A-1 - Encouraged by What You Read?

Two weeks ago, I introduced my blog by describing my issue with how each of the Star Warsmovies references civilizations in “a galaxy far, far away.” 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’s spiral arms (where most new stars are formed) must be neither too tight nor too loose to harbor life.

Spiral Arms Must Be Just-Right
To 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.


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

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’s spiral arms. Also, they possess more spurs and “feathers” (bridges) between the spiral arms than does the MWG and/or a central bulge different in size and shape than the MWG’s. As I explain in my book, The Creator and the Cosmos,1 and in the fine-tuning compendium on our website,each of these three structural differences with the MWG makes the other galaxies noncandidates for the possibility of hosting advanced life.


Figure 2: Spiral Galaxies That Most Closely Match the Structure of the MWG. 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 credits: 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

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.

When a galaxy’s 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.

When a galaxy’s 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.

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.

MWG’s Spiral Arms Are Just-Right
A study by astronomers Si-Yue Yu and Luis Ho shows that only certain kinds of spiral galaxieswill possess spiral arms that are not too tightly or too loosely wound.3 Yu and Ho analyzed 79 spiral galaxies where high-resolution images of the galaxies’ spiral structure were available. They found that:

  • the larger a galaxy’s central bulge, the more tightly wound are its spiral arms;
  • the higher the stellar concentration, the more tightly wound are the spiral arms; and
  • the larger the total galaxy stellar mass, the more tightly wound are the spiral arms.

For galaxies where the central stellar velocity dispersion was greater than 100 kilometers per second, the two astronomers noted that the lower the central stellar velocity dispersion, the more tightly wound are the spiral arms.

All these correlations that the pair discovered are consistent with the predictions of the density wave theory for the origin and maintenance of spiral arms. This additional evidence for density wave theory means that, contrary to the assertions of young-earth creationists,4astronomers really do possess a good and observationally verified understanding of galaxy spiral arm structure in the context of an approximately 14-billion-year-old universe.5

Though not addressed by Yu and Ho, the correlations they found provide additional evidence for the fine-tuning of the MWG for the benefit of advanced life. Relative to other large spiral galaxies, the MWG’s mass consists of few stars. This low ratio of stellar mass to total mass is exactly what is required for the MWG to have its spiral arms wound up to the degree required for the existence of advanced life on a planet located halfway between two of its spiral arms at the just-right distance from the center of the galaxy (see figure 3).


Figure 3: Location of the Solar System in the Milky Way Galaxy. The yellow dot shows the solar system’s location halfway between two of the MWG’s smaller arms. Image credit: NASA/JPL-Caltech/R. Hurt

The degree of fine-tuning required for a spiral galaxy’s arms to be ideally wound adds to the more than one hundred characteristics of a galaxy6 that must be fine-tuned for advanced life to be possible. Such extensive fine-tuning shouts to all of us that there must exist a super-intelligent, super-powerful Being who was intent on creating a home where human beings could live, thrive, and discover him.

