Space Travel Part Three : Transdimensional Travel

Transdimensional Travel
This class of technologies beat the Light Barrier by circumnavigating normal Space-Time.

Wormhole Science

Though technically never leaving the four dimensions of immediate Space-Time Wormhole travel might be classed as the most basic form of Transdimensional travel in that detours the normal dimensional trajectory.

Schwarzschild Wormhole

The early idea behind this idea was that a Schwarzschild Wormhole (an idealised Black Hole, that is described by the maths of the Schwarzschild metric) could become a Einstein-Rosen Bridge if it generated its opposite reflection, an emergent White Hole, that was connected to it by a funnel of Space-Time. The White Hole was assumed to be somewhere else in the Space-Time Continuum.
Travel via such a bridge would cut the corner off huge distances as it effectively connected distant loci on a plane folded over to connect via a short tunnel, which could be passed through at some finite speed. This was mathematically determined to be possible under conditions of extreme Space curvature and the presence of a natural Black Hole. But this was initially refuted in two stages, primarily it was realised that no traveller could get passed the Singularity alive, and while a rare form of charged, rotating Black Hole was said to create an internal path bypassing the naked Singularity, it was later found that charging a Black Hole was impossible. Some versions of the equations suggested that despite these problems travel could still be possible, but this too was later refuted by equations showing that such Wormholes were dynamic and unstable, and constantly forming, breaking up and reforming. Most damningly the Wormhole collapses before even an object moving at the speed of light could pass through it.

Morris-Thorne Wormhole

This is a variant based on the idea that a bubble of Negative Mass could keep the funnel open long enough for a crossing by forcing the neck apart. This worked on paper whether it does in reality is much contested. Even if it did it faces the problem that Schwarzschild Wormholes have been since found not to occur in Nature. This means Wormholes have to be created, the hard way to do this is to bulldoze matter into a compact space in order to create an artificial Black Hole, but such a project would be a mammoth undertaking and difficult to perform. A more reliable way is to create a micro Black Hole in a particle accelerator, put it in place and then inflate it with Negative Mass or Energy. How stable this would be is controversial.

Gauss–Bonnet Wormhole

This is modelled on a higher dimensional Space-Time than the 4D matrix of the standard models, and results suggest that Black Holes and Wormholes may be stable after all, or at least stable enough to allow transit. It is purely a Mathematical theory however and maybe false.

The Dynamics of Wormholes
At present there seems to be know way to predict where a Wormhole will emerge, and there is also the added complication that it may facilitate time travel as well as space travel. Furthermore in bringing in extra dimensions from M-Theory we find that the Wormhole may lead to an entirely different universe or into its own micro-universe. The time travel issue appears to be due to a differential spin on the entrance and exit of the tunnel, and so keeping them in sync may stabilize the Wormhole. In addition the hyperdimensional and local Wormholes may be differentiable in any practical technology.

That said it still does not seem possible to target the exit of the tunnel anywhere. Theoretical models describe towing the exit to the terminus point before using it. This would not be an issue for a time tunnel, but it would been any space tunnel journey would have to be performed in real space first, which limits the possible range of the Wormhole. It also implies that the energy input for locating the exit is going to be equivalent to the energy used to actually get there conventionally. So even if some remote space warping technology was developed, dispelling the need for physical travel above, the energy input would still be an issue and would severely limit the range of these Wormholes (one guesstimate suggests the entire energy output of a giant star may be needed to even jump a few hundred Light Years). But optimistic guestimates suggest that a very massively energised Wormhole might form a bridge across a significant section of our galaxy, giving a range of say a few thousand light years (or up to ten percent of the Galaxy’s diameter), though any more will be beyond the reasonable expectation for the energy resources of even the late 23rd century. This may thus extend our range as far as the Dolidze 25 Star Cluster, 17,000 LY away, but still leaves much of the Galaxy untouched. Over time perhaps the whole of our Galaxy might become honeycombed with such Wormholes (assuming that this was not structurally destabilizing and dangerous), but as the Intergalactic distance is at least over 2 million L Y with nothing in between, and even the ‘mini galaxy’ of the orbiting Magellanic Cloud is 160,000 LY away, this will probably be permanently outside the range of any Wormhole technology.

One outstanding problem is that unless the exit point of a Wormhole pumped thousands of Light Years across space can be predicted we might never know where it is or what its state is and so it may be anywhere, at any time in any universe, or even nowhere at all.

Hyperspace and Slipstream Travel

This is a purely science fiction concept with little correlation with anything in modern physics, though was borne of earlier scientific models. The basic idea being if the universe were shaped like a doughnut then it might be possible to pass through some limbo in the central hole and take a short cut to any destination. Wormhole travel without the Wormhole. How this space could be entered was unknown and science fiction writers suggested superluminal breakthroughs or field dislocations that made little scientific sense. But the whole idea is incompatible with contemporary Physics as there are currently only two theories that relate to this possibility and both reject the idea of such travel.

Four Dimensional Quantum Tunnelling.

Here it is held that there are only four dimensions to Space-Time so the hole in the middle does not actually exist it is just a mathematical illusion, and the space curvature is a kind of mathematical metaphor for gravity, which has no concrete reality other than as a useful model. Therefore in this view Hyperspace does not even exist. There is one loophole out of this in the form of Quantum Tunnelling, a known subatomic process by which particles can cross barriers or gaps which would normally be uncrossable, purely as a result of quantum uncertainty. This could be seen as passing though some invisible realm and if it was scalable to the macroscopic domain could be regarded as a jump through some technically non existent realm, equivalent to the ‘hole in the doughnut’, and therefore similar to instantaneous Hyperspace jumps, though would be experienced more as a series of short teleportations in a longer trajectory. However this may not be very helpful as current estimates suggest such a trajectory would only be equivalent to travelling at 1.7 times light speed.

Higher Dimensionality and M-Space.
The mathematical possibility of there being more than four dimensions to the cosmos, plus the counter-intuitiveness of spacial curvature being simply a metaphor (it seems that if something like this is described mathematically, with predictive results, then there must be some kind of actual curve, and so a dimension it curves into), has long driven a search for a fifth dimension or even higher dimensionality. Dimension in this sense is not meant in the vulgar science fiction sense, of another universe, but literally as another direction or new axis of extension. Just as we can move forward and back, left and right, up and down, or through time, we may be able to move in a new direction x that is normally off limits to us. However searches for such higher dimensionality have
proved fruitless, and until recently the only theoretically sound model for them were the curled up micro-dimensions of String Theory. More recently though String Theory gave birth to M-Theory, which models a Multiverse of normal Space-Time universes separated by higher dimensional M-Space. This is effectively what has been called Hyperspace, but unfortunately the only force that can pass through it is Gravity, matter is confined to normal Space-Time, thus Hyperspace travel is impossible here too. The possibility of M-Space teleportation remains but that will be dealt with in another section.

Today the impossibility of Hyperspace travel has even fed though to science fiction writers, and so vaguer concepts such as Slipstream travel have been mooted. These are never described in any detail, but are effectively just Hyperspace travel under another vaguer name. In the 23rd century today’s Science Fiction may well seem like a Baron Münchhausen story.

Hyper-dimensional Bubble Transit

We are currently left with only one remaining form of direct Hyper-dimensional travel. If a local area of Space-Time could be gravitationally expanded into a blister bubble, attached only by a thin neck to the rest of the universe, it might become detached as a micro-universe. Such a bubble of Space-Time could float through M-Space and completely circumnavigate normal Space-Time. The only problem might be reattaching to the Universe, but if we imagine the two as large and small soap bubbles then the two may recombine on contact, and the gravity between them would be enough to pull them back together again. If Quantum Space-Time really is a seething mass of chaotic foam rather than a continuous elastic plane then this scenario is at least plausible. Trajectories through both space and time might be similar to a hyper-dimensional catapult, where sufficient gravitational force and direction is imparted to an object to detach it on a certain parabolic path, completed by the pull of gravity from the universe. The catapult method also solves the problem of how the bubble could be maneuvered in M-Space, other than by some form of gravity beam, which alone could interact in M-Space. Though such gravity beams if possible would allow a much more sophisticated vehicle (and should not be difficult for a technology that could punch out the bubble in the first place through gravitational manipulation). An issue here might be whether the energy required to do this is obtainable. An alternative method might be through the attraction of a natural hyper-dimensional Wormhole in M-Space, as such a form intersecting on our Space-Time would appear as such a bubble and could shear off with only a little energetic input. The attraction of such a Wormhole would itself be haphazard of course and hardly practical, unless one was permanently captured by a device and associated with it. Such a craft would be curiously like a Whovian Tardis, in that it would interact with our universe through a tiny neck, probably engineered as a doorway or portal, that lead into a much larger space than that occupied by the portal (the craft within the bubble or transverse wormhole). The portal itself would be a three dimensional object that would have to be sealed from the environment. As the neck of the bubble detached this object would appear to shrink rapidly till it disappeared, and vice versa when it reattached. It could of course move through Space-Time the same as any other object, and could even have its own secondary propulsion system. A catapult system that was over forceful could boost the device deep into M-Space and without a primary propulsion system would float there till captured by another universe. This would be analogous to a vehicle achieving escape velocity in orbit and floating between planets (though the planets may be very alien indeed). Other than this we are in the realm of pure speculation.

