From Limits for the Universe by Hugh Ross, Ph.D.
1. Gravitational coupling constant. If larger: No stars less than 1.4 solar masses, hence short stellar lifespans. If smaller: No stars more than 0.8 solar masses, hence no heavy element production 2. Strong nuclear force coupling constant. If larger: No Hydrogen; nuclei essential for life are unstable. If smaller: No elements other than Hydrogen.
3. Weak nuclear force coupling constant. If larger: All Hydrogen is converted to helium in the Big Bang, hence too much heavy elements. If smaller: No Helium produced from Big Bang, hence not enough heavy elements.
4. Electromagnetic coupling constant. If larger: No chemical bonding; elements more massive than Bboron are unstable to fission. If smaller: No chemical bonding.
5. Ratio of protons to electrons formation If larger: electromagnetism dominates gravity preventing galaxy, star, and planet formation. If smaller: Electromagnetism dominates gravity preventing galaxy, star, and planet formation.
6. Ratio of electron to proton mass. If larger: No chemical bonding. If smaller: No chemical bonding.
7. Expansion rate of the universe. If larger: No galaxy formation. If smaller: Universe collapses prior to star formation.
8. Entropy level of universe. If larger: No star condensation within the proto-galaxies If smaller: No proto-galaxy formation
9. Mass density of the universe. If larger: Too much Deuterium from Big Bang, hence stars burn too rapidly If smaller: No Helium from Big Bang, hence not enough heavy elements
10. Age of the universe. If older: No solar-type stars in a stable burning phase in the right part of the galaxy. If younger: Solar-type stars in a stable burning phase would not yet have formed.
11. Initial uniformity of radiation. If smoother: Stars, star clusters, and galaxies would not have formed. If coarser: Universe by now would be mostly Black Holes and empty space.
12. Average distance between stars. If larger: Heavy element density too thin for rocky planet production, If smaller: Planetary orbits become destabilized.
13. Solar luminosity. If increases too soon: Runaway Greenhouse effect. If increases too late: Frozen oceans.
14. Fine structure constant*. If larger: No stars more than 0.7 solar masses. If smaller: No stars less then 1.8 solar masses.
15. Decay rate of the proton. If greater: Life would be exterminated by the release of radiation. If smaller: Insufficient matter in the Universe for life.
16. C12 to O16 energy level ratio. If larger: Insufficient Oxygen If smaller: Insufficient Carbon.
17. Decay rate of Be8. If slower: Heavy element fusion would generate catastrophic explosions in all the stars. If faster: No element production beyond Beryllium and, hence, no life chemistry possible.
18. Mass difference between the neutron and the proton. If greater: Protons would decay before stable nuclei could form If smaller: Protons would decay before stable nuclei could form.
19. Initial excess of nucleons over anti-nucleons. If greater: Too much radiation for planets to form. If smaller: Not enough matter for galaxies or stars to form.
20. Galaxy type. If too elliptical: Star formation ceases before sufficient heavy element buildup for life chemistry. If too irregular: Radiation exposure on occasion is too severe and/or heavy elements for life chemistry are not available.
21. Parent star distance from center of galaxy. If farther: Quantity of heavy elements would be insufficient to make rocky planets If closer: Stellar density and radiation would be too great.
22. Number of stars in the planetary system. If more than one: Tidal interactions would disrupt planetary orbits. If less than one: Heat produced would be insufficient for life.
23. Parent star birth date. If more recent: Star wuld not yet have reached stable burning phase. If less recent: Stellar system would not yet contain enough heavy elements.
24. Parent star mass. If greater: Luminosity would change too fast; star would burn too rapidly. If less: Range of distances appropriate for life would be too narrow; tidal forces would disrupt the rotational period for a planet of the right distance; UV radiation would be inadequate for plants to make sugars and Oxygen.
25. Parent star age. If older: Luminosity of star would change too quickly. If younger: Luminosity of star would change too quickly.
26. Parent star color. If redder: Photosynthetic response would be insufficient. If bluer: Photosynthetic response would be insufficient.
27. Supernovae eruptions. If too close: Life on the planet would be exterminated. If too far: Not enough heavy element ashes for the formation of rocky planets. If too infrequent: Not enough heavy element ashes for the formation of rocky planets. If too frequent: Life on the planet would be exterminated.
28. White/Dwarf binaries. If too few: Insufficient fluorine produced for life chemistry to proceed. If too many: Disruption of planetary orbits from stellar density; life on the planet would be exterminated.
29. Surface gravity (escape velocity). If stronger: Atmosphere would retain too much ammonia and methane. If weaker: Planet's atmosphere would lose too much water.
30. Distance from parent star. If farther: Planet would be too cool for a stable water cycle. If closer: Planet would be too warm for a stable water cycle.
31. Inclination of orbit. If too great: Temperature differences on the planet would be too extreme.
32. Orbital eccentricity. If too great: Seasonal temperature differences would be too extreme.
33. Axial tilt. If greater: Surface temperature differences would be too great. If less: Surface temperature differences would be too great.
34. Rotation period. If longer: Diurnal temperature differences would be too great. If shorter: Atmospheric wind velocities would be too great.
35. Gravitational interaction with a moon. If greater: Tidal effects on the oceans, atmosphere, and rotational period would be too severe. If less: Orbital obliquity changes would cause climatic instabilities.
36. Magnetic field. If stronger: Electromagnetic storms would be too severe. If weaker: Inadequate protection from hard steller radiation.
37. Thickness of crust. If thicker: Too much Oxygen would be transferred from the atmosphere to the crust. If thinner: Volcanic and tectonic activity would be too great.
38. Albedo (ratio of reflected light to total amount falling on surface). If greater: Runaway ice age would develop. If less: Runaway Greenhouse effect would develop.
39. Oxygen to Nitrogen ratio in atmosphere. If larger: Advanced life functions would proceed too quickly. If smaller: Advanced life functions would proceed too slowly.
40. Carbon dioxide level in atmosphere. If greater: Runaway greenhouse effect would develop. If less: Plants would not be able to maintain efficient photosynthesis.
41 Water vapor level in atmosphere. If greater: Runaway Greenhouse effect would develop. If less: Rainfall would be too meager for advanced life on the land.
42. Ozone level in atmosphere. If greater: Surface temperatures would be too low. If less Surface temperatures would be too high; there would be too much uv radiation at the surface.
43. Atmospheric electric discharge rate. If greater: Too much fire destruction would occur. If less: Too little nitrogen would be fixed in the atmosphere.
44. Oxygen quantity in atmosphere. If greater: Plants and hydrocarbons would burn up too easily. If less: Advanced animals would have too little to breathe.
45. Oceans to continents ratio. If greater: Diversity and complexity of life-forms would be limited. If smaller: diversity and complexity of life-forms would be limited.
46. Soil mineralization. If too nutrient poor: diversity and complexity of life-forms would be limited. If too nutrient rich: Diversity and complexity of life-forms would be limited.
47. Seismic activity. If greater: Too many life-forms would be destroyed. If less: Nutrients on ocean floors (from river runoff) would not be recycled to the continents through tectonic uplift.
(To give a balanced opinion of these contants, we should mention that some scientists have challenged the supposition that these parameters are not necessarily constant over the long time the Universe
