All of btrettel's Comments + Replies

Amusingly enough, I got into the conference this year early. This seems to be a small piece of evidence for my hypothesis that these sorts of applications often work as lotteries.

I was able to get a copy of this via interlibrary loan some time ago, after finding much better citations.

Got this from a website that sells copies of Russian dissertations.

I definitely pulled out all the stops on this dissertation, and learned a fair amount in the process. If you're not living in Russia, and looking for a Russian dissertation, I would be a good person to contact. I can't get you the dissertation but I can put you in contact with people who can.

I don't see how that would be a problem. Perhaps I'm missing something, so if you could explain I'd be appreciative.

Usually the problem is that wavelengths smaller than the grid size obviously can't be resolved. A class of turbulence modeling approaches can help with that to a certain extent. This class of methods is called "large eddy simulation", or LES for short. You apply a low pass filter to the governing equations and then develop models for "unclosed" terms. In practice this is typically done less rigorously than I'd like, but it... (read more)

You'd be more likely to get some kind of waves that propagate at fixed speed along the grid, giving you a privileged rest frame, like in the old discredited theories of aether.

I'll try to steelman Florian_Dietz.

I don't know much anything about relativity, but waves on a grid in computational fluid dynamics (CFD for short) typically don't have the problem you describe. I do vaguely recall some strange methods that do in a Lagrangian CFD class I took, but they are definitely non-standard and I think were used merely as simple illustrations of a class of m... (read more)

I only skimmed this post, but I want to point out that most computational physics (and engineering) uses discretized space and time much as you've described. This is not new, just how things are often computed in practice.

Whether or not reality is discrete in this sense is beyond my knowledge as an engineer, but I have had conversations with physicists about this. (As I recall, it's possible, but the spatial and temporal resolution would be very small.)

Also, there are some exact solutions for discretized physics like this, but in general it's harder to do.... (read more)

I can see that I misremembered the lecture. Seems to be an application of Bayes as Lumifer suggested for the basic approach. Other more complex approaches were also discussed.

While I don't have my notes in front of me, I do recall from the decision analysis class I recently took that log score is related to the weight one would give to one forecaster among several when combining forecasts. Unfortunately it does not appear that the professor uploaded the slides on ensemble forecasting, so I can't provide any more right now. I am emailing the professor. Thought this would help in the meantime.

Thanks for pointing out that post by nostalgebraist. I had not seen it before and it definitely is of interest to me. I'm interested in hearing anything else along these lines, particularly information about solving this problem.

• Citation: Богданович И. И. Влияние подготовки топлива в форсунке на тонкость распыла. Дисс. канд. техн.наук. М., 1948, 136 с. (Bogdanovich I. I. Influence of fuel preparation in the nozzle on the spray fineness. Diss. cand. Technical Sciences. Moscow, 1948, 136 pp.)

• library URL: http://search.rsl.ru/en/record/01000176055

Old Russian dissertation. As far as I can tell, this is only available at the Russian State Library. If anyone could visit that library and scan the dissertation, I'd be appreciative.

I'd be more than willing to fulfill a similar reques... (read more)

The author was kind enough to scan their thesis and email me a copy.

While only having read the abstract at the moment, this seems to confirm my belief that one should generate a large amount of hypotheses when one wants a more rigorous answer to a question. I've started doing this in my PhD research, mostly by compiling others' hypotheses, but also by generating my own. I've been struck by how few researchers actually do this. However, the researchers who indeed do consider multiple hypotheses (e.g., in my field one major researcher who does is Rolf Reitz) earn greater respect from me.

Also, hypothesis generation is definit... (read more)

Poetry, along with some other art forms, always struck me as inherently uninteresting to the point where I find it hard to believe anyone actually enjoys it. I see some people who are obviously moved by poetry, so clearly I'm just at one end of the spectrum. To each their own.

Visited the Library of Congress this past Wednesday. I'll be going to the Library of Congress several times this summer, so reply to one of my comments here if you want anything in particular at the Library of Congress.

