No need to feel down
It’s been an interesting year hasn't it? England chose to sever its ties with the European Union and America decided to elect a former celebrity-businessman as the new president. Many famous and talented people died including Vera Rubin (discoverer of dark matter), Walter Kohn (inventor of density functional theory) and of course, Lemmy (inventor of Motorhead). OK, technically Lemmy died in 2015 but the pain's still real for me.
And, as if all this death wasn’t enough, we had the killer-clowns, the Dakota access pipeline fiasco, exploding phones, and I had to organise a school trip to London.
But while the news has been dismal and grim and miserable and doom-spreading (as it usually is) Science has made some awesome, uplifting, optimistic and life-changing discoveries (as it usually does).
There may be tough times ahead for Scientific literacy (link here) but we can never lose hope in the ingenuity and brilliance of our species. So, for the sake of everybody’s sanity, let’s take a moment to acknowledge the inspiring, mind-bending or just plain fascinating stuff Science and Technology achieved in 2016. In approximately chronological order.
Planet 9 (January 20th)
Michael Brown is the man responsible for demoting Pluto to dwarf-planet status (rightly so). But for those who objected, don’t hate the man too much - he's just brought the concept of a 9th planet back, only this time it's a lot bigger. Brown published data this year showing how some of the asteroids in the Kuiper belt are being pulled at a strange angle by some enormous mass floating in the darkness. We don't know what it is, but there's a very good chance we could be on the brink of discovering a whole new planet...ten times the size of the Earth. None of your wussy Pluto nonsense. #planetFeynman #planetSagan #planetAsimov
First Human Thought Transplant (February 10th)
This story was overshadowed by gravitational waves the following day, but I considered it one of the most remarkable discoveries of the year. Thought transplants had been achieved with mice in 2013 by Susumu Tonegawa at RIKEN-MIT, and in 2016 Matthew Philips of HRL laboratories reported the first rudimentary human version. By recording the electrical activity of a pilot’s brain, Philips was able to effectively ‘beam’ the thought-patterns into the brains of people learning to fly. The research showed that students receiving these ‘thought-beams’ picked up the skills much faster than the control group. It’s hardly The Matrix but it’s an exciting step.
Gravitational Waves Discovered (February 11th)
Physicists at the LIGO observatory announced the long-anticipated discovery of gravitational waves. I’ve done a video explaining it here, but the short and tall is that not only do gravitational waves confirm a century-old theory, they open up a new era of cosmological exploration. Probably the "biggest" story of the year - certainly one that future history books will record.
Humans and Neanderthals Interbred (February)
In mid-February (appropriately around Valentine’s day) we discovered, thanks to Sergi Castellano of the Max Planck Institute, that early humans were having sex with Neanderthals about 100,000 years ago. This is interesting because Neanderthals mainly occupied Europe and humans, it was thought, were still hanging around in Africa. To find human DNA in the Neanderthal genome suggests we may have left Africa a lot earlier than people thought, changing what we knew about human evolution.
Stem Cells for Stroke Patients (Early June)
Gary Steinberg of Stanford University published preliminary findings on the use of stem cells in stroke-victim therapy. Although the results are moderate and involve only a dozen patients, the use of stem-cells seems to have led to record-breaking recovery times for stroke victims, particularly in helping them regain mobility. Also, I have a confession to make regarding the picture above: the caption isn't true. Nobody enjoys the novels of Nicholas Sparks.
Biological Life After Death (June 11th)
This was another criminally under-reported study led by Alexander Pozhitkov at the University of Washington. While studying the death of mice and zebrafish, Pozhtikov discovered that death is not necessarily the end, in fact, for some parts of the body it is the beginning. Certain genes, associated with birth, cell-growth and cancer, are actually switched on 24 hours after the host organism dies. We have no idea why.
Juno Enters Orbit (July 5th)
After a five-year journey, the Juno probe successfully entered a stable orbit around Jupiter. Over a period of 37 rotations, the probe will gather data on the gas giant before its descent into Jupiter’s atmosphere (February 2018). This will give the human race our first glimpse inside a gas-giant planet. Hooray for Juno (the probe, not the Ellen Page movie).
