Evolving Block Universe Research Articles

Physical Time and Human Time

This paper is a comment on both Bunamano and Rovelli (Bridging the neuroscience and physics of time arXiv:2110.01976. (2022)) and Gruber et al. (in Front. Psychol. Hypothesis Theory, 2022) and which discuss the relation between physical time and human time. I claim here, contrary to many views discussed there, that there is no foundational conflict between the way physics views the passage of time and the way the mind/brain perceives it. The problem rather resides in a number of misconceptions leading either to the representation of spacetime as a timeless Block Universe, or at least that physically relevant universe models cannot have preferred spatial sections. The physical expanding universe can be claimed to be an Evolving Block Universe with a time-dependent future boundary, representing the dynamic nature of the way spacetime develops as matter curves spacetime and spacetime tells matter how to move. This context establishes a global direction of time that determines the various local arrows of time. Furthermore time passes when quantum wave function collapse takes place to an eigenstate; during this process, information is lost. The mind/brain acts as an imperfect clock, which coarse-grains the physical passage of time along a world line to determine the experienced passage of time, because neural processes take time to occur. This happens in a contextual way, so experienced time is not linearly related to physical time in general. Finally I point out that the Universe is never infinitely old: its future endpoint always lies infinitely faraway in the future.

Emergence of Time

Microphysical laws are time reversible, but macrophysics, chemistry and biology are not. This chapter explores how this asymmetry (a classic example of a broken symmetry) arises due to the cosmological context, where a non-local Direction of Time is imposed by the expansion of the universe. This situation is best represented by an Evolving Block Universe, where local arrows of time (thermodynamic, electrodynamic, gravitational, wave, quantum, biological) emerge in concordance with the Direction of Time because a global Past Condition results in the Second Law of Thermodynamics pointing to the future. At the quantum level, the indefinite future changes to the definite past due to quantum wave function collapse events.

Falsification Experiments for Spacetime Theories from the Neurological Sciences

One difficulty with spacetime theories is the absence of falsifications tests. Because the observer is part of quantum mechanics (QM) and therefore an obligatory part of cosmological theories that incorporate QM, the neurological sciences have a legitimate role. We examined six different QM based cosmological theories. They make implications about various aspects of the flow of time (FOT)--the past/present/future experience including subjective dynamism). First, a distinction is made between the FOT and the physical passage of time (POT), the occurrence of a new physical event at the periphery of an expanding universe. Four theories suggesting a real POT are the Evolving Block Universe, the Spacetime Dynamics Theory, Causal Set Cosmology; and Muller’s cosmology. However, they retain the past/present components of the Block Universe and imply that the upper level FOT (the experience that the ‘present’ is unique) is illusory. A falsification experiment is proposed utilizing Hartle’s proposed Information and Gathering and Utilizing Systems (IGUSs), which have different experiences of the ‘present’. A virtual reality IGUS which can experientially navigate between past and present is suggested. It could confirm their implication that the experience of past/present events is not unique (i.e., it is a variable cognition). Barbour’s timeless theory involves relative configuration spaces which contain enough information to provide an illusory dynamic scene. That experience of dynamism within that scene is said to be an illusion. A second falsification experiment is proposed to remove dynamism suggesting it is an irrelevant experience. It involves intermittent stimulation of the newly discovered consciousness center (the claustrum) to create brief intervals of unconsciousness. Doing this precludes the recently discovered ‘happening’ percept which can account for the entirely of dynamism (the lower level FOT). The negative implication for Temporal Naturalism in the Cosmological Natural Selection theory is briefly discussed.

Ricci time in the Lemaître–Tolman model and the block universe

It is common to think of our universe according to the “block universe” concept, which says that spacetime consists of many “stacked” three-surfaces, labelled by some kind of proper time, $$\tau $$ . Standard ideas do not distinguish past and future, but Ellis’ “evolving block universe” tries to make a fundamental distinction. One proposal for this proper time is the proper time measured along the timelike Ricci eigenlines, starting from the big bang. This work investigates the shape of the “Ricci time” surfaces relative to the the null surfaces. We use the Lemaître–Tolman metric as our inhomogeneous spacetime model, and we find the necessary and sufficient conditions for these $$\{\tau = $$ constant $$\}$$ surfaces, $$S(\tau )$$ , to be spacelike or timelike. Furthermore, we look at the effect of strong gravity domains by determining the location of timelike S regions relative to apparent horizons. We find that constant Ricci time surfaces are always spacelike near the big bang, while at late times (near the crunch or the extreme far future), they are only timelike under special circumstances. At intermediate times, timelike S regions are common unless the variation of the bang time is restricted. The regions where these surfaces become timelike are often adjacent to apparent horizons, but always outside them, and in particular timelike S regions do not occur inside the horizons of black-hole-like models.

The evolving block universe and the meshing together of times.

It has been proposed that spacetime should be regarded as an evolving block universe, bounded to the future by the present time, which continually extends to the future. This future boundary is defined at each time by measuring proper time along Ricci eigenlines from the start of the universe. A key point, then, is that physical reality can be represented at many different scales: hence, the passage of time may be seen as different at different scales, with quantum gravity determining the evolution of spacetime itself at the Planck scale, but quantum field theory and classical physics determining the evolution of events within spacetime at larger scales. The fundamental issue then arises as to how the effective times at different scales mesh together, leading to the concepts of global and local times.

The arrow of time and the nature of spacetime

This paper extends the work of a previous paper (Ellis, 2013) on the flow of time, to consider the origin of the arrow of time. It proposes that a ‘past condition’ cascades down from cosmological to micro scales, being realized in many microstructures and setting the arrow of time at the quantum level by top-down causation. This physics arrow of time then propagates up, through underlying emergence of higher level structures, to geology, astronomy, engineering, and biology. The appropriate spacetime picture to view all this is an Evolving Block Universe ‘EBU’, that recognizes the way the present is different from both the past and the future. This essential difference is the ultimate reason the arrow of time has to be the way it is.

Time and Spacetime: The Crystallizing Block Universe

The nature of the future is completely different from the nature of the past. When quantum effects are significant, the future shows all the signs of quantum weirdness, including duality, uncertainty, and entanglement. With the passage of time, after the time-irreversible process of state-vector reduction has taken place, the past emerges, with the previous quantum uncertainty replaced by the classical certainty of definite particle identities and states. The present time is where this transition largely takes place, but the process does not take place uniformly: Evidence from delayed choice and related experiments shows that isolated patches of quantum indeterminacy remain, and that their transition from probability to certainty only takes place later. Thus, when quantum effects are significant, the picture of a classical Evolving Block Universe (`EBU') cedes place to one of a Crystallizing Block Universe (`CBU'), which reflects this quantum transition from indeterminacy to certainty, while nevertheless resembling the EBU on large enough scales.

Physics in the real universe: time and spacetime

The Block Universe idea, representing spacetime as a fixed whole, suggests the flow of time is an illusion: the entire universe just is, with no special meaning attached to the present time. This view is however based on time-reversible microphysical laws and does not represent macro-physical behaviour and the development of emergent complex systems, including life, which do indeed exist in the real universe. When these are taken into account, the unchanging block universe view of spacetime is best replaced by an evolving block universe which extends as time evolves, with the potential of the future continually becoming the certainty of the past. However this time evolution is not related to any preferred surfaces in spacetime; rather it is associated with the evolution of proper time along families of world lines