East Rock rises abruptly from the flat New Haven city streets that surround it. Approaching from the south or the west, its diabase ramparts rear up forbiddingly.

While most of the East Coast’s ranges date to the continental collisions that assembled Pangea, the igneous intrusions and the sedimentary rocks of central Connecticut are roughly half as old and stem from Pangea’s demise. East Rock Park is a Jurassic Park, and two hundred million years ago, the rifts that eventually grew to become the Atlantic Ocean were opening just south of town. The rift valley floor was sinking, sediment was accumulating to fill the growing depression, and the sill of lava that eventually solidified into East Rock was squeezing out in a thick viscous sheet.

Several miles north of East Rock, an extensive road cut reveals layers of sediment from near the Jurassic-Triassic boundary. Beds of reddish sandstones and fused conglomerates of mud and pebbles are tilted at an angle of about 10 degrees, a remnant of the sinking and foundering that the rock layers suffered after they formed. The strata are varied and clearly visible, representing sediments that accumulated in a rift valley that alternated between a seasonal playa during dry periods and long-lived lake bed during wet periods.

Near the dawn of the Jurassic, New Haven was located in the tropics. During rain-soaked epochs, the shores of the rift lakes were a year-round riot of green with pterosaurs soaring in the skies. Perhaps there was nothing overt in those long-departed scenes to suggest that the end-Triassic extinction was either near or was already underway. And now, two hundred million years later, the layered record of ancient climate change stands mute and unvarying as the engines of loaded dump trucks roar and strain against the freeway grades.

A close look at the road cut shows a banding pattern that starts to repeat as one ascends from the lower exposed layers at the left of the photo to the upper exposed layers on the right. A look at the literature indicates that the rate of deposition in Central Connecticut 200 million years ago was about 1 millimeter of sediment per year, so the span recorded in the exposure is about 20,000 years. The repetition reflects one precession cycle of Earth’s spin, which dictates how the seasons align with the varying distance from the Sun stemming from the eccentricity of Earth’s orbit.

The sedimentary record in the New Haven area from the period of Pangea’s rifting is continuous over something like 20 million years, and the tilted layers of rocks fill Connecticut’s central valley to depths measured in miles. Cores drilled through this colossal lens of sediment reveal that Earth’s ancient orbital eccentricity variations are faithfully recorded in the strata.

In the course of an afternoon, with a laptop and the Rebound code, one can integrate the full Solar System back to the moment when the hardened lava that makes up present-day East Rock was glowing toothpaste-red and pushing its way into the then-newly lithified strata.

Looking back over the past five million years, Earth’s secular eccentricity variations are plainly apparent. In particular, the ~400 kyr envelope produced by the beating of the Venus-dominated g₂~7.2”/yr and Jupiter-dominated g₅~4.3”/yr secular frequencies is clearly visible.

This ~400 kyr (or more precisely, 405 kyr pattern) has been remarkably stable over Earth’s history. Running the clock back to the dawn of the Jurassic 200 million years ago, it shows no real change in character from the present. The plot just below runs for 10 million years forward from the formation of East Rock. A low-pass filter has been applied to the full eccentricity variation (shown by the light orange curve) to show the 400 kyr variation swinging up and down. Just as it does today.

In the late 1950s, orbital measurements of the Martian moon Phobos were interpreted to suggest that the satellite’s orbit was decaying faster than expected. This prompted the Russian astrophysicist Iosef Shklovsky to propose a “thin sheet metal” structure for Phobos, thereby explaining its anomalous acceleration and implying that it is of artificial origin.

The ensuing jolt of public interest in this hypothesis spurred an invigorating side-line for Shklovsky, who progressed from a drably monochrome list of equation-heavy papers — replete with sober titles such as On the Nature of the Fine Structure of Emission of Active Regions on the Sun — to glamorously teaming up with Carl Sagan to (among other things) advocate examination of “paleocontact” with extraterrestrials and for scrutiny of myths and religious lore for indications of influences from out there.

My guess is that it’s quite likely Shklovsky was well aware that promoting a field that later generated efforts such as Erich von Daniken’s Chariots of the Gods, and the History Channel’s Ancient Aliens was largely just for fun. There is, after all, no harm in broadening the public’s exposure to a wide variety of ideas. Right?

As described on his Wikipedia page, on the occasion of a visit to the Berkeley Astronomy Department, Shklovsky was memorably asked by a graduate student if UFO sightings are as common in the Soviet Union as in the United States.

“No,” he replied. “In this area the Americans are far more advanced than us.”

Last weekend, there was an engrossing article in the New York Times.

Titled, ‘A Frankenstein’ that Never Lived, the piece’s top-line summary runs, “On Jan. 4, 1981, the effects-heavy production opened and closed on the same night. Forty years later, the creators revisit a very expensive Broadway flop.”

