Fermi Paradox: Understanding Drake Equation, Abiogenesis and Applications

Fermi paradox is the strange contradiction that we haven’t found a single trace of an alien civilization, even when the universe is so huge. Even if life is extremely rare, the scale of the universe must make life possible at a lot more places than just earth. The fact that humans haven’t observed any extraterrestrial life is the essence of the Fermi paradox.

Continue reading to learn more about the concept, drake equation, abiogenesis and application of Fermi paradox.

Fermi Paradox

A paradox is an apparently contradictory statement that, when investigated, may turn out to be well-founded or accurate. The Fermi paradox, in its most basic form, asks, “Where are the aliens?” The universe is so huge that we haven’t been able to observe more than 0.1% of it yet. Life on earth seems to have developed from non-living things in certain conditions that might not be specific to earth. Then it is probable that intelligent life must have originated elsewhere in the universe. But we don’t see any civilization or hear from them. So in the words of Fermi, “Where is everybody?”

Let’s do some quick maths to understand the Fermi paradox.

The universe has about \(10^{24}\) stars, and we know that 5% to 20% of those stars may be sun-like. So, even if we take only 5% of all those stars, it will be 500 billion sun-like stars. Out of these, we will need to have an Earth-like planet for life to exist.

An Earth-like planet means it has to have the proper size to have a solid surface and not too far or too close to its star so that it is in the habitable zone. The estimates are that about 22-50% of the stars have an Earth-like planet.

Taking the lower estimate, we still end up with at least 100 billion Earth-like planets. Even if we consider life extremely rare, only 1% of all Earth-like planets can develop life. We still have 1 billion life-developing planets. The number of life-supporting planets and planets in which life can evolve is still so large that it is difficult to imagine that none of them has intelligent life forms.

However, our ability to know about an alien civilization doesn’t simply depend on their existence but also on whether we can detect them. This might be why we don’t see evidence of alien civilizations. Dr. Frank Drake gave an equation to determine the possible number of detectable civilizations.

Drake Equation

The Drake equation tells us that the number of civilizations with whom we may be able to communicate is :

Where

is the average rate at which stars form in the Milky Way galaxy

is the fraction of those stars that have planets

is the average number of potentially life-supporting planets around a star

is the fraction of planets that could develop life at some point out of the planets that support life.

is the fraction of planets with life that develop civilization

is the fraction of civilizations that release signs that are detectable in space.

is the amount of time the civilization sends those signals into space.

This simple equation would be an easy answer. However, the values of parameters in this equation, like the fraction of planets that develop life, the fraction of planets that grow intelligent life, and the length of time for which the civilization emits detectable signs, are highly speculative. Moreover, when such speculative values are multiplied, the final result N gives little in the way of a firm conclusion.

Let’s look at what the Drake equation gives us through original and current estimates:

Parameter	Original Estimates	Current Estimates (low)	Current Estimates (high)
	1/year	1.5/year	3/year
	1/5 to 1/2		1
	1 to 5		0.2
	1		0.13
	1		1
	0.1	0.2	0.2
	1000 to 100,000,000 years	304 years	years
Result: N	20 to 50,000,000		15,600,000
Conclusion:	Observing such considerable uncertainties in the result N, Drake concluded that there are between 1000 and 100,000,000 planets with civilization in the Milky Way galaxy.	Since N is much lesser than one, it suggests that we are alone in the observable universe.	This suggests that more than 15 million detectable civilizations are there in the observable universe.

Some estimates take N to be much smaller than 1, which means we are alone. In contrast, other estimates for the parameters give outlandishly larger values, meaning the universe must be teeming with detectable life.

Therefore, the significance of the Drake equation is not in the value of the number N that it gives but in the parameters that are set. It provides the stepping stones over which our knowledge must be expanded. We need to understand the life on planet earth and elsewhere, along with its evolution, more firmly. This has raised the field of astrobiology. The Drake equation also focuses on some gaps in the study of life in the universe. One of the most important phenomena is abiogenesis.

Abiogenesis

Abiogenesis is the process by which life arises out of non-living matter. The leading hypothesis is that abiogenesis happens in different steps, creating an increasingly complex and self-replicating form of non-living and living matter.

Abiogenesis for hydro-carbon life forms requires four conditions:

1. Lipids must be formed to create cell membranes
2. Amino acids are needed for protein metabolism
3. Carbohydrates like sugar as a source of energy
4. Nucleic Acids such as DNA or RNA for self-replication

It is unclear at this point which among the four happened first. That is, whether life started from a lipid world or an RNA world. No concrete theory of abiogenesis exists yet. Parts and pieces of the abiogenesis puzzle are solved from time to time. Miller-Urey’s experiment showed that amino acids could be created in lab conditions by simulating the environment that the early earth had. Other experiments have shown likewise for lipids, but proper consensus regarding abiogenesis still doesn’t exist in the scientific community.

Abiogenesis is a vital link in the Drake equation and hence for the Fermi paradox. If we know how exactly abiogenesis happens, one of the parameters for the development of life will be more concrete than speculative. Thus, taking us a step closer to the solution to the Fermi paradox. An applicable theory of abiogenesis is still under construction in the scientific community.

Application of Fermi Paradox

The search for a solution to the Fermi paradox has led to the Drake equation, and area of studies like abiogenesis has gained more emphasis. A feasible solution to the Fermi paradox is “The Great Filter.” The basic idea behind the great filter is that there aren’t detectable civilizations in the universe because most life forms that get to a particular stage are destroyed.

There are three ways this could happen:

1. Abiogenesis is a step that planets hardly ever undergo. This means Earth has passed the great filter, but others haven’t, so there are no detectable aliens.
2. Intelligence is the step that very few life forms can undergo, so we have the same conditions as 1.
3. Any civilization formed by intelligent species is bound to fail due to over-exploitation, war, or other reasons at some stage, So we don’t see detectable life forms and that soon our life-form may end as well.

There are various other solutions proposed to the Fermi paradox, but none is conclusive. There might or might not be other life forms in the universe.

We hope this article has helped the readers understand the core concepts of the Fermi Paradox. For more conceptual knowledge on Physics topics and better grades, download the Testbook app today. Testbook enables you to prepare for competitive exams as well.