Sigh.
The problem is that people want to use classical notions, such as waves and particles, as opposed to the actual quantum description.
All *quantum* effects go forward in time. This is true even in the quantum eraser. But, if you insist on thinking of things classically, the results will appear paradoxical.
All paths of the quantum eraser need to be taken into account, including phase information. And, yes, if 'which path' information exists, then no interference pattern occurs. And if 'which path' information is not, then a pattern is seen. This is well modeled in QM and with only forward influences in time.
The problem is that people want to use classical notions, such as waves and particles, as opposed to the actual quantum description.
All *quantum* effects go forward in time. This is true even in the quantum eraser. But, if you insist on thinking of things classically, the results will appear paradoxical.
All paths of the quantum eraser need to be taken into account, including phase information. And, yes, if 'which path' information exists, then no interference pattern occurs. And if 'which path' information is not, then a pattern is seen. This is well modeled in QM and with only forward influences in time.
