标题： 地球探测地球：使用当今技术，能够从多远的距离探测到地球的 technosignatures（技术特征信号）？ 显示英文标题

标题： Earth Detecting Earth: At what distance could Earth's constellation of technosignatures be detected with present-day technology?

摘要： 地外文明搜索（SETI）领域致力于寻找“技术特征”，这些特征可能通过地外智能（ETI）可能创造的技术，提供地球以外生命存在的首个探测证据。 任何特定的SETI调查，如果没有检测到技术特征，应基于它本应能够检测到的技术特征类型，设定相应的上限；许多SETI搜索的灵敏度要求其目标源（例如戴森球或卡达肖夫II/III级无线电发射器）发出的功率远远超过人类已开发的技术水平。 在这篇论文中，我们转而将目光投向地球，通过仅考虑与2024年地球技术水平相当的传输和检测方法，最小化外推轴。我们使用当前地球上的仪器，评估了各种当代地球技术特征的最大可探测距离——包括无线电传输、大气技术特征、光学和红外信号以及太空或行星表面物体，并提供了一种首次全面的跨波长比较，以展示SETI技术工具箱的发展。 在这个框架下，我们发现地球的空间可探测特征在可探测性上跨越了13个数量级，其中间歇性的、针对天体的无线电传输（即行星雷达）在探测距离上比其最近的非无线电竞争对手高出$10^3$倍。 这项工作强调了地外行星技术特征可能表现出来的日益多样化的形式、人类对地球影响的复杂性和可见性日益增加，以及无线电频率在SETI中的持续重要性。 显示英文摘要

摘要： The field of the Search for Extraterrestrial Intelligence (SETI) searches for ``technosignatures'' that could provide the first detection of life beyond Earth through the technology that an extraterrestrial intelligence (ETI) may have created. Any given SETI survey, if no technosignatures are detected, should set upper limits based on the kinds of technosignatures it should have been able to detect; the sensitivity of many SETI searches requires that their target sources (e.g., Dyson spheres or Kardashev II/III level radio transmitters) emit with power far exceeding the kinds of technology humans have developed. In this paper, we instead turn our gaze Earthward, minimizing the axis of extrapolation by only considering transmission and detection methods commensurate with an Earth-2024 level. We evaluate the maximum distance of detectability for various present-day Earth technosignatures -- radio transmissions, atmospheric technosignatures, optical and infrared signatures, and objects in space or on planetary surfaces -- using only present-day Earth instruments, providing one of the first fully cross-wavelength comparisons of the growing toolbox of SETI techniques. In this framework, we find that Earth's space-detectable signatures span 13 orders of magnitude in detectability, with intermittent, celestially-targeted radio transmission (i.e., planetary radar) beating out its nearest non-radio competitor by a factor of $10^3$ in detection distance. This work highlights the growing range of ways that exoplanet technosignatures may be expressed, the growing complexity and visibility of the human impact upon our planet, and the continued importance of the radio frequencies in SETI.