The Red Flower

Fire is, without a doubt, humanity’s oldest invention and its greatest friend; to many, the fundamental example what separates us from other animals. The abilities to keep warm through the coldest nights and harshest winters, to scare away predators by harnessing this strange force of nature, and to cook a joint of meat because screw it, it tastes better that way, are incredibly valuable ones, and they have seen us through many a tough moment. Over the centuries, fire in one form or another has been used for everything from being a weapon of war to furthering science, and very grateful we are for it too.

However, whilst the social history of fire is interesting, if I were to do a post on it then you dear readers would be faced with 1000 words of rather repetitive and somewhat boring myergh (technical term), so instead I thought I would take this opportunity to resort to my other old friend in these matters: science, as well as a few things learned from several years of very casual outdoorsmanship.

Fire is the natural product of any sufficiently exothermic reaction (ie one that gives out heat, rather than taking it in). These reactions can be of any type, but since fire can only form in air most of such reactions we are familiar with tend to be oxidation reactions; oxygen from the air bonding chemically with the substance in question (although there are exceptions;  a sample of potassium placed in water will float on the top and react with the water itself, become surrounded surrounded by a lilac flame sufficiently hot to melt it, and start fizzing violently and pushing itself around the container. A larger dose of potassium, or a more reactive alkali metal such as rubidium, will explode). The emission of heat causes a relatively gentle warming effect for the immediate area, but close to the site of the reaction itself a very large amount of heat is emitted in a small area. This excites the molecules of air close to the reaction and causes them to vibrate violently, emitting photons of electromagnetic radiation as they do so in the form of heat & light (among other things). These photons cause the air to glow brightly, creating the visible flame we can see; this large amount of thermal energy also ionises a lot of atoms and molecules in the area of the flame, meaning that a flame has a slight charge and is more conductive than the surrounding air. Because of this, flame probes are sometimes used to get rid of the excess charge in sensitive electromagnetic experiments, and flamethrowers can be made to fire lightning. Most often the glowing flame results in the characteristic reddy/orange colour of fire, but some reactions, such as the potassium one mentioned, cause them to emit radiation of other frequencies for a variety of reasons (chief among them the temperature of the flame and the spectral properties of the material in question), causing the flames to be of different colours, whilst a white-hot area of a fire is so hot that the molecules don’t care what frequency the photons they’re emitting are at so long as they can get rid of the things fast enough. Thus, light of all wavelengths gets emitted, and we see white light. The flickery nature of a flame is generally caused by the excited hot air moving about rapidly, until it gets far enough away from the source of heat to cool down and stop glowing; this process happens all the time with hundreds of packets of hot air, causing them to flicker back and forth.

However, we must remember that fires do not just give out heat, but must take some in too. This is to do with the way the chemical reaction to generate the heat in question works; the process requires the bonds between atoms to be broken, which uses up energy, before they can be reformed into a different pattern to release energy, and the energy needed to break the bonds and get the reaction going is known as the activation energy. Getting the molecules of the stuff you’re trying to react to the activation energy is the really hard part of lighting a fire, and different reactions (involving the burning of different stuff) have different activation energies, and thus different ‘ignition temperatures’ for the materials involved. Paper, for example, famously has an ignition temperature of 451 Fahrenheit (which means, incidentally, that you can cook with it if you’re sufficiently careful and not in a hurry to eat), whilst wood’s is only a little higher at around 300 degrees centigrade, both of which are less than that of a spark or flame. However, we must remember that neither fuel will ignite if it is wet, as water is not a fuel that can be burnt, meaning that it often takes a while to dry wood out sufficiently for it to catch, and that big, solid blocks of wood take quite a bit of energy to heat up.

From all of this information we can extrapolate the first rule that everybody learns about firelighting; that in order to catch a fire needs air, dry fuel and heat (the air provides the oxygen, the fuel the stuff it reacts with and the heat the activation energy). When one of these is lacking, one must make up for it by providing an excess of at least one of the other two, whilst remembering not to let the provision of the other ingredients suffer; it does no good, for example, to throw tons of fuel onto a new, small fire since it will snuff out its access to the air and put the fire out. Whilst fuel and air are usually relatively easy to come by when starting a fire, heat is always the tricky thing; matches are short lived, sparks even more so, and the fact that most of your fuel is likely to be damp makes the job even harder.

