Friday, July 11, 2014

2-D Galaxies in a 3-D Universe



Armchair Science is a Kindle ebook available at Amazon. It contains over 120 short mysteries of science that can be solved from a single observational clue, without the need for experimentation.




Science is not a collection of facts. Science is what facts teach us; what we can learn about our universe, and ourselves, by deductive thinking. From observations of the night sky, made without the aid of telescopes, we can deduce that the universe is expanding, that the universe is not infinitely old, and why black holes exist. Without resorting to experimentation or mathematical analysis, we can deduce that gravity is a curvature in space-time, that the particles that compose light have no mass, that there is a theoretical limit to the number of different elements in the universe, and that the earth is billions of years old. Likewise, simple observations on animals tell us much about the migration of continents, the evolutionary relationships among classes of animals, why the nuclei of cells contain our genetic material, why certain animals are long-lived, why the gestation period of humans is 9 months, and why some diseases are rare and other diseases are common. In “Armchair Science”, the reader is confronted with 129 scientific mysteries, in cosmology, particle physics, chemistry, biology, and medicine. Beginning with simple observations, step-by-step analyses guide the reader toward solutions that are sometimes startling, and always entertaining. “Armchair Science” is written for general readers who are curious about science, and who want to sharpen their deductive skills.

Here is an excerpt from the book:

Clue 36. The universe is three dimensional, but most collections of large objects in the universe, such as galaxies, are flat, seemingly two-dimensional.



Illustration. Collage of galaxies, all somewhat flat. Source: NASA.

Deduction. Galaxies must be spinning.

Resolution. Gravity causes objects to come together, in a ball. With all the gravity produced by mass objects, one would expect the universe to be composed of spherical things. Indeed, stars and planets are round, but most collections of large things in the universe are flat. These would include virtually every galaxy, the planar orbits of the planets, and accretion disks.

The reason is simple: gravity pulls things into a ball, while angular momentum tends to stretch everything out into a disk. Objects that spin, even solid balls, have a tendency to be disk-shaped. Spinning objects that seem to be spherical are more accurately described as oblate spheroids. For example, the earth bulges at the equator, where the centrifugal force is greatest.

When we look into the skies, and we see flat galaxies, it is a safe bet that they are spinning.

I urge you to read more about this book. There's a good "look inside" of the book at the Amazon store.

- Jules J. Berman, Ph.D., M.D.

tags: deductive science, science mysteries, deductive reasoning, ebook, general science reading, general science book, science puzzles, scientific amusements