By Caroline McClatchey
BBC News Magazine
There were jokes and rumours about black holes as the Large Hadron Collider was switched on. Children picked up on these fears - so how to reassure young ones about the Big Bang machine?
"What is this experiment about, Daddy, and is it going to blow up the Earth?"
That was the question many parents collided with as scientists prepared to flick the switch on the Large Hadron Collider in Switzerland.
In the run-up to the switch-on on Wednesday, doomsayers predicted the £5bn machine could create a world-ending black hole. One teenager was so terrified, she committed suicide in India.
A black hole of the imagination, courtesy of Dr Who
Educational psychologist Alex Griffiths says hearing that the world might end can be "devastating" for a child of a certain age.
While children in the later stages of primary school may not understand the physics, they certainly have a good understanding of what this might mean for them and their families.
Although the sense of self is developing from an early age, an awareness of reality does not emerge until at least the age of five.
"Generally, adults can rationalise situations and just get on with life. Children have more time to play with the idea and it is new to them.
"Their brains are not as well developed and they have little experience of scaremongering to draw from. It also appeals to their imagination."
This experiment has played on children's fears, just as the prospect of nuclear annihilation did during the Cold War, and the swirling rumours about the new millennium.
Mr Griffiths says such scaremongering is unlikely to have any long-term effect on children's mental health.
Jade and Leah needed a reality check from their father
Marc McLean's two daughters Leah, 10, and Jade, eight, heard about Cern and the end of the world in the playground.
"The kids weren't crying but they were really concerned something catastrophic was going to happen. There had been a lot of talk about it in school and they also saw it on the news."
Mr McLean, from East Kilbride in Lanarkshire, says Jade was particularly upset. He was not sure how to handle her questions at first.
"I listened to Stephen Hawking talk about it and he said the experiment was going to be absolutely microscopic in comparison to the real Big Bang so that reassured me. I told my kids that to try and reassure them."
While Mr McLean does not like to see his daughters upset, he hopes to encourage their interest in science and does not think they should be shielded from it.
It was also a hot topic on the Mumsnet discussion board, with many stories of children crying themselves to sleep.
One mother told how her children went around the house on Wednesday morning "ritually saying goodbye to pets, toys, rooms, house", while a seven-year-old told her mother she would "stab herself in the heart so she dies straight away".
Justine Roberts, co-founder of Mumsnet, says while there was an element of "gallows humour" in some of the messages - one son was said to be "typing his will, gathering photos of the family to look at in his dying moments" - there was genuine concern about how to console a doom-addled child.
But as well as consolation, parents found it a welcome chance to talk to their offspring about the experiment itself. Her two nine-year-olds were more clued-up than she was, and were able to fill in the gaps in her knowledge.
"Children often take these things in their stride - though some can internalise issues only for them to appear later," Ms Roberts says. She recommends that parents be "overwhelmingly reassuring", even if they harbour nagging doubts.
"If you look evasive, your child will pick up on that. Answer them directly but give the minimum amount of information. And dealing with worse case scenarios is part of growing up."
Psychologist Alex Griffiths suggests focussing on the reality and risk, keeping the science simple and the outlook positive.
Such as? "Experimentation is a good thing. Government and scientists are not going to spend large amounts of money on something that could harm us. Lots of thought will have gone into it and what is likely to come out of it."
While a child's questions may appear deep and distressing, this shows a healthy interest in the world.
"If they are talking about things, not just what they ate for breakfast, that has to be good. It might motivate them into learning more about the world."