Objections to Time Travel Theories

Table of Links

I. Introduction

II. Pseudoscience

III. Unidentified Assumption

IV. False Assumption

V. Objection

VI. Conclusion and References

V. OBJECTION

One might object that the argument in this paper rests on the assumption that quantum mechanics implies indeterminism. Proponents of a deterministic block universe, including those who hold the Many Worlds Interpretation (“MWI”) of quantum mechanics and those who assert that the quantum wave state of every system always evolves linearly and reversibly, might argue that both statements C) and D) are true, with AliceX detecting the object at position X and AliceY detecting it at position Y. Eq. 1 is essentially an assertion of determinism, that if no changes are made to the past then no changes will be made to the present. According to MWI, Alice may indeed find herself in a different branch of infinitely many present universes, but the present multiverse itself will not change if she makes no changes to the past.

This objection fails. For instance, what would it mean for Alice to find herself in a branch of the multiverse in which, due to chaotic amplification of some tiny interaction, she decides against time travel, or isn’t born? Rather, the point of Section IV is that Alice cannot travel into the past without changing what she perceives as her present universe. Because proposals for time travel all inherently depend on the applicability of Eq. 1 to the time traveler’s own perspective, these proposals fail and fall outside the scope of scientific inquiry.