Re: Optimal Prediction

From: Bill Jefferys <>
Date: Wed, 27 Mar 2002 11:38:47 -0500

At 9:19 AM +0100 3/27/02, Juergen Schmidhuber wrote:
>Bill Jefferys wrote:
>> >At 2:25 PM +0100 3/26/02, Juergen Schmidhuber wrote:
>> >But unfortunately the anthropic principle does not have any
>> >predictive power. It does NOT predict there won't be any flying
>> >rabbits tomorrow.
>> But Hoyle did use the AP to predict specific facts about nuclear
>> energy levels, which were subsequently found to be true. So your
>> first statement isn't correct, IMO.
>> Bill
>The anthropic principle only says that the conditional probability
>of finding yourself in a universe compatible with your existence
>equals 1. So all the AP predicts is that our universe will remain
>compatible with our existence. This is trivial.
>You are claiming the AP necessarily implies a specific fact about
>nuclear energy levels? I greatly doubt that - can you give a proof?

Yes, I can.

(Watch for breaks if this wraps).

This is the classic paper where Hoyle shows this. It has been cited
repeatedly in the literature on the AP as an example of a genuine
prediction of the AP. For example, Barrow and Tipler cite it in their

>Even if you could:

I just did.

>there are many possible continuations of our
>universe that do allow for our continued existence and in which the
>energy levels are as they are now and in which flying rabbits do

I don't care about flying rabbits. Stick to the issue at hand. You
claimed that the AP has no predictive power. Hoyle showed almost 40
years ago that it did by making specific predictions about nuclear
energy levels. The facts that he predicted were not known when he
made them, but were subsequently found to be the case.

>My point is that the AP cannot explain at all why they
>should not occur (as long as they don't kill us).
>But the theory of universal inductive inference can:

Suit yourself.

Received on Wed Mar 27 2002 - 08:46:58 PST

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