How Quantum Physics Explains Action Films

One of the key ideas used by cosmologists (yes, physics again, sorry) to explain away questions asked by annoying philosophical types is known as the anthropic principle. This has two forms (strong and weak) but the idea remains the same for both; that the reason for a situation being as it is is because, if it wasn’t, we wouldn’t be around to ask that question. For example, one might ask (as Stephen Hawking did in ‘A Brief History of Time’) why the universe is around 10 billion years old, a decidedly awkward question if ever there was one. The anthropic principle provides the simplest answer, stating that since organic life is such a complicated business and that the early universe was such a chaotic, unfriendly place, it is only after this vast amount of time that life forms capable of asking this question have been able to develop.

This answer of ‘because we’re here’ is a wonderfully useful one, albeit one that should be used with caution to avoid not answering valid question, and can be applied to problems that do not concern themselves directly with physics. One example concerns the origin of the human race, as we are all thought to stem from just a few hundred individuals who lived in East Africa’s Rift valley several million years ago. At that time our knowledge of weapons, fighting and general survival was relatively scant, and coming face to face with any large predator would have been a fairly assured death sentence; the prehistoric equivalent of a smart pride of lions, or even some particularly adverse weather one year, could have wiped out a significant proportion of the human race as it stood at that time in just a few months. Despite the advantages of adaptability and brainpower that we have shown since, the odds of natural selection were still stacked against us; why did we arise to become the dominant multicellular life form on this planet?

This question can be answered by listing all the natural advantages we possess as a species and how they enabled us to continue ‘evolving’ far beyond the mere natural order of things; but such an answer still can’t quite account for the large dose of luck that comes into the bargain. The anthropic principle can, however, account for this; the human race was able to overcome the odds because if we hadn’t, then we wouldn’t be around to ask the question. Isn’t logic wonderful?

In fact, one we start to think about our lives and questions of our existence in terms of the anthropic principle, we realise that our existence as individuals is dependent on an awful lot of historical events having happened the way they did. For example, if the Nazis had triumphed during WWII, then perhaps one or more of my grandparents could have been killed, separated from their spouse, or in some way prevented from raising the family that would include my parents. Even tinier events could have impacted the chance of me turning out as me; perhaps a stray photon bouncing off an atom in the atmosphere in a slightly different way could have struck a DNA molecule, causing it to deform the sperm that would otherwise have given me half my genes and meaning it never even made it to the egg that offered up the other half. This is chaos theory in action, but it illustrates a point; for the universe to have ended up the way it has depends on history having played out exactly as it has done.

The classic example of this in quantum physics is the famous ‘Schrodinger’s Cat’ experiment, in which a theoretical cat was put into a box with a special quantum device that had a 50/50 chance of either doing nothing or releasing a toxic gas that would kill the cat. Schrodinger’s point was that, when the cat is put into the box, two universes emerge; one in which the cat is dead, and one in which it is alive. Until we open the box, we cannot known which of these universes we are in, so the cat must be thought of as simultaneously alive and dead.

However, another thought experiment known as the ‘quantum suicide’ experiment takes the cat’s point of view; imagine that the cat is an experimenter, and that he is working alone. Imagine you are that experimenter, and that you had stayed in the box for five iterations of the 50/50 life/death random event. In 31 out of 32 possible futures, you would have been gassed, for at least once the device would have selected the ‘death’ option; but in just one of these 32 alternative futures, you would still be alive. Moreover, if you had since got out of the box and published your results, the existence of those results is solely dependent on you being that lucky one out of 32.

Or, to put it another way, consider a generic action hero, in the classic scene where he runs through the battlefield gunning down enemies whilst other, lesser soldiers fall about him from bullets and explosions. The enemy fire countless shots at him, but try as they might they can never kill him. They try, but he survives and the film reaches its triumphant conclusion.

Now, assuming that these enemies are not deliberately trying to miss him and can at least vaguely use their weapons, if our action hero tried to pull that ‘running through a hail of bullets’ stunt then 999 times out of a thousand he’d be killed. However, if he was killed then the film would not be able to reach its conclusion, since he would be unable to save the heroine/defeat the baddie/deliver a cliched one-liner, and as such the story would be incomplete.  And, with such a crappy story, there’s no way that a film would get made about it; therefore, the action hero must always be one of the lucky ones.

This idea of always triumphing over the odds, of surviving no matter what because, if you didn’t, you wouldn’t be around to tell the tale or even be conscious of the tale, is known as quantum immortality. And whilst it doesn’t mean you’re going to be safe jumping off buildings any time soon, it does at least give yo a way to bore the pants off the next person who claims that action movies are WAAYYYY too unrealistic.

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SCIENCE!

One book that I always feel like I should understand better than I do (it’s the mechanics concerning light cones that stretch my ability to visualise) is Professor Stephen Hawking’s ‘A Brief History of Time’. The content is roughly what nowadays a Physics or Astronomy student would learn in first year cosmology, but when it was first released the content was close to the cutting edge of modern physics. It is a testament to the great charm of Hawking’s writing, as well as his ability to sell it, that the book has since sold millions of copies, and that Hawking himself is the most famous scientist of our age.

