if you tell me ghosts (not Eliyahu, not shadim, not dybulim, not dream visitations) are in the Gemorah that would be proof enough for me.
The gemarah in kesubos 103a says Rebbe used to come home on Friday night. The gilyon hashas adds that he would be motzi everybody kiddush.
Not that I necessarily believe in anything said here, but is that proof enough?
Between ghosts and “old souls” its starting to get a little bit too new-age in here.