Rise of the Discworld
You might wonder why, having talked about time-travel and gravitational waves, I'm dealing with something so basic and ancient as the shape of the Earth. Surely nobody believes the flat earth hypothesis in the 21st Century? Actually, quite the opposite. Flat-earthism is getting more popular every year, especially online.
As a few examples: the youtuber TigerDan925 (a flat-Earther) has over 26,000 loyal followers on his channel, the Flat Earth Society (along with many other organisations) has been rekindled under the leadership of Daniel Shenton and every day on Instagram I see hundreds of people passionately claiming that "globe-heads" are ignorant sheeple part of a global????? conspiracy. NASA photographs are all faked apparently, and the world's governments are prepetuating the round-Earth lie for all sorts of reasons, often to undermine the Christian Bible (which sometimes talks about the Earth being flat). How has this happened?
Woah, dude, they might be onto something!
If you've ever run across a flat-Earther you'll find they're not pitch-fork wielding yokels who cower at electricity. They're often well-spoken people who can defend their position with what sounds like good evidence. And that's part of the reason flat-eartherism appeals to many; their claims can be backed up with Scientific-sounding ideas.
A lot of the videos and articles by flat-Earthers contain nuggests of genuine Science. The FES (Flat Earth Society) website makes frequent reference to things like "Earth's axis symmetry" and "the Northern annulus" which sound like terms you'd hear in a legitemate astronomy class. Some of their arguments are so good in fact, you can't immediately spot why they're wrong.
Case in point: I'm a well-educated Scientist and I had a couple of moments researching this article where I went "hang on, how does a round Earth explain that?" Seriously, some of the flat-Earth arguments were so subtly wrong I didn't even notice where the mistake was at first!
I'm quite proud of that incidentally, not ashamed. I would be a bad Scientist if I decided "flat-Earthers are wrong" before hearing their evidence. As it turns out, their evidence is flawed in numerous ways, but the fact I had moments of "hmmm, that's interesting" is proof, I think, that I really was going in with an open-mind. So, to any flat-earthers reading this blog, I come in peace, waving a white flag.
But therein lurks the danger. I'm a well-trained Scientist and I couldn't immediately debunk some of their claims (not immediately anyway). Flat-Earth arguments are multiply confused it's true, but they do sound accurate so it's no surprise a lot of people can be seduced. To illustrate my point, here's a screenshot of some equations on the FES website:
When I first saw this I thought "hold on, that looks like Gauss' law and it proves that...ah, wait, no it doesn't." As it happens, those equations are being misused, but this doesn't look like the work of a lunatic, in fact the person who wrote this obviously has some mathematical training. Now, to be abundantly clear, every flat-Earth argument I've looked at crumbles under examination, but they often look fascinating, even to someone who knows what they're doing.
Most Flat-Earthers aren't Crazy or Stupid
One of the most interesting flat-Earth arguments I came across was actually on a German website and it said the following "das kabunkenfult ist der keine nicht; un spletze jarra die holten. Diese globe est eine kreiss mit der flatenzich." That's a very interesting sentence when you translate it into English.
Except it isn't, because it's not a real German sentence. That sentence is fake. Sure, there are a few genuine words which you probably recognised, but if you aren't fluent in German, you wouldn't know. It works the same with pseudoscience. It's so much like proper Science that if you're not an expert you can't distinguish what's real from what's not.
This is why a lot of sane, intellligent people end up believing things which are false. You hear technical words, see a few diagrams or equations, and if you're not careful, you can go along with it. Even the people perpetuating pseudoscience probably don't realise they're doing it.
If you're not confident on Science (actually even if you are) flat-Earth arguments can be persuasive because, and it shames me to admit this, they're taught better than real Science!
A Bad way to Learn
Most people are educated about the Earth being round by their parents before they even go to school. It's one of the first simple facts everybody learns: the Earth only looks flat because it's big and we're small. The problem is that most kids (myself included) are merely taught it and are never given evidence. Or, sometimes, the evidence given is wrong e.g. Columbus sailing around it, which can actually be explained on a flat-Earth.
We also don't spend much time proving the Earth is round in school. As a high school Science teacher I barely mention it. I just assume primary schools and parents have done the job, allowing me to move on to other stuff (although after researching this, I'm going to change that).
So, naturally, a lot of people grow up "knowing a fact" without the foundation for how we know it's true. When they come across clever-sounding flat-Earth arguments they find themselves questioning ther knowledge. Self-doubt is healthy and accepting facts dogmatically is not, so in a sense their decision is a sensible one.
Because many people aren't equipped to defend the round Earth, they reasonably abandon it when counter-arguments are suggested. Flat-Earth arguments look like they're based on reason (albeit sloppy) and the round-Earth is usually dictated as "thou shalt know this fact", making the flat-Earth seem more appealing. This is something we obviously need to fix.
Shut up, stupid!
I once overheard someone debating a flat-Earther and they said at one point, mostly out of frustration "Look, every Scientist believes the Earth is round, are you honestly going to disagree with millions of Scientists?" The flat-Earther responded, quite fairly, "yes".
I don't agree with the flat-Earther's cosmology but I do agree with their stance: you don't have to agree with something just because a clever person says it's true, that's NOT how Science does things.
Anyone can make mistakes and sometimes an entire Scientific community can get stuff wrong (look at phrenology). One of the reasons Science works is because we don't take somebody's word for it, we check it over and over. We're also open to new ideas and prepared to chuck out well-accepted theories because...
It's fine to disagree with someone in authority
It's fine to disagree with someone cleverer than you
It's fine to challenge the accepted view
It's fine to come up with your own hypothesis
Science isn't a democracy where we go with majority opinion. You're allowed to suggest any hypothesis provided you can a) test to see if it's right and b) are willing to back down if the evidence contradicts you.
Science is a dictatorship but the dictator isn't "the head of Science" (there is no such job, fortunately), the dictator is nature herself. If you want to know the truth you don't trust someone who makes the claim, you test it.
So, let's do that. How can we test that the Earth is round without relying on images from NASA, who would obviously be part of the conspiracy?
