Curiosity rover about the size of a small car landed on Mars and has been trundling around its surface ever since.
Going on out, Jupiter, the giant of our solar system, with its four moons first discovered by Galileo in 1610 and they are very different — Io is sulphurous and volcanic, Europa is covered in ice, and we’d would like to know what there is underneath that.
There is Saturn, which has been explored by the American spacecraft Cassini. Saturn has many moons too, one of them is Enceladus, and this has an icy surface, and we now know that under one half of this ice there is an ocean of liquid. The biggest moon of Saturn is Titan, and the Cassini probe carried in its cargo a European robotic craft called Huygens, which was supposed to land on Titan — which is known to have an atmosphere — and see what it was like. It did precisely that. It took pictures of little rivers and a lake, but the temperature is -160°C and the liquid in those rivers is liquid methane, not water.
“The space probe Huygens landed on Titan and took pictures of little rivers and a lake, but the temperature is -160°C and the liquid in those rivers is liquid methane, not water.”
In the last year there have been other two other rather spectacular feats of robotics — there has been the Rosetta probe which was launched and eventually went in a big elliptical orbit and caught up with a comet and sent back pictures and landed on the surface of the comet and continued to follow the comet which was closer to the sun in August, and is now moving away. People thought it might have broken up into two, but it didn’t do that.
The other exciting discovery last year was the New Horizons’s flyby of Pluto and its moon, Charon. These two probes, Rosetta and New Horizons, I think they are remarkable because this is sending back pictures from 10,000 times further away than our moon, and it’s using technology which is 15 years out of date.
Both of these probes were more than 10 years on their journey to their target and, of course, you freeze a design of the spacecraft several years before launch. So, think what they could’ve done with modern technology, think how your mobile phones change in 15 years, and think how frustrated they must be in order that they couldn’t do a better job.
Well, what’s going to happen in the next 50 years? I think robotic probes are going to go to all these bodies of our solar system, tiny ones rather like iPhones beaming back signals, and also I think that we can expect large robotic fabricators in space, away from the Earth, building huge structures, huge mirrors under zero gravity, solar energy-collectors and things like that.
The best arena for robots is obviously in space, and they’ll happen there [upon] maybe mining material from the moon or from asteroids. So I think in the next half a century we will have large construction projects in space of things like huge mirrors but there may be other possibilities.
But will other people go? This is Harrison Schmitt, the last person man on the moon, a geologist, in 1972. Of course, if he had been on Mars he might have found some things that the Curiosity probe didn’t notice, but it would be more expensive to send him and bring him back than to send the Curiosity probe. I personally think that the future of sending people into space is going to be different. Because as robots get better and better, the advantage of humans goes down. There is really no practical case in the future to send people. So if people go, it’ll only be as adventure and nothing else.
“As robots get better and better, the advantage of humans goes down. There is really no practical case in the future to send people. So if people go, it’ll only be as adventure and nothing else.”
I think therefore, unless the Chinese want to do a big spectacle — which they might want to do by sending someone to Mars — if they want to do something spectacular, they clearly can’t just send people back to the moon because it wouldn’t top what the Americans did 50 years earlier. They’ve got to send someone to Mars. They might do that.
But failing that, I think the future of man spaceflight lies in the private sector. The reason for that is that they can accept higher risk than NASA could impose on civilian astronauts. The Space Shuttle was launched 140 times, it failed twice, each of those failures was a big national trauma. Whereas test pilots are happy to except that sort of risk, so are many adventurers like Ranulph Fiennes and people like that — they are the kind of people who will go into space.
We know that Space X has already docked at the Space Station, it will be launching people within a few years into low-Earth orbit and there are plans to take people on a five-day trip round the back side of the moon and back, going further from Earth than any humans have ever been. I’m told they’ve sold a ticket for the second flight, but not the first, and that may tell you something [laughs].