Hyperdimensional Dilemmas
A final knotty problem here is whether this kind of transport would involve Time Travel or not. The classic picture of Relativistic Space-Time would suggest it would, but this doesn’t take higher dimensionality into account. Is the universe within the Multiverse constituted by Space-Time or just Space? In simple terms does leaving the universe also include leaving Time and re-entering at a different time, just as with Space, or is it still within Time and just leaving Space. In other words is M-Space itself within Time or does it transcend the Time of our Space-Time? If the latter there must be a second dimension of Time for it, or no change or motion could occur in it. Yet M-Theory only has one Time dimension, which suggests only Space travel would be possible, much like a Hyperspace jump. But part of the problem here may be the difficulty in comprehending the complex dimensionality. We can leave the 2D surface we stand on by jumping into the third dimension, but we still move through three dimensions. However in this case the third dimension has completely different properties than normal Space and may not have the limits of our universe, allowing a short transit between distant locations. But on the other hand this gravitational dimension still obeys gravitational laws presumably, and so the speed of light might be constant here too? The non-local phenomena of Quantum Physics indicates there may be an unlimited mediator that does allow instantaneous transaction, perhaps a higher dimension? This may be M-Space or some other dimension. We do not have to limit our speculation to M-Space of course, and have done so so far purely because it is an established hypothetical reality, but new theories may find even more extra dimensions with their own unique properties. So there may be an X-Space and a Y-Space too. It may turn out that M-Space has similar limits to normal Space and so does not allow useful shortcuts, while X-Space allows instantaneous short cuts between locations in our Universe. Quantum Entanglement might well work via such a dimension, perhaps Q-Space, if not M-Space itself, if it is in fact a extra-dimensional phenomenon. Moreover if Y-Space were a second Time dimension perhaps Time travel would also be possible by M-Space or some other higher dimension. The same principles of Bubble Transit would apply in all these dimensions and only the axis of expansion would vary. But all this is purely imaginative speculation, M-Theory is still a mysterious and vaguely understood theory at the current limits of a Physics whose future frontiers are still unknown. Moreover as we have learnt from Quantum Physics such foundational realities may not be completely intelligible and so such speculation pointless!


Space Travel Part Two : Gravitational Technology

Gravitational Drives

A range of methods for propulsion through gravitational manipulation exist, but how this can be achieved is uncertain.

Negative Mass / Energy
Negative Mass or Energy is another polarity in Nature similar to the Matter / Antimatter duality, but along a different polar axis (both Matter and Antimatter respond in the same way to Gravitational Fields. The strange property of Negative Mass is that it generates a repulsive Gravitational Field as opposed to an attractive one, however the Negative Mass itself is just as attracted to Gravity as is Positive Mass. This creates a strange paradox of the Negative Mass being attracted to a the Field of a Positive Mass while its Negative Gravitational Field pushes it away. Thus both Masses will accelerate in the same direction the Negative Mass for ever chasing the retreating Positive Mass while the distance between them remains constant. If they ever met both Gravitational Fields would be neutralized and the resultant Mass would have no Gravity (which is prohibited). Whether Matter with Negative Mass exists or not is controversial, it is theorized that large amounts of it may exist in isolated regions of space, and so could be farmed if we can get there. But more practically it is a predicted by-product of the Zero Point Casimir Effect, the juxtaposition of two plates at a Quantum distance apart, believed to release free energy (in simple terms meaning the Zero Point Quantum Potentia, the non-dual vacuum from which everything emerges, is squeezed into producing energy from nothing, as 0 = -1 plus +1, a state which can randomly revert into a -1 and +1 state on the various axes, for Quantum time scales, and where a slight inequality can produce a surfeit of +1 or -1 after their mutual cancellation back to zero. The Casimir squeezing affect creating inequalities in a generally negative axis). But this only produces microscopic amounts of energy and particles, including those with Negative Mass and it seems difficult to build up large supplies over time (though not impossible). A more practical way is to fire a laser into a silvered crystal, creating an optical resonator, this squeezes the light at a quantum level and creates pulses of positive and negative energy. Another way of looking at Negative Mass is as a hill rather than a valley in Space-Time, so that instead of everything falling into it, everything rolls away, thus a traveling wave is generated. If a Gravity Field could be generated as easily as a Magnetic Field then so could a Negative Gravity Field. At present we have no idea how this could be done, so all theories and examples deal with Negative Energy or Mass and ways of moving this around. One problem is that the cusp of the peak and trough of the wave might cancel gravity completely and even open a hole in Space-Time, a Singularity where the laws of nature break down and anything can happen.

Diametric Drive

A Diametric Drive is a theoretical propulsion system in which a Negative Mass is somehow produced behind a Positive Mass (the vehicle) thus accelerating it to the speed of light. The risk is of a formation of a Singularity forming in the ship and negating the laws of nature there.

Bias Drive

If the Gravitational Constant could be changed in a given area, perhaps by affecting the interaction of subtle forces believed to create Gravity, the polarity of the Field behind the vehicle might be inverted to a negative polarity, creating a Diametric Drive more subtly..

Disjunction Drive
The bizarrest Gravitational manipulation would detach the source of the field from that which was affected by it. Thus the object at the bottom of the Gravity Well might be shifted back to the slope and in effect be constantly attracted to its own Gravity Field shifted forward. Current Physics now suggests this is impossible, however some fringe theories suggest it might not be.

All these technologies accelerate vehicles to near light speed, however a special variant may allow superluminal travel.

Warp Drive (Alcubierre Drive)
This ingenious solution to faster than light speed proposes expanding Space-Time in front of a vehicle and contracting it behind it, possibly by the deployment of Negative Mass, or manipulation of the local Gravitational Field, thus creating a bubble of space within a travelling wave along which the vehicle is carried. The vehicle can also move within this bubble as well, like someone walking on a moving escalator, thus the speed of the moving bubble is added to the speed of the vehicle to give the total speed of the vehicle. While the wave can only reach the speed of light the vehicle can achieve this as well, creating a combined speed greater than C, but with neither bubble or vehicle technically exceeding C. At least twice the speed of light can be achieved in this way, and it is speculated that warp bubbles could be built within warp bubbles, up to a certain limit, creating an extended ‘Warp Factor’ increment akin to Star Trek’s Warp Drive. But here we enter the zone of pure speculation. A simple build up of bubbles, one inside the other, would give multipliers of the order of ten, but as the scriptwriters of Star Trek found this isn’t much better, a neighbouring star like Sirius is still months away, and lifespan star trips still only extend as far 250 LY or so, getting us as far as Canopus, but no where near Galactic travel, covering about 0.25% of our Galaxy (the Galaxy having a diameter of 100,000 LY) or about half a billion of its 250 billion stars. Probably enough for basic Sci Fi but almost certainly sparsely inhabited by even the most wildly optimistic Drake equation. Star Trek thus gives each Warp Factor an exponential expansion, originally with a max of 100 c, but later extended to thousands of c (still making a cross Galactic trip only possible in a thousand years or several decades respectively, but opening up a lot more of the Galaxy, between 2.5% and 50%). It’s daunting to think that even at 2000 times the speed of light half our galaxy would still be unreachable (especially as pessimistic Drake equation results give only one or two sentient species per galaxy). But how much of the Star Trek fantasy is realistic? The multiplier would depend on the number warp bubbles possible (the number of escalators moving on top of other escalators). Common sense would limit this to a visualisable few dozen, however if the warps were possible at a quantum scale this could be increased trillions of times, perhaps via an extreme concentration of super-massive particles. The limiting factor would be the amount of energy required, and given that an antimatter engine, the currently known limit of energy production, is predicted to only accelerate a vehicle to 90% of the speed of light the high end of the scale would seem to be very unlikely. So even the early Star Trek’s 100 c limit is quite optimistic. So a 23rd century Warp Drive technology would probably still have the 2.5% limitation.

These technologies are targeted at space travel, but a Negative Mass generated above an object on a planet would still lift it up and accelerate it vertically until negated (and likewise a Negative Mass behind it would drive it forward in any direction at up to the speed of light (though such speeds are impractical on Earth). Similarly a Disjunction Drive could move an object on Earth in any direction including vertically. So Earth bound transportation and flight could also benefit from this technology. However strictly speaking this is not Anti-Gravity in the classic ‘UFOlogical sense’, where objects become ultralight or massless and float around or defy inertia, as the Diametric Drive and Disjunction Drive leave the vehicle with its own mass intact and simply apply forces of attraction and repulsion. Any attempt to cancel a Gravity Field, by superimposing a Negative Gravity Field for instance, runs the risk of creating a Singularity, because the two fields would be pulling apart from each other and undermining all the laws of Physics. Moreover there is currently not the slightest idea in contemporary Physics how this would be even possible (of course this does not make it impossible!).

Space Travel Part One : The Rocket Men

Conventional Propulsion Systems

We begin this exploration with a brief look at Conventional Propulsion Systems. This is a rough guide intended for contextualization, I use it to give a framework for science fiction writing, it may also be useful for role playing games. For a more technical exploration a fuller treatment can be found by goggling the keywords used below.

All these rely on thrust from the rear of a vehicle pushing it forward at an accelerating rate:

Liquid Fuel Rockets (Liquid Oxygen, Hydrogen or Hydrazine based).

