However, classical physics led to the Rayleigh–Jeans law, which, as shown in the figure, agrees with experimental results well at low frequencies, but strongly disagrees at high frequencies.
Namun, fisika klasik yang diwakili Hukum Rayleigh-Jeans, seperti pada gambar, hasilnya sesuai dengan hasil eksperimen pada frekuensi rendah, namun kacau pada frekuensi tinggi.