spxtr

Karma: 502

spxtr 16 Sep 2014 16:46 UTC
47 points
on: What are your contrarian views?
[Please read the OP before voting. Special voting rules apply.]

Feminism is a good thing. Privilege is real. Scott Alexander is extremely uncharitable towards feminism over at SSC.

Entropy and Temperature

spxtr17 Dec 2014 8:04 UTC

39 points

96 comments3 min readLW link

spxtr 6 Jun 2015 5:37 UTC
26 points
on: Agency is bugs and uncertainty
Story time! Shortly after Brawl came out, I got pretty good at it. I could beat all my friends without much effort, so I decided to enter in a local tournament. In my first round I went up against the best player in my state, and I managed to hit him once, lightly, over the course of two games. I later became pretty good friends and practiced with him regularly.

At some point I completely eclipsed my non-competitive friends, to the extent that playing with them felt like a chore. All I had to do was put them in certain situations where I knew how they would react and then punish. It became a simple algorithm. Get behind them in shield, wait for the roll, punish. Put them in the air, jump after them, wait for the airdodge, punish. Throw them off the ledge, wait for the jump, punish. It felt like I was playing a CPU.

Meanwhile, I still couldn’t reliably beat the best player from my state. One day, after he took off a particularly gruesome stock, I paused and, exasperated, asked for advice. We watched a replay and he showed me how I responded to certain situations in the same way every time, leading to a punish. My habits were less obvious than those of my friends, but they were still habits. He said, “you play like a robot, in a bad way.”

So yeah. In that context, I’ve downgraded friends to CPUs because of their predictability, and been downgraded to a CPU by omega, because of my predictability.

spxtr 17 Feb 2015 19:53 UTC
21 points
in reply to: Curiouskid’s comment on: Open thread, Feb. 16 - Feb. 22, 2015

Feynman was younger than 15 when he took it, and very near this factoid in Gleick’s bio, he recounts Feynman asking about very basic algebra (2^x=4) and wondering why anything found it hard—the IQ is mentioned immediately before the section on ‘grammar school’, or middle school, implying that the ‘school IQ test’ was done well before he entered high school, putting him at much younger than 15. (15 is important because Feynman had mastered calculus by age 15, Gleick says, so he wouldn’t be asking his father why algebra is useful at age >15.) - Given that Feynman was born in 1918, this implies the IQ test was done around 1930 or earlier. Given that it was done by the New York City school district, this implies also that it was one of the ‘ratio’ based IQ tests—utterly outdated and incorrect by modern standards. - Finally, it’s well known that IQ tests are very unreliable in childhood; kids can easily bounce around compared to their stable adult scores.

So, it was a bad test, which even under ideal circumstances is unreliable & prone to error, and administered in a mass fashion and likely not by a genuine psychometrician.

-- gwern

spxtr 4 Jan 2014 22:00 UTC
20 points
on: Rationality Quotes January 2014

The most traditional way to begin a study of quantum mechanics is to follow the historical developments—Planck’s radiation law, the Einstein-Debye theory of specific heats, the Bohr atom, de Broglie’s matter waves, and so forth—together with careful analyses of some key experiments such as the Compton effect, the Frank-Hertz experiment, and the Davisson-Germer-Thompson experiment. In that way we may come to appreciate how the physicists in the first quarter of the twentieth century were forced to abandon, little by little, the cherished concepts of classical physics and how, despite earlier false starts and wrong turns, the masters—Heisenberg, Schrodinger, and Dirac, among others—finally succeeded in formulating quantum mechanics as we know it today.

However, we do not follow the historical approach in this book. Instead, we start with an example that illustrates, perhaps more than any other example, the inadequacy of classical concepts in a fundamental way. We hope that by exposing the reader to a “shock treatment” at the onset, he or she may be attuned to what we might call the “quantum-mechanical way of thinking” at a very early stage.

