May / Might

"May" expresses possibility, permission, or human interpretation. "Might" is used in the same way, but implies possibility over permission:

This outcrop may be studied. (Implies that permission has been given.)

This outcrop might be studied. (Implies that the possibility merely exists.)

Many writers puzzle between "may" and "can," and I always advise them to elect "may" when human permission or human interpretation (especially speculation) is involved, and "can" when the point is more factual or proven:

The calculated R2 value of 0.68 demonstrates that a relationship may exist between silica concentration and the presence of iron. (Human speculation is involved.)

Tests show that dust particles produced by breakage can carry elementary electrostatic charges. (The statement is more factual and proven than interpretive.)