There are even plans to go round to Mars and back — that’s a year and a half — and the ideal crew there is a very stable couple, happy to be cooped up for 500 days and old enough that the radiation damage doesn’t worry them. The alternative, of course, is the one-way trip to Mars and there would be plenty of volunteers for this — Elon Musk has said he hopes to die on Mars, but not on impact, and he is now 44 years old so he might make that in 40 years.
“By the end of the century there will be communities of people living, either freely floating in space, or perhaps on Mars. They’ll be intrepid, rather crazy libertarians, and they won’t be the typical people who are astronauts now. The post-human era will begin away from the Earth, maybe in one century or two.”
So I think by the end of the century there will be communities of people living, either freely floating in space, or perhaps on Mars. They’ll be intrepid, rather crazy libertarians, and they won’t be the typical people who are astronauts now. I think we would cheer them on and wish them good luck in using all the techniques of genetics and cyborg technology to adapt themselves to this alien environment.
They will adjust themselves, and within a century or two their progeny will be almost a different species — they would be evolving, not on the Darwinian timescale, but on a timescale of technology. So the post-human era will begin away from the Earth, maybe in one century or two.
The other question, then, is will they be cyborgs or will then the machines take over completely? I’ll come back to that in a moment.
So life will spread out to these remote parts of the solar system, but is there life out there already? As we know, there might be some freeze-dried bacteria or something on Mars, there might be something swimming under the oceans of Europa or Enceladus, but I don’t think that’s very likely. If we widen our horizons from our solar system to the realm of the stars, far beyond the range of any probe we can now conceive of making, then things are much more exciting.
We’ve learnt, in the last 20 years, mainly in the last five years, that most of the stars you see in the sky are orbited by retinues of planets, just as the sun is, and that there are many planets like the Earth.
There are two techniques, they are both very simple. One technique for inferring planets is if you have a planet orbiting a star, then what actually happens is both the star and the planet orbit their centre of mass called the barycentre. The star goes round in a little circle and the planet goes round in a big circle because it’s heavier.
But very precise Doppler measurements of the star — if you measure its spectrum — then you can detect this circular motion. This method has discovered many planets the size of Jupiter or Saturn — the giants of our solar system — but it can’t detect planets like the Earth because the Earth induces a motion of only about a centimetre per second in the sun’s motion and that is too small to be detected.
There is another method which has revealed planets like the Earth. This, again, is very simple in principle. If you observe a planet and we are in the plane of its orbit so it transits in front of the star, then when it moves in front of the star it blocks out a bit of the starlight. You see a click every time it comes round. If, for instance, are you are looking a long way away at the Earth and the sun, then every time the Earth went in front of the sun, the sun would get fainter by one part in 10,000 because the Earth is 1% the radius times minus four of the area of the sun.
This spacecraft called Kepler spent three and a half years looking at an area of sky about seven degrees across and measuring the brightness of 150,000 stars in that part of the sky — measuring the stars with the precision of one part in 100,000, and doing this over and over again every hour and looking for cases when you see regular dips, indicating planets passing/transiting in front of the stars. They have found many, many hundreds of planets, and remember they only see the ones where we’re in the plane of the orbit — so for every one they find you expect hundreds more.
There are many planets, and there are a huge variety — they’re not all like our solar system, there are Jupiter-like planets, so close to their star that the orbital period, the year, is only four days, and a lot of planets intermediate in size between Neptune and the Earth.
“There are many planets, and there are a huge variety — they’re not all like our solar system, there are Jupiter-like planets, so close to their star that the orbital period, the year, is only four days”
But the special interest attaches to planets that are like the Earth, like the Earth in two ways. One way is in having about the size of the Earth, and the other way is in being at the distance from their star such that water can exist — neither so close it boils away nor so far away that it stays frozen food, the so-called habitable zone. It’s very exciting that there are stars with planets like the sun orbiting them, and if you extrapolate to the galaxy, then it’s a fair bet that there will be about one billion stars with planets like the Earth orbiting them in our galaxy.
It’s frustrating in a way that all the evidence is indirect — you don’t see the planets; you infer them by the way they affect the motion of the star or the brightness of the star by moving in front of it. It’s hard because they are much fainter than the star by a factor of a billion or so and very close in the sky to the star.
