Are There Aliens Among Us?

Some say we have been visited by aliens, even that they are living among us.  Lots of stories have been written with that premise.  Let's take a look at the obstacles aliens would have to overcome to get here, why they would bother in the first place, where they might come from, and how they could conceal themselves from us while living among us.

Getting here.  For aliens to get here, they would either need to travel in a generation ship or exceed the speed of light.  Everything we know about physics tells us that the latter is impossible.  A generation ship large enough to last thousands of years would be way ahead of our abilities, but still it would be possible.  But why here?  The odds of coming here are infinitesimal.  It looks like "V" is not too likely.

Why Bother?  What do we have that another race would be interested in?  Why go to all that trouble for little or no return?  Our planet was explored only when there was profit to be had.  What about "Pilgrims" in a generation ship running from wars or persecution?  Wouldn't they make themselves known and hope to be taken in?  It is really far-fetched to think that our resources are so valuable that another race would mount a planet-draining effort to steal our poop.

Where are they from?  It seems that this is the only planet in our solar system inhabited by intelligent(?) life, so any aliens would have to be from another star.  The nearest stars with planets are many light years away, but even if we concede that Alpha Centaurus has habitable planets, it's over four light-years away and would take many years to get here.  Again, why bother?

What do they look like?  It would be the height of arrogance to assume that aliens would look anything like us.  Any planet they came from would be unlikely in the extreme to be exactly like ours, and even if it were, evolution might take any number of different paths.  Aliens probably would not be able to even survive on the Earth.

However, even though we most likely never have and never will be visited by aliens from outer space, we have living next door to us a race which may be smarter than we are - Cetaceans!  They, at least, have never destroyed their environment, they don't fight wars, and they are even nice to their neighbors, us.