Albert Einstein's discarded 'cosmological constant' returned as a central component of the modern LCDM model of the universe.
Key facts
- •Einstein introduced the cosmological constant in 1917 to keep his universe model static.
- •Edwin Hubble later discovered the universe is expanding, leading Einstein to label his constant a 'greatest blunder'.
- •In 1998, astronomers found that cosmic expansion is accelerating rather than slowing down.
- •The cosmological constant was revived as dark energy to explain this acceleration.
- •The current LCDM model integrates Lambda and cold dark matter to describe cosmic evolution.
In 1917, Albert Einstein applied his general theory of relativity to cosmology, finding that his equations suggested a dynamic rather than static universe. To maintain a stable cosmos, he introduced a 'cosmological constant'—represented by the Greek letter Lambda—which he later famously dismissed as his greatest blunder. However, 1998 observations revealed that the universe's expansion is accelerating, leading scientists to revive the constant as the leading explanation for this phenomenon.
From Static Universe to Expansion
Einstein initially believed the universe was static, a view held by many at the time. By adding the cosmological constant to his equations, he created a gravitational influence built into spacetime that could counteract the pull of matter. This allowed for a stable universe model. Shortly thereafter, Edwin Hubble discovered that the universe is actually expanding, and theorists like Alexander Friedmann used Einstein’s equations to build the foundation for the Big Bang theory.
The Discovery of Accelerated Expansion
In 1998, astronomers studying the expansion of the universe expected to find that gravity from matter was slowing it down. Instead, they discovered that the expansion was accelerating. This finding required a new explanation for what was pushing the cosmos apart. Researchers returned to Einstein’s cosmological constant, which acts as a background effect producing cosmic repulsion.
The LCDM Model
The discovery of accelerating expansion necessitated a shift in the Standard Model of Cosmology, leading to the current LCDM model. 'Lambda' refers to the cosmological constant, now identified as dark energy, while 'CDM' stands for cold dark matter. This model is now one of the most extensively tested theories in science, accounting for observations ranging from background radiation to the growth of galaxies.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by ScienceDaily.
