1. The problem statement, all variables and given/known data Consider a real free scalar field Φ with mass m. Evaluate the following time-ordered product of field operators using Wick's theorem: ∫d^4x <0| T(Φ(x1)Φ(x2)Φ(x3)Φ(x4)(Φ(x))^4) |0> (T denotes time ordering) 2. Relevant equations Wick's theorem: T((Φ(x1)....Φ(xn)) = : (Φ(x1)....Φ(xn)) + all possible contractions : ( : ... : denotes normal ordered product) 3. The attempt at a solution I'm really confused here. I've seen examples of using Wick's theorem to evaluate products like T(Φ(x1)Φ(x2)Φ(x3)Φ(x4)) , i.e. field evaluated at fixed values of x only ... but here, there is another term that's integrated over all possible x values. And I have no idea how to deal with that - I've never seen anything like that done in the lectures I've had on this stuff. I know contractions of the form "contraction(Φ(x1)Φ(x2))" give Feynman propagators. But that's all I've got... I'm really bad at this stuff, so if someone can help explain / help me work through this from absolute basics (i.e. assuming I know pretty much nothing), that would be really appreciated!