I’m not going into detail with the scientific facts. I’ll just say that a dream is a creation of the brain when we are in another level of consciousness known as sleep. I’m not sure what you mean about “some unknown late people” appearing in a dream. If you mean by late that they’re dead, how would you know that they’re dead if they’re unknown to you? I’ve had people in my dreams who are unknown to me—since I see so many people when I’m out in public who are unknown to me, it would be normal for me to dream about faces which aren’t familiar to me. But how would I know whether any of these people were “late” or dead? I’ve also had dreams about people whom have died. These of course are people whom I have known—my husband, mother, and father. They appear in my dreams because they will live on in my memories forever.