According to our current scientific understanding, time travel to the past is considered to be impossible, at least in the conventional sense. There are several key reasons and limitations that prevent us from traveling backwards in time:
Causality and Paradoxes: Time travel to the past introduces the potential for paradoxes, such as the grandfather paradox or bootstrap paradox, which involve logical contradictions and violations of causality. These paradoxes arise when the effects of time travel create inconsistencies or loops that disrupt the sequence of cause and effect.
Conservation Laws: Time travel to the past would need to overcome various fundamental physical principles, such as the conservation of mass-energy and other quantities. The ability to change events in the past could potentially lead to violations of these conservation laws.
Time as a Fourth Dimension: Time is often considered as the fourth dimension of spacetime, and it is intricately linked to our understanding of the fabric of reality. The concept of traveling "back" in time implies moving in the opposite direction of the natural progression of events, which conflicts with our understanding of the arrow of time.
Lack of Empirical Evidence: Despite extensive scientific research and technological advancements, no credible empirical evidence or mechanisms have been discovered to support the existence of time travel to the past.
It's important to note that while conventional time travel to the past appears to be impossible based on our current understanding, theories and ideas related to time travel are still actively explored and studied in the realms of physics and theoretical science. However, any potential breakthroughs or new understandings would require significant advancements in our understanding of the fundamental nature of time and the laws of physics.