The concept of time going infinitely backward is a theoretical idea and not currently supported by scientific evidence. In our current understanding of the universe, time is believed to have originated with the Big Bang, which is thought to have occurred approximately 13.8 billion years ago. Before that event, the concept of time as we know it may not apply.
Speculating on the existence of an infinite number of alternate timelines or new timelines being created every second in a backward-infinite time scenario is purely speculative and falls into the realm of science fiction. While there are various theories and hypotheses in physics that explore the possibility of multiple universes or branching timelines, such as the concept of a multiverse, these ideas remain largely speculative and have not been proven.
It's important to distinguish between theoretical possibilities and what is currently supported by scientific evidence. While time travel is a popular theme in fiction and has been explored in theoretical physics, there are significant challenges and paradoxes associated with it. Theoretical models that allow for time travel, such as certain solutions of general relativity known as "wormholes" or "closed timelike curves," are highly speculative and not yet well understood.
It's worth noting that even if some form of time travel were to be theoretically possible, it would likely involve extremely advanced technology and understanding that is far beyond our current capabilities. As of now, time travel remains purely speculative and has not been demonstrated or achieved in practice.