{"id":12207,"date":"2019-06-03T09:00:00","date_gmt":"2019-06-03T09:00:00","guid":{"rendered":"http:\/\/reasons.org\/spiral-arms-designed-for-life\/"},"modified":"2019-06-03T09:00:00","modified_gmt":"2019-06-03T09:00:00","slug":"spiral-arms-designed-for-life","status":"publish","type":"post","link":"https:\/\/reasons.org\/creation\/life\/spiral-arms-designed-for-life","title":{"rendered":"Spiral Arms Designed for Life"},"content":{"rendered":"
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Two weeks ago, I introduced my blog<\/a> by describing my issue with how each of the Star Wars<\/em> movies references civilizations in \u201ca galaxy far, far away.\u201d We astronomers have observed thousands of far, far away galaxies and so far none possess features similar enough to our Milky Way Galaxy (MWG) to be possible candidates to host an advanced civilization. In this post I describe yet another feature, namely that a galaxy\u2019s spiral arms (where most new stars are formed) must be neither too tight nor too loose to harbor life. <\/span><\/p>\n

Spiral Arms Must Be Just-Right<\/strong>
\nTo demonstrate some of these features, figure 1 shows a detailed map of the MWG that was constructed from observations of different parts of the galaxy where each was observed at electromagnetic wavelengths spanning from the radio end of the spectrum to the X-ray end.<\/p>\n

\"blog__inline-spiral-arms-designed-for-life-1\"<\/p>\n

Figure 1: Structure of the Milky Way Galaxy. <\/em><\/strong>This map of the MWG was constructed from observations across the electromagnetic spectrum of different portions of the galaxy. Image <\/em>credit: NASA\/JPL-Caltech\/R. Hurt<\/em><\/p>\n

Figure 2 shows images of ten spiral galaxies that come the closest to matching the central bulge and spiral structure of the MWG. In every case, the spiral arms of these ten galaxies fail to manifest the symmetry of the MWG\u2019s spiral arms. Also, they possess more spurs and \u201cfeathers\u201d (bridges) between the spiral arms than does the MWG and\/or a central bulge different in size and shape than the MWG\u2019s. As I explain in my book, The Creator and the Cosmos<\/em><\/a>,1<\/sup> and in the fine-tuning compendium<\/a> on our website,2 <\/sup>each of these three structural differences with the MWG makes the other galaxies noncandidates for the possibility of hosting advanced life.<\/p>\n

\"blog__inline-spiral-arms-designed-for-life-2\"<\/p>\n

Figure 2: Spiral Galaxies That Most Closely Match the Structure of the MWG. <\/em><\/strong>Top left to right: Andromeda Galaxy, NGC 4526, M100, Pinwheel Galaxy; middle left to right: NGC 908, M83, NGC 4921, NGC 1232; bottom left to right: NGC 6384, NGC 3344. Image c<\/em>redits: Adam Evans, NASA\/ESA\/Hubble Space Telescope\/High-Z Supernova Search Team, Schulman Foundation, ESA\/NASA, ESO, ESO, NASA\/ESA\/Hubble Heritage Archive, ESO, NASA\/ESA\/Hubble, NASA\/ESA\/Hubble <\/em><\/p>\n

Now, astronomers have found another feature of spiral galaxies that must be fine-tuned for advanced life to be possible. They have discovered that spiral galaxies are a little like human beings in that it is not good for them to be too tightly or too loosely wound up<\/span>.<\/p>\n

When a galaxy\u2019s spiral arms are tightly wound, the arms will be too close together for a planet in between any two of the spiral arms to safely host advanced life. Such a planet will be too close to the powerful ultraviolet radiation emitted by the young giant stars that reside in the spiral arms and too close to gravitational disturbances from giant molecular clouds that also reside in the spiral arms. Furthermore, when the spiral arms are tightly wound, they generate an inordinate number of spurs and feathers between the arms. These spurs and feathers expose planets in between the spiral arms to additional deadly radiation and gravitational disturbances.<\/p>\n

When a galaxy\u2019s spiral arms are loosely wound, the symmetry of their structure is easily disturbed. Such structure is prone to disruption by nearby galaxies, even nearby dwarf galaxies, and by internal inhomogeneities inside the galaxy.<\/p>\n

What about galaxies with no spiral arms? Such galaxies are noncandidates for advanced life since the density of stars in galaxies without spiral arms is far greater than in galaxies with spiral arms. The star density is so great that planets with features that make the existence of life possible will experience disturbed orbits and high bombardment frequency by comets, asteroids, molecular clouds, and planetesimals.<\/p>\n

MWG\u2019s Spiral Arms Are Just-Right<\/strong>
\nA study by astronomers Si-Yue Yu and Luis Ho shows that only certain kinds of spiral galaxies<\/a> will possess spiral arms that are not too tightly or too loosely wound.3<\/sup> Yu and Ho analyzed 79 spiral galaxies where high-resolution images of the galaxies\u2019 spiral structure were available. They found that:<\/p>\n