The uncertainty principle states the uncertainty in energy and time can be related by Δ Δ E Δ Δ t ≥ ≥ 1 2 ℏ ℏ , where ⁠ 1 / 2 ⁠ ħ ≈ 5.272 86 × 10 J⋅s. This means that pairs of virtual particles with energy Δ Δ E and lifetime shorter than Δ Δ t are continually created and annihilated in empty space. Although the particles are not directly detectable, the cumulative effects of these particles are measurable. For example, without quantum fluctuations, the "bare" mass and charge of elementary particles would be infinite; from renormalization theory the shielding effect of the cloud of virtual particles is responsible for the finite mass and charge of elementary particles.