Talk:3085: About 20 Pounds

Wow - first here! I can't help thinking 'about 20 pounds' could be exactly 10 kg! 0r even one Newton?! RIIW - Ponder it (talk) 05:50, 6 May 2025 (UTC)

"One Newton" and "10 kg" are totally different things. "10 kg" would cause 1 Newton of gravitational force if you were in a world with about 1% of Earth's gravity, though. --172.69.109.86 09:53, 6 May 2025 (UTC)

Oops! In my rush I should have checked and put 100 Newtons. I was relying on 10kg being about 22 pounds, or rather the other way around, and then a particle having mass not weight and Science using Metric units. Apologies. RIIW - Ponder it (talk) 11:41, 6 May 2025 (UTC)

(Moved your reply up a bit. You seemed to respond to "20 pounds are...", below, and split their timestamp signature from their message. And forgot to sign properly, at first, so I got edit-conflicted twice whilst trying to post myself and correct your initial error. Please take a bit more care, everybody. 172.70.163.53 11:52, 6 May 2025 (UTC))

20 pounds are approximately 9.072 kg, so not exactly 10 kg (in fact, it rounds to 9). 172.70.134.55 10:02, 6 May 2025 (UTC)

That's the wrong way to think about it. "Exactly 10kg" is "exactly 22.0462lbs", but that (to the nearest single significant figure) is legitimately "about 20lbs". See any given step in 2585: Rounding, especially where that 'disagrees greatly' with an adjacent step.

As with any Oracle (that's worth its omphalos), it may be giving an entirely true answer which nevertheless is deliberately phrased as ambiguous and misinterpretable, the possible supernatural complement to the 'exact words' genie contract. As with the 2741: Wish Interpretation genie, the Oracle may slip into less "unhelpfully helpful" mode immediately after, though for different reasons. However, "burritos are pretty good" also suggests that there's some other thing that is more good, so — again — it's giving a sufficient response to what they (now) should do, but not a perfect one.

As I write, the explanation (probably needs a general rewrite) doesn't mention anything about the burritos except as title text, or I would have ensured the famed exact-words/vague-detail was noted in that bit. (Shorter than here.) 141.101.98.82 11:46, 6 May 2025 (UTC)

172.70.134.55 10:02, 6 May 2025 (UTC) Though I don't think it at all merits being described as a reference, I am minded of the The Usenet Oracle (at least when I knew of it). Though, if it was to be a deleliberate shout-out, I'd expect a few more actual in-jokes. 172.70.86.130 06:10, 6 May 2025 (UTC)

I bet Randall is in some kind of force-interaction-related, What-if-induced rabbit hole right now (or has been at the time of writing). Wondering what the next comic will be about. 172.71.144.175 08:39, 6 May 2025 (UTC)

"Nature of ... 20 pounds" is a reference to the koan "A monk asked Tozan, 'What is the nature of Buddha?' He replied, 'Three pounds of flax.'" Someone can add this to the explanation. 172.70.111.115 08:57, 6 May 2025 (UTC)

There is a similar story in the Principia Discordia. When asked what is the meaning behind POEE, a Discordian cabal, Malaclypse the younger answered "five tons of flax." FlavianusEP (talk) 16:30, 6 May 2025 (UTC)

"something that doesn't interact with electromagnetism cannot be 'seen', as photons will pass through it completely unaffected": is this supposed to be true ? I thought photons interacted with gravity, and even the phrase before states that gravity is believed to affect everything. 172.68.151.93 09:17, 6 May 2025 (UTC)

We can infer Dark Matter (and, for that... *ahem* ...matter, also Dark Energy) from what the photons in the universe are telling us that does not look anything like what 'light(-interacting) matter' should be doing. As with some searches for black holes (most particularly, when the theory is that the unseen mass of the universe is a lot of small black holes drifting in the void, not acreting enough to create secondary visible effects), whether or not light is being gravitationally lensed by things (that we cannot directly see) is part of the way that we're narrowing down what-and-where DM is.

And, I think, currently it seems to be considered that it's residing in a webwork of DM tendrils, at extragalactic (indeed, cosmological) scales, such that where the tendril cross is where they draw 'normal' matter together enough to be any given galaxy. But that's in an "explains all(/many) known facts" way, and might yet be incorrect. e.g. if there's side-dimensions (equally undetectable, at least visually) that change the inverse-square dropoff of gravity at large enough scales to govern galactic rotation rates by just enough to fit observations, or we have some other misunderstanding/scientific blind spot that further study may correct.

Or, in short, think Brownian Motion. We can't see a handful of air molecules (not by normal, even microscope-enhanced, human vision), they might as well be invisible. But, by what we see of more visible particles, suggests that they exist as something. Conversly, the æther, a proposed medium for light, was thought to exist in a similar all-pervasive manner (insofar as trivial human experience, though less physically 'interactive' than wind), but deeper checks (as to whether its effects on light were as they should have been) dismissed it as a possible concept.

Depending upon interpretation of the comic (I originally read it as "all dark-matter particles are ~20lbs in mass WIMPs/nano-MACHOs/whatever", but it seems that others take it as "all of dark-matter particles is a single ~20lbs mass particle"; and that's make the oracle-invokers' attitudes more logical, if not the universe), there actually being Dark Matter, but it being just 20lbs of 'something' somewhere in the whole universe, makes it a needle in a galactic-supercluster-sized haystack.

