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The physical properties of space may be universal, but the way people conceptualize space is not. In some groups, people tend to use egocentric space (e.g. left, right) to encode the loca- tions of objects, while in other groups, people encode the same spatial scene using allocentric space (e.g. upriver, downriver). These different spatial Frames of Reference (FoRs) character- ize the way people talk about spatial relations and the way they think about them, even when they are not using language. Al- though spatial language and spatial thinking tend to covary, the root causes of this variation are unclear. Here we propose that this variation in FoR use reflects the spatial discriminability of the relevant spatial continua. In an initial test of this proposal in a group of indigenous Bolivians, we compared FoR use across spatial axes that are known to differ in discriminabil- ity. In two non-verbal tests, participants spontaneously used different FoRs on different spatial axes: On the lateral axis, where egocentric (left-right) discrimination is difficult, their behavior was predominantly allocentric; on the sagittal axis, where egocentric (front-back) discrimination is relatively easy, their behavior was predominantly egocentric. These findings support the spatial discriminability hypothesis, which may ex- plain variation in spatial concepts not only across axes, but also across groups, between individuals, and over development. 

The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.