Provision of heat is also the main reason behind all of our classical methods of putting a fire out; covering it with cold water cuts it off from both heat and oxygen, and whilst blowing on a fire will provide it with more oxygen, it will also blow away the warm air close to the fire and replace it with cold, causing small flames like candles to be snuffed out (it is for this reason that a fire should be blown on very gently if you are trying to get it to catch and also why doing so will cause the flames, which are caused by hot air remember, to disappear but the embers to glow more brightly and burn with renewed vigour once you have stopped blowing).  Once a fire has sufficient heat, it is almost impossible to put out and blowing on it will only provide it with more oxygen and cause it to burn faster, as was ably demonstrated during the Great Fire of London. I myself have once, with a few friends, laid a fire that burned for 11 hours straight; many times it was reduced to a few humble embers, but it was so hot that all we had to do was throw another log on it and it would instantly begin to burn again. When the time came to put it out, it took half an hour for the embers to dim their glow.

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Why the chubs?

My last post dealt with the thorny issue of obesity, both it’s increasing presence in our everyday lives, and what for me is the underlying reason behind the stats that back up media scare stories concerning ‘the obesity epidemic’- the rise in size of the ‘average’ person over the last few decades. The precise causes of this trend can be put down to a whole host of societal factors within our modern age, but that story is boring as hell and has been repeated countless times by commenters far more adept in this field than me. Instead, today I wish present the case for modern-day obesity as a problem concerning the fundamental biology of a human being.

We, and our dim and distant ancestors of the scaly/furry variety, have spent the last few million years living wild; hunting, fighting and generally acting much like any other evolutionary pathway. Thus, we can learn a lot about our own inbuilt biology and instincts by studying the behaviour of animals currently alive today, and when we do so, several interesting animal eating habits become apparent. As anyone who has tried it as a child can attest (and I speak from personal experience), grass is not good stuff to eat. It’s tough, it takes a lot of chewing and processing (many herbivores have multiple stomachs to make sure they squeeze the maximum nutritional value out of their food), and there really isn’t much of it to power a fully-functional being. As such, grazers on grass and other such tough plant matter (such as leaves) will spend most of their lives doing nothing but guzzle the stuff, trying to get as much as possible through their system. Other animals will favour food with a higher nutritional content, such as fruits, tubers or, in many cases, meat, but these frequently present issues. Fruits are highly seasonal and rarely available in a large enough volume to support a large population, as well as being quite hard to get a lot of down; plants try to ‘design’ fruits so that each visitor takes only a few at a time, so as best to spread their seeds far and wide, and as such there are few animals that can sustain themselves on such a diet.  Other food such as tubers or nuts are hard to get at, needing to be dug up or broken in highly energy-consuming activities, whilst meat has the annoying habit of running away or fighting back whenever you try to get at it. As anyone who watches nature documentaries will attest, most large predators will only eat once every few days (admittedly rather heavily).

The unifying factor of all of this is that food is, in the wild, highly energy- and time-consuming to get hold of and consume, since every source of it guards its prize jealously. Therefore, any animal that wants to survive in this tough world must be near-constantly in pursuit of food simply to fulfil all of its life functions, and this is characterised by being perpetually hungry. Hunger is a body’s way of telling us that we should get more food, and in the wild this constant desire for more is kept in check by the difficulty that getting hold of it entails. Similarly, animal bodies try to assuage this desire by being lazy; if something isn’t necessary, then there’s no point wasting valuable energy going after it (since this will mean spending more time going after food to replace lost energy.)

