There has been in recent years a huge surge of interest in the so-called extended Wigner’s friend scenario (EWFS). In short, a series of theorems (with some variation in detail) puts pressure on the ability of different agents in the scenario to account for each of the others’ measured outcomes: the outcomes cannot be assigned single well-defined values while also satisfying other reasonable physical assumptions. These theorems have been interpreted as showing that there can be no absolute, third-person, ‘God’s eye’ description of our reality. The focus of this paper is the strongest of these no-go theorems, the ‘local friendliness’ theorem of Bong et al. (2020, Nature Physics, 16, 1199–1205), which gives earnest consideration to the possibility of a measurement that unitarily reverses an entire lab system, including a conscious agent, thereby erasing the agent’s memory. The purpose of this paper is to begin the philosophical conversation regarding key questions concerning this process: Are the events in the lab merely ‘erased’, or do they in some sense not exist at all? What would it be like to be unitarily reversed? Should an agent care about any experiences they have inside the lab before they are reversed? This analysis employs a parallel case of memory erasure, to which this case can be contrasted, arising in the context of drug-induced amnesia as a result of administering anaesthesia during medical procedures (Carbonell, 2014, Bioethics, 28(5), 245–254). I argue that the consequences of unitarily reversing an agent are much more dramatic than simply memory erasure—the set of events themselves, and the personal timeline of the agent, leave no record at all inside or outside the lab. I consider the ramifications of this for the picture of reality that arises from the EWFS.

近年来，人们对所谓的扩展 Wigner 朋友情景 （EWFS） 产生了巨大的兴趣。简而言之，一系列定理（在细节上有一些变化）对场景中不同主体解释其他每个测量结果的能力施加了压力：结果不能被分配单一的明确定义的值，同时还要满足其他合理的物理假设。这些定理被解释为表明，不可能有绝对的、第三人称的、“上帝之眼”来描述我们的现实。本文的重点是这些不合格定理中最强的，即 Bong 等人（2020 年，自然物理学，16,1199-1205）的“局部友好性”定理，该定理认真考虑了一种测量的可能性，该测量可以统一反转整个实验室系统，包括有意识的代理，从而擦除代理的记忆。本文的目的是开始关于这一过程的关键问题的哲学对话：实验室中的事件只是被“抹去”了，还是在某种意义上根本不存在？被统一反转会是什么样子？代理是否应该在逆转之前关心他们在实验室内的任何经历？该分析采用了记忆擦除的平行案例，与此案例形成对比，该案例是在医疗程序中由于施以麻醉而导致药物诱发的健忘症的背景下出现的（Carbonell，2014，生物伦理学，28（5），245-254）。我认为，统一逆转代理的后果比简单的记忆擦除要严重得多——事件本身的集合以及代理的个人时间线在实验室内外根本没有留下任何记录。 我认为这对 EWFS 产生的现实图景产生了影响。