How a proton gets its spin is surprisingly complicated
In an odd twist, rarer up antiquarks add more angular momentum than more plentiful down antiquarks
![proton spin](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2019/03/032019_EC_proton-spin_feat.jpg?fit=860%2C460&ssl=1)
SPIN SURPRISE Protons are composed of smaller particles, called quarks and antiquarks, which contribute angular momentum, or spin. Now scientists report that a rarer type of antiquark adds more to the proton’s spin than a more common variety.
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