Intelligent life is an extremely unlikely certainty, but it has occurred on Earth. Once an event has occurred, the probability of that event is 100%, no matter how unlikely it seemed at first.
The Drake Equation
Life on planet Earth comes in many shapes and sizes, and we generally know what we mean by life. Life is any system capable of feeding, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli.
Although certain characteristics are fairly universal to living things here on Earth, we must be careful how we define life. For example, if an alien were able to exist by pumping liquid methane through its body instead of water, would it no longer be a living being?
To reach that level, a civilization would need a star to orbit, a planet that suits it, a way to compete with other organisms for resources, and a way to survive without being wiped out by a freak meteorite impact.
Frank Drake pointed out that the same logic that can be used to calculate the number of students in a school can be used to calculate the number of civilizations in our galaxy whose electromagnetic emissions are detectable.
Suppose their planets are covered with lava or have no atmosphere or water. In this case, it is unlikely that life will evolve there.
Suppose you combine the fraction of planets that could host life with the fraction of intelligent life. In this case, you can predict how many alien civilizations we would see in the night sky.
R* is the rate at which stars suitable for the development of life are born
Scientists can predict how many stars form in the Milky Way galaxy each year, so we can use this to estimate how many alien civilizations we might reasonably see in the night sky.
Fp is easy to solve because we know that 90% of stars have planets. But only 300 million of them are at a reasonable distance from their stars and have the right mix of elements to support life.
There are two ways to estimate the number of life origins on Earth: Either we assume that life arose once the planet cooled sufficiently, or we assume that all life descended from a common ancestor.
Life on Earth may have arisen multiple times. However, the first life was more evolved and displaced the newly evolved simple bacteria to extinction. Thus, the probability of life on Earth becoming intelligent is very low.
I think that 70% of intelligent races will reach the point where they can communicate with other races. Since humans are unintentionally chatting with the universe, I think that number is probably much higher.
We won’t know how long our race will survive until we all die out, but the longer we are able to survive, the more likely we will continue to survive.
Based on these assumptions, there are 0 other civilizations in our galaxy. Let’s assume that the emergence of life and intelligence is certain. In this case, there are nine other civilizations in our galaxy.
According to the Drake equation, the sky could be completely silent or teeming with alien life. The more we can refine these numbers, the more confident we become about our chances of finding extraterrestrial civilizations.
The Drake equation is a tool used to estimate the number of intelligent civilizations in our galaxy.
While its exact significance is still being debated, the equation highlights the importance of factors like population size and lifetime in determining the likelihood of intelligent life forms.
In other words, it reminds us that there are many variables at play when it comes to finding extraterrestrial life — and that we may not be alone in the universe after all.