Wiseman left ages ago, but I’m taking a stab at this question because 1) I want to know if my answer is right, and 2) other people who read it might want to know the answer too.
since the whole universe includes separate branching “worldsâ€[sic], and over time this means we have more worlds now than 1 second ago,
As far as I can tell from this sequence, the number of worlds that exist over time, or at least the total amplitude, is constant. Multiple “past” configurations contribute amplitude to the same “present” configuration. Any given “past” configuration also contributes amplitude to multiple “present” configurations. The scare quotes are because neither the question nor the answer makes much sense if one considers timeless physics.
As far as I can tell from this sequence, the number of worlds that exist over time, or at least the total amplitude, is constant.
If you take the MWI literally, each world splits all the time, so the number of worlds would increase. Of course, there is no point counting what we cannot observe, not even in principle.
the total amplitude, is constant
Depends on what you mean by that. But yes, one can certainly express the MWI in a way that preserve unitarity over multiple worlds.
Multiple “past” configurations contribute amplitude to the same “present” configuration.
Probably not in this sense. The world splitting process ought to be a tree graph, with no cycles. Scott Aaronson explains it better.
The scare quotes are because neither the question nor the answer makes much sense if one considers timeless physics.
You may want to ponder how rational it is to refer to an exciting idea that was never fleshed out as if it were a real physical model.
Wiseman left ages ago, but I’m taking a stab at this question because 1) I want to know if my answer is right, and 2) other people who read it might want to know the answer too.
As far as I can tell from this sequence, the number of worlds that exist over time, or at least the total amplitude, is constant. Multiple “past” configurations contribute amplitude to the same “present” configuration. Any given “past” configuration also contributes amplitude to multiple “present” configurations. The scare quotes are because neither the question nor the answer makes much sense if one considers timeless physics.
If you take the MWI literally, each world splits all the time, so the number of worlds would increase. Of course, there is no point counting what we cannot observe, not even in principle.
Depends on what you mean by that. But yes, one can certainly express the MWI in a way that preserve unitarity over multiple worlds.
Probably not in this sense. The world splitting process ought to be a tree graph, with no cycles. Scott Aaronson explains it better.
You may want to ponder how rational it is to refer to an exciting idea that was never fleshed out as if it were a real physical model.
My understanding is “Yes, but only if the resulting ‘present’ configurations are identical, which basically never happens when things get big.”
That’s what Scott says, yes. There is related to Poincare recurrence, something that happens probably just as often as two worlds combining.