Wikipedia:Reference desk/Archives/Science/2016 November 24

= November 24 =

Sources (RR Lyrae variables)
The GEOS maxima database of RR Lyrae stars which appears to be a solid source lists (if I counted correctly) 123 RR Lyrae variables in Coma Berenices, while SEDS Messier Database here says there are only 47 known such variables. Which one to choose? Could it be outdated? Brandmeistertalk  12:13, 24 November 2016 (UTC)
 * Those 47 RR Lyrae are within the globular cluster M53 and are much harder to observe than the field stars from GEOS. If your intention is to observe RR Lyrae stars with an amateur-class telescope, then use the GEOS database. --Wrongfilter (talk) 12:52, 24 November 2016 (UTC)
 * Meh, so I read it the wrong way. Thanks.Brandmeistertalk  15:03, 24 November 2016 (UTC)

Space colonies in intergalactic space
How could one build a space habitat in intergalactic space. Wikipedia talks about how they can be built,but only ones close to earth?Uncle dan is home (talk) 18:46, 24 November 2016 (UTC)
 * The same way you would anywhere else. There's nothing different about it. Space is empty. The only real issue is that the habitat needs to be self-sufficient since it's a long way down the road to the nearest planet. And it couldn't use solar power since it's nowhere near a star, so the habitat would need a different power source, likely nuclear fission. The real question is why you'd want to build a habitat there. I guess if you really want solitude, it's the ultimate way to "get away from it all". --47.138.163.230 (talk) 20:35, 24 November 2016 (UTC)
 * Not necessarily: there are stars in intergalactic space. HenryFlower 20:48, 24 November 2016 (UTC)
 * How odd... we have an article rogue star (well, "intergalactic star" is the formal title, but that is so much less poetic). But the link above doesn't lead to it.  Well, didn't anyway. :) Wnt (talk) 21:40, 24 November 2016 (UTC)

What about artificial sunlight?Uncle dan is home (talk) 22:19, 24 November 2016 (UTC)
 * From what and where? Whoop whoop pull up Bitching Betty &#124; Averted crashes 00:00, 25 November 2016 (UTC)


 * Another big problem would be the lack of material from which to construct a space station. You could build one in a galaxy where there is matter, then shoot it off into intergalactic space, but it would take tens of thousands of years even at the speed of light.  So, doing so seems like a huge waste of time and energy just to "get away from it all".  StuRat (talk) 04:44, 25 November 2016 (UTC)


 * Well in another million years or so maybe we'll be able to arrange for a star plus some planets to leave this galaxy for another one using the slingshot effect like we do for satellites now. I can't see the point of having a habitat in interstellar space, just sending stuff that is frozen or a robot with plans to reconstruct stuff or even people in another galaxy sounds best to me. Dmcq (talk) 11:09, 25 November 2016 (UTC)


 * It is all fruitless talk and baseless fantasy. Building space colony outside earth, even on the surface of Mars requires many orders of magnitude more energy, material and effort than we will ever be able to muster. --AboutFace 22 (talk) 18:31, 25 November 2016 (UTC)
 * Prove it. ←Baseball Bugs What's up, Doc? carrots→ 22:05, 25 November 2016 (UTC)
 * I think most of the folks building colonies in intergalactic space start with a) an experimental warp drive, and b) an "Uh-oh..." Wnt (talk) 22:41, 25 November 2016 (UTC)
 * That is simply false. The material and energy required is already at mars, it just requires some robots to convert them like we did with minerals and rocks and suchlike on earth. That's a hard enough task but it certainly achievable and mainly with the application of lots of intelligence rather than natural resources. Dmcq (talk) 00:02, 26 November 2016 (UTC)
 * Terraforming Mars has been discussed for quite some time. Carl Sagan talked about ways to terraform both Venus and Mars, and Mars seemed like the better bet. Both would require significant work, but nothing like impossible. Resources are not the problem. The problem is commitment, or lack of if. ←Baseball Bugs What's up, Doc? carrots→ 00:32, 26 November 2016 (UTC)
 * Yes, see for instance: generation ship, interstellar ark, sleeper ship, embryo space colonization, which I failed to link previously. --47.138.163.230 (talk) 10:25, 26 November 2016 (UTC)


 * To live anywhere, you need material, energy, and the technology to manipulate them. With sufficiently advanced technology, you can convert mass to energy, so it comes down to mass. There is mass in interstellar space in many forms: rogue stars as mentioned above, for sure. There is certianly also hydrogen, and it is almost certain that there is solid matter in the form of dust. It is highly likely that there are solid bodies from the size of brown dwarf stars all the way down to the size of pebbles, also. By the time you have invented the technology to reach intergalactic space (see Kardashev scale), you will almost also have the technology to us this mass to create whatever habitat you desire, from a single home to a Dyson sphere. -Arch dude (talk) 03:33, 26 November 2016 (UTC)


 * The problem with this mass is most of it is extremely sparse, so it would take vast amounts of energy and time to collect it, and you may very well use more energy getting to each particle than the energy you would get from converting 100% of that mass into energy. So, better to grab some mass where most of it is located, in dense pockets, like in galaxies, and move it to where you want it. StuRat (talk) 03:42, 26 November 2016 (UTC)


 * Getting to interglactic space requires a minimum of thousands of years, and it requires unimaginably advanced technology. Thus, an intergalactic settler should not be bothered by the time or technology taken to gather materials. For a modest little settlement, a single brown dwarf or equivalent should be more than adequate. For a biggish Dyson sphere, you might want to take an extra millennium or so to gather more material if you cannot find a convenient binary star to start from. -Arch dude (talk) 03:25, 27 November 2016 (UTC)


 * It may take millions of years to collect enough dust particles to make something useful there. And there's still the issue of it potentially taking more energy to collect them than you get from them.  So yes, you would need to find something large there to mine. StuRat (talk) 18:31, 27 November 2016 (UTC)