People tend to interpret what they see based on their background: A Hindu describes a Hindu god, an atheist doesn't see a Hindu god or a Christian god, but some being. Different cultures see the same thing, but their interpretation depends on what they believe.

Wired: What can we learn from the fact that people report seeing the same thing?

Parnia: At the very least, it tells us that there's this unique experience that humans have when they go through death. It's universal. It's described by children as young as three. And it tells us that we should not be afraid of death.

Wired: How do we know after-death experiences happen when people think they do? Maybe people misremember thoughts from just before death, or just after regaining consciousness.

Parnia: That's a very important question. Do these memories occur when a person is truly flatlined and had no brain activity, as science suggests? Or when they're beginning to wake up, but are still unconscious?

The point that goes against the experiences happening afterwards, or before the brain shut down, is that many people describe very specific details of what happened to them during cardiac arrest. They describe conversations people had, clothes people wore, events that went on 10 or 20 minutes into resuscitation. That is not compatible with brain activity.

It may be that some people receive better-quality resuscitation, and that – though there's no evidence to support it – they did have brain activity. Or it could indicate that human consciousness, the psyche, the soul, the self, continued to function.

Wired: Couldn't the experiences just reflect some extremely subtle type of brain activity?

Parnia: When you die, there's no blood flow going into your brain. If it goes below a certain level, you can't have electrical activity. It takes a lot of imagination to think there's somehow a hidden area of your brain that comes into action when everything else isn't working.

These observations raise a question about our current concept of how brain and mind interact. The historical idea is that electrochemical processes in the brain lead to consciousness. That may no longer be correct, because we can demonstrate that those processes don't go on after death.

There may be something in the brain we haven't discovered that accounts for consciousness, or it may be that consciousness is a separate entity from the brain.

Wired: This seems to verge on supernatural explanations of consciousness.

Parnia: Throughout history, we try to explain things the best we can with the tools of science. But most open-minded and objective scientists recognize that we have limitations. Just because something is inexplicable with our current science doesn't make it superstitious or wrong. When people discovered electromagnetism, forces that couldn't then be seen or measured, a lot of scientists made fun of it.

Scientists have come to believe that the self is brain cell processes, but there's never been an experiment to show how cells in the brain could possibly lead to human thought. If you look at a brain cell under a microscope, and I tell you, "this brain cell thinks I'm hungry," that's impossible.