{"id":215730,"date":"2025-06-11T06:13:09","date_gmt":"2025-06-11T11:13:09","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2025\/06\/cosmic-rule-of-thumb"},"modified":"2025-06-11T06:13:09","modified_gmt":"2025-06-11T11:13:09","slug":"cosmic-rule-of-thumb","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2025\/06\/cosmic-rule-of-thumb","title":{"rendered":"Cosmic Rule-of-Thumb"},"content":{"rendered":"<p><a class=\"blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/cosmic-rule-of-thumb.jpg\"><\/a><\/p>\n<p>If we chose to shovel matter along a straight line through the observable Universe, what is the average mass of matter per unit area that our shovel will collect? To answer this question, I did a simple calculation before my morning jog at sunrise today.<\/p>\n<p>The answer depends on how far the shovel goes. Projecting all the matter out to the farthest galaxy, <a class=\"\" href=\"https:\/\/arxiv.org\/pdf\/2505.11263\" rel=\"noopener ugc nofollow\" target=\"_blank\">MoM-z14<\/a>, discovered last month by the Webb telescope at a cosmic redshift 14.44 or equivalently 280 million years after the Big Bang, the answer is about 0.5 grams per square centimeter, of order the mass per unit area of a thumb. This establishes the cosmic rule-of-thumb: the observable universe yields on average as much mass per unit area as a thumb.<\/p>\n<p>This mass budget includes mostly dark matter whose nature is unknown. Ordinary matter accounts for only 16% of the total budget or 0.08 grams per square centimeter out to <a class=\"\" href=\"https:\/\/arxiv.org\/pdf\/2505.11263\" rel=\"noopener ugc nofollow\" target=\"_blank\">MoM-z14<\/a>, of order the surface mass density of a fingernail.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>If we chose to shovel matter along a straight line through the observable Universe, what is the average mass of matter per unit area that our shovel will collect? To answer this question, I did a simple calculation before my morning jog at sunrise today. The answer depends on how far the shovel goes. Projecting [\u2026]<\/p>\n","protected":false},"author":427,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33],"tags":[],"class_list":["post-215730","post","type-post","status-publish","format-standard","hentry","category-cosmology"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/215730","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/427"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=215730"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/215730\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=215730"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=215730"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=215730"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}