This is standard contemporary technology, based on very short intense bursts of fuel that can accelerate a large rocket to speeds of around 25,000 mph (or 40,000 km/h) very rapidly. That’s equivalent to Mach 4 ,or the fastest possible airspeed of any experimental aircraft today, such as the hypersonic Scram-jet. Rockets work both in space and the Earth’s atmosphere. The limitation is fuel mass, as even the largest modern rocket can only hold enough fuel to accelerate it to the Moon and back, and not much more may be technically possible. An orbitally or lunar launched rocket, even more massive than the Saturn V that went to the Moon, freed from the need to escape Earth’s gravity, might be able to make a trip to Mars or Venus and back, a possibility that is still a research project for Space Agencies. A Lunar trip thus takes around 12 hours and a trip to Venus or Mars would take about a month and two months respectively, and the same time to return, after awaiting planetary alignment. In theory Interplanetary travel would be possible as hops between planetary bases, though trips between the outer planets would take over two years.

Ion Thrusters (Xenon, Argon, Hydrogen based).
The electrical acceleration of plasma produces a small but continual thrust that can last for several years (current technology lasts for up to 5 years, but in theory might last for decades with resilient components, efficient thrusters and maximum fuel load). The technology works by ionizing stored fuel via electron bombardment and accelerating it via an electric field as thrust. The actual thrust produced is tiny but its consistency produces a very slow acceleration with only a tenth of the fuel, allowing much further missions at speeds of up to 10,000 mph. Current thrusters use Xenon fuel, a rare and expensive element, used in small amounts in relatively light satellites and probes, but experimental thrusters use the more abundant and cheaper Argon fuel. Argon can be harvested from most planets thus allowing refueling. While theoretical models could use Hydrogen fuel scooped up from interstellar space, allowing an unlimited range in terms of fuel. A limit is in the electrical power requirements which are light enough in the solar system to draw on solar power but in interstellar space would require a small nuclear reactor. Acceleration to 10,000 mph would require a month with typical thrust levels, higher speeds are theoretically possible with longer thrust duration, current projections indicate maximum speeds of 100,000 mph with a years acceleration. An important limiting factor is the mass of the vehicle given the light thrust which may limit the size of craft to shuttle size. At that speed a vehicle would take 7000 years to reach the nearest star four light years away, and even with gravitational assisted trajectories the mission would be several thousand years long. Thus only Interplanetary travel is realistic with Ion Thrusters. A trip to Mars would take about 5 months, a trip to Jupiter about a year and a half, and a trip to Pluto around 5 to 6 years (as opposed to at least 15 years in a Fuel Rocket). Thus Fuel Rockets are still swifter for Mars and Venus, if the fuel problem is soluble, but beyond that they lose out to the Ion Thrusters. These Thrusters do not work in an atmosphere.

Nuclear Propulsion
There are several kinds of what can be called Nuclear Propulsion

Nuclear Thermal Rocket
This heats liquid hydrogen fuel as it passes over a nuclear reactor, producing a super heated thrust that is slightly less than a liquid fuel rocket but which requires much less fuel and is much lighter. The net result is a Rocket traveling at 30,000 mph with a much greater range. This would be ideal for a Mars mission or trips to inner planets, but is still trumped by Ion Thrusters for the outer planets of our Solar System. It poses a risk of a breach of the reactor / propellant barrier thus releasing radioactive exhaust, so would be a space born technology entirely. There is also a risk of the heat melting the engine under extreme performance.

Nuclear Pulse Propulsion (‘Orion Drive’)
The most basic form of theoretical interstellar travel currently possible, essentially by exploding small nuclear bombs to the rear of the craft driving the shielded vehicle forward. Needs to be used at some distance from Earth, ideally in deep space. Estimated velocity 10% C (light speed). Reaches Pluto in about a month and Alpha Centauri in about 40 years (thus requires some form of cryogenics) and Sirius in about 90 years. Radiation affects may make this safer for unmanned craft only without sufficient shielding. Called Orion Drive after the first hypothetical craft.

Fusion Drive (‘Daedalus Drive’)
A contained nuclear fusion reaction in a drive tube has been estimated as producing speeds of up to 12% C and to be much safer than NPP, but interstellar journey duration would be similar. The fusion reaction may not produce a great deal of surplus power for ships systems however, making manned missions less likely, and an additional nuclear reactor reactor for ships power would add mass and reduce top speed to 5% of light speed, giving a 80 year Alpha Centauri trip, it would only add a few days on the Pluto trip however. Fusion may be developed by the mid 21st century. Given accelerated technological development an Anti-Matter Drive could be perfected before a Fusion Rocket arrived at the nearest star and thus arrive before it, arguably making such trips unlikely to be practical.

Antimatter catalyzed nuclear pulse propulsion
This tweak to the Fusion Rocket would lower the amount of nuclear fuel required by catalyzing fusion with antimatter. Thus vehicle mass would decrease and a fission reactor could be added to a 0.1c vehicle.

The Acceleration Rate for high performance Fusion Rockets

In 5 mins reaches 6,700 mph
In 45 mins reaches 67,000 mph
In 8 hours reaches 670,000 mph
In 3 ½ days reaches 0.01 c (6.7 million mph)
In 36 days reaches max 0.1 c (67 million mph)

Giving a trip to Mars in 3 days, a trip to Jupiter in about a week, a trip to Saturn in a fortnight and a trip out to Pluto in about a month. Shielding would be needed at such high speeds to deflect the dangerous effect of micro-debris.

Antimatter Drives (‘Valkyrie Drive’)
The mutual annihilation of matter and anti-matter would release incredible amounts of energy and propel any vehicle at speeds close to that of light. Three hurdles need overcoming to make this possible, firstly the creation of large amounts of anti-matter (not currently possible), which might be achieved in space borne factories several miles in size orbiting the Sun, secondly the containment of such a vast amount of energy via very powerful fields, and thirdly overcoming the mass increase problem due to Relativity Theory. The third hurdle is the most serious but could be achieved in very long craft consisting of light units stretched out like a train carriages (Project Valkyrie). A vehicle of this type has been estimated as reaching 0.9c or 90% light speed. Making Alpha Centauri a five year trip, Sirius a ten year journey and making missions to stars as far as Vega achievable within a human life time (a sixty year mission). At near light speed aging would be greatly reduced. But this still limits human activity to a tiny cluster of stars in our remote corner of the Galaxy. Such technology is unlikely before the mid 22nd century.

Part Two will explore the theory of Warp Drives and related technology.

The Possiblist Science of Space Travel

An intro to the exploration of theoretically possible space travel, consisting of some scalar milestones for a little context, with some added extraterrestrial science fiction references for a little spice.

The following is not an exhaustive list.

The Moon : Distance 400,000 km

In Fiction : Inhabited subsurface by H G Well’s grey, insect-like Selenites.

Venus : Distance closest 40 million km

In Fiction : Olaf Stapledon’s ‘Last and First Men’ has an intelligent aquatic race on Venus, Heinlein posited a primitive humanoid race there, while J Campbell an advanced one, Edgar Rice Burroughs has a multicultural mixture of both advanced and primitive civilizations, hedging his bets. H P Lovecraft populated the planet with Lizard Men. Stanislav Lem has Venus as a Post Apocalyptic world no longer inhabited. UFO contactees of the 50’s followed the Theosophical myth that Venus housed the most advanced race of our Solar System (since become ghost like). A curious mix is found in Dan Dare where a humanoid race of typical Venusians dwell in the south of the Planet while the north is inhabited by ‘little green men’ called the Treen, under the rule of the Mekon (Martian colonists??). In reality of course any lifeforms on Venus would be instantly poisoned, incinerated, crushed, dissolved and drowned! It being the most hostile environment yet found.

Mars : Distance closest 75 million km

In Fiction : The most popular early source of alien invaders since H G Wells novel War of the Worlds. Martians vary in form but are usually conceived of as small and green in most early works and this became the standard Martian . The Ice Warriors of Doctor Who were a larger variety but still remained green. Dan Dare’s Treen are standard Martians, but found on Venus (colonists??). After Ray Bradbury’s Martian Chronicles Martians tended to be recast as an extinct race of advanced culture.

Mercury : Distance closest 100 million km

In Fiction : Not usually inhabited.

Jupiter : Distance closest 650 million km

In Fiction : Once seen as a planet of primitive giants and dinosaurs in early fiction, it was slightly more realistically recast as home to an evolution of strange creatures that floated in its gaseous mass. Today even the most imaginative sci fi speculation restricts life to the Jovian Moons.

Saturn : Distance closest 1,250 million km

In Fiction : John Jacob Astor IV wrote of giant ghost-like telepaths on the dead planet before he died on the Titanic, but other than Lovecraft’s supernatural alien Tsathoggua (aka St Toad) hailing from here, few stories have populated the planet. Saturn’s Moon Titan is a more popular fictional site for life, such as Heinlein’s ‘space elves’.

Uranus : Distance closest 2,750 million km

In Fiction : Often cast as a foggy, frozen planet rarely inhabited in serious science fiction, though a notable exception being the subterranean brain that cast erotic illusions in the film Journey to the Seventh Planet and Ramsey Campbell’s Lovecraftian tale The Insects from Shaggai.

