The idea of time travel and its implications on parallel universes and alternate timelines is a popular subject in science fiction. While it is speculative and theoretical, let's explore two potential scenarios based on your example:
Multiple timelines or parallel universes: According to one theory, each change made through time travel could create a branching timeline or parallel universe. In this case, if a person from the future came to our time and introduced advanced technology, it could lead to the creation of a separate timeline where the future unfolds differently. This theory suggests that any change in the past would create a new timeline that diverges from the original, with its own unique events and outcomes.
Single timeline or "canon" events: Another theory posits that time travel operates within a single timeline, where any changes made in the past are already part of history and do not create new timelines. According to this perspective, if someone from the future introduced advanced technology, it would be considered a "canon" event—already part of the predetermined timeline and history.
It is important to note that the concept of time travel and its impact on alternate timelines is purely speculative and subject to various interpretations. There is no scientific consensus or empirical evidence to confirm the existence of parallel universes or how time travel would truly function.
Different works of fiction and theories propose different models for time travel, resulting in a wide range of possibilities. Ultimately, until time travel becomes a scientific reality, the nature of its impact on alternate timelines and parallel universes remains a matter of speculation and creative interpretation.