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JoshuaZ comments on Astronomy, space exploration and the Great Filter - Less Wrong Discussion

23 Post author: JoshuaZ 19 April 2015 07:26PM

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Comment author: JoshuaZ 08 May 2015 11:38:35PM 0 points [-]

This hypothesis is interesting and not one I've seen at all before. It seems to run partially afoul of the same problem that many small early filters would run into- one would be more likely to find civilizations around red dwarfs. Is there a way around that?

Comment author: OrphanWilde 11 May 2015 01:33:20PM 1 point [-]

The low luminosity of red dwarf stars makes them unsuitable for an earth-like environment, I believe. I don't have enough information to comment on a non-earthlike environment supporting life.

The stability of red dwarves, however, could work as a filter in itself, limiting the number of global extinction events.

Comment author: JoshuaZ 11 May 2015 03:08:36PM 0 points [-]

The low luminosity of red dwarf stars makes them unsuitable for an earth-like environment, I believe. I don't have enough information to comment on a non-earthlike environment supporting life.

Red dwarfs have a smaller habitable zone than our sun, but if you have a planet close enough to a red dwarf this isn't an issue. This is exactly the problem: if there are some set of not so likely series of events that will occur, then one expects to find civilizations around red dwarfs. If one expects that's not the case then the big habitable zones on somewhat bigger stars make one more likely to expect a civilization around those stars. We see the second.

The stability of red dwarves, however, could work as a filter in itself, limiting the number of global extinction events.

Possibly, but I don't think that any of the major extinction events in Earth history are generally attributed to large solar flares or coronal mass ejections or the like. So it seems like asteroids and geological considerations are more than enough to provide extinction events.

Comment author: OrphanWilde 11 May 2015 03:20:03PM 3 points [-]

Red dwarfs have a smaller habitable zone than our sun, but if you have a planet close enough to a red dwarf this isn't an issue. This is exactly the problem: if there are some set of not so likely series of events that will occur, then one expects to find civilizations around red dwarfs. If one expects that's not the case then the big habitable zones on somewhat bigger stars make one more likely to expect a civilization around those stars. We see the second.

  • AFAIK planets close enough to a Red Dwarf to get enough lumosity stop being earth-like due to other effects (likely rotational periods, tidal forces).
Comment author: JoshuaZ 11 May 2015 06:27:08PM 0 points [-]

The situation is a bit more complicated. Wikipedia has a good summary. There's also been more recent work which suggests that the outer end of the habitable zone around red dwarfs may be larger than than earlier estimates. See my earlier comments here on this subject.