# The Value of Newton's Gravitational Constant $G$ within an Atom

Can the value of Newton's Gravitational Constant $G$ be measured within a stably bound atom?

PLEASE NOTE: Since scattering experiments do not involve stably bound systems, their results are not germane to the specific question asked here.

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We can't measure gravitational effects in an atom because they're far too small. However we can measure effects like hyperfine splitting to great precision, and we would see if there was an contribution from gravity - needless to say no such effects are seen, which is exactly what we would expect if $G$ inside the atom is the same as $G$ at the large scale. –  John Rennie Feb 1 '13 at 17:16
There is theoretical justification for $G$ becoming large at very short distances/energies, but we're talking about the Planck scale and there is no currently foreseeable way we'll ever be able to probe that scale directly. –  John Rennie Feb 1 '13 at 17:18