Why Can’t We See Evidence Of Alien Life
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The Fermi Paradox: Where is Everybody?
In the vast expanse of the universe, it seems almost certain that there must be countless other planets teeming with life. This is the famous question asked by Enrico Fermi in 1950: “Where is everybody?” While conspiracy theorists claim that UFOs are visiting all the time and the reports are just being covered up, these claims aren’t very convincing. This leaves us with a real riddle.
The Abundance of Planets and the Possibility of Life
In the past year, the Kepler space observatory has found hundreds of planets just around nearby stars. If you extrapolate that data, it appears there could be half a trillion planets just in our own galaxy. If even one in 10,000 of these planets has conditions that might support a form of life, that’s still 50 million possible life-harboring planets right here in the Milky Way.
The Riddle of Earth’s Late Formation
Our Earth didn’t form until about 9 billion years after the Big Bang. Countless other planets in our galaxy should have formed earlier and given life a chance to get underway billions or certainly many millions of years earlier than happened on Earth. If just a few of them had spawned intelligent life and started creating technologies, those technologies would have had millions of years to grow in complexity and power.
The Absence of Evidence
On Earth, we’ve seen how dramatically technology can accelerate in just 100 years. In millions of years, an intelligent alien civilization could easily have spread out across the galaxy, perhaps creating giant energy-harvesting artifacts, or fleets of colonizing spaceships, or glorious works of art that fill the night sky. At the very least, you’d think they’d be revealing their presence, deliberately or otherwise, through electromagnetic signals of one kind or another. And yet we see no convincing evidence of any of it. Why?
Possible Explanations
There are numerous possible answers, some of them quite dark. Maybe a single, superintelligent civilization has indeed taken over the galaxy, and has imposed strict radio silence because it’s paranoid of any potential competitors. Or perhaps, the evolution of an intelligence capable of creating sophisticated technology is far rarer than we’ve assumed. After all, it’s only happened once on Earth in 4 billion years. Maybe even that was incredibly lucky. Maybe we are the first such civilization in our galaxy. Or, perhaps, civilization carries with it the seeds of its own destruction through the inability to control the technologies it creates.
More Hopeful Answers
But there are numerous more hopeful answers. For a start, we’re not looking that hard, and we’re spending a pitiful amount of money on it. Only a tiny fraction of the stars in our galaxy have really been looked at closely for signs of interesting signals. And perhaps, we’re not looking the right way. Maybe as civilizations develop, they quickly discover communication technologies far more sophisticated and useful than electromagnetic waves. Maybe all the action takes place inside the mysterious recently discovered dark matter, or dark energy, that appear to account for most of the universe’s mass.
The Future of Our Search
Within the next 15 years, we could start seeing real spectroscopic information from promising nearby planets that will reveal just how life-friendly they might be. And meanwhile SETI, the Search for Extra-Terrestrial Intelligence, is now releasing its data to the public so that millions of citizen scientists, maybe including you, can bring the power of the crowd to join the search. And here on Earth, amazing experiments are being done to try to create life from scratch, life that might be very different from the DNA forms we know. All of this will help us understand whether the universe is teeming with life or, whether indeed, it’s just us.
The Awe-Inspiring Possibilities
Either answer, in its own way, is awe-inspiring, because even if we are alone, the fact that we think and dream, and ask these questions might yet turn out to be one of the most important facts about the universe. And I have one more piece of good news for you. The quest for knowledge and understanding never gets dull. It doesn’t. It’s actually the opposite. The more you know, the more amazing the world seems. And it’s the crazy possibilities, the unanswered questions, that pull us forward. So, stay curious.
Discussion Questions
- How does the existence of countless other planets in the universe impact our understanding of the possibility of extraterrestrial life?
- What are some possible explanations for the late formation of Earth compared to other planets in our galaxy?
- Why is the absence of evidence for intelligent life in the universe considered a riddle?
- What are some dark and hopeful answers to the Fermi Paradox?
- How does our current approach to searching for extraterrestrial life limit our ability to find evidence?
- What role do advancements in spectroscopic technology and citizen science play in our future search for extraterrestrial life?
- How might experiments to create life from scratch contribute to our understanding of the abundance of life in the universe?
- How does the quest for knowledge and understanding of the universe inspire curiosity and drive our exploration of the Fermi Paradox?
Lesson Vocabulary
fermi paradox – a contradiction between the high probability of extraterrestrial life and the lack of contact with, or evidence for, extraterrestrial civilizations.
Example sentence: The Fermi paradox raises the intriguing question of why, if intelligent life is so likely to exist in the universe, we have not yet made contact with any other civilizations.
universe – all existing matter, including galaxies, stars, planets, and all other forms of energy and matter.
Example sentence: The universe is vast and mysterious, with countless galaxies and celestial bodies yet to be explored.
planets – celestial bodies that orbit a star and do not produce their own light, such as Earth, Mars, and Jupiter.
Example sentence: Our solar system is home to numerous planets, each with its own unique characteristics and potential for hosting life.
life – the condition that distinguishes living organisms from inanimate objects, characterized by growth, reproduction, and the ability to respond to stimuli.
Example sentence: The search for extraterrestrial life is driven by our curiosity to understand if there are other forms of life beyond Earth.
riddle – a puzzling question, problem, or mystery that requires solving or explanation.
Example sentence: The nature of dark matter remains a riddle for scientists, as they strive to unravel its elusive properties.
abundance – a large quantity or amount of something.
Example sentence: The universe is teeming with an abundance of galaxies, stars, and potential habitats for life.
possibility – the state or fact of being likely or probable; a potential or feasible outcome.
Example sentence: The discovery of liquid water on Mars has opened up the possibility of finding microbial life on the red planet.
evidence – facts, information, or signs that support a belief, claim, or hypothesis.
Example sentence: The fossil record provides compelling evidence for the existence of dinosaurs millions of years ago.
explanations – statements or reasons given to make something clear or understandable.
Example sentence: Scientists propose various explanations for the formation of black holes, each based on different astrophysical theories.
search – the act of looking or seeking something, often with the goal of finding or discovering.
Example sentence: Astronomers continue their search for habitable exoplanets beyond our solar system in the quest for understanding our place in the universe.
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- Categories: Earth & Space Science, TED Ed, Video Lessons
- Keywords: abundance, alien, evidence, explanations, fermi paradox, life, planets, possibility, riddle, search, universe
