What Is Time? Augustine, Heidegger, and the Physics of the Passing Moment
Augustine of Hippo, in the year 397, wrote one of the most honest sentences in the history of philosophy:
“Quid est ergo tempus? Si nemo ex me quaerat, scio; si quaerenti explicare velim, nescio.”
“What then is time? If no one asks me, I know. If I want to explain it to someone who asks, I do not know.”
He wrote this in the Confessions, a book that is itself a meditation on time, on memory, on the self that persists through the passing of moments.
He is right.
You know what time is in the way you know how to breathe. Without thinking about it, without being able to explain it.
The moment you try to explain it, the thing dissolves.
The present: where is it? By the time you name it, it is gone.
The past: it no longer exists. The future: it does not yet exist.
And yet time is the most real thing there is.
More real than space. More intimate than thought.
You are inside it right now. You cannot get out. You cannot examine it from outside.
This is the problem of time.
I. Augustine. Time as the Soul’s Extension
Augustine’s analysis of time in Book XI of the Confessions is the first great philosophical account of temporal experience.
His starting point: the cosmological question.
“What was God doing before the Creation?”
The naive answer: preparing hell for those who ask such questions. :) (Ahahhahahha!)
Augustine quotes this with gentle irony.
His real answer: the question is malformed.
Before the Creation, there was no time. Time was created with the world. “Before” requires time. There is no before.
“Et nullum tempus, antequam faceres aliquid, fuit, quoniam et ipsum tempus tu fecisti.”
“And no time was, before you made anything, since you yourself made time.”
This is a profound move: time is not the container in which events occur. Time is itself created. It is part of the universe, not the stage on which the universe performs.
Both Augustine and Einstein refuse to treat time as a fixed container that exists independently of everything else. Augustine gets there through theology, Einstein through mathematics. The reasoning is completely different. But the destination has an odd resemblance.
(Whether this counts as anticipation or coincidence is a fair question. I lean toward interesting coincidence.)
The three presents:
Augustine’s most famous contribution to the philosophy of time:
The past does not exist. It is gone. The future does not exist. It has not yet come. The present is a knife-edge. It passes before you can name it.
And yet: we experience all three.
How?
Through the soul.
“Praesens de praeteritis memoria, praesens de praesentibus contuitus, praesens de futuris expectatio.”
“The present of past things is memory, the present of present things is sight, the present of future things is expectation.”
The three modes of time are three modes of the soul’s attention:
Memory: the past held in the present.
Attention: the present grasped in the present.
Expectation: the future anticipated in the present.
All three are present. All three are in the soul.
Time is not out there in the world. It is in here, in the mind that holds past and future in its present attention.
“In te, anime meus, tempora metior.”
“In you, my soul, I measure time.”
This is Augustine’s radical claim: time is psychological.
Not in the sense that it is unreal, but in the sense that temporal experience is constituted by the mind’s activity of holding past, present, and future together.
The distension of the soul:
Augustine uses the word distentio, distension, stretching, to describe the soul’s temporal structure.
The soul is stretched across time. Pulled toward the past by memory, pulled toward the future by expectation, held at the present by attention.
(I have felt this. The soul stretched between what was and what might be, unable to rest in what is. Augustine named it correctly.)
This stretching is not comfortable. It is the source of anxiety, of the restlessness that Augustine describes in the Confessions’ most famous line:
“Inquietum est cor nostrum, donec requiescat in te.”
“Our heart is restless, until it rests in you.”
The restlessness is temporal. The soul stretched across past and future, unable to rest in the present, is the condition of temporal existence.
Rest, the Sabbath, eternity, is the release from distension.
II. Heidegger. Being-Toward-Death
Martin Heidegger’s Being and Time (1927) is the most ambitious philosophical work of the twentieth century.
It’s an attempt to ask, for the first time since the Greeks, the fundamental question:
What does it mean to be?
And his answer: to understand being, you must understand time.
Because being is temporal. Everything that is, is in time.
Heidegger’s fundamental concept: Dasein, being-there, the kind of being that we are.
Dasein is not a subject contemplating an object. It is not a mind inside a body. It is being-in-the-world, already thrown into a situation, already caring about things, already engaged before reflection begins.
Thrownness:
We did not choose to exist. We did not choose our time, our place, our language, our body.
We found ourselves thrown into a situation not of our choosing.
This is Geworfenheit, thrownness.
The facticity of existence: that I am here, now, this, without having chosen any of it.
The temporality of Dasein:
Dasein is always:
Coming from a past it did not choose (thrownness), moving toward a future it cannot avoid (projection), existing in a present shaped by both.
This is the temporal structure of human existence: ecstatic temporality, the “ek-stasis” (standing-outside) of existing always beyond the present moment, always relating to what was and what will be.