Proxima b (August 24th)
In January, the European Southern Observatory launched the Pale Red Dot program to investigate the possibility of a planet orbiting our Sun’s nearest neighbour. On August 24th, they confirmed that not only does Proxima Centauri have a planet going around it, Proxima b, but it sits smack-bang in the goldilocks zone (more explanation here). In other words, rather than having to scour the Universe, it turns out there is a potentially habitable world in the next star-system! If only we had the means of getting there…
Breakthrough Starshot (April 12th)
I know this one should go earlier in the timeline, but it seemed like a nice way of linking the two stories. Mark Zuckerberg and Stephen Hawking announced the beginning of project Breakthrough Starshot, a new type of spacecraft based on solar-sail technology which, when built, will be able to reach Proxima b in 30 years, rather than the proposed hundreds of years it would take using conventional fuel-rockets.
Three-Parent Baby (September 27th)
Researchers led by John Zhang of New York helped deliver a baby boy containing genetic material from three adult humans. The couple who underwent the procedure suffered from a rare genetic disease which they would have passed to their son. By carefully altering the child’s DNA, Zhang was able to introduce DNA from a third parent and create a perfectly healthy baby, opening up a new realm of possibilities for parents who would otherwise be unable to have healthy children.
Robot Arm which can Feel Touch (October)
Nathan Copeland, who was paralysed after a road accident, volunteered for a revolutionary new technique in which a robot arm was wired directly into his brain. Not only does this arm respond to his thoughts and move as if it were his own, it feeds back sensory information, giving him back the sense of touch. I wanted to make some reference to the Transformers movie here about "you got the touch" but I realised there was a more obvious comment to make. We have just given a human being a fully-working, fully-sensing cybernetic limb.
First Successful Paralysis Cure (November 9th)
As if giving a paralysed man his sense of touch back wasn't enough, we've also made our first breakthrough in curing paralysis altogether. I'm not joking. Gregoire Courtine was able to successfully restore movement to previously paralysed monkeys by implanting wireless devices into their central nervous systems. One implant sits inside the brain of the monkey and wirelessly transmits a signal to the other implant in their legs, allowing the signal to bypass the damaged spinal column entirely, creating a newly reanimated cyborg-monkey! Human trials are a long ways off, but Courtine’s team has begun preparation at the CHUV University Hospital of Lausanne.
The EM-Drive Might Work (November 17th)
By far the most controversial discovery of the year, I’ve written about the EMDrive in detail here so I won’t go on. But there’s a possibility Harold White of the Eagleworks lab may have uncovered a new form of locomotion for spacecraft, as well as maybe settling the longest-standing debate in quantum mechanics. That’s if his research holds up to scrutiny of course.
Evolutionary Speciation Observed (November 28th)
One of the cornerstones of Darwin’s evolutionary theory is that a species can, over a long period of time, split into two forms of creature - a process called ‘speciation’. Unfortunately it usually takes such a long time that it’s not something we can observe (giving anti-evolutionists a pretty reasonable objection). However, thanks to Justin Meyer’s team at San Diego University, the process of speciation was finally observed for the first time in an extremely fast-breeding species of virus. It’s as if Darwin was onto something.
Psilocybin may help Cancer Depression (Early December)
Stephen Ross and his team at New York University announced the remarkable finding that administering psilocybin (the active ingredient in ‘magic’ mushrooms) to patients with cancer may significantly improve their depression. To be clear, this doesn’t mean magic mushrooms cure depression, but it’s certainly an avenue for investigation.
Preserved Dinosaur Feathers (December 19th)
Lida Xing from the China University of GeoSciences announced the discovery of a perfectly preserved dino-feather. Just like in Jurassic Park, a bit of fossilised tree-sap from 99-million years ago was unearthed containing a fully preserved feather. And now, I highly recommend you listen to the epic Jurassic Park theme by John Williams. In fact, as you listen, go back through my list and remember how wonderful we truly are.
In 2016 we carried out thought transplants, created cyborgs, discovered life after death, cured paralysis and invented new ways of improving people’s lives and helping people bring healthy babies into the world. Don’t feel down-hearted when you look around, my fellow humans. We’ve done a lot of great things, and we will continue to do great things because we are the human race and we invented Science. Take it away John...
We are not alone
In my last blog I calculated that the chance of life on other planets is very promising. But is that really something to get excited about? I mean, has anyone seen Independence Day? In that movie an advanced race called "the harvesters" (there's your first clue) discover our planet and attack. Their technology is so sophisticated that the entire human race is almost wiped out in 24 hours. We're only able to defeat them because we have Jeff Goldblum, American Flags and Apple product placement. God bless Hollywood.