1. The Horizon Exists in the first place
If the Earth were flat you would be able to see across it, particularly at sea where there are no obstacles in the way. Yet we find our scope of vision comes to a limit after a few kilometers and using binoculars doesn't reveal more. Sitting in the Atlantic ocean of a flat Earth, you should be able to see America and Africa simultaneously, yet we cannot.
You'll find flat-Earthers claiming this is to do with objects being so far away that they appear small, but the distances across horizons are often shorter than the heights of clouds which you can still see comfortably from the ground, so no dice there.
Also, the higher up you go, the further you can see which wouldn't make sense if the Earth were flat. If Earth was a pancake, being higher up would give you no perspective advantage. Yet, we have a horizon - a limit to vision in all directions, which things appear over (rather than shrinking into) which we can see past only by raising altitude, as I've demonstrated in my beautifully drawn diagram below. Not to scale, obviously.
2. People in Australia can see stars Europeans can't
If the Earth truly was flat, the "northern hemisphere" would really mean the "inner circle" around the pole. Countries in the southern hemisphere like Australia are near the edge of the disc (as shown in the picture at the top of the blog). If the Earth is flat, people in these two circles will be looking at the same sky and while they might disagree on where the stars are, all the stars should be visible. But that's not what we observe at all.
In Sydney, for example, you can't see Ursa Major, which everyone in Europe is pretty familiar with. There are some parts of northern Australia where you can see it at certain times of year (again near the whole Horizon thing) but in the South, you just can't. Likewise, from northern Finland you can't see The Southern Cross (which Australians are so familiar with they have it on their flag).
Now to be fair, flat-Earthers point out that Australians and Europeans will see stars in different places because they're both looking "up" at different points of the Earth's surface, and I agree with them, but it doesn't explain why some stars are completely hidden.
If you and a friend stand on opposite sides of a room and look up, you will see a different part of the cieling above you, you'll disagree on where the light-fixture is but you both still see the light, it's not hidden from anyone.
But what we experience in reality is that some features of the sky cannot be seen in the North and vice versa. How can two people both look upwards, yet be looking in the opposite direction? Their "grounds" must be opposite to each other as well i.e. they are standing on opposing sides of the Earth.
As I've tried to show this on the diagram below. In a flat Earth, the UK and Australia should be looking up at similar skies as they're on the same side of the North pole. But in a round Earth, there are some stars the Australians and people in the UK simply can't see. Technically, I should point out that the opposite country of Australia is actually Spain, but you get the idea...
3. Day and Night happen at Different Times
OK, a similar idea to the previous one. When it's daylight in the UK, it's the middle of the night in Australia (I've skyped with Australians and this is definitely true). This poses no problem to a round-Earth model because as the Earth rotates, different parts of its surface point toward the Sun. Now, the flat-Earth counterargument does initially seem sensible. They argue that day and night work like this:
Here we get the timezones occuring in the right order and day/night cycling back and forth. The Sun hovers above the Earth and goes around in a constant circle, with the moon in opposition. This does solve the day/night problem, but it raises countless others (not to mention how the moon is sometimes visible during the day). I'm going to ignore the problem of having a Sun that size (short version: it's not possible) because I want to stick with simple proofs anyone can test. And there are plenty of ways in which the above can't be right.
Firstly: This isn't how light works. Get a torch and shine it down on a plate. You'll notice that one part of the plate is forming a little circle of "daytime" - fine. But lower your head to the plate and look up. You can still see the torch, even from the dark regions. On a flat Earth, the Sun should be visible, even during night-time.
There's also the problem with the shape of that light patch - it's an oval. It has to be in order for day/night times to occur at the right times, but why would a spherical Sun be creating an oval light patch? This isn't what light does. The only way to get an oval shap from a spherical light source is to have the ground curving...which defeats the whole point of the flat-Earth. Simply put, the flat Earth model means you also need to reject the theory of light as well.
Secondly: This wouldn't explain sunsets. If the Sun were moving around in a circle like that, we'd see it getting smaller and smaller as it got more distant, before gradually growing in size as it "rises" again. But that's not what happens, the Sun stays the same size - suggesting it's always the same distance from us. Sunsets just wouldn't happen in the above picture.
Thirdly: Circular motion doesn't work like that. For an object moving in a circle, some kind of influence must be pulling it toward the centre (what's called the centripetal influence). You can prove this by swinging a ball on a string and notice that the force pulling on the ball is your hand. If the Sun is looping around in circles, there must be some kind of force pulling it in toward the centre, and there isn't anything hovering over the North pole.
You might immediately say it's the gravitational pull of the moon, but there is a major problem with that, which I'll get to in point 10. And if the Sun really is moving in a circle as described, we'd have to abandon the first law of thermodynamics because something is pushing the Sun round constantly through the atmosphere, generating energy from nowhere. And even if we did accept gravity was holding the Sun and moon in place, their orbit would actually look like this:
4. Eclipses happen
Every so often (as perfectly predicted by the round-Earth model) the moon is shadowed by some object. This can't happen with the flat-Earth because there is nothing between the Sun and moon. In the flat-Earth view the moon always has direct line of sight to the Sun so nothing should ever get in its way.
Flat-Earthers do accept this criticism incidentally, and so have come up with a solution. There's another object floating above us: the shadow object. We've already seen there must be a third object in the sky holding the Sun in place (completely invisible), but now we need a fourth to explain lunar eclipses. This object interacts with sunlight (in order to cast a shadow) yet is somehow invisible from Earth - implying it doesn't interact with sunlight?
The same is true the other way round. Solar eclipses can happen in the middle of the day i.e. the Sun is directly overhead and some object drifts in front of it, obscuring it from Earth. There's no doubt the object causing Solar eclipses is the moon (we can watch it happening) so to create a solar eclipse in the above model, the moon would have to spontaneously duck out of it's orbit, drift across the planet and go UNDERNEATH the Sun. When solar eclipses happen, nobody reports seeing the moon shooting across the sky to get in position.
