The sensitivity of the behaviour of thedevices to the behaviour of some tiny atomic-scaleparticles propagates first to the devices and then to the observers

The participation of the agent continues to be

important

even when the only features of the physically

described world being observed are large-scale properties of

measuring devices

. The sensitivity of the behaviour of the

devices to the behaviour of some tiny atomic-scale

particles propagates first to the devices and then to

the observers in such a way that the choice made by an

observer about what sort of knowledge to seek can

profoundly affect the knowledge that can ever be

received either by that observer himself or by any other

observer with whom he can communicate. Thus the

choice

made by the observer about how he or she will act

at a macroscopic level has, at the practical level, a

profound effect on the physical systembeing acted upon.