It was a fairly productive day, as I think I've found a good strategy for avoiding the phone book people at the scanner. For some reason, there's often a ton of people who do nothing other than look at old phone books. I assume this is for some sort of private investigator business or something along those lines. I never asked. Anyway, they ... (read more)

I hoped it would be possible to extract the data from the diagram, but no, the jpg in the pdf is sufficiently low-resolution that it doesn't work.

I have been compiling a lot of data for part of my PhD and this is a lot more common than I am comfortable with. Personally, as a reviewer I've decided to outright reject papers that don't allow one to extract the data. My preference would be requiring publishing the data straight up, but I can see an editor viewing this as unreasonable, or an author not knowing how to publish data.

With this being said, it's w... (read more)

r/UCDavis has confirmed that this can't be downloaded from HathiTrust if you are a UCD student. Someone there pointed out a copy at UC Berkeley that might be obtainable. Trying that now.

I'll be visiting the Library of Congress next week for one day. Let me know here if there's anything in particular you might want me to look at or scan there.

To keep this manageable, I'll only accept requests that appear difficult to obtain elsewhere. If it looks like you can get what you want via interlibrary loan, try that rather than asking me. If you are not affiliated with a university then I'd recommend talking to a librarian at a public library about this. Seems many public libraries will do interlibrary loan for free or a fee.

Likely I'll make a second trip to the Library of Congress in August, too.

This reminds me of something my father, a retired patent examiner, told me once. For a certain legal procedure the US Patent Office has a form letter a lawyer can use that contains all of the relevant information in a convenient format. My father was amazed by lawyers who refused to use it and instead wrote their own version of it. This seems like a waste of time for both the lawyer and examiner. When my father asked why, at least one lawyer told him that they believed the standard form had legal implications they didn't like, though my father insisted that case law made it clear that was wrong here.

Another (cynical) hypothesis is that these lawyers are paid by the hour and that they actively wanted to waste time.

R. D. Monson, "Experimental studies of cylindrical and sheet jets with and without forced nozzle vibrations" M.S. thesis, Dept. of Mech. Engr., Univ. of Calif., Davis (December 1980).

UC Davis refuses to loan this for unknown reasons. What I find odd is that it has already been digitized. UC Davis students might be able to download it here. Let me know if you can download it.

Good point. Ideal would be entering a number. If I recall correctly the actual guidelines are written in terms of MET-minutes, a weird exercise specific unit of energy. The entire "moderate intensity exercise" thing is a simplification of the actual recommendation. I'm not sure how much participation would decrease if we generalized from binary in this way.

I'd be interested in a question about aerobic fitness. My impression is that most rationalists severely underrate aerobic physical activity compared against anaerobic, which is surprising because anaerobic doesn't help cardiovascular capacity much. Presumably given the interest in cryonics and whatnot here, rationalists are interested in living longer. Cardiovascular capacity (VO2max, typically) is strongly correlated with longevity, and it's easy to see the direction of causation.

Possible question: "Over the past month, have you typically met the US ... (read more)

If you think in terms of QALYs, that could be one reason to prefer interventions targeted at children. Your average child has more life to live than your average adult, so if you permanently improve their quality of life from 0.8 QALYs per year to 0.95 QALYs per year, that would result in a larger QALY change than the same intervention on the adult.

This argument has numerous flaws. One which comes to mind immediately are that many interventions are not so long lasting, so both adults and children would presumably gain the same. It also is tied to particular forms of utilitarianism one might not subscribe to.

Omnilibrium was nominally supposed to be a rationalist political discussion website, but it seems to have died.

I have been too busy to participate much, but I did find my brief time there to be valuable, and would be interested in seeing the website become more active again.

I spidered his site with wget at one point. I'd be happy to provide a copy to anyone who wants it, but I'm afraid wget did not get everything, e.g., the image in question here would probably not have been found by wget.

A copy is available from the Internet Archive.

Romashka, I appreciate the reply.

Yes, I remember that post. It was 'almost interesting' to me, because it is beyond my actual knowledge. So, if you could just maybe make it less scary, we landlubbers would love you to bits. If you'd like.

If you don't mind, could you highlight which parts you thought were too difficult?

