I doubt you would find any support in the scientific community that "invisible pink unicorns" are more likely to cause the reported phenomena than are potential ET visitors. That's just an intentionally silly remark intended to tabloidize the phenomenon. Natural phenomena and artificial, terrestrial objects have been effectively and indefinitely ruled out of the equation for a select few cases, particular those cases reported in the 40s and 50s, when we were just beginning to use chemical rockets as a means of propulsion -- not to mention the hundreds of thousands of reports made prior to any balloons or airplanes were ever flown, many of the sightings being by astronomers themselves (see here). Considering the age and size of the universe we are a part of, there is no reason to believe that we haven't been visited. In fact, as I demonstrated earlier, considering the age of Sun-like stars in the habitable zone of the Milky Way galaxy being a billion years older than the Sun, we should expect such visitation by now.
"How would they know we are here?" One might ask. Well, they wouldn't have to listen for radio signals, that's for sure -- a common misconception. Take the Terrestrial Planet Finder as an Earthly example of how to spot out areas of interest. The TPF will be launched sometime in the next 25 years. Surely, a civilization a billion years older than us would have created and utilized such technology many millenia ago. After all, look how far we've come in just 100 years, let alone a billion. You can count to 100 easily enough, but try to count to a billion. It would take you more than 30 years.
Another, more mathematically efficient way a civilization could explore and catalogue the galaxy would be with the help of self-replicationg probes, Von Neumann probes (Named after John Von Neumann, who devised the mathematical laws of self-replicating systems). These probes could be sent out to other stars to land on vacant moons and the like and use the raw materials available to them to make copies of themselves, which are then sent out to new destinations to continue the process. In this manner, a galaxy 100,000 light years across could be completely explored in about a half million years -- .05% of the billion year difference between the age of the Sun and the average age of the other Sun-like stars in the habitable zone of the Milky Way Galaxy.
"How would they know we are here?" One might ask. Well, they wouldn't have to listen for radio signals, that's for sure -- a common misconception. Take the Terrestrial Planet Finder as an Earthly example of how to spot out areas of interest. The TPF will be launched sometime in the next 25 years. Surely, a civilization a billion years older than us would have created and utilized such technology many millenia ago. After all, look how far we've come in just 100 years, let alone a billion. You can count to 100 easily enough, but try to count to a billion. It would take you more than 30 years.
Another, more mathematically efficient way a civilization could explore and catalogue the galaxy would be with the help of self-replicationg probes, Von Neumann probes (Named after John Von Neumann, who devised the mathematical laws of self-replicating systems). These probes could be sent out to other stars to land on vacant moons and the like and use the raw materials available to them to make copies of themselves, which are then sent out to new destinations to continue the process. In this manner, a galaxy 100,000 light years across could be completely explored in about a half million years -- .05% of the billion year difference between the age of the Sun and the average age of the other Sun-like stars in the habitable zone of the Milky Way Galaxy.
I'm not disputing the mathematical possibility of ET's existence, or even visitation (I remember visiting the Greenbank Radio Astronomy Observatory as a kid, and learning about the possibility then), but that still isn't proof.
You could easily say instead of von Neumann probes, the aliens are inconsequential energy beings while in space, and turn solid when they hit our atmosphere. That's the beauty of speculation about unknown (and perhaps unknowable) phenomena. You can ascribe any traits you want to it, and can't be proven wrong.
As for the invisible pink unicorns, who's to say they don't exist?
