The Long Delay Echoes

The subject here is a scientific mystery that was well documented by European scientists in the 1920s and 1930s, well before any man made objects were launched into outer space, and then was largely forgotten. The phenomenon has since apparently disappeared, although anecdotal reports still pop up from time to time, and a low level of interest persists. We are discussing it here, because although no one knows for sure what caused the Long Delay Echoes, one plausible explanation is Bracewell Probes. The Long Delay Echoes (LDEs) just possibly might be a clue to how to find such a probe.

Some Basic Background You may Wish to Skip

 I'm sure you know that radio waves generally travel at the speed of light, and can be bounced off of various surfaces and also off the Earth's ionosphere if the radio wavelength is long enough. The speed of radio waves can be a bit slower if they are traveling through a medium such as a plasma or water, but generally the speed is not much less than the 300,000 kilometers per second we are used to. That means, if we send a radio signal out, and see it come back to us, then to calculate the distance to the reflector, we divide the time delay in seconds by 2 (since it went out and back), and then multiply by 300,000 kilometers per second to get the distance. Then, if we send out a radio signal and it comes back 2 seconds later, it must have traveled 300,000 km each way, or most of the way to the Moon. Amateur radio operators often enjoy bouncing their signals off the moon, which generally exhibits a very weak echo delayed about 2 and one half seconds. Strong echoes, or echoes delayed longer than 2.5 seconds, are not moon echoes.

Since the 1960s, there are many radio repeaters in Geosynchronous orbit, but the round trip delay is much shorter than the moon -  less than half a second, and you generally won't see a satellite echo at all unless your signal parameters are just right - and probably illegal.

Speculation - Hot Jupiters as Expended Batteries

Hot Jupiters are large planets – about the size of Jupiter or larger - that orbit very close to their star.  They comprise the upper left corner of this plot.   A year on one of these planets is only a few days, or even less. These planets are relatively easy to discover because of their large and short-period effect on their star's motion and a much higher probability of transit, so the statistics we have on extrasolar planets are skewed a bit toward this type of planet.  Nevertheless, they appear to be fairly common, though are no longer in the majority of the 843 2030 exoplanets catalogued to date.

Exoplanet Orbital period vs. age of host star

Hot Jupiters were a surprise to astronomers when first discovered, although Otto Struve had speculated on their existence in 1952, arguing that they were the only planets detectable by ground based telescopes. Hot Jupiters were not a real paradigm-buster, but were unexpected, because they can't form that close to the star -  it's like trying to get steam to condense on a hot soldering iron. Hot Jupiters have to form much further out from their star, and then migrate inward. There are plausible models for how this could happen fairly quickly as a result of complex tidal interaction with a disk of dust still surrounding the star shortly after it forms.  Such a natural migration may take only a few million years, but it has to happen early or there won't be enough of a disk to interact with.  What astronomers would really like to do is catch one of these planets in the act of migrating, but that will require a bit of luck and probably better telescopes.

The Natural Philosophy of Queerer and Queerer

A man's got to know his limitations.

--- Harry Callahan in Magnum Force 

A bit about Haldane's Law, and what it means about the search for other minds in the cosmos.

Haldane

You might recall that in our first post, there was a quote from the great Enlightenment thinker David Hume.  To paraphrase, all we can understand is what we have felt - either internally or externally.  The essential point is that when faced with something unfamiliar we interpret it in terms of the familiar.  We discover the universe in small steps.  Big conceptual leaps are rare, and even they depend strongly on what the "internal sense" has long known.

J.B.S. Haldane (1892-1964) was a distinguished evolutionary biologist and geneticist.  His Law is most often stated as:

I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. The universe is not only queerer than we suppose, it is queerer than we can suppose.

A lifelong study of the evolution and diversity of life on Earth alone could easily have guided Haldane to that conclusion. We are still making sense of the biosphere that is right here in front of us, with the textbooks scrapped and rewritten on a regular basis.

Let's say Haldane was right. We believe we anticipate strangeness, but even the strangeness is strange. What could be stranger than a non-human intelligence, particularly a sophisticated one? Haldane says we can't meaningfully speculate about how strange they could become, and in ways we can't imagine. An alien being isn't just going to offer you a cup of coffee and then tell you about Seven Habits of Highly Effective Cosmic Guardians. Or it might, and then eat you.
Now that's discouraging. If Haldane was right, how can we know what to look for if we are in search of other minds in the universe? We might be looking straight at them and seeing nothing.

In fact, I would bet that we are doing just that. In his excellent book, The Eerie Silence, Paul Davies offers a different slant on the critique of UFO reality - that the UFO mythos taken as a whole isn't strange enough. Davies would fully expect something much weirder, not a phenomenon that falls right in line with millennia of folklore. There are those who would argue that UFOs are in fact plenty strange, but I think Davies has a point. If what is going on is something we can understand or even clearly define, then it's probably not aliens.
And yet when we talk about our first encounter with a non-human intelligences, we often think in terms of Hollywood fantasies like The Day the Earth Stood Still. Klaatu is a mythical man very much of Earthly making, and his landing on the Washington Mall only makes far too much sense to us. Why haven't they landed on the White House lawn? They already did - in our imaginations, which is likely as close as "they" will get. We are going to have to get way beyond that sort of scenario

So, if we are to form any hypotheses, or even conjectures, so we know what to look for when go in search of Other Minds, what hope do we have in light of Haldane's law? I don't have a clear answer, but perhaps we can formulate it in terms of our own limitations, and look for the silence behind our blind spots. What can't we see, and why?  

I am hopeful. Experience shows that we humans can eventually, over generations, get our arms around some pretty strange ideas, primarily using our talent for abstraction. For example, the very odd idea of a black hole was fished out of the mathematics of Einstein's equations decades before the first solid observational evidence that such things existed. By the time astronomers were ready to go looking for black holes, the theorists already had a fair idea of what to search for. Now there is evidence for many billions of black holes all over the universe and they are well incorporated into the astronomical paradigm.

The other bit of hope is that maybe Haldane's law is limited, and doesn't really hold for alien intelligences. Perhaps the constraints on the evolution of sentient life are so tight that we all end up resembling each other in important ways. Perhaps. But don't bet on it.

Dream of the Open Channel by Paul Carr is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.