The h-bar hat has the symbol ħ, a variation on Planck’s constant h. ħ = h/2π. ħ has a value of 1.054571817…×10⁻³⁴ J⋅s/rad or 6.582119569…×10⁻¹⁶ eV⋅s/rad.
Usually we don’t include the radian in the unit.
Planck needed this constant to help describe the behaviour of black-body radiation. He could only get the proper description by adding in quantization of the energy that was emitted. This discovery lead to quantum mechanics.
Dad hats aren’t just for dads. This one’s got a low profile with an adjustable strap and curved visor.
- 100% chino cotton twill
- Unstructured, 6-panel, low-profile
- 6 embroidered eyelets
- 3 ⅛” (7.6 cm) crown
- Adjustable strap with antique buckle
- Blank product sourced from Vietnam or Bangladesh