One of the most commonly asked questions in time travel would probably be – Is time travel possible, and if so, how do you build a time machine to transport the occupants to another time?
I’ve got another question which I think should also be considered: How does a time machine move itself (in time)?
For a time machine to work it needs to move itself in time as well as its inhabitants because otherwise it would be a portal of some ilk which requires a similar device at the ‘other end’. In such a portal, a temporal field modifier (or whatever!) is generated by the device and applied to the time traveller to be. But in a ‘regular’ time machine, the force is generated internally and applied to internal occupants, moving both time traveller and machine.
But the idea of a time machine moving itself is almost a literal example of “bootstrapping” (though paradoxically, not a paradox!). Bootstrapping is a little bit like living in the ‘cartoon world’ where Newton’s third law doesn’t exist (“For every action there is an opposite and equal reaction”).
This is where you can sit on a yacht and blow yourself along, or as the name suggests, lift your whole self up by tugging on your boot laces (or straps). Or, as it would seem here, lift a time machine into another time by using an internally generated force.
Further, if a time machine remains moves through time then it is effectively present in space through all of the intermittent time steps between the moment of departure and the time of arrival. You’d think this would increase the chances of us coming across a time traveler (or at least his time machine), though they seem to be in short supply…
But maybe there is a paradox. Saying that a time machine will take you some place else in time but not actually move itself it much like saying you’ll get into a car which will take you somewhere, but it doesn’t move itself because it has no wheels. (Come to think of it, that does sound like my own car!).
So we’ve some full circle; a time machine needs to be transported. But how?