It's a valid point though. Let's say there are thousands of civilizations out there. It's unlikely we'd be the most advanced one. There's a chance of course, someone has to be, but it's more probable other races would be ahead of us. And this could be a problem.
Imagine if the 21st century decided to declare war on the early 20th. That would be us with nuclear weapons, airplanes, radar, submarines, drones, chemical warfare, guided missiles and satellites against the bayonets and horses of the first world war. It would be a massacre (just like the real first world war).
The technology at our fingertips is unprecedented. Even within my lifetime I've found it hard to believe how quickly things have developed. 20 years ago the concept of video-calls, ipads and mobile phones was the realm of sci-fi. I still find chess-playing computers a bit spooky, let alone thumb-print recognition on Samsungs and a freaking space station orbiting the planet!
An alien race, even a few decades ahead of us, would appear like Gods. If they decided to attack us, have no illusions; we wouldn't save the day thanks to plucky human determination. We'd be trampled.
Many have even suggested that this is the most likely scenario. Look at how the conquistadors treated the native Americans or how the British treated the aboriginal peoples of Australia. The British "Empire" has a long history of landing in a place, enslaving/exterminating the locals and claiming the land simply because they could. Wouldn't there be a risk of aliens doing that to us?
As it happens, I don't think we have anything to fear. The idea of aliens declaring war on us is a bit far-fetched. Any species arising on another planet will face the same trials and challenges we do on Earth, which means we can look at how life evolves here to get an idea of how it would evolve there. And there are four basic truths which suggest we don't need to be afraid.
Reason 1: An advanced species won't be evil
People are fond of bleating on about how awful humanity is. We're the only species to invent war, the only species to invent racial genocide, the only species to knowingly pollute the environment etc. Give me a break. The tune is getting cliched and the lyrics are fundamentally wrong. Humans aren't the most evil species. We're just the most powerful.
Chimpanzees are known to form raiding parties and launch attacks on the next tribe over, killing the young and claiming the females for breeding. That's war, genocide and slavery right there. Orca whales have been observed catching sea-lions and, rather than eating them, tossing them back to freedom for a few seconds before capturing and repeating the process. That's torture for no reason other than sadism.
Point is, other species show exactly the same streaks of cruelty, greed, pre-meditated aggression and selfishness we do. Humans have not invented the concept of violence, we just use better tech. But I'll tell you something which does set us apart. We're the species who donates aid to countries hit by natural disasters. We're the species who volunteers to build schools in disadvantaged communities. We're the species who invented the concept of "peace-talks". Think about that. We're the species that goes out of its way to avoid conflict.
The vast majority of people, when they learn about slavery, the inquisition, the holocaust, the crusades, respond in the same way: horror. We're capable of awful acts but we're also capable of feeling shame. We are becoming self-aware because we can look back at dreadful things we've done and recognise them as such.
Thanks to the internet, today's youth are so much more savvy than I ever was. They've got friends all over the world, followers in different cultural pockets and they read blogs with views different to their own. Today's generation are more globally aware and more atuned to the big issues than any in history. And this is important. As a species advances technologically so does its quality of education and so, therefore, does its culture.
Yes, there are still yobbos who spew conspiracy claptrap on twitter and yes, there are still people who work in advertising. I'm not saying we're a perfect species, but I am saying "look how far we've come!"
I can't pretend we're living in a utopia of course. I know there's fighting going on. You can probably name several countries without even trying. But do you know why your brain can do that? Because the countries at war stand out...they're rare!
The human brain is very good at noticing things which stand out but we're not so good at putting that information in context. For example, there are currently around 16 countries locked in major wars. There are 196 countries in the world. Do the math. That's 92% of countries in the world currently NOT at war.
Don't get me wrong, I'm not trying to downplay the fighting currently taking place. But remember the job of the news is to focus on stories which stand out. News coverage highlights the extremes - and rightly so. We should all be aware of wars taking place. But the flip-side is that watching the news can give us a warped picture of what the world is actually like. Because you never hear about the peaceful countries your brain fuzzes them out. And so you start thinking of the world as a war-torn place. It's not. It's pretty peaceful.
When two countries disagree, the most you usually get is "tensions rise" or "heated political crisis". All-out war is something we usually try to avoid because we've been there and it's not nice. We're so lucky to live in these times and we ought to remember that more often.
