In The Creator and the Cosmos, author Hugh Ross advances the concept of the “Drake Equation” to include a total of 128 identified factors for habitable planets. He also calculated the probability estimate for each particular factor to be within an acceptable range to support life. Combining all probabilities (and compensating for dependencies) Ross calculates a probability for occurrence of all 128 factors to be a chance of 10-166. So even with a total number of planets in the range of 1022, the chance is less than 1 in 10144 (one in one thousand trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion trillion) that any such planet in the entire universe exists.
Numbers like 1022 planets and chances of 1 in 10144 are beyond our comprehension. We can write the numbers and count the zeroes, but they do not mean much. Therefore we need an illustration to understand these chances better:
-Imagine the total land surface of the USA , including Hawaii and Alaska , a total of three and a half million square miles.
-Also imagine one silver dollar. A silver dollar is about the size of a square inch.
-Now cover all the land surface of the USA with silver dollars.
-And start adding new layers of silver dollars to cover the surface again and again until a depth of 10 miles is reached everywhere.
-Now all the land surface of the USA is covered with silver dollars 10 miles deep everywhere.
-Next, imagine a single silver dollar marked with an X placed at random in this mass.
-Finally, blindfold a volunteer, drop him anywhere, send him to wander about until he chooses a point to dig into the 10-mile high pile, and grab only one coin.
-The chance of that person picking the silver dollar with the X is about 1 in 1025!
-Therefore, a change of 1 in 10144 is like repeating this experiment six times in a row, and each time selecting the X marked silver dollar – a virtual impossibility.
1Hugh Ross , The Creator and the Cosmos (2001 revised edition), chapter 16: Earth: a Place for Life.