Detecting that would be difficult in the extreme. Even if it's somehow within a few hundred metres of the experimenters. There are ways to observe the movements of small masses at small distances, but when you don't even have a clue if it exists (or is moving/has moved, and how), it's fairly hopeless. Gravitational lensing of light would be impractical at such distances/masses. LIGO may be very clever, insofar as merging high-mass objects at long distances, but not really for this. Event Horizon Telescope's ability to see a black hole('s accretion disk) via Very Long Baseline Interferometry is also totally useless here.

I think I'd also settle for the burritos, given that certainty that I wasn't going to find what I'm looking for via any obvious route. (Assuming I couldn't ask the Oracle to show me the Dark Matter, rather than just answer questions about it. And noting that, if not for the indicated progression of the conversation, I might have assumed the oracular voice were really from the pentagram (more usual for demonology, not oracularities!) and that the dark blob was the 20lbs of Dark Matter. Which, of course, it does not deny, so maybe my headcan[n]on is that the summoned Oracle is the DM, being deliberately evasive, and successfully so. That would satisfy it being both that which Ponytail seeks, and the entity of which Ponytail summons in order to seek it! Cueball, however, is currently just seeking food, which (one assumes) the DM-slash-Oracle is not.) 172.68.229.25 12:48, 6 May 2025 (UTC)

My physics skills are rusty but 20 pounds is much more than the Planck mass. Doesn't this imply that Randall's dark matter particles would be black holes? 172.68.243.107 10:05, 6 May 2025 (UTC)

Yes, you are right that 9 kg is about 417,000,000 times more than the Planck mass (21.76 μg), but no, that doesn't imply that 9 kg dark matter particles would be black holes, for that particle can be larger than 417,000,000 Planck lengths (1 Planck length is c. 1.616255×10^–35 m, so above 7 rm, this particle would not collapse into a black hole). 172.68.245.81 10:23, 6 May 2025 (UTC)

Since it's Star Wars day and the 20 lbs. reference would be causing a massively large amount of mass, would it be safe to say that they "sense a great disturbance in the force?" 67.84.20.42 10:20, 6 May 2025 (UTC)

Back in 2005, when the kg was an actual object's mass, there was an article about what a five pound (~2.268 kg) electron is, but it was deleted, for it is a "trivial result of special relativity". 172.68.245.81 10:23, 6 May 2025 (UTC)

Since pounds are a measure of weight, and weight is a measure of the gravitational attraction between an object and its "planet", what is the reference planet that is being used to define the weight of the Dark Matter particle?
Should we assume that Earth's surface is being used as the reference, even though we have no measurements that suggest DM particles are around us, and no reason to assume that the particles would even notice that Earth has a "surface"?
If Randall wanted to use mass, then he should have used the imperial unit of slug, but I suppose saying that a DM particle is 0.62162 slugs might not give the readers quite the same impression as using 20 pounds. Galeindfal (talk) 13:38, 6 May 2025 (UTC)

I might be missing some humour here, but the pound is actually a measure of mass, just like the gram, so it doesn't vary from a planet to another. You might have fallen prey to the second paragraph of the wikipedia article about the pound-force, which states: 'Pound-force should not be confused with pound-mass (lb), often simply called "pound"' 172.71.127.160 14:35, 6 May 2025 (UTC)

Is this, by chance, the Internet Oracle? 104.23.187.126 13:49, 6 May 2025 (UTC)

I don't see anything like the pentagram with candles at its web site. The comic seems more like they're summoning a daemon. Barmar (talk) 14:10, 6 May 2025 (UTC)

Any idea where Randall came up with "20 pounds"? Why not 19 or 21 (blackjack!)? Why not use Newtons (too figgy?)? Only thing I can think of is that, in America at least, many people think they are "about 20 pounds overweight." I think that's too much of a stretch (pants???) to be the answer here. 172.68.27.170 14:07, 6 May 2025 (UTC)

I think it's just humorous, adding to the imprecision / casualness of "about 20". Imperial measurements feel "less scientific" than metric. 162.158.146.124 16:26, 6 May 2025 (UTC)

The amount of people confusing mass and weight/force in this thread is pretty disappointing for an xkcd forum. You can't convert pounds into Newtons. 162.158.172.143 16:38, 6 May 2025 (UTC)

I don't think it's accurate to say (as the explanation does right now) that 20 lbs is too little to detect through gravitational interaction. Throwing some numbers together: a 20lbs-sphere of Osmium, the heaviest stable element, is about 4.5cm in radius. If a 20lbs point mass flies by just above the surface of that sphere, it would generate a gravitational force of about 2.5 micronewtons (hooray for Gauss's theorem). That's the weight of a few grains of salt - small, but definitely detectable. If they're all really really fast, or there's always lots of them around at any given time or something, that might wash out any measurements (someone more knowledgeable about dark matter can probably comment what the expected velocity and flux density of 20lbs-dark-matter-particles would be where we are). But in principle, rather measurable! 162.158.172.142 17:00, 6 May 2025 (UTC)

"A particle that interacts with nothing except gravity, could only be detected by a gravitational telescope." -- Detected by a whatnow? Is that a thing which exists? Google had nothing for "gravitational telescope" when I searched for it. Additionally, are there any theoretical physicists out there who can weigh in on how plausible the "20 pound particle that doesn't interact with anything else" theory is? MeZimm (talk) 19:33, 6 May 2025 (UTC)