71–80 of 86 posts
Stop posting physics articles on hacker news. Just because everyone here has watched too much Star Trek and Star Wars doesn't mean we actually understand a single solitary shred of this stuff...although it sounds cool.
Reading is how you learn.
Earlier quoted context omitted.
"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…
As someone who hasn't studied this (yet) does that mean that the reason protons and electrons don't annihilate is because their Baryon Number wouldn't sum up to zero? (With Protons having 1 and Electrons 0 if I understood correctly)
But baryon number conservation is an asserted symmetry and there is no fundamental reason it holds. Finding proton decay would demonstrate that it does not but so far there is no evidence that protons (or bound neutrons) spontaneously decay.
Earlier quoted context omitted.
Right. Science uses the word "theory" in the same sense as music theory. A scientific theory is a collection of related ideas that form a robustly cohesive whole, with the power to explain some set of phenomena.
Theory literlly means observation in ancient greek, look it up
Earlier quoted context omitted.
"Falling into the nucleus", as stated in that Stack Exchange question, is a classical (as in "wrong" :) ) way to look at it. The 1s orbital of the electron is spherically symmetric, with non-zero probability of the electron being right in the center of the atom (so within the nucleus), and decreasing probability of it being farther away. So e.g. a good approximation of the He atom is of two neutrons, two protons, and…
As someone who hasn't studied this (yet) does that mean that the reason protons and electrons don't annihilate is because their Baryon Number wouldn't sum up to zero? (With Protons having 1 and Electrons 0 if I understood correctly)
If you start with a proton and an electron, you have 3 quarks and 1 lepton, so whatever the interaction you have to end up with 3 quarks and 1 lepton (plus any number of quark-antiquark and lepton-antilepton pairs). E.g. for beta decay:
neutron (3 quarks) -> proton (3 quarks) + electron (lepton) + antineutrino (antilepton)
> Antihydrogen is made by mixing plasmas of about 90,000 antiprotons from the Antiproton Decelerator with positrons, resulting in the production of about 25,000 antihydrogen atoms per attempt. Antihydrogen atoms can be trapped if they are moving slowly enough when they are created. Using a new technique in which the collaboration stacks anti-atoms resulting from two successive mixing cycles, it is possible to trap on…
If you enjoyed that, you may also enjoy the discussions of how people synthesize super heavy elements, such as in this video: https://www.youtube.com/watch?v=z3oY-XHwss8 Superheavy elements even beat antihydrogen on this scale; one of the ones recently named was confirmed to have been synthesized based on only three atoms!
Earlier quoted context omitted.
> At the end of the day, there are interactions that are seen in Nature and interactions that aren't. That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.
I'm very interested in seeing that proof.
https://en.wikipedia.org/wiki/Reversible_reaction
Assuming you do not outright lose some reactants from the system, the reverse reaction is still occurring. However, because the reaction constant is so small, the resulting product is highly probable to essentially immediately undergo the forward reaction. However, it will still be present in some equilibrium - just an incredibly low one, in the ratio of the reaction rate coefficients. You'll have 10^14 times as much of the forward reaction, or whatever.
Earlier quoted context omitted.
> At the end of the day, there are interactions that are seen in Nature and interactions that aren't. That's provably false. Every reaction occurs in nature, even the vanishingly improbable ones, just at an extremely low reaction coefficient. They're still there, just at a probability of 10^-14 or whatever.
What? There are interactions that can never occur because they're forbidden by the laws of physics - you'll never violate conservation of [energy, baryon number, momentum, etc.] even with probability 10^-14.
But if the reaction is the least bit reversible (and most are) then the reverse reaction is still proceeding even though the forward reaction is stronger. It's just doing so at an incredibly low rate, and the products are likely to be immediately converted by the forward reaction.
You are looking at averages and claiming they hold for every single event in a stochastic simulation. Taking the example of entropy - it's not impossible that entropy decreases in a system, it's just less likely than it increasing. On a stochastic level, entropy decreases all the time, it's just that on average it increases more than it decreases.
Reactions work the same way. You're not actually making chemicals react as a singular act, you're creating a forward reaction that occurs more rapidly than the reverse reaction.
If we had a hypothetical chemical Maxwell's Demon - you could "bottle" up the tiny bits of those outputs from the reverse reaction before they underwent the forward reaction again.
Earlier quoted context omitted.
What? There are interactions that can never occur because they're forbidden by the laws of physics - you'll never violate conservation of [energy, baryon number, momentum, etc.] even with probability 10^-14.
Sure, technically correct is the best kind of correct I suppose. But if the reaction is the least bit reversible (and most are) then the reverse reaction is still proceeding even though the forward reaction is stronger. It's just doing so at an incredibly low rate, and the products are likely to be immediately converted by the forward reaction. You are looking at averages and claiming they hold for every single event…
For example particle accelerators can shoot particles against some target one by one, and so there's no need to look at averages. Some interactions never occur, to the best of our measuring ability (i.e. highest energies and number of repetitions). Some others are right away forbidden by laws much stronger than entropy in thermodynamics, in the sense that they're not averages, but mathematical derivations off the symmetries of the universe.
Earlier quoted context omitted.
I'm very interested in seeing that proof.
> The concentrations of reactants and products in an equilibrium mixture are determined by the analytical concentrations of the reagents (A and B or C and D) and the equilibrium constant, K. The magnitude of the equilibrium constant depends on the Gibbs free energy change for the reaction.[2] So, when the free energy change is large (more than about 30 kJ mol−1), then the equilibrium constant is large (log K > 3) and…
If you look at the micro scale, though, and instead of having a soup of molecules you deal with single molecules, whether a reaction is possible or not isn't a probabilistic thing anymore. The energies your molecules have are actual numbers, and if they don't add up, you won't have a reaction.
Earlier quoted context omitted.
If you enjoyed that, you may also enjoy the discussions of how people synthesize super heavy elements, such as in this video: https://www.youtube.com/watch?v=z3oY-XHwss8 Superheavy elements even beat antihydrogen on this scale; one of the ones recently named was confirmed to have been synthesized based on only three atoms!
Yes, it's amazing work. Also, don't be fooled that because it is so difficult to produce today that it can't be scaled immensely. Plutonium production was scaled from nanogram levels to ton levels in less than a decade.
If we scale up production in the next decade at the same pace you're describing, we might get to nanogram levels.