Short answers, pulled from the story.
The universe began as an inconceivably hot and dense point of energy existing for only a fraction of a second before expanding into the vast cosmos we see today. The Planck epoch lasted from time zero to approximately 10 to the negative 43 seconds, during which all four fundamental forces of nature were unified into a single force.
Dark matter accounts for approximately 26.8 percent of the universe's total mass-energy content, while dark energy constitutes about 68.3 percent of the universe. Ordinary matter makes up less than 5 percent of the total mass-energy content, leaving the majority of existence hidden from direct observation.
The age of the universe is estimated to be 13.799 billion years with a margin of error of only 21 million years based on measurements from satellites like the Planck and WMAP probes. The observable universe has a diameter of about 93 billion light-years even though the universe is only 13.8 billion years old because space itself has expanded during the time light has been traveling.
Aristarchus of Samos first proposed a heliocentric model in which the Earth and other planets revolved around the Sun, but this idea was largely ignored until the 16th century. Nicolaus Copernicus revived Aristarchus's perspective in 1543, suggesting that the Sun was at the center of the universe and eventually leading to the Scientific Revolution.
The universe is composed of fundamental particles that interact through four fundamental forces, forming the building blocks of all matter and energy. The Standard Model of particle physics describes 12 fundamental fermions and 4 fundamental bosons that mediate these forces, though the model does not include gravity.
Observations indicate that the universe is flat and expanding, suggesting that the Big Freeze is the most likely outcome where galaxies move so far apart that the universe becomes cold, dark, and lifeless. Another possibility is the Big Rip where the expansion becomes so rapid that it tears apart galaxies, stars, and even atoms themselves.