What is time for me?

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Just after Christmas, I was walking along a footpath near our home with my son and my grandchildren. The children were riding their scooters. It was late afternoon, really twilight, and darkness was beginning to encroach on the landscape.

We met an elderly man walking his dog in the opposite direction. He stopped to watch the children playing for a moment, then spoke to us. He said he had just spent a few days with his daughter, now forty-seven, whom he had not seen for a long time. He shook his head slightly and said, isn’t it strange how time flies? He told us he was now in his seventies, and that it felt like only a moment since she had been a small girl. And now, suddenly, she was a middle-aged woman.

We agreed, in the polite way people do, that time does indeed pass very quickly. He then continued on his way with his dog.

My son turned to me and said: So tell me, how does time look to you? Does your whole life now seem as if it’s gone by in a flash?

I stopped and thought about it. It seemed a more complicated question than it first appeared. I hesitated. The children circled, impatient to move on. We continued walking, diverted; I never gave him an answer at the time.

So what does my life actually look like, viewed from 75? Two observations come to mind.

The first is that I do have quite detailed memories of early childhood, of being very young, not much older than my grandchildren are now. I also have vivid memories of myself as a teenager, though they are episodic rather than continuous, and of my early twenties. But all of this lies fifty to sixty years in the past. The person I was then, now feels to me almost like a stranger, no more immediately accessible to me than any young person I might pass in the street. The memories exist, but I don't inhabit that earlier self.

The second observation concerns how time works for me now. In this respect, I do not think I am very different from someone at any age. I experience myself as present within a narrow temporal window: a sense of continuity extending back a few hours, perhaps not as far as a full day, and forward a few hours into anticipation. This limited span is what gives coherence to what I am doing and perceiving. Beyond that, whether into the past or the future, I have to consult external records: a diary, a calendar, photographs, documents. Those longer stretches of time don't form a unified totality in my mind.

It is as though I am walking along a very long, dark road with a small torch. The beam illuminates only my immediate surroundings. It gestures vaguely toward the darkness ahead and allows some reconstruction of the darkness behind, but I do not live in either of those regions. I live only in the illuminated patch, in the extended present.

Had I been able to formulate it at the time, that is what I would have said to my son.

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Pronatalism via Population Genetics

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Japan’s Population in the Next Thousand Years: Fertility, Assortative Mating, and the Shape of the Future

Two years ago, I wrote about the likely dynamics of population size in advanced capitalist countries, using Japan as my example. People note that in advanced countries the TFR is well below replacement, and then conclude that the populations in these countries are on the road to extinction. 'More migration,' they cry, showing that these discussions are essentially ideological rather than scientific.

The misfortune of the human race, if we can call it that, is that we evolved - mostly - to like having sex rather than babies. For most of our evolutionary history one thing led to another, however, so this didn't matter in Darwinian terms. However, modern capitalism has provided both effective contraception and many economic and personal incentives to do more interesting things than change nappies and deal with troublesome toddlers. This disconnection between sex and reproduction has led to the collapse in TFR.

However, a minority of men and women actually do want to have families - their emotional drives prompt them to have children despite the many distractions. Evolutionary theory tells us, of course, that future populations are constructed from their ancestors who reproduced, indicating that the prevalence of alleles which promote child-bearing directly will tend to increase in the population, generation by generation. 

This is selective advantage in operation: over time the population will be replaced by individuals who actually want to raise families. Let's see how this would work out in Japan.

Japan currently stands near 123 million people, yet its total fertility rate (TFR) is ~1.3, far below the ~2.1 births per woman needed for replacement. What follows sketches thousand-year outcomes using simple demographic arithmetic and population-genetic reasoning.

1. Straight-line decline

With TFR ≈ 1.3 and no offsetting forces, each generation replaces ~60% of itself. Headcount falls steeply: a remnant population of only tens of millions by 2200 and potentially a group in the hundreds of thousands by 3000. Nevertheless, this is a cultural and institutional contraction rather than a biological extinction risk although it's hard to see an advanced civilisation surviving in anything like its current form.

