<p>This idea, known as <a href="http://en.wikipedia.org/wiki/Novikov_self-consistency_principle#Time_loop_logic">Time loop logic</a> has been investigated by Moravec, Deutsch and Aaronson.</p>

CC BY-SA 3.0
2014-02-22T20:28:54.403Z
2014-02-22T20:28:54.403Z
Antonio Valerio Miceli-Barone
<p>Has any research been done on paradox-driven computers?</p>

<p>An example of what I mean by "paradox-driven":</p>

<p>Given a computer which can send information back through time, an algorithm to instantly break passwords would be:</p>

<pre><code>crackPassword(){
    String password=recieveFromFuture();
    if (password.checkIfCorrect()){
        sendToPast(password);//no paradox generated, valid password found.
    }else{
        sendToPast(password++);//paradox generated, this "parallel universe" cannot exist.
    }
    return password;
}
</code></pre>

<p>Since every parallel universe which does not contain a correct password is impossible, the user will continue on one or more valid "parallel universes".</p>

<p>This allows for the solution of any problem in O(1) time, so long as the answer is easily verified.</p>

<p>To the user this would appear as if the program immediately jumped to a valid password.</p>

CC BY-SA 3.0
2014-02-22T19:57:50.270Z
You should look into the research for "*closed time-like curves*".
Niel de Beaudrap
CC BY-SA 3.0
2014-02-22T23:50:20.353Z
Apparently Gödel was interested in similar questions. He developed solutions to Einstein's equations that imply closed time-line curves. AFAIK physicists do not think this can make physical sense, but I am no expert on this at all. I think I have seen that some people try to use it for logical construction like yours, but it is a faint memory.
babou
CC BY-SA 3.0
2014-02-22T23:58:02.037Z
Hm... In theory, could quantum computers be programmed using programs like this?  It would obviously require a really good compiler.  (This seems much easier to understand)
Kent
CC BY-SA 3.0
2014-02-23T00:00:19.420Z
@Builder_K: the short answer is simply "no". A slightly longer answer is "definitely not".
Niel de Beaudrap
CC BY-SA 3.0
2014-02-23T01:11:56.293Z
For examples besides CTCs, you may find several interesting examples of "paradox-driven" computation in Douglas Adams' *Hitchhiker's Guide* series, but unfortunately I think none have been taken as seriously by researchers yet.
usul
CC BY-SA 3.0
2014-02-23T01:13:29.797Z
Related: "Quantum Bogosort" http://en.wikipedia.org/wiki/Bogosort#Related_algorithms , "Hypercomputation" http://en.wikipedia.org/wiki/Hypercomputation
usul
CC BY-SA 3.0
2014-02-23T09:01:25.580Z
@Builder_K The [work of Gödel](https://en.wikipedia.org/wiki/G%C3%B6del_metric) is unrelated to quantum theory, afaik. It starts with the equations for General Relativity. - - - - - - - - - - I think the OP deserves more than a null or negative vote, or did I miss something unreasonable in the question. I fear that ignorance may sometimes be a bit arrogant. Negative voters should have the courage of saying why. Would Kurt Gödel get negative votes if he came here anonymously? - - There is also that the vote can be changed only when the question is edited, even if the voter realizes his mistake.
babou
<dc.parallel-comp>
paradox-driven computers?
Kent
# paradox-driven computers?

(Asked by: username_0 on 2014-02-22)

Has any research been done on paradox-driven computers?
An example of what I mean by "paradox-driven":
Given a computer which can send information back through time, an algorithm to instantly break passwords would be:
crackPassword(){
    String password=recieveFromFuture();
    if (password.checkIfCorrect()){
        sendToPast(password);//no paradox generated, valid password found.
    }else{
        sendToPast(password++);//paradox generated, this "parallel universe" cannot exist.
    }
    return password;
}

Since every parallel universe which does not contain a correct password is impossible, the user will continue on one or more valid "parallel universes".
This allows for the solution of any problem in O(1) time, so long as the answer is easily verified.
To the user this would appear as if the program immediately jumped to a valid password.

**Tags:** dc.parallel-comp

> **Comments:**
> **username_1**: You should look into the research for "*closed time-like curves*".  
> **username_2**: Apparently Gödel was interested in similar questions. He developed solutions to Einstein's equations that imply closed time-line curves. AFAIK physicists do not think this can make physical sense, but I am no expert on this at all. I think I have seen that some people try to use it for logical construction like yours, but it is a faint memory.  
> **username_0**: Hm... In theory, could quantum computers be programmed using programs like this?  It would obviously require a really good compiler.  (This seems much easier to understand)  
> **username_1**: @Builder_K: the short answer is simply "no". A slightly longer answer is "definitely not".  
> **username_3**: For examples besides CTCs, you may find several interesting examples of "paradox-driven" computation in Douglas Adams' *Hitchhiker's Guide* series, but unfortunately I think none have been taken as seriously by researchers yet.  
> **username_3**: Related: "Quantum Bogosort" http://en.wikipedia.org/wiki/Bogosort#Related_algorithms , "Hypercomputation" http://en.wikipedia.org/wiki/Hypercomputation  
> **username_2**: @Builder_K The [work of Gödel](https://en.wikipedia.org/wiki/G%C3%B6del_metric) is unrelated to quantum theory, afaik. It starts with the equations for General Relativity. - - - - - - - - - - I think the OP deserves more than a null or negative vote, or did I miss something unreasonable in the question. I fear that ignorance may sometimes be a bit arrogant. Negative voters should have the courage of saying why. Would Kurt Gödel get negative votes if he came here anonymously? - - There is also that the vote can be changed only when the question is edited, even if the voter realizes his mistake.  

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## 1 answers

### Answer by username_4 on 2014-02-22. Score: 9 | Accepted answer

This idea, known as [Time loop logic](http://en.wikipedia.org/wiki/Novikov_self-consistency_principle#Time_loop_logic) has been investigated by Moravec, Deutsch and Aaronson.


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