explain xkcd - User contributions [en]

Talk:2783: Ruling Out

2023-06-02T20:44:52Z

162.158.166.54: reply

Wow. the amount of citation needed tags is excessive. Here's a fun idea, do like that SMBC comic and actually find and give citations. [[Special:Contributions/172.69.70.72|172.69.70.72]] 19:41, 31 May 2023 (UTC)Bumpf
:Definitely. I fixed one (it should have been ''after'' the comma), during some other edits, but was sorely tempted to remove maybe two of them to just keep the funniest one(s). Whichever that(/they) might be. I expect they'll almost all evaporate in a future edit, though, as there's plenty of editting bound to be done. [[Special:Contributions/172.70.90.219|172.70.90.219]] 19:47, 31 May 2023 (UTC)
::Nice work to whomever on that! Xkcd never fails to make me smile if not LOL, and Explainxkcd never fails to teach cool facts. o7 [[Special:Contributions/172.69.134.147|172.69.134.147]] 21:28, 31 May 2023 (UTC)

I'm pretty sure there has been serious scholarship about the habitable zone of some quasars. Let's see.... Here: https://iopscience.iop.org/article/10.1088/1742-6596/2364/1/012057/pdf Not absolutely certain, but absolutely '''not''' ruled out. [[Special:Contributions/172.69.134.24|172.69.134.24]] 20:02, 31 May 2023 (UTC)
:I think that Cueball's scientific team did a study to discount the possibilities of quasars in the habitable zone of a star, not of a habitable zone around a quasar.[[Special:Contributions/172.71.166.249|172.71.166.249]] 20:52, 31 May 2023 (UTC)
::A quasar could exist in the habitable zone of a star, and if it was particularly dim, it wouldn't make the zone inhabitable. There's no minimum brightness for quasars, is there? For example, [https://iopscience.iop.org/article/10.1088/0004-637X/728/1/26] defines quasars in terms of relative magnitude, so I don't see why a tiny black hole with a small but sufficient accretion disk in translunar orbit couldn't qualify. [[Special:Contributions/172.69.134.162|172.69.134.162]] 20:54, 31 May 2023 (UTC)
:::Relative to their ''entire galaxy!'' Fixed explanation. [[Special:Contributions/162.158.166.175|162.158.166.175]] 09:02, 1 June 2023 (UTC)

I don't know how to properly describe the length of time the Moon's orbit of the Earth has been known. If you think that the moon orbits the earth, but you also think the sun, stars, and planets orbit the earth, do you actually have any way to justifiably say that you know that the Moon orbits the Earth? Also, is it worth pointing out the reasons that the moon is such an obvious thing to know about (i.e. its visibility and prominence to the naked eye, its cultural significance,...)?[[Special:Contributions/162.158.174.183|162.158.174.183]] 20:59, 31 May 2023 (UTC)
:Interesting xkcd (sort-of) reference here. Back when What-If questions started being solicited, I sent in something (roughly) like "When trying to justify the original geocentric theory of the solar system, it is said that it had always 'looked like everything went round the Earth'... What would it have looked like if it had always looked like everything, including the Earth, went round the Sun?" ...which I'm pretty sure never got answered. Probably didn't spark enough possible scope for that good old xkcd magic. But I saw plenty of other good stuff, so no regrets on my part. [[Special:Contributions/172.70.162.251|172.70.162.251]] 23:14, 31 May 2023 (UTC)
::I think your question was particularly difficult to answer in any way other than "Everything ''does'' go around the sun. To see what that looks like, look up." I suppose your question (if I'm understanding what you may be looking for) may be stated otherwise as "How different would the movement of our Solar System need to be in order to make it obvious that everything revolves around the sun (to a layperson observer on Earth)"? [[Special:Contributions/172.70.206.194|172.70.206.194]] 14:50, 1 June 2023 (UTC)
:::I don't see much difference between the two ways of putting it (unless you think your one means seeing the 'orbital rails' upon which everything encircles things, or something).
:::Maybe, though, a fairly visible (lunar-sized) satellite of Mars/Venus might be on the edge of discernability (not needing Galileo's assisted view of the Saturnian system, just the kind of patience that raw-eyeballing astronomers used with discerning 'close' stars from each other) thus demonstrating non-geocentrism much earlier and easier and somewhat more undeniable. [[Special:Contributions/172.71.242.128|172.71.242.128]] 17:29, 1 June 2023 (UTC)
::::My proposed question was meant to clarify, so it shouldn't be much different :-) I don't know what the answer would be, but my hope was to clear up that the question wasn't simply "What would it look like if the Earth revolved around the sun?" which is what I had originally interpreted the question as before I decided that it probably wasn't the question that was meant to be asked [[Special:Contributions/172.70.210.90|172.70.210.90]] 17:40, 1 June 2023 (UTC)
:::::Maybe clunkily given here (really we need to see the original Q, not the half-recalled paraphrasing so many years after) but "in order to make it obvious that everything revolves around the [S]un" doesn't look like what you say you first read it as. So to bad writing (capital 'S'!) perhaps add bad reading, I suspect. But we're all fallible. [[Special:Contributions/172.70.91.171|172.70.91.171]] 17:57, 1 June 2023 (UTC)