Let’s imagine that an alien astronomer had a big telescope and was, say, 20 light years away from the Earth that’s orbiting a nearby star. And suppose the alien was looking at our solar system. The sun would look like an ordinary star and the Earth would look, in Carl Sagan’s phrase, like a pale blue dot very close in the sky to its star, our sun and a billion times fainter. The next generation of telescope will be able to have a go at this.
The alien astronomers looking at the earth would have found that the shade of blue in this pale blue dot was slightly different depending on whether the Pacific Ocean or the land mass of Asia was facing them.
So they could have inferred that the continents and oceans, they could have inferred the length of the day, something of the climate and seasons, and maybe something of the atmosphere. Those are the kind of observations which [the next generation of telescope] will be able to make of nearby planets around nearby stars.
There are two things you could do — one is if you could actually resolve the planets from the star, high-angular resolution, the other thing is if you can take a very precise spectrum. So by observing slight changes in the overall spectrum, when the planet is in transit in front, and disappears behind, you can separate out the planet spectrum from the star spectrum. So this is the kind of thing we’ll be doing in the next 10–20 years.
The question everyone asks is, ‘Is there any life out there?’, and the answer here is we just don’t know, we don’t know for a fundamental reason — we don’t know how life began on Earth.
“The question everyone asks is, ‘Is there any life out there?’, and the answer here is we just don’t know, we don’t know for a fundamental reason — we don’t know how life began on Earth.”
Darwin tells us how the simplest life formed nearly four billion years ago, and evolved into the wonderful biosphere of which we are a part. But the first life, what caused the transition from biochemistry to the first metabolising reproducing structures, is not yet understood. There are theories, but there is no consensus on how this happened. Therefore, we don’t know whether it was a rare fluke that we wouldn’t expect to happen anywhere else, or whether it was a kind of thing that would’ve happened anywhere in any of these Earth-like planets.
Even if that simple life existed, then we don’t know how many contingencies occurred which were crucial to the evolution of life from simple beginnings, to the present day. Therefore, even if simple life is common, we don’t know whether advanced life is common.
I would guess that in 10 or 20 years we’ll understand the origin of life, that’ll tell us whether it’s likely, it’ll tell us also probably whether the only chemical basis is the DNA/RNA that we know about, or whether there could be other chemical bases for life. But I don’t think we will know about intelligent life unless we’re very lucky.
There are projects being done to actually look for evidence of something artificial, some beeping that’s not from anything natural, that’s coming from space. In fact, there’s a new programme of this kind funded by a Russian investor called Yuri Milner — he’s putting $100m into this and I’ve agreed to chair his advisory group. This is going to involve radial and optical searches more sensitive than those done before. None of us holds out more than a few percent chance of any kind of success, but the stakes are so high that it’s worthwhile, and good for Yuri Milner for spending his money on this and not on a yacht or a football team. It’s a very exciting quest.
If we did detect anything, then I think it would not be civilisation, it wouldn’t be anything organic, it would be some machine. It could be that one or two centuries from now, machines, maybe away from Earth, will have taken over from us. Therefore, if you imagine a time chart of the Earth’s history, there’s been four and a half billion years before any civilisation emerged, then it’s existed for a few thousand years at most, but then there are billions of years ahead when the machines will dominate.
“If you imagine a time chart of the Earth’s history, there’s been four and a half billion years before any civilisation emerged, then it’s existed for a few thousand years at most, but then there are billions of years ahead when the machines will dominate.”
Therefore, it’s unlikely that we will catch another planet if it’s tracking out a similar evolution to the Earth, when it’s in this organic state. It’s far more likely that it’ll be way ahead of us and if we detect something it won’t be something sending off a message, it won’t be civilisation, it’ll be some possibly malfunctioning machine which is a descendant of some long-dead civilisation.