Neptune : Distance closest 4,350 million km

In Fiction : Rarely inhabited in serious science fiction other than Clark Ashton Smith’s Lovecraftian Fungoids of Yaksh.

Pluto : Distance closest 6,000 million km (0.001 Light Years).

In Fiction : A dark planet rarely cast as inhabited other than Lovecraft’s Mi-Go from Yuggoth and Silverberg’s crab-like beings.

Alpha Centauri : Distance 4 Light Years in Centaurus frame (i.e. direction of that constellation).

In Fiction : The locus of several ancient civilizations encountered early by humans. Often humanoid animal hybrid forms, notably Niven’s Cat People, P K Dick’s Insectoids, the timid Octopoids of Dr Who, and the cat-like blue giants, the Na’vi, of Avatar. Though possibly several inhabited planets?? 😉

Wolf 359 : Distance 8 Light Years in Leo frame.

In Fiction : A forward colony of the Klingons in Star Trek.

Sirius : Distance 8.6 LY in Canis Major frame.

In Fiction : Xoth, the home star of the Spawn of Cthulhu (c 200 Million BC).
Home star of Doris Lessing’s supertech Sirian Galactic Empire (100,000 BC).
Home star of Asimov’s covert antagonist race in early works (22nd Century).
The home star of the Talosians of the barren Talos IV from Star Trek’s The Cage (23rd Century).

Epsilon Eridani : Distance 10.5 LY in Eridanus frame.

In Fiction : The home star of the orbiting Space Station in Babylon Five (and at least one other fictional space station).

Procyon : Distance 12 LY in Canis Minor frame.

In Fiction : home star of antennaed blue Andorians of Star Trek.

Tau Ceti : Distance 12 LY in Cetus frame.

In Fiction : The home star of Ursula LeGuin’s Urras (a semi-parallel Earth) and Anarres (anarchist rebel colony planet) set in 21st century, as well as the scene of the Barbarella film and comics in (with a parallel chronological development to Earth).

Eridani A : Distance 16 LY in Eridanus frame.

In Fiction : The home star of the Vulcans of Star Trek.

Altair : Distance 17 LY in Aquila frame.

In Fiction : Altair IV is home to the Krell in 200,000 BC in Forbidden Planet.

Delta Pavonis : Distance 20 LY in Pavo (Peacock) frame.

In Fiction : Home star of the Dune Empire.

Fomalhaut : Distance 25 LY in Piscis Austrinus frame.

In Fiction : The teleportation target in P K Dick’s The Unteleported Man.

Vega : Distance 25 LY in Lyra frame.

In Fiction : A frequent rival humanoid empire in Sci Fi, in two tales with advanced robot technology.

Chi Draconis : Distance 26 LY in Draco frame.

In Fiction: Home star of the Minbari of Babylon 5.

Arcturus : Distance 37 LY in Bootes frame.

In Fiction : Home star of Octopus-in-a-pod from Doctor Who series.

Zeta Reticuli : Distance 39 LY in Reticulum frame

In Fiction : The first contact point with the creatures of Alien.

Pollux : Distance 34 LY in Gemini frame.

In Fiction : The home star of the alien ‘Apollo’ and other ‘gods’ in Star Trek.

Capella : Distance 42 LY in Auriga frame.

In Fiction : Home star of the female reptilian Badoon in Marvel comics (Capella II).
Home star of the seven foot warrior tribes in Star Trek (Capella IV).
Home star of a reincarnated fallen race of aliens who influence ancient history in Capella’s Exiles.

Theta Antlia : Distance 44 LY in Antlia frame (between Argo and Hydra).

In Fiction : Possible home star of the Lovecraftian Elder Things (4 Billion BC – 10,000 BC +)

Regulus : Distance 77 LY in Leo frame.

In Fiction : Home star of the Vléshga, or Shunned Ones, in M.A.R Barker’s work.

Hamal : Distance 80 LY in Aries frame.

In Fiction : Given series reference (Algol) possible home star of Daleks of Skaro in Doctor Who.

Aldebaran : Distance 65 LY in Taurus frame.

In Fiction : A frequent home star of rival empire. Possible home star of Draconians (Draconia) of Doctor Who given location. Possible home star of male reptillean Badoon (Moord) in Marvel Comics.

Zuben Elgenubi : Distance 72 LY in Libra frame.

In Fiction : A plausible home star of Dr Who’s Sontar, as Sontaran Empire never meets Daleks (this is the furthest separation).

128 Triangulum : Distance approx 100 LY in Triangulum frame.

In Fiction : The supposed home star of the Romulan planet Romulus from Star Trek.

Theta Hydrae : Distance 130 LY in Hydra frame.

In Fiction : The supposed home star of the Klingon planet Kronos from Star Trek.

Alkaid : Distance 200 LY in Ursa Major frame.

In Fiction : A very young star where life is just emerging.

Canopus (Coptic Kahi Nub, ‘Golden Earth’) : Distance 310 LY in Argo Navis frame.

In Fiction : Home star of Doris Lessing’s Sufi like Canopean Galactic Empire of 100,000 BC – 10,000 BC? and Edmund Hamilton’s Star Kings of Middle Galactic Empire (ancestors of Dune’s Muadri?) .

The Star of Dune’s Spice World Arrakis inhabited by Fremen, who are the descendents of escaped slaves from the Zensunni nomad race (c 10,000 AD), who merged with last of the Muadri (Muadri Star Empire 6000 BC – 4000 AD?).

[Dune Terran History : Prehistory 1900 AD – 3900 AD, Old Empire 3900 AD – 8900 AD, Time of the Titans (giant rebel cyborgs) 8900 AD – 9000 AD, Omnius (AI Computer and Androids / Robots) 9000 AD – 10,000 AD, Jihad Empire 10,000 AD (0 AG)– 20,000 AD, Dune Empire 20,000 AD +].

Not forgetting the Time Traveling Silver Canopeans of Time Tunnel (c 8000AD) and the desert world of Star Trek’s Canopus III with its giant intelligent slugs (23rd Century), the ones who brought the Sand Worms!??

Alcyone : Distance 370 LY in Pleiades frame.

In Myth : Home star of the Seven Maidens.

Antares : Distance 550 LY in Scorpio frame.

In Fiction : The Sun of Planet Krypton in Superman (till 1938). ‘Northern’ (Galactic Centre aligned) boundary for UFP in Star Trek (The Antares IV Fleet Yards) c. 23rd century.

Betelgeuse : Distance 640 LY in Orion frame.

In Fiction : The home star of Ford Prefect and Zaphod Beeblebrox.

Rigel : Distance 800 LY in Orion frame.

In Fiction : Home star of the Rigellians of Doc Smith’s Lensman series. The ‘Southern’ boundary for the UFP in Star Trek (Mining colony on Rigel XII).

Deneb : Distance 1500 LY in the Cygnus frame.

In Fiction : A favoured location for a rival humanoid empire by Asimov and others. Also the Silver Surfer’s home star in Marvel Comics. ‘Western’ boundary of UFP in Star Trek (Farpoint Station on Denev IV).

Dolidze 25 Star Cluster : Distance 17,000 LY (‘the furthest galactic edge object yet mapped’).

In Fiction : Perhaps the home of the Nestene Consciousness of Doctor Who (‘from the edge of the Milky Way’).

Centre of Galaxy : Distance 26,000 LY in Sagittarius frame.

In Fiction : The supposed location of Gallifrey in Doctor Who.

Delta Quadrant Centre : Distance 50,000 LY (a point mirroring Earth on the other side of Galaxy).

In Fiction : A fiction derived point, home star of the Borg in Star Trek. Also the region from which the Daemons and Osirians came in Doctor Who (‘60,000 LY away’).

Large Magellanic Cloud : Distance 160, 000 LY in the Mensa frame (14,000 LY diameter).

In Fiction : Home of Olaf Stapledon’s telepathically linked Symbiotics, the most advanced, god like multi-race in our Galaxy who terraform worlds.

Small Magellanic Cloud : Distance 200,000 LY in the Tucana frame (7000 LY diameter).

In Fiction : Home of the H’Harn telepaths in Hamilton’s Star Kings, and the blue tinged Kree of the Marvel comic series. Location of Vonnegut’s planet Tralfamadore, home of a race of robots who engineer human evolution in the Sirens of Titan, and the time traveling, fourth dimensional ‘toilet plunger’ beings of Slaughter House Five (the original inhabitants?).

Andromeda Galaxy : Distance 2.5 Million LY in Andromeda frame (220,000 LY diameter).

In Fiction : Home Galaxy of many and varied Inter-Galactic invaders, ranging from Star Trek’s supertech humanoid Kelvans, through Marvel Comic’s shape-shifting Skrulls, to Monty Python’s intelligent Blancmanges. Also the home of Outer Limit’s ‘Galaxy Being’, who teleports via radio waves (which would mean a 3 million year journey under standard physics!). This was similar to the Andromeda signals in A for Andromeda which transmitted the information for constructing lifeforms.

Triangulum Galaxy : Distance 3 Million LY in the Triangulum frame (50,000 LY diameter).

In Fiction : Home of the feathered race of the Shi’ar Imperium of Marvel Comics. Possibly the far, far away Galaxy of the Star Wars films.

Pegasus Galaxy : Distance 3 Million LY in Pegasus frame (5000 LY diameter).