The reason I bring it up now is because of one passage from it that spring to mind the other day (I haven’t read it in over a year, but my brain works like that). In this extract, Hawking claims that some 500 years ago, it would be possible for a (presumably rich, intelligent, well-educated and well-travelled) man to learn everything there was to know about science and technology in his age. This is, when one thinks about it, a rather bold claim, considering the vast scope of what ‘science’ covers- even five centuries ago this would have included medicine, biology, astronomy, alchemy (chemistry not having been really invented), metallurgy and materials, every conceivable branch of engineering from agricultural to mining, and the early frontrunners of physics to name but some. To discover everything would have been quite some task, but I don’t think an entirely impossible one, and Hawking’s point stands: back then, there wasn’t all that much ‘science’ around.

And now look at it. Someone with an especially good memory could perhaps memorise the contents of a year’s worth of New Scientist, or perhaps even a few years of back issues if they were some kind of super-savant with far too much free time on their hands… and they still would have barely scratched the surface. In the last few centuries, and particularly the last hundred or so years, humanity’s collective march of science has been inexorable- we have discovered neurology, psychology, electricity, cosmology, atoms and further subatomic particles, all of modern chemistry, several million new species, the ability to classify species at all, more medicinal and engineering innovations than you could shake a stick at, plastics, composites and carbon nanotubes, palaeontology, relativity, genomes, and even the speed of spontaneous combustion of a burrito (why? well why the f&%$ not?). Yeah, we’ve come a long way.

The basis for all this change occurred during the scientific revolution of the 16th and 17th centuries. The precise cause of this change somewhat unknown- there was no great upheaval, but more of a general feeling that ‘hey, science is great, let’s do something with it!’. Some would argue that the idea that there was any change in the pace of science itself is untrue, and that the groundwork for this period of advancing scientific knowledge was largely done by Muslim astronomers and mathematicians several centuries earlier. Others may say that the increasing political and social changes that came with the Renaissance not only sent society reeling slightly, rendering it more pliable to new ideas and boundary-pushing, but also changed the way that the rich and noble functioned. Instead of barons, dukes and the nobility simply resting on their laurels and raking in the cash as the feudal system had previously allowed them to, an increasing number of them began to contribute to the arts and sciences, becoming agents of change and, in the cases of some, agents in the advancement of science.

It took a long time for science to gain any real momentum. For many a decade, nobody was ever a professional scientist or even engineer, and would generally study in their spare time. Universities were typically run by monks and populated by the sons of the rich or the younger sons of nobles- they were places where you both lived and learned expensively, but were not the centres of research that they are nowadays. They also contained a huge degree of resistance to the ideas put forward by Aristotle and others that had been rediscovered at the start of the revolution, and as such trying to get one’s new ideas taken seriously was a severe task. As such, just as many scientists were merely people who were interested in a subject and rich and intelligent enough to dabble in it as they were people committed to learning. Then there was the notorious religious problem- whilst the Church had no problem with most scientific endeavours, the rise of astronomy began one long and ceaseless feud between the Pope and physics into the fallibility of the bible, and some, such as Galileo and Copernicus, were actively persecuted by the Church for their new claims. Some were even hanged. But by far the biggest stumbling block was the sheer number of potential students of science- most common people were peasants, who would generally work the land at their lord’s will, and had zero chance of gravitating their life prospects higher than that. So- there was hardly anyone to do it, it was really, really hard to make any progress in and you might get killed for trying. And yet, somehow, science just kept on rolling onwards. A new theory here, an interesting experiment here, the odd interesting conversation between intellectuals, and new stuff kept turning up. No huge amount, but it was enough to keep things ticking over.

But, as the industrial revolution swept Europe, things started to change. As revolutions came and went, the power of the people started to rise, slowly squeezing out the influence and control of aristocrats by sheer weight of numbers. Power moved from the monarchy to the masses, from the Lords to the Commons- those with real control were the entrepreneurs and factory owners, not old men sitting in country houses with steadily shrinking lands that they owned. Society began to become more fluid, and anyone (well, more people than previously, anyway), could become the next big fish by inventing something new. Technology began to become of ever-increasing importance, and as such so did its discovery. Research by experiment was ever-more accessible, and science began to gather speed. During the 20th century things really began to motor- two world wars prompted the search for new technologies to enter an even more frenzied pace, the universal schooling of children was breeding a new generation of thinkers, and the idea of a university as a place of learning and research became more cemented in popular culture. Anyone could think of something new, and in that respect everyone was a scientist.

