Let's say I'm currently researching Machine Tools. It's well in progress, at 1971/3119 with 3 turn to go. I sudenly change my mind and decide it's important to start researching Communism right no. What happens to the 1971 "bulbs"

I have accrued so far toward Machine Tools ? Will they be still there when I come back to researching Machine Tools again, or will I start again from zero ?
Well, I suppose I could take some notes and experiment. Or the answer may already be there somewhere, but I haven't found it so far. Anyway, I thought it would be more congenial to ask you nice

fellows