According to Osho, it feels difficult because science and meditation are polar opposites: science is concentrated, effortful mind; meditation is relaxed, no-pointed let-go. Philosophical synthesis destroys both. Instead, see their innate complementarity - like work and rest, day and night - and consciously move between them. With maturity, each pole nourishes the other, allowing a scientist who is also meditative.
Because science needs tight focusing and meditation needs total relaxing—like working hard and then sleeping—you can’t do both at once, so you switch between them.