And the further you wind back, the more sophisticated you realise we've become. Today we have institutions like Guantanamo bay and they get media attention because of how medieval they are. When we look at prisoners being tortured and brutalised, we are shocked that it's happening "in this day and age" because we know, deep down, that things are better today than they have ever been. We have an unspoken understanding that these violent acts are wrong because, as time passes, the human race is slowly getting over its desperate need to kill.
Slavery has been abolished in the Western world. Women have the right to vote and get educated. We look after the elderly rather than leaving them to die in workhouses. There are child labour laws. The Court of Human Rights exists, as does the Geneva Convention. We have healthcare, affordable electricity, heating and clean water for many. Point is: the more advanced a civilization, the more civilized its members.
An alien species may have a similar violent past to us but they will also have developed education, technology and Scientific understanding. Aliens might be cautious of humans, but I don't think they would attack and brutalise us...because we wouldn't do that to them.
If you've seen Avatar you'll remember the film has lots of gung-ho maniacs hell-bent on forcing the aliens out of their territory and I accept this may happen (I don't know which side of the film's analogy represents us) but there would also be people like Sigourney Weaver's character - people who want to learn and build bridges. There would be people like Jake Sully (the protagonist) who go in with a militant attitude, but who are willing to learn and change. An advanced race is an educated one and an educated race is, by its nature, peaceful.
Reason 2: An aggressive species doesn't last
You hear people talk about nature being red in tooth and claw and sometimes you hear them talk about how animals and plants live in harmony with nature. You want to grab them by the scruff and shout "make your mind up!" The reason people have a confused picture of nature is because nature isn't simple. There is no such thing as an aggressive or peaceful species, the reality is that every species has the capacity for both.
A crocodile who attacks a gazelle is rewarded - it gets a meal. But a crocodile who doesn't chomp down on a plover bird is also rewarded - it gets it teeth cleaned. Thing is, a planet has limited resources so every species has to learn coping strategies. And being constantly aggressive isn't a good one.
Take the Xenethsis immanis tarantula. It has learned to keep tree-frogs as pets - the frogs then consume insects who attack the spider's eggs. As a result the frogs get a meal and the spiders don't lose any young. If the spider had been more aggressive it would have eaten the frog and lost out.
Being aggressive also makes you more vulnerable to retaliation. If you fight everyone, you get attacked all the time and eventually you'll meet someone who can break you. Take the footage of the lion attacking a giraffe we all saw on Planet Earth 2...the lion got battered. The "peaceful" creature actually did more damage to the "violent" one. Because the truth is that giraffes aren't peaceful and lions aren't violent. They are both a mixture.
Any species learns this lesson by accident/instinct/inheritance etc. but a self-aware species like humanity has learned this lesson as an actual fact: don't go around attacking everything, you miss out on stuff. An alien race will have discovered the same optimal strategy. They will know that attacking a less-developed species might not be a sensible default position. Again, they might be ready to blast us out of the sky if we pose a threat but an alien species is (like us) going to have the capacity for cooperation as well as for aggression.
By contrast, a species who attacks everything will ultimately become extinguished. Either due to in-fighting or picking a fight with an equally capable enemy. Only a species capable of taking a step back and not pushing the button is going to survive. Alien races stumbling across Earth will have faced their own Cuban-Missile-Crisis, their own World War and they will have survived just as we have. Only a species capable of holding back on aggression will be around long enough to make contact with others.
Reason 3: Empathy
This is a small point, but a crucial one. A species that has the ability to learn is a species who can emulate creatures around them. This ability to "put yourself in another's shoes" gives rise to the most wonderful quirk of mental evolution: empathy.
Take the recent public outcry regarding the turtles on Planet Earth 2 (seriously, if you haven't watched that show, I'm ordering you to, it will make you a better person). We have no reason to feel empathy for turtles and yet we do. Because we're an intellilgent species we're capable of mentally synching with other creatures. We can recognise a common "desire to live" and we can respect it.
Some people are psychopaths, missing the capacity for empathy - these people often do will in business or marketing (for obvious reasons) - but most of us, when we see someone suffering, feel bad. Most of us, if handed a gun and told to shoot a puppy in the face, couldn't. I'm not even a dog person and I wouldn't pull the trigger. If the dog were attacking someone I cared about that might be a different story, but shooting a weaker creature for no reason just isn't something I feel any reason to do.
