Pacifism is very powerful if you set it up properly to generate GP quickly. usually you will need a few cities with your state religion, grow them up, and then start running as many specialists with Caste System as you can (even starving) in all the cities around the same time. Combining with a Golden Age gives the best effect. Sorta dependent on getting a religion and requires a bit of oversight to make sure it spreads to the right cities and timing the Golden Age. But it's pretty easy to farm 3-5 scientists this way PHI or not.
You can also focus on one city for the most part; pick a spot with as much food as possible (3+ food resources), build the NE there, make sure the religion you want to use for Pacifism is spread there. Grow it to happy cap and run as many specialists as it can without starving; over time it will generate several GPs. You can still combine it with a Golden Age, where you will starve it mercilessly like with the multiple city approach.
The bog standard way to get scientists for Lib path or Astro path is just run scientists with Libraries, Pacifism/GA or not. Get a few cities with sufficient food surplus (+4 or better at size 3 or 4) set up with libraries and running a pair of scientists. Don't take them off until that cities generates its GS, afterwards they can repurpose the pop and do something else. The key to this is doing it as EARLY as possible and starting scientist production at around the same time as much as possible in all the cities. If you run a pair of scientists in each city starting on the same turn, you'll gain a GS every 17 turns for each city that starts at the same time
i.e.
4 cities
all cities start running scientists on T90
city1: T107 - city goes back to growing/whipping and no longer running 2 scientists
city 2: T124
city 3: T141
city 4: T158
And then you would typically bulb Philo>Education (twice)>Lib or Machinery>Optics>Astro (twice). You can cut out one of the bulbs if you only get 3 scientists in time, try to skate by with only 2, etc.
There's a limit because it depends a lot on how quickly you can start all cities together based on REX and Writing date. but getting 2-4 scientists to use on the Lib or Astro path in time to still be useful should be doable if your land is conducive. It also possible to just cycle scientists between less (like a pair of) cities, but they can never stop running scientists for that to work.
