Earth is our one and only home. As Carl Sagan said (Pale Blue Dot: A Vision of the Human Future in Space), “On Earth, everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.”.
But will we ever leave our home and visit other stars in the future?
Our galaxy, “The Milky Way“ is a barred spiral galaxy (a spiral galaxy with a central bar-shaped structure composed of stars) some 100,000-120,000 light-years in diameter, which contains 100-400 billion stars. It may contain at least as many planets as well.
Our Sun (the Solar System) is located within the disk, about 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm.
As a guide to the relative physical scale of the Milky Way, if it were reduced to 100 meters in diameter, the Solar System, including the hypothesized Oort cloud, would be no more than 1 millimeter in width, about the size of a grain of sand. The nearest star, Proxima Centauri, would be only 4.2 mm distant.
Alternatively visualized, if the Solar System out to Pluto were the size of a US quarter (25 mm in diameter), the Milky Way would have a diameter of 2,000 kilometers, an area approximately one third the size of the United States.
As Douglas Adams pointed out, “Space is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.”
So, will we ever leave our home and visit other stars in the future?
The video below contains some possible answers to that very question.
At the end of the video, Michael also talks about the “Fermi Paradox”.
The Fermi paradox (or Fermi’s paradox) is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity’s lack of contact with, or evidence for, such civilizations. The basic points of the argument, made by physicists Enrico Fermi and Michael H. Hart, are:
- The Sun is a typical star, and relatively young. There are billions of stars in the galaxy that are billions of years older.
- Almost surely, some of these stars will have Earth-like planets. Assuming the Earth is typical, some of these planets may develop intelligent life.
- Some of these civilizations may develop interstellar travel, a technology Earth is investigating even now (such as the 100 Year Starship).
- Even at the slow pace of currently envisioned interstellar travel, the galaxy can be completely colonized in a few tens of millions of years.
According to this line of thinking, the Earth should already have been colonized or at least visited. But no convincing evidence of this exists. Furthermore, no confirmed signs of intelligence (see Empirical resolution attempts) elsewhere have yet been spotted in our galaxy or (to the extent it would be detectable) elsewhere in the observable universe. Hence Fermi’s question, “Where is everybody?”
You can also read a very good article contains all possible answers to the Fermi Paradox on waitbutwhy.com.