Time is one of the most fundamental aspects of physics. In most cultures, Time is described as the indefinite continued progress of existence and events in the past, present, and future regarded as a whole, but there is much more to it than that.
- "Space and Time" describes how time is known to work in the real world, while "Hyperspatial Physics" is about how time works in more detail in the main collaborative SporeWiki fiction universe, involving speculations of how gravity and quantum mechanics are connected alongside fictional dimensions.
Space and Time Edit
Starting with the basics, any description of reality needs to involve states, which are distinct things that exist. The concept of a space follows as a way of distinguishing any two different states that both exist. This general concept of a space can include dimensions, which are the numbers needed to describe each state (and not, as in the colloquial usage, different universes), and a metric, which defines distances between them.
The most useful space in the description of our universe is position space, more commonly known as spacetime. Spacetime is useful because it has the property of locality: things can only interact with each other when they are at the same point within position space, or via intermediates that cross the distance between them. Spacetime has four dimensions, three of which are known simply as space while the other is known as time. Time is as much a dimension as the spatial dimensions are - it is what distinguishes different states that exist at the same position in space, but do not interact directly and thus are still at different positions overall (events) - but is distinguished by the "arrow of time", which is the fact that these states can be consistently arranged into an order with each state depending on its predecessors but not on its successors.
This is similar to, but not to be confused with, the "flow of time", which is the experience perceived by conscious beings as a result of a) their brain states being ordered in the way dictated by the arrow, and b) the existence of a memory which stores information from previous brain states that can be compared to the active one.
The Arrow of Time Edit
The arrow of time is closely linked to the concept of entropy, which is a measure of how probable it would be for a collection of discrete units to randomly form a particular state. For example, there are many more arrangements of grains of sand that can be called a sand pile than a sandcastle, so sand piles are much more probable, and thus have a greater entropy, than sandcastles. The arrow of time is the fact that the total entropy of the universe, or that of any system of interacting states that does not rely on entropy increasing elsewhere, increases in one direction of time (the future) but not in the other (the past). Complex systems like sandcastles degrade into disordered ones like sand piles over time unless energy is brought in from elsewhere to do work to maintain them, but the release of energy from the interactions of particles at the power source will result in increased entropy there instead.
The arrow of time is also connected to the metric of spacetime, which also provides a link to locality. Although the metric is influenced by the presence of matter, one consistent feature is that worldlines - the paths of states through spacetime - cannot rotate freely through time; in fact, not only is it possible to reach an angle greater than 90 degrees between time and space while still pointing in a timelike direction, but an infinite angle still corresponds to a finite speed. This speed is constant relative to all states regardless of their own space-time angle and thus serves as an upper limit known as the "speed of light" (so called because massless waves, such as light waves in a vacuum, travel at that speed).
Naturally, this is all very counterintuitive for organisms that evolved in a low-velocity world where spacetime can be treated as a perfectly Euclidean three-dimensional space with a constant flow of time. Even less intuitive is one of its consequences, relativity of simultaneity, which is the phenomenon by which two observers travelling at different speeds will not agree on which events are in the past and which are in the future. As difficult to visualise as this may be, it is entirely analogous to how two observers facing in different directions will not agree about which positions are to the left and which are to the right.
Combining this with conservation laws (where interactions that do not change when some variable that they depend on is altered result in a quantity that does not change in time; for example, interactions that are the same for all positions in spacetime result in energy and momentum as conserved quantities), we obtain that important property of locality: a quantity could be conserved if it decreased in one location while increasing in a different location at the same time, but "the same time" is not a universally-valid concept for different locations. Conserved quantities, which are how all information must be transmitted for it to have a reliable output, can only travel continuously, point by point.
A specific case of relativity of simultaneity is that for two events, seperated from each other by a greater distance than which light can travel in the time between them, one will occur before the other in some reference frames, and after it in others. This means that a faster-than-light (FTL) jump between two distant points in space, followed by a change in sublight velocity and then another jump to the original location, will - if the combination of FTL speed, change in velocity and spatial distance is great enough - arrive before it left. This, of course, requires a means of getting around the geometric problem previously mentioned to be important.
Time in Other Metrics Edit
The description so far has been that of "flat" spacetime, where space is simple and Euclidean while time is distinct but the overall metric is still not complicated. However, the flow of energy and momentum is capable of altering the metric in the interaction known as gravitation.
The most common low-energy gravitational effect occurs when, simplistically speaking, the direction of the future is altered so that, as well as in the time direction, it also points slightly towards the most significant nearby centre of mass. Then, just as objects inevitably move into the future, they also inevitably move in the direction of said mass unless a constant force is applied to counteract the gravitational acceleration. When this "gravitational field" changes in strength over a short enough distance, the difference in accelerations between two pieces of a material - one accelerating more slowly in a region of weaker field, the other more quickly in a region of stronger field - will overcome the forces holding them together and cause the material to break apart.
When there is enough mass within a small enough volume, the outcome is that there is a region of space in which the future ends up being directed more into space than into time, and either a speed greater than the speed of light or the ability to travel backwards in time (which, by relativity of simultaneity, are somewhat equivalent) would be required to escape this region, with any acceleration causing speed to increase towards the centre. The region itself is known as a black hole while its boundary is the event horizon.
