Stephen Hawking, in one of his most fascinating famous works , asserted that the psychological arrow of time, that is, the perceptual awareness of the direction of the “flow” of temporal events, is necessarily oriented with direction concordant with that of its thermodynamic counterpart.
He bases his demonstration on the fact that any information storage system (e.g., the RAM of a computer or an animal’s brain) must expend a certain amount of energy to achieve its predetermined purpose. Following the second principle of thermodynamics, the elements deputed to “store” data, once the process is completed, degrade some of this energy by dissipating the waste of their work in the form of heat.
This condition, according to Hawking, represents the natural element that governs awareness of the directionality of time; however, as the author himself admits, our knowledge about the workings of the human brain is still too paltry to say with certainty that it functions in the same way as a semiconductor memory cell, even though it is reasonable to assume that every biological structure, from the most basic single-celled microorganism to humans, is subject to the same laws that govern the universe. Even without in-depth knowledge, according to what is stated in footnote 1, it is possible to see that nature constantly evolves toward privileged directions that lead inexorably toward equilibrium, understood as thermal death. Still, the phenomenon of life seems not to respect this condition!
In , Nobel laureate Erwin Schrodinger states that living beings exhibit behavior opposite to that sanctioned by the second principle, in that they are born and live while internally maintaining an extremely high level of order and organization. (To get an idea, think that a young man’s brain contains about a hundred billion neural cells interconnected by a network in which the single node may contain as many as ten thousand (or two hundred thousand in the case of Purkinje cells) interconnections !)
Schrodinger, as a good theoretical physicist, justifies the strangeness of this phenomenon by advancing the hypothesis that living beings, while being forced to degrade energy like any other thermal machine, “absorb” neg-entropy (i.e., entropy with a minus sign) from the environment to compensate for the increase they would otherwise inevitably experience. In  on p. 123, he says, ” …Less paradoxically, it may be said that the essential in metabolism is that the organism should succeed in getting rid of all the entropy it cannot but produce in the course of life. “, i.e., simply put, the primary purpose of the causes of life is certainly not to obey the second principle of thermodynamics blindly, but rather to counteract it by all necessary means. The vital essence of a being springs from the continuous relationship clash with the laws of nature! In light of this simple theory, I believe Hawking’s statement is not entirely correct, and in this short article, I will try to explain my position.
Admitting that the biochemical processes regulating brain metabolism can ” reveal” the natural direction of time, one must also accept that the slightest nerve activity is sufficient to ensure constant contact with the reality of the universe. In a sense, following the teachings of Immanuel Kant , it can be said that time, whatever it is, always precedes experience. Therefore, it must be intuited a priori and without the intervention of sensory perception. However, if this were the case, consciousness would not be necessary since the standard cellular work of the brain (which can disregard all five senses and manifest even in a person in a coma) would suffice to give awareness of the succession of individual temporal instants.
However, analyzing the issue from the point of view not of causes but of effects, the processing and storing of information (which is the result of brain activity) leads an infant from a level of total immaturity to an adult being increasingly aware of self and the external environment, thus, in the final analysis, it can be said that the “shift” along the axis of time (life) guides reason and consciousness toward a direction that is the result not of the normal natural tendency toward disorder, but rather, as Schrodinger puts it, of the continuous acquisition of neg-entropy.
I believe that neural activity of an electrochemical nature contributes to the construction of a mental image of time that is opposite to that of the thermodynamic arrow and that sensory perceptions force the brain to “work against the current.” In this way, the succession of individual samples of tactile, optical, and acoustic signals guides the evolution of knowledge in the same direction that ensures the constant increase of entropy, thus forcing consciousness to follow the information content of brain processing, which acquires rational coherence only if it evolves in concordance with any other natural phenomenon.
Man interfaces with nature, observes it, and makes it a privileged environment. Still, the appearance of the temporal motion he obtains from it is not the logical consequence of his belonging to the same reality (in a conditional sense) but the result of a process of adaptation. Although this may seem unscientific, I believe that the concept of time, as the laws of physics show it, is entirely foreign to the human mind, and this is perhaps the reason why an adequate description of it still cannot be given.
Probably out of intellectual poverty, I argue that it is much more honest to say that all mathematical results in the physical field depend on a real-value variable that can be called time for experimental and consistency reasons. Still, there is no rational justification for its indiscriminate use. For example, when in mathematics we plot Cartesian diagrams of a function of time y = f(t), we provide a picture of the time evolution of a quantity (y) by letting it be understood that it is possible to assign any t value belonging to the domain of f thus obtaining the result of the operation f(t).
