Time travel requires huge amounts of power. This was illustrated in several Doctor Who episodes when the true power of the TARDIS was glimpsed, such as pulling a spaceship away from a black hole or indeed pulling the planet Earth halfway across the galaxy. To give you an indication of the complexity of time travel, a working TARDIS probably would have sufficient power to do those things  scary eh?
Anyway, what about a fun answer to time travel (we got the idea for this by thinking about the TARDIS).
The Black Hole Containment Device
For a
little lighthearted relief, to achieve the fantastic energies required for
translight travel one possible huge power source can be built by tapping the
energy of a black hole. To trap a black hole and use it a way must be found of
containing the black hole inside a field of some sort. This can be done as
follows. Any black hole is completely defined by three quantities: its mass, its
charge, its angular momentum. The mass is simple, and for our purposes the
bigger the better! The black hole can be charged since the electrostatic field
equations are not subject to relativistic corrections etc. Electromagnetic
fields all travel at light speed anyway! Next is the angular momentum. Now
computer simulations have shown that a rapidly spinning black hole turns into a
torus or doughnut. Then a large metal rod can be passed through the middle. At
the centre of the torus (the Eye of Harmony), we are outside of the event
horizon and gravitational fields are very low so the rod will not be torn apart.
The black hole must then be charged by firing millions of tonnes of charged
particles at it. Then an opposite charge must be maintained on the rod and the
black hole is captured around the metal rod. Two huge fields must build around
the black hole to stop it from sliding up and down the metal rod.
How to use the Black Hole Containment Device
To gain energy you use the rotational vortex method of Roger Penrose, and by
using reusable matter to get the energy you can tap off as much as you like.
With such a power source set up, one can build a dimensional collapse which
enables you to shrink the apparent size of the blackhole machine. This will
also mean that the mass of the black hole will fall for external observers.
Another way of solving the mass problem is to use Higgs Boson particles to
negate mass, since the Higgs Boson is generally believed to be the origin of
mass. Then the device can become part of a normal spaceship. One can also change
the relative time advancement rate of the blackhole region of space and so
gain vast amounts of energy from the Hawking radiation that Black holes give
off. This way the Black Hole loses mass and so you can turn the entire mass of
the Black Hole into energy. Also the Black Hole then maintains it's own
containment field. The important point is that one can set up the energies
needed to cause the quantum fluctuations in general relativity and so tunnel
across the translight barrier. The universe suddenly becomes yours for the
taking. A NASA space shuttle fitted with a BH device becomes more powerful than
Darth Vadar's Death Star!
Hence the job of a civilisation is to find a rapidly spinning Black Hole in
order to build the first BH containment field. Or make their own via some star
collapsing technology etc
Black Hole Containment Diagram
Below is the original diagram of the Black Hole power source that
we believe is the only viable way to generate the huge energy requirements that
make time travel a practical possibility. Note that we have NOT required the use
of either magnets or power crystals! The text at the bottom says..."The torus represents the event
horizon of the circular singularity (note that this is NOT a point singularity
as possessed by a conventional black hole). Around the setup (but not shown for
clarity) is the equipment used to collect the VAST amounts of energy resulting
from Hawking radiation (as described by our Time Travel Energy Equation in the mathematics area)"
Note the rather small size of the Starship Enterprise on the same scale!