Interestingly, the FES does address the issue of the lunar eclipse by inventing the shadow object (and also making sure it breaks the known laws of optics), but they are strangely silent on the issue of a solar eclipse...apart from a few who pose the existence of yet another heavenly body "the anti-moon".
5. The Sun illuminates clouds from below
Take a look at the beautiful image above. You can see the sun setting (bottom half disappearing first, then top half) and interestingly, the light is hitting the undersides of clouds. You can watch this phenomenon during almost any sunset. Now here's the thing, according to the Flat-Earth model, the Sun is circling above the clouds.
Even if we somehow accept that the sunset is an illusion (I don't, but let's just say) how could we explain the Sun, above the clouds, illuminating them from below? It can't be reflection on the sea's surface because reflected light always bounces off at the same angle it hits (i.e. the sun's rays would be too low to hit the clouds), yet somehow we get illumination on the underside.
1 - 5 Refraction and Perspective saves all
If you've read any flat-Earth literature (and I've recently read a lot) they have clever-sounding answers to the above problems which, without fail, explain it as a side effect of "refraction" or "perspective". Refraction causes light to change direction when it goes from one substance to another and you've probably done experiments with prisms in school, or seen straws appearing in wierd places in glasses of water, or swimming pools seeming shallower than they really are. This is the kind of thing refraction can do. Perspective is what makes objects look smaller as they are farther away.
However, according to flat-earthism, refraction is some magical phenomenon which allows light to bend and twist in any way you can think of. Sunsets, sunrises, eclipses and the horizon are all explained in flat-earthism with a simple "because of refraction and perspective" defence.
But refraction and perspective can't make the Sun move down when it should get smaller, it can't make the top of an object appear before the bottom, it can't bend light upside down to illuminate clouds, it can't make stars invisible and it certainly can't bend shadows. But, let's just say, let's just say we accepted flat-Earthers claims that refraction and perspective explains away all my evidence above. The next five tests don't have anything to do with either of them.
6. Water boils at 100 degrees
This one's a really easy test. When you heat water it moves around more. It also expands and turns into vapour, leaving the pot and carrying away into the air. The more air above you, the harder it is to get the water to leave the pot. By contrast, the less air above you, the easier it is to force the water upwards (less air fighting it back down).
The idea that water boils at 100 degrees is only half the story because it actually boils at lower temperatures when you're on top of a hill (less air above you so less heat energy needed to overcome it), and if you put it under lots of pressure (like a pressure cooker) you can have water well over 100 degrees in liquid form.
Now, in the flat-Earth model, there are two ways of accounting for the shape of our atmosphere. Either the air goes on forever in all directions or it forms a dome. If air is infinite then going up a hill should make no difference to the boiling point of water - go up high and you've still got infinite air above you. Which is why most flat-Earthers argue the atmosphere must look like this:
Straight away you can see the problem. The atmosphere is very high near the north pole, but less high near the southern tip of Africa or Australia. In other words, water should boil at a higher temperature the further north you go (the higher the dome is above you).
People in Sweden should be able to boil water at 120 degrees for instance, and people in Australia perhaps closer to 115 degrees or something (probably a more dramatic difference). But that isn't what we observe.
Water's boiling temperature is constantly 100 degees at sea level wherever you are. The only way of changing it is to go higher. And, what's more, the change in height is the same everywhere you go. You can check it for yourself but it's every 290 meters climbed, shaves 1 degree off your boiling temperature. And that principle is also true everywhere - suggesting the height of the atmosphere is the same everywhere. This couldn't happen in a flat Earth.
7. There are two Tides
High-tides occur because the water is moving away from land and forming a sort of watery-hill in the middle of the ocean. Explaining this is impossible under a flat-Earth model (I'll get to why in point 10) but even more problematic for the flat-Earth is that high tides occur on opposite sides of the world simultaneously.
Explaining one tide on a flat-Earth is just about doable. You could talk about the Earth tilting, the moon somehow pulling on the water (not using gravity though), but to explain why there are always two tides at different "ends" of the flat-Earth is something I've never heard a flat-Earther give a satisfactory explanation for.
In a flat earth this amounts to two separate peaks of water spontaneously rising up and moving around the plane of the Earth with no mechanism. The round-earth theory explains both tides very well however. The moon's gravity pulls Earth's water toward itself, but as the Earth spins it throws water out and away in the other direction. The overall effect, predicted by round-Earth theory, is that it ends up creating a lozenge shape and therefore two tides...
8. The colour of the Sky
When you look through a large amount of air you see something different to what you get looking through a small amount. In an airplane, the sky often looks darker above you than it does near the horizon. At sunset, the sky near the horizon looks orange/red while the sky above looks a darker blue. During daylight, the horizon usually looks a bit paler than the sky overhead. There are all sorts of effects going on in these examples but the conclusion is the same every time: thin air is a different colour to thick air.
Now go back to our flat-earth dome. Someone in the north pole should see an even distribution of sky colour because they're right at the centre. But if you live in southern Australia, things are very different. Cast your eyes north and you're looking through ten-times the atmosphere you'd be looking through if you look to the south. The sky should look different colours in different directions. In fact, anywhere on Earth (except for at the pole) you should see this effect, one horizon should be a different colour to the other, because one involves looking through less air.
What we actually experience is a uniform sky colour everywhere. The horizons match during the day and only change during sunset/rise. What kind of shape could possible explain the fact that everybody seems to be looking up at the centre of a dome?
This one gets a bit complicated, but I'll cut out all the mumbo-jumbo and keep it simple. Magnets always have a North and a South pole. It's impossible to get a lone North-poled object for instance, because if one direction is North, the other must be South. By definition, magnetic fields always cancel each other out at both ends and you can't have what are called "magnetic monopoles" (Dirac if you're reading this, shut up).
The Earth has a huge magnetic field which we can test using compasses. The Flat-Earth has the idea of a North pole covered, that's the point where all the magnetic field lines connect. What it has difficulty with is the South pole.
