Why is it that we can see these multiple histories play out on the quantum scale, and why do lose sight of them on our macroscopic scale?

Many physicists believe that the answer lies in a process known as quantum decoherence.

Does conscious observation of a quantum system cause the wavefunction to collapse? The upshot is that more and more physicists think that consciousness – and even measurement – doesn’t directly cause wavefunction collapse.

In fact probably there IS no clear Heisenberg cut. The collapse itself may be an illusion, and the alternate histories that the wavefunction represents may continue forever. The question then becomes: why is it that we can see these multiple histories play out on the quantum scale, and why do lose sight of them on our macroscopic scale? Many physicists believe that the answer lies in a process known as quantum decoherence.