Comment on “Can we measure structures to a precision better than the Planck length?”, by Sabine Hossenfelder S. Doplicher * , G. Piacitelli † , L. Tomassini ‡ , S. Viaggiu § October 30, 2018 Abstract First principles do imply a non-zero minimal distance between events in spacetime, but no positive lower bound to the precision of the measure- ment of a single coordinate. Part of the literature on Noncommutative Spacetime is based on a misun- derstanding; namely, it takes as identical the following two distinct statements: 1. The localisation of a single space-time coordinate of an event cannot be performed with precision higher than the Planck Length; 2. The Euclidean distance between two events in space-time cannot be smaller than the Planck Length. The paper [1] in question does not seem to clarify this confusion. We believe, and stressed in several occasions, that the first statement is incorrect, while the second is correct; in a sense made precise in what follows. Of course, nobody can say the final word based on a reliable theory of Quan- tum Gravity; however, we can investigate what presently known and accepted first principles allow, and what they do not. We do not know any basic principle which characterises the concurrence of General Relativity and Quantum Mechanics, in a similar way as the locality principle does for Special Relativity and Quantum Mechanics [2]. But the concurrence of Classical General Relativity and Quantum Mechan- ics points to a principle of stability of spacetime against localisation of events, formulated in [3]. There Space Time Uncertainty Relations (STUR) for the * Dipartimento di Matematica, Universit` a “La Sapienza”, P.le A. Moro 5, 00185, Roma, Italy. E-mail: dopliche@mat.uniroma1.it. † SISSA, via Bonomea 265, 34136 Trieste, Italy. E-mail: gherardo@piacitelli.org. ‡ Dipartimento di Scienze, Universit`a di Chieti-Pescara G. d’Annunzio, I-65127 . E-mail: tomassini@sci.unich.it. § Dipartimento di Matematica, Universit`a “Tor Vergata”, Via della Ricerca Scientifica 1, I-00133 Roma, Italy. E-mail: viaggiu@axp.mat.uniroma2.it. 1 arXiv:1206.3067v2 [gr-qc] 20 Sep 2012