German would probably have been the leading language of scholarship in general. That's because the research university with its doctoral degrees and dissertations was a 19th century German invention. The unpleasant events of the early 1940's ended that leadership and gave English its big opportunity.
But it had to compete with French, which was the language of general academic use, and even more important: of diplomacy.
It's interesting to speculate about the future of Mandarin Chinese as a scientific language. There are something like 1.3 billion people who can at least potentially read it (if they are literate), so it comes with a large readership built in.
Yes, they can read it, but only about half of the population can understand spoken Mandarin, and an even smaller number can speak it. Guangdong Chinese (still called "Cantonese" by many foreigners) and Shanghai Chinese (as well as several other versions of the language used in other regions) are considerably different from Mandarin in pronunciation, although the vocabulary and syntax are about 99% identical, which is why they can all read each other's writing.
Unfortunately, I get the impression that Chinese is still playing catch-up in terms of technical vocabulary, sometimes adopting English language technical jargon to their pronunciation and script.
This is true, but I think you're exaggerating a little. It's very difficult to borrow a word from English because the phonetics are incompatible. The scientific word that my Chinese teacher used to explain this was "vitamin," one of very few borrowings. It comes out as
wei ta ming, which means, literally, "only this gives life." Most other words are neither phonetic transcriptions nor clumsy translations. "Bicycle," for example, is
jiao ta che, "foot stride vehicle." Telephone is
dian hua, "lightning speech"--"lightning" is universally used for "electricity."
A big problem for Chinese is that despite its huge number of native speakers, it isn't truly a global language, being restricted to China, Taiwan and a few places like Singapore.
Sure, but as possibly the only person here who has actually studied the language and can carry on a simple conversation, the phonetics are just as big a problem--especially learning to use tones as phonemes rather than expressions of feelings.
So I can kind of imagine a situation where China becomes its own scientific world, with Chinese scientists writing in Chinese for Chinese readers, while the rest of the world scientific community still tends to operate in English. Of course there will be people in both China and elsewhere who do understand the other's language and will be watching for interesting publications, which will quickly circulate in translation. This is where machine translation potentially becomes very important.
The Chinese are not dummies. Virtually all university-educated people have studied English. Restricting their reading to scientific journals, this serves them very well. Of course, they aren't nearly as adept at writing English, but I'm often surprised to see an unedited composition that I can understand just about as well as the writing of many Americans!
Esperanto is in its heyday a hundred years ago too. I would think amongst scientist that it makes sense to switch to a easier to learn artificial language that is not national.
As I noted earlier, I can speak, understand, read and write Esperanto, and I would not recommend it for anything important because the sentences are about twice as long.
Science uses Latin and Ancient Greek over native terminology for a reason.
It's basically a matter of habit. The Greeks and Romans built the first enduring empires in Europe, and therefore their people were the first major population of scholars. Read any technical article and note the proportion of words with Greek and Roman roots. The French, who for a while were Europe's academic leaders, rather easily adopted Latin words because French descended from Latin, so many of the words already existed in their language, in more modern phonetic form.
