Summary
Highlights
The universe began as a fireball smaller than an atom, hotter than the sun's core, exploding from a single point. This event, known as the Big Bang, marked the beginning of time and laid the blueprint for the entire cosmos. For centuries, the universe was considered static, but Edwin Hubble's 1929 discovery of red-shifted light from distant galaxies proved the universe is expanding, providing the first evidence of a beginning.
In the first Planck time (10^-43 seconds) after the Big Bang, the four fundamental forces of nature – gravity, electromagnetism, and the strong and weak nuclear forces – began to form. Initially unified as a 'Super Force,' they gradually separated as the universe expanded and cooled. These forces are crucial for the existence of stars, planets, and everything else in the universe.
A few Planck times after creation, the universe underwent rapid expansion called 'inflation,' growing from atomic scale to the size of a baseball almost instantaneously. Evidence for this expansion, and how galaxies formed, comes from the Cosmic Microwave Background (CMB) radiation. Satellites like WMAP observed tiny temperature variations in the CMB, which represent the initial 'lumps' from which stars and galaxies eventually coalesced under gravity over billions of years.
According to Einstein's E=mc² equation, the immense energy of the Big Bang converted into particles of matter as the universe expanded and cooled. Early matter existed as a super-hot 'quark-gluon liquid,' not a gas, as recreated in particle accelerators like Brookhaven's RHIC. In this tumultuous environment, both matter and its counterpart, antimatter, were produced in nearly equal amounts, leading to an intense battle of annihilation. A slight imbalance in favor of matter, though still a mystery, allowed the universe to ultimately be filled with the matter we see today.
A key missing piece in understanding the first second is what gives matter its mass. Peter Higgs' 1964 theory proposed an invisible 'Higgs field' pervading the universe, which particles interact with to gain mass. The more interaction, the more mass. The Large Hadron Collider (LHC) in Geneva, a massive particle accelerator, was built to recreate Big Bang conditions and search for the Higgs boson, the particle associated with this field. Its discovery, or lack thereof, would profoundly impact our understanding of the universe.
By the end of the first second, the universe was about a thousand times the size of our solar system, filled with matter particles. It had cooled enough for quarks to combine into protons and neutrons, the building blocks of atomic nuclei. This fundamental moment set the stage for all cosmic history, leading to the formation of the first atomic nuclei, then atoms, stars, galaxies, and eventually, Earth and human life, capable of pondering its own origins.