Here's a summary of the probability for one of us to be here, using some rough estimates to illustrate the scale:
Cosmic Scale:
Stars with planets: Approximately 1 in 5 stars has planets. If we consider only stars likely to have habitable planets, this might drop to 1 in 20 or less.
Habitable Zone: Only a fraction of these planets would be in the habitable zone; let's say 1 in 100 for simplicity.
Planetary Conditions:
Earth-like Planets: Even within the habitable zone, the odds of a planet having all the necessary conditions for life (like Earth's specific composition, atmosphere, etc.) might be 1 in 10,000 or even less.
Moon's Size and Distance: The Moon is just the right size and distance to stabilize Earth's axial tilt, which in turn stabilizes our climate over geological timescales. This stability was likely crucial for the evolution of complex life. Let's say, for argument's sake, the odds of having such a moon might be another 1 in 1000.
Life's Emergence:
From Non-Life to Life: The probability of life emerging on a suitable planet is unknown but could be as low as 1 in 10^20 or more, considering the complexity of chemical reactions needed.
Evolution to Complex Life:
From Simple to Complex: The evolution from simple organisms to something like humans involves countless steps of mutation, selection, and survival. If we simplify and say each major evolutionary leap has a 1 in 100 chance, and there are perhaps hundreds of such steps, we're looking at 1 in 10^200 or more.
Human Lineage:
Genetic Lottery: For each generation, the odds of specific sperm and egg meeting are about 1 in billions. Over thousands of generations, this compounds; for 1,000 generations, it could be 1 in 10^3000 if we're very conservative.
Historical and Personal Events:
Survival and Choices: If we consider each significant historical or personal event that had to go "right" for you to exist, each with a 1 in 10 chance, for 100 events, that's another 1 in 10^100.
Putting these together in a simplistic model:
1 in 20 (stars with planets)
1 in 100 (habitable zone)
1 in 10,000 (Earth-like conditions)
1 in 1000 (appropriate moon)
1 in 10^20 (life from non-life)
1 in 10^200 (evolution to humans)
1 in 10^3000 (specific genetic lineage)
1 in 10^100 (historical/personal events)
This gives us an extremely rough estimate of:
1 in 10^(3321.120)
This number is so large it's beyond comprehension, effectively making the probability of your specific existence so low that calling it a "miracle" is not just poetic but a practical way to express the scale of improbability.
Remember, these numbers are vastly simplified, and the real probability might be even more mind-boggling, but this gives a sense of why such an event might be described in such terms.
YOU are a miracle.
Silvia Hartmann
2025
|