Well, yes, radiation flows through empty space, the others do not which is why a vacuum bottle works but not perfectly :)
matter
The unscrambled word is "matter." Both convection and conduction require the presence of matter to transfer thermal energy. Convection involves the transfer of heat through the movement of fluids (liquids or gases), while conduction involves the transfer of heat through direct contact between particles of matter. In both cases, without the presence of matter, there would be no medium to transfer the thermal energy.
