Are atoms expanding as the Universe expands?

The forces that bind atoms together most likely overpower the large-scale effects of expansion.

Asked by: Tony Karger, Norfolk

The expansion of the Universe only significantly affects space and time on scales bigger even than entire clusters of galaxies. Below this, the size of objects is dictated by far stronger influences, notably the force of electromagnetism in the case of atoms. Extremely sensitive measurements have found no evidence that the fundamental properties of atoms are anything other than constant.

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