Another elementary effect is the gravitational wave. Although time is not generally so warped inside such a wave, a "thunderbolt" is an example of such a thing, essentially taking the form of a propagating massless (but just as destructive) black hole. But within the limits of positive-on-average energy-momentum currents, macroscopic gravitational phenomena such as these are limited.
Hyperspatial Physics Edit
The description of spacetime as four-dimensional is usually an apt description, but is not truly accurate. All information about all states within the universe can be expressed in a three-dimensional surface - this is the holographic principle - and for the 4D universe that is metaphorically projected from it like a hologram, this surface acts as an outside boundary.
Furthermore, the influence of Essence in the early universe was used to create a five-dimensional realm within which this 3D surface is contained. This can be visualised by imagining the universe and its history to be represented by a 2D surface within a more familiar 4D room. In contrast to its cosmic overall size, the surface is folded on a microscopic scale (close to the planck length, ~10-35 metres), and it is possible for objects to escape the surface and travel in the higher-dimensional space between the folds known as hyperspace. This requires the use of energy densities close to the planck energy density (~10113 joules per cubic metre), but it allows the objects to cover a shorter distance between any two points than would be possible if they were forced to travel along the folds, allowing for what is functionally faster-than-light travel.
Alternatively, matter held within hyperspace but fixed to multiple folds acts as negative mass from the perspective of observers on the folds, which has many technological applications: for example, it is a vital part of advanced artificial gravity systems, being used to limit "gravitational leakage" and reduce inertia. Most significantly, it can manipulate the spacetime metric in ways not possible for positive mass, to produce geometries that allow for other forms of FTL travel to occur such as warp drives and wormholes.
As previously mentioned, FTL travel should lead to easy time travel, and even without that negative mass can also be used to make pure time machines out of the metric. What makes time travel more difficult is the presence of hypermatter, a hyperspatial superfluid, which forms currents directing starships along routes that limit their pastwards time travel and collects around time machines in a way that disrupts their metric engineering. These currents and congregations can be disrupted by precise perturbations, but this requires highly advanced hyperspatial technology and is computationally and energetically intensive even for civilisations capable of such a task. Still, travelling through time to the past is certainly possible.
Time Travel and Paradoxes Edit
As spacetime is simply an ordering of states, it follows that states are the same at one point in space and time as they are at that same point in space and time. This means that the popular concept of going back in time and changing history is not literally a valid concept, although the nature of quantum mechanics means that the same effect for most practical purposes can still be achieved.
The simple classical case, where an individual travelling backwards in time does not change the outcome of events, is known as Novikov self-consistency, and can lead to predestination paradoxes. The general concept of a predestination paradox is that information related to the circumstances of time travel does not exist before the causal loop, where the loop starts with the arrival of a time traveller in the past and ends with their departure to the past from the future. For example, a time traveller causes an event in the past that they travelled back in time to visit or prevent, or a work of art is copied in the past from a copy that was sent from the future and therefore exists with no creator.
With quantum mechanics, the possible situations become more varied. Ultimately, elementary "particles" exist as wavelike structures (wavefunctions) propagating throughout the entire universe, and because opposing oscillations of these waves cancel each other out, classical worldlines are paths through space and time where these oscillations are minimised. Many events have multiple possible worldlines leading from them, and every collection of interacting worldlines that leads to a certain end state is called a timeline. Since the number of end states increases with every event that leads to multiple worldlines, we say that timelines "branch" as time passes (an increase of entropy in the universe's own collective wavefunction).
It is possible for a time traveller to connect their worldline to a timeline different from the one that they started from, which is known as many-worlds time travel, and allows them to effectively change history, which can lead to prevention paradoxes. A time travel event in a prevention paradox, rather than creating the circumstances that led to it arising, destroys them. A classic example is the "grandfather paradox" whereby a time traveller takes action to prevent themselves from being born, such as by killing their own grandfather before their parents were conceived.
They can also be more subtle. Similar in appearance to a predestination paradox is where matter, rather than information, appears in the past, then at a later date is sent backwards in time to emerge at the same event at which it first appeared. However, because any material will degrade over time, and living organisms will age and acquire new memories, this is an unstable situation, since the matter at the end of each loop will be different from the matter at the start. Repairs can be conducted, but unless the entire material is replaced during the loop to match the original object (in which case we have a similar situation to the artwork predestination paradox) then it will enter a different timeline in each instance of it going backwards in time. However, if the entire material is replaced over a number of timelines, then these timelines will end up being connected in a loop with the "first" timeline in which the object appears leading on from the "last" timeline in which the replacement in completed.
Many-worlds time travel clearly contradicts classical Novikov self-consistency: in the grandfather paradox example, if the time traveller were never born then they couldn't have travelled back in time to prevent their birth, and without their birth being prevented they must have been born. However, the universal wavefunction overall is Novikov self-consistent. Instead, the time traveller now experiences a different timeline in which they appeared from nothing; from their perpective this is practically a different universe, hence the "many-worlds" name.
