I just came across this article, provacatively titled "Dumber in English". What the author, Stefan Klein, really means is "Dumber In Your Second Language", and he's almost certainly right about that.
I know that when I was doing my post-doc in Germany, I was significantly less nimble in German. I didn't have much practice in the language, and that meant a lot of mental overhead while using it. I never became truly comfortable with it, although I did get better. The throbbing headaches stopped after a few weeks, for example, which was certainly a visible and welcome sign of improvement. After a I started to dream in the language (and once in a great while I still do, with progressively less impressive fluency). I knew that I was really learning the stuff when I dropped a piece of apfelkuchen into a mud puddle, and reflexively swore in German. (Not to fear, the cake was in a paper bag, and was recoverable with quick action).
Scientifically, I was working under a handicap, and I knew it. My secret weapon, though, was the way the chemical literature was (and is) largely written in English. But this is a particularly painful thing for Germans, since their language was once on top of the heap in chemistry, physics, and several other sciences as well. Reading Klein's description of a recent conference in his native country, you can feel it:
". . .All the speakers – six Germans, plus three from the United States and one from Great Britain – were outstanding. And they all spoke either English or, in the case of a German speaker, now and then something similar. Unusual word-choices and serpentine sentences can make a speech seem more brilliant than it actually is.
But who in the audience spoke English? No one. And even the four foreign guest speakers could easily have understood a lecture in German, because simultaneous translation was available over headsets that were readily on hand. As someone from the sponsoring foundation told me, of course it would be better if the local guests would simply speak German. This would increase the public resonance. But the professors had another idea. Their argument: People only take a conference seriously when English is the official language. . ."
He brings up the historical practice of scholarly Latin, and how this dissolved in the 16th and 17th centuries as thinkers began to write in the vernacular. (This, though, actually hindered the flow of information, as far as I can see - a lingua franca isn't such a bad thing). He also worries that science will come to be even more separated from the general run of the population in non-English speaking countries, but I'm not so sure. Most native English speakers don't have much of a connection with the subject, despite every linguistic advantage. There's also the problem of whether some languages will cease to develop their scientific vocabularies, preferring the English terms out of convenience. As far as I can tell, this is already happening - mind you, English borrows terms from the other languages as well, although not to the same extent.
Klein also brings out some examples of concepts that he feels come across better in their original German than in translation. but here I'm not so convinced. Einstein's complaint about "spukhafte Fernwirkung", to pick one, is generally rendered into English as "spooky action at a distance", which seems to me to get the concept across very well, as opposed to Klein's clunky "long distance ghostly effect". There are definitely things that don't translate well from German to English (and across any other language pair you can name), but this isn't one of them.
I don't see anything stopping the rise and dominance of English in the sciences (and to be sure, neither does Klein). I realize that I write from the perspective of a native English speaker, and having had to live in another tongue, I can sympathize with those who have to come to grips with the language. (Especially our ridiculous spelling, although I'll vote for that over German grammar any day of the week). To my mind, the advantages of being able to speak the same language, however roughly, outweigh the problems of a scientific tower of Babel.