When applied in the physical field, this procedure loses all meaning because the calculation f(t) can never correspond to reality except when t takes on the desired value. According to Laplace’s mechanistic view, knowledge of laws and initial conditions is sufficient to predict the future. However, he took refuge in the calculus of probabilities when problems became too complex to be addressed. (It is unnecessary to refer to systems with some Avogadro number of particles: the three-body problem is already a prime example of the difficulties in solving using a deterministic approach. If, in addition to solving the system of differential equations, one associates the total inability to know the initial and boundary conditions, the obstacle becomes truly insurmountable).
Entropy is the result of this approach and, in a sense, defines the concept of time without any reference to the real variable t. It does not matter when and how it varies since what is certain is that in the face of a ΔS change, the human mind always perceives what is usually called time.
Consequently, taking into account that the ultimate goal of life is based on organization and order in the brain and that this result arises from the acquisition of neg-entropy (-ΔS) it can be deduced that human time can never be represented by a mathematical variable (which due to its scalar nature contains no information about the direction of changes and is perfectly symmetrical) and consciousness of it can only manifest itself in a living being in the face of a change in perceptual sequences, which produce a corresponding increase in synaptic connections between neurons and thus directly increase the complexity of the natural neural network.
In , Kant, in his transcendental exposition of the concept of time, states, ” …the concept of change, and with it, the concept of movement, is possible only utilizing the representation of time; that if this representation were not (internal) intuition a priori, no concept, whatever, could make intelligible the possibility of change, that is, of the union in the same object of contradictory opposite predicates.
Only in time, one after the other, can two contradictory opposite determinations meet together in one thing. Thus, our concept of time explains the possibility of as much synthetic a priori knowledge as the general theory of motion offers us, which is not unproductive. “.
At this point, I wonder if Kant, undoubtedly aware of Newton’s work, was not swayed by the fact that in every mechanical equation, there appears implicitly or explicitly the variable t, without which no clockwise law of motion can be defined, and, based on this observation, decreed the pure and a priori existence of an autonomous, absolute (at least until the advent of Einstein’s general relativity) and immutable essence called time.
I do not believe there can be any acceptable justification for that reality, not even in the wise words of Kant. I can only take note, along with Schrodinger, that life, regardless of any physical laws, feeds on signifiers and meanings and that the thermodynamic arrow of time invests it entirely in the face without, however, affecting its evolution. It may be that if one day we arrive at the GTU (Grand Unified Theory), every constant and every variable used will acquire a precise meaning that the human mind can understand and accept without inevitably having to leave behind a long path strewn with ditches and chasms, but until then it is far better not to hazard hypotheses that only in the abstraction of pure mathematics can find an appropriate logical place.
But how can we justify the temporal advancement we all experience every day? Just above, I said, perhaps too arrogantly, that it is the adaptation to reality that determines this particular awareness and that, therefore, again going back to Kant, it arises from the implicit analysis of a proper a posteriori analytical judgment (precisely the opposite of what was stated in ) and, to support this thesis, I referred to the continuous elaborative process that the brain (and therefore the mind) operates. It aims to attain ever finer and more articulated organization, and to do so, it constantly “fights” a battle against the universe, which, on the contrary, races toward thermal equilibrium.
Thus, there are two relative motions, both in the same direction but with opposite directions: man travels on a reference system that, without angering cosmologists, can be considered in motion toward a big bang, while the universe, according to Friedman’s theories, tends, as its ultimate goal, toward a probable big-crunch.
Hawking himself in  raises the question of why the thermodynamic arrow of time coincides in direction with that which marks the expansion of the universe and states based on the anthropic principle that: ” …The conditions in the contraction phase would not be suitable for the existence of intelligent beings capable of asking the question: why is the disorder growing in the same direction as the time in which the universe is expanding ? “in reality, even assuming that life could not have manifested itself if the speed of expansion were opposite to the current speed of expansion (collapse), one cannot fail to take into account that intelligent observation (as the essence of life itself) is precisely the result of a hypothetical reversal of the axis of time aiming at order and not of a natural tendency to increase entropy.
All cells must indeed obey the laws of thermodynamics; their metabolism is perfectly analogous to the result achieved by the power grid of an electronic circuit. Still, it is also true that they constantly need an almost unlimited source (it would not be inappropriate to speak of a reservoir) of neg-entropy, which could not occur in a contracting universe. In this sense, I fully agree with Hawking’s view while admitting, at the same time, that if the real psychological arrow of time points in the opposite direction to the thermodynamic arrow of time (my position), it must also be opposite to the cosmological arrow of time. Therefore, as I said before, the motion of time related to information acquisition and processing must occur as if one were moving toward the Big Bang.
Of course, without information sources, the brain loses the perceptual capacity for time and can no longer agree even approximately with a clock. A classic example of this is sleep: I do not believe any person can estimate its duration even if his or her nervous system has remained partially active (especially in REM phases).
