# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 169
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [September 6, 2024, 6:55pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3363 "2024-09-06T18:55:15Z")
> [@Lumpy](#): > > Weren’t they going to define the kilogram as the mass of an exact countable number of atoms of silicon in a specially prepared sphere? What happened with that? As @Civil_Guy said, the kilogram was redefined in terms of fundamental constants, using a device called a [Kibble balance](https://www.nist.gov/si-redefinition/kilogram-kibble-balance). In the run-up to the redefinition, the [“counting atoms” approach](https://www.nist.gov/si-redefinition/kilogram-silicon-spheres-and-international-avogadro-project) was a leading contender. Despite the Kibble/Planck-constant approach ultimately being selected, resolving discrepancies between the two techniques is an active area of research. > **[One of the World’s Roundest Objects Is Helping to Build a Better Mass...](https://www.nist.gov/blogs/taking-measure/one-worlds-roundest-objects-helping-build-better-mass-measurement)** > > Different countries' approaches can lead to different definitions of the kilogram. But NIST is working with our international partners to see how we can close those tiny gaps. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [September 6, 2024, 7:25pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3364 "2024-09-06T19:25:57Z")
> [@Alessan](#): > > all volcanic rock can also be called lava You _could_, but we (geologists) generally prefer more specificity than that if possible. Like “basalt” or “andesite”. > [@Chronos](#): > > Not all igneous rocks are lava. “igneous” and “volcanic” aren’t synonyms. > [@Lumpy](#): > > I believe the term is “magma”. Magma is what it’s called when it’s still deep underground. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [September 6, 2024, 7:40pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3365 "2024-09-06T19:40:28Z")
> [@dasmoocher](#): > > …As the saying goes: “The man with one watch always knows what time it is; the man with two is never sure.” That’s why with inertial (i.e. dead-reckoning) navigation you might find it advisable to use _three_ instruments and go with majority rule. If all three disagree (or if one fails) than it’s clear you have no idea where you are and it’s time to determine your position using another method entirely (like GPS) and recalibrate the inertial instruments. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [September 7, 2024, 12:39am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3366 "2024-09-07T00:39:49Z")
> [@robby](#): > > If all three disagree (or if one fails) than it’s clear you have no idea where you are a I know you’re summarizing mightily and only partly serious. I’d say it more like If all 3 are seemingly working normally they’ll still disagree some. You assume you’re somewhere in/near the triangle formed by the 3 fixes. The smaller and more equilateral the triangle, the happier the nav officer is. If two agree to typical tolerances and the third is a long way away, or stone dead, strike an ellipse around 2 two positions you have. But with a larger than usual confidence interval. And start worrying. If they’re each in major disagreement w the other(s), you are well and truly lost until you come up w some alternate means to fix your position. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [September 7, 2024, 2:47am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3367 "2024-09-07T02:47:52Z")
> **[Water Filtration](https://xkcd.com/2982/)** > > You'd think the most expensive part would be the quark-gluon plasma chamber, but it's actually usually the tube to the top of the atmosphere to carry the cosmic rays down. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 7, 2024, 2:50am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3368 "2024-09-07T02:50:27Z")
I recommend avoiding partially hydrogenated water. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [September 7, 2024, 2:51am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3369 "2024-09-07T02:51:14Z")
After a steady online diet of watching preparedness videos, this hurts my brain. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [September 7, 2024, 3:01am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3370 "2024-09-07T03:01:20Z")
After thinking about it, I’m surprised there wasn’t a reverse transcriptase step. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 7, 2024, 3:05am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3371 "2024-09-07T03:05:23Z")
I demand isotope separation. I only drink water made from _pure_ 16O. Anything else would… sap and impurify my precious… bodily fluids. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [September 7, 2024, 3:52am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3372 "2024-09-07T03:52:41Z")
I did chuckle that after exposure to the neutron source, it’s now an _activated_ carbon filter! 😛 ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [September 7, 2024, 11:41am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3373 "2024-09-07T11:41:52Z")
> [@Dr.Strangelove](#): > > I recommend avoiding partially hydrogenated water. Overly hydrogenated water is also bad. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [September 7, 2024, 12:59pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3374 "2024-09-07T12:59:26Z")
> [@LSLGuy](#): > > > [@Dr.Strangelove](#): > > > > I recommend avoiding partially hydrogenated water. > > Overly hydrogenated water is also bad. As is overly oxygenated water. Not so much the kind with oxygen gas dissolved in it (which is fine), but the kind with an extra oxygen atom in each molecule (aka hydrogen peroxide). ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 7, 2024, 1:03pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3375 "2024-09-07T13:03:02Z")
> [@Dr.Strangelove](#): > > I recommend avoiding partially hydrogenated water. Sure, but Santa does recommend it. Why should we take your word over his? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [September 7, 2024, 1:09pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3376 "2024-09-07T13:09:13Z")
> [@robby](#): > > > [@LSLGuy](#): > > > > > [@Dr.Strangelove](#): > > > > > > I recommend avoiding partially hydrogenated water. > > > > Overly hydrogenated water is also bad. > > As is overly oxygenated water. Not so much the kind with oxygen gas dissolved in it (which is fine), but the kind with an extra oxygen atom in each molecule (aka hydrogen peroxide). Welp. I’m embarrassed to admit I was aiming for hydrogen peroxide myself. I interpreted @Dr.Strangelove’s description backwards, then wrote the opposite trying to be clever. Well, the whoosh is on me. Turns out water is H2O, not O2H. _Who knew?!_ 🤦‍♂️ ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [September 7, 2024, 1:41pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3377 "2024-09-07T13:41:26Z")
\mathrm{H\_3O^+} isn’t palatable in very large quantities, either ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [September 7, 2024, 1:51pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3378 "2024-09-07T13:51:09Z")
> [@abcdefghij](#): > > \mathrm{H\_3O^+} isn’t palatable in very large quantities, either Good one! (And nice formatting! I’ve not seen that method before.) Turns out you were right after all, @LSLGuy. ---
**Author:** ![dasmoocher](https://avatars.discourse-cdn.com/v4/letter/d/dbc845/32.png) [@dasmoocher](https://boards.straightdope.com/u/dasmoocher)\ **Post date:** [September 7, 2024, 2:04pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3379 "2024-09-07T14:04:25Z")
> [@LSLGuy](#): > > Turns out water is H2O, not O2H. _Who knew?!_ It’s scarier than you may know. Oldie but goodie (gives a brief history of DHMO trolling): [Who First Alerted the World to the Dangers of Dihydrogen Monoxide?](https://www.youtube.com/watch?v=zIvrxqQ6beI) ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [September 7, 2024, 2:16pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3380 "2024-09-07T14:16:49Z")
How did the chemist die? When his friend ordered H2O at the bar, he ordered H2O too. ---
**Author:** ![Q.Q.Switcheroo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/q.q.switcheroo/32/5713_2.png) [@Q.Q.Switcheroo](https://boards.straightdope.com/u/Q.Q.Switcheroo)\ **Post date:** [September 7, 2024, 3:38pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3381 "2024-09-07T15:38:20Z")
Billy was a chemist’s son But Billy is no more For what he thought was H2O Was H2SO4 ---
**Author:** ![digs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/digs/32/14889_2.png) [@digs](https://boards.straightdope.com/u/digs)\ **Post date:** [September 7, 2024, 6:42pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/3382 "2024-09-07T18:42:15Z")
> [@abcdefghij](#): > > the kilogram was redefined in terms of fundamental constants… [sigh] But that still doesn’t change the fact that I have four extra ones around my waist… [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=168) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=170)