标题： 关于Salecker-Wigner极限及在时空泡沫研究中使用干涉仪 显示英文标题

标题： On the Salecker-Wigner limit and the use of interferometers in space-time-foam studies

摘要： 最近的论文gr-qc/9909017批评了Salecker和Wigner在1950年代得出的距离可测量性限制。 如果这一批评得到证实，将对所有以各种方式使用著名的Salecker-Wigner结果的近期研究产生重要影响，但我在这里表明，gr-qc/9909017中报告的分析是错误的。 与Salecker和Wigner寻求适用于普朗克尺度的操作性距离定义不同，gr-qc/9909017的分析依赖于一些在大多数当前实验背景下看似自然的假设，但在普朗克尺度下甚至没有意义。 此外，与gr-qc/9909017中的声明相反，在Salecker-Wigner推导中使用的相关量子不确定性无法真正消除；不出所料，它只能与其他类似贡献进行交换，从而增加测量的总不确定性。 我还会评论Salecker-Wigner极限在我最近提出的基于干涉仪的检验时空量子性质的方案中所起的作用，该方案在gr-qc/9909017中被错误描述。 特别是，我强调如gr-qc/9903080中详细讨论的那样，只有部分可以利用现代干涉仪探测的量子引力观点是由Salecker-Wigner极限所激发的。 从这种干涉测量研究中我们可以期望获得的主要见解涉及“泡沫”模型的时空属性，这些模型本身具有内在的重要性，而不论Salecker-Wigner极限如何。 显示英文摘要

摘要： The recent paper gr-qc/9909017 criticizes the limit on the measurability of distances that was derived by Salecker and Wigner in the 1950s. If justified, this criticism would have important implications for all the recent studies that have used in various ways the celebrated Salecker-Wigner result, but I show here that the analysis reported in gr-qc/9909017 is incorrect. Whereas Salecker and Wigner sought an operative definition of distances suitable for the Planck regime, the analysis in gr-qc/9909017 relies on several assumptions that appear to be natural in the context of most present-day experiments but are not even meaningful in the Planck regime. Moreover, contrary to the claim made in gr-qc/9909017, a relevant quantum uncertainty which is used in the Salecker-Wigner derivation cannot be truly eliminated; unsurprisingly, it can only be traded for another comparable contribution to the total uncertainty in the measurement. I also comment on the role played by the Salecker-Wigner limit in my recent proposal of interferometry-based tests of quantum properties of space-time, which was incorrectly described in gr-qc/9909017. In particular, I emphasize that, as discussed in detail in gr-qc/9903080, only some of the quantum-gravity ideas that can be probed with modern interferometers are motivated by the Salecker-Wigner limit. The bulk of the insight we can expect from such interferometric studies concerns the properties of "foamy" models of space-time, which are intrinsically interesting independently of the Salecker-Wigner limit.