• radar, 1, 2
• Radford, Tim, 1
• radiation-dominated era, 1, 2
• radio astronomy: invention, 1
• radio galaxies, 1
• radio telescopes, 1
• radio waves, 1, 2, 3
  • see also microwaves
• radioactivity, 1, 2
• radiometers, 1
• red dwarfs, 1
• red giants, 1
• red shift 1, 2
• relativity, theory of, 1, 2
• Relict I, 1
• rest energy, 1
• Richards, Paul, 1, 2, 3, 4
• Rickson, Jerry, 1
• Roll, Peter, 1, 2, 3, 4, 5, 6
• room temperature, 1
• Rutherford, Ernest, 1
• Ryle, Martin, 1