1440: Geese

This forum is for the individual discussion thread that goes with each new comic.

Moderators: Moderators General, Prelates, Magistrates

User avatar
ilduri
Posts: 43
Joined: Thu Nov 29, 2012 7:59 am UTC
Location: Canada

Re: 1440: Geese

Postby ilduri » Thu Oct 30, 2014 12:09 am UTC

Himself wrote:Galaxies look smudge-like. From what I understand astronomers referred to them as clouds before they figured out what they were.

Before we figured out what galaxies were, the term nebula included both galaxies and (what we today call) nebula. Nebula means "little cloud" in Latin.
"Butterflies and zebras and moonbeams and fairytales"
she/her

User avatar
Klear
Posts: 1965
Joined: Sun Jun 13, 2010 8:43 am UTC
Location: Prague

Re: 1440: Geese

Postby Klear » Thu Oct 30, 2014 12:27 am UTC

M31 is still sometimes called the Andromeda nebula...

I remember seeing it with naked eye once, and I thought I could see even the disc shape. Both my sight and light pollution has gotten worse since then though.

User avatar
ilduri
Posts: 43
Joined: Thu Nov 29, 2012 7:59 am UTC
Location: Canada

Re: 1440: Geese

Postby ilduri » Thu Oct 30, 2014 3:17 am UTC

Fun fact: the Andromeda galaxy's angular dimensions are several times larger than the full moon. It's just not nearly bright enough for us to be able to see the whole thing without special tools.
"Butterflies and zebras and moonbeams and fairytales"
she/her

Mikeski
Posts: 1096
Joined: Sun Jan 13, 2008 7:24 am UTC
Location: Minnesota, USA

Re: 1440: Geese

Postby Mikeski » Thu Oct 30, 2014 4:32 am UTC

ilduri wrote:Fun fact: the Andromeda galaxy's angular dimensions are several times larger than the full moon. It's just not nearly bright enough for us to be able to see the whole thing without special tools.

I grant you +1 Internet for following "Fun fact:" with an actual fun fact.

To maintain the balance, I penalize Dr What -1 Internet for a misformatted comic-thread post, with no commentary of his own.

User avatar
Pfhorrest
Posts: 5392
Joined: Fri Oct 30, 2009 6:11 am UTC
Contact:

Re: 1440: Geese

Postby Pfhorrest » Thu Oct 30, 2014 5:35 am UTC

I award Dr What one Internet for having an awesome avatar, and another Internet for having a punny username.

Also, a googleplex Internets to Gryffindor because why the fuck not.

Welcome to Hogwarxkcd, where the facts aren't made up but the points still don't matter.
Forrest Cameranesi, Geek of All Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
The Codex Quaerendae (my philosophy) - The Chronicles of Quelouva (my fiction)

User avatar
Neil_Boekend
Posts: 3220
Joined: Fri Mar 01, 2013 6:35 am UTC
Location: Yes.

Re: 1440: Geese

Postby Neil_Boekend » Thu Oct 30, 2014 6:59 am UTC

Himself wrote:
Spoiler:
Garnasha wrote:
Himself wrote:Yes. That misconception is a bit of a pet peeve. Kinda funny that, given how big the universe is, that people would actually overestimate the distance between things.
Actually, I have another theory about that. What if their sense of distance isn't off, having quite accurately grasped that the distances involved are huge, but they then ignore the word 'light year"* and go on to underestimate the speed of light since they've been told that it's "very fast, but not as instant as it seems". Light is FAST. Speed of causality is finite but not easily imagined.

And I think photons would disagree with the bit about their travel not being instant: as I understand special relativity (barely, did a unit about it in high school) it would seem to me photons observe the universe as standing still in time and being perfectly flat (with the plane perpendicular to the direction of travel). And infinitely heavy, I think? Or at least those are limit cases, as v approaches c from below, for a function that is ill-defined for v=c.

Ps. And regarding sense of distance being off or not: I must admit my own sense of distance just gives up for stellar distances, unless I start thinking in "light times" as the base unit of distance, at which point all my reference distances effectively become 0, so I still have no sense of how big space really is. Rules of thumb: however vast you think interstellar space is, it's bigger than that, and however fast you think light is, it's faster than that. And those cancel out. And I wonder how they compare to supernovae.

*hey, a front yard a yard long is really tiny, feet a foot long are huge, and taking a thousand (mille) paces will take you half a mile forward. Imperial system users are USED to units, especially of distance, not making the foggiest bit of sense etymologically. The metric system has it better as far as I know: none of their units seem to refer to any object-derived distance/volume/time/force/energy in their etymology at all.

*edit*: dammit, ninja.
Gil-Galad wrote:
Himself wrote:Yes. That misconception is a bit of a pet peeve. Kinda funny that, given how big the universe is, that people would actually overestimate the distance between things.

They just underestimate the speed of light. Everything in Space is huge, so a couple (hundred) lightyears doesn’t sound much.


