I believe that the "veil" between this world and the next thins or lifts when a person is close to death. And loved ones can be seen and heard by the dying one, waiting to welcome them after they pass. I am very spiritual and it is something that I believe, but medicine will find some way to write it off as some psycological condition because they can't explain it, and there is no evidence of it.
But science and medicine can only go so far in understanding the works of the world because they close out the spiritual possibilities behind the causes of life. They know what black holes are, but can't really figure them out. They understand the Big Bang, but fail to know why it happened. They know a baby is created in it's mom, but fail to explain the true force behind what is the builder of the form. They know humans come from monkeys, but can't explain what gives us the intelligent consciousness, and why monkeys today are not developing that. They know that music, colors, and needles poked in certain places can bring about healing, but don't understand why.
Humanity is in it's infancy and really has only begun to understand things in the past 100 years or so. Our technology is fairly new, but it cannot answer all the questions. There is some driving force behind nature, causes and effects, death, and birth, and until we open up our minds to possibilities other than the physical, we will not be able to comprehend very far. We will not see the whole picture, just part of it.