In Fiction : Locus of the action in the Stargate Series, mostly pre-spacefaring societies, other than the visiting trans-dimensional Ancients and local Wraith vampire race and parasitic Goa’uld mind worms.

M81 or Bode’s Galaxy: Distance 12 Million LY in Ursa Major frame (100,000 LY diameter).

In Fiction : Home of the crystalline Tholians in Star Trek. A Galaxy also mentioned in Star Gate.

The Six Outer Galaxies of the Doctor Who series are presumed to be the above four, plus the two Megellanic Clouds orbiting the Milky Way (itself 120,000 LY x 1000 LY) which the Daleks claimed to rule, the other six ruling races (named after their leaders in order of rank) are the vaguely humanoid Trantians of the largest Galaxy (Andromeda), the cowled Zephonites of the Fifth Galaxy (Triangulum?), the veiny faced Malphans (Large Magellanic Cloud?), the bald, nobbly Celationites (Small Megallanic Cloud?), the permanatly spacesuited Beausites (Pegasus?) and the odd conical Sentrealites (M81?).

The Ford Galaxy of Mel Brook’s Space Balls is entirely fictional.

The New Phantasy Physics Blog

This Blog accompanies my new Website Phantasy Physics, which is also under development.

Phantasy Physics is a speculative and philosophical exploration of possible Science and its relation to Science Fiction.  The theories expressed here and on the website are guaranteed to be true in at least one possible universe.

The Philosophy of Time

I can now confirm I shall be running a course for the WEA on the Philosophy of Time next September.  A little early for details but for more info as it emerges email


The Fiction of Time Travel
A history of key works and ideas in fictional Time Travel, with consideration from modern science. A big subject dealing with the very foundation of reality.

The Early Period : Myth and Folklore

Transitions Between the Worlds
The earliest tales involve a journey to another world, initially the home of the gods and later faerie, on return from which after a few days years have passed on earth. Examples are found in the mythologies of most countries, but especially India and Japan, where the folk tale Urashima Tarō dates to the 8th century AD.

Comment : The universality of these tales is strange and may represent a relatively common experience. It would either seem that time runs much slower in these domains (perhaps an idea that influenced Einstein’s Special Relativity) or that the domains are outside of our normal Time and so points of exist and entry are arbitrary (an idea later used in some science fiction in the form of a higher dimension outside of our universe, typified by the film ‘The Mothman Prophecies’).

Carried by Spirits
Later folk tales describe people being carried through time by supernatural beings, the best known example being Walter Map’s 12th century tale of King Herla’s trip into the future under the influence of a supernatural Harlequin. Such tales become more common in the early modern period such as in Samuel Madden’s 1733 ‘Memoirs of the Twentieth Century’, in which a time travelling angel brings back documents from the far future (which is ironically now our past). This device is found as late as 1861 in Pierre Boiterd’s Paris Before Men’, where a demon transports the protagonist into the distant past, and of course in Dicken’s ‘A Christmas Carol’ (1843) with its time travelling ghosts. This seems to support the idea of a supernatural realm that exists outside of Time, whose inhabitants can enter or leave our domain at any point.

An interesting variant of this device is found in the tales of supernatural carriages that appear to be perfectly normal stagecoaches, but turn out to be able to travel through Time as well as Space, examples being an anonymous tale Missing One’s Coach’ from 1838. Even the Tardis can be seen as a modern variant of this, and arguably any tale involving transportation via Chrononaut’s from the future or another world can be seen as derivative of these tales.

The Sleepers
A third category of supposed ‘time travel’ involves the Rip Van Winkle device of the sleeper who awakes in the future, an old idea put to good use in William MorrisThe News From Nowhere’ (1890). But this is not really Time Travel as such.

Middle Period : Early Speculative Fiction
An intermediate period between these folklore devices and modern science fiction exists in Victorian speculative fiction. Here the format of a science fiction story is adopted but with little attempt to derive its concepts from science.

Examples would be Edward Page Mitchell’s 1881 absurdist tale ‘The Clock That Went Backward’ in which an inherited clock has the power to reverse time when it goes backwards (due to a theory of temporal non-duality superficially derived from Hegel’s Absolute), as well as Eugène Mouton’s l’Historioscope’ , in which a window to the past is used, or Mark Twain’s famous A Connecticut Yankee in King Arthur’s Court’ (1889), where a strange electric storm transports the protagonist back to the Dark Ages. Of course this also seeds our later Speculative and Science Fantasy devices as opposed to pure those of pure Science Fiction.

Later Period : The First Modern Science Fiction of Time Travel

El Anacronopete (Enrique Gaspar 1881 published 1887)

The novel, in the format of a musical drama, is the first to feature a machine that travels through time: the ‘anacronópete’ (‘that which travels against time’). The anacronópete is an enormous cast iron box, propelled by electricity, which drives four large pneumatic devices ending in tubes in order to travel, as well as powering other machinery, including something that produces the García fluid, which causes the passengers not to grow younger as they travel backwards in time. In the first act, don Sindulfo explains his theory of time: it is the atmosphere that causes time as demonstrated by the conservation of food in hermetic cans. By flying fast against the rotation of Earth, the machine can “undo” the passing of days. The book also includes a strong religious aspect including a time journey back to the Creation where the protagonists meet God!

Comment : In some ways a naïve theory (with ageing caused by reversible chemical effects in the atmosphere and the arrow of time linked to the rotation of the Earth) but in other ways insightful as many reverse time theories neglect the reverse ageing problem, and there is a grain of truth in the rapid flight theory, given Einstein’s Special Relativity, though the speed of light would have to be exceeded, something unlikely by jet power! This can be seen as a transitional novel between the middle period speculative fantasy and the later more scientific stories. Though where speculation ends and fantasy begins is a more tricky philosophical issue.

(The reverse time problem was later deployed in Philip K Dick’s 1967 ‘Counter Clock World’ and Martin Amis’ ‘Times Arrow’ (1991) where the consequence are both humorously and tragically explored. It could be argued such zones could exist in the universe or a spontaneous local time reversal might occur).

Gaspar was a close friend of the French writer and spiritualist Camille Flammarion, whose 1881 story ‘Lumen’ features an alien spirit who travels across the universe faster than light and recounts the histories of the various civilisations it had incarnated in. No time travel is involved but the story seems to have influenced Gaspar’s work.

H G Wells and Scientific Time Travel
Well’s was the first writer to apply a serious scientific thought to time travel although he didn’t take it very far. His most famous novel The Time Machine (1895), and its 1888 precursor The Chronic Argonauts, describes Time Travel in terms of Time as the fourth dimension, which we might move through as easily as we can the other three dimensions.

Comment : Today we know Wells’ was correct in his metaphysics, and in modern terms his theory would involve converting the Time dimension into something more like a Spatial Dimension which could be travelled in, in the same way we could rotate an object so its length becomes its width. Unfortunately this doesn’t appear to be physically possible because Time is a very different kind of dimension, being not only a passive flow in one direction (designated by the Arrow of Time), but also based on units of not basic integers but the square root of -1 giving it its odd properties. What that means ontologically is open to question.

Well’s scenario also presumes the future already exists in a fairly predetermined way, as is believed by those Physicists who hold to Godel’s Einsteinian Block Universe theory. But is the future open (as Quantum Theory suggests) or closed (as Relativity suggests), and if its open can we really visit it or at best visit anything more than a potential future?

Temporal Paradox in Science Fiction

Tourmalin’s Time Cheques, Thomas Gutherie (1891)
This was the first book to introduce the concept of temporal paradoxes though in a more fanciful form. Where the protagonist engages the services of an apparently paranormal Time Bank, which banks or loans out portions of time as Time Cheques. A notion not unlike the later Heisenberg’s Uncertainty Principle which loans out energy for short time periods, but taken to absurd lengths. This naturally causes several problematic paradoxes.

Comment : Modern Philosophy has since identified more serious Temporal Paradoxes that may occur during Time Travel and many of these found their way into science fiction where they were further developed. The main temporal paradoxes are the Grandfather Paradox, the Reverse Grandfather Paradox, the Predestination Paradox and the Ontological Paradox.

Grandfather Paradox : The classic murder of one’s grandfather in the past, or the killing of self as a child, but covers any paradox that makes the the journey into the past impossible.

Reverse Grandfather Paradox : Any paradox that makes journey into the past possible, such as the saving of life of self in the past allowing one to travel back into the past in the first place. Note this implies the temporal loop is a fixed part of history and so has to happen.

Predestination (or Bootstrap) Paradox : A situation of pure temporal loop such as the case where a person travels back in time and becomes their own father. Such loops seem to become permanent histories and so imply predestination with no free will, or at least a limit on free will

The Ontological Paradox : A situation in which an idea or an object has no origin. For instance a Time Traveller could journey into the future and steal the best selling book of a famous author, on return he plagiarises the book and hopes it will become a best seller, but this does not happen instead the book remains obscure until the future author discovers it and plagiarises it himself creating a best seller. In this case no one actually wrote the book it appeared from nowhere!

Many Scientists feel these paradoxes make Time Travel in possible, some logicians even believe the contradictions make Time Travel logically impossible, though this is probably taking logic too seriously. And there are perfectly logical ways of overcoming many of these paradoxes.

Not surprising more science fiction writers than scientists or philosophers have attempted to solve these paradoxes or simply just present them.

