That is the simple explanation. In more technical terms diffraction is when the airy disk is larger than circle of confusion and there is a formula to to determine what it will be with each current lenses. Aperture is the the focal length divided by physical size of the opening. 1 stop is double the light. Because the area is╥r2, double the light is the square root of 2 for the aperture or 1.4.
This is using air and common glass. They are currently making super materials that affect the movement of photons. The government has some telescopes that use one of these super materials instead of air in telescopes. It currently has a 4 to 1 ratio so an 80" telescope is 20" long. Which when it gets to civilian use will allow long tele lenses to be sorter and lighter. This is today. In the labs they was working on super materials that will affect the dispersion of photons (cause of diffraction). Once it gets here, the the diffraction at small lens openings will be less.