posted by RRRGroup at
Saturday, February 08, 2014
Rich,Turning it around, why wouldnt they spot us, assuming they exist?An youve used the perfect little picture of Earth to illustrate your point, but its mere visual perception.
By Al12, at Saturday, February 08, 2014
AI12...We (the Earth) are truly insignificant, in the context of the Milky Way, let alone the whole Universe....that's my attempted point.RR
By RRRGroup, at Saturday, February 08, 2014
But doesn't that go for all the other planets too?
By Red Eye View, at Saturday, February 08, 2014
RichI suppose we all have a place in this universe or this milky way or we wouldnt existTo say we are insignificant is in my opinion extremely naive considering the lack of supposed knowledge we have or do not have of this universe or our place in it.
AI12...You know I admire your thinking.But, in the objective scheme of things, we and the Earth matter not.It's like that grain of sand on the beach.RR
@AI12The term Rich was looking for is the "Mediocrity Principle" see http://en.wikipedia.org/wiki/Mediocrity_principle which holds we inhabit an "unexceptional planet" which orbits an "unexceptional star" that orbits at an "unexceptional" distance an "unexceptional galaxy" that has 100 billion stars. It is the principle that is at the heart of SETI-- the thinking being that since our home planet is unexceptional then ETI will be unexceptional too. A recent paper by astronomers at the Keck Observatory estimated that 1 in five star in our galaxy has planets in the "Habitable Zone"see: http://www.keckobservatory.org/recent/entry/one_in_five_stars_has_earth_sized_planet_in_habitable_zoneOur star, Sol [for the lack of a better name] is only visible to stars within 56.67 light years. There are about 10,588 stars within that distance to earth but according to the "Habitable Star short list" created by astronomers Jill Tarter and Margaret Turnbull there are only 32 Sol-like stars within that distance. see http://www.nasa.gov/vision/universe/newworlds/HabStars.htmlonly a few have been found to have planets and no signals were heard when examined by radio-telescopes.On the other hand, out of the 1075 planets in 813 planetary systems including 178 multiple planetary systems as of 1 February 2014 [see Wikipedia - exoplanet] not one has shown any indication of intelligent life. Earth seems to be a "Goldilocks Planet" Of the list of exoplanets only a small hand full appear to be "earth-like" see: http://www.space.com/19201-most-earth-like-alien-planet.htmlSo consider the numbers: 5 planets that are possibly 'earth-like" [see: http://en.wikipedia.org/wiki/Earth_Similarity_Index ]out of 1075 that is only 0.4%... and so far Earth is still the only "known" planet with life. While the "Drake Equation" lists the possible variables involved in determining the probability of finding ETI... we have no reasonable way to actually fill in those variables with reliable numbers which makes the "certainty" of ETI lower than one might expect.One other thing to consider: if we ever do hear ETI singing to our radio telescopes-- the farther they are away the more advanced they likely are. Why? We can infer this from the travel time of the signal. If we were to hear ET and he his signal originates 56 light years a away then ET is at least 56 years more advanced than humanity. regards,jhc
By JHC, at Monday, February 10, 2014
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