The real problem is that departures from a single stable timeline correspond to departures from classical worldlines and thus reqire motion along paths through rapidly-oscillating wavefunctions. This means that the greater the change, the more difficult it is to achieve; less oscillatory semi-classical paths leading back to the original timeline will manifest as highly improbable situations seemingly conspiring to maintain the timeline, requiring additional effort to counteract.
Essence and Chronoscopic Edit
While Essence was involved in making the universe five-dimensional, its power extends far beyond that. Of the four major classes of Essence, of two of them are directly related to the cosmology previously described: Elemental is Essence that is contained within the 4D universe along with hyperspace, while Chronoscopic is fully 5D and is thus able to manipulate worldlines and timelines anywhere in the universe. To use the lower-dimensional analogy of a 2D surface representing the universe, Chronoscopic is able to move above and around this surface and reach any point on it, which means any event in spacetime at any part of the universal wavefunction. As Essence is non-quantum in nature, it lacks its own wavefunctions and hence timelines, which for Chronoscopic, this combined with its 5D nature means that it is ultimately beyond any normal conception of time and immune to any changes in history caused by many-worlds time travel or time editing.
Conversely, Chronoscopic's power over 4D spacetime is practically absolute, as it can alter the universal wavefunction with ease, performing acts ranging from causing improbable events to happen in specific timelines to erasing entire sets of worldlines from history (removing objects and their consequences from time), as well as general Essence powers such as interacting with matter in otherwise-impossible ways and violating conservation laws. Chronoscopic's ability to move freely in five dimensions, beyond even the reach of hyperspace, also grants it a greatly enhanced scope of editing the metric of 4D spacetime.
Abuse of this near-omnipotence by inhabitants of the regular universe is restricted by two means. Firstly, unlike Elemental Essence, Chronoscopic is not omnipresent in useable form throughout the whole of spacetime, so for an individual to utilise it they must first find a manifestation in the form of Chronoscopic Matter, which as with all forms of "solidified Essence" is matter that has been connected to Essence in such a way that said Essence will be responsive to mental commands directed through the matter. Only the Chronoscopic Matter known as holomatter is useful in this way; the metallic Gyronidium will not respond to commands unless they are passed through holomatter first.
The second mechanism that prevents abuse is that Chronoscopic is itself conscious (as is all Essence) and is dedicated to preserving the temporal order. This consciousness is centred around the godform Vyro'Nazdea (Volzara) and the structured region of Chronoscopic Sequencium, and is divided into two groups of spiritual beings: the Vyro'Narza (Taldar) and Vyro'Ralza (Traffphyds). The former are associated with Light Chronoscopic, generally just referred to as Chronoscopic, with gold and green holomatter and gold Gyronidium, while the latter are associated with Dark Chronoscopic with purple, red and black holomatter and Gyronidium. The differences between the two are mainly in their application; Dark Chronoscopic is more adept at destructive and chaotic interference with timelines.
Chronoscopic is also capable of enhancing the Elemental souls of individuals who have assimilated holomatter into their bodies, granting increased knowledge and comprehension of spacetime and different timelines. Both Chronoscopic-enhanced souls and pure Chronoscopic spirits may make unconscious use of their power over the universal wavefunction to perform instantaneous quantum computing, by changing worldlines that originate from a single event so that they continue to interact with each other rather than branching into different timelines. This ability is, nonetheless, also restricted by Volzara's desire to avoid excessive interference with the course of time.
Time Anomalies Edit
As the mechanics of Essence are not the local dynamics of wavefunctions but connected to emergent phenomena and mental perceptions, Chronoscopic misuse can easily result in Time Anomalies, complex disturbances to the arrow of time associated with discontinuities in the timelines of the universal wavefunction.
- Time locks: All wavefunctions in a region of spacetime are prevented from changing, or in other words are "frozen in time". Often the entire region appears a perfectly black void, but sometimes light can still pass through and reflect off any objects inside.
- Time loops: A section of timeline is repeated, with a sudden return to the initial state after a certain period of time. This might occur only once, in which case it also resembles a time skip (see below), but usually repeats itself multiple times.
- Time reversals: A section of timeline is reversed, with spontaneous entropy increase such as broken items unbreaking or objects falling upwards against gravity.
- Time skips: Sections of a timeline are rearranged; for example, a period in which somebody is alive is transplanted (often after being copied) so that it occurs after their death, before the timeline instantly returns to a state in which they are dead.
As memories are also altered in the process, individuals without Chronoscopic-enhanced souls do not notice that the flow of time is unusual when they are within a Time Anomaly, and if they enter one from outside, they are either incorporated into the Anomaly or (especially with time reversals) destroyed at the boundary.
A Time Anomaly not associated with timeline discontinuities is the time slip, in which different sections of timeline - either different periods of the same timeline, or different timelines entirely - temporarily intersect before diverging again. Usually this divergence is so clean that every living being is returned to its original time and timeline, leaving only traces and memories of its presence behind.
- The original version of this page was contributed towards by Technobliterator, Wormulon, Ghelae, TimeMaster, Cyrannian and The Randomness.
- The current version was written by Ghelae with help from Technobliterator and Wormulon.