@Slide Rule
Einstein clearly didn't understand anything himself if he believed that to be true.
Well, pete, he didn't say how long it would take, just that a scientist ought to be able to break it down so a six year old could understand. I agree with Einstein on this.
Some of those big scientifical terms are just shorthand for a process, an idea, or a specific thing, but the same concepts can be explained in simpler terms, it just takes a lot longer, and a heck of a lot more typing. So, instead of saying "the lung cells that exchange oxygen with carbon dioxide in the blood", they say Type I Pneumocyte, and type less.
All those ideas can be broken down into simple parts and explained by a scientist who knows their stuff, it's part of understanding the fundamentals. They may be out of practice, but with effort, they could do it (some are better than others).