As you know, Professor...
Don't write expert characters as though they're novices
We're all familiar with the old trope of "Tell me again, Professor, how does your machine work?" It's where the author has a convenient sidekick or reporter who doesn't understand some important piece of world-building and asks the question that we, the readers, would have asked if we were there.
It's a very efficient way of giving the reader the information they need to make sense of the story. It can feel awkward and contrived if not done well, but it is, at least, a believable convention. Dr Watson needs Holmes to explain everything to him, as do we, and his questions are perfectly reasonable.
What I find much more irritating is when authors try to use the same technique, but in a conversation between experts. This often takes the form of extra information that the reader may need, but the characters don't.
For example, in a conversation between two computer experts, "I'll contact you via the Skype computer messaging application, which you will be able to access on your cellphone." Ummm... a world-class communications expert doesn't know what Skype is and has to have it explained to them?
Or in a conversation set in the 1950s between two people hunting Nazi treasure: "Adolf Hitler, who, as you know, was leader of the German Reich between 1933 and 1945..." I can't imagine there's anyone in the world who doesn't know who Hitler was. The idea that someone in the fifties, just a few years after the Second World War, would need this explained to them is ludicrous — especially if this is their field of expertise.
Alternatively, it can take the form of the expert taking the role of the not-quite-so-dumb sidekick and asking leading questions. "So, Professor, it looks like you've uprated the quantum oscillator to, what, thirty megacycles?" "Forty, actually. That was the tipping point that allowed me stabilize the temporal fluctuations..." [launches into a long-winded explanation of the machine.]
Scenes like this shatter my suspension of disbelief. When experts talk to each other about their specialist subjects, they're often incomprehensible to anyone else. They don't need to explain the basics to each other — and what they regard as the basics are often very different to what the layman — i.e. the reader — would consider basic information. As soon as they start talking to each other as though they're novices, I stop taking both the story and the writing seriously.
So what's an author to do?
Well, although it has its drawbacks, the sidekick approach works. If you need to explain something to a reader who knows next to nothing about the subject, you might as well explain it to a character who knows nothing about the subject.
However, if your plot won't allow you to have that type of character in the scene, you can explore doing it outside the narrative. Prologues, footnotes or appendices can work extremely well here, for both historical notes and world-building. Create a short aside that breaks the fourth wall and says, hey, reader, I know this may be a little confusing, but this'll help you make sense of it. (And, as you know if you’re a regular, I like footnotes.)
Or else there's a third solution: don't bother explaining. You can take the Doctor Who approach and just give the readers some hand-wavy wibbly-wobbly timey-wimey stuff: you don't need to understand how it works, just enjoy the ride. For real-world information, you can probably assume they’ll look it up. It takes only moments to Google someone or something on my phone if I don't know it already. Most people keep their phone within reach at all times, and they’re used to grabbing it if there’s something they want to know.
And, to be honest, I actually enjoy doing that — many's the time I've ended up spending hours down Wikipedia rabbit holes while reading a novel or watching TV. There’s a fantastic moment at the end of Apple Cider Vinegar, the Netflix show about wellness scammer Belle Gibson. At the end of the show, they start to roll the usual epilogue about what happened to her after the end of the story. But then the main character pops back on-screen, looks right at the audience, and says, “you know what, you can just Google it.” And of course, I already had — just like many others. TV is now designed around people using their phones as a “second screen” — so why not books?
Any of these approaches can work well. Just, please, don't have your experts talking to each other like newbies.