## Posts

Comment by hwold on An Untrollable Mathematician Illustrated · 2018-04-13T07:49:51.076Z · score: 8 (2 votes) · LW · GW

I don’t understand where that 1/2 comes from. Unless I have made a gross mistake P(A|A => B) < P(A) even if P(A&B) > P(A&not(B)). In your first example, if I swap P(AB) and P(A&not(B)) so that P(AB) = .5 and P(A&not(B))=.3 then P(A|A=>B) = .5/.7 ~ 0.71 < 0.8 = P(A).

Comment by hwold on Open thread, May 22 - May 28, 2017 · 2017-05-29T08:56:49.323Z · score: 0 (0 votes) · LW · GW

You’re right, the 2^(-3/4) (and the 2^1/4) is probably quantitatively wrong (unless each side is perfectly heat-conducing but both are isolated from each other. Or if the planet is a coin facing the sun. You know, spherical cows in a vacuum…). But I don’t think that changes the qualitative conclusion, which hold as long as the bright side is hotter but not twice as hotter than the perfectly-heat-conducing planet.

Comment by hwold on Open thread, May 22 - May 28, 2017 · 2017-05-29T08:41:20.547Z · score: 0 (0 votes) · LW · GW

Given perfect conduction (uniform surface temperature, bright side and dark side have the same temperature at all times), https://en.wikipedia.org/wiki/Black-body_radiation#Temperature_relation_between_a_planet_and_its_star applies : temperature does not depend on rotation speed. Then T = T_sun sqrt(R_sun/(2D)) ; it is the temperature T that balance incoming radiation P_inc = pi (R_planet^2) (R_sun^2) (T_sun^4)/(D^2) and emitted radiation P_em = 4 pi (R_planet^2) * T^4

Let's suppose no conduction at all. The bright side and the dark side does not exchange heat at all. Let's take two limiting cases : tide-locked planet, and an "infinitely fast" fliping planet.

In the first case, the dark side of the planet is at absolute 0. The bright side of the planet receives the same incoming radiation but emit half its radiation (halved surface) -- change 4 pi to 2 pi in P_em. Its temperature is T_bright = 2^(1/4) T. Average temperature of the planet is (0+T_bright)/2=2^(-3/4) T

In the second case, each side gets half the incoming power from the sun and radiates half the energy (surface halved). Average surface temperature of the planet is the same that the average surface temperature of any side, which is the same temperature that the perfectly conducting planet, T (the .5 from halved incoming power and .5 from halved outgoing radiation cancel each other).

So : rotation raises temperature of a non-perfectly-heat-conducing planet, bringing its surface temperature closer to the perfectly-heat-conducting planet surface temperature.

Comment by hwold on Open Thread, Jun. 8 - Jun. 14, 2015 · 2015-06-16T15:39:15.955Z · score: 1 (1 votes) · LW · GW

Yes, "intrication" is the standard translation of "entanglement" in QM. But nobody else uses it, and therefore I fear there is an obvious failure mode where someone Googles it and start shouting "WTF is that?"

Comment by hwold on Open Thread, Jun. 8 - Jun. 14, 2015 · 2015-06-16T15:18:31.441Z · score: 0 (0 votes) · LW · GW

"évidence" the noun is just a shorthand for "obvious thing" (most typical usage is « C’est l’évidence même » = “It’s obvious”. « Ce n’est pas la peine d’asséner de telles évidences » = “Such obvious things are not worth stating”).

Comment by hwold on Open Thread, Jun. 8 - Jun. 14, 2015 · 2015-06-16T15:05:49.965Z · score: 1 (1 votes) · LW · GW

Great suggestion, I’ll look into that.

Comment by hwold on Open Thread, Jun. 8 - Jun. 14, 2015 · 2015-06-12T09:42:09.187Z · score: 0 (0 votes) · LW · GW

Yes, that means « obvious »/« self-evident »

Comment by hwold on Open Thread, Jun. 8 - Jun. 14, 2015 · 2015-06-11T16:48:23.609Z · score: 3 (3 votes) · LW · GW

I’m trying to translate some material from LessWrong for a friend (interested with various subjects aborded here, but can’t read english…), and I’m struggling to find the best translation for “evidence”. I have many candidates, but every one of them is a little bit off relative to the connotation of "evidence". Since it’s a so central term in all the writings here, I figured out that it could not be bad to spend a little time finding a really good translation, rather than a just-okayish one.

• Could you find a few different sentences that would cover all (slighty differenrt) usages of evidence ? The objective is, if my translation fit well in all those propositions, there is good chances that it will fit well in everything i may want to translate. For example, from wiki : “Evidence for a given theory is the observation of an event that is more likely to occur if the theory is true than if it is false” “Generalization from fictional evidence” “Conservation of expected evidence”. I except that finding a translation that will cover equally well those three usages will basically cover any usage, but can you think of a 4th usage that may prove problematic even for a term that fit well for the 3 others ?
• What would be the less bad synonym of “evidence” : clue, proof, observation, sign (that’s basically my best candidates, translated back in english). I dislike all of them, but that’s the best candidates I found, translated back in english. (substitute evidence in all the test sentences abole, and you will understand my problem. “Clue for a given theory…” is somewhat good, but “conservation of expected clue” less so…)

J’ai comme candidats : « preuve », « indice », « signe », « observation ». D’autres propositions ? Laquelle vous semble la meilleure ?

(and don’t get me started on “entangled with”, I think I will lose much hair trying to find an acceptable translation for that one. French sucks.)

Comment by hwold on Rationality Quotes Thread February 2015 · 2015-02-02T14:11:12.913Z · score: 2 (2 votes) · LW · GW

Can’t tell for the Romantic Manifesto, but in Atlas Shrugged, Ayn Rand uses the word “value” as a synonym of “rule of conduct”. For example, she argue that “rational evaluation” is a correct value for man in the same way that “flying” is a correct value for birds.

She calls her philosophy objectivism because the thinks that correct values, which means rules of conduct that leads to environmental fitness (in her words says : “survival”), are objective.

Comment by hwold on Stupid Questions February 2015 · 2015-02-02T14:02:07.461Z · score: 6 (6 votes) · LW · GW

I still don’t understand HOW cancer kills.

I mean, we just have some additional cells who does not perform their normal functionality. But we still have a big bunch of normal, functioning cells.

In my (very very) distant family, someone died from lung cancer a few months ago. I still don’t understand the link between the few additional cells in his lungs and the acute hepatic failure that killed him.

I read somewhere that a primary cancer seldom kills ; most of the time the metastasic-induced does. Why ? There should be far more "bad" cells in the primary site, doesn’t it ?

(medecine illiterate there, sorry if half of my assumptions are wrong)

Comment by hwold on Open thread, Jan. 26 - Feb. 1, 2015 · 2015-01-26T16:15:33.604Z · score: 5 (5 votes) · LW · GW

A few day ago, I saw an interesting article on a site somewhat related to lesswrong. Unfortunately I didn’t have the time to read it, so I bookmarked it.

Computer crashed, lost my last bookmarks and now I spent 2 hours trying to find this article, without luck. Here is the idea of the article, in a nutshell : we human are somewhat a king of learning machine, trying to build a model of the “reality”. In ML, overfitting means that in insisting too much on fitting the data, we actually get a worse out-of-sample performance (because we start to fit the modeling noise and the stochastic noise). By carrying this ML idea into the human realm, we can argue that insisting too much on consistency can be a liability rather than an asset in our model-building.

Does that decription rings someone bells ? If yes, please link the article :)