Jacobs focuses on the Planck length scale; and practice usually focuses on the Planck energy scale. Interestingely, one can also consider the Planck mass, as it has been done more recently. Naively, one would not expect some difference here. But then again the Planck mass stands out because its value is as such much closer to known regimes:
\begin{quote} Puzzling is the fact that | unlike Planck length and Planck energy, mPlanck falls within a very reachable physical domain: micrograms. It has long been hard to see what sort of quantum gravity effect can happen at the scale of the weight of a human hair. \end{quote}
Can the Planck mass be behind a whole avenue of quantum phenomenology that challenges that quantum effects can only be relevant at unreachable scales? As Huggett et al., write, indeed so:
\begin{quote} According to lore in the philosophy of QG, the problem of quantum gravity is (very nearly) purely one for the theoreticians. It is just too difficult to hope for discriminating signatures of QG in data, because the relevant empirical regimes far exceed our capacities for experimentation (in high energy physics) or direct detection (in astrophysics and cosmology). But this lore is misleading of fundamental physics practice today. In recent decades, and to wide acclaim in the surrounding discipline, a range of empirical testing strategies have been pursued within the arena of quantum gravity phenomenology, as proposed means of gaining significant, increased empirical traction on the problem of QG. \end{quote}
However, as also stressed by Huggett, Linnemann and Schneider, the case is more intricate than you would think. Depending on the paradigm one finds oneself in, one will either see the gravitationally-induced entanglement experiments that work at the relevant mass Planck length — provided the right outcome — as providing evidence about the quantum nature of gravity or not. These are paradigms in so far as that the decisive assumptions at play cannot be decided between based on rational arguments; it requires a push whether to think in one or the other but no specific argument seems to prefer one over the other
But what kind of paradigm could it be that suddenly the Planck mass comes into focus with no corresponding Planck length or energy. (Something a bit lighter than a hair could be a Planck mass — but without being of the Planck length or measured with Planck energy — how can it relevant for QG? Note that already Planck length and momentum have not immediately the same interpretations: length directly pertains to the object (at least naively); energy is meant to describe the energy of light needed to measure out that very object. So in that sense it is not odd if mass is some distinct property again.)
\begin{quote} Puzzling is the fact that | unlike Planck length and Planck energy, mPlanck falls within a very reachable physical domain: micrograms. It has long been hard to see what sort of quantum gravity effect can happen at the scale of the weight of a human hair. \end{quote}
Can the Planck mass be behind a whole avenue of quantum phenomenology that challenges that quantum effects can only be relevant at unreachable scales? As Huggett et al., write, indeed so:
\begin{quote} According to lore in the philosophy of QG, the problem of quantum gravity is (very nearly) purely one for the theoreticians. It is just too difficult to hope for discriminating signatures of QG in data, because the relevant empirical regimes far exceed our capacities for experimentation (in high energy physics) or direct detection (in astrophysics and cosmology). But this lore is misleading of fundamental physics practice today. In recent decades, and to wide acclaim in the surrounding discipline, a range of empirical testing strategies have been pursued within the arena of quantum gravity phenomenology, as proposed means of gaining significant, increased empirical traction on the problem of QG. \end{quote}
However, as also stressed by Huggett, Linnemann and Schneider, the case is more intricate than you would think. Depending on the paradigm one finds oneself in, one will either see the gravitationally-induced entanglement experiments that work at the relevant mass Planck length — provided the right outcome — as providing evidence about the quantum nature of gravity or not. These are paradigms in so far as that the decisive assumptions at play cannot be decided between based on rational arguments; it requires a push whether to think in one or the other but no specific argument seems to prefer one over the other
But what kind of paradigm could it be that suddenly the Planck mass comes into focus with no corresponding Planck length or energy. (Something a bit lighter than a hair could be a Planck mass — but without being of the Planck length or measured with Planck energy — how can it relevant for QG? Note that already Planck length and momentum have not immediately the same interpretations: length directly pertains to the object (at least naively); energy is meant to describe the energy of light needed to measure out that very object. So in that sense it is not odd if mass is some distinct property again.)