The Taurus and its energy source stay in one place. In order to move through time and space, the time traveller needs to have physical contact with a time phone, which is controlled and tracked by the Taurus. Time travel is only possible, however, when the Taurus has enough energy and when there is a strong enough carrier signal. As Jack and Angus have discovered, the signal can be as unpredictable as the weather. Periods of time open up and then close, like shifting sands, so that no location is constantly accessible. Then there is the ‘Armageddon Scenario’, which suggests that, if you revisit the same point in space and time more than once, you dramatically increase the risk of a continuum meltdown. Imagine space and time as a piece of tissue paper – each visit makes a hole in that tissue paper, as if you had pushed through the tissue with your finger. The tissue would hold together for a while, but with too many holes, it would disintegrate. It is dangerous, therefore, to repeat too many trips to exactly the same point and the Taurus will seek to avoid such scenarios. The precise parameters of this constraint are not known and have not, of course, been tested.