What would happen if Planck constant decreased slightly?

[zonde]

I have speculative question.
What we would expect to see if Planck constant would become marginally smaller?

My guess is that vacuum would start to produce black body radiation. Does it seems right?

 

[Vanadium 50]

There is no way to answer that question as posed. One has to specify exactly which other constants - with different dependencies on the one you change - change and by how much.

 

[zonde]

There is no way to answer that question as posed. One has to specify exactly which other constants - with different dependencies on the one you change - change and by how much.

If we do not consider matter - only vacuum and photons, would it be enough to specify that speed of light is not changed?