Jeffrey Heninger

• Jeffrey Heninger 30 Mar 2024 3:53 UTC

  4 points

  1

  in reply to: Gerald Monroe’s comment on: Was a Sub­way in New York City Inevitable?

  The London subway was private and returned enough profit to slowly expand while it was coal powered. Once it electrified, it became more profitable and expanded quickly.

  The Baltimore tunnel was and is part of an intercity line that is mostly above ground. It was technologically similar to London, but operationally very different.

• Jeffrey Heninger 30 Mar 2024 2:33 UTC

  1 point

  0

  in reply to: Gerald Monroe’s comment on: Was a Sub­way in New York City Inevitable?

  I chose the start date of 1866 because that is the first time the New York Senate appointed a committee to study rapid transit in New York, which concluded that New York would be best served by an underground railroad. It’s also the start date that Katz uses.

  The technology was available. London opened its first subway line in 1863. There is a 1.4 mi railroad tunnel from 1873 in Baltimore that is still in active use today. These early tunnels used steam engines. This did cause ventilation challenges, but they were resolvable. The other reasonable pre-electricity option would be to have stationary steam engines at a few places, open to the air, that pulled cables that pulled the trains. There were also some suggestions of dubious power mechanisms, like the one you described here. None of the options were as good as electric trains, but some of them could have been made to work.

  This is not a global technological overhang, because there continued to be urban railroad innovation in other cities. It would only be overhang for New York City. This is a more restrictive definition of overhang than I used in my previous post, but it might still be interesting to see what happened with local overhang.

Was a Sub­way in New York City Inevitable?

• Jeffrey Heninger 26 Mar 2024 20:57 UTC

  3 points

  −3

  in reply to: Kaj_Sotala’s comment on: My De­tailed Notes & Com­men­tary from Sec­u­lar Solstice

  The original version of the song reads to me as being deist or pantheist. You could replace ‘God’ with ‘Nature’ and the meaning would be almost the same. My view of Divinely Guided Evolution has a personal God fiddling with random mutations and randomly determined external factors to create the things He wants.

  It is definitely anti-Young-Earth-Creationism, but it is also dismissive of the Bible. Even if you don’t think that Genesis 1 should be treated as a chronology, I think that you should take the Bible seriously. Its commentary on what it means to be human is important.

• Jeffrey Heninger 26 Mar 2024 20:42 UTC

  1 point

  0

  in reply to: Shankar Sivarajan’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  Many of these seem reasonable. The “book of names” sounds to me like the Linnaean taxonomy, while the “book of night” sounds like astronomical catalogues. I don’t know as much about geology, but the “book of earth” could be geological surveys.

  This kind of science is often not exciting. Rutherford referred to it as “stamp collecting.” It is very useful for the practice of future generations of scientists. For example, if someone wants to do a survey of various properties of binary star systems, they don’t have to find a bunch of examples themselves (and worry about selection effects) because someone else has already done it and listed them in a catalogue. It is nice to celebrate this kind of thankless work.

  The closing lines are weird: “Humans write the book of truth… Truth writes the world.” This sounds like constructivist epistemology. The rest of the song has empiricist epistemology: Truth is determined by the external world, not written by humans. Maybe something like “Humans can read the book of truth.… Truth comes from the world.” (Although this adds syllables...)

• Jeffrey Heninger 26 Mar 2024 20:18 UTC

  1 point

  0

  in reply to: RobertM’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  If it were done at Lighthaven, it would have to be done outdoors. This does present logistical problems.

  I would guess that making Lighthaven’s outdoor space usable even if it rains would cost much less (an order of magnitude?) than renting out an event space, although it might cost other resources like planning time that are in more limited supply.

  If Lighthaven does not want to subsidize Solstice, or have the space reserved a year in advance, then that would make this option untenable.

  It’s also potentially possible to celebrate Solstice in January, when event spaces are more available.

• Jeffrey Heninger 26 Mar 2024 20:11 UTC

  3 points

  0

  in reply to: jefftk’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  Staggering the gathering in time also works. Many churches repeat their Christmas service multiple times over the course of the day, to allow more people to come than can fit in the building.

