The concept of time travel is fascinating, but it's important to note that our current scientific understanding and theories do not provide any confirmed method for practical time travel. The possibility of meeting yourself as an adult or teenager through time travel remains speculative and exists mostly within works of fiction.
In popular fiction, various theories and mechanisms for time travel have been proposed, such as wormholes, time machines, or manipulation of spacetime. However, these are purely hypothetical at present, and their feasibility within the laws of physics remains uncertain.
Regarding the effect on the universe or timeline, it's worth mentioning that time travel, if it were possible, could lead to several paradoxes and logical inconsistencies. One example is the "grandfather paradox" where a person travels back in time and does something that prevents their own birth. This creates a contradiction: if the person was never born, how could they travel back in time in the first place? Resolving such paradoxes requires complex theories involving alternate timelines or the idea that the past is fixed and cannot be changed.
Speculating on the consequences of time travel is highly speculative and depends on the specific theoretical framework. Some theories propose that the timeline would be altered, creating a new branch of reality or a parallel universe where the time traveler's actions have their own consequences. Others suggest a deterministic view where time travel was always part of the timeline, and the actions of the time traveler were predetermined.
However, it's important to reiterate that time travel is currently beyond our technological capabilities, and any predictions about its effects are purely speculative and hypothetical.