An advanced species is likely to be the same. They wouldn't attack us because they would empathise, even a little. They would recognise us as fellow travellers in this vast Universe, flawed just like everyone else. They would remember a time when they too were lonely, confined to their own world and they would take pity. They would see a commonality and would hesitate about pressing "fire" on the plasma cannon. Same way we would refuse to shoot a defenceless puppy.
Reason 4: There is no need to attack Earth
The first place a fledgling species is going to get its energy from will be the planet itself. Humans do this by extracting old bits of plant and fish from the ground, but it's no secret we can't keep doing it forever. The reason is simple: the population is increasing and the fuel is decreasing. Sooner or later we'll run out and we'll have to look elsewhere for our demands to be met. And any advanced species will face the same puzzle: adapt or die.
Fortunately, the Universe provides every planet with a quick-fix. We all come fully equipped with a burning Sun right on our doorstep. The Sun is a nuclear reactor and its output is enough to power thousands of Earths for billions of years...for free. All we have to do is use it. We wouldn't even have to go to war with anyone. Nobody gets exploited, we just switch on our solar panels and capture the light! Arguing over fossil-fuels while the Sun floats nearby is like sitting beside a bonfire and arguing over who owns the biggest mathstick. It's illogical.
Thing is, we have the technology and know-how to power the Earth from the Sun right now, we're just dragging our feet because it involves change. One thing which is definitely true of humans is that we don't like to change unless we're forced. We don't adapt until the very last minute and technically, right now, there isn't a pressing need to switch to a solar economy. There will be soon, and I'm hoping we've got the sense to actually do so, but right now we're getting away with being sluggish.
Every other species will face the same problems of course: switch to a renewable energy source or become extinct. So, it stands to reason that an advanced alien species will be a sustainable one. The only way to become a space-faring species in the first place is to switch to harvesting solar energy. A species which can't be bothered to make this change won't last.
And this is the ultimate reason we'd be safe...if an alien species is technologically advanced enough to provide for itself and go on adventures around the Universe, why would they possibly want to attack the Earth? We don't have anything an alien species would want! We've got water, various minerals, a molten core and a few other sundries, but (as I explained in the earlier blog) those things are found everywhere. The Earth is not even remotely unique or special.
Flying across a galaxy takes considerable effort. There is no reason to do that unless you're going to get something valuable. An alien race declaring war on us would be like us declaring war on penguins. They live far away, in a place we're not interested in, which takes effort to get to, and they don't have anything we need. They've got ice, water, rocks and a bit of algae but we can get those things at home with minimal effort. Why go to all that trouble?
Imagine if Trump decided to gather the united forces of the U.S. military to march on Antarctica and declare war on penguins. People would just laugh...I hope. Aliens would feel much the same about Earth. Interested maybe, but certainly not envious or threatened. So that's us - the Universe's penguins. And penguins are never dangerous.
The Earth from above
Once again, I think the Sc-fi franchise which best captured the future of alien contact was Star Trek. In that show we go touring the galaxy "to seek out new life and new civilizations". Our whole reason for exploring isn't for warfare or profit, it's to learn. Sometimes there are conflicts, even battles. But Star Trek depicts a galaxy full of races at different stages, trying to make their way in the Universe. Ultimately the goal of every living thing is just to get by. We will learn to cooperate. We will live long and prosper.
Dalek: Forbidden planet
Independence Day: srcdn
Scrappy: See earlier blog
The last few weeks I haven’t had a chance to write anything on the website, answer any of the questions or make a youtube video. The reason is because every year the Institute of Physics gets me to do a Christmas lecture on “big” Science topics (action shot from this year's event pictured above). It’s great fun, but most of my recent spare time has been spent researching, planning and organising that. But now I’m done for another year I can continue writing, so I thought I’d do a couple of pieces summarising the talk for those who weren’t there. Enjoy…
The man who invented Star Wars
The first person to suggest the idea of alien life (and therefore a huge amount of Science fiction) was Giordarno Bruno in the 16th Century. He reasoning was that the Universe is so vast, it's ridiculous to suggest our planet is the only one with life. Unfortunately, this didn’t go over too well with the Roman Catholic church because it presents a few sticky issues for crucifixion theology.
