But as a Jew, he would be banned from any such activities.

https://en.wikipedia.org/wiki/History_of_the_Jews_in_the_Byzantine_Empire#Theodosian_Code:_404%E2%80%93527

https://en.wikipedia.org/wiki/History_of_the_Jews_in_the_Byzantine_Empire#Justinian_Code:_527%E2%80%93565

My current impression is that late antique Rome indeed had [by ancient standards] a larger bureaucracy than it could handle, although you could see why it evolved out of the failure of the previous state model in the crisis of the 3rd century. Much larger and more costly army than the early empire too.

If anything, late Rome could be used as an example of maintaining huge, expensive, normally effective military forces that are still not quite equal to the threats facing them, and used in such a way as to neglect ultimately more critical threats that work in the background. Plus a degree of rust out towards the end as the tax base shrinks, ultimately reducing the effectiveness too. Hmmm.

They moved to a border troops/mobile reserve model for reasons, and it’s not clear to me whether that weakened the overall Rhine defenses enough to by itself explain what happened in 405-6, but maybe.

They definitely ended up in a position where they had ceded so much territory within the western empire to German federate rule that they had no tax base to maintain their military capacity to subdue those same Germans.

On the other hand the East had some resilience. IIRC, they massacred all the German troops in their army and replaced them with citizen Isaurians.

Somewhere not too long ago I read this exchange between Bryan Ward-Perkins and Peter Heather, who did two of the more interesting books of the 2000s https://blog.oup.com/2005/12/the_fall_of_rom/

As well, the Roman Empire’s preemption of all things defense-related? Along with the upper-class reluctance to participate in the defenses…? That left all of Europe unable to take care of its own defenses when the barbarians came knocking at the gates. Had the Gauls been left alone, instead of domesticated like so many farm animals…? Odds are, the great migrations would have hit more than just token resistance at the borders. Roman Imperial neglect of the military and defenses along the borders was immoral to the extreme–On the one hand, they denied the conquered citizenry of Roman Europe the ability to defend themselves, and then abnegated Imperial responsibility to do the job. The invaders found little effective resistance in Roman Europe, and indeed, also found that they were welcomed due to the extremely punitive tax structure of Rome being gone…

When you look at it in a certain light, the whole thing is amazingly similar to what we have going on today, only with the US cast as the protector that’s enabled European bad ideas about such things to flourish. What’s that line about history repeating itself, first time as tragedy and second time as farce…?

I think we’re well into the “farce” stage of things, as the Euros enable their own destruction behind our shield. Maybe NATO was a really bad idea, and we should have let the Soviets have the place–The Western European nations would likely have a better sense of what they’re risking, and after the inevitable fall of the Soviets, they’d be going through the same sort of semi-Renaissance that Eastern Europe is going through…

For better or worse, I’ve become more fatalist. Save your own civilization before it falls, or resign yourself to carrying the torch or rebuilding later.

That and I slipped out of the idea that the fall of Rome was an unaccountable, preventable development rather than being both the likely end of any civilization and the definable product of multiple forces at play in the times. I’ll leave it to continuing historical debate which ones these were, although additional work was done in the 2000s.

If anyone watched Stargate SG1, there was a moment at which Daniel Jackson throws away a line about how if it hadn’t been for the Dark Ages, man would have been exploring the stars centuries ago. It’s a seductive line and related to the idea behind Lest Darkness Fall, but it has some of the qualities of “if my granny had wheels she’d be a wagon.”

That and I tend to think Mark Twain was more right than deCamp. Any of us who tried this would end up being the Connecticut Yankee in King Arthur’s Court.

Not that time travel alternate history is not fascinating. I’m still haunted by some of Poul Anderson’s Time Patrol stories — Delenda Est and The Sorrows of Odin the Goth, for two.

Lest Darkness Fall by L. Sprague de Camp. “An archaeologist is transported from Rome, in the time of Mussolini, to the 6th century and tries to prevent the fall of the Roman Empire.”

Do not, however, look to me volunteering to run the thing in the field. I remain convinced that there are a bunch of stumbling points for all of it, that we just don’t see.

I think your best bet, were you to want to try this out, would be to take yourself and a bunch of your friends back to some isolated part of the world, and then set your own society up.

