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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

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

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

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

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

WEAK UPPER LIMIT. “For instance, Griffith et al. (2015) put weak upper limits on the total waste heat across entire galaxies, concluding that out of 100,000 galaxies, none had a galaxy-spanning species harnessing more than 85% of the galaxy's starlight. This result might hardly be surprising given that this upper limit is near the extreme limit of what galaxy-spanning technology could accomplish.” https://lnkd.in/dKzsrBv View in LinkedIn

FALSE UPPER LIMIT. “Similarly, in SETI, the first upper limits will necessarily rule out only extremely obvious manifestations of alien technology, and may seem at first to "have no bearing on the question of the existence of" alien life.” https://lnkd.in/dKzsrBv View in LinkedIn

FALSE PREMISE. “But the reviewer is incorrect. It is not at all hard to imagine that prehistoric humans around the world performed just such an experiment, told others about it, and in so doing significantly advanced their understanding of the cosmos.” https://lnkd.in/dKzsrBv View in LinkedIn

SOLAR NEUTRINO SEARCH. “Any experiment such as this, which does not have the requisite sensitivity, really has no bearing on the question of the existence of neutrinos. To illustrate my point, one would not write a scientific paper describing an experiment in which an experimenter stood on a mountain and reached for the moon, and concluded that the moon was more than eight feet from the top of the mountain.” https://lnkd.in/dKzsrBv View in LinkedIn