Year: 2022

PARAMETER SPACE. “Contra Ćirković, it certainly does not "tremendously limit the parameter space describing very advanced civilizations." Nonetheless, it represents a necessary first step toward more stringent and meaningful upper limits on Type iii Kardashev species.” https://lnkd.in/dKzsrBv View in LinkedIn

MANY TYPES OF SIGNALS. “Unlike solar neutrinos, however, the potential number of technosignatures is quite large and difficult to parameterize. In one early visualization of the search space for radio communication SETI, Wolfe et al. (1981) identified several relevant parameters: polarization, repetition rate of transmission, signal modulation, three spatial dimensions, central transmission frequency, and receiver sensitivity. “ https://lnkd.in/dKzsrBv View in LinkedIn

COSMIC HAYSTACK. “They then "compressed" the three dimensions of polarization, frequency of transmission, and signal modulation by considering only obvious, continuous signals searched for with receivers sensitive to orthogonal polarizations. Next, they compressed the three spatial dimensions into a single axis in terms of the number of targets or beams surveyed. They then graphically illustrated a three-dimensional "Cosmic Haystack" through which various SETI programs had hunted, looking for "needles." https://lnkd.in/dKzsrBv View in LinkedIn

RATIONALIZED PARAMETERS. “Similarly, Papagiannis (1985) described the "SETI search space" of two NASA SETI search programs for narrowband transmission in terms of the frequencies searched, fraction of sky surveyed, and instrument sensitivity. He distinguished between the Targeted search that parameterized the haystack in terms of the number of targets surveyed (discrete sources at good sensitivity) and a Sky Survey program parameterized in terms of sky coverage (i.e., a shallower search for any transmitters in the beam).” https://lnkd.in/dKzsrBv View in LinkedIn

DIMENSIONALITY. “Tarter (2006, 2010) described the search space as a "nine-dimensional haystack" in terms of three spatial dimensions, one temporal dimension (when the signal is "on"), two polarization dimensions, central frequency, sensitivity, and modulation.” https://lnkd.in/dKzsrBv View in LinkedIn

FARMER TALK. Working on a Herefordshire mixed sheep farm for a spell at 18, the farmer mysteriously advised me as we entered a field with two tractors to start ploughing: “go up the smooth and down the rough.” After a while, it made sense. Later in life, I discover on sanding wood a similar common truth which made me think of the farmer: sand with the grain, not across it. Common sense is not always common. View in LinkedIn

Majorcan sobrasada pickled meat in a cow stomach. View in LinkedIn

HAYSTACK. “This "needle in a haystack" metaphor is especially appropriate in a SETI context because it emphasizes the vastness of the space to be searched, and it nicely captures how we seek an obvious product of intelligence and technology amidst a much larger set of purely natural products.” https://lnkd.in/dKzsrBv View in LinkedIn

VARIOUS CRITERIA. “SETI optimists hope that there are many alien needles to be found, presumably reducing the time to find the first one. Note that in this metaphor the needles are the detectable signatures of alien technology, meaning that a single alien species might be represented by many needles.” https://lnkd.in/dKzsrBv View in LinkedIn

BUCKET PROBABILITIES. “Much of the SETI literature is dedicated to guessing or reasoning which haystacks might contain many needles. For instance, if we posit that extraterrestrial species are trying to get our attention and so have created obvious "beacons", then we can focus our efforts on those haystacks or parts of haystacks where needles would most obviously be left for us to find, i.e., we can identify which haystacks represent Schelling points in a game of mutual search—for instance, by guessing at "magic frequencies".” https://lnkd.in/dKzsrBv View in LinkedIn