Freethought & Rationalism Archive

spacer1 · 08-10-2003, 12:20 AM

Could someone explain to me how the different universes of the MWI are supposed to interact?

I am currently under the impression that only universes which share similar properties can be said to interact. However, taking into consideration randomness and the lack of absolute outcomes, it seems to me that all universes must have a possibility for X to exist or occur. This seems to make all universes equally likely to have similar properties.

All we could say, then, is that an alternate universe is just a universe with some property/ies which are different to how things are in this universe?

NonHomogenized · 08-10-2003, 03:31 AM

As I understand it, the idea is that, each time a possibility has cause to be actualized, universes will exist in which any given possiblity will be actualized, in a probability commisurate with their likelihood (ie, a 1 in 1 million possibility will occur in approximately 1 out of every 1 million universes).

Other than this similarity, there is no interaction, AFAIK, according to MWI.

Undercurrent · 08-10-2003, 11:00 AM

To my understanding, the bleating about universes "branching off" whenever a quantum decision is made is just so much colourful language. The whole jist of the M(M/W)I is that non-unitary wavefunction collapse never actually happens, even with concious observation -- the concious obverserver becomes entanged with the quantum system, just like any other piece of matter would, possibly entering a superposition of classical states, which are called "worlds" only because it is a concious observer in this entagled state, rather than just a bit of inanimate matter. The worlds interact through the same processes by which regular entagled states interact, e.g. interference.

For example, if an electron is in a combined spin-up/spin-down state, we have no conceptual objection to the notion that both states are in our universe, and that we can perform experiements whose results are different because the electron is in an entangled state.

If electrons were concious, we would change the language so that the "up" state of the electron is in a different "world" than the "down" state, so the electron could always maintain its conceit that it is always in a single classical state, at least each world. But the physics would be the same, and so long as we manages to avoid entangling ourselves with the electron, we can make apparati to interact with both of its "worlds" at the same time

08-10-2003, 12:20 AM	#1
spacer1 Senior Member Join Date: Jun 2003 Location: Australia Posts: 564	How do Alternate Universes interact under MWI? Could someone explain to me how the different universes of the MWI are supposed to interact? I am currently under the impression that only universes which share similar properties can be said to interact. However, taking into consideration randomness and the lack of absolute outcomes, it seems to me that all universes must have a possibility for X to exist or occur. This seems to make all universes equally likely to have similar properties. All we could say, then, is that an alternate universe is just a universe with some property/ies which are different to how things are in this universe?

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08-10-2003, 03:31 AM	#2
NonHomogenized Veteran Member Join Date: May 2003 Location: no longer at IIDB Posts: 1,644	As I understand it, the idea is that, each time a possibility has cause to be actualized, universes will exist in which any given possiblity will be actualized, in a probability commisurate with their likelihood (ie, a 1 in 1 million possibility will occur in approximately 1 out of every 1 million universes). Other than this similarity, there is no interaction, AFAIK, according to MWI.

08-10-2003, 11:00 AM	#3
Undercurrent Veteran Member Join Date: Jan 2001 Location: Santa Fe, NM Posts: 2,362	To my understanding, the bleating about universes "branching off" whenever a quantum decision is made is just so much colourful language. The whole jist of the M(M/W)I is that non-unitary wavefunction collapse never actually happens, even with concious observation -- the concious obverserver becomes entanged with the quantum system, just like any other piece of matter would, possibly entering a superposition of classical states, which are called "worlds" only because it is a concious observer in this entagled state, rather than just a bit of inanimate matter. The worlds interact through the same processes by which regular entagled states interact, e.g. interference. For example, if an electron is in a combined spin-up/spin-down state, we have no conceptual objection to the notion that both states are in our universe, and that we can perform experiements whose results are different because the electron is in an entangled state. If electrons were concious, we would change the language so that the "up" state of the electron is in a different "world" than the "down" state, so the electron could always maintain its conceit that it is always in a single classical state, at least each world. But the physics would be the same, and so long as we manages to avoid entangling ourselves with the electron, we can make apparati to interact with both of its "worlds" at the same time

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