Cosmic Distance Ladder on Instagram: "When Einstein developed his general theory of relativity, he noticed that his equations predicted the universe could expand and then contract, or expand forever; but without additional counteracting laws of physics, it could not stay at a steady size indefinitely. In order to make his theory better fit the prevailing “steady state” model of the universe of his time, Einstein added a term to his equations, involving an unknown “cosmological constant” Λ (Lambda), that caused the vacuum of space itself to inherently expand and counteract the contracting force of gravity. Although evidence from the 1930s onwards favored an expanding universe (the “Big Bang” model) and Einstein removed this constant from his equations, reportedly calling it his “biggest blunder”, we now view this constant as one of the simplest forms of “dark energy”. But in the 1990s, two large research teams, headed by Saul Perlmitter, and Adam Riess and Brian P. Schmidt, respectively, precisely measured the distance from the Earth of supernovae designated type Ia (“one-A”). Both projects independently discovered that the expansion of the universe was not slowing (as they expected) but accelerating over time. The simplest way to explain these facts was to reinstate a (small) cosmological constant Λ, leading to the standard “Λ-CDM” model of the universe today (the CDM stands for “cold dark matter”). Perlmutter, Riess, and Schmidt received the 2011 Nobel Prize in Physics for the discovery. Now, new analysis from an ongoing survey using the Dark Energy Spectroscopic Instrument (DESI) suggests this acceleration is itself fluctuating in time. It seems dark energy, usually treated as synonymous with the “cosmological constant” is not actually constant after all, but potentially evolving. As the study confirms the existence of the mysterious phenomenon of dark energy, it simultaneously shows that there is much about it that we still don’t understand. The last rung in the Cosmic Distance Ladder is “How big is our universe?”. For now, each new result seems to suggest it is growing bigger than any previous model believed it could be. #DistanceLadder #astronomy #DarkEnergy #astrophysics #cosmology #DESI"

19 likes, 1 comments - cosmic_distance_ladder on April 9, 2025: "When Einstein developed his general theory of relativity, he noticed that his equations predicted the universe could expand and then contract, or expand forever; but without additional counteracting laws of physics, it could not stay at a steady size indefinitely. In order to make his theory better fit the prevailing “steady state” model of the universe of his time, Einstein added a term to his equations, involving an unknown “cosmological constant” Λ (Lambda), that caused the vacuum of space itself to inherently expand and counteract the contracting force of gravity. Although evidence from the 1930s onwards favored an expanding universe (the “Big Bang” model) and Einstein removed this constant from his equations, reportedly calling it his “biggest blunder”, we now view this constant as one of the simplest forms of “dark energy”. But in the 1990s, two large research teams, headed by Saul Perlmitter, and Adam Riess and Brian P. Schmidt, respectively, precisely measured the distance from the Earth of supernovae designated type Ia (“one-A”). Both projects independently discovered that the expansion of the universe was not slowing (as they expected) but accelerating over time. The simplest way to explain these facts was to reinstate a (small) cosmological constant Λ, leading to the standard “Λ-CDM” model of the universe today (the CDM stands for “cold dark matter”). Perlmutter, Riess, and Schmidt received the 2011 Nobel Prize in Physics for the discovery. Now, new analysis from an ongoing survey using the Dark Energy Spectroscopic Instrument (DESI) suggests this acceleration is itself fluctuating in time. It seems dark energy, usually treated as synonymous with the “cosmological constant” is not actually constant after all, but potentially evolving. As the study confirms the existence of the mysterious phenomenon of dark energy, it simultaneously shows that there is much about it that we still don’t understand. The last rung in the Cosmic Distance Ladder is “How big is our universe?”. For now, each new result seems to suggest it is growing bigger than any previous model believed it could be. #DistanceLadder #astronomy #DarkEnergy #astrophysics #cosmology #DESI".

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