However, in recent history (and a spectacularly short period of time from evolution’s point of view), one particular species called homo sapiens came up with this great idea called civilisation, which basically entailed the pooling and sharing of skill and resources in order to best benefit everyone as a whole. As an evolutionary success story, this is right up there with developing multicellular body structures in terms of being awesome, and it has enabled us humans to live far more comfortable lives than our ancestors did, with correspondingly far greater access to food. This has proved particularly true over the last two centuries, as technological advances in a more democratic society have improved the everyman’s access to food and comfortable living to a truly astounding degree. Unfortunately (from the point of view of our waistline) the instincts of our bodies haven’t quite caught up to the idea that when we want/need food, we can just get food, without all that inconvenient running around after it to get in the way. Not only that, but a lack of pack hierarchy combined with this increased availability means that we can stock up on food until we have eaten our absolute fill if so we wish; the difference between ‘satiated’ and ‘stuffed’ can work out as well over 1000 calories per meal, and over a long period of time it only takes a little more than we should be having every day to start packing on the pounds. Combine that with our natural predilection to laziness meaning that we don’t naturally think of going out for some exercise as fun purely for its own sake, and the fact that we no longer burn calories chasing our food, or in the muscles we build up from said chasing, and we find ourselves consuming a lot more calories than we really should be.

Not only that, but during this time we have also got into the habit of spending a lot of time worrying over the taste and texture of our food. This means that, unlike our ancestors who were just fine with simply jumping on a squirrel and devouring the thing, we have to go through the whole rigmarole of getting stuff out of the fridge, spending two hours slaving away in a kitchen and attempting to cook something vaguely resembling tasty. This wait is not something out bodies enjoy very much, meaning we often turn to ‘quick fixes’ when in need of food; stuff like bread, pasta or ready meals. Whilst we all know how much crap goes into ready meals (which should, as a rule, never be bought by anyone who cares even in the slightest about their health; salt content of those things is insane) and other such ‘quick fixes’, fewer people are aware of the impact a high intake of whole grains can have on our bodies. Stuff like bread and rice only started being eaten by humans a few thousand years ago, as we discovered the benefits of farming and cooking, and whilst they are undoubtedly a good food source (and are very, very difficult to cut from one’s diet whilst still remaining healthy) our bodies have simply not had enough time, evolutionarily speaking, to get used to them. This means they have a tendency to not make us feel as full as their calorie content should suggest, thus meaning that we eat more than our body in fact needs (if you want to feel full whilst not taking in so many calories, protein is the way to go; meat, fish and dairy are great for this).

This is all rather academic, but what does it mean for you if you want to lose a bit of weight? I am no expert on this, but then again neither are most of the people acting as self-proclaimed nutritionists in the general media, and anyway, I don’t have any better ideas for posts. So, look at my next post for my, admittedly basic, advice for anyone trying to make themselves that little bit healthier, especially if you’re trying to work of a few of the pounds built up over this festive season.

The Pursuit of Speed

Recent human history has, as Jeremy Clarkson constantly loves to point out, been dominated by the pursuit of speed. Everywhere we look, we see people hurrying hither and thither, sprinting down escalators, transmitting data at next to lightspeed via their phones and computers, and screaming down the motorway at over a hundred kilometres an hour (or nearly 100mph if you’re the kind of person who habitually uses the fast lane of British motorways). Never is this more apparent than when you consider our pursuit of a new maximum, top speed, something that has, over the centuries, got ever higher and faster. Even in today’s world, where we prize speed of information over speed of movement, this quest goes on, as evidenced by the team behind the ‘Bloodhound’ SSC, tipped to break the world land speed record. So, I thought I might take this opportunity to consider the history of our quest for speed, and see how it has developed over time.

(I will ignore all unmanned human exploits for now, just so I don’t get tangled up in arguments concerning why a satellite may be considered versus something out of the Large Hadron Collider)

