{"id":4771,"date":"2025-04-15T22:09:17","date_gmt":"2025-04-15T21:09:17","guid":{"rendered":"https:\/\/savedblog.com\/?p=4771"},"modified":"2025-04-16T15:50:52","modified_gmt":"2025-04-16T14:50:52","slug":"hubble-tension","status":"publish","type":"post","link":"https:\/\/savedblog.com\/?p=4771","title":{"rendered":"Hubble Tension."},"content":{"rendered":"\n

Three scientists\u2014Papaia, Banani, and Ravioli\u2014and their assistant Igor work at the NASAL observatory. They come across some interesting books and start getting into creationism. But their bosses don\u2019t like this new interest and send them to take a psychological test, which they must pass to keep their jobs. But Papaia has forgotten where the psychologist\u2019s office is. So they ask a janitor, who, acting a bit strange, points them to a room. Inside the room they were sent to, instead of a psychologist, they find a nurse wearing gloves and a mask, who starts asking them strange questions.<\/em><\/p>\n\n\n\n

We are in the waiting room of the infirmary where Papaia and Banani are waiting for Ravioli, who is taking \u201cthe\u201d test.<\/p>\n\n\n\n

Banani: Are you sure, Papaia, that you measured Hubble\u2019s constant correctly?<\/p>\n\n\n\n

Papaia: I\u2019m 100% sure! We repeated the measurements many times in every possible way. You were there too, don\u2019t you remember?<\/p>\n\n\n\n

Banani: Yes, but in the end, what\u2019s the problem if we get two slightly different values?<\/p>\n\n\n\n

Papaia: You see, Banani, we measured the same constant in two different ways. The first with redshift, the second with the CMB background radiation. If this constant is truly constant, the values should be very close to each other.<\/p>\n\n\n\n

Banani: I still don\u2019t get it.<\/p>\n\n\n\n

Papaia: Let me give you an example. Imagine measuring Earth\u2019s gravitational acceleration, which we call \u201cg.\u201d<\/p>\n\n\n\n

Banani: You mean the force that keeps us grounded and makes everything fall to the ground?<\/p>\n\n\n\n

Papaia: More or less\u2026 \u201cg\u201d represents the value of the acceleration caused by that force.<\/p>\n\n\n\n

Banani: Pretty much the same thing, right?<\/p>\n\n\n\n

Papaia: Not exactly: to calculate the force, we also need mass to do the calculation: mass times acceleration. But in this case, we\u2019re just measuring the acceleration \u201cg.\u201d<\/p>\n\n\n\n

Banani: I think I get it.<\/p>\n\n\n\n

Papaia: And the value of \u201cg\u201d on Earth\u2019s surface is constant, meaning it doesn\u2019t change over time, and it\u2019s about 9.81 meters per second squared.<\/p>\n\n\n\n

Banani: Yeah, I think I\u2019ve heard that number before, maybe at school.<\/p>\n\n\n\n

Papaia: Essentially, when anything is in free fall, its speed increases by about 9.81 meters per second every second.<\/p>\n\n\n\n

Banani: I think I\u2019m following you.<\/p>\n\n\n\n

Papaia: Great! So, we can measure this value in various ways. For example, using the oscillations of a pendulum or a ball rolling down an inclined plane. These are two independent methods to measure the same thing, \u201cg.\u201d<\/p>\n\n\n\n

Banani: I see. We\u2019re using two measurement methods to measure the same quantity.<\/p>\n\n\n\n

Papaia: Very good, I see you\u2019re getting it now. So, both with the pendulum and the inclined plane, we should, and do, always get the same result: 9.81 meters per second squared.<\/p>\n\n\n\n

Banani: But that\u2019s not what happens with Hubble\u2019s constant?<\/p>\n\n\n\n

Papaia: Exactly! That\u2019s the issue. When we measure Hubble\u2019s constant with redshift, we get 67.4 km\/s\/Mpc (kilometers per second per megaparsec). But when we measure it with the CMB, we get 73 km\/s\/Mpc.<\/p>\n\n\n\n

Banani: But those are different values!<\/p>\n\n\n\n

Papaia: Exactly, and we have an error greater than 8%!<\/p>\n\n\n\n

Banani: Couldn\u2019t it be the instruments, as the boss says?<\/p>\n\n\n\n

Papaia: No, Banani! Let me explain. According to the theoretical model, we expect a value of 67.5 km\/s\/Mpc. This value is perfectly confirmed by the most advanced spectroscopes, which have a maximum error margin of 1%. But when we measure the same constant with the CMB method, using advanced instruments like the Hubble and Webb space telescopes, we get a value of 73 km\/s\/Mpc, despite their 1% error margin.<\/p>\n\n\n\n

Banani: Surely 8 percent is off the charts!<\/p>\n\n\n\n

Papaia: That\u2019s why something doesn\u2019t add up in the Big Bang model.<\/p>\n\n\n\n

Igor: Papaia showed us that there are serious doubts about the Big Bang model. I agree, the Big Bang doesn\u2019t add up! Just like this situation doesn\u2019t add up. In fact, we have found a nurse… as a psychologist!<\/p>\n\n\n\n

\ud83e\udd23\ud83e\udd23\ud83e\udd23<\/p>\n\n\n\n

\n
Previous<\/a><\/div>\n\n\n\n
Next<\/a><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Three scientists\u2014Papaia, Banani, and Ravioli\u2014and their assistant Igor work at the NASAL observatory. They come across some interesting books and start getting into creationism. But their bosses don\u2019t like this new interest and send them to take a psychological test, which they must pass to keep their jobs. But Papaia has forgotten where the psychologist\u2019s … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-4771","post","type-post","status-publish","format-standard","hentry","category-episode"],"_links":{"self":[{"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4771","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/savedblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4771"}],"version-history":[{"count":4,"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4771\/revisions"}],"predecessor-version":[{"id":4872,"href":"https:\/\/savedblog.com\/index.php?rest_route=\/wp\/v2\/posts\/4771\/revisions\/4872"}],"wp:attachment":[{"href":"https:\/\/savedblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4771"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/savedblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4771"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/savedblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4771"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}