In the flat Earth model, there is no such point as the South magnetic pole so the entire rim of the world has to act as the South pole in order to explain compasses; the field lines branch out from the centre and that's why our compasses point along these axes. There are a few problems with this straight away in terms of how magnetism works, but let's just be generous and say it could happen.
You could imagine a bunch of bar magnets all glued together in a wheel with their North poles pointing to the hub. This magnetic wheel now presents us with three major problems.
First problem: Field Lines Take two compasses and have them parallel to each other at the equator. Except, it turns out you can't do that. In a flat earth model, the magnetic field lines are all pointing away from each other at angles, so two compasses on the equator (which I've drawn below as the black rectangles) will point in different directions. Parallel compasses or magnets would be impossible on a flat Earth.
But let's just say we could do it somehow, let's ignore that problem and assume we somehow could put magnets parallel to each other at the equator, maybe they're really close to each other, too close to see the divergence. As we walked toward the South pole, the magnets are going to follow different field lines and will eventually turn out to be pointing toward two different parts of the South pole - they would spread out.
But that's not what happens. Firstly, the magnetic field lines are parallel at the equator and they end up pointing toward each other the further South you go. How can we have magnetic field lines being parallel at the equator, but converging on a point the further South you go? On a ball, as shown below.
Second problem: Aurora Australis You've heard of the Northern lights and the mechanism is pretty simple. When the Sun ejects clumps of high-energy particles they go flying into space and sometimes get caught in Earth's magnetic field. As they get funnelled in toward the North pole, they end up crashing into the atmosphere. The result is a beautiful light show. It happens at the North pole because that's where the magnetic field lines are pointing.
In a flat Earth, you'd expect these lights to happen at the North pole where the magnetic field is most concentrated, but not at the south pole where the magnetic field is weak. And yet, we do get a light display there, often at the same time as the Northern lights. Many explorers in the Southern region of the world have seen the Aurora Australis for themselves and you can too - it's a bit of a stretch of the term "testable" but you're already walking across the world holding two compasses, why not see the lights as well?
The problem is that the South pole in a flat-Earth is too weak to cause the lightshow. It's the same amount of magnetism, just stretched over a large diameter (the edge of the disc). The only way to make the South pole more magnetic, and permit the lights, would be to introduce lots of "south poles" on their own, but since magnetic monopoles aren't a thing, this is impossible. No way round it I'm afraid, Southern Lights shouldn't exist on a flat-Earth.
Third problem: a Flat Earth shouldn't be Magnetic anyway There's a good reason for the Earth to have a magnetic field. A large sphere of liquid iron is constantly rotating around an inner core of sollid Iron (and Nickel). This grinding of two large ferromagnetic bodies means a lot of electricity is being moved around, and when you have moving electricity you have a magnetic field. In other words, it's a byproduct of electricity moving in a sphere. There's no other way to generate a magnetic field that big.
A round earth comes with a satisfactory explanation for why it has a magnetic field - which matches everything we know about electricity and magnetism (and can test). A flat earth provides no explanation for why the Earth even should be magnetic in the first place. How would a magnetic field be generated on a disc?
Which brings me to the big one. The one I've mentioned a few times and held back. In flat-earthism, it's impossible to have the Sun going round in a circle because of a rather bizarre feature of Flat-Earth theory which all flat-Earthers have to accept. It's not usually the first thing they come out with but the day/night model they rely on so heavily cannot work because it relies on the existence of gravity, and guess what...
10. Flat-Earthers do not Believe in Gravity
I've included a screenshot here of me pointing to a statement on the FES website, just so you know I'm not making it up...
There are two reasons Flat-Earthers think gravity doesn't exist. The first is that any object has a centre of mass, a point which gravitationally pulls other objects toward it (I'm simplifying it a teensy bit there A-level physicists). The centre of Earth's mass is in the centre obviously, and gravity points toward it. In a round Earth this is no problem because anywhere you stand gravity pulls you inward toward the core. But on a flat Earth gravity would pull you sideways at the edges of the world. Australian gravity would happen at an angle and it clearly doesn't. Flat-earthism and gravity don't go together. So rather than abandon flat-earthism, they abandon gravity.
Secondly, gravity pulls things into a sphere. That's what it does. Every Sun in the sky, every planet, every moon, every pulsar, every quasar are all round. Gravity pulls in all directions and so, like a piece of paper crumpled from all sides, everything gets rolled into a ball. A big flat object (like a flat Earth) couldn't exist for long. It would buckle under its own size and gravity would crush it together to form a spheroid. In other words, gravity is the ultimate flat-Earth killer. So, naturally, flat-Earthers reject it. As it says on their website "objects simply fall".
Except they don't.
In 1774 a group of Scientists carried out an experiment (repeated countless times by enthusiastic physicists and one you can do it yourself) where you hang a pendulum next to Schiehallion mountain in Scotland and the pendulum doesn't hang straight down, it tilts toward the mountain. Of course it does, the mountain has mass, so it has a gravitational pull and causes things to tilt as they fall, rather than in a straight line toward the earth. Objects do not simply fall.
You can watch the moons of Jupiter through a telescope orbiting their planet in a circle. Gravity is the only way to explain this circular motion. Objects do not simply fall. The tides show the entire ocean gradually lifting up and pointing toward the moon wherever it moves. Objects do not simply fall. The infamous Cavendish experiment (which you could also replicate) shows two large spheres being attracted to each other, not toward the ground, because of their gravitational attraction. Objects do not simply fall. We can watch, through our telescopes, clouds of dust being pulled together to form Suns, woven by some invisible all-pervading force. Objects do not simply fall.
And even if they did, even if they did, why isn't the Sun falling toward the Earth in the flat-Earth model?? If objects simply fall, then there is nothing holding the Sun up and it should just crash into us, along with the moon, the shadow object, the anti-moon and so on.
As we showed earlier, a Sun moving in a circle needs to be held in place by something. It can't be gravitationally attracted to the moon because gravity doesn't exist in flat-Earth world. The tides can't be explained by the moon's influence either. Ultimately, the flat-Earth theory has to reject gravity, but in doing so, you also abandon the concept of day and night as well. No matter how you look at it, gravity is the nail in the flat Earth coffin.
