Unless an alien civilization finds a way to break the speed of light, we won't likely be able to communicate or visit with each other. It simply takes too much energy to travel and too long to communicate.

I quote from the Interstellar travel wikipedia article:

There is some belief that the magnitude of this energy may make interstellar travel impossible. It has been reported that at the 2008 Joint Propulsion Conference, where future space propulsion challenges were discussed and debated, a conclusion was reached that it was improbable that humans would ever explore beyond the Solar System.[1] Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute, stated “At least 100 times the total energy output of the entire world would be required for the voyage (to Alpha Centauri)”.[1]

Perhaps if we discover something about the nature of our universe that we aren't yet aware of, we will be able to interact with alien life. For now, the possibility is quite remote.

I also have one, and I've both used a case and not. Like you, I do not make many calls on my iPhone. Mostly I use it for email, text messages, taking pictures and mapping. It does a great job at these tasks. I haven't experienced a dropped call, but I also don't hold the phone with my palm or finger bridging the gap in the lower left corner.

I put the bumper on. Like I said, I haven't experienced a dropped call, so I'm not sure what the bumper has done for me other than give me a little peace of mind.

Anyhow if you think it might be a problem put the bumper on, but you might not really need it.