  If (as portrayed above) the spontaneous localization of particles were to a precise position, i.e., to the position corresponding to the outcome ‘up’ or the outcome ‘down,’ the GRW collapse models would successfully resolve the measurement problem. Technically speaking, a precise localization is achieved by multiplying |ψ7&gt; by a delta function centered on the position corresponding to either the outcome ‘up’ or the outcome ‘down’ (see the entry on collapse theories, section 5 and Albert 1992, chapter 5); where the probability of each of these mutually exhaustive possibilities is ½. The problem is that it follows from the uncertainty principle (see the entry on the uncertainty principle) that in such localizations the momenta and the energies of the localized particles would be totally uncertain, so that gases may spontaneously heat up and electrons may be knocked out of their orbits, in contradiction to our experience. To avoid this kind of problems, GRW postulated that spontaneous localizations are characterized by multiplications by Gaussians that are centered around certain positions, e.g. the position corresponding to either the outcome ‘up’ or the outcome ‘down’ in the state |ψ7&gt;. This may be problematic, because in either case the state of the L-apparatus pointer at (what we characteristically conceive as) the end of the L-measurement would be a superposition of the positions ‘up’ and ‘down.’ For although this superposition ‘concentrates’ on either the outcome ‘up’ or the outcome ‘down’ (i.e.,  the peak of the wave function that corresponds to this state concentrates on one of these positions), it also has ‘tails’ that go everywhere: The state of the L-apparatus is a superposition of an infinite number of different positions. Thus, it follows from the eigenstate-eigenvalue link that the position observable of the L-apparatus has no definite value at the end of the measurement.  But if the position observable having a definite value is indeed required in order for the L-apparatus to have a definite location, then the pointer will point to neither ‘up’ nor ‘down,’ and the GRW collapse models will fail to reproduce the classical-like behavior of such  systems.[11]