MY ADVENTURE WITH ENTROPY
Entropy: a measure of uncertainty or randomness; lack of order or predictability; gradual decline into disorder.
COSMIC CONUNDRUM
➤ Clara Moskowitz, Scientific American, February 2021
The Cosmological Constant Is Physics’ Most Embarrassing Problem
The cosmological constant has a checkered history. “It was what you could call a nonsolution to a nonproblem,” says physicist Rafael Sorkin of the Perimeter Institute for Theoretical Physics in Ontario. Albert Einstein first invented it in 1917 as a mathematical kludge to force his general relativity field equations to predict a static universe, as he and most scientists then believed the cosmos to be. But in 1929 astronomer Edwin Hubble measured the speeds of many galaxies and found, to his surprise, that they are all moving away from us, in fact, the farther away the galaxy, the faster it was going. His measurements showed that space is expanding everywhere, and no matter where you look, it will seem as if all galaxies are receding because the distance between everything is constantly growing.
THREE PIECES OF THE PUZZLE
The cosmological constant problem is a major mystery in physics: the value of the constant, part of Albert Einstein’s general relativity equations, seems to be much, much smaller than theories predict it should be. At the heart of this puzzle are three intertwined concepts—vacuum energy (the energy in empty space), dark energy (the cause of the accelerating universe) and the constant itself.
A term, represented by the Greek letter
LAMBDA
that Einstein included in his general relativity equations (below) that describe how matter and energy bend spacetime
VACUM ENERGY
The energy in empty space, made of “virtual particles”—pairs of particles and antiparticles that constantly appear and disappear
DARK ENERGY
The force causing the expansion of the universe to accelerate
- describes the curvature of spacetime
- describes the structure of spacetime
- (lambda), the cosmological constant, can
describe a repulsive force throughout space
- the gravitational constant
- describes the energy and momentum
of matter and radiation
- the speed of light
✤ Origin
✤ Why Entropy?
✤ Entropy Arguments
✤ Survival of the Friendliest
✤ Recent Therapies
✤ Intergalactic Polemic
✤ Bibliography
