Light travels at 299,792,458 meters per second in vacuum. Einstein's special relativity theory in 1905 explained light's nature. Light is both a wave and particle, with different propagation through media
Cosmology combines astronomy and physics to understand the universe as a unified whole. Observable universe is Earth-centered bubble, while universe is possibly infinite. Stars appear densely packed in Milky Way due to their vast distances
Einstein derived special relativity in 1905 from two fundamental principles. Lorentz and Poincaré derived Lorentz transformation from Maxwell's equations. Alternative derivations proposed by Ignatowski, Frank, and Rothe
Zika virus spreads worldwide through mosquitoes and causes birth defects. Sneezing is a natural reflex triggered by allergens and viruses. Elephantiasis is a parasitic disease affecting millions worldwide. Tetanus is a serious bacterial infection with 10-20% fatality rate
hc combines Planck's constant (h) and speed of light in vacuum (c). Expressed in units of eVm or Jm. Value in Joules: hc = 1.98644568×10^-25 J.m. Value in MKS units: hc = 1.23984193×10^-6 eV.m
Speed of light is the universe's maximum speed. In vacuum, light travels at 299,792,458 m/s or 670,616,629 mph. Light travels faster in air than in water due to refraction