Which, come to think of it, may explain the Denisovians or the Tocharians…

If you can get over the initial hurdles (language, xenophobia, dysentery…) without career-ending misfortune, and get some contacts and a month or so of savings, I think it would be a lot more promising to try to sell various things that we moderns take for granted. Make a knit cap or a pair of knit socks. Learn a locally available musical instrument well enough to adapt catchy modern musical melody and/or harmony and/or rhythms: anything that made a good movie score (Toccata in D minor intro, or the Mozart concerto used for Elvira Madigan, or Scott Joplin) might be worth trying. Chase down a serious surveyor, who judging from the archaeological tidbits I’ve heard of will likely be using trigonometry, and will not be using Arabic numerals, and see whether you can cut a deal to ease his pain.

Also, if one could avoid the various social gotchas that tend to grow around serious gambling, elementary probability theory would give any modern from a mathematical field like economics a serious advantage in gambling with cards or dice or wheels or other inanimate objects (as opposed to gambling on gladiators or racing or whatever). And, if you don’t want to do the gambling yourself, I bet you’d have a much better chance of getting people to pay you to teach that than getting people to pay you to teach economics.

With a year or so of savings (and, ideally, a reputation that helps you get a patron to buy the expensive materials), you might try selling some I’m-a-savant publicity prestige sponsorship package based on flashy or profound eighteenth century and nineteenth century tech: Leyden jars, man-carrying hot-air balloons, solar spectroscopy, the galvanic frog leg contraction trick, Pasteurization, or (assuming there’s interest in breeding farm animals or war/racing/whatever specialist horses) even Mendelian genetics. None of those are sure winners, but all seem more promising than trying to sell economics or logistics or marketing or mnemonic methods or similar nonvacuous but specialized and shallow things.

And if none of *that* floats your boat, and you really want to teach theory, I think even if you’re an economist, you might have a better chance of getting supported for teaching what you know of stuff related to Newtonian mechanics — mechanics itself, plus calculus, applications to planetary observations, and various tabletop demos. It is a deeper field with more sharp knowledge, it is more obviously widely applicable, and whether you have ten minutes to do it or ten weeks to do it you have a much better chance of demonstrating to a prospective student that you know things which are nontrivial and potentially useful.

I do know from my reading that there’s a process of adaptation which goes on with any new disease; syphilis, for example, has become far less destructive as the host/disease adaptation process goes on–As someone once observed, it’s a damned stupid parasite that kills the host it lives off of…

So, maybe you’d encounter a much more damaging version of the disease you’re immune to, in its attenuated form, and die because of that? I don’t know enough to say, and maybe nobody does, as we haven’t “run the experiment”. Although, you could say we’ve done that in a somewhat analogous form, when a new disease is brought into an unexposed population like the natives here in North America.

Kinda makes you wonder, though… What if we’re seeing signs of time travel with some of these disease pandemics like what killed off all the Central American native populations after Cortes initial successes against the Aztecs? It’d be darkly humorous if that was a reality–Historical time-traveller goes back to observe their favorite hobby-horse, and manages to kill off their own history by doing so.

It’d be like going back to observe WWI as it happened, and taking some future pandemic-capable disease with you, and instead of observing the start of the new world order, you inadvertently managed to kill off the people who created all that cool stuff with the Spanish Influenza Epidemic.

Could explain why we don’t have time travel; anyone who actually manages to invent it goes back and forth in time, spreading disease, and manages to kill off everyone who would lead to time travel being invented…

With regards to the old-timers’ effect on the time traveler, though, I’m not so sure that having immunity to modern forms of a disease grants immunity to old strains. It seems more like it would be a sliding scale as you go back in time, becoming more and more lethal to the time traveler as the microbial fauna had less and less overlap with what they developed in. Caveat that I’m no microbiologist and this could easily be wrong. I’m interested enough that I’m going to pose the question to a friend of mine who is. I’ll post an answer if I get one.

I’m familiar with the idea, but I don’t think I’ve ever really seen it articulated as that particular construct.

As to the immunity thing… Consider this: Your modern immune system is attuned to more evolved versions of disease than the ancients, and what your immune system treats as no big deal would probably produce pandemic results in an ancient setting. We see this all the time, in the real modern world–Look at what the Nepalese peacekeepers managed to do to Haiti, with their version of cholera, for an example.

Hell, imagine taking a modern variety of the flu back in time to a place where there was no evolved immunity to it… Although, that could make for an explanation of where some of these unexplained plagues in the ancient world came from. “Hey, we’re going back in time to see all the historically significant developments in the Byzantine Empire…”. “Oh… Uh, yeah… That pandemic which our new timeline calls the Plague of Justinian, that set Islam up for success…? That was us; the flowering of the Byzantine Empire didn’t happen, ‘cos we done killed all the people that made it happen…”.