• Jeffrey Heninger 26 Mar 2024 20:04 UTC

  1 point

  2

  in reply to: Cole Wyeth’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  There’s another reason for openness that I should have made clearer. Hostility towards Others is epistemically and ethically corrosive. It makes it easier to dismiss people who do agree with you, but have different cultural markers. If a major thing that unifies the community is hostility to an outgroup, then it weakens the guardrails against actions based on hate or spite. If you hope to have compassion for all conscious creatures, then a good first step is to try to have compassion for the people close to you who are really annoying.

  Christianity seems to be unusually open to everyone, but I think this is partially a side effect of evangelism.

  I endorse evangelism broadly. If you think that your beliefs are true and good, then you should be trying to share them with more people. I don’t think that this openness should be unusual, because I’d hope that most ideologies act in a similar way.

• Jeffrey Heninger 26 Mar 2024 19:24 UTC

  1 point

  0

  in reply to: jimrandomh’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  So I think the direction in which you would want Solstice to change—to be more positive towards religion, to preach humility/​acceptance rather than striving/​heroism—is antithetical to one of Solstice’s core purposes.

  While I would love to see the entire rationalist community embrace the Fulness of the Gospel of Christ, I am aware that this is not a reasonable ask for Solstice, and not something I should bet on in a prediction market. While I criticize the Overarching Narrative, I am aware that this is not something that I will change.

  My hopes for changing Solstice are much more modest:

  1. Remove the inessential meanness directed towards religion. There already has been some of this, which is great ! Time Wrote the Rocks no longer falsely claims that the Church tortured Galileo. The Ballad of Smallpox Gone no longer has a verse claiming that preachers want to “Screw the body, save the soul //​ Bring new deaths off the shelves”. Now remove the human villains from Brighter Than Today, and you’ve improved things a lot.

  2. Once or twice, acknowledge that some of the moral giants whose shoulders we’re standing on were Christian. The original underrated reasons to be thankful had one point about Quaker Pennsylvania. Unsong’s description of St. Francis of Assisi also comes to mind. If you’re interested, I could make several other suggestions of things that I think could be mentioned without disrupting the core purposes of Solstice.

• Jeffrey Heninger 26 Mar 2024 18:17 UTC

  1 point

  0

  in reply to: Raemon’s comment on: Gen­eral Thoughts on Sec­u­lar Solstice

  also it’s a lot more work to setup

  How hard would it be to project them? There was a screen, and it should be possible to project at least two lines with music large enough for people to read. Is the problem that we don’t have sheet music that’s digitized in a way to make this feasible for all of the songs?

• Jeffrey Heninger 26 Mar 2024 0:20 UTC

  6 points

  0

  in reply to: TheSkeward’s comment on: My De­tailed Notes & Com­men­tary from Sec­u­lar Solstice

  This is more volunteer-based than I was expecting. I would have guessed that Solstice had a lot of creative work, the choir, and day-of work done by volunteers, but that the organizers and most of the performers were paid (perhaps below market rates). As it is, it is probably more volunteer-based than most Christmas programs.
  
  I’ll edit the original post to say that this suggestion is already being followed.

My De­tailed Notes & Com­men­tary from Sec­u­lar Solstice

Gen­eral Thoughts on Sec­u­lar Solstice

• Jeffrey Heninger 1 Mar 2024 22:29 UTC

  41 points

  12

  on: The Parable Of The Fallen Pen­du­lum—Part 1

  This kind of situation is dealt with in Quine’s Two Dogmas of Empiricism, especially the last section, “Empiricism Without the Dogmas.” This is a short (~10k words), straightforward, and influential work in the philosophy of science, so it is really worth reading the original.

  Quine describes science as a network of beliefs about the world. Experimental measurements form a kind of “boundary conditions” for the beliefs. Since belief space is larger than the space of experiments which have been performed, the boundary conditions meaningfully constrain but do not fully determine the network.

  The totality of our so-called knowledge or beliefs, from the most casual matters of geography and history to the profoundest laws of atomic physics or even of pure mathematics and logic, is a man-made fabric which impinges on experience only along the edges. Or, to change the figure, total science is like a field of force whose boundary conditions are experience. A conflict with experience at the periphery occasions readjustments in the interior of the field.

  Some beliefs are closer to the core of the network: changing them would require changing lots of other beliefs. Some beliefs are closer to the periphery: changing them would change your beliefs about a few contingent facts about the world, but not much else.