-- Modern Quantum Mechanics by J. J. Sakurai, the standard graduate level quantum textbook. Following this quote is a discussion of the Stern-Gerlach experiment. I post this quote because it is in line with Quantum Explanations.

spxtr 29 Apr 2023 5:39 UTC
18 points
9
in reply to: LoganStrohl’s comment on: Locating Fulcrum Experiences
I suspect my experience is somewhat similar to shminux’s.
I simply can’t follow these posts, and the experience of reading them feels odd, and even off-putting at times (in an uncanny valley sort of way). At the same time, I can see that a number of people in the comments are saying that they find great value in them.
My first guess as to why I had trouble with them was that there are basically no concrete examples given, but now I don’t think that’s the reason. Personally, I get a strong sense of “I must be making some sort of typical mind fallacy” here. Something about our world views, or internal models of cognition, or something along those lines must be dramatically different. It’s hard to communicate just how difficult it is for me to make sense of these posts without being rude.
Thanks for the interesting read, and I love the watercolors.

spxtr 27 Jan 2015 3:40 UTC
14 points
in reply to: WalterL’s comment on: Open thread, Jan. 26 - Feb. 1, 2015
Quantum mysticism written on a well-known and terrible MRA blog? −8 seems high. See the quantum sequence if you haven’t already. It looks like advancedatheist and ZankerH got some buddies to upvote all of their comments, though. They all jumped by ~12 in the last couple hours.

For real, though, this is actually useless and deserves a very low score.

spxtr 17 May 2023 20:07 UTC
13 points
2
in reply to: Steven Byrnes’s comment on: $250 prize for checking Jake Cannell’s Brain Efficiency
I don’t think the thermal de Broglie wavelength is at all relevant in this context, nor the mean free path, and instead I’m trying to shift discussion to “how wires work”.
This is the crux of it. I made the same comment here before seeing this comment chain.
People have been sending binary information over wires since 1840, right? I don’t buy that there are important formulas related to electrical noise that are not captured by the textbook formulas. It’s an extremely mature field.
Also a valid point. @jacob_cannell is making a strong claim: that the energy lost by communicating a bit is the same scale as the energy lost by all other means, by arbitrarily dividing by 1 nm so that the units can be compared. If this were the case, then we would have known about it for a hundred years. Instead, it is extremely difficult to measure the extremely tiny amounts of heat that are actually generated by deleting a bit, such that it’s only been done within the last decade.
This arbitrary choice leads to a dramatically overestimated heat cost of computation, and it ruins the rest of the analysis.
@Alexander Gietelink Oldenziel, for whatever it is worth, I, a physicist working in nanoelectronics, recommend @Steven Byrnes for the $250. (Although, EY’s “it’s wrong because it’s obviously physically wrong” is also correct. You don’t need to dig into details to show that a perpetual motion machine is wrong. You can assert it outright.)
What links here?
- Brain Efficiency Cannell Prize Contest Award Ceremony by Alexander Gietelink Oldenziel (24 Jul 2023 11:30 UTC; 145 points)

spxtr 13 Mar 2015 2:23 UTC
13 points
on: Harry Potter and the Methods of Rationality discussion thread, March 2015, chapter 120

I didn’t want to tell it to you before because I thought it might prejudice your decision unfairly.

If Draco has has the last half-hour of his memory sealed off, then why does Harry say these words to him? Shouldn’t Draco respond, “What decision?”

Unless it’s a more nuanced memory charm, such that he only subconsciously remembers the conversation.

spxtr 18 Dec 2014 4:28 UTC
12 points
in reply to: shminux’s comment on: Entropy and Temperature
Maxwell’s demon, as criticized in your first link, isn’t omniscient. It has to observe incoming particles, and the claim is that this process generates the entropy.

spxtr 13 Jun 2014 6:36 UTC
11 points
on: List a few posts in Main and/or Discussion which actually made you change your mind
I regularly made these three mistakes.

