Electrons moved in two dimensions when influenced by a magnetic field, hinting at how a similar effect would occur in the fourth dimension.

Here it is explained that they were once human beings ... Fortunately, although the fourth episode is missing, the all important sequence showing the change of the First Doctor into the Second ...

From 2-D to 3-D An early attempt to explain the concept of extra dimensions ... the square conceives the possibility of a fourth dimension. He even goes so far as to suggest that there may be ...

His absence is explained by having the Doctor locked up ... Vicki explains to Steven that TARDIS stands for ‘Time and Relative Dimensions in Space’. This is the first time that ‘Dimension ...