For example, in Romans 6:10 and Hebrews 7:27 we are told Jesus’ death happened once and “for all”. If there are aliens on other worlds we have to wonder: are they included in the “all”? If not, God doesn’t value and forgive every conscious being, if they are included, then how do they learn the Christian message? Jesus only dies once, so he can’t visit lots of alien worlds and preach to every being out there. These are fascinating questions, but they were uncomfortable in the 1590s.
So, naturally, the church had strong words with Bruno. Those words were: we’re going to burn you alive. Giordarno Bruno was, in a sense, the first martyr for Science because he was put to death for his commitment to astronomy. Today it’s perfectly legal to talk about the possibility of aliens however, so let’s do just that.
What is life?
Defining life is tricky. In the Star Trek episode The Tholian Web, the enterprise crew meet beings made entirely of crystal. In the episode Charlie X, they meet creatures who exist as disembodied faces. They meet sentient clouds of light in Metamorphosis and so on. Life is such a varied thing on Earth, how can we possibly define it for the rest of the Universe?
Perhaps there could be creatures made of plasma living in the hearts of stars. Perhaps there are beings living in extra dimensions of spacetime who inhabit the cores of black holes. Perhaps we’re being visited by alien life all the time but it’s so different to what we expect we don’t even recognise it.
If we say “life comes in an infinite variety of forms” then by definition, the Universe is full of creatures. We could argue that stars are living, as are nebulae and pulsars. Indeed, they might be, but that answer isn’t useful. If we want to discuss the question practically then we need to limit our scope.
For my money, NASA has come up with the best definition of life so far: “a self-sustaining chemical system capable of Darwinian evolution”. That’s a mouthful but it simplifies to: “very, very complicated chemistry.”
On Earth and other planets, we notice there are lots of simple chemical substances lying around. Crystals, rocks, gases, liquids etc. In fact, there’s more of these simple chemicals to be found than complex ones. Most of planet Earth is made up of things like molten iron, nickel, rocks and discarded Coldplay albums. Interesting chemically, but too structured to be considered "living".
Thing is, simple chemical substances are very regular. Rows and columns of atoms stack up to form crystals, metals and rocks, or they float about freely to make liquids and gases. Simple structures aren’t capable of doing anything interesting because they’re so organised. Chaotic structures like gases have the opposite problem – things float around so easily it becomes a chemical free-for all, nothing is stable enough to interact and evolve. So we have to rule out simple Chemistry and simple chemical reactions…they aren’t living in a meaningful sense.
All life on Earth (over 1.7 million different species discovered so far) is complicated. Atoms arrange in chains, spirals, sheets, clumps and clouds. Molecules are specifically shaped to fit through certain gaps and not others. Particles carry each other from place to place like nanoscopic machines, structures are pulled apart, rearranged and even self-constructed. The Chemistry of life is like an insane factory, and this is what we need…intricate, complicated and varied chemical reactions.
Chemistry is a bit like Lego. Atoms and molecules come in lots of different shapes and sizes, some more complex than others. Suppose you had one of those simple pieces which was just a single bump and hole. If your planet is supplied with these pieces only, all we get are chains varying in length. There is nothing more complicated or interesting possible. They either stack together in short chains or in long ones.
Well, most atoms are like that. The majority are shaped to accommodate one or two bonds and that’s it. If all your planet has to play with are simple atoms, life isn’t going to arrange itself into existence. All you can hope for are crystals, rocks, gases and liquids.
Some atoms, on the other hand, are capable of forming several bonds. Carbon and Silicon can form four, Phosphorus can form five and some of the metals go even higher under the right conditions. Out of all these multiple-bond atoms, Carbon is the smallest, making its bonds the tightest and strongest. This means Carbon atoms are really the most versatile out there. Although it has been suggested that life could arise from Silicon.
You do need lots of other elements besides carbon of course; Carbon atoms on their own tend to form simple crystal structures, but if you start throwing in other elements, you start creating complicated structures. There’s all sorts of analogies for this, here are two I’ve thought up.
When you’re making a soup, Carbon is like the water. On its own, pretty boring, but if you chuck in bits of vegetable, spices, stock etc. (other elements) you get something much more interesting. Or, if you prefer a more Christmassy analogy, Carbon atoms are like the branches of a Christmas tree and the other elements are the decorations. On their own, nothing happens, but put them together and pow!
One of the really exciting things we’ve discovered in recent years is that the chemicals found on Earth are not unique. In fact, the elements needed to form complex structures are found throughout the galaxy. The reason we know this is that different elements give off specific frequencies of light. If you look with the right kind of telescope you can analyse the light signatures of different parts of space and find out what chemicals they’ve got. And it turns out that the Earth is not rare at all.
