Since there are hundreds of billions of galaxies (our Milky Way being just one)in the universe, there is an excellent chance that intelligent aliens exist somewhere in that incomprehensible vastness. However given the laws of physics it is impossible for any alien biological or mechanical entity to physically visit. However for over one hundred years, earth has been transmitting in analog and digital form over the last forty years meaningful radio waves. Theoretically an alien listening post has heard us. Those aliens may have in turn already linked with even more distant aliens. In fact there may be an existing chain of alien civilizations separated by distances that no biological or mechanical entity can transverse but communicate with each other via light speed digital transmissions. Perhaps sometime in the next fifty years earth computers will receive a truly wonderous transmission from far away.
Those signal monitoring aliens will show up one day and demand us to “Bring back Firefly!”