And this, to me, is the key to the world we live in today- a world in which a dozen or so scientific papers are published every day for branches of science relevant largely for their own sake. But this isn’t the true success story of science. The real success lies in the products and concepts we see every day- the iPhone, the pharmaceuticals, the infrastructure. The development of none of these discovered a new effect, a new material, or enabled us to better understand the way our thyroid gland works, and in that respect they are not science- but they required someone to think a little bit, to perhaps try a different way of doing something, to face a challenge. They pushed us forward one, tiny inexorable step, put a little bit more knowledge into the human race, and that, really, is the secret. There are 7 billion of us on this planet right now. Imagine if every single one contributed just one step forward.

Time is a funny old thing…

Today I am rather short on time- the work I have to do is beginning to mount up despite (and partially because) of a long weekend. To most people this is a perfectly good reason to put up an apologetic cop-out of a post to prevent them having to work on it, but for me, it is a perfectly good excuse for my bloodymindedness to take over, so I thought I might write something about time.
As such a strange and almost abstract concept as it is, time can be viewed from a number of perspectives- the physical sense, the thermodynamic sense, and the human sense are the three obvious ones that spring to mind. To a physicist, time is a dimension much like width and length, and is far from unique- in fact there is a large sector of theoretical physics open to the idea that in the big bang there were many millions of dimensions, only 4 of which (3 spacial and one temporal) opened up into the rest of the universe, the other dimensions only existing on a microscopic, atomic scale (which might explain why the quantum world is so plain weird. Hey- I’m no physicist, and the web can probably tell you more). The really special thing about time compared to spacial dimensions to a physicist (among a long list, that are confusing and difficult to describe), is that it is the only dimension with an obvious direction. People often talk of ‘the arrow of time’, but the idea of any other dimension having an arrow is only a sort of arbitrary point of reference (north & south, up & down are only relative to our own earth and so are merely convenient reference points. This idea of time having an irreversible arrow annoys a lot of physicists as there appears to be little, fundamentally, that means we couldn’t travel in time in the other direction- the theory of relativity, for example, shows how fluid time can be. The idea of time’s direction has a lot to do with thermodynamics, which is where the second perspective of time comes from.
Really I am using the word thermodynamic very loosely, as what I am really thinking of is more to do with the psychological arrow of time. To quickly paraphrase what I mean by thermodynamics, the second law of thermodynamics states that the universe’s level of entropy, or randomness, will always increase or stay the same, never decrease, because a more random, chaotic system is more stable. One way of thinking of this is like a beach- the large swathes of sand can be arranged in a huge number of configurations and still seem the same, but if there are lots of sandcastles over it, there is a lot less randomness. One can seemingly reverse this process by building more sandcastles, making the universe more ordered, but to do this requires energy which, on a universal level, increases the universe’s entropic level. It is for this reason that a smashed pot will always have been preceded, but not followed by, the same pot all in one piece.
The thing is, the psychological and thermodynamic arrows of time point in the same direction, and their link on one another is integral. Our whole view of the passing of time is influenced by the idea of events that have irrevocably ‘happened’ and are ‘over’, hence our eternal fascination with ‘what if’s’. We persistently worry about past mistakes, what could have been, and what things were like, but never can be- hence the popularity of historical stories, ruins, nostalgia and grumbling about teenagers. For a better explanation of the various ‘arrows of time’, try Stephen Hawking’s ‘A Brief History of Time’- it is somewhat out of date now and it is fashionable now to think of it as overly simplistic, but it’s still a good source of a grounding in high-level physics
The final, and to me most interesting, perspective of time I want to talk about is deeply linked to the psychological arrow and our thoughts of the passing of time, but brings its own, uniquely relative, view- the human perspective (notice how it is always people I seem to find the most interesting.) We humans view time in a way that, when thought about, paints a weirdly fluid portrait of the behaviour of time. There is never enough time to work, too much time spent waiting, not enough time spent on holidays or relaxing, too much time spent out of work, too little time spent eating the cake and too much spent washing up. There are the awkward pauses in conversation that seem to drag on for an eternity, especially when they come just after the moment when the entire room goes silent for no accountable reason, enabling everyone to hear the most embarrassing part of your conversation. There are those hours spent doing things you love that you just gobble up, revelling in your own happiness, and the bitter, painful minutes of deep personal pain.
Popular culture and everyday life often mentions or features these weirdly human notions of time being so relative to the scenario- Albert Einstein himself described relativity thus: “When you are talking to a nice girl, an hour seems like a second. When you have your hand on a bar of red-hot iron, a second seems like an hour”. In fact, when you think about it, it is almost as if time appears to be a living thing, at least in the context of our references to it. This, I think anyway, is the nub of the matter- time is something that we encounter, in its more thermodynamic form, every day of our lives, and just like pet owners will tend to anthropomorphise their pets’ facial expressions, so the human race has personified time in general conversation (well, at least in the western world- I cannot speak for anywhere non English-speaking as a certainty). Time is almost one of the family- ever-present, ever-around, ever-referred to, until it becomes as human as a long-lost friend, in its own little way.
Finally, on the subject of time, Mr Douglas Adams: “Time is an illusion; lunchtime doubly so”