Stupid Questions - September 2017

post by ChristianKl · 2017-09-27T09:51:54.246Z · LW · GW · 26 comments

The stupid questions thread was one of the regular threads on LessWrong. It's a place where no question is to stupid to be asked and anybody who answers is encouraged to be kind.

This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.

Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.


Comments sorted by top scores.

comment by seed · 2020-10-21T00:24:46.240Z · LW(p) · GW(p)

Eliezer mentioned on twitter that MIRI is looking for Haskell programmers. Why is there no mention of Haskell on the vacancy page?

Replies from: athom
comment by athom · 2020-10-21T03:40:05.784Z · LW(p) · GW(p)

Best guess: because they've found the Haskell expertise they were after. That tweet is nearly two years old now, and I'm pretty sure Ed Kmett joined more recently than that.

comment by seed · 2020-10-21T00:19:31.433Z · LW(p) · GW(p)

How come MIRI never hired a Living Library in 3 years?

Replies from: habryka4
comment by habryka (habryka4) · 2020-10-21T05:14:56.733Z · LW(p) · GW(p)

I know two people who I think trialed for it, but it never really worked out. But not confident about why, or whether MIRI is still interested in filling that position.

comment by ChristianKl · 2017-10-09T14:44:58.264Z · LW(p) · GW(p)

I don't think there's a good reason to increase the fontsize in this case.

comment by panickedapricott · 2017-09-29T23:14:07.680Z · LW(p) · GW(p)

Statistics Question here.
In a binomial distribution why is it useful to check if N * phat > 5 AND N * (1 - phat) > 5 when determining if it is a normal distribution?

N = number of samples
phat = number of successes / N

comment by StephensCreek · 2017-09-27T13:05:49.030Z · LW(p) · GW(p)

I've always been confused about how energy and gravity interact. Specifically- "why isn't a table using energy?" If I were to hold a dumbbell with my elbow at a 90 degree angle, it would take energy for me to keep gravity from pulling it down. However, I can place a dumbbell on a table and it could sit there for centuries. Is it using any energy to keep the dumbbell from falling down?

Replies from: gjm, Oscar_Cunningham
comment by gjm · 2017-09-27T13:21:57.175Z · LW(p) · GW(p)

No, the dumbbell-on-a-table is not using any energy to keep from falling down. What takes energy, in general, is not exerting a force but moving things against an opposing force. Getting the dumbbell up into the air takes energy; letting it fall again will release some energy; but that's a one-off, and there isn't any ongoing energy cost to keeping it in the same place.

(Why does the stuff on the surface of the earth not all fall inward and the earth collapse into a black hole? Because as well as the inward force those things experience due to gravity, there are also outward forces, mostly arising from electrostatic repulsion between the electrons on nearby atoms, and when something is sitting motionless on the ground that's because those forces balance one another. This is also what's happening to the dumbbell on the table.)

So maybe the real question here is not "how can the table hold the dumbbell up without expending energy?", but "how come my arm needs to use energy to hold the dumbbell up?". The answer to that is: while there are structures, like a table, that can hold a dumbbell up without using energy, your arm is not built one of them: because it's made from flexibly-articulated bits, and it's only able to achieve the same effect the table can by less efficient means. (But in exchange for that it gets the ability to do things the table can't, like moving the dumbbell around.)

Replies from: lahwran
comment by lahwran · 2017-09-27T20:19:31.333Z · LW(p) · GW(p)

Something about this seems not right, but I don't know enough to be sure if my intuition means anything. There's no energy cost to holding things apart? Surely heat is slightly higher than it'd be in lower gravity?

comment by Oscar_Cunningham · 2017-09-27T15:59:49.144Z · LW(p) · GW(p)

This is a good question. The answer is that it shouldn't take any energy to hold something in place, but your arms are very inefficient. When you keep one of your muscles contracted the individual cells in that muscle are all contracting and relaxing repeatedly. This burns energy. So for a human holding a dumbbell takes energy. But this is just an unfortunate consequence of the way muscles work. If the human body had some way to "lock" the skeleton into place then you would be able to hold a dumbbell for as long as you wanted.

