The cosmic speed limit - or speed light travels in one year - is set at least according to early 21st century physics. I really don’t expect to see FTL (faster than light) travel developed but you can never say never.
In the world of science fiction FTL is naturally quite prominent since it allows for far more in the way of writing options although Joe Haldeman does a masterful piece of writing without it in “The Forever War.” So the general consensus of the big brain folks is that 186,000,000 miles per second is the limit. That’s it! No faster. To reach that speed you will need both incredible technology and energy supplies.
Does ET or the aliens from Close Encounters exist? Benevolent travelers exploring their neighborhood. Sort of a galactic version of Charles Darwin taking note on the various species that inhabit said neighborhood. Maybe the ones we are more familiar with that make for far better reading and use of special effects and the ones that are constant fodder for our real tastes - weapons and wars. Just think Spanish Conquistadors in a space ship with a bevy of high tech weapons.
From the history of our own planet the results of a technologically superior culture - especially one in need of raw materials and colonies - meets a less technologically advanced the outcome is a slam dunk. It is a constant pattern of history on the earth. No need to elaborate on it since the facts are clear from when social studies/histories veers away from the platitudes of rich White guys forming a nation and gets into the nitty gritty of our own nation and all those who preceded us.
Humans are not the only ones spoiling for a fight. Nature is the constant struggle - like in sports - of offense and defense. Predator and prey using various methods to tip the balance of power. Why they even occasionally war against their own for territory, mating and food sources. Not unusual. Earth is a violent planet. But nature plays a game of balance allowing all at least some degree of opportunity for survival. Some it may be short term registered in a million or so years and for others such as the hardy cockroach hundreds of millions of years. For humans it is about 6,000 years in view of some or in my belief system about 50,000 since we acquired our big brains and thus behavioral modernity. Many millions of years to reach that point.
So I have to make an assumption based on earth time experience regarding our own evolution to being - at least in our opinion - number one on the evolutionary pyramid. It was a brutal experience and a 7,000,000 year journey and maybe many millions more if you consider the emergence of mammals. Kill or be killed seems to have a bundle of validity in nature. First we have managed to annihilate species deemed a threat. Then we manage to annihilate as many of our own kind as possible. Then we Terri form our own environment for good or bad.
OK so now lets go 50 light years from earth. There are several thousand stars in just that small segment and many have earth like suns. Some may have life either primitive biological or more sophisticated on accompanying planets. Some may have planets where the industrial revolution is just beginning or where they managed to rape nature to the extent they ended their civilization. Some may have explored their own solar system. Some may need room to expand - a space faring Nazi regime.
My contention is there is a high degree of probability that any neighbors are really not that passive. To reach their own pinnacle of evolutionary dominance it was a hard fight with no quarter given to competing species or their own kind. Like ourselves they may talk the talk but somehow I doubt they will do the walk. Imagine what havoc humans of today would be capable of reaping on an alien civilization if we had FTL?
Now is this cosmic speed limit actually a sign of intelligent design? Did a “God” in her infinite wisdom put this in place to protect us from each other? I’m more of a nature theorist on this. Bless nature for the cosmic speed limit. But with that blessing remember the native populations of the Americas were protected for thousands of years my vast oceans. Just how did that turn out?