This is the third book in the series that included 'The Theory of Nothing' the "The Universe Revealed.' My purpose in this new book is to more fully explain how science is actually done and how science fits into our culture along with religion and p...
That's a great question that's also hard to answer.
Up until just recently, there was no proof that Earth-like planets existed out there in our galaxy. Now that we know that they do for certain, we can speculate about whether there is another intelligent species like us out there wondering if they are unique in the universe.
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
I personally don't think that we'll find Vulcans and Klingons anywhere near us. The only reason that science fiction authors use aliens that are not that different than we are is because it's easier to depict them in movies. The chances that creatures like us developed on Earth-like nearby planets are very slim. Most of the exo-planets that orbit within the habitable zone of a main sequence dwarf star like ours are super earths, planet's that are substantially more massive than Earth. Many of them are tidally locked to their respective star. Any intelligent species that developed on one of these planets would not look like us.
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
However, there is a very good chance that a species like ours could have developed on an Earth-sized planet orbiting a single G-class main sequence star like our sun somewhere out in the vast universe of trillions of galaxies. The laws of chance would predict it despite the unique nature of our existence. The problem is that if they are in a galaxy far, far away, we won't know that they exist.
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
We are very unique in several ways. The first way is that our star, the sun, is a single G-class star. Most stars are part of a binary system. Planets orbiting such a star would have two suns. This would make the solar system that formed around such a star much different than ours.
Another way that we're different is that our planet has a large moon. The moon not only stabilized the rotational axis of our planet, it protected us from comet and asteroid bombardment. This provided us with consistent seasons that helped early humans to survive. It's doubtful that Homo sapiens would have evolved on an Earth with no moon. The climate would have been subjected to radical changes because of an unstable rotation.
Oops! This image does not follow our content guidelines. To continue publishing, please remove it or upload a different image.
The Earth's size also contributed to our evolution. The gravity is not too strong and not too light. It provided us with a nice atmosphere and allowed us to evolve with the ability to walk, freeing our ancestors to use their hands. A planet with a very strong gravity wouldn't have been as amenable to this, precluding tool making and eventual technological development.
Our solar system also contributed to human evolution. Jupiter has been a godsend because it has absorbed many comets and asteroids that could have wiped our ancestors out of existence. Jupiter also stabilized the inner planets, allowing Earth to orbit in the habitable zone. We could have ended up like Venus, a hellish planet that can melt lead or Mars, a cold barren world.
We humans are unique for another reason. We evolved over millions of years from a very complicated bunch of creatures that were unique in many ways. Climate change and extinction events forged our eventual emergence as the primary species on this planet. It's difficult to predict if such a complex evolutionary scheme could have happened on another planet, but if it happened here, it most certainly could have happened elsewhere, given the hundreds of trillions of possibilities. Unfortunately, we'll probably never know.
