i thought about this as well, when i first learned about unification of forces, it seems like an obvious thing to try and reason about, so let's go! [caveat -

i thought about this as well, when i first learned about unification of forces, it seems like an obvious thing to try and reason about, so let's go! [caveat - i'm not a physicist, but] we know forces unify at higher temperatures/energies, and there is no limit to how high temperature can get (maybe? i guess temperature is the same as the mean velocity of the particles, so for particles with mass this cannot exceed c, right?) however the the high energy zone is inaccessible with current technology above a certain level. but in the other direction, we hit a floor at zero kelvin. which we can access, and can therefore test. so we know that going right down to zero kelvin / electron-volts / joules / meteres per second does not split any of the known forces further. this is how we know that they are the fundamental forces, i think.