Check out more from Reasons to Believe @Reasons.org

  1. Hugh Ross, The Creator and the Cosmos: How the Latest Scientific Discoveries Reveal God, 4th ed. (Covina, CA: RTB Press, 2017), 200–206, 233–266.
  2. Hugh Ross, “RTB Design Compendium (2009),” Today’s New Reason to Believe (blog), Reasons to Believe(November 16, 2010), https://www.reasons.org/explore/blogs/todays-new-reason-to-believe/read/tnrtb/2010/11/16/rtb-design-compendium-2009.
  3. Si-Yue Yu and Luis C. Ho, “On the Connection between Spiral Arm Pitch Angle and Galaxy Properties,” Astrophysical Journal 871, no. 2 (February 1, 2019): id. 194, doi:10.3847/1538-4357/aaf895.
  4. Jonathan Sarfati, Refuting Compromise, 2nd ed. (Atlanta: Creation Book Publishers, 2011), 180; Andy McIntosh and Carl Wieland, “‘Early’ Galaxies Don’t Fit,” Creation 25 (March 2003): 28–30; D. Russell Humphreys, “Evidence for a Young World,” Impact #384 (Santee, CA: Institute for Creation Research, June 2005): i–ii, https://www.icr.org/article/evidence-for-young-world/; Harold S. Slusher, Age of the Universe (El Cajon, CA: Institute for Creation Research, 1980), 15–16; Danny R. Faulkner, “Galaxies—Unexplained Spirals,” Answers (Petersburg, KY: Answers in Genesis, January–March, 2011): 54–56, https://answersingenesis.org/astronomy/cosmology/galaxies-unexplained-spirals/; Jason Lisle, The Age of the Universe, Part 2 (March 20, 2008), https://answersingenesis.org/astronomy/the-age-of-the-universe-part-2/
  5. Hugh Ross, A Matter of Days: Resolving a Creation Controversy, 2nd expanded ed. (Covina, CA: RTB Press, 2015), 206–208.
  6. Ross, “RTB Design Compendium (2009).”


About The Author

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. I also am eager to equip Christians to engage, rather than withdraw from or attack, educated non-Christians. One of the approaches I’ve developed, with the help of my RTB colleagues, is a biblical creation model that is testable, falsifiable, and predictive. I enjoy constructively integrating all 66 books of the Bible with all the science disciplines as a way to discover and apply deeper truths. 1 Peter 3:15–16 sets my ministry goal, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience." Hugh Ross launched his career at age seven when he went to the library to find out why stars are hot. Physics and astronomy captured his curiosity and never let go. At age seventeen he became the youngest person ever to serve as director of observations for Vancouver's Royal Astronomical Society. With the help of a provincial scholarship and a National Research Council (NRC) of Canada fellowship, he completed his undergraduate degree in physics (University of British Columbia) and graduate degrees in astronomy (University of Toronto). The NRC also sent him to the United States for postdoctoral studies. At Caltech he researched quasi-stellar objects, or "quasars," some of the most distant and ancient objects in the universe. Not all of Hugh's discoveries involved astrophysics. Prompted by curiosity, he studied the world’s religions and "holy books" and found only one book that proved scientifically and historically accurate: the Bible. Hugh started at religious "ground zero" and through scientific and historical reality-testing became convinced that the Bible is truly the Word of God! When he went on to describe for others his journey to faith in Jesus Christ, he was surprised to discover how many people believed or disbelieved without checking the evidence. Hugh's unshakable confidence that God's revelations in Scripture and nature do not, will not, and cannot contradict became his unique message. Wholeheartedly encouraged by family and friends, communicating that message as broadly and clearly as possible became his mission. Thus, in 1986, he founded science-faith think tank Reasons to Believe (RTB). He and his colleagues at RTB keep tabs on the frontiers of research to share with scientists and nonscientists alike the thrilling news of what's being discovered and how it connects with biblical theology. In this realm, he has written many books, including: The Fingerprint of God, The Creator and the Cosmos, Beyond the Cosmos, A Matter of Days, Creation as Science, Why the Universe Is the Way It Is, and More Than a Theory. Between writing books and articles, recording podcasts, and taking interviews, Hugh travels the world challenging students and faculty, churches and professional groups, to consider what they believe and why. He presents a persuasive case for Christianity without applying pressure. Because he treats people's questions and comments with respect, he is in great demand as a speaker and as a talk-radio and television guest. Having grown up amid the splendor of Canada's mountains, wildlife, and waterways, Hugh loves the outdoors. Hiking, trail running, and photography are among his favorite recreational pursuits - in addition to stargazing. Hugh lives in Southern California with his wife, Kathy, and two sons.

Email Sign-up

Sign up for the TWR360 Newsletter

Access updates, news, biblical teaching and inspirational messages from powerful Christian voices.

Thank you for signing up to receive updates from TWR360.

Required information missing