Mathematicians get annoyed at how physicists take beautiful formulas and clutter them up with 'useless' constants like

𝑐 - the speed of light
ℏ - Planck's constant
𝑘 - Boltzmann's constant
𝐺 - the gravitational constant

making it harder to see the essence of things. Mathematicians prefer units where all these constants are set equal to 1.

I used to be like that too - but right now I'm doing a project where I 𝑛𝑒𝑒𝑑 these constants to see the essence of things!

(Of course it's good to keep these constants around so you can use dimensional analysis to avoid mistakes: this is what computer scientists call a 'type discipline'. That's important, but it's NOT what I'm talking about now.)

When you're studying just one physical theory at a time, you can set dimensionful constants equal to 1 to simplify things. But often we like to study a whole 𝑓𝑎𝑚𝑖𝑙𝑦 of physical theories at once - a family where those constants take different values! We can't set them to 1 if we're interested in what happens when they approach 0. For example:

As 1/𝑐 → 0, special relativity reduces to Newtonian physics.
As ℏ → 0, quantum mechanics reduces to classical mechanics.
As 𝑘 → 0, statistical mechanics reduces to classical mechanics.
As 𝐺 → 0, general relativity reduces to special relativity.

And this is just the beginning of the story: various collections of constants can approach 0 at different rates, and so on.

When we do this, we're studying what mathematicians would call a 'moduli space' of theories - or even better, a 'moduli stack'. We may want to do 'deformation theory', where we expand answers in powers of some constant. And so on.

So don't scorn those constants!

Walking through walls training system

"This invention is a training system that enables a human being to acquire sufficient hyperspace energy in order to pull the body out of dimension so that the person can walk through solid objects such as wooden doors."

https://patents.google.com/patent/US20060014125A1/en

(Application abandoned.)