Linkages between astronomy and physics have always been intimately close and mutually stimulating. Most often it was physics that served astronomy with its explanatory power. Today, however, we are increasingly witnessing the reverse: astrophysical considerations are being used to constrain new physics and moreover they are more efficient than laboratory experiments. This contribution reviews the ways helio- and white dwarf asteroseismology – branches in which Wojtek Dziembowski played a prominent role – are used for this purpose.