Chapter 1
The fifth element of the heavens
Chapter 2
Alchemy and the elixir of life
Chapter 3
The cosmic tug of war
Chapter 4
The fate of the universe
YOUR GOAL
Master of Unmasking the fifth element
Ch 3 · The cosmic tug of war
007skaty The Cosmic Tug of War
Gravity pulls the matter in, but quintessence pushes space apart.
007skaty Einstein's 1917 cosmological constant represents a fixed cosmic energy, but quintessence models allow dark energy to change as
BETA
007skaty Tug the cosmic rope to discover how gravity and dark energy shape the universe.
Fun Fact
Dark energy dominance: The repulsive force of cosmic quintessence remained completely hidden, tracking matter and radiation, until it suddenly took over five billion years ago.
Glossary
dark energy (noun)
A hypothetical form of energy that exerts a negative pressure, causing the universe's expansion to accelerate. This repulsive force overcame gravity's attractive pull about five billion years ago to dominate cosmic expansion.
A hypothetical form of energy that exerts a negative pressure, causing the universe's expansion to accelerate. This repulsive force overcame gravity's attractive pull about five billion years ago to dominate cosmic expansion.
Quiz
Which cosmic markers did astronomers use in 1998 to measure the acceleration of the universe?
Quiz
In what year did astronomers discover that the expansion of the universe is accelerating?
Quiz
What percentage of the universe is estimated to consist of mysterious dark energy?
Quiz
Who coined the modern term 'quintessence' for dynamic dark energy in a landmark 1998 paper?
Quiz
What is the name of the quintessence behavior where its density follows radiation and matter for billions of years?
Quiz
Which two physicists proposed the first mathematical model of quintessence dark energy in 1988?