The Cruel Arithmetic of Time
The Philosophy of Temporal Acceleration
This piece opens a series of personal reflections called “Midlife Mediations” on turning 50 next year. It explores how we inhabit time, create meaning, and understand what it means to “arrive” in life. Future articles will examine our fragmented attention, the urgency of now, and the practice of imperfection in our quest for temporal depth.
At nearly 50, I confront a mathematical truth that cuts deeper than mere numbers: When I was 5, a year represented 20% of my existence. At nearly 50, that same year comprises merely 2% of my lived experience—a ten-fold difference in proportional significance that may help explain why time seems to accelerate.
Or, to put it into the simple words the American radio and television writer Andy Rooney used:
I’ve learned...That life is like a roll of toilet paper.
The closer it gets to the end, the faster it goes.
However, neuroscience reveals more than mathematics alone, confirming the subjective acceleration. Our brains evolved for survival rather than savoring, and neuroscientist David Eagleman’s research—particularly his 2009 study on the “oddball effect” demonstrating how novel stimuli expand subjective time—shows that our perception of time’s passage depends mainly on how memory formation works. Childhood summers felt endless, not just because they represented larger life proportions, but because every experience was novel, demanding full cognitive engagement and creating rich, detailed recollections. These novel experiences trigger dopamine release, enhancing memory encoding, while familiar routines compress into efficient neural shortcuts.
This neural adaptation explains why decades that once stretched like eternities in childhood now flash by—we’re not just living through smaller proportions of our lives, but encoding dramatically fewer distinctive moments worth remembering.
The Ancient Greeks and the Architecture of Time
Before neuroscientists mapped temporal perception mechanics, the ancient Greeks recognized the difference between chronological time (chronos) and subjective time (kairos). Kairos carried the meaning of “the right or critical moment,” with etymological roots in archery—not just when an arrow may be fired with sufficient force to penetrate a target, but the precise moment when all conditions—wind, distance, target position—aligned perfectly.
In mythology, Kairos is depicted as a young, fleet-footed god of the “fleeting moment,” representing the precise moment when circumstances align for decisive action. He has to be grasped by the tuft of hair on his forehead; otherwise, the moment will slip away and can never be recaptured.
This ancient distinction illuminates a modern paradox: as our lives become increasingly dominated by chronos—schedules, deadlines, digital timestamps—our capacity to recognize and inhabit kairos moments diminishes. Chronos measures duration; kairos creates significance. This Greek insight parallels concepts found across cultures: Indigenous circular time understanding, where past, present, and future interconnect rather than progress linearly, or Buddhist mindful presence practices that cultivate temporal depth through conscious attention.
At 50, I find myself drowning in chronos—the relentless march of sequential time—while desperately reaching for those increasingly rare kairos moments that once seemed to stretch endlessly in youth. The question becomes not merely why time accelerates, but what we lose when chronos overwhelms kairos—and whether we can reclaim our capacity for meaningful time in an accelerating world.
Bergson’s Revolutionary Insight
This tension between chronos and kairos, which the Greeks intuited, found its most sophisticated philosophical expression in Henri Bergson’s revolutionary insight about time’s dual nature. The French philosopher’s eureka moment came through analyzing time in physics: “I saw, to my great astonishment, that scientific time does not endure.”
This was revolutionary because Bergson challenged the dominant scientific view that time could be measured and understood like space. In his seminal 1889 work Time and Free Will, Bergson first articulated this distinction, which would later lead to his famous 1922 Paris debate with Einstein about the nature of temporal reality. He argued that reducing time to measurable units fundamentally misrepresents its nature as lived experience. Bergson distinguished between “objective time” (the time of watches and calendars) and la durée (“duration”)—our lived, flowing temporal experience.
For Bergson, authentic time is duration—our lived, flowing experience—while mechanical clock time is merely a spatial representation of temporal flow. Duration is an inherently continuous and interconnected process that cannot be broken into separate moments. Unlike spatial objects that occupy distinct locations, moments in lived time flow into each other—our past colors our present, which anticipates our future, creating seamless experiential continuity.
This phenomenological insight profoundly influenced later thinkers like Husserl and Heidegger, who built upon Bergson's understanding of lived time to develop richer accounts of temporal consciousness and human existence.
This distinction becomes crucial when understanding midlife temporal anxiety. Bergson observed that we mostly ignore la durée because “objective time” is far more practical. But we recognize the difference when they diverge: an hour’s wait at the dentist drags on endlessly, while sitting on a fallen tree kissing someone you love flies by.
At 50, this distinction becomes painfully apparent. Our days blur together in objective time—meetings, deadlines, routines—while the durée moments that once defined our youth become increasingly rare and precious. Understanding Bergson’s durée reveals what we’re truly mourning as time accelerates: not just the passage of hours, but the loss of lived, meaningful temporal experience.