Replies from: StephensCreek
comment by StephensCreek · 2017-09-27T16:43:39.077Z · LW(p) · GW(p)

I actually think that it would still use energy even if you could "lock" your skeleton in place, simply because there would still be a gravitational force acting on all of the atoms in your skeleton that would need to be counteracted. This sort of builds on what gim said above about the electrostatic repulsion in atoms balancing out the force of gravity on Earth, and I probably should have phrased my question better originally to tease out this issue. Essentially, my question is what is happening to that electrostatic energy that is keeping the Earth from collapsing? Is it being used up? Even if the two forces are roughly in balance, and there isn't any dramatic motion, surely there is some give and take between gravity and the electrostatic force on the atomic level. If so, then the electrostatic force really would be moving things against an opposing force, and that movement surely uses up energy. Right?

Replies from: gjm
comment by gjm · 2017-09-27T20:45:15.987Z · LW(p) · GW(p)

What keeps the earth from collapsing is not electrostatic energy (well, I guess you could probably describe it so it sounds that way, but I don't think that's the best way to describe it) and no, it isn't used up.

At a microscopic level, things do move around in various ways even when they're part of objects we think of as being in equilibrium. Heat is the name we give to this sort of jiggling about, and it's a form of energy. But in equilibrium the net force acting on those atoms is zero, so the jiggling isn't moving things against an opposing force.

("But wait, say one of those atoms jiggles just a tiny little bit. Then it's no longer in its equilibrium position, which means that any further jiggling will be against an opposing force." Ah, but further jiggling may move it the other way, in which case the atom is gaining energy instead of losing it. On average it stays in the same place and the net energy change adds up to zero.)

In the very long term the jiggling will reduce, not because energy is being used up holding things apart but because heat tends to spread itself out uniformly (the jiggling spreads to other nearby things) and the average temperature of the universe (temperature is a measure of heat per available way-of-moving, which is kinda like heat per molecule) is rather small -- so in the long run everything gets pretty cold. In the short term, the dumbbell is at about the same temperature as the other stuff around it, and the flow of heat out of it is matched by the flow of heat into it.

But the key thing here is that exerting a force, as such, does not consume energy. The earth is not radiating away energy as it exerts a gravitational pull on everything else in the universe. An electron is not radiating away energy as it exerts an electrostatic attraction or repulsion on every other charged object in the universe. This may be counterintuitive if you think of energy as that stuff that everything needs in order to do anything, but the moral is that that isn't quite the right way to think of energy.

Replies from: StephensCreek
comment by StephensCreek · 2017-09-28T14:21:38.759Z · LW(p) · GW(p)

Very interesting. Thanks!

comment by ChristianKl · 2017-09-27T10:08:27.464Z · LW(p) · GW(p)

The resolution of the iPhone X is 1125 x 2436. If I buy a new 24 inch monitor Wirecutter currently recommends a monitor has a resolution of 1,920 × 1,200 Pixel.

What's happening here? We aren't monitor producers trying to sell us monitors with a higher resolution?

Replies from: blob, Elo, gjm
comment by blob · 2017-09-27T12:14:20.143Z · LW(p) · GW(p)

The typical distance between your eyes and the display is closer for a smartphone than for a monitor. If you had both and they had the same resolution the smartphone-pixel would usually take up more of your field of view than the monitor-pixel. The closer the display is to your eyes, the more pixels you'd like it to have. Think about VR headsets as an extreme case: their displays have resolutions like 2160x1200 and people complain that they can see every pixel.

And relating to that, adding more pixels has diminishing returns. Personally for instance I don't care about adding more pixels to current-gen monitors (while keeping the size constant; larger screens need more pixels). Some people would certainly be able to make use of it, but I would hardly benefit. Improvements in color would be very nice though and it's nice to see things start moving into that direction.

Replies from: gjm
comment by gjm · 2017-09-27T12:16:21.467Z · LW(p) · GW(p)

The typical distance between your eyes and the display is closer for a smartphone than for a monitor.

That's true and relevant but clearly only part of the story, because for some time almost all mobile phones have had displays whose resolution is high enough that in normal use even people with quite good eyesight don't see individual pixels, whereas even now most monitors don't have that property.

