I do remember some theories concerning relativity suggesting some sort of motion in space might allow time travel if space-time geometrics are possible.
These doctrines of Lotze - though pronounced with the distinct and reiterated reserve that they did not contain a solution of the philosophical question regarding the nature, origin, or deeper meaning of this all-pervading mechanism, neither an explanation how the action of external things on each other takes place nor yet of the relation of mind and body, that they were merely a preliminary formula of practical scientific value, itself requiring a deeper interpretation - these doctrines were nevertheless by many considered to be the last word of the philosopher who, denouncing the reveries of Schelling or the idealistic theories of Hegel, established the science of life and mind on the same basis as that of material things.
The principle therefore of these investigations is opposed to two attempts frequently repeated in the history of philosophy, viz.: (1) the attempt to establish general laws or forms, which the development of things must have obeyed, or which a Creator must have followed in the creation of a world (Hegel); and (2) the attempt to trace the genesis of our notions and decide as to their meaning and value (modern theories of knowledge).
Let us consider some common phenomena in the light of these rival theories as to the nature of matter.
Tables, not, as tradition would have it, imported from Greece, but the natural and spontaneous product of ancient Roman customs, and many other similar theories were discovered by Vico, and expounded with his usual originality, though not always without blunders and exaggerations.
How would you define theories? Add your definition here.