## Dwelling in the past

Some accounts have the wizard Merlin living his life from future to past, in the opposite direction to the rest of us. This meant that to him, what would a final farewell to us would be a joyous first meeting for him, and a first meeting would a sad goodbye. He remembered the future, but the past was a complete mystery to him.

The trolls in Terry Pratchett’s Diskworld had similar ideas. They considered that they travelled through time from past to future, as is normally understood, but they also considered that we were facing backwards in time as we travelled through it. This was conjectured by the trolls, to explain the fact that we can see where we are going when we travel in whatever direction we choose but we cannot see where we are going in time. Similarly we can’t see where we have been when walking from one place to another, but we can see where we have been in time.

Scientists have no difficulties with direction in time. In an equation with a time variable in it, one can trace the changes to other variables from the nominal zero point to see what would occur in the future, merely by incrementing the time variable. A scientist can predict the trajectory of a thrown item (a parabola) merely by substituting later times into the time variable in the equation.

y =ax² + bx + c

The scientist should compare these results to experiment and find, that this more or less works. Lets say though, that the scientist is an astrophysicist investigating an asteroid or other object on a parabolic trajectory around a larger object, like a moon or planet. (A parabolic trajectory is the trajectory which divides objects in hyperbolic trajectories which are not bound by the larger body’s gravity, from those in elliptical trajectories where the object is bound by the larger body’s gravity).

The astrophysicist would be able to track the trajectory of the body backwards in time, simply by substituting negative values for time into his equations. He would be able to see where it had been. However this process of substituting negative time values into the equations only works so far. At some point the body will feel the influence of other objects and the retrograde trajectory will deviate from the values predicted by the parabolic equation.

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Of course, if the trajectory is projected forwards far enough similar considerations arise. Eventually some other body will divert the body away from the parabolic trajectory. However in the region in which the parabola  applies, the behaviour is symmetrical with respect to time. From a film of the event one could not tell whether or not the film was being run forwards or backwards.

Of course, if a film is run backwards for any length of time, it becomes obvious that something is wrong. Things fall upwards, and broken crockery comes back together again. People walk backwards.

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On a closer look, people can intentionally walk backwards and it is possible that a spring or other mechanism could be used to shoot things upwards, but it is a lot harder to imagine a way of reversing the breakage of the crockery. It implies that some process involved in the breaking of crockery is not reversible at a macro level.

It is likely that the process in question is at the molecular level or slightly above. To rejoin two broken surfaces spontaneously would presumably require that the molecules be in the correct positions and that a little burst of energy (equivalent to the little burst of energy that comprises the sound that the crockery makes in breaking and any heat release) be supplied at an instant in time. The weak bonds between the parts of crockery would need to be created, and that is really difficult.

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There’s therefore a discrepancy between the scientist’s view of the world, through his equation which time-symmetrical, and the man in the street’s view of the world, which is asymmetrical with respect to time. In fiction this asymmetry is used to good effect, when the protagonist may “wind back time”, to write a wrong or divert history to an alternate course.

When we consider space we usually imagine a three dimensional space. Events happen at locations in this space and three coordinates are enough to locate an event in space. Every possible point in space has its set of unique coordinates. It is common to add an extra dimension for time, making the space four dimension and consequently difficult to imagine successfully.

All events in space and time have a location and time and are represented by a point in the four dimensional space. The path of a particle is a line within this space, and any point on the line represents the position of the particle at a particular time. Positions on the line are either before or after this point, so it constitutes a “now” point for the particle. There is no actual motion over the line, since in the 4-D space all points represent the past and the future of the particle. They are already there.

To move to an earlier time, all we need to do is move to an earlier spot on the line. We would need to either travel back along the line at a speed of so many seconds per seconds where the first “seconds” is seconds measured in the space and the second “seconds” is some other time scale or we could jump out of the space-time completely and return to the requisite point earlier in time. We’d need to do the latter in some other space-time that embeds the original space-time, adding a number of extra dimensions to the mix.

Both options require the addition of extra dimensions, which while possible complicates the situation unacceptably to my mind. The process of adding extra dimensions could be repeated and go on forever, so we end up with infinite dimensions. I believe that it is correct to employ Occam’s razor at this point and declare that it appears unlikely that we could either roll back time or jump to an earlier point in time because of the implication that we would needs infinite dimensions as a result.

## Discworld

There’s an apocryphal story of an eminent lecturer (some say Bertrand Russell) giving a lecture on astronomy, describing how the earth orbits the sun, the sun orbits the centre of the Home Galaxy, the Milky Way, when someone objects and states that the earth is a flat surface, balanced on the back or a turtle.

The lecturer questions what it is that the turtle is standing on, and the objector states that the turtle is standing on the back of another turtle. The lecturer asks what the second turtle is standing and gets the answer “It’s turtles all the way down“.

