Open thread, May. 1 - May. 7, 2017
post by Thomas · 2017-05-01T15:55:32.361Z · LW · GW · Legacy · 29 commentsContents
29 comments
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29 comments
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comment by WalterL · 2017-05-01T19:53:08.634Z · LW(p) · GW(p)
I am constantly vexed by people who want time estimates before they give requirements. They teach us to say 'no' to this, in college, but it turns out you can't do that in the real world. So we are placed in the position of estimating how long it will take to code 'something', without enough detail about what the 'something' is to allow us to make an educated guess.
It's maddening.
Replies from: Screwtape, Lumifer, Elo, TheOtherDave↑ comment by Screwtape · 2017-05-01T20:45:13.934Z · LW(p) · GW(p)
My standby is "From what you've described, it would take about $X days" where X is an estimate that assumes that they want everything associated with what they've said. (So, if they asked for messaging, I assume they want user icons, some kind of friends list or department groupings, and probably file transfer too.) There is a genuine use case for this! If your business guys are non-techies, they might know that adding some feature will probably earn Y dollars, but don't know how much it would cost to add. In those cases, they're really looking to estimate if it's worth it; if they're doing things right, the next step if it looks good is to actually sit down and write up a solid spec.
Of course, lots of places aren't like that. At my job, my estimate is continued with "but I could be pretty far off in either direction. Can you tell me more specifically..." and then from there try and guide them into giving me actual requirements. I write down the main points of what they're asking for, say it back to them when they're finished and make any revisions, and then email them that. If they agree that's what they meant, then I start working on it.
This still doesn't quite work. I've had my spec change radically two or three times a sprint (two week block) or been informed they assumed certain things were just obvious parts of what they asked for. (Like the messaging = file transfer thing. That was uh, non-intuitive, though I should have seen that coming since most major messaging systems have it.) In the end, the most important thing is to make sure you get paid for it. If I'm getting money to sit at a keyboard and think, I'll get over throwing out half the code I write.
If you want more advice on constructively dealing with it, I'm sure there are people here with more experience than I have. If you're looking for commiseration, you have mine.
Replies from: Viliam, WalterL↑ comment by Viliam · 2017-05-04T17:17:24.202Z · LW(p) · GW(p)
if they asked for messaging, I assume they want user icons, some kind of friends list or department groupings, and probably file transfer too.
If they want to edit something in a web application, I assume they will also want the ability to edit the data on a smartphone without internet connection.. and then upload the changes later when they get online, and of course have all the edit conflicts magically resolved correctly without any user intervention. Did I mention it is supposed to work on all kinds of smartphones and notebooks?
(Ok, I am lying, I actually didn't assume this... and it actually happened.)
↑ comment by WalterL · 2017-05-02T14:58:05.301Z · LW(p) · GW(p)
Thanks for the advice, but your username makes me reluctant to take it :).
Replies from: Screwtape, Daniel_Burfoot↑ comment by Screwtape · 2017-05-02T18:02:20.464Z · LW(p) · GW(p)
My advice is always of the utmost sincerity, my dear Walterwood. The safest road to awful software is the gradual one- the gentle slope, soft underfoot, without sudden turnings, without milestones, without signposts. The duty of planning tomorrow's work is today's duty; though its material is borrowed from the future, the duty, like all duties, is in the Present. The truth is that wherever a developer has a meeting with a manager, there, whether they like it or not, a transcendental relation is set up between them which must be eternally enjoyed or eternally endured.
Put simply; to decide what the best use case is, you must ask what use the Management wants to make of it and then do the opposite. We know that is ultimately what they will decide. Only by our incessant efforts is the demand for infinite, or unrhythmical, change kept up.
Should you continue to find reason to distrust me, perhaps at some meetup or another I might take the opportunity to have you for dinner. >:)
Replies from: Lumifer↑ comment by Daniel_Burfoot · 2017-05-03T01:02:01.299Z · LW(p) · GW(p)
LessWrong: kind of an odd place to find references to Christian ethical literature.
Replies from: Screwtape↑ comment by TheOtherDave · 2017-05-01T20:04:39.284Z · LW(p) · GW(p)
Back when this was a big part of my professional life, my reply was "everything takes a month."
comment by Thomas · 2017-05-01T15:56:47.320Z · LW(p) · GW(p)
A problem to ponder:
https://protokol2020.wordpress.com/2017/04/30/several-big-numbers-to-sort/
Replies from: Oscar_Cunningham, madhatter↑ comment by Oscar_Cunningham · 2017-05-03T07:39:55.283Z · LW(p) · GW(p)
So in the comments of that page I was trying to prove that the number of possible molecules is infinite. I was trying to find some way of arranging an arbitrarily large molecule so that it didn't collapse gravitationally. I now think that a spherical shell with a constant thickness will work. The mass is proportional to the square of the radius, but it acts as though from a point at the centre, so the gravitational force on any point of the outside does not depend on the radius. Since small plastic spheres can exist, so can large ones.