What you have to believe
Believing in the flat-Earth isn't simple. In order to match what you see to the flat-Earth, you have to also give up on light and optics. You have to reject the first law of thermodynamics. You have to reject the existence of tides. You have to reject electromagnetism. You have to reject gravity. And all these ideas are testable and endlessly verified.
Yes, some of the things flat-Earthers point out are puzzling at first, and some of them don't have immediately obvious explanations. But I'm afraid that's all they are - quirks of perception which can be explained with a better Scientific understanding. Round earth theory has survived not because Scientists said it was true, but because it accounts for every bit of evidence, making countless testable predictions.
The Earth is round and anyone saying otherwise is not crazy, or stupid, they just don't understand the gravity of their claim. Pun intended. James out.
Flat Earth map: Wikipedia
Flat Earth equations: The Flat Earth Society Website
Matilda: Miriam Ruiz
Horizon: Mariza Knezevic
Day and Night: The Flat Earth Wiki
Saucepan: Shauna Xani
Northern Lights: NorthernLightsTours
I remember standing in the ICT office at school once, discussing the new Star Wars movie, when someone walked in and said "you guys are such geeks". I looked at her and said "you realise that's not an insult to us? I teach Science for a living and these guys are ICT wizards; geek is absolutely the correct word!" Zing! But it's defintely interesting that Sci-fi fans are often STEM-minded people too. Why is that?
First, we have to accept that fiction itself (let alone Science fiction) is a very weird thing. I mean, why do we like hearing stories which are fake? It would make sense for humans to be invested in hearing true stories, but why do we get so excited by events we know never took place?
Every evening before bed, I sit down and read. I read plenty of non-fiction, but I also read novels and short stories. I spend hours doing it and have so many fiction books I overspilled my shelves years ago. I'm also a movie nut. Every weekend I go to the cinema and see whatever the new release happens to be.
But what a strange thing to be interested in. I spend large amounts of time and money reading/watching stories which are - no other way of putting it - lies. Rather than being angry at a storyteller for trying to decieve me, I welcome the experience of made-up tales. I'll even criticise a film if the actors aren't convincing...if they've failed to lie to me. If I see through their performance and remember they're not really their character, I'm annoyed because it reminds me it's just Nicholas Cage I'm watching, rather than his character.
Sometimes we even prefer fictional stories to reality. The highest grossing films are never documentaries and the bestselling books are always novels rather than non-fiction. We talk about what happened on Doctor Who more than we talk about what's happening in the UN, we cry at movies when something emotional happens to a character who never existed, and we write blogs listing our favourite fictional Scientists.
There are scads of essays by literary theorists on why humans enjoy fiction and how good stories are told. There's also a bunch of nonsense about how the mind works and how all stories follow the same structure (looking in your direction Joseph Campbell). I'm not going to argue my own views on why storytelling matters, or why I think these literary theorists are wrong. Instead, I'm going to focus on my all-time favourite genre: Science fiction.
But isn't that even crazier?! I'm a man who's dedicated his life to promoting real Science, and I absolutely love movies which lie about it. Why do I love movies in which the main characters can shoot lasers from their hands, travel in teleporting police-boxes and go to war with alien races? After all, my ultimate passion is getting people Scientifically educated...
What exactly is Sci-fi?
There's a word for all of those geeky genres they stack next to each other in Waterstones: speculative fiction. This encompasses things like horror, fantasy, sci-fi, alternate realities, steampunk etc. etc. All fiction is made-up, but speculative fiction refers to stories which are so far away from reality, you'd immediately know it wasn't true if you heard it.
If I told you the story of Girl on the Train for example, I could easily convince you it was true. It has murder, adultery, depression and alcoholism in it - they're things which are known to happen in the real world. But if I told you the story of Conan the Barbarian, you'd immediately recognise it wasn't true. Magic doesn't exist...as far as you muggles know.
I've met people who consider Sci-fi to mean "things which take place in the future". But that immediately removes something like Back to the Future, which takes place in the past. Or what about something like Independence Day which is about alien invasion in the present day? Or even Independence Day Two which is about what happens to a franchise if it's been left for decades and the director returns and fails utterly, utterly, to capture the fun of the original.
I want to avoid giving the horrendous answer of "I know it when I see it" so here's my approximate definition of Sci-fi which I think covers 95% of cases: Sci-fi is a genre in which Scientific laws match those of the real world, but Scientific knowledge does not.
What I mean is that Sci-fi takes place in a reality where there are unbreakable Scientific principles which the story must obey, and they are the same as our Universe's - but there are also fictional Scientific ideas as well e.g. discoveries which haven't been made, technologies which aren't invented etc. etc.
Terry Pratchett, author of the Discworld novels, once said he preferred writing fantasy to Sci-fi because in fantasy there are no rules; you can bend the world to fit your story. In Sci-fi you have to follow Scientific law.
For Harry Potter, magic is a real thing and it can be used to achieve anything JK Rowling wants it to. Need your characters to fly? Magic. Need your characters to turn into other people? Magic. Invisibility cloaks? Magic. This isn't a criticism by the way, I've got nothing against the fantasy genre, but in fantasy you can have anything happen and justify it by saying "magic did it". In Science-fiction, if you want anything to happen, you have to give a plausible justification.
Optimus Prime is a sentient robot (not yet known with current knowledge) but his evolution is explained in terms of cybernetic advancement (permitted by the laws of Science). He can travel from one planet to another via a spaceship, but he couldn't just wave a wand and delete Megan Fox from existence (as much as we might want him to). For him to cast a spell would break the rules of the Transformers Universe, because they're the same rules as our universe.
Sci-fi isn't set in the real world but it's set in a real world that could be ours. Laser guns and light-speed ships aren't things which exist, but they might one day. Fantasy tells stories of the non-real and impossible. Sci-fi tells stories of the non-real but possible.
What about Batman?
There are some grey areas to my classification system because genres of fiction, like species of living creature, don't always fit neat categories. The obvious example is good ol' Batman. Batman is set, more or less, in the real world. He has no superpowers and doesn't use magic, he's just an ordinary guy who has a lot of tech and time on his hands.
