I always wondered how far technology can go without advanced metallurgy. Clearly steam engines require good metallurgy, but the spinning jenny and the flying shuttle don't, do they? How much would those advances have changed the Roman world?
But I think the article did a good job of highlighting that technology developments occur out of local circumstances and requirements. I am no history scholar but I understand the Roman empire was expansive, space wasn't necessarily a constraint so there probably wasn't a huge demand to build larger and taller buildings it would have likely been easier to expand cities outwards rather than upwards.
There was a good documentary series I watched years ago called "Engineering an Empire" they had an episode about the technology of Carthage (Rome's great rival), the series pointed out the city of Carthage had large multi-story buildings shared by several families, kind of pseduo-apartment buildings from what the documentary explained there was much more constraints on space in Carthage as it was very desirable to live inside the city walls this led to the development of this type of construction style. Because of these tall buildings there were more advances in things like plumbing, which was different to what the Romans had at the time. The show also pointed out that Carthage placed more emphasis on Naval power so they had relatively sophisticated harbor design, shipbuilding industries etc.
(by 'digital computers' i mean the conventional, turing-complete kind, not special-purpose machines like the pascaline)
the romans (and the lydians before them) were routinely making a silver halide in order to refine gold from electrum; they used common salt, so they got silver chloride, which is a rather poor photographic material, but adequate to the purpose if your exposure is long enough. so photography was tantalizingly close for over 2000 years before it was finally achieved
because the first record of it is from pseudo-geber, evidently the romans didn't have sulfuric acid, which would have been quite useful for many things. but they had lead, glazed pottery, and nitrates, so they could have engaged in the chamber process
screws for actuating motion were documented by heron of alexandria in the early roman empire, and the screw press dates back further, so you could have built a micrometer
i don't know if you count iron smelting as 'advanced metallurgy', but electroplating was also tantalizingly close since the opening of the iron age; wire, iron, glazed pottery, vinegar, salt water, and copper were all available in every city, so you could easily have built a voltaic pile by putting a bunch of low-voltage cells in series — as some have speculated without evidence was done with the so-called 'baghdad battery', which dates from the sassanid period. but it's not clear what you'd plate onto what; perhaps you could tin-plate some iron, and then copper-plate the tin plating? gold and silver plating would have been out of reach
to me the most interesting aspect of this question is this: what advances could we make today, which in retrospect will puzzle our successors as to why we didn't make them for such a long time?
If we ignore the ‘minor’ issues of efficiency and longevity which would ‘only’ affect how practical the device would be I am not sure about that ‘clearly’.
So, let’s ignore all practical issues, and just try and build a steam engine that would provide some power for a decent period, ignoring efficiency.
Tensile strength to prevent pipes and the boiler getting torn apart by the steam pressure would be a main problem, I think.
There’s https://en.wikipedia.org/wiki/Wooden_cannon: “Wooden cannons have been manufactured and used in wars in many countries. The wooden parts were invariably strengthened with metal fittings or even rope.”, and (from World War One) https://en.wikipedia.org/wiki/Albrecht_mortar#Design: “The Albrecht mortars […] consisted of a muzzle loaded smooth bore barrel built from wooden staves and wound with galvanized wire for reinforcement”
Those likely didn’t work for long periods, but they did withstand fairly high pressures repeatedly.
So maybe, a boiler and pipes built with wood or bamboo, strengthened by rope could be made to ‘work’ at relatively low pressure for a while.
I would try to line the piping on the inside with clay to prevent steam from weakening the wood.
Next major problem: wood catches fire relatively easily. That’s at about 250°C, though, so there’s a range (about 520K vs 370K or 40% of room) at which steam can be created, but wood doesn’t burn yet.
Water boils at higher temperatures at higher pressure (https://www.engineeringtoolbox.com/boiling-point-water-d_926...), but that need not be a showstopper. The Newcomen engine doesn’t run on high pressure.
It also provides a ‘solution’ for another major problem, that of sealing the cylinder to prevent steam from getting out. https://en.wikipedia.org/wiki/Newcomen_atmospheric_engine#Te...: “The piston was surrounded by a seal in the form of a leather ring, but as the cylinder bore was finished by hand and not absolutely true, a layer of water had to be constantly maintained on top of the piston.”
So, I suspect you could build a steam engine without metals. It wouldn’t be efficient and would be prone to catching fire, though.