Incidentally, we are not surprised that planets are common around stars. A star forms by a dusty gas cloud starting to contract under gravity. Even if you’ve got only a very slow spin, as it contracts, the spin will increase, just like when the ballerina pulls in her arms. So around the protostar will be a dusty disc spun off. In that dusty disc, the dust will agglomerate into rocks, and then into planets, hydrogen will condense out, etc.
This is a generic process which leads people to expect the planetary system [to be] common, but of course we don’t know the details of the final planets. We already know from Kepler’s data that there’s a big variety in the configuration of planets. We see places where stars are forming — this is Eagle Nebula, 7,000 light years away — we see stars forming there.
Although we don’t understand the evolution of living things, we do understand the evolution of stars. Low-mass stars burn their nuclear fuel very slowly, high-mass stars burn their fuel much more quickly and are much brighter and bluer. Stars that are bigger and heavier than the sun, so 10 times heavier, die more explosively. The Crab Nebula is one of the most famous objects in the sky, which is the remnant of a supernova explosion witnessed by a Chinese counterpart of the Astronomer Royal, in the year 1054AD. At that place in the sky we now see this debris which is expanding and will eventually merge with the interstellar gas.
If it wasn’t for [supernovae], we wouldn’t exist. This is a great discovery that was first recognised by Fred Hoyle, a Cambridge astronomer and my predecessor. He realised that if it wasn’t for these supernovae, we wouldn’t be here.
“If it wasn’t for [supernovae], we wouldn’t exist. This is a great discovery that was first recognised by Fred Hoyle, a Cambridge astronomer and my predecessor. He realised that if it wasn’t for these supernovae, we wouldn’t be here.”
When a big star is towards the end of its life, it’s trying to get as much nuclear as it can — so it’s turned hydrogen to helium in the outer layers, then it turns helium into carbon, carbon into oxygen and so on. You can calculate that it will have a sort of onion-skin structure where the hotter inner layers are burnt further up the periodic table — the heavier elements.
Then, when everyone’s out of fuel completely, it faces a crisis, its core collapses, and it blows off its outer layers, making a supernova explosion like the Crab Nebula. Then that debris which consists of all these elements, merges with the interstellar gas, and then forms into new stars.
These calculations which they did show that you can understand why oxygen and carbon are common, why gold and uranium are rare. The work was done mainly by Hoyle and three of his colleagues — Margaret and Geoffrey Burbidge and William Fowler.
This is work done in the late ’50s, they showed that we are literally the ashes of long-dead stars, or the nuclear waste from the fuel that makes stars shine. They showed that our Milky Way Galaxy is really a sort of ecosystem where gas starting off as pristine gas in the Big Bang, grows into stars, and the low-mass stars are still around, but the high-mass stars burn out, fling the stuff back into interstellar space, and then condense it into new stars.
So each of us contains atoms from probably hundreds of different stars all over the Milky Way, which lived and died more than five billion years ago. Then our solar system condensed from gas contaminated by all of them.
Our galaxy, as I said, contains 100 billion stars. But it’s one of many. Our nearest big neighbour in space is the Andromeda Galaxy, two million light years away. Galaxies are the main large-scale features of the cosmic scene. There are about 100,000 galaxies in this volume of space, they’ve all been charted.
“The Andromeda Galaxy is going to crash into our Milky Way in four billion years, so don’t worry too much.”
You might think it’s pretty hopeless to understand anything about galaxies because they’re far away, we can’t do experiments on them, and they change very slowly — a star orbits around the hub of a galaxy once every 100,000,000 years. But of course we can do this in the virtual world of our computer. The Andromeda Galaxy is going to crash into our Milky Way in four billion years, so don’t worry too much.
Another thing we can learn from simulations is about what the galaxies are made of. We find by this, and other techniques, that galaxies contain not just the stars and gas you see, but they contain about five times as much stuff in what we call dark matter. This is a swarm of particles that don’t emit or absorb light, but they collectively produce more gravitational force than everything else — they hold galaxies together. So in the universe we know that dark matter is an important constituent. There is various evidence which tells us that there is about five times as much dark matter as ordinary atoms that make up gas and stars.
