# frequency of cosmic background radiation

We see this radiationtoday comingfrom the surfaceof last scattering(which is really a sphericalshellof "nite 4})}\] $f_{\gamma} = 160.23 \; \text{GHz}$ Gamma radiation () is dampened when it penetrates lead. Radiation, in general, exists throughout nature, such as in light and sound. There is much less understood about what kind of "cosmic background" may exist for gravitational waves than for electromagnetic waves.