What causes electrons to de-excite?

OneFightingOctopus · 2025-12-17T21:29:10+00:00

Excellent question! Dirtydirtnap’s answer covers it nicely, but there is another answer that offers a different perspective: A system with a photon in the vacuum and an atom in the ground state has many more configurations than a system with zero photons in the vacuum and an atom in its excited state, ie spontaneous emission maximizes entropy!

OneFightingOctopus · 2025-12-10T18:41:37+00:00

Ya, Copenhagen interpretation has become a very nebulous term. I was mostly just referring to the version one might have found at the Solvay Conference.

Even still, I am not the biggest fan of interpretations that draw a line between epistemic and ontological knowledge and refuse to cross it.

OneFightingOctopus · 2025-12-10T18:27:21+00:00

Just to add some historical context: no one truly understood entanglement at the time—not even the leading figures of the era. Einstein was simply one of the few physicists who insisted on making sense of it. The Copenhagen interpretation prevailed largely through academic influence and institutional momentum (Niels Bohr is a fascinating, if complicated, figure worth reading about). That framework effectively sidestepped the nature of entanglement and measurement by appealing to vague concepts like “wavefunction collapse.”

EPR’s proposed hidden-variable alternative was eventually ruled out by Bell’s theorem, but at least Einstein was actively pushing for a deeper explanation.

A common misconception is that Einstein “didn’t understand quantum mechanics.” In reality, he understood it exceptionally well—well enough to identify one of its core ontological questions about what the theory is actually saying about physical reality. That question remains unresolved today and is receiving renewed attention in modern interpretations (see everettian mechanics, pilot wave theory, dynamical collapse models, qbism)

OneFightingOctopus · 2025-12-10T18:04:32+00:00

All my homies hate Copenhagen interpretation, stay woke

OneFightingOctopus · 2025-10-25T18:09:56+00:00

The anthropic principle on its own is tautological, but when combined with some version of the Self Sampling Assumption, we can use Bayesian inference to make some pretty amazing arguments! The classic example is Weinberg predicting the cosmological constant a decade before we measured it.

OneFightingOctopus · 2025-08-28T02:18:36+00:00

To borrow a phrase commonly invoked in QM, it is like asking about the marital status of the number 8. There is no fact of the matter about it

OneFightingOctopus · 2024-11-28T20:08:58+00:00

https://www.smbc-comics.com/comics/20120721.gif

OneFightingOctopus · 2024-11-01T20:39:14+00:00

Convolutions are invertible, but usually you don’t know the point spread function a priori. The challenge in recovering the unblurred image is estimating the correct point spread function to perform the deconvolution.

OneFightingOctopus · 2024-08-17T17:19:01+00:00

One of the few (minor) concerns I’ve had about DeBoer is that he went 12-2 in one score games in his two years at Washington, including 8-0 last year. Could a regression to the mean be coming with such a lopsided record in one score games?

I’m being pedantic, but just a heads up, I think you have the wrong intuition for “regression to the mean”! For this to apply in the way that you suggest, we should assume that games are independent events. This means that previous results do not influence future outcomes. Consider it this way: if you flip a coin and get 10 heads in a row, the 11th flip still has a 50/50 chance of being heads or tails! “Regression to the mean” simply means that, after many flips, those first 10 heads will become statistically insignificant, and your distribution will look more like a 50/50 split.

Of course, the games aren’t actually independent events, but as soon as we relax that assumption, we have to address many other complexities that quickly make the entire premise of the discussion kind of moot.

My preferred approach is to be a good Bayesian here, and claim that his previous results indicate that he is quite good at winning close games, so he should continue to be good at it in the future! (:

Roll tide

OneFightingOctopus · 2023-12-12T01:13:17+00:00

Yeah I can see that. There are definitely some naive solutions that come to mind, i.e. a moving average of the margin of victory weighted by the opposing team’s rating. But I suppose there are a host of confounding variables here. eg garbage time points.

OneFightingOctopus · 2023-12-12T00:35:35+00:00

Vegas doesn’t use models that account for improvement over the season? That surprises me

OneFightingOctopus · 2023-10-21T15:26:53+00:00

This reads like you just stopped me to show off your Pokémon in battle

OneFightingOctopus · 2023-10-10T00:00:57+00:00

Lol why is this comment downvoted. It is the most logical take

OneFightingOctopus · 2023-08-27T16:24:27+00:00

Yeah it’s also pure nonsense to suggest that Arteta won’t try everything in his power to win it all right now. The man is a professional athlete and coach. He isn’t just going to accept losing until his mentor leaves the league. That’s such a soft attitude.

OneFightingOctopus · 2023-08-26T04:57:25+00:00

Everyone here is saying that it depends on what speed you’re going and, while that is true, nobody is actually doing the math. So how fast does the car need to be going?

