Are Grw Tails as Bad as They Say?
نویسنده
چکیده
SUMMARY: GRW models of the physical world are severely criticized in the literature for involving wave function 'tails', the allegation being that the latter create fatal interpretive problems and even compromise standard arithmetic. I find such objections both unfair and misguided. But not all is well with the GRW approach. The complaint I articulate in this paper does not have to do with tails as such but with the specific way in which past physical structures linger forever in the total GRW wave function. I argue that this feature, which is an artifact of a particular and ultimately optional genre of collapse mechanisms, yields a total picture that is too close to the "Many Worlds" type to deserve clear methodological acceptability, particularly in light of the effective empirical equivalence between the two objectivist approaches. Presently, the most influential model of wave function reduction in foundational quantum mechanics is an appealing proposal originally introduced Over the last decade, Ghirardi and a team of collaborators have transformed this model into a detailed theory of spontaneous collapse of the wave function, making significant advances toward both a proper relativistic version and a mass-density field formulation of the theory. Although the resulting 2 approach owes much to the efforts of many additional scholars, for simplicity's sake I'll continue to refer to it as "GRW". GRW postulates a stochastic mechanism of spontaneous state reduction that operates in the position basis. In a single microscopic particle, the stochastic process is extremely weak, which makes its dynamical evolution practically indistinguishable from the one dictated by the standard linear theory (QT). The difference is that, every 10 seconds (10 years), on average, the particle's state 0 16 9 is overtaken by a sudden contraction in coordinate representation. Systems with more degrees of freedom and elementary particles develop these kicks proportionately. An ordinary laboratory pointer, for example, containing about 10 atoms, undergoes a kick every 10 seconds on average. So, what 20-4 was previously an odd and inexplicable difference of behavior between standard microscopic and macroscopic systems follows naturally from GRW dynamics. The new theory does not change the time-independent part of QT, which means that the possibility structure furnished by the standard 2 time-independent algorithm is preserved. GRW is encouragingly agreeable from an objectivist point of view. Its fundamental dynamics is free of inauspicious references to consciousness or measurement; its portrayal of the ordinary macroscopic world tells us …
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