Being-toward-death:
Heidegger’s most radical claim:
Death is not an event that happens at the end. Death is a structure of existence. Now.
I am always being-toward-death, always living in the light of my finitude, always existing as the being for whom my existence is an issue.
This is what distinguishes Dasein from a stone or a tree: not consciousness, exactly, but the fact that my being matters to me, that I must take a stand on it, that I cannot be indifferent to whether I exist.
Authentic and inauthentic existence:
Most of the time, we flee from the awareness of finitude.
We lose ourselves in the das Man, the “they,” the anonymous public, doing what one does, thinking what one thinks, living as one lives.
This is inauthenticity, not moral failure, but the everyday flight from the anxiety of genuine selfhood.
(This is the most uncomfortable part of Heidegger for me. Because he is right. Most of what I do on any given day is what “one does.” The genuine choices are rarer than I like to think.)
Authentic existence: confronting death, owning your thrownness, choosing from the possibilities that are genuinely yours, not because they are chosen for you by the anonymous they.
Anxiety:
For Heidegger, the mood that reveals the true structure of existence is Angst, anxiety.
Not fear of a specific thing. Anxiety is anxiety about nothing. About existence itself. About the groundlessness of being. About the fact that I am here without justification or guarantee.
Anxiety strips away the comfortable securities of everyday life and reveals what is always already there: the finite, temporal, groundless structure of human existence.
This is not pathology. It is clarity.
“Der Tod ist die eigenste Möglichkeit des Daseins.”
“Death is the ownmost possibility of Dasein.”
III. The Physics of Time. What Science Says
Philosophy asks: what is time?
Physics answers, partially, strangely, in ways that deepen the mystery rather than resolve it.
Newton’s absolute time:
For Newton, time is absolute, true, and mathematical, flowing equably, without relation to anything external.
It is the background, the container, in which events occur.
The same time passes for everyone, everywhere. There is a universal now.
This is what common sense tells us.
It is wrong.
Special relativity. The relativity of simultaneity:
Einstein showed (1905): simultaneity is relative.
Two events simultaneous in one reference frame are not simultaneous in another.
There is no universal now. The “same moment” means nothing without specifying a reference frame.
Time dilation: moving clocks run slow.
A clock on a fast-moving spaceship ticks more slowly than a clock at rest.
Not as an illusion. Really!
The astronaut who travels at near-light-speed ages more slowly than the person who stays.
Time is not absolute. It is woven into spacetime, a four-dimensional manifold in which time and space are related by the Lorentz transformation.
General relativity. Time curves:
In the presence of mass and energy, spacetime curves. Time itself curves.
Gravitational time dilation: clocks run slower in stronger gravitational fields.
A clock at sea level ticks more slowly than a clock on a mountain. Not by much. But measurably.
GPS satellites must account for this.
Near a black hole: time slows toward the event horizon. At the horizon: time stops, from the perspective of a distant observer.
The block universe:
The most radical implication of relativity:
The block universe, or eternalism, holds that past, present, and future all equally exist.
In special relativity, different observers disagree about which events are simultaneous. There is no preferred “now” that carves the four-dimensional spacetime into past and future.
If there is no preferred now, if “now” is relative to the observer, then the distinction between “things that exist (present)” and “things that no longer exist (past)” is also observer-dependent.
This is not the only interpretation. Presentism holds that only the present is real. The growing block theory holds that the past and present exist but the future does not.
These are live debates in the philosophy of physics.
(I find the block universe unsettling but genuinely hard to argue against. Which is probably how it should feel.)
The arrow of time:
If the laws of physics are time-symmetric, if the equations of QM and GR look the same run forwards and backwards, why does time have a direction?
Why do we remember the past but not the future? Why do broken eggs not reassemble? Why does entropy increase?
The arrow of time is associated with entropy increase. But why entropy was low at the Big Bang, and why this produces our experience of time’s direction, remains genuinely open.
The universe began in an improbable, low-entropy configuration. Everything since has been moving toward greater disorder.
This is the direction we call “future.”
But the deeper question, why that initial condition, cannot be answered from within the physics.
The Planck time:
At \(t_P \approx 5.39 \times 10^{-44}\) seconds, the Planck time, our physics breaks down.
Before the Planck time after the Big Bang: the concept of time may not apply.
Quantum gravity, which we do not have, is needed to describe what “time” means at the Planck scale.
Whether time is continuous or discrete, whether it had a beginning, whether it will have an end, these are questions our physics cannot currently answer.
IV. The Experience of Time. Phenomenology
Between Augustine’s psychological time and physics’ geometrical time, there is a third perspective: the phenomenology of temporal experience.