Way back when we humans first evolved into the upright, bipedal creatures we are now, we were a fairly primitive race and our top speed was limited by how fast we could run.  Usain Bolt can, with the aid of modern shoes, running tracks and a hundred thousand people screaming his name, max out at around 13 metres per second. We will therefore presume that a fast human in prehistoric times, running on bare feet, hard ground, and the motivation of being chased by a lion, might hit 11m/s, or 43.2 kilometres per hour. Thus our top speed remained for many thousands of years, until, around 6000 years ago, humankind discovered how to domesticate animals, and more specifically horses, in the Eurasian Steppe. This sent our maximum speed soaring to 70km/h or more, a speed that was for the first time sustainable over long distances, especially on the steppe where horses where rarely asked to tow or carry much. Thus things remained for another goodly length of time- in fact, many leading doctors were of the opinion that travelling any faster would be impossible to do without asphyxiating. However, come the industrial revolution, things started to change, and records began tumbling again. The train was invented in the 1800s and quickly transformed from a slow, lumbering beast into a fast, sleek machine capable of hitherto unimaginable speed. In 1848, the Iron Horse took the land speed record away from its flesh and blood cousin, when a train in Boston finally broke the magical 60mph (ie a mile a minute) barrier to send the record shooting up to 96.6 km/h. Records continued to tumble for the next half-century, breaking the 100 mph barrier by 1904, but by then there was a new challenger on the paddock- the car. Whilst early wheel-driven speed records had barely dipped over 35mph, after the turn of the century they really started to pick up the pace. By 1906, they too had broken the 100mph mark, hitting 205km/h in a steam-powered vehicle that laid the locomotives’ claims to speed dominance firmly to bed. However, this was destined to be the car’s only ever outright speed record, and the last one to be set on the ground- by 1924 they had got up to 234km/h, a record that stands to this day as the fastest ever recorded on a public road, but the First World War had by this time been and gone, bringing with it a huge advancement in aircraft technology. In 1920, the record was officially broken in the first post-war attempt, a French pilot clocking 275km/h, and after that there was no stopping it. Records were being broken left, right and centre throughout both the Roaring Twenties and the Great Depression, right up until the breakout of another war in 1939. As during WWI, all records ceased to be officiated for the war’s duration, but, just as the First World War allowed the plane to take over from the car as the top dog in terms of pure speed, so the Second marked the passing of the propellor-driven plane and the coming of the jet & rocket engine. Jet aircraft broke man’s top speed record just 5 times after the war, holding the crown for a total of less than two years, before they gave it up for good and let rockets lead the way.

The passage of records for rocket-propelled craft is hard to track, but Chuck Yeager in 1947 became the first man ever to break the sound barrier in controlled, level flight (plunging screaming to one’s death in a deathly fireball apparently doesn’t count for record purposes), thanks not only to his Bell X-1’s rocket engine but also the realisation that breaking the sound barrier would not tear the wings of so long as they were slanted back at an angle (hence why all jet fighters adopt this design today). By 1953, Yeager was at it again, reaching Mach 2.44 (2608km/h) in the X-1’s cousing, the X-1A. The process, however, nearly killed him when he tilted the craft to try and lose height and prepare to land, at which point a hitherto undiscovered phenomenon known as ‘inertia coupling’ sent the craft spinning wildly out of control and putting Yeager through 8G’s of force before he was able to regain control. The X-1’s successor, the X-2, was even more dangerous- despite pushing the record up to first 3050km/h  one craft exploded and killed its pilot in 1953, before a world record-breaking flight reaching Mach 3.2 (3370 km/h), ended in tragedy when a banking turn at over Mach 3 sent it into another inertia coupling spin that resulted, after an emergency ejection that either crippled or killed him, in the death of pilot Milburn G. Apt. All high-speed research aircraft programs were suspended for another three years, until experiments began with the Bell X-15, the latest and most experimental of these craft. It broke the record 5 times between 1961 and 67, routinely flying above 6000km/h, before another fatal crash, this time concerning pilot Major Michael J Adams in a hypersonic spin, put paid to the program again, and the X-15’s all-time record of 7273km/h remains the fastest for a manned aircraft. But it still doesn’t take the overall title, because during the late 60s the US had another thing on its mind- space.

Astonishingly, manned spacecraft have broken humanity’s top speed record only once, when the Apollo 10 crew achieved the fastest speed to date ever achieved by human beings relative to Earth. It is true that their May 1969 flight did totally smash it, reaching 39 896km/h on their return to earth, but all subsequent space flights, mainly due to having larger modules with greater air resistance, have yet to top this speed. Whether we ever will or not, especially given today’s focus on unmanned probes and the like, is unknown. But people, some brutal abuse of physics is your friend today. Plot all of these records on a graph and add a trendline (OK you might have to get rid of the horse/running ones and fiddle with some numbers), and you have a simple equation for the speed record against time. This can tell us a number of things, but one is of particular interest- that, statistically, we will have a man travelling at the speed of light in 2177. Star Trek fans, get started on that warp drive…