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[An] upcoming study in The Astronomical Journal, which we learned about from MIT Technology Review, suggests humanity has barely sampled the skies, and thus has no grounds to be cynical. According to the paper, all searches for extraterrestrial intelligence, or SETI, have examined barely a swimming pool's worth of water from a figurative ocean of signal space. "We haven't really looked much," Shubham Kanodia, a graduate student in astronomy who co-wrote the study, said during a NASA "technosignatures" workshop in Houston, Texas on September 26.
[...] In their study, Kanodia and his colleagues built a mathematical model of what they consider a reasonably sized cosmic haystack.
Their haystack is a sphere of space nearly 33,000 light-years in diameter, centered around Earth. This region captures the Milky Way's bustling core, as well as many giant globular clusters of stars above and below our home galaxy.They also picked eight dimensions of a search for aliens — factors like signal transmission frequency, bandwidth, power, location, repetition, polarization, and modulation (i.e. complexity) — and defined reasonable limits for each one. "This leads to a total 8D haystack volume of 6.4 × 10116m5Hz2s/W," the authors wrote. That is 6.4 followed by 115 zeros — as MIT Technology review described it, "a space of truly gargantuan proportions."
Kanodia and his colleagues then examined the past 60 years' worth of SETI projects and reconciled them against their haystack. The researchers determined that humanity's collective search for extraterrestrials adds up to about 0.00000000000000058% of the haystack's volume. "This is about a bathtub of water in all of Earth's oceans," Kanodia said. "Or about a five-centimeter-by-five-centimeter patch of land on all of Earth's surface area."
Those numbers make humanity's search efforts seem feeble. But Kanodia views it as an opportunity — especially because modern telescopes are getting better at scanning more objects with greater sensitivity and speed. For example, he said, a 150-minute search this year by the Murchison Widefield Array covered a larger percentage of the haystack than any other SETI project in history.
Related: Stephen Hawking and Yuri Milner Announce $100 Million "Breakthrough Listen" SETI Project
Narrow SETI Targets by Looking at Places Where Earth Transits can be Seen
Either Stars Are Strange, or There Are 234 Aliens Trying to Contact Us
New Theory Suggests Radio Bursts Beyond Our Galaxy Are Powering Alien Starships
A New Theory on Why We Haven't Found Aliens Yet
Russian Physicist Proposes New Solution to the Fermi Paradox
Are We Alone? The Question is Worthy of Serious Scientific Study
(Score: 4, Interesting) by JoeMerchant on Thursday October 11 2018, @03:00AM (2 children)
There's a half acre of grass back there, all within 300' of my door, and I see evidence of moles, but only twice in five years have I ever actually seen a mole (and those only because our cat caught them...) Also underground are wasps, once a hive of bees, and all manner of other things that I can only begin to guess at. All within 2 minutes' walk of my door and 6" of the surface. Then there are things theoretically visible but still relatively unknown in the trees above. Humanity as a whole has taken enough interest in similar places to my backyard that we can make educated guesses about what the readily available evidence is telling us, but it would be several major lives' work of an undertaking to completely catalog all the life above and below ground just within 300' of my door.
By comparison, the Earth is 5 orders of magnitude bigger in diameter (15 orders of magnitude in volume), and all of humanity is just barely beginning to scratch the surface of understanding what's here, in our "backyard."
The solar system is a little more sparse, but there are millions upon millions of objects larger than my backyard there - Jupiter alone is about 11 times the Earth's diameter, well over 1000 times the Earth's volume - another 3 orders of magnitude just to cover Jupiter, and to completely cover the solar system would be yet another 18 orders of magnitude, for a total of 36 orders of magnitude bigger than my backyard - which, I might assert, could keep all the effort poured into SETI completely occupied for years just figuring out, exactly, what's going on in it. Expand to this 33,000 light year diameter and that's another 21 orders of magnitude in volume for a grand total of 57 orders of magnitude bigger than my already unknowably large backyard.
Granted, we're fast approaching a population of 8 billion, and that's a big number, but if we divide and conquer this search space, that's only 10 orders of magnitude, leaving each and every one of us 10^47 backyards to search.
Repeating the most insightful Douglas Adams quote: Space is big...
🌻🌻 [google.com]
(Score: 2) by bradley13 on Thursday October 11 2018, @08:37AM (1 child)
There are really three categories to consider:
- A technological civilization that actively wants to be found. They would broadcast high-powered, focused signals at specific wavelengths dictated by physics. They would broadcast to all nearby stars. Our current SETI programs would almost certainly detect these signals.
- A technological civilization that is not actively trying to be found. Like ours - we are not pinging all the nearby stars with MW transmitters. It's all well and good to talk about "I Love Lucy" broadcasts, but they will disappear into the background noise more than a couple of light-years out. Our current SETI programs are not even capable of detecting our own civilization, if it were around another star!
- Life that is not a technological civilization. How would we know if there are, for example, algae on a planet around another star? We don't have the technology to detect life that far away, even assuming we really know what to look for.
It's not about the search space - that's a red herring. If a civilization actively wants to be found, it's pretty clear what kind of signal they would send. The problem is: why would any civilization invest the time and effort to do that?
In the end, the only way to find out what it out there, is to go look.
Everyone is somebody else's weirdo.
(Score: 2) by JoeMerchant on Thursday October 11 2018, @01:23PM
As a civilization, we've only made a couple of very weak attempts at being found, some unimaginably tiny fraction of the space-time search space covered by "here we are" signals.
The magnitude of the search space is not a red herring - even if we, as a society, attempted to beacon "we are here" to the universe with one will and 20% of our GDP, it will take much longer than we have been a technologically capable society for that message to reach the first miniscule fraction of potentially habitable objects in the proposed search space. In my 10^47 analysis above, I neglected the other important component of space-time: time.
🌻🌻 [google.com]