Replies from: simon, Thomas↑ comment by simon · 2017-05-08T08:15:29.972Z · LW(p) · GW(p)
This would in fact turn into a black hole since a black hole's radius is proportional to its mass. Also, it would collapse due to compressive forces since the force between any pair of hemispheres is proportional to r^2 but the surface to bear the force is only proportional to r.
Replies from: Oscar_Cunningham↑ comment by Oscar_Cunningham · 2017-05-08T09:45:41.785Z · LW(p) · GW(p)
Yeah, I had already begun to worry about that second point, that the compressive pressure might be greater than I had imagined, but I couldn't see an easy way to calculate it. Your first point, that a black hole will form, is an easier way to see that this arrangement will fail. In fact I think the two points are different ways of looking at the same thing; for a black hole to form the shell must be pushed beyond the limit of its compressive strength.
What about a circular ring rather than a spherical shell? The mass is proportional to the radius, so it looks like it has a hope of working. But no, using the results of the paper here (behind a paywall, sorry) the pressure inside the ring rises with log(r), so it will eventually break.
:-(
Can we prove that all sufficiently large structures collapse?
Replies from: simon↑ comment by simon · 2017-05-08T16:38:53.940Z · LW(p) · GW(p)
Sketch of proof: you proved that a stick collapses (compression scaling as Log(L)).
Well every connected object is either a stick, a curvy stick, or one of those things plus some extra atoms. So - prove that making things curvy or adding atoms doesn't help (enough). So, e.g. thickening the stick in the middle won't save it since you'd need infinite thickness.
for a black hole to form the shell must be pushed beyond the limit of its compressive strength.
hmmm... we've been talking as if in a space without dark energy. But with dark energy, a sufficiently large shell could be balanced by the antigravity of the dark energy within it, the acceleration caused should scale linearly with the radius. So that would be able to be under no stress at all. But I'm not sure it wouldn't form a black hole at large radius. As the interior gets bigger and bigger, eventually you get a cosmological event horizon forming so the interior forms a white hole - so light can't leave the shell to the interior. Since it's balanced, for symmetry reason's I'd expect the same to apply on the exterior. So you have this shell black hole between an interior and exterior both 'outside' the black hole.
Of course, this shell would actually be crushed by the stress in the radial direction, it's only not under stress circumferentially. But, now that we've got this example, we can extend to an ultralight aerogel (space-o-gel?) that balances the dark energy everywhere. I'd expect this to look externally the same as the shell example, so it should also eventually form a black hole. These are just guesses though - not actually calculated.
Edit: I'm now very suspicious of this analogy between the sphere and space-o-gel and will have to think about it more.
Replies from: Oscar_Cunningham↑ comment by Oscar_Cunningham · 2017-05-08T22:21:11.275Z · LW(p) · GW(p)
I agree with what you've said. I'll have to think about it for a while.
I did look at the case of a spinning ring and it seems stable. But I'm only using the Newtonian approximation, and you have to spin it at a speed that increases like sqrt(log(r)) so eventually that's invalid.
Replies from: simon↑ comment by Thomas · 2017-05-03T08:42:03.808Z · LW(p) · GW(p)
This physics does not impress me, but the mathematical idea behind which you imply, impresses me very much!
I want to say, forget about the real molecules, but this spiral structure per se, is an interesting concept.
An arbitrary large mas can be glued together without collapsing into a black hole?
Very interesting, indeed!
↑ comment by madhatter · 2017-05-03T02:44:44.402Z · LW(p) · GW(p)
#1 is the smallest.
Replies from: Thomas↑ comment by Thomas · 2017-05-03T08:45:20.906Z · LW(p) · GW(p)
Could be. Seems possible, likely even.
Replies from: Oscar_Cunningham↑ comment by Oscar_Cunningham · 2017-05-03T11:19:11.674Z · LW(p) · GW(p)
Perhaps 9 is smaller if you count cryonics (or some other non-mystical method) as reincarnation.
Replies from: Thomascomment by dropspindle · 2017-05-06T14:56:31.879Z · LW(p) · GW(p)
It doesn't seem like there's been any discussion on caloric restriction or intermittent fasting since 2014, and even then it didn't seem like any consensus was achieved. Have there been any more studies in the intervening years? Has anyone else started or stopped or failed or whatnot?
Here's Gwern's write up: https://www.gwern.net/intermittent-fasting
(I just noticed that their post was modified in May 2017, so SOMETHING new must have happened...)
Replies from: MrMindcomment by madhatter · 2017-05-03T21:41:21.187Z · LW(p) · GW(p)
Hi all,
A friend and I (undergraduate math majors) want to work on either exploring a variant or digging deeper into the model introduced in this paper:
Any ideas?
Replies from: MrMind, madhatter↑ comment by MrMind · 2017-05-04T07:20:26.896Z · LW(p) · GW(p)
Some ideas:
- different enmities for different teams
- team capabilities drawn from a normal distribution
- utility that does not depend from safety or enmity
- only some team know their own / others capability
- the probability of winning the race depending on capability, not simply the highest capable team being the winner
etc.
Also, what it says in note 2.