The vastness of this universe
The vastness of this universe and the uniqueness of the Earth point us to ask questions about why we exist in this particular space and time. What is the purpose of our life on this Earth? Is there a Creator behind this amazing universe and our world? How can we know and communicate with the Creator? So many of these questions have been asked over the ages in human civilization.
A review of the size of the Milky Way gives people some idea the vastness of the galaxy we live in. The latest scientific measurement of the Milky Way’s diameter is about 100,000 light years. This vague number usually provides little understanding of the vastness of its size, even though we know the distance of one light year is the distance for light to travel in one year.
That’s why researchers like to use different scales to compare the size of the solar system. The below examples are used by the Center for Astrophysics (CFA) at Harvard University to help people make a mental model in their mind about the size of the Milky Way and the universe:
- Reducing the scale of our entire solar system to the size of a quarter gives us perspective about the size of Milky Way with respect to our solar system. On this scale, the overall size of our Milky Way galaxy would be close to the size of the United States!
- Since the sun is at the center but smaller than the solar system, the sun appears like a small piece of dust based on the model scale of Milky Way to the United States. If we shrink the Milky Way galaxy to the scale of 1 m2, the entire solar system is smaller than the nucleus of a human cell. The Earth is even much smaller in this scale, let alone the size of humans with respect to our galaxy.
- Another helpful mental model shows the comparative size of the universe we can see. Our entire Milky Way galaxy is further reduced to the scale size of a CD. The adjacent galaxy that is closest to Milky Way is the spiral galaxy, name “Andromeda.” On this scale, Andromeda will appear to be about eight feet away. Due to the time it takes light to travel in space, the farthest galaxies we have ever seen once its light reaches us, as seen in the Hubble Deep Field, would be about nine miles away. When the light from the edge of the observable universe reaches us, it shows us the beginning of the universe during the start of the Big Bang. Therefore, it gives us some idea about the age of the universe. The furthest we can possibly see of the entire universe is about ten miles from us on the scale of Milky Way to a regular CD. This corresponds to about fourteen billion light years away from our planet Earth.
I will discuss more about the vastness of this universe point to the Mighty power of the Creator in my next blog!
https://www.cfa.harvard.edu/seuforum/howfar/across.html, accessed on June 22, 2019
 https://www.cfa.harvard.edu/seuforum/howfar/howfar.html, or https://www.cfa.harvard.edu/seuforum/howfar/HowBigUniverse.pdf
 Reference to ratio of solar system diameter to earth diameter: Richard Feynman, The Feynman Lectures on Physics, Vol.1, Chaps.1, 2, and 3.
 Estimated as of 2015 around 13.799±0.021 billion years for the age of the universe, Planck Collaboration (2016). “Planck 2015 results. XIII. Cosmological parameters (See Table 4 on page 32 of pdf).” Astronomy and Astrophysics. 594: A13.
Note: Excerpt from my book A PHYSICIST’S PERSPECTIVE ON GOD
THE VASTNESS OF THE UNIVERSE
The Vastness of This Universe?
I have written many articles on science and faith here on Science and Life Blogs