2. Genetics and slow selection

Completed fertility has modest heritability (≈0.2). Directional selection for a stronger “baby-drive” nudges fertility up by roughly +0.01 to +0.03 births per woman per generation. Timescale to reach replacement by genetics under the assumption of random partner selection alone is centuries; the population would likely bottom at a few percent of today’s size before any rebound.

3. Immigration as a bridge

Immigration offsets natural decrease for 1–2 generations because empirically, migrants arrive young and initially have slightly higher fertility. Likely convergence to host norms and global low fertility limit this as a century-scale fix. It buys time; it does not determine the endpoint.

4. Assortative mating as the hidden accelerator

Key dynamic: if a minority of strongly pronatal men and women mostly partner with each other, their subpopulation grows multiplicatively while the mainstream population shrinks towards zero. 

Japan’s future is not locked to straight-line decline. Assortative mating among pronatal families can bend the curve upward in roughly a century, especially with supportive culture and policy. 

Immigration buys time; automation and biotech buffer the costs of small populations. The decisive variables are partner choice, norm transmission, and targeted pronatal policy. These matter more than slow genetic drift alone.

In fact with the pronatal population exhibiting a TFR of 3.0 (three child families on average) it would take less than 250 years for Japan's population to bounce back to its current 123 million people.

SSBNs and the Not-So-Transparent Ocean

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The Coming Transparency of the Oceans

For half a century the oceans have been the last redoubt of nuclear stability. Ballistic missile submarines (SSBNs) slipped into the abyss, wrapped in silence and darkness, beyond the reach of satellites and spies. Their very opaqueness underpinned deterrence: no adversary could launch a first strike in confidence, because they could never be sure of neutralising the hidden fleet lurking under the sea.

That compact may be ending. Advances in sensing technologies - persistent undersea sensor networks, satellite gravimetry, AI-enhanced acoustic pattern recognition, quantum magnetometers - are converging on the once unthinkable. The oceans are becoming transparent.

Already navies test autonomous underwater vehicles that trail submarines indefinitely, while seabed listening stations proliferate. Even the tiniest acoustic or hydrodynamic disturbance, once lost in oceanic noise, can now be picked out by machine-learning systems tuned to signatures. Add global data fusion and the cloak of invisibility begins to fray.

If this process continues, and there is little reason to believe it will not, the traditional nuclear ballistic-missile submarine (SSBN) ceases to be the invulnerable guarantor of second strike. A technology once deemed eternal may soon be obsolete.

What then are the options?

States that rely on SSBNs face a stark choice. Some may fall back on hardened land-based silos or tunnels, forcing adversaries to allocate immense arsenals to achieve even partial destruction. Others may pursue mobile ICBMs, endlessly shifting across road and rail networks, complicating enemy targeting. Air-launched deterrents, those long-range bombers with nuclear cruise missiles, can be dispersed to many bases, or even kept aloft on rotating patrol.

More radical, scarier options exist. Nuclear forces could migrate upward into orbital platforms or downward into swarms of autonomous underwater drones, each carrying a small warhead, dispersed in numbers sufficient to overwhelm any tracking system. Others might bury warheads in civilian infrastructure (and embassy basements?), integrating deterrence into the sinews of commerce and transport—though at enormous cost to stability. Some may simply lean harder on the nuclear umbrella of allies, outsourcing their ultimate security; good luck with that, you might say.

Do these options stabilise, as submarines once did?

Not obviously. Hardened silos are fixed targets, vulnerable to concentrated attack. Mobile ICBMs and bomber fleets invite a premium on early warning, shortening decision times: use or lose. Orbital systems would upend existing treaties and encourage arms races in space. Swarms of nuclear drones raise command-and-control nightmares and the risk of unauthorised use. Embedding nuclear assets into civilian systems corrodes the distinction between war and peace.

The opacity of the oceans was not just a geographical fact but a political blessing. It allowed nuclear states to defer the abyss of hair-trigger readiness. If the oceans now grow transparent, that buffer erodes. 

Deterrence may survive, but in harsher, more brittle forms, where the line between stability and catastrophe narrows.

The coming transparency of the oceans therefore does not herald the fade-out of nuclear deterrence. It ushers in an age where that deterrence is noisier, more exposed, and far more dangerous.