Husserl’s time-consciousness:
Edmund Husserl, Heidegger’s teacher, analyzed the structure of the “living present” in On the Phenomenology of the Consciousness of Internal Time (1928).
The present moment, for Husserl, is not a knife-edge, an instantaneous now with no duration.
It is a specious present, a small stretch of time that is experienced as simultaneous.
Within this living present:
retention, the just-past, still held in the present experience, and protention, the about-to-come, already anticipated.
When you hear a melody, you hear the notes as a sequence, not as isolated sounds.
You hear them as a melody because the earlier notes are retained while the later notes are heard.
The present moment of hearing contains, within it, the retained past and the anticipated future.
This is why music is possible. This is why speech is possible.
Without retention and protention, each moment would be completely isolated, no connection to what came before, no anticipation of what comes next.
(This is why I cannot listen to music as background noise. The melody requires the whole present. You cannot half-hear it.)
Time-consciousness makes experience coherent.
The phenomenology of boredom:
Heidegger, in his 1929-30 lecture course The Fundamental Concepts of Metaphysics, analyzes boredom as a fundamental mood that reveals the structure of time.
When bored, time slows. Conspicuously.
You become aware of time’s passing precisely because it is not passing.
The structure revealed: time is normally transparent. We live through it without noticing it, absorbed in our activities.
Boredom makes time opaque, suddenly visible, heavy, resistant.
The bored person is held by time, unable to fill it, unable to move through it, exposed to its pure passing.
This is why boredom is so uncomfortable. It exposes the temporality of existence that absorption normally conceals.
The phenomenology of flow:
Mihaly Csikszentmihalyi’s concept of flow, the state of complete absorption in a challenging activity, is the opposite of boredom.
In flow: time disappears. The person is entirely in the present, no past, no future, no awareness of duration.
Athletes, musicians, programmers, writers in the state of deep work, all report the disappearance of time.
Two hours pass in what feels like twenty minutes. Or twenty minutes feel like two hours.
The experience of time’s duration is not measured by the clock. It is constituted by the quality of attention.
Full attention: time disappears. Empty attention: time expands unbearably.
V. Memory. The Past That Lives
Augustine said: the present of past things is memory.
Memory is not a recording. It is a reconstruction.
The reconstructive nature of memory:
Every time you remember something, you reconstruct it, from fragments, from expectations, from your current emotional state, from the story you have been telling about your own past.
The remembered past is not the actual past. It is a present construction of what the past was.
This is not a failure of memory. It is what memory is.
The past, as experienced in memory, is always filtered through the present self doing the remembering.
Proust:
Marcel Proust spent 3,000 pages (I read them,yeah!) exploring this in In Search of Lost Time, the madeleine dipped in tea that suddenly releases a memory not as a record but as a full sensory re-experience, involuntary memory, the past that comes unbidden, more vivid than voluntary recollection, and the narrator’s realization that what he was searching for, lost time, could only be recovered in art, which makes the past permanent by making it the present of the reader. (Wooohoooo, this is Filiz’s longest sentence, a revenge of time spent reading Proust! :))
“The true paradises are the paradises we have lost.”
(3,000 pages on this one idea. And every page earns its place. This is either the most self-indulgent novel ever written or the most honest one. Probably both.)
The physics of memory:
Memory is encoded in synaptic connections, in the physical structure of the brain.
When you remember, neurons fire in patterns that recreate the original pattern.
But: each time you remember, the memory is slightly altered, reconsolidated with new information.
The memory of a memory is not the original experience. It is the memory of the last time you remembered it.
(Which means the memories I am most certain of are probably the most altered. Comforting thought.)
The past, neurologically, is continuously rewritten in the present.
VI. The Future. Expectation and Anxiety
Augustine: the present of future things is expectation.
The future does not exist. And yet we live oriented toward it.
Every action is directed toward a future state. Every plan assumes a future. Every hope, every fear, every intention, all are directed toward what is not yet.
Heidegger’s Entwurf, projection, the way Dasein always throws itself ahead toward possibilities.
We are not beings who have a future. We are beings who are always already projecting ourselves toward a future, who exist in the mode of the not-yet.
The tyranny of the future:
The future that concerns us most is the one we cannot plan for: death.
The awareness of mortality, explicit or implicit, shapes the entire temporal horizon of experience.
Everything is done in the light of finitude.
Every choice involves the other choices that are thereby not made.
Every moment contains the mortality that makes it this moment and not an infinite succession of others.
This is not morbidity. It is the condition of seriousness.
The person who genuinely lives in the awareness of finitude takes their time seriously, knows that this moment is not replaceable, that this conversation, this decision, this experience, will not come again.