Occasionally, Batman stories veer into Sci-fi territory (or even fantasy) but the majority of Batman's adventures could, theoretically, happen in today's world. It would be possible for someone to dress up as a bat and go round fighting crime. In fact someone already has. Look up "The Bromley Batman" - I promise that news story will brighten your day.
There are other franchises which blur the boundaries. In Warcraft for example, there is magic, but the magic is given a set of rules and structures which mimic Science. It's a parallel Universe that has underlying laws, they're just different to the laws of our world. Or take The X-Files which sometimes covered stories of aliens (plausible), but sometimes stories of ghosts (debateable) or werewolves (nonsense).
Even our beloved Star Wars is set in a mostly Sci-fi world, but includes The Force, which is basically magic...
There was a time (and by that I mean, all of history up until the late 1980s) when speculative fiction, and Sci-fi in particular, was sneered at by those in proper literary circles. Science fiction was often associated with cheapness and popular writing - because heaven forbid anything popular be considered worthwhile. I've read plenty of essays from the early 20th Century, most of them hitting peak venom in the 1960s and 1970s, condemming Sci-fi as a childish genre, even accusing it of making people stupid (Quite the opposite is true incidentally, as many Scientists originally got interested in the subject from childhood Sci-fi).
In an attempt to quel this snobbishness, Isaac Asimov suggested we divide the genre into two categories. Sci-fi was the cheap thrills stuff - quickly written, predictable, sensational stories with 2D characters and terrible Science, and then there was "Science fiction" - carefully written, literary works with carefully drawn characters and well-researched ideas. For a time, this disctintion was necessary but nowadays people are less uptight about it.
Today Sci-fi and Science Fiction are synonymous, we just recognise that some Sci-fi is good quality and some is not, the same with any genre of fiction. Thanks to novelists like H.G. Wells, Isaac Asimov, Robert Heinlein, Richard Matheson, Arthur C. Clarke, Neal Stephenson, Eric Brown, Richard Paul Russo, Kevin J. Anderson, Aldous Huxley, C.S. Lewis, Dan Simmons, Alan Moore and Phillip K. Dick, literary circles are finally starting to recognise that some Science fiction is the work of truly talented writers creating masterful works of fiction...it just happens to feature laser-swords.
Besides, the very first work of Science fiction (Frankenstein as far as I'm concerned) is a masterpiece and a deserved classic. Yes, Sci-fi has its cheap rubbish, but so does the well-respected genre of emotional human drama...I mean have you ever tried to read anything by Nicholas Sparks?
So what's the big deal?
I can't speak for every Scientist but I can definitely explain why Sci-fi is important to me. It's because Sci-fi, more than any other genre, asks the question "what if?" Sci-fi imagines worlds different to our own, but not so different as to be out of reach. Sci-fi is about possibilities and it's this optimism I'm enamoured with. Sci-fi offers us something more tantalising than fantasy fiction...something which might just be possible one day.
As a Scientist I'm always interested in finding out how the Universe works but that's not all there is to it. Scientists also want to know what is possible. If you put our knowledge of nuclear physics to good use, for example, we get power stations, use it for aggression and we get the cold war. Science is a powerful instrument in our species' evolution and I think it's healthy for us to speculate about the possibilities - good and evil.
I don't know why fiction as a whole is important to us, but I doubt anybody does. Perhaps it's because we like to connect with people so much that even fictional people will do. Perhaps it's because we want to invest in people's lives without the stress and worry of "real-life drama" - you can put a book down when you're not in the mood. Or maybe it's just that we all want to go on adventures and experience the world, so we allow ourselves to do so through imaginary stories.
Whatever it is about fiction that appeals to us, Sci-fi plays on another important human desire: the desire to ask questions. We want to find out about the strange edges of human knowledge, to find out what the world is like and how we could make it different. We like to imagine different worlds because it helps us put our own world in perspective. And that's why I love Sci-fi. Not because it allows me to escape reality, but because it puts me fully in touch with it.
Also, spaceships and robots.
Lightsaber geeks: Wired
Voldemort and doctor: Gawker
Jetpack: Tom Gauld
If you ask a Physicist whether time travel is possible, they'll usually respond by saying "Well...erm...it depends...sort of...uh...look a DeLorean!" You might wonder why they don't just come out and say nobody knows. The reason is that this answer, while technically true, misses the point. We don't know if people can time-travel but we aren't shrugging our shoulders either.
If you'd asked the Wright brothers if airplanes were possible on December 6th 1903 (the day before their landmark flight) they wouldn't have said "we don't know". They'd dedicated years to studying aerodynamics and while they didn't know for sure, saying they had no idea would have sold it short.
Time travel might be the same. We've not achieved it yet but some Physicists take the question seriously. They might be lunatics, they might be onto something. So the best answer to the question of time travel is probably to say "maybe."
What is Time?
When I was about sixteen I used to do this thing whenever anybody asked me what the time was. I'd reply by saying "it's the thing we use to measure the passing of the day". I recieved many beatings.
But when you get right down to it, what exactly is time? Is it a human invention to keep track of stuff or is it a feature of the Universe with properties? This used to be a question for philosophers, but since Einstein published his theory of General Relativity, Physics has been able to provide an actual answer. Time is a real thing. Sort of.
Imagine a fish swimming through water. The fish can’t see the surrounding liquid but it can still detect its presence. As the water ripples and flows, the fish is aware of being pulled, but it never detects the invisible substance itself. The water is an unseeable background to the fish's universe.
We, like the fish, are currently sitting inside giant invisible everywhere-substances which stretch in all directions. They're like invisible fluids which permeate the Universe and although we can never see them, we can detect their presence. Physicists have a word for these invisible materials which contain reality: fields.
The field most people have heard of is the magnetic field. This field allows two objects to communicate with each other, repelling or attracting, and although we cannot see the field in its "naked form" we can see its influence on magnets and compasses.