spxtr 23 Aug 2023 5:56 UTC
9 points
−1
on: Implications of evidential cooperation in large worlds
I haven’t heard of ECL before, so I’m sorry if this comes off as naive, but I’m getting stuck on the intro.
For one, I assume that you care about what happens outside our light cone. But more strongly, I’m looking at values with the following property: If you could have a sufficiently large impact outside our lightcone, then the value of taking different actions would be dominated by the impact that those actions had outside our lightcone.
The laws of physics as we know them state that we cannot have any impact outside our light cone. Does ECL (or this post) require this to be wrong?
From the summary you linked,
Many ethical theories (in particular most versions of consequentialism) do not consider geographical distance of relevance to moral value. After all, suffering and the frustration of one’s preferences is bad for someone regardless of where (or when) it happens. This principle should apply even when we consider worlds so far away from us that we can never receive any information from there.
...
Multiverse-wide cooperation via superrationality (abbreviation: MSR) is the idea that, if I think about different value systems and their respective priorities in the world, I should not work on the highest priority according to my own values, but on whatever my comparative advantage is amongst all the interventions favored by the value systems of agents interested in multiverse-wide cooperation.
Is the claim (loosely) that we should take actions we think are morally inferior according to us because … there might be other intelligent beings outside of our light cone with different preferences? I would want them to act a little bit more like me, so in turn I will act a little more like them, in a strange game of blind prisoner’s dilemma.
This is obviously hogwash to me, so I want to make sure I understand it before proceeding.

spxtr 16 Sep 2014 22:09 UTC
9 points
in reply to: shminux’s comment on: What are your contrarian views?
I consider him a modern G.K. Chesterton. He’s eloquent, intelligent, and wrong.

spxtr 13 Jun 2014 16:04 UTC
9 points
in reply to: shminux’s comment on: List a few posts in Main and/or Discussion which actually made you change your mind
I was in debate club and considered politics important and worth my time. Within months of reading the mind-killer sequence I became so frustrated with that whole ordeal that I quit, and I haven’t looked back since.

Other than that, yes, you’re right.

spxtr 18 May 2023 16:49 UTC
8 points
2
in reply to: jacob_cannell’s comment on: $250 prize for checking Jake Cannell’s Brain Efficiency
1 nm is somewhat arbitrary but around that scale is a sensible estimate for minimal single electron device spacing ala Cavin/Zhirnov. If you haven’t actually read those refs you should—as they justify that scale and the tile model.
They use this model to figure out how to pack devices within a given area and estimate their heat loss. It is true that heating of a wire is best described with a resistivity (or parasitic capacitance) that scales as 1/L. If you want to build a model out of tiles, each of which is a few nm on a side (because the FETs are roughly that size), then you are perfectly allowed to do so. IMO the model is a little oversimplified to be particularly useful, but it’s physically reasonable at least.
This is just false, unless you are claiming you have found some error in the cavin/zhirnov papers.
No, the papers are fine. They don’t say what you think they say. They are describing ordinary resistive losses and such. In order to compare different types of interconnects running at different bitrates, they put these losses in units of energy/bit/nm. This has no relation to Landauer’s principle.
Resistive heat loss in a wire is fundamentally different than heat loss from Landauer’s principle. I can communicate 0 bits of information across a wire while losing tons of energy to resistive heat, by just flowing a large constant current through it.
It’s also false in the sense that the model makes reasonable predictions.
As pointed out by Steven Byrnes, your model predicts excess heat loss in a well-understood system. In my linked comment, I pointed out another way that it makes wrong predictions.

spxtr 16 Mar 2015 7:49 UTC
8 points
0
on: Rationality: From AI to Zombies
I am impressed. The production quality on this is excellent, and the new introduction by Rob Bensinger is approachable for new readers. I will definitely be recommending this over the version on this site.

spxtr 10 Feb 2015 4:59 UTC
8 points
in reply to: alienist’s comment on: Quotes Repository
The idea is that it’s not specifically for quotes related to rationality or other LessWrong topics.

spxtr 2 Oct 2014 2:41 UTC
8 points
in reply to: ArisKatsaris’s comment on: October 2014 Media Thread
- Agalloch—The Serpent and the Sphere—Excellent black metal. Beautiful melodies, blood-curdling vocals, and atmosphere up the wazoo.
- Behemoth—The Satanist—Excellent death metal. Like most people, my favorite song is Ora Pro Nobis Lucifer. The end of the album is better than the beginning.
Any love for metal on LW?

