Why can’t we get smaller than the plank length?
In: Physics
Not really sure what you mean by “get smaller than” but if you mean “why is the plank length considered the smallest possible (physical size) unit of anything?” then the answer is two-fold. One – our understanding of physics stops at the plank length – anything smaller just doesn’t “work” in our formulae. Two – to measure something (anything at all), we need to detect it. We detect things by bouncing particles off them (e.g., we see a car because photons bounce off the car and strike our retinas in the back of our eyes). To see/detect smaller and smaller things, we need to use more energetic particles. This is because more energetic particles have smaller wavelengths, and we cannot detect things smaller than the wavelength of whatever we’re using for detection. The plank length comes into play because if we try to detect something smaller than the plank length, we need to use particles so energetic that they will become black holes (mini black holes, but black holes nonetheless). That is, cramming that much energy into that small a space causes gravitational collapse, which means no detection at that scale is possible.
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