I keep seeing these economic treatments of "how much progress has accelerated" (and have been seeing them for some 30-40 years now myself), and ... I'm starting to feel a case of three-card monty or the travelling dime problem -- keep moving the pieces quickly enough so that the audience^Wmarks don't spot the trick.

First off: yes, absolutely, the cost of provisioning and operating electronic memory data storage and processing has fallen phenomenally. DeLong makes that point abundantly clear:

in 1957, the transistors in an iPhoneX alone would have ... cost 150 trillion of today's dollars: one and a half times today's global annual product ... taken up a hundred-story square building 300 meters high, and 3 kilometers long and wide ... drawn 150 terawatts of power—30 times the world's current generating capacity

But let's look at those comparisons right there.

The iPhone X costs $1,000, and for easy math I'll assume all of that is the memory storage (this is wrong, but it's not horribly wrong, on an orders-of-magnitude basis). If the 1950 cost was $150 trillion, then the price has fallen by at least 150 billion fold. (And in fact it's fallen more, because there's more than just memory in the device, so my easy math understates the case.)

Global GDP in 1955, or more accurate, GWP, was $5.4 billion. As of 2016 it was about $80 billion, or, just for round numbers, lets call that $5 billion and $100 billion.[1]

The multiplier is a factor of 20. Which, if I check maths, is somewhat less than 150 billion. Which is to say that whatever's been strapping white lightning to our capacity to chunk out memory circuits has not been strapped to the global economy as a whole.

Measures of the total built environment are difficult to come by, and even proxies for that seem at best obscure. Since DeLong specifies the idea of a 100-story-tall building, though, there is at least one interesting statistic that can be readily produced. Up until 1970, there was precisely one such building, and it was the Empire State Building, which held that record from 1931 until 1972 (at which time the newly completed World Trade Centers in New York City claimed the crown).

https://en.m.wikipedia.org/wiki/History_of_the_world%27s_tal...

Naturally, there's been some contention for that prize since. A total of four additional tallest structures are listed: the Sears Tower (completed in 1974), Patronas Towers, Taipei 101, and Burje Khalifa. If we look at the list of the world's tallest buildings, and use the ESB's 381 meter height as a minimum qualification, there are by my count 37 such structures. Again, this seems slightly less than 150 billion.[2]

Finally, energy consumption. In 1955, this was, roughly, 100 exajoule. In 2017 this is, roughly, 500 exajoule. The multiplier would be then ... 5. A number somewhat less than 150 billion.[3]

The question which arises out of this is what is it about information technology that allows for a 150-billion-plus increase in capabilities, whilst total GWP (20x), skyscrapers (37x), and energy (5x) have seen far, far, far less expansion?

There's another question which asks if we're actually including full costs, which I'll note but leave off the table for this discussion.[4]

But the question I would like to ask is what additional service value is being provided for all that the iPhone offers?

Consider that it is, ultimately, an information delivery device. And that the information end-consumer, the human tethered to it, has an almost ludicrously low consumption capability. Sure, you can deliver gigabytes or terabytes of source data to a human, but the amount of that which is absorbed, over the course of a day, amounts to ... a few megabytes, at most. And we're talking single digit values here.[5] What the iPhone can deliver is video, audio, images, and text. Through on a viewport roughly the size of a 3x5 index card. The equivalent 1955 technologies it replaces are a notebook, a telephone (and probably some form of answering service or secretarial pool), the not-yet-invented transistor radio, a deck of cards or pocket game, a newspaper and/or magazine, a paperback book, a letter. A pile of index cards itself.[6]

And ... the iPhone X carries any number of unintended consequences: the loss of liberal democracy, undermining a century-old tradition of advertising + subscriber based print media, journalism, adtech, concentration, possibly an entire generation.[7] Unintended consequences are a real bitch.

Delong's calculus is exceptionally insufficient.

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Notes:

1. Wikipedia. Which, coincidentally, is citing one Bradforth DeLong as its source.
https://en.m.wikipedia.org/wiki/Gross_world_product

2. https://en.m.wikipedia.org/wiki/List_of_tallest_buildings

3. Gail Tverberg, after Vaclav Smil and BP: https://ourfiniteworld.com/2012/03/12/world-energy-consumpti...

4. Much of this revolves around the question of natural capital accounting. The good news is that this is entering mainstream economics, see the World Bank for example. The bad news is that it's still improperly founded. Steve Keen's work on energy in production functions is also of interest, though that admits yet another factor.

5. Consider audio. The human limit of perception is roughly 20 impules per second, a/k/a 20 Hz, which is the threshold at which beats become a tone. Given 86,400 seconds/day, at 20x, we've got 1.7 million bits of data, or 216 KB of audio-encoded pulses. For printed material, a 250 words/min reading pace is fairly typical, which works out to 2.16 MB/day, sustained for 24 hours.

6. a/k/a the Hipster PDA: http://www.43folders.com/2004/09/03/introducing-the-hipster-...

7. https://www.theatlantic.com/magazine/archive/2017/09/has-the...