Radioactivity
Henri Becquerel
He discovered spontaneous radioactivity while studying uranium salts.
The problem
A question worth answering.
The source of radiation from uranium compounds was unknown.
What they did
He discovered spontaneous radioactivity while studying uranium salts.
What changed
His observation opened experimental study of radiation.
Where you meet their legacy
In the knowledge, systems and people who carry the work forward today.
Evidence and further reading
This story does not assign sole credit for a collective achievement.