The Block Universe theory, also known as the Eternalism or Four-Dimensionalism, suggests that the entire spacetime continuum exists as a static, unchanging "block" where past, present, and future all coexist. According to this perspective, there is no privileged "now" or special moment that separates the past from the future.
However, our subjective experience of time seems to indicate the existence of a "now" or a flowing of time. This experience is often referred to as the "phenomenology of time." The question of why we perceive a sense of now or experience the flow of time is still a topic of philosophical and scientific debate.
One potential explanation is related to the concept of the arrow of time and entropy. Entropy is a measure of the disorder or randomness in a system. The second law of thermodynamics states that in an isolated system, entropy tends to increase over time. This increase in entropy gives rise to the arrow of time, as we observe events moving from a state of lower entropy (more ordered) to a state of higher entropy (less ordered).
It has been suggested that our perception of the present moment or the "now" could be linked to the increasing entropy in the universe. Our conscious experience seems to be connected to the evolving patterns of information processing in our brains, which are influenced by the macroscopic processes governed by the arrow of time.
In this view, the "now" emerges as a result of the dynamic interplay between the structure and organization of our brains and the external world. Our perception of time and the sense of a flowing present may be an emergent property of these complex interactions.
However, it is important to note that the nature of time, consciousness, and the relationship between subjective experience and objective reality are still active areas of research and philosophical inquiry. The precise mechanisms through which we experience a sense of now or the flow of time are not yet fully understood and remain subjects of ongoing investigation and debate.