Jim Chapman didn't think it was possible until it happened to him.
In the fall of 1999, after suffering a heart attack while exercising at a local fitness club, Chapman said he came back from what should have been a one-way trip. He was rushed to the hospital in an ambulance. But after half an hour of resuscitative treatment, Chapman's heart stopped beating.
Later, doctors told him that his heart ceased functioning for 2½ to four minutes. But during the time doctors declared him clinically dead, Chapman said he felt as if he wasn't even in the hospital.
"I know when my heart stopped there was a consciousness that continued from being in the ER," Chapman, 59, said. "Everything went silent. When I opened my eyes, I was standing on the edge of a valley, with the sun shining and the breeze on my face."
When he looked to his left, he said he saw "a shimmering area" that coalesced into his family. After the picture of his family faded away, Chapman said he became overwhelmed by a feeling of exhilaration.
When he blinked again, he said he was back in the ER, on the gurney, facing a nurse and doctor.
No longer a cynic, the retired Canadian broadcaster said his near-death experience changed his outlook on life.
According to conventional science, when people's hearts stop beating and they stop breathing, the brain shuts down and consciousness disappears. That school of thought believes that without the brain, consciousness isn't possible.
But a new study launched earlier this month will test a different theory: that consciousness is not localized to the brain and when the brain ceases functioning, the mind can continue to exist.
Led by Dr. Sam Parnia, an expert in the field of consciousness at the United Kingdom's University of Southampton, the study will monitor brain activity during cardiac arrest and test the validity of near-death and out-of-body experiences.
Called the "world's largest-ever study of near-death experiences," the Aware (Awareness During Resuscitation) study is a collaboration between 25 hospitals in the United Kingdom and the United States. U.S. participants include Indiana State University, Rosalind Franklin University of Medicine and Science, the University of Virginia and New York University, according to a spokesman for the University of Southampton.
Parnia said he has been "studying what happens when we die and near-death experiences for more than 12 years. What got me interested in it was seeing patients that I was taking care of die. ... And as I watched the people flatline, I wondered, what happened to this person that was thinking? Has their consciousness been annihilated?
"I realized this hasn't been properly tackled by science," he said.
During a cardiac arrest, Parnia said, the three criteria of death are present -- the heart stops beating, the lungs stop working and the brain shuts down.
But death is a process that can continue for hours or days and not a specific moment, he said. Additionally, contemporary medical advances make the process reversible in some cases.
Now that science can bring people back to life, he said, it's important to know what happens to the mind during the process.
Parnia said a number of recent studies conducted by independent researchers have shown that 10 to 20 percent of people who go through cardiac arrest and clinical death report near-death experiences.