Le Voyageur Imprudent by Rene Barjavel (1943) was the first to introduce the basic Grandfather Paradox to Science Fiction in a story in which the protagonist kills his own ancestor and ceases to exist as a consequence.

This idea spawned the destructive solution to temporal paradox, the notion they actually can occur but cause harm. An idea that also spawned the idea of the Time Police, as a preventative agency, and the Time War concept invented by Fritz Leiber in the late 50s. One softer version of this idea has it that only minor destructive changes are possible not major cosmic ones (hence characters may vanish but the cosmos will not collapse into irrational chaos). In minor changes memories are also thought to vanish too, so the missing elements are never actually missed.

‘By His Bootstraps’ by Robert Heinlein (1941) was the first book to bring complex non destructive paradoxes into the genre. Here the protagonist is confronted by two rival near future selves who return to the past and trigger events that lead him into a conspiracy in the far future created by a mysterious mastermind who invented the time machine and manipulated these events. The mastermind turns out to also be the protagonist himself as the time traveller from the original trigger event and a time loop is formed. The name of the novel was taken up as an alternative title of the Predestination paradox. In a later story ‘All You Zombies’ (1959), Heinlein added further complexity by giving his traveller a sex change and having him impregnate himself in the past as well as become his own son. As the story progresses all the characters turn out to be himself.

A similar idea is found in William Tenn’s 1955 story the ‘Discovery of Morniel Mathaway’, in which time travelling historian goes in search of a mysterious historical artist, whose work he ends up creating himself.

‘The Man Who Folded Himself’, a 1973 novel by David Gerrold, took Heinlein’s ideas to even more extreme lengths when the protagonist meets multiple versions of himself and interacts with them in bizarre paradoxes. Gerrold attempts to resolve the paradoxes with the alternate time line thesis derived from the ‘many worlds’ interpretation of Quantum Mechanics.

The Parallel Worlds device is now a commonplace one in contemporary science fiction, but it isn’t the only way to resolve paradox. In fact it’s rather a poor way, only a minority of scientists seem to take the concrete ‘many worlds’ theory seriously, due to its potential infinities and conflict with the principle of parsimony, as well as the conservation of energy law, certainly John A Wheeler, who helped form the idea of a plurality of virtual quantum possibilities, didnt take it that far. Philosophers too worry about the ethical consequences of the theory such as ‘infinite responsibility’. I think the interpretation is also quite badly motivated as well, in that its an attempt to preserve a purely random, physicalist ontology. An alternative Parallel Worlds device is sometimes used in which all the alternatives are virtual or potential, until a decisive final event fixes the real Time Line, and all the alternatives may or may not vanish like dreams, forgotten by their participants (the same thing that applies to any altered time-line in the soft destructive hypothesis).

A bizarre version of the multiple virtual time lines appears in the Phillip K Dick novel ‘Now Wait For Last Year’ (1966) in which not only are alternative time-lines experienced constantly experienced, but also one key character achieves immortality by constantly jumping sideways in time and swapping with his still living alternative selves concretising them as himself. In this novel all the alternatives are remembered.

The alternative solution involves Consistent Histories, sometimes formalised as the so called Novikov self-consistency principle, named after Dr. Igor Novikov, Professor of Astrophysics at Copenhagen University. Under this principle it is actually impossible to perform most Paradoxes, because the universe does not allow them. In the strong version of this consistency law new laws of nature may spring up that prevent certain actions from happening, or improbable occurrences may intervene and prevent the event. But in its most likely form normal, consistent events will form into coherent Time Loops. For instance the example given by the physicist Richard Feynmann, where a Time Traveller attempts to kill himself as a child in the past. He takes aim with a rifle only to miss and shot the boy in the shoulder, due to a sudden shoulder pain from an old injury when a stranger shot him in the shoulder as a boy. Thus changes can be made in the past but only logical consistent changes that do not involve paradoxes. Under such circumstances it would appear that even the assassin’s trip into the past was a necessary one and so unavoidable, raising problems of determinism and free will. Is everything thus determined or is our free will just limited by this?

There is nothing in the Consistent Histories idea that says we can or cannot change the past, as either we can’t and everything is predetermined, including these logical loops or interferences, or we can change the past but only in non contradictory ways.

But even changing the past without contradictions can have serious repercussions that may be very hard to avoid. We may travel into the past to change the present, as in the Terminator films, or even to change a tragic past event, but we cannot predict the consequences of this action. We may end up with something even worse. It may even be impossible to travel into the past without changing it. In the Ray Bradbury novel ‘The Sound of Thunder’ (1952) extraordinary measures are taken to prevent changes in the past, including hunts in which long extinct species, such as dinosaurs, are hunted shortly before they would naturally die. But when a butterfly is accidentally killed, the consequences of millions of years completely changes history for the worse, including the survival of at least some dinosaurs. This story introduced the idea of the butterfly effect.

Robert Silverberg’sUp The Line’ (1969) also introduces the notion of the Time Patrol, who try to police the time traveller’s accidental and deliberate manipulations of the past and the dangerous paradoxes and consequences they create (only ultra cautious passive tourism is allowed in the story). This of course goes badly wrong.

Incidentally the use of the term UP here for going back in time is very unusual, For instance In the 1964 Outer Limits story, which became a graphic novel in 1986, ‘Demon with a Glass Hand’, by Harlan Ellison, forward Time Travel is referred to with the dimensional metaphor ‘going up’, which seems more intuitive, if the past is the foundation of the present.

But we still haven’t avoided bizarre and seemingly impossible paradoxes, Consistent Histories exclude many serious contradictions, and allow harmless paradoxes, but they do not prevent the Ontological Paradox, the production of something from nothing. A classic example of this is the 1967 story ‘The Technicolour Time Machine’ by Harry Harrison in which a post tragedy, time traveller travels back in time with a note advising his past self how to survive the tragedy. His past self keeps the note and eventually uses it to take back in time to his past self. The note therefore has no author and thus logically cannot exist, but nothing in the Consistent Histories approach or the Parallel Universe approach prevents or explains this paradox. Some regard this as evidence of the impossibility of Time Travel, others as evidence of the reality of Paradox.

An interesting treatment of time loop paradox is found in Phillip K Dick’s short story ‘A Little Something For Us Tempunauts’(1975), where not only is physical contradiction considered but also psychological, and for most of the story the actual temporal situation is a very ambiguous one.

The Technology of Time Travel
So much for temporal paradoxes, but is Time Travel actually possible? There are many methods in the literature, both plausible and fanciful, but which of these is realistic according to our current understanding? Arthur C Clarke’s Three Laws are very relevant here:

  1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right; when he states that something is impossible, he is probably wrong.
  2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
  3. Any sufficiently advanced technology is indistinguishable from magic.

This is certainly true in most science fiction , and that said we can now explore some thoughts on the possible and its limits.

The simplest form of Time Travel deploys Einstein’s Theory of Special Relativity which in this context simply states that due to the theoretical invariance of the speed of light in a vacuum and the actual geometrics of Space-Time the closer you approach the speed of light the slower time becomes. This is Time Travel in the sense that if your time slows and you move from and back to a faster time frame you will have moved into the future (note: this does not matter if the future is real or not because in Quantum Mechanical terms the faster time frame has already determined it). But is this travelling through time? In a sense it is because we cant do anything but travel through time, and in this case we just modify the relative rates, time just being a local phenomena not a universal one in Relativity Theory. To travel through time in any other sense may be meaningless, as it would mean travelling faster or slower than your local time flow which doesn’t make sense as you would no longer be in the same Space-Time (unless we invoke some kind of quantum parallel time flow).

This method is most famously featured in Pierre Boulle’s ‘Planet of the Apes’ (1963) where a near light speed space journey ends in a trip to Earth 700 years in the future. Phillip K Dick’s short story ‘A Little Something For Us Tempunauts’ (1975) also appears to be based on such a journey.

If it were possible to travel faster than light time would actually run backwards, whether it is or not is an open question. Special Relativity forbids it, but this is because of the infinities involved in the equations of a continuous mathematical model, if actual Space-Time has a quantum structure then these infinities dissappear and then the time flow shifts from a positive value through zero into a negative value (though this would require vast and perhaps impossible amounts of energy). It may be that only subatomic particles with very low mass could ever accelerated to this speed, giving rise to the theory of Tachyons (theoretically possible faster than light particles). If these could be sent back to the past and bounced back somehow, time mirrors or time communication may be possible. One alternative would perhaps be to slow light to a speed which was far easier to exceed and then in principle the same effect could be achieved. But even if we could achieve this the method would be very limited as the Chrononaut would age in reverse and so only be able to travel back within their own life span. This scenario was explored in more naïve, pre-Einsteinian form as far back as 1881 in the Anacronopete tale.

Slow Light
It is perfectly possible to slow light to the speed of an average bicycle or even stop it completely by passing it through a Bose-Einstein Condensate, or Quantum Gas, which would effectively slow light, and therefore time, to a snail’s crawl. In which case not only would we be able to in principle exceed light speed, for what it’s worth, but also experience time dilation effects at much slower speeds and great ones at high velocity. There are limits to this however.

