**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!