Universities tell you to think in centuries.
Markets force you to think in quarters.
But your success in life and capital leverage itself runs on something in between — the 30- to 50-year idea cycle: long enough to build a dynasty, short enough to matter before entropy sets in.
If you understand shelf life — of disciplines, of media, of influence — you can time your bets better than almost anyone around you based on your current age.
I. Every Subject Has a Half-Life
Knowledge doesn’t age gracefully; it decays like radiation.
| Subject | Typical Half-Life (Relevance of Core Ideas) | Notes |
|---|---|---|
| Mathematics | 500+ years | Euclidean geometry, algebra, calculus, probability — nearly timeless frameworks. |
| Philosophy / Logic | 200–500 years | Core reasoning about knowledge and ethics never expires, only reinterpreted. |
| Physics | 100–200 years | Newton still valid under most conditions; relativity and quantum refinements persist. |
| Economics | 50–100 years | Core theories (incentives, markets, trade-offs) endure ~50 years before major paradigm shifts (Keynesian → Monetarist → Behavioral → AI-driven). |
| Computer Science (theory) | 50–100 years | The “physics of information.” Turing, Shannon, von Neumann will remain canonical for centuries, though applied layers decay faster. |
| Engineering (mechanical, civil, electrical) | 30–70 years | Fundamentals stable for decades, tools and standards refresh every generation. |
| Biology / Medicine | 30–50 years | Molecular discoveries and ethics evolve but base anatomy and evolutionary theory are durable. |
| Political Science / Sociology | 20–50 years | Institutions and ideologies shift faster; context-dependent. |
| Business / Marketing / Management | 3–7 years | Rapidly obsoleted by tech and cultural cycles. |
When you’re in 4-year university, the goal isn’t to study what’s eternal — it’s to study what endures just long enough to pay off across a career, roughly 30 to 50 years.
That’s the half-life of market-relevant knowledge in advanced economies.
Mathematics and philosophy are too abstract to monetize directly; marketing and design age too fast.
But disciplines like economics, computer science, engineering, and finance hit the sweet spot — they evolve slowly enough to retain core logic for decades, yet fast enough to compound into real-world leverage.
If you major in a subject whose half-life is shorter than your loan repayment period, you’re not educated — you’re just paying for obsolescence.
Don’t study what’s eternal.
Study what survives long enough to cash out.
In market economies, that’s 30–50-year knowledge — not 500-year philosophy, not 5-year hype.
II. Every Media Consumption Has a Shelf Life Too
We don’t just live inside disciplines; we live inside formats of thought.
| Medium | Average Mental Retention | Cognitive Depth |
|---|---|---|
| Tweets / Shorts | ≈12 hours | Reflexive, pattern-priming |
| YouTube / Podcasts / Essays | ≈5 days | Narrative, associative |
| Books / Long Reads | ≈3 years | Reflective, conceptual |
| Textbooks / Ideologies / Theories | 10-30 years | Systematic, paradigmatic |
| Classic Books / Canon / Flag | 50–100 years | Archetypal, symbolic |
| Laws / Constitution | 5–300 years | Structural, institutional |
| Religions / Philosophies | 500–2,000 years | Mythic, civilizational |
| Spiritualism / Animism | 10,000-100,000 years | Archetypal |
The higher the cognitive load, the longer it survives — but the smaller the audience.
The trick is not to choose between them, but to chain them together:
Use short media to buy attention,
Use long media to store value.
That’s the real compounding loop of the 21st-century mind.
III. The Sweet Spot: 30–50 Years
In market-oriented societies, time itself is discounted like cash flow.
No investor prices returns beyond 30 years; no corporation survives unmutated for 50.
Anything longer stops being a strategy and becomes a religion.
That’s why the most powerful players — founders, financiers, statesmen — operate at the 30–50-year wavelength. Even Elon Musk, he became legacy figure after selling 30 years after he sold his firs game where he was at age 12.
They build things that outlast economic cycles but still convert to capital within their lifetime:
- Intel, founded 1968 → Peak leverage ~1990s.
- Google, founded 1998 → Peak leverage ~2020s.
- SpaceX, founded 2002 → Peak leverage ~2040s.
These are not eternal institutions. They’re half-century organisms — perfect for the human lifespan, perfectly tuned to the market’s memory.
IV. How to Play It Personally
In your 20s, minimize your monthly burn so you can think on a 30-year horizon.
Don’t chase the 3-year dopamine races; they’ll own you.
In your 30s, start compressing the horizon to 5–20 years — build brands, assets, and relationships that can ride one or two industrial waves (AI, biotech, climate, etc.).
In your 40s, tighten the loop again — compound what already works, harvest your reputation, and translate it into systems that don’t decay as fast as you do.
The key: keep your life horizon longer than the market’s, but shorter than the priesthood’s.
V. Beyond 50 Years: The Diminishing Returns of Eternity
Ideas that reach beyond 50 years — religion, ideology, moral philosophy — are civilizational glue, not leverage.
They don’t pay in this lifetime; they pay in narrative continuity.
Great for saints, terrible for founders.
The rational actor in a market civilization should borrow moral clarity from long horizons but invest only within compounding ones.
That’s 30–50 years for institutions, 5–20 years for products, 1–3 years for media waves.
Beyond that, you’re not an operator anymore — you’re a myth-maker.
VI. The Formula
If you want to win in modern time physics, knowledge acquisition should follow this:
| Age | Long (30–50y) | Medium (5–20y) | Short (1–3y) | What that means tactically |
|---|---|---|---|---|
| 10s | 70% | 20% | 10% | Load up on durable knowledge (math, CS theory, econ, logic). Minimal short-cycle hustle. |
| 20s | 50% | 30% | 20% | Translate foundations into real projects; keep burn low to preserve 30y options. |
| 30s | 30% | 50% | 20% | Commit to one secular wave; build brand/assets that can run a decade. |
| 40s | 20% | 55% | 25% | Double down on what compounds; prune experiments; professionalize distribution. |
| 50s | 15% | 45% | 40% | Harvest and defend: liquidity, ops excellence, succession, risk controls. |
| 60s | 10% | 30% | 60% | Maintain/optimize existing engines; minimal new 10y bets; high optionality. |
| 70s+ | 0% | 20% | 80% | Keep systems light and near-term; preserve energy, simplify, enjoy dividends. |
That’s how you stay relevant in the market and endure beyond a single hype cycle.
🧩 Closing Thought
In a world obsessed with velocity, durability is the rarest alpha.
The market rewards whoever can think one order of magnitude slower than everyone else — but not so slow they fossilize.
So study timeless knowledge.
Act in decadal bets.
Ship in quarterly loops.
And remember: in the economy of ideas and global competition of ever high IQ, time arbitrage is the only free lunch left.