Quantum Gas Effects
Such a gas has the odd potential to slow or even stop time within its space-time frame, as well as other useful effects, due to its production of Slow Light and the consequence of luminal invariance. Any collection of atoms, in volume of gas contained in a magnetic field, cooled to absolute zero will be void of all motion and therefore have a totally zero momentum. This means the momentum is a definite quantity and therefore their positions will be non-measurable or smudged in superposition, an Einstein-Bose Condensate or a macroscopic quantum gas. If a laser is beamed through this gas perpendicular to an arbitrary axis a selective transparency is electromagnetically induced (see technical appendix). A second laser beam fired along the arbitrary axis will be dispersed by the quantum smudge as it passes through the transparent gas, which has the effect of slowing the group velocity of the wave by over a millionth to 38mph. Thus time is effectively slowed in the gas. If the inductive beam is switched off the transparency is lost and any information in the beam is stored in the gas as excitation, until the beam and transparency is restored and the information is again transmitted. Amazingly if another Condensate has been entangled with this and the beam is restored to that instead the information carrying beam will emerge from here no matter how distant it has become.

In an extremely speculative sense we might say travelling through such a gas might lead into the future, it might even lead to the past if we moved fast enough or time slowed even further! The problem is of course is it would be at absolute zero or -273 C and its far from certain such gases can be manufactured on a large scale or exist naturally (though probably do in deep space). Even if they did exist passing through them would seem to be lethal without heavy insulation (although the near zero time rate may be of some help). Alternatively a frozen time quantum gas might also provide the ultimate suspended animation.

This may relate to the several time travel devices that involve mysterious fogs, clouds and gases that feature in many stories, themselves often drawn from folklore, most famously the origin of Buck Rogers in the novel ‘Armageddon 2419’ by Phillip Nowlan (1928) where the protagonist is frozen in a mysterious, radioactive cave gas for 500 years.

A better known way to time travel is via an Einstein-Rosen Bridge or Wormhole. In principle it is possible to curve space time so much that it loops round on itself, created a closed space-like curve, which would enable us to take a shortcut through space. By extension we can also do the same to time and create closed time-like curves. These are Einstein-Rosen Bridges.

These loops would be experienced as wormholes that leave one part of Space-Time and emerge at another (or even in another parallel universe if such things exist). It is was once thought such Wormholes might occur naturally, but it is now thought they are too unstable to exist long (though if some of the extra dimensional Superstring theories are correct, a modified Space-Time metric may allow them after all though its a long shot). One place they might form is within a enormous Black Hole, if such a rotating object was discovered it might be possible to navigate around its dangerous singularity (a hole in space in which absolutelty anything can exist or cease to exist) and enter a wormhole (a smaller or a non rotating Black Hole would destroy anything passing through it). But Roger Penrose believes singularities are so dangerous that some Cosmic Censorship Principle from getting anywhere near them. Alternatively the basic Time Dilation effect of a massive Black Hole predicted by General Relativity might be enough for Time Travel without actually entering the hole itself. The stories of Frederic Pohl explore a variety of forms of black hole exploitation. But in real life the nearest Black Hole is over 2000 LY away and creating a nearby one would seem both difficult and imprudent. Stephen Hawking also poured cold water on the idea by suggesting that Black Holes pull in so much radioactive material that they would be deadly to approach and he believes the radiation inside the Black Hole would also collapse any Wormholes that might form.

Wormhole construction on the other hand is a real possibility. Science Fiction has a long history of both space and time travel through wormholes, though they often skip the technical detail.

E. E. Smith’s Hyperspatial Tubes and the Ramsbotham Gates of Heinlein’s ‘Tunnel in the Sky’ (1955) are classic examples. While Madeleine L’Engle’s youth novel ‘A Wrinkle in Time’(1962) and Michael Creighton’s ‘Timeline’ (2003) go some way to describe how wormholes could be generated in order to travel through Time. The former suggesting Space-Time can be ‘pinched together until joined by a bridge’, but goes no further. Carl Sagan’s ‘Contact’ describes spatial Wormhole physics in great detail, but although temporal anormalies are described no temporal Wormhole physics is covered.

In real life physics howver several papars have been written about how to form such temporal Wormholes. In short transient micro-wormholes appear spontaneously all the time at the quantum level and only need enough energy to open them up wider. These can be achieved in theory by a vast cyclotron. Such wormholes would still be small and unstable but could be expanded and kept open by negative energy or matter, which ‘anti-gravitates’. Such stuff is also producible from sub atomic, quantum vaccuum states via the Casimir effect (see technical appendix). This process should create a spatial Wormhole. To turn it into a temporal Wormhole we simply rotate the ends of the tunnel at different velocities which creates a Time Dilation and turns the Wormhole into a Time Tunnel. Again though Hawkings suggests quantum virtual particles will build up in the wormhole and collapse it before it can be used, though others believe this radiation will just leak out.

Note that a Time Tunnel can never connect to a time before it has been constructed however and so is effectively limited to forward time travel or backward only with its own lifespan.

A similar Time Travel process is actually being developed now with more simple techniques than a Wormhole. The Mallet device, named after its developer Prof Ron Mallet, is predicted to work by using the Slow Light mentioned earlier. In this system a strange property of Slow Light is exploited, its tendency to gravitate more the slower it moves (energy gravitates just as matter does). This means by creating a double vortex of Slow Light, moving in opposing directions, a gravity well of such intensity could be created that it functions like a small Black Hole in producing Time Dilation. As with Wormholes, the energy required to transport a macroscopic object would be vast, but on a microscopic scale could be achievable even today, allowing sub atomic particles to time travel, and perhaps allow a temporal communication device of time telescope to be constructed. As before this will only work within the time span of the device, connecting its past self with its future self, and not outside those limits. But one weird possibility then would be a far future contact with a technology that was even more advanced in Temporal Engineering!

More Speculative Means

This is the limit of current physics but more speculation based on the frontiers of science is still possible. A popular means of Time Travel found in science fiction and typified by the Dr Who notion of the Tardis is a moving outside of our Space-Time continuum at one point and renentering it at another. While the fictional Tardis technology is closer to magic than science (and reflects the kind of folktales of otherworlds we started with) this idea remains in the bounds of possibility. But how it would be done is more difficult to imagine.

Science Fiction often refers to Hyperspace as a region outside of our universe, arrived at in a wide variety of ways, it was first described in Nelson Bond’s The Scientific Pioneer Returns’ (1940) and further developed by Isaac Asimov in his Foundation stories (1942-1944). It soon became a staple of science fiction, and was slightly modified in various tellings, such as as the Subspace of the Star Trek series. The original notion was of a spatial shortcut outside of normal space to over come the problem of distance and the light speed limit. But authors soon realised it could be used for Time Travel as well, given the unified Space-Time continuum, and initiated a new form of Time Travel (also inspired by folktales). But although contextualised within the closed, curved universe of interpretations of Relativity Theory it is purely a fictional notion, or at least has no basis in modern physics, in which there is conventionally nothing outside of the Space-Time continuum.

The folklorish element of the idea was revealed early in
The Mystery of Element 117′ (1949) by Milton Smith, where a ‘hyperplane of hyperspace’ is discovered to be the realm of the dead!

But are there any indications of its possibility in cutting edge physics? One area is in M-Theory, a synthesis of all the String Theories, which postulates an extra extend dimension (which we can call the fifth dimension for convenience, the other multi-dimensions of String Theory being micro compact) which seperates an indefinite number of other universes (now concieved of as lower dimensional membranes). This seems very much like Hyperspace, but the main difference is none of the forces of our universe can travel in this dimension apart from gravity (whose assymetric strength in our universe is explained by it leaking into this dimension). Therefore we could never enter it it seems. The only concievable way being if we could some how code the structure of the matter of an object into a set of information states and transmit it as gravity waves through M-Space, perhaps bouncing it off another membrane and returnining it to our universe at another point and recreating the original material object. In otherwords a form of spatio-temporal transfer known in science fiction as Teleportation. An idea invented by Conan Doyle in his ‘Disintegration Machine’ (1927).

But if we are to use Teleportation (a highly problematic idea in itself given the uncertainty principle re the exact atomic configuration of any object) we might have to do it in our own local universe, especially as it seems to require a sender and reciever unit (contra Star Trek). We could use light speed particles to travel into the future or tachyons to travel into the past in this way. The quantum problem could be solved by using entanglement, non-locality and Quantum Teleportation which may have its own temperal features.

Much of the problems at this frontier are borne from the fact we do not yet know how to combine Relativity Theory and Quantum Theory. And of course we can’t exlude some unknown physical like domain beyond normal Space-Time yet to be discovered.

Time and Consciousness
A radical departure form this purely Physical Science is also possible. Many science fiction tales employ the idea that there is some psychic or consciousness based element to Time Travel.

The most famous of these is Slaughter House 5 by Kurt Vonnegut (1969). Here the protagonist becomes ‘unstuck in time’ during his various crisis moments, and then experiences his life events repeatedly in a random order, which are constantly identical. This seems to be due to his contact with perceptually time travelling aliens who experience life in four dimensions, and confirm it’s Predetermination. The protagonist adopts and preaches the alien fatalist creed. The idea is based on Einstein’s Block Universe but the aliens seem to have a temporal sense even if they cant physically travel in Time. There is also uncertainty as to whether the Time Travel involved with the protagonist is physical or perceptional.

