The bright flash occurs because when sperm enters and egg it triggers calcium to increase which releases zinc from the egg. As the zinc shoots out, it binds to small molecules which emit a fluorescence which can be picked up my camera microscopes.
To be clear, the headline is a little deceptive. Buried toward the end of the article is this statement: "In the experiment, scientists use sperm enzyme rather than actual sperm to show what happens at the moment of conception." Obviously, sperm enzymes aren't enough to fertilize an egg and create a new human being. So the flickers of light you see in the video aren't actually the first moments of nine people's lives. It just looks the same. (From a pro-life perspective, that's a good thing; this was a "basic science" study rather than an attempt to help infertile parents, so if actual embryos had been created, they probably would have been destroyed.)
Even so, I get why pro-life groups are sharing this, because it is very, very cool. And the article is refreshingly clear about conception being the point where life begins. There is no obfuscation. The very first line of the article is "Human life begins in bright flash of light as a sperm meets an egg, scientists have shown for the first time, after capturing the astonishing ‘fireworks’ on film."
Which is why the rest of the article is so incredibly disturbing.
Not only is it an incredible spectacle, highlighting the very moment that a new life begins, the size of the flash can be used to determine the quality of the fertilised egg.
Researchers from Northwestern University, in Chicago, noticed that some of the eggs burn brighter than others, showing that they are more likely to produce a healthy baby.The embryos that flash brightest are supposedly the healthiest, while the dimmer-flashing embryos are presumed defective.
"This means if you can look at the zinc spark at the time of fertilization, you will know immediately which eggs are the good ones to transfer in in vitro fertilization. It’s a way of sorting egg quality in a way we’ve never been able to assess before."That's right, kids. After a brief moment of awe at the marvel of human life, researchers quickly moved on to figuring out which embryos should have a chance to live and which should be summarily destroyed.