Trillions?? Then it should be no problem to prove out just one, eh?
The universe is a very large place.
It would be nearly impossible to locate one for the exact same reason you feel it is possible. The large numbers can cause confusion.
Once you realize that when we consider space we must also consider time. Calculating the possibility that other life exist in the universe makes it almost a certainty. However, calculating the possibility that life forms would cross paths in both space and time that allowed proof the other existed makes it a virtual impossibility.
The key to accepting this is to acknowledge that space is virtually devoid of all matter. We fool ourselves by looking up at the sky on a clear night and seeing billions of objects. We see these as a 2-D picture with no real appreciation for the time that separates what we are seeing.
Given that the number 100 represents all of the known universe ask a scientist what part of that 100 is actual matter. Then ask the scientist the size of the universe in distance and then time.
Scientist measure distance in light years. One light year represents the distance light, moving at 186,000 miles per second, travels in 31,536,000 seconds, which is one year.
To calculate one light year in miles we multiply 31,536,000 seconds by 186,000, which yields 5.86 trillion miles.
The universe is very large. Recalling that one light year is nearly 6 trillion miles the observable matter in the universe is at least 93 billion light years across. For comparison, the diameter of a typical galaxy is only 30,000 light-years.
As far as time is concerned, the most precise estimate of the universe's age is 13.7 billion years.
What are the odds that different life forms would discover each other once you consider space or distance in “light years” and time in “years”?
Well no, it probably won't be, but it's not like going down to the street to the local auto parts, looking for that specific part.
In this case, great distances are involved. In order to prove this it will take more advances in technology, observation, and searching, and most of all, it will take time. Like those that dared sail across the oceans many years ago, it took time.
Look how long it took this species just to travel to our closest neighbor, the moon. What did that take, thousands of years of gawking at the moon for generations until we were able to actually make the trip?