There are many factors to be considered if beings from outer space do visit us:
How will our fellow species on earth behave with them?
As pigheaded as we can be, we tend to forget that we are not the only living beings on this planet. There are millions of species ranging from the great whale, to the parasite Mycoplasma Genitalium or even the smallest microbes in our environment.
What if the aliens’ first visit was in the Amazon jungle or in the ocean which covers about 70% of our earth surface? In the event they are bit by a deadly snake or chased by a white shark, wouldn’t they consider our species very hostile?
Wouldn’t they be far more advanced or have a superior intelligence?
Over the years we have scanned different galaxies and observed different planets with the help of great telescopes. But we were able to find very few planets where life forms are possible. So if aliens do arrive on earth we can safely assume that they are far more technologically advanced, cause not only were they able to successfully locate us but also plan and travel such light years to reach us. There is a definite possibility that such intelligent beings learn our ways of life in a quicker way than we ourselves would without our detection.
Shouldn't we consider such beings with supreme intelligence threat to human race?
Humans have the most developed brain among all species on the planet. On account of our great intelligence and in the game of survival of the fittest we have overcome countless challenges and established great civilizations. By honing our skills we were able to hunt other animals and grow our own food by means of agriculture. We have trained animals with lesser intelligence to carry our loads or use them as a means of transportation. We have gathered and started breeding animals so that they can act as a source of our milk, leather, wool or meat. So coming back to this question, shouldn’t the human race fear those beings with apparently greater intelligence.
In case they come in peace can we trust them?
If some answers and comments on this question are to be referred, there is a opinion that if we were to be attacked the aliens would have done that when we were living in our caves. So most probably beings from outer space may come over for some cross-galactic cultural exchange or just to share their knowledge with us. But do we have the ability to enforce our trust on them or open our lives of lives to their galaxy. Are we tolerant ourselves to allow those aliens to live among us, following their own traditions and routines without us judging them.
What if their bodies don't cope with our ecosystem?
If aliens come from a place where the atmospheric pressure is far greater than on earth, they will surely experience very high blood pressures or other health related problems assuming their body is structured similar to the mammals on our planet. Similarly if the atmospheric pressure on there is lower than that of ours’ then they will experience the same feeling we experience at the depths of our ocean.
Also there is a possibility that the pathogens and viruses that exist on our planet can have a deadly effect on their bodies. Aliens with a lower or different immune system than that of ours can be faced with life threatening diseases the moment they arrive on earth, thus reducing our chances of having any kind of interaction with them.
On personal note I believe we were among the luckiest to have atmosphere that promote life forms and it is very unlikely that there will be aliens at least a few light years from our planet.
