I don’t believe we understand the fundamental nature of time, or the universe - we are limited by our bodies, can’t perceive or even think about everything that probably exists. But I don’t distrust the math or research that scientists are doing. In terms of how it is presented to us laypeople I think profit has poisoned the message, it is impossible to be current and knowledgeable in the way you’d need to be to pull apart all that messaging.
If you mean what do you understand but still not believe? I am still not convinced radio is not magic. I understand how it works but what the heck? Magic.