The Weight of Finitude: Heidegger’s Temporal Authenticity
This confrontation with temporal acceleration carries existential weight that the German philosopher Martin Heidegger mapped with startling precision. His concept of Sein-zum-Tode (“Being-toward-death”) reveals why approaching 50 is qualitatively different from earlier decades—not just because time seems faster, but because awareness of finitude fundamentally alters how we inhabit time.
For Heidegger, authentic existence requires confronting our radical finitude. Unlike other beings that end, humans exist with conscious awareness of their mortality—a condition that transforms every temporal choice into an existential one. This isn’t a morbid preoccupation but an ontological awakening. When we truly grasp that our time is limited and non-renewable, each moment gains weight and urgency it never possessed in youth’s seemingly infinite horizon.
At nearly 50, I recognize this shift viscerally. The mathematical reality—that each year represents an ever-smaller percentage of my total existence—carries existential force precisely because it makes finitude concrete rather than abstract. Heidegger argued that most of us flee this awareness through what he called “everydayness" (Alltäglichkeit)—losing ourselves in routine, social roles, and the “they-self" (das Man) to avoid confronting our mortality. But midlife often shatters these protective illusions, forcing us into what he termed “authentic temporality.”
Equally relevant is Heidegger’s concept of Geworfenheit ("thrownness")—the recognition that we are thrown into existence without having chosen our circumstances, historical moment, or fundamental conditions. I didn’t choose to experience temporal acceleration at 50; I’m thrown into this accelerating temporal experience just as I was thrown into existence itself. This thrownness isn’t victimhood but ontological condition—the basic fact that we must make meaning within circumstances we never selected.
This philosophical insight illuminates why temporal acceleration feels so unsettling. We’re not just experiencing faster time; we’re confronting the thrown condition of aging consciousness in a temporal reality we cannot control. Yet Heidegger suggests that confrontation with thrownness and finitude opens possibilities for authentic existence. When we stop fleeing our mortality and temporal limits, we can inhabit time more deliberately—choosing how to spend our finite moments rather than simply consuming them.
This connects directly to the chronos-kairos distinction. Heidegger’s authentic temporality resembles kairos—moments of conscious choice and meaningful action undertaken with full awareness of their irreplaceability. Chronos becomes the everyday time we flee into to avoid existential confrontation. At the same time, authentic temporal experience emerges when we embrace our finitude and freedom to choose how we meet it.
The approaching milestone of 50 thus represents more than mathematical acceleration—it’s what Heidegger might call a moment of “authentic resoluteness” (Entschlossenheit), where awareness of finitude creates the possibility for more deliberate, meaningful temporal existence. The question becomes not how to slow time’s passage, but how to inhabit it with greater authenticity and intention.
This existential understanding of temporal acceleration finds surprising validation in neuroscience, where researchers have mapped the biological substrates of what Heidegger described phenomenologically.
The Neuroscience of Temporal Compression
But how exactly does this philosophical insight align with what neuroscience tells us about temporal perception? The answer lies in understanding how our brains construct what Bergson called la durée—and why this construction changes dramatically as we age. What Bergson intuited philosophically—that lived time differs fundamentally from measured time—now has a neural explanation.
Modern neuroscience reveals that our sense of flowing time emerges from complex neural networks, particularly the interaction between dopamine and glutamate in cortico-striatal circuits—the brain's timing pathways that connect our prefrontal cortex (involved in planning and decision-making) to deeper structures like the striatum (which governs movement, motivation, and temporal processing). These circuits work alongside our suprachiasmatic nucleus (the brain's master biological clock, located in the hypothalamus) and operate according to what researchers call the "striatal beat frequency model"—a theory proposing that different groups of neurons fire in rhythmic patterns at various frequencies, like multiple metronomes running simultaneously, and our brain interprets the interactions between these neural rhythms as our sense of time passing.
Think of it as your brain's internal orchestra: different neural sections keeping different beats, and your conscious experience of time emerges from how these rhythms synchronize or drift apart. These timing circuits help us estimate how long events last and sequence experiences in memory. But here's the crucial point: these neural timing systems show decreased dopamine sensitivity with age, particularly in the D2 receptors that affect our ability to judge intervals accurately, while our prefrontal cortex—essential for complex temporal processing—shows reduced activity in older adults.
Psychologists distinguish between two types of temporal judgment that involve different neural circuits: prospective time (experiencing duration as it unfolds) and retrospective time (remembering how long something lasted). This distinction helps explain why anticipating a dentist appointment feels eternal while remembering a wonderful vacation seems brief.
When we’re young, novel experiences flood these timing circuits with dopamine, the neurotransmitter that signals novelty and reward. Simultaneously, glutamate facilitates the neural plasticity that creates detailed memory traces. Each new moment demands full neural attention, creating rich, detailed temporal experiences—Bergson’s pure durée. The first time you drive alone, your first kiss, moving to a new city—these experiences stretch subjective time because they overwhelm our neural networks with novelty, forcing intensive processing that creates dense memory traces.
