The free space path loss from Earth to Alpha Centauri (4.4 ly) is ~345 dB at 100 MHz (FM broadcast). Our broadcast signals, with their relatively non-directional radiation patterns, are well below the thermal noise floor long before they reach anyone who might be listening for them.
UHF television broadcasts fare even worse because they have a much wider bandwidth and an even greater free space path loss.
While I cannot put a label on it right now (but surely it has a name, read about it somewhere), it is some kind of paradox that sufficiently advanced civilizations will broadcast themselves openly and detectably only for a very very tiny fraction of time (tens of years are nothing on intergalactic, interstellar or even planetary scale).
We quickly learned that blasting long-wave analog voice signals to the skies and expecting the reflection behind the horizon is pretty inefficient and moved to shorter, shorter and shorter waves. Not only you don't need to blast local radio stations in local language to the other side of the planet, having hundreds of computer wireless networks in one apartment building means that it actually shouldn't broadcast more than a few walls away in order for multiple networks to coexist even with time-division multiplexes and collision avoidance magic.
So, in about a hundred years, we discovered RF, we then started by blasting long-wave radio stations using ionosphere as a mirror, gradually moved to more and more local frequency bands, we then launched satellites to wirelessly ping across the ocean, only to hide the signals back under the sea and ground using fiber optics for practical reasons (bandwidth, latency), we went from analog to digital and we started encrypting just about everything. In the end, we will produce mostly random noise with ultrashort reach.
Next step - we will enclose Sol with Dyson sphere and disappear completely :)
It's not a paradox but it's based on our own techonlogical progression which is weird.
We are as a species 200-250,000 years old.
For most of that time we did absolutely fucking nothing as it seems.
Even for the recorded history which if we take the past 10,000 years then we still didn't made much progress as we did in the past 100.
And the weird part is that we still have small pockets of population living like our ancestors 200K years ago.
In 100 years we went from horses to cars, to rockets and spaceships to the internet and computers small enough to fit in our pockets.
The 20th century was weird as fuck as far as scientific progression goes.
And anyone recalling the film 2001 will know what signals they'll be picking up ...
(for those who haven't seen it, 'they' receive images dating from the 1930s or thereabouts with a certain someone making what is today, an unacceptable (for most of us one hopes) salute)
The same thing will happen that happened in the movie?
A bunch of idiots with "hitler is alive in space" signs on the streets.
What exactly would happen? You really think that the events in Charlottesville were because of Hitler? the KKK predates the Nazi party by over half a century.
Eugenics was considered a progressive theory in the late 19th and early 20th century.
Anyone who simply defines the protestors as Nazis is either intentionally pushing a hyperbole or is negligently oversimplifying the situation.
Firstly, I am not an American so while the Charlottesville clashes might be the most proximate case of ’alt-right’ ’protest’/parading/provoking it is (sadly) far from unique. Reactionary, nationalistic, and populistic sentiment seems to be coming to the fore pretty much everywhere in the Western sphere.
Secondly, I tend to agree that the term ’Nazis’ is... inaccurate. Deserved, earned, maybe even desired by the paraders themselves but fundamentally inaccurate. They synthesise their ideology down to a kernel of intolerance and racism and reach the conclusion that they are the natural successor in an unbroken line of descent from the ’cool’ Nazis, and thus they claim and are accorded the mantle. However national socialist ideology was far more complex, and the Nazi party's structure far more evolved, than these little folks have.
UHF television broadcasts fare even worse because they have a much wider bandwidth and an even greater free space path loss.