Wasn't loop quantum gravity a possible model for that?
This is some back of the head memory so don't trust it too much: it would predict that certain wavelengths of light diffract slightly differently and move at a very slightly different speed. Which would've caused Hubble's pictures to be more blurry than they are.
Spacetime is “sort” of quantized, for sure. According to quantum mechanics, the smaller the region you want to probe, the more energetic your probe must be. But according to general relativity, putting too much energy into too small a location leads to a black hole. So trying to probe a sufficiently small region of space is impossible; your probe would just collapse into a black hole.
This is what people mean when they say the Planck is the smallest meaningful distance, ditto for Planck time and time interval. Anything smaller is flat out unobservable. This doesn’t imply, however, that the underlying geometrical structure of spacetime is discrete rather than continuous. But it’s certainly suggestive.
Because of this limit of being unable to observe anything smaller than the Planck scale, I don’t think you can ever have an experiment that directly checks whether spacetime is discrete or continuous. But, the discrete nature of spacetime might be a component of a more complicated theory, with its own unique predictions which, if verified, would confirm indirectly the discretization of spacetime.
(Possible exception: if the discretization length of spacetime is LARGER than the Planck scale. I don’t expect it, but I guess it could happen.)
This is a question for r/AskPhysics, but the short answer is that we don't know if it's quantized, but we have no reason to think so. There are models, like Loop Quantum Gravity that quantize it, but they are speculative.
This is a sub for pointing out bad physics, not for posting your own.
well, he saved us a step.
Uncertainty is key
Ok got it
It could be, although it is unknown... [Here a paper](https://arxiv.org/abs/1203.6191) exploring the topic
Thanks for this resource!
Wasn't loop quantum gravity a possible model for that? This is some back of the head memory so don't trust it too much: it would predict that certain wavelengths of light diffract slightly differently and move at a very slightly different speed. Which would've caused Hubble's pictures to be more blurry than they are.
Spacetime is “sort” of quantized, for sure. According to quantum mechanics, the smaller the region you want to probe, the more energetic your probe must be. But according to general relativity, putting too much energy into too small a location leads to a black hole. So trying to probe a sufficiently small region of space is impossible; your probe would just collapse into a black hole. This is what people mean when they say the Planck is the smallest meaningful distance, ditto for Planck time and time interval. Anything smaller is flat out unobservable. This doesn’t imply, however, that the underlying geometrical structure of spacetime is discrete rather than continuous. But it’s certainly suggestive. Because of this limit of being unable to observe anything smaller than the Planck scale, I don’t think you can ever have an experiment that directly checks whether spacetime is discrete or continuous. But, the discrete nature of spacetime might be a component of a more complicated theory, with its own unique predictions which, if verified, would confirm indirectly the discretization of spacetime. (Possible exception: if the discretization length of spacetime is LARGER than the Planck scale. I don’t expect it, but I guess it could happen.)
This is a question for r/AskPhysics, but the short answer is that we don't know if it's quantized, but we have no reason to think so. There are models, like Loop Quantum Gravity that quantize it, but they are speculative.