The expanding universe is a key concept in cosmology, revealing that distances between cosmic structures grow over time. Observations like Hubble's Law and the cosmic microwave background radiation confirm this expansion, which is accelerated by dark energy. This mysterious force accounts for 68% of the universe's total energy, leading to a potential 'Big Freeze' future where the universe cools and star formation ceases. The implications of this expansion are vast, affecting the universe's ultimate fate and our understanding of cosmology.
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The expansion of the universe is a fundamental aspect of its fabric, similar to the stretching of space itself
Hubble's Law
Hubble's Law, which states that galaxies are receding from us at speeds proportional to their distance, provides evidence for the expansion of the universe
Cosmic Microwave Background Radiation
The cooling and stretching of the cosmic microwave background radiation over billions of years also supports the theory of expansion
The Hubble constant estimates that for every megaparsec of distance, the space between galaxies expands by about 70 kilometers per second
Dark energy, a mysterious force that permeates all of space, is responsible for the acceleration of the universe's expansion
Dark Matter
Dark matter makes up approximately 27% of the total energy content of the universe
Ordinary Matter
Ordinary matter, which includes stars, planets, and life, only accounts for about 5% of the universe's energy
Unlike gravity, which weakens with distance, dark energy's repulsive force remains consistent and drives the acceleration of the universe's expansion
Big Crunch
The "Big Crunch" theory suggests that the universe could collapse in on itself if the expansion slows down
Coasting Universe
In a "coasting" universe, the expansion would continue at a steady rate
Heat Death/Big Freeze
The prevailing evidence supports the theory that dark energy will continue to drive an accelerating expansion, resulting in a "Heat Death" or "Big Freeze" scenario where the universe expands forever and grows colder and darker over time
As galaxies move farther apart, their light shifts to longer, redder wavelengths due to the expansion of the universe
The expansion of the universe will eventually lead to a "Big Freeze" where the universe cools and approaches a state of absolute zero
Over time, the raw materials for star formation will become too thinly spread, leading to a decline in new star creation and a gradual fading of the night sky
00
The ______ is expanding, indicating that the space between ______ and other cosmic structures is growing.
universe
galaxies
01
Hubble's 1929 Discovery
Edwin Hubble found galaxies recede faster with distance, forming basis for expansion theory.
02
Hubble's Law Explanation
States universe expands uniformly; galaxy speed proportional to distance from Earth.
