Month: September 2022

NOISE. “There is also the issue of recognizing a needle when one finds it, and not mistaking it for a particularly odd piece of straw. Communication SETI typically seeks signals so obviously artificial that there will be no doubt that the search has succeeded.” https://lnkd.in/dKzsrBv View in LinkedIn

ACUITY. “Artifact SETI seeks astrophysical anomalies and exotica that are consistent with predictions for alien technology, but may not be dispositive of such technology. Here, the metaphor breaks down somewhat, but we might interpret the needles and straw in these haystacks to be hard to distinguish. Finding such maybe-needles nonetheless helps communication SETI efforts to narrow down which parts of their haystack to focus on to find more unambiguous needles.” https://lnkd.in/dKzsrBv View in LinkedIn

TIME FUNCTIONAL. “A given telescope and instrumentation performing a survey of a given type will take some amount of time to complete a survey for a given sort of technosignature down to a given sensitivity. Intuitively, one would like to define a survey speed—i.e., haystack volume surveyed per unit of time—that was more or less constant throughout the survey and described the haystack volume searched to date as a linearly increasing function of integration time or telescope time.” https://lnkd.in/dKzsrBv View in LinkedIn

SEARCH SPEEDS. “The figure of merit one chooses thus depends on the haystack one is searching and how one is searching it; because different searches historically have had very different search methodologies—even among narrowband radio searches at the same wavelengths—it can be difficult to compare their relative search speeds.” https://lnkd.in/dKzsrBv View in LinkedIn

TARGET SENSITIVITY. “This will also be true with haystacks in general: the size, shape, and dimensionality of the haystack—and one's completeness in searching it—will necessarily depend on the sorts of needles one is searching for.” https://lnkd.in/dKzsrBv View in LinkedIn

PRIORITIZATION. “As we have seen, the choice of the number of dimensions for a haystack depends on the method used, and for many surveys, multiple dimensions can be "collapsed" into a single dimension, simplifying the problem. For our present purposes, we choose the following (not necessarily orthogonal) dimensions of a radio communication SETI haystack. (See criteria).” https://lnkd.in/dKzsrBv View in LinkedIn

LIMITATIONS. “Calculating search completeness requires defining the boundaries of the search; in many cases, one can always look harder for ever rarer or more subtle or more extreme events. The huge range of potential technosignatures also means that one survey cannot hope to be sensitive to all of them, requiring searchers to hypothesize a particular form of signature that they can put interesting limits on with their survey.” https://lnkd.in/dKzsrBv View in LinkedIn

THE CALCULATION. “To illustrate a haystack calculation, we have chosen a particular set of haystack dimensions that might exemplify any particular narrowband radio search with an eye toward determining whether we can yet rule out large numbers of narrowband transmitters in the solar neighborhood (that is, determining a rigorous—if weak—upper limit for SETI).” https://lnkd.in/dKzsrBv View in LinkedIn

THE SAD REALITY. “The total volume of Earth's oceans is approximately 1.335 × 10(21) liters, meaning that the total searching done to date is equivalent of ~8000 l of seawater, which is somewhere between the volumes of a large hot tub and a small swimming pool.” https://lnkd.in/dKzsrBv View in LinkedIn

WOEFUL COMPLETENESS. “We show that these assumptions allow us to do our calculation analytically, and we get a result very similar to that of another haystack, as calculated by Tarter et al. (2010): our current search completeness is extremely low, akin to having searched something like a large hot tub or small swimming pool's worth of water out of all of Earth's oceans.” https://lnkd.in/dKzsrBv View in LinkedIn