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Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema?
If the latter, how do you even define the notion of diameter?
I think in some areas of physics, such as high-energy physics, there is not much left to discover. The Standard Model works. What branches of physics are likely to see progress?
But see https://en.wikipedia.org/wiki/List_of_unsolved_problems_in_p...
I think in some areas of physics, such as high-energy physics, there is not much left to discover. The Standard Model works. What branches of physics are likely to see progress?
Someone please help correct my intuition here: the harder it is to find flaws in the Standard Model, the harder it would be to use such new physics in engineering. Basically I'm curious whether continuing failures to find new physics can be taken as evidence that, if and when we find the new physics, it will be very difficult to apply. I'm not against science for its own sake, however. Just more of an engineer than a…
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
I suppose you have to pick a probability criteria for the diameter.
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
This paper[0] says that it is defined in terms of a "probability amplitude that an interaction between a photon of four-momentum q^μ (Q2=−q2) and a charged constituent of the proton can absorb such a momentum with the proton remaining in its ground state." So, not exactly a radius, but "radius" is an okay conceptual mnemonic.
I think in some areas of physics, such as high-energy physics, there is not much left to discover. The Standard Model works. What branches of physics are likely to see progress?
There's still physics in every successive new digit of the physical constants. The gravitational constant is only known to roughly 5 digits. Get to work!
Albert A. Michelson, 1894, just 11 years before Einstein first published about special relativity.
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
The definition is somewhat arbitrary, but still has some real physical significance. In actual fact, a proton is a field, so it doesn't have sharp boundaries. But the amplitude of the field still dies off very rapidly with distance from the center, so you can pick some arbitrary small value and say "the point at which the amplitude becomes less than this value is the radius of the proton". What matters is not really the number that you get out of this, but the fact that the experimental results of measuring this value appeared to change in the presence of muons. This was a phenomenon that was not predicted by present theory, and if it had held up, would have been a major breakthrough. One of the biggest problems in physics right now is that there are no experiments (except possibly this one) whose results are at odds with the Standard Model. That makes it hard to improve the model!
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?
> an electron [...] spends part of its time inside the proton (which is a constellation of elementary particles called quarks and gluons, with a lot of empty space).
I wish a physicist could explain here how the very notion of "diameter" has any meaning for an object whose size (IIUC) belong entirely to the quantum realm. Is the hydrogen atom two hard little balls of matter orbiting one another, as we were taught in primary school, or are they a probabilistic soup with various, vaguely localized extrema? If the latter, how do you even define the notion of diameter?