Quantum fluctuations are temporary changes in the amount of energy at a point in space, as predicted by Heisenberg's uncertainty principle. They occur because particles and antiparticles can spontaneously appear and disappear, even in a perfect vacuum.
In the early universe, quantum fluctuations played a crucial role by seeding the initial density variations in the otherwise homogeneous primordial matter. These tiny perturbations were then amplified by cosmic inflation, leading to the large-scale structures we observe today.
Cosmic inflation is a rapid exponential expansion of space in the early universe. During this period, quantum fluctuations were stretched to macroscopic scales, imprinting tiny variations in density that later evolved into galaxies, clusters, and other cosmic structures.
Yes, the effects of primordial quantum fluctuations can be observed in the Cosmic Microwave Background (CMB) radiation. The tiny temperature variations in the CMB map correspond to the density fluctuations seeded by quantum events in the early universe.
The initial density fluctuations caused by quantum events created regions of slightly higher and lower density in the early universe. Over time, gravity amplified these differences, causing matter to clump together and form galaxies, stars, and other cosmic structures.