Note: The post I replied to was a reply to a post I made on page 2
The energy required is unobtainable. But energy requirement is just one aspect of the problem of traversing space in a feasible timeframe. But, the far more problematic issue is shielding requirement.
As we all know, the faster mass moves, the more kinetic energy the mass obtains. Let's say humans figured out how to produce such enormous energy to travel to the nearest star to our own within a lifetime. We're talking some serious speed. So much so that the speed becomes Relativistic speed (Google what relativistic speed is, for a better understanding)
Using equations of Mr. Albert Einstein's discovery of the Theory of Relativity, when traveling Relativistic speed, if even a speck of microscopic dust collided with the spaceship, the kinetic energy of the spaceship would release the energy equivalent of 28 Hiroshima atomic bombs... the spaceship would literally explode with the energy equivalent of 28 Hiroshima atomic bombs.
We're probably the only intelligent species that's capable of building/creating technology in the Milky Way galaxy, because not one signal has been detected. But, that doesn't mean intelligent species do not exist in our galaxy. When it comes to creating technology, physiology is critically important. Example: dolphins and whales are vastly more intelligent than most people think. They have far more complex linguistic than human language, yet will never be able to build technology due to their physiology, as well as their intelligence evolving in a vastly different environment than land dwelling species
Well, instead of continuing this already long post, check out the link below. And be sure to check out the video of an octopus enlisting help from a diver to catch food. Octopi have intelligence equivalent of an 85 iq.. that is average intelligence of humans. We may never find intelligent aliens elsewhere in the universe.. but that doesn't mean we haven't discovered an intelligent species.. we have found them on planet earth. And it's a god damn shame we humans are the reason the oceans will eventually kill most oceanic life.