When we think about finding extraterrestrial life, our minds often gravitate towards “earth-like” planets—those with conditions similar to our own. The reasoning is simple: life exists on Earth, so similar conditions elsewhere might also harbor life. However, the universe is vast, with hundreds of billions of galaxies, each containing billions, if not trillions, of stars. Most of these stars have planets orbiting them, leading to an astronomical number of potential planets—about a million billion billion. Given this enormity, it’s reasonable to assume that many planets could host life, including intelligent life.
Interestingly, basic physics and statistical principles suggest that intelligent extraterrestrial species are more likely to inhabit planets that are not like Earth and may differ significantly from humans. These species might be larger than us and live in smaller groups on smaller planets. This might sound surprising, especially since we only have one data point—ourselves. Yet, we can still make predictions about unknown aliens using statistical reasoning.
A fundamental concept in statistics is the difference between the properties of a typical individual and those of an individual in a typical group. For instance, most humans live in countries with populations exceeding 180 million, but most countries have populations under 6 million. Similarly, most religious people belong to religions with over a billion followers, while most religions have fewer than a million followers. This pattern holds true across various groupings, whether they are religions, sports teams, or even ingredients in a trail mix.
The key takeaway is that individuals are more likely to belong to larger groups rather than ordinary ones. If you’re unsure about which group you belong to, the largest groups are the most probable. For example, if you don’t know your blood type, you’re likely to be in a common group like O or A positive.
When it comes to intelligent life forms, we humans don’t know what kind of group we belong to. Statistics suggest that we should expect to be part of a large group of intelligent beings, meaning our species likely has a higher population than most others. This insight provides valuable information. For instance, larger populations require more space, so Earth, with its high population, is probably bigger than most planets with intelligent life.
Additionally, smaller creatures need less space and energy, leading to higher population densities. That’s why there are more ants than elephants on Earth. Consequently, humans, with our high population, are likely smaller than most other intelligent species.
We should expect to be unusual among intelligent aliens in factors affecting population size. For example, easily available energy supports higher populations, so our sun might be hotter, brighter, and closer than those of most intelligent alien species. Our atmosphere might also be more transparent to our star’s light.
With a few more assumptions based on basic physics, researchers have made predictions: the population of most intelligent alien species should be below 20 million individuals; most planets with intelligent life should have less than 80% of Earth’s radius; and individuals of most intelligent alien species should be at least as massive as polar bears.
Instead of focusing solely on “earth-like” planets, a more intelligent approach might be to search for habitable planets that are slightly smaller, darker, and hazier than our own. In essence, we should consider ourselves the Manchester United of the universe, searching for the AFC Wimbledon among the stars.
Engage in a structured debate with your peers about the characteristics of intelligent extraterrestrial life. Divide into two groups: one supporting the idea that intelligent life is likely similar to humans, and the other arguing for significant differences. Use statistical reasoning and examples from the article to support your arguments.
Participate in a workshop where you will analyze statistical data related to population distributions on Earth. Apply these principles to hypothesize about the population sizes and characteristics of potential extraterrestrial civilizations. Present your findings to the class.
Write a short story or essay imagining a mission to a planet with intelligent life that differs significantly from Earth. Incorporate the statistical predictions and characteristics discussed in the article, such as smaller planets and larger alien species. Share your story with the class for feedback.
Work in groups to design a research proposal for a mission to search for extraterrestrial life. Consider the article’s suggestion to focus on planets that are smaller, darker, and hazier than Earth. Outline the objectives, methods, and potential challenges of your mission.
Participate in an interactive simulation where you can adjust planetary conditions such as size, atmosphere, and energy availability. Observe how these changes might affect the likelihood of hosting intelligent life. Discuss your observations and conclusions with your classmates.
Extraterrestrial – Originating or located outside of Earth or its atmosphere. – Scientists use radio telescopes to search for extraterrestrial signals that might indicate the presence of alien civilizations.
Life – The condition that distinguishes organisms from inorganic objects and dead organisms, being manifested by growth through metabolism, reproduction, and the power of adaptation to environment through changes originating internally. – The study of life on other planets involves understanding the conditions necessary for biological processes to occur.
Planets – Celestial bodies orbiting a star, massive enough to be rounded by their own gravity, but not massive enough to cause thermonuclear fusion. – The discovery of exoplanets has expanded our understanding of the potential for life beyond our solar system.
Statistics – The practice or science of collecting and analyzing numerical data in large quantities, especially for the purpose of inferring proportions in a whole from those in a representative sample. – In astrophysics, statistics are crucial for interpreting data from telescopes and understanding the distribution of galaxies in the universe.
Intelligent – Having or showing intelligence, especially of a high level, often used in the context of beings capable of complex thought and communication. – The search for intelligent extraterrestrial life involves looking for signs of technology, such as radio signals, that could indicate advanced civilizations.
Population – In statistics, a complete set of items that share at least one property of interest. – When studying the population of stars in a galaxy, astronomers use statistical methods to estimate the number and types of stars present.
Physics – The branch of science concerned with the nature and properties of matter and energy. – Quantum physics provides a framework for understanding the fundamental forces and particles that make up the universe.
Groups – In physics and mathematics, a set equipped with an operation that combines any two of its elements to form a third element, satisfying certain conditions. – Symmetry groups play a crucial role in the study of particle physics, helping to classify particles and predict their interactions.
Energy – The capacity to do work or produce change, existing in various forms such as kinetic, potential, thermal, and more. – In thermodynamics, the conservation of energy principle states that energy cannot be created or destroyed, only transformed from one form to another.
Species – A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. – In astrobiology, scientists speculate about the possible existence of alien species that could have evolved under different environmental conditions on other planets.
