“Time by itself does not exist. It must not be claimed that anyone can sense time apart from the movement of things.” ~ Roman philosopher Lucretius
“What is time? If nobody asks me, I know; but if I were desirous to explain it to one that should ask me, plainly I know not.” ~ Augustine of Hippo
Classical physics regarded time in the way we are familiar: a vector of past, present, and future; subject to subjective interpretation, but ultimately an objective metric.
“Absolute, true and mathematical time, of itself, and from its own nature, flows equably without regard to anything external, and by another name is called duration.” ~ Isaac Newton
Near the end of the 19th century, Austrian physicist Ludwig Boltzmann assaulted the temporal vector, arguing that time had no built-in arrow; but that its application in space gave time meaning, as entropy was irreversible.
“The only reason for time is so that everything doesn’t happen at once.” ~ Albert Einstein
Temporality lost its absoluteness with special relativity, which rendered time as relative to a frame of reference. 2 events may occur simultaneously or sequentially, depending upon point of view.
“The past, present and future are only illusions, even if stubborn ones.” ~ Albert Einstein
Under special relativity, causality is a point of view. The implication is that time, as a matter of perspective, is only an apperception.
Equivalently, time has no meaning in the quantum realm, nor does causality. The world simply incessantly is. Existence itself as an emergent phenomenon: spacetime itself coming into being. Continuity is a perspective, not a phenomenon.
General relativity posits that gravity warps spacetime: not just space, and not just time. Under general relativity, time stops upon entry into a black hole, and space ceases to exist. A singularity of infinite mass collapses space upon itself and squeezes time to a standstill.
Whereas space comprises equivalent dimensions that must be unified for manifestation, time stands alone. Relativity’s twining of spacetime goes only to gravity’s effect: inferring elasticity in time as a geometric fluid medium.
Heisenberg’s uncertainty principle posits an inherently nondeterministic reality through time. Under uncertainty, space and time are in a flux: where and when are probabilistic.
“Everything in the future is a wave. Everything in the past is a particle.” ~ English physicist William Lawrence Bragg
The only particle of time is the present moment, when wavelike interconnections in space have crystallized. Nonlocal simultaneity simply is; its recognition merely a perception by a mind insisting upon continuity.
“Nothing in known physics corresponds to the passage of time.” ~ English physicist Paul Davies
Between past and future, the present is an instantaneous confluence; the only moment of existence. Despite having no accounting for its passage, physics depends entirely upon time.
“You could make different choices of what you mean by time and get any laws of physics you like.” ~ American theoretical physicist Andreas Albrecht
As the potentate of entropy, gravity plays with time. There is more to it than that. Spacetime and gravity define each other.
“Many physicists believe that on the very smallest scale of size and duration, space and time might lose their separate identities.” ~ Paul Davies
At the quantum level, gravity is assumed to exist in granular form. Similarly, time is simply taken for granted as having tiny steps. If the measures become too tiny, time simply stops. This is the Zeno effect.
“The quantum Zeno effect is the inhibition of transitions between quantum states by frequent measurements of the state. The inhibition arises because the measurement causes a collapse of the wave function. If the time between measurements is short enough, the wave function collapses back to the initial state.” ~ American physicist Wayne Itano et al
Zeno of Elea was a 5th century BCE Greek philosopher and mathematician who had an inordinate fondness for paradoxes. Aristotle credited Zeno with inventing dialectic: logic based upon the interaction of juxtaposed ideas.
The Zeno effect is maintaining stasis in a quantum system via continuous observation. Time evolution in a quantum system is completely suppressed simply by continuously observing it.
The term Zeno effect comes from Zeno’s arrow paradox, which states that because an arrow in flight is not seen to move at any instant, the arrow cannot possibly be moving at all. It is a proposition based on the infinitesimals upon which calculus is built.
The Zeno effect is also called the Turing paradox, from Alan Turing’s 1954 observation that continuously measuring a system increases to infinity the probability that the system will be in the same state from one observation to the next: “that is, that continual observations will prevent motion.”
The Zeno effect has been repeatedly verified in quantum and atomic systems. It remains inexplicable.
“Until a trustworthy algorithm is developed to explain the Zeno effect, the completeness of quantum theory must remain in doubt.” ~ Indian physicists Baidyanath Misra & George Sudarshan
Awareness makes time stand still. Time’s progression is a matter of inattention.
“The quantum Zeno effect is real; a watched quantum pot never boils.” ~ English astrophysicist John Gribbin
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The Zeno effect applies to a localized quantum system. The classical effect of time’s arrow takes hold because quantum systems are entangled in a larger-scale multisystem. This entanglement induces delocalization and the classical irreversibility of time: an anti-Zeno effect. Classical chaotic dynamics exist because awareness cannot cover the world at large.
Quantum events that shape moment-by-moment actuality occur in the shortest time (Planck time). At that scale, time has no meaning. This is in stark contrast to the tale time will tell over the eons of cosmic expanse, from what supposedly started as a singular quantum, then spread through time as a gyral web.
The singular force of time in a timescape is equivalent to all the forces influencing landscape at every scale. But whereas empty space is uniform, time has different characters at the extreme scales of existence.
“Our perception of time profoundly influences our perception of change. A drastic change at one scale may appear trivial at another.” ~ American evolutionary biologist Stephen Jay Gould
Ultimately, for all its abstract foibles, physics treats time as the pesky vector that it is for all concerned, regardless of scale or scope. The bottom line is that time is as slippery as it seems: an illusion that can’t be grasped however strongly felt. That, at least, is a unified theory of time.
“Time is free, but it’s priceless. You can’t own it, but you can use it. You can’t keep it, but you can spend it. Once you’ve lost it you can never get it back.” ~ American businessman and writer Harvey MacKay