Actually, the chemical building blocks used for Earth life are absolutely abundant wherever we look. Not only that, but the more advanced chemical structures (things like amino acids, which the elements combine to form) are also found elsewhere. The whole galaxy has the ingredients for life readily available.
If your complex chemical building blocks are all packed together in solid form, life doesn’t arise because they can’t move around and exchange information. Likewise, if your building blocks are floating freely and not coming into contact for any length of time, reactions are rare. Chemical processes, particularly complicated ones, really need to be sitting in a liquid.
Ideally this liquid should be unreactive so it doesn’t interfere with the chemicals floating in it, but it should be good at dissolving the ingredients. There are only a handful of such liquids known, the most common being water. We don’t know for definite that life needs liquid water but it’s a good candidate. Every time we find water on Earth, we find life, so it’s definitely favourable. Life might be able to form in other liquids like ammonia or hydrogen sulphide, but seeing as all those chemicals pretty common to the Universe it’s largely immaterial which one we pick.
Most planets probably have the right starting point for life but we need to address the other crucial factor: temperature. If your planet is too close to the sun it orbits, the liquids boil away and all those complicated chemicals burn up. If your planet is too far in the other direction things get cold. The liquids freeze solid and chemicals don’t have enough energy to react successfully.
In order for a planet to have liquids on its surface and keep the chemical ingredients from breaking apart, it has to be just the right distance from its star, orbiting in what’s called the Circumstellar Habitable Zone or…Goldilocks zone. Not too hot, not too cold. In our solar system, Earth is the only planet in the Goldilocks zone for definite (Mars might be, there’s a debate over how wide a goldilocks zone should be). And lo and behold, life has arisen.
To be clear, we don’t know how life actually got started and what else might be necessary (although the field of abiogenesis is yielding some intriguing clues). Perhaps you need a planet with a moon to set up stable tides for rock-pool formation, perhaps you need a magnetic field to protect you from cosmic rays, perhaps you don’t need either and life just “finds a way”. What we know with confidence is that life needs the right ingredients…which are found everywhere…and the right temperature to put them together.
Crunching the Numbers
Now we’re finally at the stage where we can do a back-of-the-envelope calculation on how likely life might be in our galaxy. First, take the number of Suns. It’s estimated to be between 200 and 400 billion. Let’s take the lower number to please the cynics. How many of those 200 billion Suns are like ours?
This is importanht because some Suns are less genteel than ours (particularly those near the core of the galaxy) and they’re so “bright” they destroy complex chemicals. But, fortunately, those evil Suns make up about a quarter of the galactic composition. Three quarters of the Suns in our galaxy are exactly like ours. So that’s 150 billion Suns. Right, how many Suns have planets going round them?
Well, the answer seems to be all of them. Planets always tend to form as a byproduct of star-formation (the dust which doesn’t get pulled into the Sun ends up orbiting in a disk until it starts clumping together to form planets). In fact, we’ve discovered over 3544 planets orbiting other suns – what are called exoplanets. So if we want to be realistic, we’re probably talking about 150 billion planets as well. Let’s be pessimistic though and assume only 90% of all suns have planets. Let’s also assume only one planet per Sun. That gives us 135 billion planets in our galaxy…minimum.
And how many of them are in Goldilocks zones? Well, of the 3544 we’ve discovered, about 7 of them are clearly in Goldilocks zones (that’s being really stingy with how narrow we make our goldilocks zone though). So that gives us 0.3% of planets forming inside Goldilocks zones. And what is 0.3% of 135 billion? 405 million.
There you have it. By limiting ourselves to carbon-chemical-based lifeforms only, the minimum amount of Suns, planets etc. we end up estimating that our galaxy should contain around 405 million possible worlds. Even if life is a tricky process to get going, those numbers are good. Life could be a 1 in a million shot and we’d still get 405 civilizations arising. And that’s just in our galaxy – which is but one of millions of billions.
Giordarno Bruno was right. It is statistically bizarre to suggest the Earth is the only planet with life. There's a possibility it might be the only planet of course, we don't know for definite yet, but the odds are very much in our favour. So, is there anybody out there? According to Science the answer is...probably!
George Lucas: amazon
Ian Malcolm: carboncostume
I love science, let me tell you why.