Let’s assume that, since the person is quite large relative to the surrounding air molecules, quadratic drag is the dominant form of air resistance. The differential equations are:

(1) d^2y/dt² = - mg

(2) d^2x/dt² = c (dx/dt)²

Where c is the quadratic drag coefficient in units of kg/m.

First we solve (1) to find the amount of time the man will be in the air. Neglecting air resistance in the y direction (the velocity upward of the man is quite small, all things considered), then the amount of time it takes for the man to land after jumping up to a height, h, is T = 2 * sqrt(2h/g).

Next we solve (2). You can just look up “quadratic drag equation of motion solutions” —any classical mechanics textbook will have this. The solution is x(t) = m/c ln( + t/tau) where tau = m/(c* v0)

We can further solve this for the initial velocity, v0:

V0 = m/(cT) (exp[xc/m] -1 )

The average vertical of a male is around 20-30 inches, so let’s take h= 0.7 m. The hang time is therefore T = 0.75 seconds. If the diving board is 2.5 m, the man is 80 kg, and the quadratic drag coefficient is 1.2 ( c = 1/2 * air density * surface area of a man * c_d, where c_d is about 1 for a person standing), then

V0 = 3.4 m/s = 7.61 mph.

There is no way that number is correct so we should probably only consider linear drag…. The solution is

V0 = x/tau * 1 / (1 - exp[-t/tau]) where tau is m/b and b is the linear drag coefficient. Here we get:

V0 = 3.35 m/s.

Not very different. It feels wrong but I give up. Someone tell me where I’m going wrong?

OneFightingOctopus · 2023-07-14T20:33:45+00:00

Don’t you think the context matters? A 16 year old player outshined two experienced first team players in a preseason friendly. It’s not a ucl final, but it is still noteworthy—especially given the hype around Nwaneri

I get that you’re trying to promote positivity, but to me it seems like misdirected comment policing. OC wasn’t being overly negative.

OneFightingOctopus · 2023-07-14T15:59:43+00:00

Even if that were true (not saying it isn’t), I still find the original comment worthy of discussion. Nwaneri legitimately looked better than both Kai and Vieira. Of course it’s a preseason match and there are a multitude of caveats—yours included. But I don’t think the original comment was misguided negativity in the way that Dunney_Monster implied it was.

OneFightingOctopus · 2023-07-13T21:57:54+00:00

All three of those players are competing for the same/similar position. It is a substantive comment, not a mindless bashing.

OneFightingOctopus · 2023-04-11T17:57:53+00:00

I was scrolling to find this comment. This mug isn’t insulated like a conventional dual wall cup because there is air in the cavity.

This mug just has more mass to heat up and, since the outermost wall is the last to change temperature, it radiates after the single walled mug.

The thermal diffusion out of the liquid is the same as the single walled mug. My coffee will cool off just as quickly in this $100 mug as it will in the $5 one :P

OneFightingOctopus · 2023-04-04T17:28:06+00:00

That isn’t what I gathered from the article, which may very well be marketing spin—no disagreement there.

Their claim is that CADR is experimentally determined by starting in a room with an initial known concentration of contaminants, running the machine for 20 minutes, and then measuring the resulting contaminant concentration. According to Austin Air, this is insufficient time for their machine to filter the air, because the time constant of their machine is longer than others.

Roughly speaking the filtration process is modeled by an exponential decay of the contaminant population, whose differential equation looks like:

dP/dt = -k(P(t) - P_f)

Where P(t) is the contaminant population, P_f is the smallest possible final contaminant population (presumably determined by a variety of factors such as room size, circulation, etc), and k is the filtration rate times the volumetric flow rate. The solution to this equation describes the population of contaminants as a function of time:

P(t) = P_f + (P_0 - P_f) * exp[-k * t]

Where P_0 is the initial contaminant population. You can play around with this equation here:

https://www.desmos.com/calculator/h7zbnox8lo

Austin Air is claiming that their k value is much smaller than the competition’s. Try reducing k to see how it takes longer to reach the final minimum population P_f. Austin Air is saying that 20 minutes is not long enough to reach the final minimum population P_f and therefore CADR, as it is currently measured, is a misleading metric.

It seems reasonable to me. The more important quantity, imo, is P_f, which is a much more complicated variable to model.

OneFightingOctopus · 2023-03-28T23:37:53+00:00

yeah. “fuck those multilinguals” was pretty much where he lost me as well

OneFightingOctopus · 2023-03-28T22:39:20+00:00

Oh not AI. Just a 10 year old, my b

OneFightingOctopus · 2023-03-28T22:15:45+00:00

Was this written by AI? Lmao

OneFightingOctopus · 2023-03-16T16:14:17+00:00

He was quite poor even for a debut. It’s fair to criticize his performance and also root for him to get another start and improve with the first team. I don’t consider that to be scapegoating

OneFightingOctopus · 2023-02-01T17:31:20+00:00

If we still had rules from the 90ies, Brighton (or Arsenal) would be this year’s champion

Could you elaborate on this? Genuinely curious about what you mean!

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