'None so blind as them who won't see!' Perhaps if these scientists were to examine Dr Steven Greer's Sirius Disclosure Project, they might get a different perspective on the matter. As for me, what I and one other witness saw in the sky over the Midlands of the U.K. one summer's evening back in the 1980s was not, and could not have been, any aircraft that I know of - and I am a mechanical engineer with an interest in avionics. I would not be surprised to learn of alien involvement somewhere along the line.

Can we expect our TV and Radio transmissions to be detected by any alien civilisation (or to detect theirs)? Are the transmissions not likely to be far too attenuated to be registered beyond a few light years away?

The problem with finding an intelligent species that's capable of producing their own versions of light, sound and other waves is that of the Universe's timeline. Mankind has only been around in it's present industrial state for about 100 years which is a blip on the overall time period of 15 billion years since the big bang and formation of stars. The chances of another lifeform overlapping our timeline so that we co-exist in the same point in time (in our ability to communicate via technology) is very tiny. That, more than the possibility of other Earth's is the primary reason we haven't heard from ET yet. And vice versa.

Scientists? Is Cornell part of the "Flat Earth Society"? There's evidence of ancient (1,000 ~ 15,000 years ago) highly advanced technology/civilization all over this planet. These so-called scientists from Cornell should watch a few episodes of "Ancient Aliens" on the History Channel or H2 (now in their 8th season) or read Erik Von Danican's book "Chariots of the Gods" published in 1968.

As to aliens finding something, the artice claims, "we need to give them time." Fermi might respond that we HAVE given them time. Earth has had life and the resulting oxygen rich atmosphere for two billion years. Planets elsewhere in our galaxy have had 10 to 12 billion years to get ready for this event. The oxygen shines even more brightly than our TV signals -- what are the aliens waiting for?

@Paul Nash, Consider that digital (which is superior to analog) signals coming from deep space probes require giant antennas, have very slow data speed and require lots of advanced error correction tricks. From that I would think there is not really any chance radio/TV broadcasting from Earth to be recovered at another star.

1500 years!! By then we will have probably spread out far enough and diversified enough that we will be indistinguishable from any space aliens that we might encounter. We may never find any and will only get false positives where we keep rediscovering ourselves. People who want to find life out there in space need to address it the Elon Musk way, not the Carl Sagan way.

Perhaps what they really meant was that Scientists will not be ready for contact for another 1500 years. Most people I know have a belief in something other than ourselves operating within our tiny insular world.

Ah, intelligence, that magical, mystical product of evolution, a process understood to gain traction generationally. So, creatures with shorter lifespans have had exponentially more generational iterations, within a set period of time, through which to evolve. While a human being lives ~75 years, some creatures on earth only live a day or less; given that lower orders are understood to have emerged millions of years before humans, and that that they live shorter lives, they've had exponentially many, many more generational iterations to evolve intelligence...yet they haven't; while humans, emerging so much later and generationally iterating at a much slower pace, have. How can we begin to approach grasping intelligence elsewhere in the universe when the manner by which we ourselves arrived at this capacity seems so...odd?

1,500 years? Humph! When I was a kid, I read the 1933 Universal encyclopaedia and in it was a "scientific" rendering of Phobos showing a landscape festooned with needle sharp mountains because there was no atmosphere to erode them. If they had looked at the Moon... They did have telescopes in 1933... A further thought. Imagine aliens whose "Adam & Eve didn't eat the apple? Do they want to find this crazy place?