The consequences of meeting yourself from the future or past in a hypothetical scenario of time travel can vary depending on the assumptions and theories one considers. Here are a few possibilities:
Paradoxes: One potential consequence is the creation of paradoxes. The grandfather paradox, for instance, arises when a time traveler goes back in time and does something that prevents their own existence. This leads to a contradiction because if they were never born, they couldn't have traveled back in time to prevent their birth. Resolving such paradoxes is a topic of speculation and different theories propose various solutions, such as the Novikov self-consistency principle or the branching of timelines.
Causality violations: Meeting yourself from the past or future could potentially lead to causality violations, where events occur in a sequence that defies the usual cause-and-effect relationships. This challenges our understanding of how causality operates and could disrupt the consistency of the timeline.
Information and knowledge: Interacting with yourself from a different time could result in the exchange of information and knowledge that you did not have in your original timeline. This could have implications for altering the course of events or influencing future decisions based on foreknowledge.
Personal identity: Meeting yourself from a different time raises questions about personal identity. How would you perceive yourself? Would your future or past self be fundamentally different from your current self? This raises philosophical questions about the nature of identity and the continuity of consciousness.
It's important to note that these consequences are speculative and based on hypothetical scenarios of time travel. As of now, time travel remains purely theoretical, and our understanding of its potential consequences is limited by the current knowledge of physics.