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It’s always struck me that the objector’s argument is paralleled by the lecturer’s own argument. The moon orbits the earth, the earth orbits the sun, the sun orbits the Home Galaxy, the Home Galaxy orbits the Local Cluster of galaxies. It’s orbits all the way down.

Of course the lecturer’s world view is a lot more sensible than the objector’s world view, wouldn’t you say? Well a confirmed sceptic would be dubious about both claims, but the man in the street assuming he wasn’t by chance a turtle believer would probably side with the lecturer.

It’s worth remembering that the current view of the universe as espoused by the lecturer is fairly recent in historical terms. Sir Isaac Newton and his near contemporaries (both in Britain and elsewhere) cemented the physical view of the world as the paramount paradigm. Again it’s worth noting that Sir Isaac and co did not completely ditch the mystical view of the world. He was very interested in alchemy for example, though this could be considered to be a rational belief at a time when the field of chemistry was still relatively immature.

Sir Terry Pratchett took the turtle theory and ran with it in the Discworld series of books. What would life be like on a world shaped like a disc, carried by four elephants, on the back of a gigantic turtle? This is the basic premise of Pratchett’s books, which I enjoy immensely.

Obviously, sort of, such a world cannot be ruled by the laws of physics, so it is ruled by the laws of magic, which seem parallel the physical laws in some ways. Pratchett’s Discworld clockwork is run by magic, not by physics. Indeed one of the characters muses on the magical laws and wonder whether or not there might be “another way”.

Threading the Discworld books and the Discworld universe are certain key characters, the first of whom is the failed wizard and professional coward Rincewind, from the first Discworld book “The Colour of Magic”. Rincewind’s quest for a quiet life is forever dashed by circumstances which often result in Rincewind escaping from some life-threatening situation or other by the skin of his teeth.

Rincewind’s case is watched over by Death, who describes himself as an “anthropomorphical manifestion” and who looks after a room full of “life-timers”, huge hour glasses containing the sands of a person’s existence. When the sand runs out, Death appears to the person and with a sweep of his scythe cuts the person’s lifeline. What happens then varies, but usually the person or soul travels over a dark plain.

Rincewind’s lifetimer apparently looks as though it was constructed by a glass blower with a bad case of the hiccoughs, and Death has ceased to wonder when Rincewind will die, but merely retains a “professional interest” in Rincewind’s exploits.

One thousand words cannot do justice to the inventiveness of Pratchett’s Diskworld. It is peopled by trolls, dwarves, werewolves, vampires, heroes (professionals of course), wizards, witches, talking dogs, a smell with its own personality, druids, priests, gods and godesses and many many other characters.

Over the series of books the geography of the Diskworld as are some of its physical (or maybe that should be “magical”) properties. The geography is centred socially in the twin city of Ankh-Morpork, and physically by the Hub Mountains (home of the Ice Giants and “Dunmanifestin”, the home of the rather down market major gods of Diskworld).

Sir Terry Pratchett’s Diskworld is, as can be seen from the above to be a complex one, interleaving and referencing many well-known myths and legends which Pratchett weaves into enthralling parodies of the originals.

For example, the heroes that Rincewind and others encounter are mostly bumptious self righteous individuals who seem to possess very little in the way of intellect. They win because they are heroes and heroes always win in the end, not because they are shrewd campaigners.

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An exception to this model of hero is Cohen the Barbarian and the Silver Horde. These ancient heroes are shrewd and survive because they have decades of experience in not dying. The overcome a bunch of martial arts experts by using there experience by not being there when the martial arts experts makes a move.

Pratchett references all sort of myths, legends and stories and often delves deep into the roots of the myth. He traces the roots of the “Father Christmas” myth in the book “Hogfather” back to one bloody version of the possible roots of the myth.

His coven of witches who appear in several books harken back to Shakespeare’s three witches in Macbeth and also to other witch myths, such as (supposed) pagan myth of the Maiden, the Mother, and the Crone. Shakespeare of course, like Pratchett is tapping into earlier myths.

The adoption of the alternate reality scenario allows Pratchett to tap into all these myths and legends and to mix and match them with similar myths and legends and put them up against present day society. There is for example the Last Continent of XXXX, obviously a reference to current day Australia, the social problems of immigration, typified by the Dwarves who are mild mannered at home, but who turn into drinking, carousing menaces singing about gold when they immigrate to Ankh-Morpork.

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Pratchett’s strength were to be able to draw on all these myths and legends and to build engaging stories around them. Even if you don’t know the legend, you can enjoy the characters and the story, and recognise the parallels with the real world.

You can enjoy the stories of the three witches turning the tables on card sharks who try to take advantage of three little old ladies, for example. Or the invention of surfing by the Burser of the Unseen University when the faculty find themselves offshore of the Last Continent (aka XXXX). Or sympathise with Death when he becomes disenchanted with his role as an “anthropomorphic manifestation” and takes a holiday.

