Like I have said severaly, if ET moves from stars to stars by waving a magic wand, then there is no purpose of a spaceship! Ironically this undermines the only objective evidence a UFOlogist offers for the claim that we are being visited by ETs. We have seen a few models of the universe to check what role a spaceship might play in those models. None of those models,  eg 'holographic universe' gives a straightforward need for a spaceship. Models of universe that purports that we are somehow 'omnipresent' or 'we move by magics' tends to underminethe very need for a spaceship or gives only far fetched explanations, like the ones I have tried hard to offer!

It should be clear that we don't move my 'magics'. If we did that, we might have already moved to stars by now! Elsewhere, I have explained why the claim that this planet is a prison, or something like that is untenable. It is a mere ad-oc to explain why we don't easily move to stars if motion to there is by magics. The best explanation for why we don't move to stars is that we don't have the technology for it yet. There is no bizarre way of movement! Before we developed planes, ships and cars, we could not easily move to far regions of the world. There was no 'magic' way round! There is no reason to think that the case is different for interstellar travel. At least not, if we are yet to demonstrate such a way of 'magical movement' in small scale. Way before man made a plane, he could watch birds and be ascertained that, though no such means for flying a human was there, it was at least possible, as they could see instances where they were achieved. Same applies to all forms of transports.

Movement to stars must be done through speeds far faster than the speed of light. This poses a big challenge as the laws of physics known so far prohibits such a movement! The only way to understand such is to try to explain Einstein's relativity in such a way that it is contingent on something in space that can be avoided. Fortunately, not only is such explanations possible, they are plausible and very rational!

There are many ways of explaining relativity. In one of them, it is seen to arise from electromagnetism. Motion of charges results in a force in between them termed 'Lorenz Force'. This slows the vibration of charges and hence 'time dillation'. So if particles have no fundamental charge, then there is no reason to think that it is subject to relativistic effects. One catch is that such particles cannot be visible (light is electromagnetic). They belong to the same category as 'Weakly Interracting Massive Particles' (WIMPS), the candidates for the so called 'dark matter'. As a rough explanation, the slowing of charges is due to 'friction in the medium in which light propagates as a wave.' This opposition from the medium is the one that 'converts the kinetic energy of electron into light energy' much the same way the air resists a speeding pebble to form a buzzing sound. So if a particle does not interact with that medium, then it is not subject to the same limitations much the same way light, unlike a pebble is not much slowed by the air in that it interacts more weakly with the air.

But I like to zeroin on a more teleological explanation for relativistic effects. Ask why must  an atomic clock slow down when it is moved? The answer is that if it doesn't do that, then the electrons orbitting the atom will be slung away from the atom like bullets off a machine gun! We capture this by a number called 'fine structure constant'. ( A)

A=q^2/hc

q=charge of an electron

h=planck's Constant

c=speed of light

This value is fine tuned in amazing way, to make life possible in our planet! This has drove physicists to wonder if the universe we see is the only one. There must be, they think, several other universes with different fine structure constants so that we are 'naturally selected' in a universe that happens to be condusive for light. But if we were to accept this 'many universes' explanation for fine tunning, ask what is it that varies in the right hand side of fine structure constant ? The easiest to explain is the speed of light. This is because we already know that speed of light varies from medium to medium. It varies from glass to water to air etc. So it is a matter of thinking of 'vacuum' as a medium on the same par with air, albeit a more tenuous, a view that is extremely easy to accept. Infact it is already seen as 'matter-untimatter potential'. This can undergo polarization in the vicinity of charged particles. This us termed 'vacuum polarization' and is similar to any other polarization in a medium.

 So think of space as to be interlaced by mediums of all manner of properties. In each medium, light propagates at a unique speed. In a medium in which light propagates much faster, everything moves similarly faster. If light propagates at twice c, a rocket similar to one on earth will move at twice the speed it moves on earth and so forth. The interlacing of media can be understood by considering the 'molecules of the media' as to have wave-like properties, as taught by quantum mechanics. So the interlacing is in much the same way radio waves of varying frequencies are interlaced in the same space, so that you can tune to different stations that seem to be on the same place but without interfering with each other! Though more challenging for solids or liquids, it is a piece of cake for waves. But this is not the only way for understanding interlaced realities.

The need for spaceship is now straight foward. Things moves the usual way even in those other 'universes'. It is only much faster! So the spaceship can even be the usual rocket but using a more reliable technology, eg a plasma truster, which collects plasma that is abundant throughout the universe and use it as fuel.

'Movement' to this other plane of reality will involve changing all the atoms of the crew and that of the space ship! This may be possible if we position our spaceship strategically so that it lies on a special place in space where matter from this other plane passes by. This matter is akin to 'dark matter' . It works much like raising the temperature of an object. If a warm object touches a cold body, the latter will soon become warmer and the former colder. So it is an 'exchange of properties'. Similarly if a piece of matter that has a property that enables it to interact with a medium that allows must faster than light travel comes close to the usual matter, they may 'exchange the properties'. This 'exchange of properties' is very common. When a moving billiard ball knocks a stationary one, they 'exchange the momentum' so that the moving one stops and the stationary one begins to move.