And the magnetic field is just one of several. There are fields everywhere which are responsible for pretty much all of the Physics we observe. And time, according to General Relativity, is part of one of these fields.
Einstein's Purple Universe
Consider a piece of paper. You can describe it as having two sides: front and back. The two sides are distinct but they move as one. You couldn't fold just the front-side, for instance. By bending the front over you're also pulling the back with it. By being a piece of paper, it always has two components: front and a back. Well, it turns out some of the fields in our Universe are the same. They have two different surfaces which are linked together. How does that work?
Imagine there was a field everywhere which was purple. As it waved and whirled, we would detect the purple-ness being darker in some places and lighter in others. We could even develop complex equations to describe the movements of the purple field.
But here's the thing: we could, if we wanted, describe it as a red field and a blue field mixed together and overlapping. The purple field could be described and explained as a combination of two intertwinning fields which combine to make purple. You can’t affect the blue field without also affecting the red and vice versa.
The red and blue aspects of the purple field aren’t identical of course (blue and red are obviously not the same). But they are locked together, operating as one substance. You can't sensibly talk about the blue field and the red field separately, you can only talk about their combined influence. You may know that the electromagnetic field is like this, a composite field made from magnetic and electric components.
And, according to General Relativity, time can be thought of as being akin to the blue field - it is an aspect of a larger field made up of space and time linked together. This gets a bit weird but it's a blog on time travel, what do you expect?
It's hard to visualise but the three space-dimensions are fused with a fourth time dimension. Time is a quarter of the spacetime field. Although we think of time and space as separate things they are really mashed together into one purpley spacetime mixture. Which means whatever we do to one part of the field, we automatically do to the other parts.
Einstein wasn’t the first person to play around with this idea of time being a fourth dimension. Hermann Minkowski, another great Physicist, also conceived of time as being a dimension inseparable from the others. It was impossible, he argued, to define an object in the Universe without including a time dimension because time was always present.
Imagine an object that has all three spatial dimensions, but doesn't exist in the time dimension. An object which exists for zero seconds is an object which doesn’t exist for any amount of time. In other words: an object which doesn't exist. Time has to be considered a dimension like the other three, completely inseparable from the spacetime field. But this obviously presents us with a problem…
Time seems different
Time doesn’t act like the other three dimensions. For one thing, we can’t immediately see how much time an object takes up. If you see an orange you can immediately know its size (spatial dimensions) but you don’t know how long the orange has been around for, and how long it will last. You can’t immediately see whether the orange will be plucked from the tree tomorrow or in a week’s time. The time dimension is partly hidden from us.
Time also seems to be a one-way dimension. I can easily take a step left and then right. Or jump up and then down. Or forward and then backward. The three spatial dimensions are completely reversible. But time isn't. I can only move through time forwards.
Time is also different in that we only see along it backward to the direction we're travelling. Although I'm moving along the time axis in a forward direction I can't see where I'm going, only where I've been. What I mean is that I know what happened five seconds ago, but I don’t know what will happen five seconds from now. Why is time so different?
In all honesty, this is the heart of the time-travel problem. Either time truly is a different type of field-aspect or time secretly is like the spatial dimensions at a deep-level, there are just other factors which get in the way and give it the illusion of distinctiveness. What's referred to in Physics as a "broken symmetry". So, what do we know about time so far?
Forward to the future
Time travel to the future is not only possible, it has been achieved numerous times thanks to our knowledge of Relativity. One of the strange side-effects of the spacetime field is that it can be bent and squashed depending on how you’re moving.
It sounds bonkers but Relativity tells us the faster you move, the slower time passes for you. As you travel faster time slows down.
Imagine you were holding a stopwatch and your friend held an identical one. If you started them simultaneously they would tick in perfect unison. If you then got in a rocket ship and moved extremely fast, you might decide 5 minutes had passed. But when you got back to Earth, your friend’s clock says that a whole week has elapsed. You were only travelling for 5 minutes, but time was going faster for everyone else so you are now one week into the future.
This isn’t just speculation. This experiment has really been done. In 1971 Joseph Hafele and Richard Keating (above) decided to put this bizarre claim of Einstein’s to the test by synching up atomic clocks and moving around the world in a jet plane. Sure enough, when the plane landed it had a different time-reading to the one on the ground, by several minutes.
Astronauts experience the same thing. If you spend several months in the ISS, travelling at 27,000 km/hour you’ll find when you come back, everyone else has aged more than you have. Astronauts really do accelerate forward in time.
Technically so do you! Every time you get in an airplane, a car or even run, you are slowing time down compared to everyone else. You are genuinely moving into their future. Usually this effect is very small, only a few microseconds, but travel to the future is completely accessible to us, you just have to move fast. So future travel is 100% possible. What about backwards? Again, the question is about whether is symmetric to the other dimensions or somehow unique.
One of the classic problems with backwards time travel is that you could, in theory, go back in time and change the order of events, violating cause and effect (one of the most important laws in Physics). The most famous example is the grandfather paradox.
Supposing I went back in time and met one of my grandfathers as a young man. And then I shot him. This prevents him from growing up and having children. My father is never born and neither am I. But if I have stopped myself from being born, that means I have never existed…so how did I go back in time and shoot my grandfather if I don’t exist?
This paradox is often touted as one of the reasons backwards time travel wouldn’t be possible. But that’s not actually true. The grandfather paradox can be solved quite simply. Hollywood has already given us several ways of answering the problem. I’m going to name each one after the most famous movie to depict it (Spoilers ahead).
Back to the Future 2 – Parallel worlds
In BTTF2, Marty McFly accidentally causes a paradox by sending some information back through time which changes the course of history - giving his arch nemesis control over his home town. But hope isn't lost because the original "good" timeline still exists and he can restore it. In this approach, when you travel back in time you create a parallel Universe.
If I go backwards in time and shoot my grandfather, I’m creating two alternate realities. One in which my grandfather survived (the reality I come from) and a new Universe where my grandfather is dead. Both Universe’s now continue forwards, oblivious to each other.
