- When you point your flashlight at the wall and turn it on, it seems

the light ray reaches the wall instantaneously, and so "speed of light*for everyone watching*" = c = ∞. Or equivalently**c⁻¹ =**1/c = 1/∞ =**0**.

**c⁻¹ ≠ 0**,

**c⁻¹ = 1**(or something else if you prefer another unit system, but

**never 0**). Speed of light is finite and the same

*for everyone watching*. Surprising, yes, but it works for really fast things and that's proven. No biggie.

- When you cut a stick in half, then cut the half in half, then get a

knife, cut the rest into something even smaller, sharpen the knife, and

so on, it feels like you can do this for ever, and with infinite time

"it*makes sense*to have something infinitely small to almost size zero" and we note this idea**ħ = 0**.

**ħ ≠ 0**,

**ħ = 1**(or something else if you prefer another unit system, but

**never 0**). It doesn't

*make sense*

to have laws governing something infinitely small. Surprising, yes, but

it works for really small things and that's proven. No biggie.

- When a needle falls to the ground, it is pulled down by the gravity

from entire Earth (and that's really really big). But you can pick it up

with a tiny magnet. So gravity seems so ridiculously small compared to

other forces that in this perspective, we are almost tempted to ignore

it as if it didn't exist:**G = 0**.

**G ≠ 0**,

**G = 1**(or something else if you prefer another unit system, but

**never 0**).This is not so surprising since you see an apple fall. No biggie.

So we thought that c⁻¹ = 0, ħ = 0 and G = 0, but we now

**know**that c⁻¹ = 1, ħ = 1 and G = 1 and we want one

**consistent**theory starting from there.

The theory behind c⁻¹ = 1, ħ = 0 and G = 0 is called

**Special Relativity**.

The theory behind c⁻¹ = 0, ħ = 1 and G = 0 is called

**Quantum Mechanics**.

The theory behind c⁻¹ = 0, ħ = 0 and G = 1 is called

**Newton's law of universal gravitation**.

The theory behind c⁻¹ = 1, ħ = 0 and G = 1 is called

**General Relativity**.

Other combinations have different theory names, but the one you asked for was:

The theory behind c⁻¹ = 1, ħ = 1 and G = 0 is called

**Relativistic Quantum Mechanics**.

We have no consistent theory for c⁻¹ = 1, ħ = 1 and G = 1, even

though we know it is true. This problem is called "quantization of

gravity". A candidate theory is

**Loop Quantum Gravity**. Another, more famous one is

**String Theory**.