The possibility of time travel is still a subject of scientific exploration and debate. time travel has not been proven to be possible, and it remains purely speculative. However, I can provide you with an overview of some of the concepts and theories associated with time travel.
There are various theories and hypotheses put forth by physicists that suggest the potential for time travel, such as the concept of wormholes, which are hypothetical tunnels in spacetime that could connect different points in time as well as space. These wormholes could potentially allow for travel between different periods in time.
Regarding your question about people or animals who have died, if time travel were possible, it would depend on the specific theory or model of time travel being considered. One possibility is that traveling back in time could create a parallel timeline or alternate universe, where events unfold differently from the original timeline. In such a scenario, the deceased individuals would remain dead in the original timeline, but the time traveler could encounter alternate versions of them in the new timeline.
Another idea is the concept of a "closed timelike curve" proposed in some theoretical models, which suggests that time travel to the past might be possible within certain limitations. However, these models often involve the notion of consistent time loops, where events that occur in the past have already influenced the present and future. In such a case, the time traveler's actions in the past would have already accounted for the existence or absence of deceased individuals in the future.
It's important to note that these theories and concepts are highly speculative and remain largely within the realm of science fiction. The scientific community is still exploring the fundamental nature of time and the laws of physics, and more research and evidence are needed to determine the actual feasibility and mechanics of time travel, if it is indeed possible at all.