What about before the Big Bang? This year we celebrate the 50th anniversary of the discovery by Penzias and Wilson at the Bell Labs, that intergalactic space is not completely cold. It’s warmed to about three degrees above absolute zero by radiation, which we now know has a black body thermal spectrum and is the afterglow of radiation that was hot and dense in the beginning of the universe.
If you imagine the universe was originally hotter and denser than the centre of a star, it expands, the radiation cools and gets diluted, it’s still around, it’s got nowhere else to go, and it fills the universe. It’s an afterglow of the universe’s hot, dense beginning.
Evidence like that has led to our standard time chart of the evolution of our universe since the Big Bang. We have quite good evidence of what the universe was like when it was one second, or maybe even a nanosecond, old, because that’s when hydrogen and helium interacted and were in proportions that we can check. That’s a time when everything we now see in the observed universe would be condensed down to the size of our solar system.
People sometime wonder when they’re told that the universe started off as an amorphous Big Bang, ‘How did it end up so structured?’, because you know the second law of thermodynamics, which says that structures get washed out — why doesn’t that happen here? It’s the effect of gravity — if the universe is not completely smooth to start with, then slightly over dense regions lag behind and eventually condense out.
Now, in doing these calculations, you have to put in some initial fluctuations, and what is very gratifying is that we don’t put in the fluctuations ad hoc, they’re fluctuations which we can actually observe. They’re observed by the Planck spacecraft, which was launched by the European Space Agency, which produced a wonderful map. It shows the background of the early universe, it shows some regions are slightly hotter and some regions are slightly cooler, and you can study the spectrum of these fluctuations and feed those in. If you feed those into your calculations and run them forward, you get something which looks like our present universe.
This raises a new set of questions — what causes the fluctuations, why does the universe expand the way it does and why does it contain the observed mix of atoms, radiation and dark matter? The answer requires us to look back even further than the first nanosecond.
Most theorists that we’ve got to go back to when our observable universe was squeezed not merely to the size of a solar system, but down to the size of an apple. We had a process called inflation which took place in there.
This is a theory which is speculative because the physics is beyond what we can observe, but there are some ways in which we can combine different theories, and so I think it is gives us a possible idea of why the universe is expanding the way it is.
How large is physical reality, and is our universe which we observe [only] a tiny fraction of what exists? Part of the universe that we can see is limited by how far light’s been able to travel since the Big Bang. There’s no reason to think it stops there any more than there’s reason to think that the horizon, when you’re in the middle of the ocean, is where the ocean stops.
“Almost certainly, the universe goes on hundreds of times further than we can see and it may go on so much further that”
Almost certainly, the universe goes on hundreds of times further than we can see, and it may go on so much further that. But that’s not all, because this is the aftermath of our Big Bang, and there are ideas, including one called eternal inflation, whereby the aftermath of our Big Bang is just one bubble in a sort of infinite ensemble, and that there are many, many universes — it’s just one version.
There’s another idea that there are many universes which are three-dimensional spaces embedded in some fourth dimension. There may be other universes far away from ours, but if that distance is measured in fourth dimension, we wouldn’t know about it.
So this opens up a new set of topics — are all these universes the same in their geometry and the physical laws governing them? They may be. If not, there’s an exciting possibility — some of them may be like ours and allow complexity to evolve, whereas others may be kind of sterile in a sense that gravity may not exist; they may not have the right balance between microscopic forces to allow periodic tables and chemistry; they may not last long enough; galaxies may not form, etc.
So if that’s the case then we’d live only in a tiny subset, this is what’s called anthropic selection. How many Big Bangs are there? Maybe it’s just one, if there are many, we want to know if the physical laws vary in them. If they don’t, then we are faced with the laws of nature that we have and they’re fundamental, or if there’s a variety then we won’t be in a typical one, we’d be in one of a subset which allows complexity to evolve. Kepler thought that the orbits of the planets were governed by exact mathematics. We now know that was barking up the wrong tree — we now don’t think that the planets are on orbit at a fundamental — they’re accidental environmental features of our solar system.
