|MadSci Network: Physics|
This is a tough question. Two of the forces (the weak and strong nuclear forces) have limited ranges, so it's possible to imagine a distance at which they don't have an effect. However, the other two forces (electromagnetism and gravity) both utilise exchange particles of no mass and therefore both these forces have infinite range. It's therefore difficult to imagine any realistic situation in which one of these forces can act without the other also being present. That said, perhaps there is a cheat! As energies increase, towards values such as those found in the earliest moments of the universe, the fundamental forces become steadily unified. We could therefore imagine a moment, within the Planck Time of the start of the Big Bang (<10^-43 seconds), when there was only one fundamental force. Regards, Andy Goddard
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