"interstellar medium particles"
https://www.nasa.gov/feature/goddard/2020/new-evidence-our-neighborhood-in-space-is-stuffed-with-hydrogen
"The aether exists and it is the medium for propagating light and other longitudinal and transverse (electromagnetic) waves across the universe. It is the fabric of our universe, consisting of tiny granules that transfer energy in the form of waves. Its structure and properties were worked out in the section on spacetime."
https://energywavetheory.com/explanations/aether/
"ionized gas having a proton and electron density of about 3 - 10 particles per cubic centimeter, with an average flow velocity of approximately 400 km/s."
https://umbra.nascom.nasa.gov/spartan/the_solar_wind.html
"Each photon contains a certain amount of energy. The different types of radiation are defined by the the amount of energy found in the photons."
https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html
"If the frequency of the photon is high, its energy will also be high. Hence, we can say if the wavelength of the photon is longer, the energy is lower."
https://byjus.com/physics/photon-energy
"photons have similar properties to electromagnetic waves. Each photon has a wavelength and a frequency."
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Quantum_Mechanics/02._Fundamental_Concepts_of_Quantum_Mechanics/Photons