Perhaps it is the speed of light they underestimate. Either way, I'd be interesting to see how many people think that the stars we see are millions of light years away, or that Mars is light years away.

I stumbled across this image a while back.
Image
I found it interesting that everyone seemed to comment on how a light year is a unit of distance, not time, and did not seem to notice the few orders of magnitude of error.

If I may modify the rules of thumb a tad to include the age of stars:
Rules of thumb: however vast you think interstellar space is, it's bigger than that. However fast you think light is, it's faster than that. However long you think stars live, it's longer than that. And those can cancel out in any combination.

The star you wish upon may be dead for a hundred years. It may also live another billion years. That really depends on the star.
Same with the speed of light and the vastness of interstellar space. In the case of some objects on our night's sky it does indeed cancel out. In case of some other is really doesn't. The vastness of space just wins in some cases.

Garnasha wrote:Other subtopic: anyone here in favour of replacing km/h with nc (nanolights)? So a 120km/h highway becomes 110nc, or our nutjob minister of Infrastructure, who wants to raise the speed limit to 130km/h (like we don't have enough pollution and accidents yet, not to mention driver fatigue), could just get her way by changing 120 km/h to 120nc. And sound would move at roughly 1µc(microlight).

I am all for that due to the awesomeness of it.
I am all against it because 927
Mikeski wrote:A "What If" update is never late. Nor is it early. It is posted precisely when it should be.

patzer's signature wrote:
flicky1991 wrote:I'm being quoted too much!

he/him/his

User avatar
Coyne
Posts: 1100
Joined: Fri Dec 18, 2009 12:07 am UTC
Location: Orlando, Florida
Contact:

Re: 1440: Geese

Postby Coyne » Thu Oct 30, 2014 7:25 am UTC

orthogon wrote:
CharlieP wrote:
quolnok wrote:A few hundred yards? that doesn't seem very precise. For a start, are we talking about front yards, back yards or grave yards?


My first thought was "why yards, and not feet?". As somebody who prefers SI measurements, I'm yet to figure out what the rule is.

Length of a tapered drinking vessel with a bulb at one end: 1 yard
Height of a tall person: 6 feet
Length of a football field: 100 yards
Length of a Nimitz-class aircraft carrier: 1,092 feet
Length of a two-lap running race: 880 yards
Altitude of Alan Eustace's recent jump: 135,906 feet

I speculated about this in another thread, but there's definitely a tendency to use different units for quantities that have the same dimensions when those physical quantities are felt to be qualitatively different; even the most rigid adherent of SI would hesitate to use the Joule as a unit of torque, for example.

Orientation is one distinguishing factor. For human beings living in a strong gravitational field, vertical distances are completely different to horizontal distances. I would generally (when in an imperial frame of mind) only use yards and miles for horizontal distances in the context of travel; vertical distances are measured in feet. Yards of Ale and the Mile High Club are interesting examples: the former is probably partly because it's held horizontally and partly to emphasize the extraordinary size of the vessel by deliberately using the "wrong" unit; the Mile High Club is probably another example of the "wrong unit".

Objects, natural or man-made, are generally measured in feet rather than yards, hence the aircraft carrier. I guess a football pitch is conceived more in terms of distances that the players have to travel marked out on the ground, rather than as an artefact or object.

I don't expect to come up with a definitive set of rules - many of these things are probably arbitrary convention - but it isn't completely random either.

One final point is that yards aren't very useful when you want to provide a fractional part: you can say 6ft 4ins, but 2yds 4ins? 2 yds 0 ft 4 ins?


I think there are several factors involved orientation, convenience, precision, tradition, and connotation, to name a few.

Speculations:

  • Length of a tapered drinking vessel with a bulb at one end: 1 yard From a yardstick, the traditional ruler for more than 1 foot.
  • Height of a tall person: 6 feet When people are very young, they are measured in inches. That changes at some point...see belo.
  • Length of a football field: 100 yards 100 has a nice connotation, I expect.
  • Length of a Nimitz-class aircraft carrier: 1,092 feet Yard is too inaccurate, even at that length; off by 1 yard is off by 0.3%
  • Length of a two-lap running race: 880 yards Many races are much shorter and came to be denoted in yards. 880? Exactly half a mile, of course.
  • Altitude of Alan Eustace's recent jump: 135,906 feet I'll buy your speculation on vertical distance for this. But I note that altitudes such as the space station are often given in miles.

Essentially, a lot of this thinking derives from some software I worked out that translates age to human terms. Every human age can be translated to days, but for example when have you last hear it said that someone is 21,204 days old? What I was trying to do was come up with rules to specify which unit should be used for "common nomenclature", and this is what I came up with:

  • 1 day old to 6 days old
  • 1 week old
  • 7 days old to 10 days old (when did you ever hear of a 15-day-old or 21 day old baby?)
  • 2 weeks, 3 weeks
  • 1 month old
  • 4 weeks to 7 weeks old
  • 2 months old
  • 9 weeks old to 11 weeks old
  • 3 months old to 11 months old
  • 1 year old
  • 13 months to 17 months, approximately
  • 1½ years old, 2, 2½, 3, 3½, 4, 4½
  • ...but then the halves are dropped; I've heard 4½, but not 5½; after that it just goes by year: 5, 6, 7, 8...

