If 3D Time and 3D Space were interchangeable, we have a unified theory of science which is easier to comprehend than the complex string theory. The recent work on the possibility of multiverse rather than universe brings us closer to understanding the cosmos and the closer we get to understanding cosmos, the closer we get to understanding Time. The Big Bang mystery of expansion and contraction has been challenged by a new theory which uses dark matter to explain why the big bang may not contract but expand forever.
On one side this confirms the second law of thermodynamics (increasing entropy) but on the other side it opens up another debate regarding the symmetry of time. Physical processes at the microscopic level are believed to be time symmetric as laws of physics remain true even if the direction of time is reversed. However, at a macroscopic level, there is an arrow (direction) of time that exhibits such time-asymmetry. Time takes the direction of entropy, moving in the direction from low entropy to high entropy. Increasing entropy is the reason why we can’t convert a broken egg back into an egg or why we can’t stop aging or decaying. Arrow of time is the reason future and past is distinguishable.
On one side the arrow of time explains the life that we live in this universe and on the other side if the second law of thermodynamics was a rule, life as we know it won’t be possible. This contradiction works against a unified theory of science as it fails to explain why low entropy can co-exist in a high entropy environment like the expanding universe. In other words, how can order exist in a world that is meant to be disordered?
The Boltzmann's brain was hypothesized as a self-aware entity which arises due to random fluctuations out of a state of chaos. The idea is named for the physicist Ludwig Boltzmann (1844–1906), who advanced an idea that the known universe (order) arose as a random fluctuation. Boltzmann proposed that even in a near-equilibrium state, there will be stochastic fluctuations in the level of entropy resulting in only small amounts of organization. The data disproved this as the level of an order was much higher than being due to a random fluctuation. Above this the fact that we are close to finding more habitable planets like earth challenges that life is indeed a rare fluctuation.
Sean Carroll retweaked Boltzmann working and explains that though fluctuations in a high entropy state could explain the reason for life, living in a fluctuation (an extremely rare event) is not enough to explain the visible order. There was a large proof of habitable life in thermal equilibrium (which is not conducive to live).
Cosmos clustered and formed galaxies and states of low entropies more frequently than expected. There were more than a few fluctuations in nature. There were more than a few low entropy states in a large entropy environment. Sean suggests that the answer might lie in events before the big bang. Assuming there was nothing before the big bang was not convincing enough. There was a need for a better theory than general relativity. Sean explains how high entropy systems continually create low entropy big bangs. This was the reason we were a part of a multiverse and not a universe. These conditions create lack of thermal equilibrium and the reason for life. Multiverse also explains why time is symmetric even if live through one arrow of time.
Though Sean is unsure regarding his multiverse, time fractals suggest a symmetric time and confirm Sean’s view. The symmetry of time means there is a moment when time symmetry starts and time when the symmetry completes before starting again. A low entropy moment is when a time cycle starts and highest entropy is when a cycle peaks. The two aspects of time, the repetitive and change time also explains why though time is ordered it also brings relentless change. Putting simply time is the reason why we live in a measurable and ordered world with an unpredictable future. The reason history does not repeat but rhymes are because evolution goes on with changing time. Repetitive time is the reason the entropy starts again and why despite high entropy in one universe we have another low entropy beginning of a new universe in a similar time.
Low to high entropy can also be seen as efficiency to inefficiency. More entropy is the reason for more inefficiency than efficiency in nature. We can also describe entropy process as a shift from homogeneous to heterogeneous, normal curve to fat tails, mean reversion to divergence. High entropy seems to be a natural feature of everything around us. Entropy is the reason life is full of extremes, inefficient extremes. Because time is symmetrical in all directions and is fractalled we can experience coexistence of high and low entropy in a similar time.
The universe is one arrow system. But since time is symmetrical and 3D in nature time can have various arrows of time in all directions. This is the reason why multiverse is a reality. Our paper on Temporal Changes suggested changes in time duration being the reason for inefficiency in markets (more than a few fluctuations). Using cosmic Time to illustrate a similar inefficiency would prove that 3D space is an extension of 3D Time. And life is not a rare fluctuation it is an order caused by the vibrating string called Time.