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.
To this attitude he offered uncompromising opposition, and by the synthetical production of numerous hydrocarbons, natural fats, sugars and other bodies he proved that organic compounds can be formed by ordinary methods of chemical manipulation and obey the same laws as inorganic substances, thus exhibiting the "creative character in virtue of which chemistry actually realizes the abstract conceptions of its theories and classifications - a prerogative so far possessed neither by the natural nor by the historical sciences."
How would you define theories? Add your definition here.