According to the article, prior to the open, hopes for success of the big-budget enactment of Mary Shelley’s 1818 classic had run high, but the show’s prospects were dashed in large and immediate measure by Frank Rich’s dreadful review in the Times. Rich’s write-up brims with both arch sarcasm and gut-punch lines such as, “we feel nothing except the disappointment that comes from witnessing an evening of misspent energy.” Reading the article, I can feel a queasy, visceral sympathy for everyone who worked on that production.

At the end of the last century, Fred Adams and I were riding high on our forecasts for the denouement of the entire cosmos. Our trade book — The Five Ages of the Universe — had, to our great thrill, just been published by an imprint of Simon and Schuster, and we were enjoying the modest acclaim that had proceeded from dividing the entire past and the entire future of the Universe into five thumbnail-friendly eras of time.

The sales, the buzz, and the idle dreams of pop-culture stardom all came to a crashing halt from one day to the next when the New York Times ran its review of our book. I can recall the sinking feeling at the moment when our agent called Fred to let us know what had happened. “Brace yourself.” I think that was what she said.

Dick Teresi’s review was entitled, “The First Squillion Years”, and the title telegraphed the intent. It starts out bad, it gets progressively worse, and finally ends rather crushingly, with “Imagine an astronomer looking back at us ages hence. Perhaps he can read the bound galleys in my hand. Maybe he will be kinder than I have been here.” Yikes.

It’s amazing, however, how quickly one recalibrates. The book tour that had been in the cards was scaled way back to a handful of local appearances, with Borders Books in Ann Arbor standing in as the high point. Sales dried up. Just like that, I was back to trying to find bugs in Fortran codes. Over time, it became clear to me that it was almost certainly just as well.

Rather amusingly, the distant future is currently having something of a moment. There have been several new trade books on the topic, including at least one that got a review in the Times that was entirely different in tone that the one we drew. And then, a fantastic coda for the whole episode arrived unexpectedly a week or two ago as I was leafing through a recent issue of the New Yorker.

I’ve always enjoyed Roz Chast’s cartoons. She has a great sense of humor. It was oddly gratifying to see that she’d somehow been seized to lift out our eras and our thumbnails, elevating them to a full-page cartoon.

Time has a way of sliding by. More than five years ago, I wrote a blog post with a suggestion for a new cgs unit, the oklo, which describes the rate per unit mass of computation done by a given system:

1 oklo = 1 bit operation per gram per second

With limited time (and limited expertise) it can be tricky to size up the exact maximum performance in oklos of that new iPhone 12 that I’ve been eyeing. Benchmarking sites suggest that Apple’s A14 “Bionic” SoC runs at 824 32-bit Gflops, so (with Tim Cook in charge of the rounding) an iPhone runs at roughly a trillion oklos. Damn.

Computational energy efficiency also keeps improving. Proof-of-work based cryptocurrencies such as Bitcoin have laid the equivalency of power, money and bit operations into stark relief. The new Antminer S19 Pro computes SHA-256 hashes at an energy cost of about one erg per five million bit operations, a performance that’s only six million times worse than the Landauer limit. There is still tremendous opportunity for efficiency improvements, but the hard floor is starting to come into view.

For over a century, it’s been straightforward to write isn’t-it-amazing-what-they-can-do-these-days posts about the astonishing rate of technological progress.

Where a calculator like ENIAC today is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have only 1000 vacuum tubes and perhaps weigh only 1½ tons.

And indeed, there’s a certain intellectual laziness associated with taking the present-day state-of-the-art and the projecting it forward into the future. Exponential growth in linear time has a way of making one’s misses seem unremarkable. “But I was only off by a few years!”

Fred Adams was visiting, and we were sitting around the kitchen table talking about the extremely distant future.

We started batting around the topic of computational growth. “Given the current rate of increase in of artificial irreversible computation, and given the steady increase in computational energy efficiency, how long will it be before the 10¹⁷ Watts that Earth gets from the Sun is all used in service of bit operations?”

As with many things exponential, the time scale is startlingly sooner than one might expect: about 90 years. In other words, the long-term trend of terrestrial economic growth will end within a lifetime. A computational energy crisis looms.

In any conversation along such lines, it’s a small step from Dyson Spheres to Kardashev Type N++. If you want to do a lot of device-based irreversible computation, what is the most effective strategy?

A remarkably attractive solution is to catalyze the outflow from a post-main-sequence star to produce a dynamically evolving wind-like structure that carries out computation. Extreme AGB (pre-planetary nebula phase) stars have lifetimes of order ten thousand years, generate thousands of solar luminosities, produce prodigious quantities of device-ready graphene, and have photospheres near room temperature.

We (Fred and I, along with Khaya Klanot and Darryl Seligman) wrote a working paper that goes into detail. In particular, the hydrodynamical solution that characterizes the structures is set forth. We’re posting it here for anyone interested in reading.

As we remark in the abstract, Possible evidence for past or extant structures may arise in presolar grains within primitive meteorites, or in the diffuse interstellar absorption bands, both of which could display anomalous entropy signatures.