You do all this while enjoying the marvellous stories. RIP Sir Terry Pratchett. You will be sorely missed.

## For the little gods’ sake…

(Spoiler alert: This post contains commentary on “Small gods” by Terry Pratchett and as such gives away vital plot details.)

I often use the phrase “For the little gods’ sake…” as an expression of frustration. I got the expression from the Diskworld novel “Small gods” by Terry Pratchett. The premise of the story is that everything has a god or goddess,  and there is even a Goddess of Things That Get Stuck in Drawers, Anoia. These deities are constantly jostling for prominence and for followers, because followers equate with influence and without influence a god will fade away into a sort of background of powerless whispering.

Anoia is lucky in this respect as much of her influence comes from the annoyance that people feel when they open a drawer and it gets stuck. She doesn’t have to rely on believers. In the stories minor deities who do not have enough followers are served by priests of more major deities on an agency basis.

Although Anoia’s cause if peripherally helped by the events in the book, the book’s main theme is another small god, who is in desperate straits as he has only one follower and is accidentally incarnated as a tortoise. He regains his deity by persuading an eagle to drop him on the head of the villain of the story, thereby killing both himself and the baddie.

Pratchett is obviously drawing on the story of Aeschylus’ death as a result of a tortoise being dropped on his head. The interesting thing is the theology that Pratchett weaves around the incident where everything has a god or goddess and there is a hierarchy of gods who continually jostle for position.

A huge pantheon seems, well, wasteful. One single Deity seems more logical, as gods are supposed to be all-powerful, all-seeing, etc. One way out of this dilemma is to see each member of the pantheon as being mere aspects or manifestations of the one Deity. Many religions seem to make this compromise.

A god is supposedly a non-physical being, and supernatural. A deity is supposed to be able to subvert the laws of nature and cause unexplainable things to happen. Most if not all deities are thought of by believers as anthropomorphic manifestations – in other words, like people.

However, a non-physical being presumably cannot have physical attributes, like people, so it seems to me to be wrong to believe that a deity is in any way like a person. One consequence of ascribing attributes to deities is to make them fallible as people are fallible. One only has to look at descriptions of the supposed behaviours of  the Greek, Roman or Norse mythologies to see the consequences of your deities having human characteristics.

Gods are powerful beings and in most cultures power equates to ambition and ambition leads to conflict. Goddesses, if the religion has them, are generally idealisation of the status of women in the society, the mothers, the sisters, the daughters, the wives and generally the peace makers and the artists.

The pantheon of many religions are an unruly bunch with cheating, back-stabbing, sex, killing and many other unsavoury pursuits, but these are stories made up by us humans about the deities. These behaviours are mirrors of our own best and worst characteristics, but on a heroic scale.

Obviously the stories come from the minds of the adherents to the religion, but where do they get the stories, how do these legends arise? They arise as a result of humans attributing human characteristics to their deities, and then wondering what they would do with these characteristics. The legend makers will see the goings on of the rich and famous and will see their deities behaving the same ways but writ larger than life. Others then pass these stories on as facts.

Deities are supernatural entities and have the ability to transcend the laws of nature. While many examples exist of unlikely, improbable and apparently impossible things happening, in the majority of cases it appears that there are physical explanations of these events. For a deity to perform a genuine miracle, then, the miracle should be without possible explanations.

The Roman Catholic faith has a church body which is concerned with verification of miracles called the “Congregation for the Causes of Saints.” They take miracles very seriously. Most modern miracles it seems are cures of illnesses, and documentary evidence of the state of health of the beneficiary of a miracle, both before and after the event are required.

I am uncomfortable with the concept of miracles as it is hard to see how a non-physical cause can cause a physical event. I’m not even sure that “a non-physical cause” makes sense. All causes are physical, aren’t they? An effect without a physical cause would not then make sense.

All physical effects seem to have a physical cause, even if the statement is softened to an assertion that the state of the Universe now is caused by the state of the Universe before and the tendencies or laws of nature.

The concept of a miracle changes this to something like “the state of the Universe now is caused by the state of the Universe before and the tendencies or laws of nature, or something else, outside of the framework of the physical Universe and the laws of nature”.

This pretty much means that anything can happen, but we don’t see this in practise. The Universe follows the laws of nature, be they classical or be they quantum physical.

If a deity cannot have physical attributes, because a deity is not a physical entity, then what attribute can a deity have? Certainly a deity would not have a gender as that is a property of physical biological entities, such a animals and plants. I’ve said above that I don’t think that there can logically be more than one deity, but singularity or plurality seem to be physical properties (but numbers may not be).

If we work back from the definition above, a deity is “something else, outside the framework if the physical Universe that allows things to happen that are not the result of the laws of nature operating on the Universe”. I think that’s a round about way of saying that we don’t know what a deity would be like if there is such a thing.