Aside from adding more details, examples, and illustrations, I'm not sure what I could change. I will have to think about this more.

re: errors. I mean that it seemed to me (probably wrongly) that if you measure a bunch of variables, and

Sure, I'd be interested in writing an article on dimensional analysis and scaling in general. I might have time over my winter break. It's also worth noting that I posted on dimensional analysis before. Dimensional analysis is not as popular as principal components analysis, despite being much easier, and I think this is unfortunate.

I don't know what a "ribbon-shaped population" is, but I imagine that fern spores are blown off by wind and then dispersed by a combination of wind and turbulence. Turbulent dispersion of particles is essentially an e... (read more)

The test labeled me as a "rationalist".

Glad to help. I'll go through your recommendations later this month when I have more time.

Thanks for the detailed reply, sen. I don't follow everything you said, but I'll take a look at your recommendations and see after that.

I can probably give a better answer if I know more precisely what you're referring to. Do you have examples of fluid dynamicists simplifying equations and citing group theory as the justification?

Unfortunately, the subject is rather disjoint. Most fluid dynamicists would have no idea that group theory is relevant. My impression is that some mathematicians have interpreted what fluid dynamicists have done for a long tim... (read more)

Creativity is another big area that seems neglected. I've read a fair amount on the subject, but feel I have barely touched the surface.

I also feel it probably is relevant to AI, so I'm somewhat surprised to see so little discussion of it here. (By "AI" I mean a number of things here. Might be easiest to see it as application of computers to solve problems.) At the moment, AI works when the actions one can take are clear (e.g., small number of valid moves in a game). When the possible actions are not precisely specified, the specification becomes the issue. Generating these possibilities is not trivial, and frequently this is what creativity is.

Is there a single book or resource you would recommend for learning how group theory/symmetry can be used to develop theories and models?

I work in fluid dynamics, and I've mainly seen group theory/symmetry mentioned when forming simplifying coordinate transformations. Fluid dynamicists call these "dimensionless parameters" or "similarity variables". I am certain other fields use different terminology.

The Library of Congress does not have these proceedings, unfortunately.

As a cyclist, I'd be interested in seeing these articles as well.

Unfortunately my university doesn't have any of these. I could request them by interlibrary loan, but I suspect I'd be on break by the time they come in.

I usually visit the Library of Congress when visiting my parents on breaks, and I'll check their catalog to see if they have these proceedings later. Their online catalog is not working at the moment. I'll make a new reply to your comment when I do.

I've had good experience with MyFitnessPal with respect to speed, and find the features sufficient for my purposes. I manually enter my exercise data, so I can not comment on automatic exercise tracking.

I found FitDay to be annoyingly slow, but I used the site for years before MyFitnessPal.

Learning of the reputation of the journal from someone knowledgeable about its field is the most reliable way I can think of for someone outside the field of interest.

Impact factors seem inappropriate to me, as they can vary wildly between fields and even wildly among subfields. A more specialized, but still high quality, journal could have a much lower impact factor than a more general journal, even if the two are at roughly the same average quality. Also, some foreign language journals can be excellent despite having low impact factors for the field of t... (read more)

I want to show that fighting aging is underestimated from effective altruistic point of view. I would name it second most effective way to prevent sufferings after x-risks prevention.

I'd be very interested in seeing this.

I think life extension should be discussed more here.

Many rationalists disappointment me with respect to life extension. Too many of them seem to recognize that physical conditioning is important, yet very few seem to do the right things. Most rationalists who understand that physical conditioning is important think they should do something, but that something tends to be almost exclusively lifting weights with little to no cardiovascular exercise. (I consider walking to barely qualify as cardiovascular exercise, by the way.) I think both are important, bu... (read more)

A big gap I see is memory. Having read a few books on learning and memory, I think what's been posted on LessWrong has been fragmented and incomplete, and we're in need of a good summary/review of the entire literature. There's a lot of confusion on the subject here too, e.g., this article seems to think spaced repetition and mnemonics are mutually exclusive techniques, but they're not at all. When I used Anki I frequently used mnemonics as well. The article seems to be an argument against bad flash cards, not spaced repetition in general. Probably over a ... (read more)

Some sort of emoticon could work, like what Facebook does.

