Gravity

At time of writing, I’ve just come home from watching Gravity, Alfonso Cuaron’s recent space-set thriller. And my immediate reaction can be essentially summed up in three words: holy f***ing shit.

OK, OK, I’ll fill in a bit; if you weren’t already aware, Gravity tells the story of a space shuttle mission gone disastrously wrong whilst in orbit, leaving just two survivors: George Clooney playing essentially a spacegoing version of himself as the suave, talkative veteran Matt Kowalski and Sandra Bullock as the inexperienced, depressive and perpetually scared Dr. Ryan Stone. With their craft destroyed, both are faced with the daunting prospect of trying to return to earth alive- without the luxuries of a ship, communications, equipment or much ability to control their own movements. And that’s all I can really say without giving away spoilers- indeed, I feel like the rest of this review may end up giving away a fair few details. However, since the main thrust of what makes the film such an experience is not contained within its plot, so unless you have a burning desire to see Gravity completely unspoiled you’re probably not going to lose out on much by reading on.

The result is something pretty amazing, but Gravity is not flawless by any means- I doubt any film ever was. I don’t know whether the story of former astronaut Commander Chris Hadfield getting thrown out of a Canadian cinema for shouting about the film’s inaccuracies at the screen is true or not, but if so I can see where he’d have been coming from- I am no astronaut, but I know enough about space to say that communications and spy satellites operate at completely different altitudes, neither of which are in the range depicted by the film, and that during re-entry there should not be random objects floating around the cabin like it’s in zero-g. Those are only the more obvious errors- the film does a grand job of delivering the general gist of a spacial environment, but had I so wished I could have spent the entire film pointing out minor inaccuracies or inconsistencies. But then again, I’m no astronaut- and besides, Gravity is hardly the only film to take some rather serious liberties with the laws of physics.

It’s not only in terms of its scientific accuracy where the film has flaws. Its characterisation is almost non-existent, the plot is as stripped-down and oversimplified as it could possibly be whilst still existing, multiple story elements seem decidedly contrived and the whole thing has precisely zero thematic complexity between the tried & tested ‘indomitable human spirit’ arc. But that’s all kinda the point. Gravity is not an actor’s film, nor indeed a writer’s- indeed I have a sneaking suspicion that Cuaron may simply have done three days filming, then locked himself in  a room with his cinematographer and CGI person for a few months putting together the rest of it. The result is nothing less than a jaw-dropping spectacle of a film, something genuinely amazing: to be honest, I’m not even sure that’s even a compliment. It feels more like a simple description of the film’s nature- even if this had been the background setting for something written by Ed Wood, the sheer amazement factor of how the film presents itself would still have left me sitting back in my seat mouth open like a goon.

I mean, just consider the visuals. Alone, they would be enough to make watching Gravity a special experience, capturing as they do both the scale and beauty of the view from space alongside the strange unreality that is sitting in a tin can hurtling at unimaginable speed thousands of kilometres above the surface of our mother earth. The film’s extensive use of CGI (because seriously, how else do you create an action set piece around a ****ing space station) is noticeable, but by keeping the visual style very consistent the film avoids drawing attention to it and maintains a highly immersive experience. Then there’s the cinematography; from the early outset Gravity sets a baseline for weirdness and confusion as a constantly moving, rotating camera reminds us of the nature of space, and the total lack of a reference frame that one has in it. There is no up or down- there is only ‘over there’, and when ‘over there’ is flying around madly as you tumble uncontrollably towards it, as happens frequently during the action set pieces, the whole thing gets decidedly disorientating. I’m rather glad I don’t get motion sick, or indeed scared of heights once the film decides to point out that space flight is, in fact, nothing more than falling very, very quickly.

But what makes Gravity really work is how it creates an atmosphere. The whole thing seems specifically designed to make space seem as utterly, utterly terrifying on all levels to make our hero’s struggle seem that much more daunting and amazing, and the film pulls off on that spectacularly. A key part of its toolbox is its use of thematic contrast: the huge, jaw-dropping visual spectacles that are the action sequences keep the danger and blind terror foremost in our mind, but are offset by the near-silent intimate moments that both give the audience time to process the beautiful insanity playing out in front of them and to remind us all that, surrounded by airless wilderness, ‘in space, nobody can hear you scream’. Cuaron deserves particular credit for his use of music in this regard- it’s one of those things you almost don’t notice, but every set piece is built up slowly, cranking up the tension, before launching into a booming orchestral inferno of noise as the action gets into full flow. And then- silence, save for our protagonist’s terrified breathing. I don’t think any film has ever made me feel a character’s emotion quite so much, and certainly none has done so to a faceless spacesuit.

Ultimately, I’m not sure me spouting words can really do the film justice- it’s one of those things where I could describe the entire storyline, down to the last scene, and it’d still be the barest shadow of what viewing the film in all its glory is. Just let me put it this way: Gravity is an hour and a half of watching people falling out of the sky through the most hostile environment in the universe amidst a chaotic firestorm of broken metal and machinery. And it is every bit as terrifying, jaw-dropping and downright awe-inspiring as that sounds.