Should it be sufficient to “perceive” the thermodynamic arrow of time to get a sense of the succession of events, maintaining contact with the universe even during phases of a partial or total loss of consciousness should also be possible. By this, I do not mean that a grown man, upon awakening, might doubt that he is in the future compared to the time of falling asleep will be more than certain that he has spent a short period of his life asleep-but this is not a consequence of his metabolism but, I repeat, of the habit of living in a reality that obeys the second principle of thermodynamics.
On the other hand, as Julian Barbour points out (see footnote 3), the brain is a machine based essentially on a serial type of processing (only regarding the same data stream), and, as a result, individual “mental frames” follow one another in an orderly series that mirrors natural movements. In addition, perceptual channels, like the eyes, have limited temporal resolving power; if, for example, a person is shown two images in rapid succession, there is a limit below the minimum gap below which he or she is no longer able to distinguish which of the two figures appeared first. In such situations, the brain interprets the result by operating a kind of effective time suppression!
From a physical point of view, the two frames are temporally spaced, and making them visible is undoubtedly in accord with the second principle, but appearance (and thus perception) violates it without any qualms. Neurons engaged in “capturing” spatial and chromatic information also feed on energy and produce waste materials, but the result does not change in any way. Is it then possible to say that metabolism is enough to justify the directionality of time?
Suppose this were so, regardless of resolving ability. In that case, one should always be sure that one image is later or earlier than another, even without grasping the message conveyed. Furthermore, in , the two authors report on recent neuroscientific research that has unveiled important new functional realities of the cerebellum: ” …In 1989, Richard B. Ivry and Steven W. Keele of the University of Oregon noted that patients with cerebellar damage could not accurately quantify the duration of a particular sound, or the time elapsed between two nearby sounds… “.
In the same article, scientists set forth the most correct (and modern) viewpoint regarding this organ, and the biggest surprise arises from the fact that all studies confirm the cerebellum’s significant active participation in perceptual operations. According to what I have previously expounded, spatiotemporal events are finely analyzed and processed by the brain (with the significant help of the cerebellum), and if these, for pathological reasons, fail to do their job correctly, the interpretation of changes in the time domain (but not only) is severely impaired.
Once again, the trophic activity of neurons, as computational elements, loses that informational priority (concerning the conscious perception of time) that belongs solely and exclusively to the processing of incoming information.
By what has been stated, I am also convinced that an infant has no inherent ability to evaluate the difference that exists between the past and the future, and this is not because his intellectual level is still too limited (at most, this could be an obstacle to comprehension and verbal expression), but because his experience is minimal. Beginning from his first moment of extra-uterine life, the child begins to observe the evolution of phenomena, especially those that affect him personally; for example, he slowly realizes that the sensation of hunger exists before he has sucked milk, soon after he reaches a satisfactory level of contentment and stops crying. His perception of time begins to model itself based on the natural order in the physiological stimuli category. It slowly develops by extending “the known universe” to the mi(-a)crocosm around him.
However, in saying these things, I would not want my position to appear as an implicit tendency to spiritualism; I believe that the mind, that is, the most manifest and extraordinary effect of life, is the (mysterious) result of brain activity, which obeys the same laws that govern the behavior of matter. Yet, unlike a mountain, a star, or a planet, a man develops his abilities with a kind of intentionality independent of the initial and boundary conditions.
In contrast, although described by rigorous mathematical relations, the universe cannot travel any trajectory in space-time unless the initial conditions are first accurately defined. Then again, this should come as no great surprise because, in infinitesimal calculus, the solution of a differential equation acquires unitarity only in the context of a so-called Cauchy problem.
It is clear then that man cannot be “mathematically modeled” in this way because otherwise, one would risk thinking of it as a mere automaton programmed to achieve certain ends, inevitably falling under the weight of the criticism raised by a great many philosophers (including John Searle of the University of California) against an algorithmic view of the mind (the Churchland thesis); consequently, if one admits free will in a broad sense (which destroys any possibility of thinking of brain activity as a computer program) one must also admit that the concept of law itself (in its most formal sense) loses all generality in this context.
Thus, there is a satisfactory answer: what is time? I honestly don’t know, but I believe that a critical role in defining this quantity is played by the information itself, which, along with mass, energy, and electric charge, is an essential ingredient for life and the existence of the entire universe. Considering that the definition of information data implicitly contains the concept of sequence, it seems pretty natural to me to associate the variable t precisely with the exploration of the sequence above. In summary, we can say that human beings perceive the existence of information and, thanks to the sensory apparatus, manage to “take possession” of it; in performing this operation (even involuntarily), the result of sequential/parallel brain work, which, physically and mathematically speaking, we can call time, spontaneously comes out.
By coincidences still completely unknown, there is an experimental relationship between the variation of imperceptible physical quantities and the evolving continuum in which we all have to live. Perhaps one day, this mystery will also be revealed!
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