Replies from: blob
comment by blob · 2017-09-27T12:20:34.780Z · LW(p) · GW(p)


My slightly grumpy theory is that Apple introduced silly-high dpis as a unique selling point and the other manufacturers had to follow. Sure, some increase in pixel density was useful but they overshot the ideal. (maybe my eyesight is worse than usual, or I have atypical usecases?)

Replies from: ChristianKl
comment by ChristianKl · 2017-09-27T12:52:35.842Z · LW(p) · GW(p)

I'm not sure you would consciously notice an improvement in the display quality that would increase your reading speed by 2% or that would make you less tired while reading.

comment by Elo · 2017-10-20T22:32:38.540Z · LW(p) · GW(p)

My understanding is that there is a limit of what resolution the human eye can resolve.

When Steve Jobs launched the iPhone 4, and with it the first Retina display, he described it as having a screen with so many pixels packed closely together that they were imperceptible to the human eye at a distance of twelve inches. He went to great lengths to explain that, because the iPhone 4’s screen packed in 300 pixels per inch, most people wouldn’t see them at all when the phone was a foot from their eyes.

comment by gjm · 2017-09-27T12:06:57.675Z · LW(p) · GW(p)

They are. For instance, here are some you can buy from Amazon. Maybe the question is why they aren't trying very hard to sell us higher-resolution monitors, and I don't know the answer to that. At no time have I understood why users and vendors of computer displays seem so uninterested in their resolution.

But I think part of the story is that if, at roughly fixed physical size, you increase the resolution a lot then either everything becomes very small or you need some sort of fancy resolution-dependent scaling, and the first is bad for users and the second requires either extra work from all software creators or some sort of cleverness in the operating system that delivers nice-looking results even on displays whose resolution is very different from what applications are implicitly expecting.

Those are both things that are just starting to happen recently in the world of Actual Computers. It was able to happen earlier in the world of mobile devices because the OS vendors have more power and individual application authors have less freedom there, and because the whole industry got started later when it was easier to see that display resolutions might improve a lot.

comment by ChristianKl · 2017-10-09T14:43:53.848Z · LW(p) · GW(p)

Does IOTA work at scale? Can it work without real incentive for anyone to store transaction data?

comment by hamnox · 2017-09-27T19:33:37.558Z · LW(p) · GW(p)

What records of your childhood are you supposed to have as an adult?

Replies from: Gyrodiot, polymathwannabe
comment by Gyrodiot · 2017-09-28T15:40:17.999Z · LW(p) · GW(p)

I don't think there is much material records you're supposed to have besides the administrative and medical history polymathwannabe mentioned.

However, as mental record I would add are the memories of the places you've lived in, and significant experiences you've had. You can make some up, but you're supposed to have a story to tell if someone asks small talk questions, unless you're prepared to signal "I don't want to talk about my childhood".

comment by polymathwannabe · 2017-09-27T22:30:23.708Z · LW(p) · GW(p)

At the barest minimum, your birth certificate (and associated papers that prove your relatedness to people you hope to inherit from), your high school diploma (unless you already have a university degree AND don't intend to pursue another one), and any vitally important medical records.

comment by rox · 2017-10-25T11:53:05.193Z · LW(p) · GW(p)

Is existence bias a thing? If so, are we likely to make errors wrt x-risk mitigation as a result? (My thoughts on this topic are pretty confused, so help disentangling would be great.)

I find the Metzinger argument somewhat compelling.:*

I expect that if you value experience itself, rather than just valence of experience, one would be more opposed to negative utilitarianism, and certainly to accepting that our pull for existence is a bias. But if you're a classical hedonic utilitarian, or (Metzinger seems to argue) even a preference utilitarian, our draw towards continued existence could have us neglect the net value of our experiences.

My amenability to this line of argument is in part predicated on some credence in humans being bad at knowing and acting on their true preferences (i.e. a strong form of the findings of behavioral economics).

* I say "somewhat" because I find his framing to be a bit leading. His premise is that a benevolent superintelligence comes to a bunch of conclusions about what deserves moral worth, which look a lot like negative utilitarianism. While he says this is just a thought experiment used to highlight our impulse in favor of existence, I think he separately believes the moral claims he's making, and is using this as a means of arguing it. I think you could use the framework he has here to argue for all sorts of repugnant things and therefore claim that people have a bias against the repugnant outcome.