  In this example, the belief in Newton’s laws are much closer to the core than the belief in the stability of this particular pendulum.^[1]

  When an experiment disagrees with our expectations, it is not obvious where the change should be made. It could be made close to the edges, or it could imply that something is wrong with the core. It is often reasonable for science (as a social institution) to prefer changes made in the periphery over changes made in the core. But this is not always the implication the experiment makes.

  A particular example that I am fond of involves the perihelion drifts of Uranus and Mercury. By the early 1800s, there was good evidence that the orbits of both planets were different from what Newtonian mechanics predicted. Both problems would be resolved by the mid 1900s, but the resolutions were very different. The unexpected perihelion drift of Uranus was explained by the existence of another planet in our solar system: Neptune. The number of planets in our solar system is a periphery belief: changing it does not require many other beliefs to change. People then expected that Mercury’s unexpected perihelion drift would have a similar cause: a yet undiscovered planet close to the sun, which they named Vulcan. This was wrong.^[2] Instead, the explanation was the Newtonian mechanics was wrong and had to be replaced by general relativity. Even though the evidence in both cases was the same, they implied that there should be changes made at different places in the web of beliefs.

  1. ^

     Also, figuring things out in hindsight is totally allowed in science. Many of our best predictions are actually postdictions. Predictions are more impressive, but postdictions are evidence too.

     The biggest problem these students have is being too committed to not using hindsight.

  2. ^

     I would say that this planet was not discovered, except apparently in 1859 a French physician /​ amateur astronomer named Lescarbault observed a black dot transiting the sun which looked like a planet with an orbital period of 19 days.

     I would say that this observation was not replicated, except it was. Including by professional astronomers (Watson & Swift) who had previously discovered multiple asteroids and comets. It was not consistently replicated, and photographs of solar eclipses in 1901, 1905, and 1908 did not show it.

     What should we make of these observations?

     There’s always recourse to extremely small changes right next to the empirical boundary conditions. Maybe Lescarbault, Watson, Swift, & others were mistaken about what they saw. Or maybe they were lying. Or maybe you shouldn’t even believe my claim that they said this.

     These sorts of dismissals might feel nasty, but they are an integral part of science. Some experiments are just wrong. Maybe you figure out why (this particular piece of equipment wasn’t working right), and maybe you don’t. Figuring out what evidence should be dismissed, what evidence requires significant but not surprising changes, and what evidence requires you to completely overhaul your belief system is a major challenge in science. Empiricism itself does not solve the problem because, as Quine points out, the web of beliefs is underdetermined by the totality of measured data.

• Jeffrey Heninger 22 Feb 2024 20:52 UTC

  2 points

  −1

  in reply to: tcheasdfjkl’s comment on: Con­stel­la­tions are Younger than Continents

  I’m currently leaning towards

  • kings and commonwealths and all

• Jeffrey Heninger 16 Jan 2024 19:14 UTC

  1 point

  0

  in reply to: mishka’s comment on: Com­mon­wealth Fu­sion Sys­tems is the Same Scale as OpenAI

  Tokamaks have been known for ages. We plausibly have gotten close to the best performance out of them that we could, without either dramatically increasing the size (ITER) or making the magnets significantly stronger. The high temperature superconducting^[1] ‘tape’ that Commonwealth Fusion has pioneered has allowed us to make stronger magnetic fields, and made it feasible to build a fusion power plant using a tokamak the size of JET.

  After SPARC, Commonwealth Fusion plans to build ARC, which should actually ship electricity to customers. ARC should have a plasma energy gain of Q~13, and engineering energy gain of about 3, and produce about 250 MWe. They haven’t made any public commitments about when they expect ARC to be built and selling electricity to the grid, but there has been some talk about the early 2030s.^[2]

  1. ^

     The higher temperature is not really what we care about. What we really want is higher magnetic field. These two properties go together, so we talk about ‘high temperature superconductors’, even if we’re planning on running it at the same temperature as before and making use of the higher magnetic fields.