Y'know, I'm not entirely convinced that "tectonically active black holes" is something that we're actually capable of ruling out [[Special:Contributions/172.68.174.190|172.68.174.190]] 22:33, 31 May 2023 (UTC)
:Even if the black hole is tectonically active, its activity is in one direction only: forward, where you can never catch up to it. The damage is extreme, but it's held safely in the boundary of the singularity. [[Special:Contributions/172.70.130.203|172.70.130.203]] 01:10, 1 June 2023 (UTC)
:I agree; black holes occupy a non-zero volume. Since the space below the event horizon has depth, I don't see any reason why the arrangement of mass inside could not shift. Indeed, the evidence of gravitational irregularities affecting their accretion discs, seems like evidence of nonhomogeneity within that volume. I think black holes probably ''do'' have "tectonic" activity!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 16:27, 2 June 2023 (UTC)
::Counting all the volume within the event horizon (infinite, due to the infinite curvature), the density wouldn't support tectonics. The acretion disc is affected by what is on the verge of falling in (minus what has ''actually'' fallen in which just acts as a hairless 'lump'). Not sure you can call what happens in the disc as 'tectonics'... No pressures from below (the opposite) it's just interactions of decaying orbits. [[Special:Contributions/172.71.178.137|172.71.178.137]] 18:43, 2 June 2023 (UTC)

Did anyone else see the connection between this comic and the NASA briefing yesterday on UAPs (Unidentified Aerial Phenomena, their term for UFOs)? In the briefing they discussed that the approach they'd need to take is one of ruling out everything else instead of saying for certain that "this is a UAP". I think that's the entire intent of this joke - to comment on the NASA briefing. [[Special:Contributions/162.158.175.113|162.158.175.113]] 11:50, 1 June 2023 (UTC)

Strictly speaking, the first two classes of object listed couldn't be 'ruled out' by a study, since they're non-existent by definition, and therefore can't be subject to any meaningful proof or disproof.[[Special:Contributions/172.71.242.87|172.71.242.87]] 15:58, 1 June 2023 (UTC)
:While exoplanets in our solar system are non-existent by definition, ruling out earth-like stars does need some study to prove that earth is neither star nor sufficiently star-like. Note that you CAN find Jupiter-like stars. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 20:55, 1 June 2023 (UTC)
:I think part of the joke is that the "study" is just a scientist saying "Yup, that can't exist." [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 01:19, 2 June 2023 (UTC)

I think the entire point of including “habitable-zone quasars” was completely missed so far. It’s not that a quasar can’t have a habitable zone near it, even if that’s unlikely, nor is it that a quasar couldn’t be in a star’s habitable zone. It’s that SO WHAT IF IT IS? You couldn’t inhabit a quasar regardless what ‘zone’ it was in. If you were looking for a new home, you’d look at homes within a price range you could afford (not too expensive, but not TOO cheap). Looking for a quasar in the habitable zone of a star would be like asking a realtor to show you an active volcano within your price range. [[Special:Contributions/172.69.33.155|172.69.33.155]] 20:13, 1 June 2023 (UTC)
:Well ... "active volcano within my price range" is exactly what traditional Evil Overlord asks for. The smarter ones ask for volcanos which are non-active but can be made looking active. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 20:55, 1 June 2023 (UTC)
::Volcano?!? Most of us can't even afford a sinkhole.
::[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 16:31, 2 June 2023 (UTC)
:::You need to up your evil overlord game, Zarquon. [[Special:Contributions/162.158.166.54|162.158.166.54]] 20:44, 2 June 2023 (UTC)

Given the text at the bottom of the drawing, this also sounds like a reference to Hempel's paradox (aka raven paradox) https://en.m.wikipedia.org/wiki/Raven_paradox
[[User:Gisbert|Gisbert]] ([[User talk:Gisbert|talk]]) 21:01, 1 June 2023 (UTC)

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2023-05-25T22:59:28Z

162.158.166.54:

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