When someone asked me how it was like relearning something I had studied a few years ago. I said:
It hasn’t changed since the last time I saw it
I said it under slight derision. I keep learning but at least the old ideas haven’t changed so its easy to remember. It’s not as if the math and formalism will run off and change since I looked at it lasst.
Looking back thought, that DOES happen!
In active research, things change and even though we may read the same paragraph, it can look drastically different a few years later. Maybe the discoveries within the field have made colored past experiments as bad or good or false or indicative of a then-future, now-past truth. Or maybe our perspectives, priorities, or attention to detail have changed.
The things we read now will not read the same down the line. In truth, it is quite surprising that we make any progress at all. Thank god for the scientific method.