>> john geiger, exporer and author has been investigating this phenomenon for years. lays out his theory. >> the story is always similar. there's a sense of another being, a presence very vividly. there's never any fear or panic when this being appears. there's just a sense of calm, peace. >>. >> reporter: it happened to stephanie schaub. >> i'm about as religious as a piece of wood. >> reporter: while cave diving she suddenly lost her guide rope. in an instant, her life was on the line. >> i suddenly realized i was in trouble. i could hear my heart bouncing in my ears. and i just kind of sat down on the floor and started crying. i never cried under water before. >> reporter: only weeks before stephanie's husband had died in a diving accident in the red sea. and now alone, she's facing her own dark death. >> reporter: suddenly t >> suddenly the cave brightened up. >> reporter: the words of her husband -- believe you can, believe you can't. either way, you're right. >> i thought i saw was a white thread. my guide line is white. so i floated up and lo and behold it was

chemist-type, can i borrow a geiger counter. yeah, right over there. you et the geiger counter. you know what a geiger counter is? a radioactive-- radiation detector. and you put the carbon under the geiger counter, okay? you put the new one in there. the new one. from the little twig. huh? you put that under there. click, click, click, click, click, click, click, click, click, click, click, click, click, click, click. maybe 20 counts per minute. make believe. 20 counts per minute. now, you take that away. now you take the old one. put it underneath there. click, click, click, click, click, click, click, click. 10 counts per minute. ooh. how old is the ax handle? check your neighbor. how many of you say, "oh, i think it's something like more than 5,000 years old." show of hands. yay. 'cause it's a half-life. what if you put it under there and it went click, click, click, click. five counts per minute. and the new stuff is 20. ooh. then how old is the ax handle, gang? 11,000. 11,000 or something. 11,460. twe that? yay. maybe twice as old as the half-life. you got it? all right. h

a very concrete survival mechanism that is -- you know, part of our human heritage. >> reporter: geigerves that in a life-threatening crisis, our minds experience the terror of the moment and the peace of perspective. >> and then the brain is able to stand back from that, and sort of rise above that. and it rationally figures out a way to help this person get through that. >> reporter: so the guardian angel is us? >> the guardian angel is us. >> it's interesting. the guardian angel is us. >> chills, yeah. >>> coming up here on the broadcast, matt damon's new vow to his wife. find out the promise he made in front of the entire family. coming up in "pop news" after this quick break. you see the "mini" ion my chest? funny, yes? no. there's nothing mini about me. i'm huge. ahem. any hoo. even my wrapper has a wrapper. flavor? i'm bursting with it. creamy? i ooze it. quality like this... (muffled):...doesn't come everyday. well technically it does because i'm in the grocery but... ooh, how you doin'? rich. creamy. and 100% natural cheese. mini babybel. snack a little bigger. wthe sadness, an

. >> our geiger counter confirms the radiation is twice as high as normal. this nuclear waste is in a fishing zone, and the barrels continue to rust in silence. >> remember, you can find out more about these and many more stories at our website, dw.de. >> thanks very much for joining us. we will see you next time. captioned by the national captioning institute --www.ncicap.org-- q