Do the dead know what happens in the land of the living?
The Talmud discusses this question at length in Berachot 18a-19a (starts with "R. Hiyya and R. Jonathan were once walking about in a cemetery").
Aside from interpretations of biblical verses, much of the evidence comprises anecdotes about the exploits of spirits in cemeteries. Read them and be spooked.
So, how are we moderns to relate to such passages? Are we required to believe them since they appear in the Gemara? Apparently the sages did, to the extent of determining halacha on their basis.
May we dismiss them as folk tales? On what basis would we do that? Just because they sound fantastical? They aren't more unbelievable than a host of biblical passages which Orthodox Jews certainly do believe (the flood, the splitting of the sea, the sun standing still, to name a few).
From a scientific perspective, science can neither prove nor disprove such tales. Just because we have no confirmed evidence of spirit communications is not proof that they do not exist. The fact that many modern westerners cringe at such stories is not evidence that they are false.
The issues at stake here are similar to those in the Nosson Slifkin controversy, though one step removed. Unlike the age of the earth or animal anatomy, science has no decisive position on ghosts and spirits. A lack of evidence does not constitute proof, as the Talmudic maxim goes. If we reject ghosts, we do so based on our own instincts and experiences. No scientific methodology can decide the question.
On the question of spirits, we are not forced into a choice between science and Torah. So why do we find it so difficult?