Personally, I find the lack of feedback from an upvote or downvote to be discouraging. I understand that many people don't want to take the time to provide a quick comment, but personally I think that's silly as a 10 second comment could help a lot in many cases. If there is a possibility for a 1 second feedback method to allow a little more information than up or down, I think it's worth trying.

Integration with predictionbook or something similar, to show a user's track record in addition to upvotes/downvotes. Emphasis on getting many people to vote on the same set of standardized predictions

This would be a top recommendation of mine as well. There are quite a few prediction tracking websites now: PredictionBook, Metaculus, and Good Judgement Open come to mind immediately, and that's not considering the various prediction markets too.

I've started writing a command line prediction tracker which will integrate with these sites and some others (e... (read more)

I'll second the suggestion that we should consider other options. While I know Vaniver personally and believe he would do an excellent job, I think Vaniver would agree that considering other candidates too would be a wise choice. (Narrow framing is one of the "villians" of decision making in a book on decision making he suggested to me, Decisive.) Plus, I scanned this thread and I haven't seen Vaniver say he is okay with such a role.

According to 538's survey more people reported that they comment to fix errors than anything else.

This doesn't mean that you're wrong, though, because it doesn't seem 538 asked why people stop commenting (based on my skim of the article; feel free to correct me).

Good point about regulatory issues. I've been thinking a lot about working on standards committees and whatnot as they actually have influence and many standards/regulations/codes are bad.

Using waste streams is one of the more basic efficiency engineering approaches, and at this point I think if large gains were to be had from those, we'd have them already.

As for condensing CO2, there are tons of ideas along those lines, but I'm not sure carbon capture is worthwhile. I'd need to see more economic analysis of those ideas, or better yet, test implementations... (read more)

I'm interested in predicting future events to prioritize technology research. I've been thinking about getting speakers with expertise in the future of computing, trends of resource availability and utilization, climate change, and clean energy to start.

Previously I thought futurism was all about making optimistic predictions, but since then I've found more futurists who make predictions I think are credible. I track my own on PredictionBook and am going to start using Metaculus and GJOpen soon.

And despite working on a PhD in engineering, I'm actually quit... (read more)

Thanks. I agree that those examples are problematic. Do you have the link for Trump being the most significant current existential risk? I think he's a major risk, but relatively less important than many other things.

The biggest risk from him is starting a major war and/or using nuclear weapons, but as I recall from speaking with Vaniver, not everyone thinks he's a higher risk than Clinton would be in that area.

I would have liked to, but they rejected my application. (Edit: I imagine I'm getting downvoted because I mentioned this. Note that this is not complaining. I tend to view application processes as close to lotteries, so I don't take this personally.)

The topics of the conference interest me greatly. Right now I'm planning on hosting some futurist related discussions through the Austin LessWrong group while coordinating with a local futurist group.

If you will attend and have the opportunity, I'd be interested in seeing a summary of your experiences at the conference.

Can you give some examples? I haven't paid much attention to this.

While we're on the topic, "politics is the mind-killer" isn't sufficiently broad in my opinion. People can frequently are "mind-killed" in other areas, especially when conflicts of interest are involved. My experience suggests certain topics like diet tend to go just as poorly as politics.

So I meant "p/s works" = "splitting sleep into multiple phases in certain ways does increase efficiency and makes you require less sleep"

This appears to be true if you must be sleep deprived. That is, if you want to operate at X% function, where X is less than 100, likely less than 70 or so, you would need to sleep a shorter duration on a polyphasic schedule than you would on a monophasic schedule. ("X% function" is somewhat vague, but I trust you understand what I mean.)

However, if you want high X% function (say, higher th... (read more)

You're mixing things together. If I adapted a polyphasic schedule and also fixed real issues in the process, and have now significantly better sleep due to fixing those, then I am not "mildly deluded yourself and are avoiding disconfirming evidence." [...] Instead, I am correctly observing better sleep and am just attributing it incorrectly. So those are different things.

You are correct. This is exactly what I meant by "I should have given these possibilities more consideration as well, and I do now.". I should have also changed the ... (read more)