Recent advances in silicon photonic led to the demonstration of unique high quality structures that support modes in completely different spectral domains. For example, suspended ultra high Q structures can confine both optical modes in the NIR and Vibrational modes in the RF, and specially designed structures can act as traveling waves for both optical modes in the NIR and electrical modes in the microwave. The strong interaction between these different modes across the electromagnetic spectrum can enable novel fundamental phenomena. We have recently demonstrated that strong interaction between light and optical phonons in suspended structures can lead to near-field radiative cooling of a thermally isolated nanostructure. We have also demonstrated that strong interaction between light and acoustic phonons can lead to synchronization of mechanical structures, and between light and electrical fields can lead to optical non-reciprocity.