Is it okay to use different tenses in this way?
Try to find an area where science isn't needed, where experiments weren't perfomed.
Is it okay to use different tenses in this way?
Try to find an area where science isn't needed, where experiments weren't perfomed.
You can also say the whole sentence in present tense: "Try to find an area where science isn't needed, where experiments aren't perfomed." to keep the consistency. Although your version is just fine too.
Certainly two different tenses is perfectly fine, and in fact, changing the second to present tense, as was suggested, would completely change it's meaning. As written, the implication is there are areas where experiments were simply not performed. If you change this to aren't performed, it implies that as a rule, experiments are not performed in this area.