The Fermi Paradox With Neil deGrasse Tyson – Where Are All The Aliens?

Here’s a sanitized version of the provided YouTube transcript:

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All right, you see that large W-shaped constellation right there? That’s Cassiopeia. Cassiopeia A emits a significant amount of radio signals; I actually listen to that quite often. It’s a remnant of a supernova. Since the birth of philosophy, we’ve never stopped wondering about the question: Are we alone? The ancient Greek philosopher Epicurus considered the universe to be the result of the movement of atoms and regarded it as highly likely that there were other worlds out there, possibly inhabited.

Since the time of the ancients, have we made any progress in answering this profound question? As NASA has explored our solar system and beyond, it has developed increasingly sophisticated tools to address our endless curiosity about the possibility of life existing elsewhere in the cosmos. Within our solar system, NASA’s missions have searched for signs of both ancient and current life, especially on Mars and Jupiter’s moon Europa. Beyond our solar system, missions such as Kepler are revealing thousands of planets orbiting other stars, fueling our imaginations further as we wonder if there are other civilizations out there, perhaps asking the same question: Are we alone?

The explosion of knowledge regarding exoplanets and decades of research on biosignatures have encouraged NASA to explore in a scientifically rigorous way whether life on Earth is unique. Beyond searching for evidence of microbial life, NASA is now exploring ways to search for life advanced enough to create technology. Unfortunately, so far, we only have one data point regarding the existence of life in the universe—here on Earth. However, that shouldn’t suggest that it can’t tell us anything about the possibility of life existing elsewhere.

If we could quantify the prevalence of life in the galaxy, it would be a significant factor. The best argument for increasing that stock value is as follows: When you took a biology class, you learned that the Earth is about four and a half billion years old. If you look at the earliest fossil evidence of life on Earth, it dates back to about three and a half billion years. Subtract those two numbers, and you get the time frame from the beginning of Earth to the first evidence of life—about a billion years. This means life appeared relatively quickly in the planet’s history.

Recent findings have pushed the fossil evidence of life back to about 3.8 billion years, with some evidence suggesting it might even reach 3.9 billion years. This reduces the time available for life to have formed on Earth, making it more likely that life could emerge given the right conditions. The faster life appears from a pool of chemicals, the more confidence we have that life is something that could happen under the right circumstances.

We also learned that the early solar system was not just a simple formation of the sun and planets; it was filled with debris scattered throughout space. This debris was gradually collected by the gravity of the planets, which would not have been a pleasant experience on their surfaces. The temperature of Earth’s surface during this period would have been too high for complex molecules to form. Computer models show that this period of heavy bombardment lasted around 600 million years, meaning it wouldn’t be fair to start the life clock at 4.5 billion years ago, as life had no chance of forming when the surface was molten.

Now, if we consider the timeline from four billion years ago to 3.8 billion years ago, we have narrowed it down to 200 million years, down from a billion years that was previously imagined. This further supports the idea that life could have formed relatively quickly. Just because we find it challenging to replicate this in the laboratory doesn’t mean nature has faced the same difficulties.

While evidence for the existence of alien life would be one of the biggest scientific discoveries of all time, evidence for intelligent alien life would top that. In 1961, American astronomer Frank Drake proposed a probabilistic argument to estimate the number of active communicative extraterrestrial civilizations in the Milky Way galaxy. More than half a century has passed since Drake stimulated scientific dialogue on the search for extraterrestrial intelligence, and now we have more insights into some of the factors of the Drake equation.

In a paper published in astrobiology, Adam Frank, a professor of physics and astronomy at the University of Rochester, discussed the uncertainties in the Drake equation. We have a good estimate of how many stars exist, but we didn’t know how many of those stars had planets that could potentially harbor life, how often life might evolve into intelligent beings, and how long any civilizations might last before becoming extinct. By applying new exoplanet data to the universe’s estimated 2 x 10^22 stars, it appears that human civilization is likely unique in the cosmos only if the odds of a civilization developing on a suitable planet are less than about 1 in 10 billion trillion. This incredibly small number suggests that other intelligent, technology-producing species likely evolved before us.

It may be that intelligence, as we define it, is rare in the cosmos. If we examine the fossil record, we see that many features of life have emerged independently across different species. For example, locomotion is a common trait; creatures like snakes manage to move without arms or legs. The ability to receive information at a distance—through smell, hearing, and sight—is also prevalent. Sight, in particular, has evolved independently in various forms, such as the fly eye, vertebrate eye, and octopus eye.

However, intelligence, as we have defined it, has not shown up in the fossil record, suggesting it may not be crucial for survival. In fact, one could argue that intelligence might even lead to extinction.

In the summer of 1950, Italian-American physicist Enrico Fermi, during a casual conversation about UFO reports and faster-than-light travel, famously asked, “But where is everybody?” This question became known as the Fermi Paradox, highlighting the contradiction between the lack of evidence for extraterrestrial life and the high probability of its existence.

What could explain this paradox? The concept of the “Great Filter” suggests that something is preventing non-living matter from evolving into lasting life. The failure to find extraterrestrial civilizations implies that there may be flaws in the arguments suggesting that advanced intelligent life is probable. The Great Filter acts to reduce the number of sites where intelligent life may arise to the few advanced civilizations we observe.

Economist Robin Hansen described a list of nine steps in the evolutionary path leading to the colonization of the observable universe. These steps include having the right star system, the emergence of reproductive molecules, simple single-celled life, complex single-celled life, sexual reproduction, multi-cell life, tool-using animals with intelligence, a civilization advancing towards colonization, and finally, a colonization explosion.

According to the Great Filter hypothesis, at least one of these steps must be improbable. If the improbable step is not in the past, it suggests that the challenges lie in our future, making our prospects for reaching interstellar colonization bleak. If earlier steps are likely, many civilizations should have developed to our current level, but none appear to have reached the final step, or else the Milky Way would be filled with colonies. Perhaps the final step is the unlikely one, and the only things keeping us from it are potential catastrophes, such as self-annihilation.

Hansen’s list, although incomplete, provides insight into the Fermi Paradox and attempts to answer the question: Are we alone in the universe? A growing number of people believe we’ve already answered this question due to recent UFO reports. However, eyewitness testimony and ambiguous video footage do not constitute extraordinary evidence to definitively answer this age-old question. To be respectful to those who believe we’ve been visited by extraterrestrial crafts, we will dedicate a whole video to this topic.

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This version maintains the original content’s essence while removing any informal language and ensuring clarity.