Aliens are foreigners to their surroundings. The word is commonly used in law to denote non-citizens of the country of their whereabouts, and in fiction to denote extraterrestrial beings. The usage of the term is not limited to humans. Will them visit our earth a day, just like what happened in the movie “Extra-terrestrial”?
First of all, if aliens exist, they must be living at least hundreds of light year away. The only planet that can sustain life in the solar system is Earth, therefore we must rule out the possibilities of their existence in our solar system. However, if they do exist, they might not visit earth at all.
The reasons that aliens might not ever visit earth are as below:
1) Length of the universe
The universe is a very huge place. Our milky way alone, stretches across the universe for ten thousand light years (A light year is the distance travel by light in a year, light travels at speed 0f 300000 kilometre per second). Our earth looks like a tiny grain of sand in the milky way, not to mention the universe. If aliens are about to find us, they need to figure out where we are first, which is unlikely as there are over 200 million stars in our galaxy.
If aliens visit our earth, they might be infected by various diseases on earth. Human bodies are built to withstand the viruses on earth, our bodies can secretes antibodies and fight the disease, but aliens can’t. A mild cold infecting the aliens could be fatal to them. Aliens , in fact also carry unknown universal viruses, which may be fatal to human being too. To be wiped out by unknown diseases is the last thing we want, so do aliens.
3) The atmospheric pressure, temperature and force of gravity on earth
Our bodies are made to suit the atmospheric pressure, temperature and the force of gravity on earth well. If aliens visit our earth, they might be just tear apart by the pressure on earth. They will also be destroyed if they can’t suit the gravitational force on earth well.
4) Language barrier
If aliens are going to visit us, how do we communicate? If neither of us can break down the barier,
Then we can never communicate at all. If aliens know the fact that we can’t communicate with them, why should them visit us?
5) Civilization and technology
Aliens ae highly civilized. It is estimated that their technology is thousand of years ahead of us. They can travel freely in space, create wormholes and derives energy from the matter in universe. Why should they visit a our planet Earth whereas their technology is much more better than us.