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Shining Curtains

When the Vikings swept across Europe in the 7th and 8th centuries, they brought with them many stories; stories of their Gods, of the birth of the world, of Asgard, of Valhalla, of Jormundur the world-serpent, of Loki the trickster, Odin the father and of Ragnarok- the end of this world and the beginning of the next. However, the reason I mention the Vikings today is in reference to one particular set of stories they brought with them; of shining curtains of brilliant, heavenly fire, dancing across the northern sky as the Gods fought with one another. Such lights were not common in Europe, but they were certainly known, and throughout history have provoked terror at the anger of the various Gods that was clearly being displayed across the heavens. Now, we know these shining curtains as the aurora borealis (Aurora was the Roman goddess of the dawn, whilst boreas was the Greek name for the north wind (because the aurora was only observed in the far north- a similar feature known as the aurora australis is seen near the south pole). The name was acquired in 1621).

Nowadays, we know that the auroras are an electromagnetic effect, which was demonstrated quite spectacularly in 1859. On the 28th of August and 2nd of September that year, spectacular auroras erupted across much of the northern hemisphere, reaching their peak at one o’clock in the morning EST, and as far south as Boston the light was enough to read by. However, the feature I am interested here concerns the American Telegraph Line, stretching almost due north between Boston, Massachusetts, and Portland, Maine. Because of the great length and orientation of this line, the electromagnetic field generated by the aurora was sufficient to induce a current in the telegraph, to the extent that operators at both ends of the line communicated to decide to switch off their batteries (which were only interfering) and operate solely on aurora-power for around two hours. Aside from a gentle fluctuation of current, no problems were reported with this system.

We now know that the ultimate cause of the aurorae is our sun, and that two loads of exceptional solar activity were responsible for the 1859 aurora. We all know the sun emits a great deal of energy from the nuclear fusion going on in its core, but it also emits a whole lot of other stuff; including a lot of ionised (charged) gas, or plasma. This outflow of charged particles forms what is known as the solar wind, flowing out into space in all directions; it is this solar wind that generates the tail on comets, and is why such a tail always points directly away from the sun. However, things get interesting when the solar wind hits a planet such as Earth, which has a magnetic field surrounding it. Earth’s magnetic field looks remarkably similar to that of a large, three-dimensional bar magnet (this picture demonstrates it’s shape well), and when a large amount of charged particles passes through this magnetic field it is subject to something known as the motor effect. As every GCSE physics student knows, it is this effect that allows us to generate motion from electricity, and the same thing happens here; the large mass of moving charge acts as a current, and this cuts across the earth’s magnetic field. This generates a force (this is basically what the motor effect does), and this force points sideways, pushing the solar wind sideways. However, as it moves, so does the direction of the ‘current’, and thus the direction of the force changes too; this process ends up causing the charge to spin around the magnetic field lines of the earth, causing it to spiral as this mass of charged particles moves along them. Following these field lines, the charge will end up spiralling towards the poles of the earth, at which point the field lines bend and start going into the earth itself. As the plasma follows these lines therefore, it will come into contact with the Earth’s atmosphere, and one section of it in particular; the magnetosphere.

The magnetosphere is a region of our atmosphere that covers the upper level of our ionosphere which has a strong magnetic field. Here, the magnetic fields of both the charged plasma and the magnetosphere itself combine in a rather complicated process known as magnetic reconnection, the importance of which will be discussed later. Now, let us consider the contents of the plasma, all these charged particles and in particular high energy electrons that are now bumping into atoms of air in the ionosphere. This bumping into atoms gives them energy, which an atom deals with by having electrons within the atoms jump up energy levels and enter an excited state. After a short while, the atoms ‘cool down’ by having electrons drop down energy levels again, releasing packets of electromagnetic energy as they do so. We observe this release of EM radiation as visible light, and hey presto! we can see the aurorae. What colour the aurora ends up being depends on what atoms we are interacting with; oxygen is more common higher up and generates green and red aurorae depending on height, so these are the most common colours. If the solar wind is able to get further down in the atmosphere, it can interact with nitrogen and produce blue and purple aurorae.

The shape of the aurorae can be put down to the whole business of spiralling around field lines; this causes, as the field lines bend in towards the earth’s poles, them to describe roughly circular paths around the north and south poles. However, plasma does not conduct electricity very well between magnetic field lines, as this pattern is, so we would not expect the aurora to be very bright under normal circumstances. The reason this is not the case, and that aurorae are as visible and beautiful as they are, can be put down to the process of magnetic reconnection, which makes the plasma more conductive and allows these charged particles to flow more easily around in a circular path. This circular path around the poles causes the aurora to follow approximately east-west lines into the far distance, and thus we get the effect of ‘curtains’ of light following (roughly) this east-west pattern. The flickery, wavy nature of these aurora is, I presume, due to fluctuations in the solar wind and/or actual winds in the upper atmosphere. The end result? Possibly the most beautiful show Earth has to offer us. I love science.

