↩ 🔵 🔵 🔵 ❪✺❫ Physical Concepts ○ ❪✺_₀❫ Sub Portals ○ ❪✺_❫ Astronomical Subs ○ ❪✺_❫ Electromagnetic Subs ○ ❪✺_❫ Mechanical Subs ○ ❪✺_❫ Thermodynamic Subs ○ ❪✺_ₛₛ❫ Physical Subsets ○ Blackbody Radiation ○ Electromagnetic Radiation ○ Inertial Frame of Reference ○ Soliton ○꠹ Spacetime ○ Synchrotron Radiation ○ Thermal Radiation ○