Fine-Tuning and Dimensionless Physical Constants

Fine-Tuning and Dimensionless Physical Constants November 15, 2019


Galapagos tube worms!
A 2011 public domain photo, from the National Oceanographic and Atmospheric Administration, of a colony of Riftia pachyptila tube worms observed, with anemones and mussels colonizing in close proximity, near a deep ocean geothermal vent in the Galapagos Rift.


I have some bad news and some good news.  First, the bad:


“California landfills are belching high levels of climate-warming methane: Airborne remote sensing spots the Golden State’s biggest emitters of the gas from the sky”


“New CDC Report on Superbugs Is Full of Bad News”


But here’s some (potentially) good news:


“How to Cut U.S. Carbon Pollution by Nearly 40 Percent in 10 Years: A bill in Congress could slash American greenhouse-gas emissions. It’s even bipartisan—if you squint.”


At least at first glance, I find the idea intriguing.




For a long-term project that I have in mind, I’m trying to formulate discussions of certain scientific concepts.  I want eventually to publish what I’m working on, but a major initial goal is simply to be certain that I myself understand what I’m talking about.  I make no claim to either originality or finality at this point, and I would be happy if anybody with substance expertise decides to chime in — charitably and gently, I hope! — with suggestions or corrections:


The proposition that the universe is fine-tuned for life asserts that the conditions that allow life to exist can occur only when certain universal dimensionless physical constants lie within a very narrow range of values.  In other words, if any one of several fundamental constants were only slightly different, the universe would likely be inhospitable to the establishment and development of matter, of astronomical structures, of diversity in chemical elements, and (therefore) of biological life in any sense that we currently know or understand or can really envision.


What is a physical constant?  It is a physical quantity — sometimes called a universal constant or a fundamental physical constant — that is generally believed to both universal in its nature and to have a constant value over time.  (A mathematical constant, by contrast, also has a fixed numerical value but doesn’t directly involve any actual physical measurement.)


Current science is aware of a number of physical constants.  Of these, probably the most famous is c, the speed of light in a vacuum.  (It appears, for example, in the famous Einsteinean equation E = mc2.)   Its exact value is 299792458 meters per second (or approximately 300000 km/s (186000 mi/s).  In 1905, Einstein’s special theory of relativity postulated that the speed of light c with respect to any inertial frame is a constant and that it is independent of the motion of the light source.


Others physical constants include the gravitational constant G, the Planck constant h, the electric constant ε0, and the elementary charge e


What does it mean to speak of dimensionless physical constants?  Dimensionlessness (to coin a word, perhaps) means that the physical constant is a pure number having no units attached and having a numerical value that is independent of whatever system of units or measurement may be used. Perhaps the best-known example of a dimensionless physical constant is the fine-structure constant, α, which has an approximate value of ​1137.036.


To be continued.



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