in reply to Re^5: Organizational Culture (Part VII): Science
in thread Organizational Culture (Part VII): Science

> many felt that "bending space and time" was obviously too absurd to survive further scrutiny

Agreed. Einstein similarly felt it was obviously too absurd for nature to allow a black hole to exist - despite it being predicted by his own equations! :)

The first exact solution of the Einstein field equations was provided, not by Einstein, but Karl Schwarzschild, a German soldier stuck in a foxhole on the Russian front during WW1. Schwarzchild further calculated the Schwarzschild radius, defining the event horizon of a Schwarzschild black hole. Calculating the first exact solution of the Einstein field equations proved more alluring than the mundane chore of computing artillery trajectories it seems. Tragically, Schwarzschild did not survive the war.

Sadly, Einstein mocked Belgian Catholic priest Georges Lemaitre's "hypothesis of the primeval atom" (aka "Cosmic Egg" aka Big Bang theory) with the cutting quote "Your calculations are correct, but your grasp of physics is abominable" ... missing a golden opportunity to scoop Edwin Hubble by predicting an expanding universe. Lemaitre took this opportunity by publishing his expanding universe theory, despite Einstein's objections, and so was (belatedly) recognized for predicting an expanding universe two years before Hubble, with Hubble's Law now also known as the Hubble-Lemaitre Law (not the Hubble-Einstein Law).

Wait, there's more tragedy! To fit the then accepted model of a steady state universe, Einstein added the Cosmological constant to his field equations. From Dark energy (wikipedia):

The cosmological constant was first proposed by Einstein as a mechanism to obtain a solution of the gravitational field equation that would lead to a static universe, effectively using dark energy to balance gravity. Einstein gave the cosmological constant the symbol capital lambda. Einstein stated that the cosmological constant required that 'empty space takes the role of gravitating negative masses which are distributed all over the interstellar space'.

The mechanism was an example of fine-tuning, and it was later realized that Einstein's static universe would not be stable: local inhomogeneities would ultimately lead to either the runaway expansion or contraction of the universe.

After Einstein admitted his blunder by removing the cosmological constant (and deeply regretting adding it in the first place), others later reinstated it as a perfect way to describe the mysterious new Dark energy!! You can't write this stuff. :)

Update Physics Today: I heard Einstein say to Gamow about the cosmological constant, "That was my biggest blunder of my life" -- John Archibald Wheeler

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Re^7: Organizational Culture (Part VII): Science
by jdporter (Paladin) on Sep 15, 2021 at 13:31 UTC
    a perfect way to describe the mysterious new Dark energy

    I wouldn't put it that way, and I think you have it backwards. The cosmological constant is a mathematical element added to make the math describe the observed universe. Dark energy is a purely theoretical physical explanation for the cosmological constant.

[reply]

      I'm a bit rusty on all this stuff. From Dark energy (wikipedia):

      The "cosmological constant" is a constant term that can be added to Einstein's field equation of general relativity. If considered as a "source term" in the field equation, it can be viewed as equivalent to the mass of empty space (which conceptually could be either positive or negative), or "vacuum energy".

      The simplest explanation for dark energy is that it is an intrinsic, fundamental energy of space. This is the cosmological constant, usually represented by the Greek letter Λ (Lambda, hence Lambda-CDM model). Since energy and mass are related according to the equation E = mc2, Einstein's theory of general relativity predicts that this energy will have a gravitational effect. It is sometimes called a vacuum energy because it is the energy density of empty space - the vacuum.

      There is a minor problem with this though: the discrepancy between theoretical calculation and observed value is 120 orders of magnitude!!! ... making it a leading candidate for "the largest discrepancy between theory and experiment in all of science". :)

      On a more positive note, the precision of narrowing down the Age of the universe (via the Lambda-CDM model) to 13.772±0.040 billion years blows my mind.

[reply]

        No, you're getting confused: vacuum energy and dark energy are not the same thing. The latter is purely theoretical, hypothesized as an explanation of the cosmological constant; it has never been observed, and we have no idea what it is - if it exists - so there's no way for there to be a discrepancy. Or maybe I'm confused. Whatever. ;-)

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