However, this process is complicated by what psychologists call "Block and Zakay's attentional gate model"—cognitive load affects how much attention we can devote to temporal processing. When overwhelmed by information, our internal clock literally slows down. Additionally, emotionally significant events expand subjective time regardless of age, which explains why trauma can feel endless while positive flow states seem to pass instantly.
However, as we age and accumulate experience, fewer events qualify as novel, and dopamine and glutamate systems decline in efficiency. Our brains, evolved for efficiency rather than meaning, begin compressing familiar patterns into what neuroscientists call “chunking”—bundling routine experiences into single processing units that require minimal conscious attention. What once needed navigating each turn and noticing each landmark now happens on autopilot—collapsing a 20-minute commute into a single undifferentiated unit: home-to-office.
Interestingly, clinical conditions reveal how disrupted temporal processing affects lived experience. Depression typically slows subjective time, making minutes feel like hours, while anxiety accelerates temporal perception. ADHD often involves temporal processing deficits that make it challenging to estimate durations accurately—insights that ground our philosophical inquiry in practical human struggles.
Our limited attentional resources also shift with age. What psychologists call “inhibitory decline” makes it harder to filter irrelevant information, ironically accelerating chunking as our brains work to manage cognitive overload. Chronic stress further compounds this compression, as cortisol interferes with memory consolidation, leaving fewer distinctive traces.
There’s also a fascinating phenomenon called the "reminiscence bump"—we remember ages 15-30 most vividly, not just because these years were proportionally larger, but because they contained our first significant life experiences: first love, college, and early career. This complicates simple proportional models of temporal acceleration.
This neural reality has inspired researchers to develop more sophisticated mathematical models. Theoretical models, such as those proposed by Adrian Bejan, a professor of mechanical engineering, attempt to quantify this phenomenon in his 2019 paper “Why the Days Seem Shorter as We Get Older“, suggesting that the perception of accelerated time is based on the declining rate of neural processing as we age. Bejan’s theory focuses on how physical changes in our aging neural networks slow visual information processing, creating a disconnect between measurable “clock time” and subjective “mind time.”
However, these equations, however refined, cannot capture what we lose: the capacity for temporal depth, for moments that expand consciousness rather than merely consume it. This neural compression manifests viscerally in midlife experience. At 50, entire weeks blur past without distinctive memory markers. Neuroscience explains this phenomenon: those vivid childhood memories formed when my brain’s dopamine and glutamate systems were optimally primed for novelty, while recent Tuesdays blur together as my aging neural circuits efficiently chunk routine experiences into undifferentiated units.
Neuroscience reveals a profound paradox. Understanding these mechanisms—knowing why familiar routines compress into efficient neural shortcuts and why dopamine-declined circuits process time differently—doesn’t diminish the experience’s existential weight. If anything, it deepens it. We’re not just losing time; we’re losing our neurological capacity to inhabit time richly.
This points toward a critical question that will haunt the rest of this exploration: in our digitally fragmented age, with constant interruptions and shallow attention, are we training our brains to compress experience even more rapidly than natural aging would dictate?
The Medicine of Presence
Hippocrates understood kairos as the critical moment in medical treatment—when intervention would be most effective. This medical wisdom speaks to something essential: not all time is equivalent, and the quality of temporal experience matters as much as its quantity.
Understanding the neuroscience of temporal compression makes this ancient insight more urgent. If dopamine-driven novelty naturally creates rich temporal experience, then consciously seeking novel attention and breaking routine patterns becomes a neurologically informed practice of presence. If our brains naturally chunk experience into efficient shortcuts, cultivating kairos becomes an act of neural resistance—consciously choosing novelty and deep attention over the brain’s default tendency toward automatic processing.
For Bergson, the richness of la durée depends on our conscious engagement—our willingness to resist automatic processing and attend fully to present experience. This requires agency: the deliberate choice to notice, stay present, and resist the brain’s evolutionary drive toward efficiency.
Just as physicians must cultivate their sense of kairos to know when to act, we must deliberately practice presence to resist temporal compression. The challenge at 50 is learning to inhabit kairos within chronos—to find those moments where time thickens with meaning despite the overall acceleration of lived experience.
This is the beginning of a larger inquiry into what “arriving” in life means—not reaching some destination, but learning to inhabit each moment fully despite time’s acceleration. The question becomes not how to slow time, but how to cultivate what we might call “temporal depth”—the capacity to experience moments as rich, meaningful, and expansive despite their brief duration. How do we make the compressed time we have burn with greater intensity and significance?
This quest will take us through fragmented attention that accelerates compression, the bewildering pace that overwhelms our temporal circuits, and ultimately toward practices that might restore our capacity for meaningful time—not by stopping the clock but by changing how we inhabit the moments we have.
This piece opens a series of personal reflections called “Midlife Mediations” on turning 50 next year. It explores how we inhabit time, create meaning, and understand what it means to “arrive” in life. Future articles will examine our fragmented attention, the urgency of now, and the practice of imperfection in our quest for temporal depth.