This is something that has really been bugging me lately. There was a study from over twenty years ago that proposed that electromagnetic radiation might have been able to pass from one end of the universe to another in the early universe, furnishing an explanation for the homogeneity of the universe today. However, I also know that it is a common belief that a given electromagnetic wave cannot traverse an aperture with a width smaller than its wavelength. However, I have found many physics textbooks and university webpages that contradict this, leading me to think this may just be a common misconception or an old wives' tale. But anyway, if this was true, then the physicists who conducted that study would surely have been aware of it. Surely, a Planckian-sized wormhole's mouth diameter would be far smaller than the wavelength of any travelling electromagnetic wave. So does this mean that this supposed rule, which I think might be a misconception, is true, but it does not apply to wormholes, or does it mean that this supposed rule is untrue? Thank You.