# Do we have any idea why Planck's constant has the value it has? [duplicate]

Since $h$ seems to relate to a fundamental unit of quantization, it only seems right that we should have an idea of why it has the value it has. What do we know?

I understand that to some extent the precise values of universal constants are arbitrary, but when I look at the Bohr model, I see that the angular momentum of electrons comes in discrete levels that appear to be directly proportional to Planck's constant. Which suggests to me that there is something special about this number.

## marked as duplicate by David Hammen, CuriousOne, user259412, Qmechanic♦Aug 14 '16 at 12:16

• Possible duplicate of Why do universal constants have the values they do? – David Hammen Aug 14 '16 at 11:25
• Some countries still use English units. In such a system, with mass in pounds mass, force in pounds force, and acceleration in feet/second$^2$, Newton's second law becomes $F=kma$ as opposed to $F=ma$. Your question is exactly the same as asking about the physical significance of the $k$ in $F=kma$. There is none. That $k$ has to exist in English units simply means that English units are a bit goofy. The exact same reasoning applies to $h$, $c$, and $G$ in SI units. Those constants are just conversion factors. – David Hammen Aug 14 '16 at 12:05
• Energy travels around the universe in discrete units, I just want to know if anyone has discovered why these discrete chunks are the size that they are. Forget Planck if you like. – Alan Gee Aug 14 '16 at 12:16
• @AlanGee: Energy is not quantized, as far as we know. You can have any amount of it that you like. – CuriousOne Aug 14 '16 at 12:17
• In the same way as $c$, $h$ is not at all a mere conversion factor. One instructive example is the use of $ħ$ within the solutions of Schrödinger equation. $e^{i ħ}$ is describing a helix with the radius $ħ$. In this sense, $h$ is describing the size of the components our world is made of. I recommend to reformulate the question such that everybody understands. – Moonraker Aug 14 '16 at 12:47