# ­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:** 133
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [December 25, 2023, 11:00pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2643 "2023-12-25T23:00:41Z")
I knew them before they were hot. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 26, 2023, 3:17am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2644 "2023-12-26T03:17:13Z")
The vinyl kept melting ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 28, 2023, 6:48am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2645 "2023-12-28T06:48:40Z")
> **[Supersymmetry](https://xkcd.com/2873/)** > > High-speed collisions at the Baby Park track may support the hypothesis that Daisy is her own evil twin, a theory first suggested by Nintendo in the game Majorana's Mask. ---
**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:** [December 28, 2023, 2:49pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2646 "2023-12-28T14:49:03Z")
Well-played, on that mouseover text. But now I’m wondering… Is there, in fact, an evil twin for Peach but not Daisy? And which princesses correspond to the mu and tau leptons? ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 28, 2023, 11:40pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2647 "2023-12-28T23:40:30Z")
Currently explainxkcd says: " Certain current understandings of the process require that the electron neutrino be an _anti_neutrino, but antineutrinos have not so far been sufficiently confirmed to exist, with some theorising that a neutrino can be its own anti-particle (unlike the neutral neutron, composed of charged quarks, which has the similarly neutral antineutron, composed of oppositely charged antiquarks)." which is wrong about antineutrinos, unless I’m much mistaken. ---
**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:** [December 29, 2023, 12:17am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2648 "2023-12-29T00:17:29Z")
The electron neutrino produced in beta decay of a neutron must be an antineutrino, but the open question is whether an antineutrino is the same thing as a neutrino. Some particles (like the photon) are their own antiparticle, but most (including the neutron and all charged particles) aren’t. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 29, 2023, 8:22pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2649 "2023-12-29T20:22:41Z")
Thanks - I hadn’t realized that was an open question; I knew a photon was its own antiparticle, but thought that neutrinos and antineutrinos were known to be distinct ---
**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:** [December 29, 2023, 8:37pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2650 "2023-12-29T20:37:31Z")
Well, it’s complicated by the fact that all interactions that neutrinos can take part in have this weird handedness thing going on, and that can masquerade as anti-ness. Like, we know that the neutrino produced in regular beta decay is always right-handed, and the neutrino needed as input in a neutrino-induced beta decay must be left-handed, so the neutrino from one beta decay can’t induce another… but do those two particles have any difference other than their handedness? That’s the part we don’t know. And to further explain the mouseover text, the “conventional” model (where neutrinos and antineutrinos are distinct) is called the Dirac model, and the currently-more-popular model (where they’re the same thing except for handedness) is called the Majorana model. Hence why the notion that Daisy is her own evil twin was first raised in Majorana’s Mask. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 30, 2023, 1:11am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2651 "2023-12-30T01:11:56Z")
> **[Iceland](https://xkcd.com/2874/)** > > The HVAC bill for installing the Gulf Stream was enormous. ---
**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:** [December 30, 2023, 1:13am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2652 "2023-12-30T01:13:42Z")
Not as big as the heating bill will be when the Gulf Stream switches off some time in the next 50-200 (?) years. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 2, 2024, 3:18am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2653 "2024-01-02T03:18:45Z")
> **[2024](https://xkcd.com/2875/)** > > It wasn't originally constitutionally required, but presidents who served two terms have traditionally followed George Washington's example and gotten false teeth. I don’t know about enamel lasting that long. If you use fluoride toothpaste, some of the OH’s in the enamel molecules get replacd by F, thereby making them new molecules. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [January 2, 2024, 4:34am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2654 "2024-01-02T04:34:21Z")
Hey! We just covered this! > [@Every Atom in Your Body Is Replaced every 5 Years](https://boards.straightdope.com/t/every-atom-in-your-body-is-replaced-every-5-years/994147): > > Or so I heard Michael from Vsauce say. Checking around it seems to be true: “Studies at the Oak Ridge Atomic Research Center have revealed that about 98 percent of all the atoms in a human body are replaced every year. You get a new suit of skin every month and a new liver every six weeks. The lining of your stomach lasts only five days before it’s replaced. Even your bones are not the solid, stable, concrete-like things you might have thought them to be: They are undergoing constant change. Th… ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 2, 2024, 4:24pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2655 "2024-01-02T16:24:59Z")
> [@DSeid](#): > > We just covered this! Hmmm… is Randall lurking here for ideas? ---
**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:** [January 2, 2024, 4:56pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2656 "2024-01-02T16:56:12Z")
Or maybe he’s not lurking; maybe he’s an active member, and just nobody knows it’s him behind that username. He has cited us occasionally. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [January 3, 2024, 7:07pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2657 "2024-01-03T19:07:02Z")
> **[Range Safety](https://xkcd.com/2876/)** > > The Range Mischief Officer has modified the trajectory to add a single random spin somewhere in the flight, but won't tell us where. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [January 3, 2024, 7:35pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2658 "2024-01-03T19:35:08Z")
When I first saw that page, the tower next to the rocket (I forget what that’s called) was there in the first and third panels, but distinctly missing in the second. Anybody else see that? (Maybe I should have taken a screenshot, but I didn’t. And when I go back to the page now, it’s there in all three panels.) ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 3, 2024, 7:37pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2659 "2024-01-03T19:37:38Z")
> [@thorny\_locust](#): > > the tower next to the rocket (I forget what that’s called) Service Structure. > **[Service structure](https://en.wikipedia.org/wiki/Service_structure)** > > A service structure is a steel framework or tower that is built on a rocket launch pad to facilitate assembly and servicing. > An umbilical tower also usually includes an elevator which allows maintenance and crew access. Immediately before ignition of the rocket's motors, all connections between the tower and the craft are severed, and the bridges over which these connections pass often quickly swing away to prevent damage to the structure or vehicle.\[citation needed\] > During the Space Shuttle p... Although I’ve heard it called just “the tower” in context. And for me, I haven’t seen that cartoon at all before here, so I never noticed any anomalies. But Randall has updated comics after initial publication before. And the explainXKCD trivia section notes the same thing you saw: > **[2876: Range Safety - explain xkcd](https://www.explainxkcd.com/wiki/index.php/2876:_Range_Safety)** > > Explain xkcd is a wiki dedicated to explaining the webcomic xkcd. Go figure. > The tower next to the rocket was also missing from panel 2. ---
**Author:** ![thorny\_locust](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thorny_locust/32/431_2.png) [@thorny\_locust](https://boards.straightdope.com/u/thorny_locust)\ **Post date:** [January 3, 2024, 7:39pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2660 "2024-01-03T19:39:04Z")
Thanks. I think “umbilical tower” is what I was trying, and failing, to think of. ---
**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:** [January 3, 2024, 10:59pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2661 "2024-01-03T22:59:44Z")
How about “gantry”? ---
**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:** [January 3, 2024, 11:04pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/2662 "2024-01-03T23:04:03Z")
The gantry is the moving part of the tower. Another type of tower is the _strongback_, used on the Falcon 9 and probably others. It acts as a tower and provides the propellant umbilicals. But it also raises the rocket from horizontal to vertical. At launch, the umbilicals disconnect and it tilts back a little bit for clearance. It isn’t big or robust enough for manned missions, though. [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=132) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=134)