1) Time slows-down in strong gravity field. But I cannot understand for whom (in which reference frame)
What about the paradox that time stops for an observer at earth who thus would never see the traveller disappear behind blackhole horizon. But I think that strong gravity happens around the traveller, so it is the traveller whose time shall stop! And for earth observer time is never changed b/x gravity around the observer never changes.
2) And is there time inside black-hole if time stops at the horizon - also in which reference frame we have this problem? If time stops at horizon in one reference frame than we have this problem only in this reference frame.