Practical computing

This looks set to be my final post of this series about the history and functional mechanics of computers. Today I want to get onto the nuts & bolts of computer programming and interaction, the sort of thing you might learn as a budding amateur wanting to figure out how to mess around with these things, and who’s interested in exactly how they work (bear in mind that I am not one of these people and am, therefore, likely to get quite a bit of this wrong). So, to summarise what I’ve said in the last two posts (and to fill in a couple of gaps): silicon chips are massive piles of tiny electronic switches, memory is stored in tiny circuits that are either off or on, this pattern of off and on can be used to represent information in memory, memory stores data and instructions for the CPU, the CPU has no actual ability to do anything but automatically delegates through the structure of its transistors to the areas that do, the arithmetic logic unit is a dumb counting machine used to do all the grunt work and is also responsible, through the CPU, for telling the screen how to make the appropriate pretty pictures.

OK? Good, we can get on then.

Programming languages are a way of translating the medium of computer information and instruction (binary data) into our medium of the same: words and language. Obviously, computers do not understand that the buttons we press on our screen have symbols on them, that these symbols mean something to us and that they are so built to produce the same symbols on the monitor when we press them, but we humans do and that makes computers actually usable for 99.99% of the world population. When a programmer brings up an appropriate program and starts typing instructions into it, at the time of typing their words mean absolutely nothing. The key thing is what happens when their data is committed to memory, for here the program concerned kicks in.

The key feature that defines a programming language is not the language itself, but the interface that converts words to instructions. Built into the workings of each is a list of ‘words’ in binary, each word having a corresponding, but entirely different, string of data associated with it that represents the appropriate set of ‘ons and offs’ that will get a computer to perform the correct task. This works in one of two ways: an ‘interpreter’ is an inbuilt system whereby the programming is stored just as words and is then converted to ‘machine code’ by the interpreter as it is accessed from memory, but the most common form is to use a compiler. This basically means that once you have finished writing your program, you hit a button to tell the computer to ‘compile’ your written code into an executable program in data form. This allows you to delete the written file afterwards, makes programs run faster, and gives programmers an excuse to bum around all the time (I refer you here)

That is, basically how computer programs work- but there is one last, key feature, in the workings of a modern computer, one that has divided both nerds and laymen alike across the years and decades and to this day provokes furious debate: the operating system.

An OS, something like Windows (Microsoft), OS X (Apple) or Linux (nerds), is basically the software that enables the CPU to do its job of managing processes and applications. Think of it this way: whilst the CPU might put two inputs through a logic gate and send an output to a program, it is the operating system that will set it up to determine exactly which gate to put it through and exactly how that program will execute. Operating systems are written onto the hard drive, and can, theoretically, be written using nothing more than a magnetized needle, a lot of time and a plethora of expertise to flip the magnetically charged ‘bits’ on the hard disk. They consist of many different parts, but the key feature of all of them is the kernel, the part that manages the memory, optimises the CPU performance and translates programs from memory to screen. The precise translation and method by which this latter function happens differs from OS to OS, hence why a program written for Windows won’t work on a Mac, and why Android (Linux-powered) smartphones couldn’t run iPhone (iOS) apps even if they could access the store. It is also the cause of all the debate between advocates of different operating systems, since different translation methods prioritise/are better at dealing with different things, work with varying degrees of efficiency and are more  or less vulnerable to virus attack. However, perhaps the most vital things that modern OS’s do on our home computers is the stuff that, at first glance seems secondary- moving stuff around and scheduling. A CPU cannot process more than one task at once, meaning that it should not be theoretically possible for a computer to multi-task; the sheer concept of playing minesweeper whilst waiting for the rest of the computer to boot up and sort itself out would be just too outlandish for words. However, a clever piece of software called a scheduler in each OS which switches from process to process very rapidly (remember computers run so fast that they can count to a billion, one by one, in under a second) to give the impression of it all happening simultaneously. Similarly, a kernel will allocate areas of empty memory for a given program to store its temporary information and run on, but may also shift some rarely-accessed memory from RAM (where it is accessible) to hard disk (where it isn’t) to free up more space (this is how computers with very little free memory space run programs, and the time taken to do this for large amounts of data is why they run so slowly) and must cope when a program needs to access data from another part of the computer that has not been specifically allocated a part of that program.

If I knew what I was talking about, I could witter on all day about the functioning of operating systems and the vast array of headache-causing practicalities and features that any OS programmer must consider, but I don’t and as such won’t. Instead, I will simply sit back, pat myself on the back for having actually got around to researching and (after a fashion) understanding all this, and marvel at what strange, confusing, brilliant inventions computers are.