I need help, please, in understanding two extreme but quite different situations, say 1 and 2 below: 1. Suppose that an observer falls freely and radially towards a neutron star. As he approaches the star he will begin to detect, by observing test particles in his local inertial frame (set up far from the star), increasingly more apparent tidal phenomena. For instance test particles he releases from rest along a line through the centre of the star will be measured to accelerate and separate from each other. In fact this observation must lead him to conclude that his inertial frame is getting too big for its boots, as it were, and that he must restrict it to a volume in which such tidal phenomena remain imperceptible. The extent of a local inertial frame is of course subjective and depends on circumstances. Setting aside this caveat, the observer will find that if he ties the particles together with string before releasing them, the string will eventually break. This he will attribute to a tidal force, if he adopts a Newtonian perspective instead of explaining such phenomena in terms of the Schwartzchild metric. 2. Consider the same observer (somehow surviving) in an inflating flat FRW universe that begins to expand exponentially rapidly after he has set up his local inertial frame. Suppose he again releases two test particles from rest in this frame. What happens as the scale factor, and its derivatives with respect to time, change exponentially with time? Am I correct in assuming that nothing at all happens, and that his local inertial frame, with its test particles at rest, remains undisturbed despite the extreme "stretching of space" that takes place everywhere as his universe inflates? (I believe that this is the view taken by cosmologists.) Or am I wrong, and will a string connecting these particles break?