score:33
The policies very much varied with time.
Even more they differed between scientific institutions in USSR.
First of all, there was always scientific exchange through publications. Until the middle of 1930s Soviets could publish papers in Soviet journals in foreign languages. Later this was prohibited and publication abroad strongly discouraged. But since 1960s many Soviet journals in exact sciences were translated into English.
Kolmogorov wrote his main book on probability in German. His later works were translated.
In 1920s some Soviet mathematics could travel abroad. This was later very much restricted but foreign travel never stopped completely. Kolmogorov was able to travel most of the time, except some especially dark period since the late 1930-s to 1960s.
Foreign scientists could travel to Soviet Union. Again, the ease and frequency of these travels very much changed with time over the period of Soviet rule.
Finally your conjecture that there was more international contacts in "harmless areas" such as humanities, is completely wrong. It was just the opposite: there was more contacts in physics and mathematics, less in chemistry and biology, and almost NONE in humanities. Because the Soviet rulers considered humanities the most dangerous area through which "ideological influence" could penetrate. On the other hand Soviet work in humanities was valued much less in the West, they did not care to translate journals etc. The reason is that Communist authorities controlled humanities in a much stricter way than sciences. Of sciences they interfered most to biology and less of all in mathematics. "Marxist philosophy" was the justification of the power of the regime, and "ideological purity" was guarded more vigilantly then the atom bomb "secrets" (which were stolen from the West anyway).
Finally on point 2. 99% of those who traveled or could meet foreign visitors lived and worked in the few institutions in Moscow with special status. The rest of Soviet Union was practically isolated from all foreign contacts, except that some scientific literature was available to us and some of our publications were translated abroad.
For example, I worked in Ukraine in 1976-90. Until 1987, I was NEVER permitted to travel abroad, though I had many invitations. And I have never seen a single live foreign mathematician, except one person from GDR who studied in Soviet Union! But some people based in Moscow at this time traveled and invited foreign visitors frequently.
Upvote:4
To partially complement some of the other answers, let me mention the existence of Mir Publishers. Lots of titles mentioned here.
When I was a math undergrad in Argentina, in the 1980s, we would all buy the Soviet textbooks because they were the cheapest. Also, they were in Spanish, which was preferable for many students who lacked enough command of English. Many examples here; I seem to recall others that are not in this list.
Finally, here is an example of a textbook by Kolmogorov himself, translated and published in the US in the 1970s.
Upvote:6
To publish any material in a foreign journal or present a report on international conference, Soviet authors would have to get an approval from a special clearance department that existed in every educational and scientific institution (universities, research institutes, etc.) You would bring your paper to this department and their goal was to see if you are disclosing any top secrets, patented technologies, know-hows or trying to portray the Soviet government in a bad way. If anything was not to their liking, you would be asked to re-write it. The same process would be implemented with foreign correspondence. Imagine you are working in a modern company that manages high volumes of extremely sensitive data. Any incoming or outcoming traffic would be scanned and filtered. Now imagine something similar but on grander scale and in an analog world - that's what it looked like from the inside of USSR. Plus add the fact that most Soviet schools taught German and French as foreign languages while English became dominant only in the 1980s.
Upvote:13
It depends a lot on timing, but I can make some general comments. (I got my PhD in theoretical chemistry in 1976, so I've been following this to some extent since the late 60s.)
First, there is a huge, sharp, big distinction between military research and everything else. Most military stuff is classified and both sides tried their best to keep that from getting loose. They still do. (This is mostly on the engineering side of things rather than basic research.) In fact, even nominally allied states mostly try to keep their secrets secret.
For American scientists for non-military research for most of the time from the 40s to the 70s, language and logistics was more of a barrier than policy. Academic journals from both sides were acquired -- usually by subscription -- and were sort-of available. I say "sort of" because in those long-gone days a copy of a Russian journal in a library in Boston, say, was not at all available to an academic in Minnesota or even New York City. There was no Internet and hard copy was hard copy and you pretty much had to visit a library which carried the journal to read the papers. (You could request interlibrary loan if you knew a paper existed, but mostly you didn't bother. Library research is hard enough when the journal right down the hall.)
And the Russians were so uncouth as to write their papers in Russian! Which few academics in the US knew.
Starting in the 50s the military funded a program of translating key Russian journals and publishing an English edition, and those were reasonably available, but it only covered a select set of the top journals. I looked at some occasionally, but they were never very helpful, in part because the two scientific cultures had developed is partial isolation and even if the words were English, a Russian journal would be enough different to be markedly harder to use.)
The bottom line is that as far as journals went, most American scientists did not have access because they didn't know Russian and didn't have convenient access to copies of the journal.
Academic travel existed, but was fraught, though it started to loosen in the 70s. American scientists who had a security clearance or thought they might want one mostly didn't travel to Eastern Europe except on official business. Others might have, but it was moderately expensive and fairly inconvenient. (My own PhD advisor was of 100% Russian descent (3rd generation and could at least swear in Russian) but never went further east than Sweden.)
Military-related research aside, contact was sclerotic, but this was not so much a direct policy of the government as a side-effect of other policies and things like language differences.
(I can't say much useful about the period before WW II.)