Terminator – Destroy your own Universe
In the Terminator movies, there’s a similar idea: going back in time creates a new Universe, but the difference is that the original Universe gets deleted in the process. This is how the robots try to win their war on humanity, by going back in time and killing the leader of the human resistence. This creates a new reality in which the humans have no leader, and the robots win.
If I go back in time using this reality, I backspace-delete the world as I go. I wind up back in the 40s, shoot my grandfather and create a new Universe, but the original one is gone. I’ve committed the ultimate mass genocide by wiping out the next 80 years.
Frequency – Universe overlap
The movie Frequency isn’t very well known but it’s one of the few movies to depict this third version of time travel. In this approach, you go back and make a change, which then overlaps with the real version. I make a change in the timeline and people in the future immediately detect the change I made.
Technically, Frequency and a few other films which have played with this interpretation (Bill & Ted, BTTF) cheat a little, but the idea is that my grandfather is simultaneously shot and not shot at the same time. People in the future remember him dying, but also remember him not dying. The two time-streams are invisible to anyone not affected, but for me, my grandfather and everyone we know, we end up with two sets of realities in our heads. Weird.
Twelve Monkeys – You Can’t Change the Past
In Twelve Monkeys, the main character goes back in time to try and change the world, but his very act of going back in time ends up fulfilling the bad thing he was trying to avoid. According to this interpretation, time is set in stone. So if I went back in time and tried to kill my grandfather, I would find it impossible. My gun wouldn’t work, the bullets wouldn’t hit him etc. etc. Since time is rock-solid and we already know my grandfather lived, travelling back in time changes nothing.
Doctor Who – Wibbly Wobbly Timey Wimey
Doctor Who has a very clever way of dealing with time travel – the rules are different in different situations. The same way gravity is different in different places, time’s behaviour varies from point to point. There are some events which can’t be altered and some which can. Some changed events create alternate Universes, some create overlaps. Having this loose set of time-travel rules is obviously useful for the writers because they can tell any story they want. So perhaps time, like many other substances, is just messy. Sometimes rigid, sometimes bendable.
Faster than light?
In the Star Trek episode The Naked Time the crew of the enterprise take Einstein’s time bending concept to the limit. If time slows down the faster you go, could you go so fast that eventually time would stop…and then go faster so time would reverse? The crew of the Enterprise discover that by travelling at an insane warp-factor they are able to travel backwards through time by going faster than light-speed (the Universal speed limit).
While going faster than light would cause time to reverse, there is a catch. Relativity says that travelling at light speed = time stopping, but it also says reaching light speed is impossible for objects with mass.
When you reach light speed your mass ends up becoming the square root of negative one – which is nonsensical. In other words, a massive object can’t do it. It would be like saying that drawing a four-sided triangle lets you travel through time. Maybe it does, but a four-sided triangle is an impossible thing. Likewise a massive-light-speed object is impossible, so it might work, but there's no way to pull it off. So does that mean time travel into the past is a no go? Not necessarily.
Most of modern Physics rests on two great theory-pillars. General Relativity and Quantum Mechanics (Quantum field theory to be precise). And both of these great theories suggest possible loopholes in the laws of Physics which would allow time travel to occur...
General Relativity's answer: Wormholes
If spacetime is a fabric which can be bent and twisted, could it be bent back on itself? As far as we know, the answer is yes. In what’s called an Einstein-Rosen bridge effect, it is possible to take spacetime, loop it and point it back at itself like a hosepipe. Travelling into one of these tunnels would spit you out somewhere else in space and somewhen else in time.
Normally the shortest distance between two points is a straight line. But if we're allowed to bend spacetime however we want, we could grab two bits of the Universe and bend them so that they're touching. To a creature inside the Universe, they would measure the distance between two points in spacetime as being far apart (like the glowing loop on the left side of the diagram). But to the wormhole traveller, you can shortcut from one part of space to the other (as shown by the tunnel in the centre of the diagram).
The only catch with a man-made wormhole is that we couldn’t travel any farther back than the earliest one we’d built. Suppose we built one mouth of a wormhole in 2017 and the other end in 2019. That would mean we could only ever go back to 2017. So I’m afraid nobody can go back and kill Hitler because nobody built a wormhole-mouth in 1939. The past has been made inaccessible to us, but if we somehow crack wormhole technology, it might not always be so.
Quantum Mechanics' answer: Richard Feynman
Quantum mechanics describes the basic laws which our Universe runs on. It's the fuel which makes Physics go. It's also remarkably weird because the laws of quantum mechanics are very different to the laws of the common sense world. Quantum mechanics is used to describe the fundamental particles of reality and it turns out they do some very strange things. Of particular interest is Feynman's work on something called Charge-Parity-Time (CPT) conservation.
Charge describes whether two particles will attract or repel. Parity refers to their directionality; whether they move left or right. Time refers to which direction they're moving through the spacetime fabric. Feynman was able to show, with unambiguous clarity and powerful experimental evidence, that all three of these properties can be reversed in unison.
Feynman discovered that if you reverse time, the laws of Physics look identical. There is nothing preventing particles from moving backwards. While time looks unsymmetrical from our perspective, to a particle it is completely symmetrical. The same way playing a video in reverse causes everything to move in the wrong direction, reversing the time-flow of a particle will also flip its parity and charge.
Particles travelling backward in time should appear to us as some kind of reversed-matter or “antimatter” which has been discovered. We can even make it. So is it possible that every time we make antimatter, we're also successfully creating backward-time-travelling particles? Yes.
To be absolutely clear, we can't prove absolutely that antimatter is regular matter moving backward through time. But it’s interesting that we've discovered something which looks exactly how backward-time matter is predicted to look. (For more on antimatter, check out the video below from one of my students)
Obviously, everyday objects aren't moving backward through time however. So why do tiny particles see time as symmetric, but this symmetry gets broken by the time we scale it up to the everyday world? There are lots of possible answers and none are completely satisfactory. This is what the time-travel question is about.
So, is time travel possible? Well...erm...kind of...depends on...sort of...uhh...look there's a Delorean!
I love science, let me tell you why.