...and I'm not sure I got it right (it was never actually implemented) because I'm quite sure someone could dispute these. In summary, the rules are highly arcane and human...not necessarily making straightforward logical sense. And, like so many things a balance of human factors: number of syllables (convience); listener needs to know (accuracy); how does it make me feel to say it (21,204 days is just silly); what sounds good (connotation); what have I heard other people use (tradition).

If you want a real reason, expect to spend a lot of time on research...
In all fairness...

User avatar
Klear
Posts: 1965
Joined: Sun Jun 13, 2010 8:43 am UTC
Location: Prague

Re: 1440: Geese

Postby Klear » Thu Oct 30, 2014 11:07 am UTC

Coyne wrote:Every human age can be translated to days, but for example when have you last hear it said that someone is 21,204 days old?


Close enough.

Which reminds me that I missed my 10,000th day celebration three months ago =(

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 26738
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1440: Geese

Postby gmalivuk » Thu Oct 30, 2014 12:47 pm UTC

I just passed my billionth second, myself, which is the last power of ten I'll have in any of the standard lengths of time unless I make it to my thousandth month in my 80s.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)

Plutarch
Posts: 103
Joined: Fri Apr 17, 2009 10:29 am UTC
Location: London, UK

Re: 1440: Geese

Postby Plutarch » Thu Oct 30, 2014 1:18 pm UTC

I like geese. In Scotland they guard whisky warehouses.

User avatar
mathmannix
Posts: 1445
Joined: Fri Jul 06, 2012 2:12 pm UTC
Location: Washington, DC

Re: 1440: Geese

Postby mathmannix » Thu Oct 30, 2014 5:09 pm UTC

gmalivuk wrote:I just passed my billionth second, myself, which is the last power of ten I'll have in any of the standard lengths of time unless I make it to my thousandth month in my 80s.


You could look forward to your thousandth fortnight in a few years...
I hear velociraptor tastes like chicken.

jpvlsmv
Posts: 85
Joined: Wed Jan 09, 2013 9:43 pm UTC

Re: 1440: Geese

Postby jpvlsmv » Thu Oct 30, 2014 7:54 pm UTC

Boson Collider wrote:The 1g gravity example you mentioned is kind of interesting, and actually illustrates how the geometry of a black hole works. The horizon would be an infinitely long radial distance below you, so if you lived on a 1g shellworld around a black hole and dropped your watch into the black hole, it would fall down a roughly corresponding distance radially. But time is equally compressed, so the clock would get forzen in time and never show an hour beyond a certain point. From it's point of view, it would reach the horizon in a finite amount of time. From the point of view of someone standing on the shell, it would on the other hand never reach the horizon in a finite of time since the horizon is infinitely far down.


Am I right that to someone standing on the shell, the clock would also appear increasingly redshifted when I look down at the clock? If we drop the clock in so that (from its frame of reference) it reaches the horizon at 5:00, I think we would see a redder and redder clock running slower and slower at 4:30, (woohoo, got a job watching the clock) 4:45, 4:52... 4:58, 4:59, 4:59:59 (ok, I'm ready to retire now), 4:59:59.9, (passing infrared) 4:59:59.99, (grandkids die of old age) 4:59:59.999, ... etc.

Eventually, wouldn't the clock be visible only in far-longwave-radio and read 4:59:59.99999999999999999 and our shellworld's protons all be decayed?

User avatar
gmalivuk
GNU Terry Pratchett
Posts: 26738
Joined: Wed Feb 28, 2007 6:02 pm UTC
Location: Here and There
Contact:

Re: 1440: Geese

Postby gmalivuk » Thu Oct 30, 2014 8:55 pm UTC

Even an infalling thing that magically didn't increase the black hole's radius (which any mass or energy falling in must do, so good luck finding something with neither mass nor energy to make a clock out of), the redshift would increase more quickly than that and you'd see its last photon within a much shorter time than that.

But in reality, while the calculations are quite complicated for the precise shape of an event horizon as a bit of mass falls in asymmetrically, in the end the event horizon must expand somehow, and must do so in finite coordinate time, and that means expanding past the point it looks like your infinitely redshifted clock should have stopped. So even from the outside, things really would fall into the black hole in finite time.
Unless stated otherwise, I do not care whether a statement, by itself, constitutes a persuasive political argument. I care whether it's true.
---
If this post has math that doesn't work for you, use TeX the World for Firefox or Chrome

(he/him/his)


Return to “Individual XKCD Comic Threads”

Who is online

Users browsing this forum: No registered users and 35 guests