# Appearance of new information: mirror of collapse?

1. May 31, 2010

A lot has been written about the relative merits of decoherence versus the many-worlds theory in answering the question: where does the extra information go when a superposed state "collapses" to a definite state. However, what about the reverse: when the definite state returns to a new superposed state, where does the new information come from? For the decoherence advocates, I can imagine an answer that it comes from the environment, but for the many-worlds theory, I cannot imagine an answer.
I suspect I am on the wrong track altogether, and would like to be put straight. Thanks.

2. May 31, 2010

### Dmitry67

In MWI, there is no need to inject additional information, because the wavefunctions ALWAYS covers ALL the posibilities, forming the Universum. And Universum has 0 information. That's is, there is no information in the God's view in MWI!

Example:
We are in the 'Universe' of integer numbers.
Look at a list: 3,444
It contains some information, right?
Now add more numbers: 3,444,54032823, 9349349, 55858
But look at list

All numbers except 44,55,66
All numbers except 44,55
All numbers except 44
All integer numbers!

Filling last 'holes' you reduce information by adding numbers. Finally, all integer numbers contain the same information as an empty set - nothing! So Universum does not contain any information.

1. MWI is based on the Decoherence.
2. In MWI information exists - on observer's level. As observer always has limited view (small finite list of numbers in my toy example) he has some information.

Yes another example. Imagine 2 people playing chess, recording their moves. But if they play for infinite time or there are infinite number of partners, playing all possible moves, then the whole game is reduced to the list of rules, there is no information

Last edited: May 31, 2010
3. May 31, 2010

### zonde

When measurement is performed possibility is reduced to certainty. That is increase in information. What you lose are possibilities not information.

4. May 31, 2010

### Geigerclick

Unless you have MWI, in which case you simply limit your personal observations, but the possibilities remain.

5. May 31, 2010

### Dmitry67

Also I dont understand this oart of the question:

because MWI is a logical consequence of Decoherence (not the only option, but anyway)

6. May 31, 2010

### Galap

MWI can also be said to not only describe all the possible futures that can come from an event, but also all possible histories that led up to it. I hope this answeres the question.

7. Jun 1, 2010

### zonde

As long as my personal observations are limited to one particular world possibilities are lost in that particular world.

8. Jun 1, 2010

### Geigerclick

That is a valid philosophical position, but not a physical one in this hypothetical scenario.