Everywhere you point, a faint hiss: the oldest light there is, set free when the universe first turned transparent. Stretched by fourteen billion years of expansion, it now glows at just under three degrees above absolute zero — the most perfect blackbody nature has ever shown us.
A true Planck blackbody spectrum B(λ,T) is plotted live over a logarithmic temperature dial (0.5 K → 30,000 K), and Wien's displacement law λ_peak = b/T (b = 2.898×10⁻³ m·K) marks its peak — both real physics. At T = 2.725 K the peak sits at ~1.06 mm, deep in the microwave; that is the measured CMB temperature, and the CMB matches a blackbody to better than one part in 10⁴ — the most perfect blackbody known. Slide the temperature and Wien's law slides the peak (hotter → bluer, the Sun at 5772 K peaking in the visible) exactly as drawn.
'The first light / the universe turned transparent' is the recombination story (real, ~380,000 years after the Big Bang). The instrument shows a single blackbody curve and Wien's law, not the full CMB power spectrum with its acoustic peaks; and the band labels are indicative. The physics of the curve is exact; the cosmic narration is the frame.