The person who lives in denial of finitude can always defer. There will be time later, another chance, a tomorrow that is structurally identical to today.
Death cancels the infinite deferral. It makes the present the only time there is.
VII. The Eternal Present
Against the rushing of time, the Buddhist, the Stoic, the contemplative traditions of many cultures have proposed a different relationship with time:
The eternal present.
Not eternity as infinite duration, time going on forever.
But eternity as the depth of the present, the present moment experienced in its fullness, without the pull of past or future.
Marcus Aurelius:
“Confine yourself to the present.”
Not as a counsel of forgetfulness, but as a recognition that the past and future are not available to us. Only the present is real. Only the present can be inhabited.
The mind that is always elsewhere, in the regretted past, in the anxious future, is never where it is.
The physics of the present:
In special relativity, the light cone of an event divides spacetime into three regions: the past (what could have caused this event), the future (what this event could cause), and the spacelike-separated region, a vast set of events that cannot be causally connected to this event at all.
The “absolute present” in this sense is not a thin slice. It is enormous.
The contemplative idea of a deep, full present is philosophically interesting. But it does not map onto the physics in any tidy way.
The poetry is tempting. The physics does not cooperate.
VIII. Time and Language
Wittgenstein noted: the grammar of our language generates philosophical puzzles about time.
“Time passes,” but what is the subject? What is doing the passing?
“The same moment,” what makes moments the same or different?
“Now,” the most indexical word in language, pointing to the present, cannot be given a description that is not itself indexical.
Every attempt to describe “now” uses another word that refers to now.
The grammar of temporal language is not a description of time. It is a form of life, a set of practices for coordinating human activity in time.
When we ask “what is time?” we may be asking: what is the grammar of temporal language?
And the answer may be: there is no deeper answer. The grammar is what it is. The practices are what they are.
Time is what we do with it!
IX. What We Don’t Know
After Augustine, after Heidegger, after Einstein, after quantum mechanics, what do we know about time?
We know:
Time dilates with velocity and gravity.
The arrow of time is associated with entropy increase, though why entropy was low at the Big Bang remains unexplained.
Time had a beginning, the Big Bang.
Below the Planck time, time has no meaning.
We don’t know:
Whether time flows or is static.
Whether the present is real or relative.
Whether time is continuous or discrete.
Whether time had a beginning in any absolute sense.
What happened before the Big Bang, or whether “before” applies.
Why the universe began in a low-entropy state, which is the real origin of the arrow of time.
Whether time is fundamental or emergent.
The deepest mystery:
Why does time seem to flow?
In the block universe, all moments equally exist. Nothing moves. Nothing passes. The universe is a static four-dimensional structure.
And yet: you experience time as flowing.
The present feels different from the past. The future feels open in a way the past does not.
Why?
This question, the question of why we experience time as flowing in a world where physics suggests nothing flows, is the hardest question in the philosophy of time.
It connects physics to consciousness. It connects the structure of the world to the structure of experience.
It has no agreed answer.
X. Living in Time
All of this philosophy, all of this physics, and time remains what it was before any of it:
The medium of your life. The stuff you are made of. The dimension in which everything happens, everything you remember, everything you anticipate, everything you are doing right now.
Augustine’s restless heart. Heidegger’s being-toward-death. Einstein’s dilating clocks. Proust’s involuntary memory. The Stoic’s present moment.
All of these are attempts to understand the same thing:
What it is to be a being who exists in time, who is constituted by past, oriented toward future, and always already in the present that passes before it can be held.
The answer is not available. The question is indispensable.
“Si nemo ex me quaerat, scio.”
If no one asks me, I know.
I know it right now, this moment, this passing, this movement from what was to what will be through the knife-edge of what is.
I know it in the way I know how to breathe.
And when I try to explain it, I do not know.
Further reading:
Augustine. Confessions (397). (trans. Henry Chadwick, Oxford World’s Classics). Book XI for the philosophy of time.
Heidegger. Being and Time (1927). (trans. Macquarrie & Robinson, or Stambaugh). Division Two for temporality and death.
Husserl. On the Phenomenology of the Consciousness of Internal Time (1928). (trans. Brough, Kluwer).
McTaggart. “The Unreality of Time” (1908). Mind 17, 457. The A-series / B-series distinction; essential.
Price. Time’s Arrow and Archimedes’ Point (1996). Oxford University Press.
Barbour. The End of Time (1999). Oxford University Press.
Rovelli. The Order of Time (2018).
Proust. In Search of Lost Time :)) (Filizko suffered, now it is your turn! Ahahah!) :)) (trans. Moncrieff & Kilmartin).
Penrose. The Road to Reality (2004). Chapters 27-28 for time asymmetry.
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