This is a critique of this advocacy, point by point. See especially Q14, re QFT. This gives a reason why MWI is not a useful object of study.
The first critique seems to criticize something different that Eliezer says. It seems like the person quoted by the author did not express themselves clearly, and the critique takes a wrong explanation. For example this part:
When do worlds split?
The precise moment/location of the split is not sharply defined due to the subjective nature of irreversibility, but can be considered complete when much more than kT of energy has been released in an uncontrolled fashion into the environment. At this stage the event has become irreversible.
How can irreversibility be subjective if it defines what a measurement is and when worlds split? It would imply that when worlds split is also a subjective matter. But then it is observer-dependent, the very thing the interpretation is trying to avoid.
For me the Eliezer’s explanation of “blobs of amplitude” makes sense. There is a set of possible configurations, which at the beginning are all very similar, but because some interactions make the differences grow, the set gradually separates into smaller subsets. When exactly? Well, in theory the parts are connected forever, but the connection only has epsilon size related to the subsets, so it can be ignored. But asking when exactly is like asking “what exactly is the largest number that can be considered ‘almost zero’?”. If you want to be exact, only zero is exactly zero. On the other hand, 1/3^^^3 is for all practical purposes zero. I would feel uncomfrotable picking one number and saying “ok, this X is ‘almost zero’, but 1.000001 X is not ‘almost zero’”.
The quoted person seems to say something similar, just less clearly, which allows the critic to use the word “subjective” and jump to a wrong conclusion that author is saying that mathematics is observer-dependent. (Analogically, just because you and me can have different interpretations of ‘almost zero’, that does not mean mathematics is subjective and observer-depended. It just means that ‘almost zero’ is not exactly defined, but in real life we care whether e.g. the water we drink contains ‘almost zero’ poison.)
So generally for me it means that once someone famous says a wrong (or just ambiguous) explanation of MWI, that explanation will be forever used as an argument against anything similar to MWI.
The first critique seems to criticize something different that Eliezer says. It seems like the person quoted by the author did not express themselves clearly, and the critique takes a wrong explanation. For example this part:
For me the Eliezer’s explanation of “blobs of amplitude” makes sense. There is a set of possible configurations, which at the beginning are all very similar, but because some interactions make the differences grow, the set gradually separates into smaller subsets. When exactly? Well, in theory the parts are connected forever, but the connection only has epsilon size related to the subsets, so it can be ignored. But asking when exactly is like asking “what exactly is the largest number that can be considered ‘almost zero’?”. If you want to be exact, only zero is exactly zero. On the other hand, 1/3^^^3 is for all practical purposes zero. I would feel uncomfrotable picking one number and saying “ok, this X is ‘almost zero’, but 1.000001 X is not ‘almost zero’”.
The quoted person seems to say something similar, just less clearly, which allows the critic to use the word “subjective” and jump to a wrong conclusion that author is saying that mathematics is observer-dependent. (Analogically, just because you and me can have different interpretations of ‘almost zero’, that does not mean mathematics is subjective and observer-depended. It just means that ‘almost zero’ is not exactly defined, but in real life we care whether e.g. the water we drink contains ‘almost zero’ poison.)
So generally for me it means that once someone famous says a wrong (or just ambiguous) explanation of MWI, that explanation will be forever used as an argument against anything similar to MWI.