# Q & A: Changing Planck’s Constant

Q:
What would happen if Planck’s constant = 6.26E-20?
- Amber (age 18)
Swansea, UK
A:
This is an interesting question, Amber.

Normally, Planck's constant (usually called h) has a value of 6.2618 x 10^-34 Joule-seconds (J*s). This is an important constant in Quantum Mechanics. So if we were to increase Planck's constant by about 10^14, what would happen?

A lot would change. For one thing, I doubt that there would be any atoms in the universe. The energy required to ionize hydrogen depends on h^-2. Ionizing is giving the electron of an atom enough energy to leave the hold of the nucleus. So if we increase h by 10^14, then the ionization energy of hydrogen would decrease by 10^-28.

That is miniscule compared to the current energy needed to break an electron off of an atom would decrease dramatically. So if you were to excite an atom even a little bit, it would ionize.

Also, even if there were some stable atoms, they would be HUGE. The radius of an atom depends on h^2. So the atom would go from being 0.53 x 10^-10 meters (too small to see) to 0.53 x 10^18 meters. That's 100 times the distance to the nearest star!

So the universe would be completely different if we were to change planck's constant so drastically.