Why did they form at that time? Astronomers know from observing distant exploding stars that the size of the universe has been getting bigger since the Big Bang. When the hydrogen and helium atoms ...

The question of where atoms comes from requires a lot of physics to be answered completely — and even then, physicists only have good guesses to explain how some atoms are formed.

Curious Kids is a series for children of all ages. If you have a question you'd like an expert to answer, send it to ...

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The question of where atoms comes from requires a lot of physics to be answered completely – and even then, physicists like me only have good guesses to explain how some atoms are formed.

Most of the universe’s hydrogen and helium atoms formed around 400,000 years after the Big Bang, which is the name for when scientists think the universe began, about 14 billion years ago.

An element is what scientists call a group of atoms that are all the same, because they all have the same number of protons. When did the first atoms form? Most of the universe's hydrogen and helium ...

Discover how CPL’s ongoing free ScienceConnections series inspires hands-on STEAM learning for kids through creative programs ...