SIMULTANEOUS press conferences were held last week in Washington, Paris, London and Geneva announcing a refusal to engage in scientific cooperation with the Soviet Union by 7,900 prominent scientists from 44 nations. The scientists were protesting the continued jailing and internal exile of such Soviet scientists as Anatoly Scharansky, Yuri Orlov, Andrei Sakharov and others.

The scientists pledged not to visit the Soviet Union or to welcome Soviet scientists and engineers to their own laboratories at least until after next month's international review of the Helsinki Accords. Linkage of the moratorium with the Helsinki review conference will almost certainly have no effect on Soviet policy, but the withdrawal from cooperative efforts itself is an immensely powerful weapon.

Whether the Soviet Union intends to continue to expand economic and technological cooperation with the West, or whether it eventually chooses to try to go it alone, a measure of scientific freedom -- including the free exchange of information, travel by Russian scientists abroad, and some freedom of expression at home -- is a must for any scientific excellence they aspire to. Modern science is an international enterprise, and no national group can remain at the frontier for very long without constant dealings with colleagues abroad.

Until a year or two ago, scientists -- especially some American scientists -- ignored flagrant repression of the freedoms of Soviet scientists in the hope that better relations with the United States would gradually relax Soviet policy. But (predictably) distinguished Soviet scientists invited to address international conferences would be replaced at the last minute by party hacks. Foreign scientific journals were (and are) regularly censored. Soviet scientists have routinely declined to share data in bilateral and international technical exchanges. All this was more or less disregarded, and the Soviet Union was permitted both the scientific cooperation it wanted and whatever policies it chose to pursue at home.

The sentencing of physicist Yuri Orlov -- chairman of a group monitoring Soviet compliance with the Helsinki Accords -- to seven years in a strict regime labor camp and five years of internal exile, marked the beginning of a change. More than 40 other members of the Soviet Helsinki Watch Groups -- many of them scientists and engineers -- have since followed Mr. Orlov into prison or exile, and scientists in growing numbers around the world are now saying they've had enough.

A recent meeting of physicists in France issued "anti-invitations" to their Russian colleagues, explaining that it was impossible to issue the normal invitations with so many Russian physicists in prison. Because of Mr. Sakharov's exile, a famous American surgeon has publicly renounced awards made to him by a Soviet scientific society. A collaborative project at an international physics center in Switzerland had to be canceled when key staff members refused to take part.

These kinds of protests are heard in the Soviet Union -- not only by the government, but also, despite the Kremlin's best efforts, by individual scientists. They have a special force precisely because they are not linked to any government's policy, but represent the acts of individuals speaking for themselves. The scientists' protests are the authentic voice of conscience -- it is good that Soviet authorities are being compelled to listen to it.