  2. ^

     You don’t need to have any insider information to make this estimate. Construction of SPARC is taking about 4 years. If we start when SPARC achieves Q>5 (2026?), add one year to do the detailed engineering design for ARC, and then 4 years to construct ARC, and maybe a year of initial experiments to make sure it works as expected, then we’re looking at something around 2032. You might be able to trim this timeline a bit and get it closer to 2030, or some of these steps might take longer. Conditional on SPARC succeeding at Q>5 by 2028, it seems pretty likely that ARC will be selling electricity to the grid by 2035.

• Jeffrey Heninger 13 Jan 2024 15:19 UTC

  4 points

  1

  in reply to: RHollerith’s comment on: Com­mon­wealth Fu­sion Sys­tems is the Same Scale as OpenAI

  OpenAI has to face off against giants like Google and Facebook, as well as other startups like Anthropic. There are dozens of other organizations in this space, although most are not as competitive as these.

  Commonwealth Fusion has to face off against giants like ITER (funding maybe $22B, maybe $65B, estimates vary) and the China National Nuclear Corporation (building CFETR at ?? cost, while a much smaller experiment in China cost ~$1B), as well as other startups like Helion. The Fusion Industry Association has 37 members, which are all private companies trying to get fusion.

  There’s probably currently more private investment in AI, and more public investment in fusion. Many of the investments are not publicly available, so a direct comparison between the entire fields is difficult. I choose to focus on two startups with available data that seem to be leading in their respective fields.

• Jeffrey Heninger 13 Jan 2024 15:03 UTC

  2 points

  1

  in reply to: RHollerith’s comment on: Com­mon­wealth Fu­sion Sys­tems is the Same Scale as OpenAI

  I thought about including valuation in the table as well, but decided against it:

  • I’m not sure how accurate startup valuations are. It make be less clear how to interpret what the funding received means, but the number is easier to measure accurately.

  • These are young companies, so the timing of the valuation matters a lot. OpenAI’s valuation is recent, or 8 years after the company was founded. Commonwealth Fusion’s valuation is from 2 years ago, or 4 years after the company was founded. If each had multiple valuations, then I would have made a graph like Figure 1 for this.

• Jeffrey Heninger 13 Jan 2024 14:58 UTC

  1 point

  −4

  in reply to: Gerald Monroe’s comment on: Com­mon­wealth Fu­sion Sys­tems is the Same Scale as OpenAI

  The cost to build a tokamak that is projected to reach Q~10 has fallen by more than a factor of 10 in the last 6 years. CFS is building for $2B what ITER is building for maybe $22B, maybe $65B (cost estimates vary).

  It’s really not clear what the cost of fusion will end up being once it becomes mass produced.

• Jeffrey Heninger 13 Jan 2024 14:48 UTC

  4 points

  0

  in reply to: mishka’s comment on: Com­mon­wealth Fu­sion Sys­tems is the Same Scale as OpenAI

  Helion has raised a similar amount of capital as Commonwealth: $2.2B. Helion also has hundreds of employees: their LinkedIn puts them in the 201-500 employees category. It was founded in 2013, so it is a bit older than CFS or OpenAI.

  My general sense is that there’s more confidence in the plasma physics community that CFS will succeed than that Helion will succeed.

  SPARC is a tokamak, and tokamaks have been extensively studied. SPARC is basically JET with a stronger magnetic field, and JET has been operational since the 1980s and has achieved Q=0.67. It’s only a small extrapolation to say that SPARC can get Q>1. Getting to Q~10 involves more extrapolating of the empirical scaling laws and trusting numerical simulations, but these are scaling laws and simulations that much of the plasma physics community has been working on for decades.

  Helion uses a different design. This design has been tested much less, and far fewer plasma physicists have worked on it. They also haven’t published as much data from their most recent experiment: last time I checked, they had published the temperature they had reached on Trenta, but not the density or confinement time. Maybe the unpublished results are really good, and suggest that the scaling that has worked so far will continue to work for Polaris, but maybe they’re not. It’s plausible that Polaris will get Q>1 when it is built (planned for 2024), but I’m not as confident about it.

  Also, Helion uses D-He3 rather than D-T. This means that they produce far fewer and less energetic neutrons, but it means that their targets for temperature and density /​ confinement time are an order of magnitude higher. Even if you think D-He3 is better in the long term (and it’s not clear that it is), using D-T for initial experiments is easier.