Tag
#cosmology
5 articles
Dark Energy: Why the Universe Speeds Up
Dark energy makes up about 68% of the universe and drives its accelerating expansion — a pressure of space itself, opposite in effect to gravitating dark matter.
The Expanding Universe
Distant galaxies recede faster the farther they are, yet there is no centre and no edge. Run the picture backward and you arrive at a hot dense beginning whose afterglow still fills the sky at 2.725 K.
The Cosmic Distance Ladder
Distance is not something a telescope sees directly. From nearby stars to the edge of the observable universe, every distance is built on a ladder — geometric parallax, then standard candles, then redshift — where each rung borrows its calibration from the one beneath it.
The Cosmic Microwave Background
Point a radio antenna at any patch of empty sky and you pick up the afterglow of the hot dense beginning — a near-perfect 2.725 K blackbody, redshifted from a 3000 K glow, whose faint ripples are the seeds of every galaxy.
Galaxies and Dark Matter
Vera Rubin's flat rotation curves, gravitational lensing, and the Bullet Cluster all point to the same conclusion: galaxies are embedded in vast halos of unseen mass that gravitates but does not shine.