spxtr 6 Jun 2014 5:35 UTC
8 points
on: Rationality Quotes June 2014
The Patrician took a sip of his beer. “I have told this to few people, gentlemen, and I suspect never will again, but one day when I was a young boy on holiday in Uberwald I was walking along the bank of a stream when I saw a mother otter with her cubs. A very endearing sight, I’m sure you will agree, and even as I watched, the mother otter dived into the water and came up with a plump salmon, which she subdued and dragged on to a half-submerged log. As she ate it, while of course it was still alive, the body split and I remember to this day the sweet pinkness of the roes as they spilled out, much to the delight of the baby otters who scrambled over themselves to feed on the delicacy. One of nature’s wonders, gentlemen: mother and children dining upon mother and children. And that’s when I first learned about evil. It is built in to the very nature of the universe. Every world spins in pain. If there is any kind of supreme being, I told myself, it is up to all of us to become his moral superior.”
- Terry Pratchett

spxtr 21 May 2023 22:18 UTC
7 points
0
in reply to: Ege Erdil’s comment on: $250 prize for checking Jake Cannell’s Brain Efficiency
Maybe I’m interpreting these energies in a wrong way and we could violate Jacob’s postulated bounds by taking an Ethernet cable and transmitting 40 Gbps of information at a long distance, but I doubt that would actually work.
Ethernet cables are twisted pair and will probably never be able to go that fast. You can get above 10 GHz with rigid coax cables, although you still have significant attenuation.
Let’s compute heat loss in a 100 m LDF5-50A, which evidently has 10.9 dB/100 m attenuation at 5 GHz. This is very low in my experience, but it’s what they claim.
Say we put 1 W of signal power at 5 GHz in one side. Because of the 10.9 dB attenuation, we receive 94 mW out the other side, with 906 mW lost to heat.
The Shannon-Hartley theorem says that we can compute the capacity of the wire as $C = B {l o g}_{2} (1 + \frac{S}{N})$ where $B$ is the bandwidth, $S$ is received signal power, and $N$ is noise power.
Let’s assume Johnson noise. These cables are rated up to 100 C, so I’ll use that temperature, although it doesn’t make a big difference.
If I plug in 5 GHz for $B$ , 94 mW for $S$ and $k_{B} (370 K) (5 G H z) \approx 2.5 \times 10^{- 11} W$ for $N$ then I get a channel capacity of 160 GHz.
The heat lost is then $(906 m W) / (160 G H z) / (100 m) \approx 0.05 f J / b i t / m m .$ Quite low compared to Jacob’s ~10 fJ/mm “theoretical lower bound.”
One free parameter is the signal power. The heat loss over the cable is linear in the signal power, while the channel capacity is sublinear, so lowering the signal power reduces the energy cost per bit. It is 10 fJ/bit/mm at about 300 W of input power, quite a lot!
Another is noise power. I assumed Johnson noise, which may be a reasonable assumption for an isolated coax cable, but not for an interconnect on a CPU. Adding an order of magnitude or two to the noise power does not substantially change the final energy cost per bit (0.05 goes to 0.07), however I doubt even that covers the amount of noise in a CPU interconnect.
Similarly, raising the cable attenuation to 50 dB/100 m does not even double the heat loss per bit. Shannon’s theorem still allows a significant capacity. It’s just a question of whether or not the receiver can read such small signals.
The reason that typical interconnects in CPUs and the like tend to be in the realm of 10-100 fJ/bit/mm is because of a wide range of engineering constraints, not because there is a theoretical minimum. Feel free to check my numbers of course. I did this pretty quickly.
What links here?
- Brain Efficiency Cannell Prize Contest Award Ceremony by Alexander Gietelink Oldenziel (24 Jul 2023 11:30 UTC; 145 points)

spxtr

En­tropy and Temperature

Entropy and Temperature