Wikipedia:Reference desk/Archives/Science/2022 June 22

= June 22 =

When is a group too large?
Is there a scientific study on the maximum size a group of people can be in order to organize themselves?--2A02:908:422:9760:3487:FE15:1D22:12D6 (talk) 20:10, 22 June 2022 (UTC)


 * There's Dunbar's number (about 150), and here's some academic paper which is trying to back that number up, by looking at the size of people's Christmas card mailing lists. Card Zero  (talk) 21:17, 22 June 2022 (UTC)
 * While I'm not aware of specific scientific studies, an immediate issue is to give an operational definition of self-organization in a sociological sense. It is not at all evident that self-organization requires that every individual member of the group knows who each person is and how each person relates to every other person in the group. Viewing the group abstractly as a dynamic system, the evolution of internal relations may bring the system to a relatively stable equilibrium, or it may remain chaotic. I suppose – without specific theoretical backing – that much depends on whether the group already shares a sense of a common destiny, a common purpose or even a vision grounded in equality, or whether it is "each to their own" from the beginning. I further suppose that one can train people in efficient methods of self-organization, so that a much larger group of people, if many have received such training, will be able to readily organize themselves than without such training. --Lambiam 11:39, 23 June 2022 (UTC)
 * There's about 40,000 active editors on English Wikipedia, but we can't organize ourselves, so I guess that's too many. Card Zero  (talk) 12:33, 23 June 2022 (UTC)


 * For a first approach of the subject, I recommend checking out the work of fr:Mehdi Moussaïd if you can understand French (there’s a few articles in English on his website but much is untranslated). He is best-known for the Youtube vulgarization channel "Fouloscopie" (foule = crowd, so a rough translation of the channel name is "Crowdscience"), but he is a serious researcher at the Max Planck Institute, so he does give bibligraphies and such. Now that he’s Youtube-famous, he can leverage his community to run experiments with lots of people without paying them - quite a smart move if you ask me. Tigraan Click here for my talk page ("private" contact) 13:44, 23 June 2022 (UTC)
 * And speaking of Dunbar's number, it is probably not a coincidence that a company is usually not more than 100-150 men! 2601:646:8A81:6070:640D:F1C9:3B1D:1044 (talk) 02:28, 24 June 2022 (UTC)

Star color
What causes the change in color as stars get hotter from red to yellow to white to blue? Despite many online sites stating the fact that as temperature increases the color changes I cannot find what makes temperature change the color of the star. 172.112.210.32 (talk) 20:56, 22 June 2022 (UTC)


 * It's pretty much straight blackbody radiation. It's not just stars, but any matter that tends to follow the same changes in color with temperature. TenOfAllTrades(talk) 21:39, 22 June 2022 (UTC)


 * And just to make the point explicit, the temperature that matters is the temperature of the star's visible surface, not the layers hidden below it, which generally are much hotter. --174.95.83.56 (talk) 04:02, 23 June 2022 (UTC)


 * Apparent temperature may be affected by relativistic Doppler effect; (i.e.: redshift / blueshift)* --2603:6081:1C00:1187:5D0E:1FD1:561A:AB20 (talk) 07:36, 23 June 2022 (UTC)
 * *not to be confused with redfish / bluefish
 * See also Planckian locus (not to be confused with the Black locust). --Lambiam 11:19, 23 June 2022 (UTC)
 * Also see Wien's displacement law. It's just blackbody radiation. As the temperature of the gas gets higher, so does the temperature of the radiation it emits. The relevant temperature is the temperature of the photosphere, which is the layer from where radiation can escape to space as the mean free pathlength of the light gets longer than the scaleheight of the atmosphere. The apparent temperature can be affected by Doppler shift, but this effect is so small that under normal circumstances you cannot see the effect on the broad-band colour. You can see the effect of movement on the spectral lines and in case of white dwarfs the gravitational redshift may be visible in spectral lines too. PiusImpavidus (talk) 11:41, 23 June 2022 (UTC)