D. Fields

Image credits:

• Banner abstract-technology-spiral-wave-pattern-line-1174718-pxhere.com

• D.1 Gravitational fields: By Event Horizon Telescope, uploader cropped and converted TIF to JPG - https://www.eso.org/public/images/eso1907a/ (image link) The highest-quality image (7416x4320 pixels, TIF, 16-bit, 180 Mb), ESO Article, ESO TIF, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=77925953

• D.2 Photo by Johannes Plenio: https://www.pexels.com/photo/lightning-coming-from-the-sky-1119976/

• D.3 x70tjw, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons

• D.4 Photo by Flickr: https://www.pexels.com/photo/3-blades-windcane-157040/