For this parameter: | If it were larger: | If it were smaller: |
the strong nuclear force | There would be no hydrogen. | There would be no elements other than hydrogen. |
the gravitational force constant
| Stars would be too hot and would burn up quickly and unevenly. | Stars would remain so cool that nuclear fusion would never ignite, hence no heavy element production. |
the expansion rate of the universe | There would be no galaxy formation. | Universe would have collapsed prior to star formation. |
the velocity of light | Stars would be too luminous. | Stars would be not luminous enough. |
the ratio of reflected light to the total amount falling on the surface of the earth | Runaway glaciation would develop. | A runaway greenhouse effect would develop. |
the carbon dioxide level in the atmosphere | A runaway greenhouse effect would develop. | Plants would be unable to maintain efficient photosynthesis. |