It may turn out that what we think of as the fundamental laws of nature, the mass of a proton, the strength of gravity etc, are environmental accidents in our Big Bang and the fundamental laws are on a far deeper level. We don’t know.
Before leaving the multiverse, some people ask me, ‘Do [you] take it seriously?’. I would quote this anecdote that I was on a panel where we were asked how seriously we took the multiverse, and I said, ‘On a scale, would you bet your goldfish, your dog or yourself, I was nearly at the dog level’.
“When I was asked how seriously I took the multiverse, I said, ‘On a scale, would you bet your goldfish, your dog or yourself, I was nearly at the dog level’.”
Andrei Linde, who invented the eternal inflation model, he said, ‘Well, I’ve worked for 25 years in this theory, I bet my life on it’, later, Steven Weinberg — the great physicist — when he was asked this question he’d happily bet Martin Rees’s dog and Andrei Linde’s life [laughs].
If you want to understand the real beginning of the universe, when the entire universe was squeezed down to subatomic sizes, then clearly we need a theory which incorporates both the quantum principle and gravity. As you probably know, this is unfinished business for 21st Century science.
Only 1% of scientists are either particle physicists or cosmologists — 99% work on the third frontier, the frontier of complexity. The most complex things we know about are us, human beings, and we are incidentally halfway between cosmos and micro-world. The geometric mean of the mass of a proton and the mass of a star is 50kg — in the factor of two, I guess, of the mass of each person here.
So we are halfway between, and that’s why it’s not surprising that to understand ourselves, we need to understand atoms and molecules but also the stars that made those atoms. We are very complicated, and indeed even an insect is far more complicated than a star or a galaxy.
The biological world is the most complex, and that’s not surprisingly where lots and lots of scientists work, far more than work on particle physics or cosmology.
I’m often asked, ‘Does being a cosmologist, an astronomer, give [you] a different attitude to the everyday world?’, and I have to say it doesn’t really. Having spent a lot of my working life among astronomers, I can assure you they’re no more relaxed and serene than anyone else — they fret just as much about minor matters. But I think there is one respect in which they are different in their perspective from most educated people — in an awareness of a far future. I think most people, familiar with [evolution], nonetheless think that we humans are somehow the culmination of it all — it has led to us and we are the end of the evolutionary tree as it were. No astronomer could believe that — we can’t believe it because we know that our sun is less than halfway through its life.
The sun has been shining for four and a half billion years, it’ll be more than five billion years more before it flares up and engulfs the inner planets. The expanding universe has far more time ahead of it, maybe even an infinite amount. To quote Woody Allen, ‘Eternity is very long, especially towards the end’ [laughs].
So any creatures that witness the death of the sun, five or six billion years from now, and send us a postcard, they won’t be human. They’ll be as distant from us as we are from a bug. Darwin himself realised that no living species will transmit its unaltered likeness into the distant future.
“Any creatures that witness the death of the sun, five or six billion years from now won’t be human. They’ll be as distant from us as we are from a bug.”
But there are two changes since Darwin, first, our timespan for the future is far longer than his, but secondly and more importantly, it’s clear that future evolution will not be on the Darwinian timescale, it’ll be far faster, it’ll be on a technological timescale.
So therefore the number of things that can happen, the number of changes that could happen in the next five billion years, is far, far larger than even the complexities of biological evolution. So I think we should bear in mind that we may not even be at the halfway stage in the emergence of complexity.
Despite all that, even in this concertina timespan stretching billions of years into the past and into the future, this present century is a special one. It’s the first in the Earth’s 45 million centuries so far where one species, namely ours, can determine the planet’s future.
So an important and salutary thought for all of us, whether we’re astronomers or not, is that we are inhabiting a special place — this pale blue dot in the cosmos — and we’re also its custodian in a special time.”
This talk took place st Second Home, a creative workspace and cultural venue, bringing together diverse industries, disciplines and social businesses. Click here to find out who’s speaking next.
