Noble gas molecules are held together by van der Waals forces. These forces are weak attractive forces that exist between atoms or molecules due to temporary fluctuations in electron density. In noble gas molecules, the van der Waals forces are the result of the temporary dipoles that form due to the random motion of the electrons in the atoms. These temporary dipoles induce similar dipoles in nearby atoms, leading to weak attractive forces that hold the atoms together in a solid or a liquid state.