More dramatically Time Travel is achieved by hypnosis in several stories, most notably in Jack Finney’s novels, such as ‘Time and Again’ (1970), but also in Richard Matheson’s ‘Bid Time Return’ (1975). A method developed in J. B. Priestley’s book ‘Man and Time’

In the ‘Time Traveller’s Wife’ (2003) by Audrey Niffenegger, the protagonist randomly travels through time due to some ‘genetic disorder’, perhaps implying a psychical element to the process.

In these tales the method is perceptual but the travel appears to be physical. This could be explained by some form of Idealist Philosophy in which reality is shaped by consciousness, which would be arguably completely at odds with Modern Science, or may just be based on a more mysterious notion that the Laws of Physics are manipulatable by mind. I’m sceptikal about both. If this were possible why don’t we see it more often.

One interesting version of a more plausible perceptual Time Travel is found in Daphne du Maurier’s ‘The House on the Strand (1969) where a drug enables the protagonist to mentally travel in time, becoming a ghost like being in the 14th century percieving but unpercieved, and shadowing his doppelganger in that time, while his body moves around unpercieving in the 20th century! A whole genre of psychedelic time travel follows from this.

Certainly there is a very real tradition of apparently Paranormal Time Travel , the classic cases involving a mysterious turn in the road leading to a building in the past, such as the famous case of the British holiday makers in France who ended up in a 19th century hotel (1979) or reports of an experience of a bombing raid in Germany (Hutton and Brandt, Altona Ship Yards, 1932) eleven years before it actually happened. Of course we cant exclude hoaxes in these cases but they are comparitively common in Fortean Literature and in one case (a patient of Dr Raul Centeno, Peru) involved measured physical effects, namely a right side paralysis following an alleged encounter with a 17th century log cabin (with measurable left hemisphere electrical abnormalities). These stories are very odd but perhaps the most perplexing being the report from Air Marshal Victor Goddard to have flown over and disused Drean airfield in 1935, following a traumatic flight through some ‘strange brown clouds’ and an electrical storm, and seen it as it would be in service in 1939 (complete with changed uniforms and new style aircraft unknown in 1935). The ground crew oddly failing to see Goddard’s plane. Given Goddard’s other alleged experiences of prophetic dreams, ghosts caught by him in photographs, and UFOs investigated, perhaps we could dismiss him as a yarn teller with some of the others, but there is a definite common pattern to these experiences (even though some of Godard’s descriptions are reminiscent of the science fiction of his time).

More subtle perceptual changes involve odd shifts in time where the time experienced seems to expand or contract according to need, not in terms of simply duration but in real time, often in moments of intense concentration or involved group activity. I myself experienced something similar as a teenager when late for school and encountered a stranger who told me to forget about time and lateness and to concentrate on the conversation as we walked briskly. In the event a normally 20 minute journey was achieved in 10 minutes. This may relate to Henri Bergson’s idea that it was subjective Duration that was the real essence of Time, with objective Chronology a mere abstraction. But that leads off into more complex Existential notions of Time and Consciousness.

Perhaps Consciousness itself, or the potential for it in mental impressions or perceptions, is actual a maleable, psychic continuum much like Space and Time, and interlinked with them in a broader 6th dimensional Space-Time-Psyche (allowing for M-Theory), in which perceptual malleability is interlinked in the same way the malleability of Space and Time are. This would certainly explain another common Fortean experience of meaningful coincidence or Synchronicity, tying apparently random events up with states of mind, and may open up whole new psychic domains. But such things may be beyond our current understanding and takes us back to where we began in the magical folklore of our ancestors.

A final observation is if Time Travel is possible they must be here now, so where are they? A thought that opens up interesting experiments (including one undertaken this week …..)

Technical Appendix

Relativity Notes

Time Dilation under Special Relativity can be understood geometrically in terms of the Pythagoras Theorem, where the long leg represents the velocity of the vehicle as a vector, the short leg represents the velocity of a photonic oscillation within the vehicle (the timer pulse) and the long hypotenuse represents the real vector velocity of the photon in the on-board timer as the vehicle carries it through space. As the speed of light is invariant in a vacuum the hypotenuse must stay a constant length, but as the long leg approaches a similar length (the vector velocity near C) in order to preserve the geometry the short arm must shrink by increasing factors (the photon gets slower) and so time slows (relative to an external observer but not the travellers who are unaware of the motion). The whole effect depends on light speed, invariance and the laws of geometry. The infinities are produce by the Pythagorean Equation: A squared = C squared minus B squared when A squared reaches zero at light speed and is used in division (and so may be a mathematical artefact). A quantised Space-Time (a jigsaw of ‘space-time bits’) would need a different maths. There is a parallel with solutions to Zeno’s first Paradox of Motion here.

Time Dilation under General Relativity can be understood in terms of an extension of SR and the thesis of the Space-Time continuum. In SR mass increases at near light speed due to the principle of the conservation of momentum (p) between interacting frames of reference and the relatively differentiating momentums within those frames (p = m.v, where one relative velocity (v in m/s) has shrunk, due to the time dilation, it’s mass (m) must increase). When this is generalised in GR we can see that mass increases as time dilates, and given the relation of Space and Time as a single continuum we can say that increased mass or gravitation (space curvature) results in slower time (time curvature). Were as space curvature causes gravitational acceleration time curvature will cause temporal deceleration due to the negative value in its the Space-Time maths.

Energy as a gravitational factor can be similar understood as a correlation between the mass increase at high velocity and the increased kinetic energy with that velocity. When generalised we can say that energy increase produces increased gravitation, or curves Space-Time, just as much as matter does (the two being shown to be equivalent in the famous E = M.C squared formula). The Gravitation of the Earth can be shown to have a tiny factorial determined by its internal heat!

Quantum Notes

Superposition occurs when particles in quantum flux exist in more than one place at the same time spread out in all possible positions, or are travelling along all possible paths between source and destination. This is the normal state of matter and energy at the quantum level (and according to Decoherence Theory the normal state of matter and energy at all levels) until a measurement connects it’s domain with the rest of the universe, forcing it into a consistent, classical state for observers in that locality with a specific history. In Quantum Theory the future is indeterminate and probablistically random in this way until experienced (though a variety of virtual or potential futures may exist and be capable of interaction). This is at odds with Relativity Theory Cosmology which implies the Future is predetermined or fixed.

Casimir Effect Note

The typical example is of two uncharged metallic plates in a vacuum, placed a few micrometers apart, without any external electromagnetic field. In a classical description, the lack of an external field also means that there is no field between the plates, and no force would be measured between them. When this field is instead studied using quantum measurement, it is seen that the plates do affect the virtual photons which constitute the field, and generate a net force—either an attraction or a repulsion depending on the specific arrangement of the two plates. Although the Casimir effect can be expressed in terms of virtual particles interacting with the objects, it is best described and more easily calculated in terms of the zero-point energy of a quantized field in the intervening space between the objects. This means polarized energy is being produced from the void potential, in which all polar forces cancel to zero (the vacuum is thus not empty but rather is near infinitely full of opposing forces negating each other -1 and +1 = 0), which can be detected as virtual quantum particles. In addition to normal positive matter and energy, which gravitates, some negative matter and energy (not anti-matter) will also be produced, which ‘anti-gravitates’, and this is harvestable.

Quantum Gas Notes
Wave Velocity – This has two components, the phase speed and group speed. The group speed is the speed of propagation of the wave (the speed of the light beam or photon for instance), the phase speed is the speed of the phases within the wave (the line followed along the curves). All material that is transparent allows waves to pass through it but will modify the wavelength slowing the phase speed of the wave, thus causing Refraction and/or Reflection.

Transparency – Most Transparency effects are caused by the random distribution and spacing between atoms, thus solids are mostly opaque and gases are mostly transparent. One exception is glass which has a very random structure due to melting and rapid cooling (it can be made more opaque by cooling slowly and allowing ordered crystals to form). But atomic structure also plays an important role too. Different materials interact with light differently, depending on the nature of their atomic structure and the wavelength of the light (usually mixed). Some absorb light, others absorb and release it later, some scatter it or let it pass through unabsorbed and unscattered, while others reflect it, and all to varying degrees (plus various wavelengths interact differently producing colour). Any material that can coherently transmit all the light is transparent (if only on some wavelengths it’s a transparent colour filter), or if it only transmits defuse light it’s translucent.

Electromagnetically Induced Transparency – Atoms in superposition of the appropriate kind will make their substance transparent by creating a destructive interference pattern preventing photon absorption. This set up occurs when a coherent laser beam is streamed into the substance.

Refraction – The wavelength change that occurs with a wave’s transition across two media, with constant frequency, causes a change in the phase speed of the wave, while its group speed is unchanged. At angles greater than zero this also causes the direction of the wave to change (because one end of the wave-front, or ripple, enters before the other giving a varied speed across the wave-front and thus twisting it round). Beyond a critical angle Refraction becomes total internal Reflection.

Reflection – Defuse Reflection is produced by the photonic emissions of resonantly vibrating atoms or electrons in an appropriate medium on the incidence of a light beam. If Refraction occurs half the emission will follow the refraction while the other half is reflected as randomly scattered light. If the reflected emission is coherently aligned a spectral reflection will occur (mirror image). If the Refraction incident angle passes a critical angle Refraction become Reflection and total internal Reflection is achieved.