In a vacuum, electromagnetic waves can propagate without any medium and do not require oscillation of energies to achieve higher frequencies. The frequency of an electromagnetic wave is determined by the rate at which its electric and magnetic fields oscillate. In a vacuum, these oscillations can occur at any frequency within the electromagnetic spectrum, ranging from extremely low frequencies (ELF) to extremely high frequencies (EHF) and beyond.
The electromagnetic spectrum encompasses a wide range of frequencies, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each frequency range corresponds to different energy levels and characteristics of the electromagnetic waves.
It's important to note that the concept of "energy oscillation" is not directly related to achieving higher frequencies in the context of electromagnetic waves. The frequency of an electromagnetic wave is determined by the source or the physical process that produces it, such as an oscillating electric charge or a transition between energy levels in an atom. In a vacuum, electromagnetic waves can freely propagate at different frequencies without the need for energy oscillation.