Even if the Polish "experiment" with the independent trade union Solidarity comes to an end, it still will have achieved the most significant changes in the history of the Soviet bloc, a Yugoslavian scholar recently returned from Poland said yesterday.

Zagorka Golubovic, former professor of sociology at Belgrade University, said the Solidarity movement has forced "a substantial change in the concept of social power in Eastern Europe." Observers recognize the independent social movement as a partner of the government in no other Soviet-bloc nation but Poland, she added.

Speaking before a small group at the Center for European Studies, Golubovic came to the United States this fall after touring Poland to spend this semester as a visiting professor at Haverford College.

Belgrade University demoted Golubovic and eight other professors in 1975 because of official displeasure with their work. Now affiliated with the university through a social sciences research center, Golubovic has helped rejuvenate Praxis, a Belgrade social sciences journal she helped found, after authorities shut it down in the mid '70s.

Hungry Enough

Poland's recent solidarity movement and the 1948 Yugoslavian drive for independence from the Soviet Union represent the two most significant cases of change within the "actually existing socialism" of the Communist world, Golubovic said yesterday.

But she added that any comparison of the two shows paradoxically that "Poland, the country that must remain in the Soviet bloc, has challenged the Soviet economic model; while Yugoslavia, the country that broke away from the bloc, has stuck with the contradictions of the Soviet model."

The Poles Golubovic visited recently seemed eager to learn from Yugoslavia's mistakes, she said, adding, "They hope to achieve a proper balance between self-adjusting markets and the central power."