On 30-04-2015 09:19, Bruce Kellett wrote:
Stathis Papaioannou wrote:
On 30 April 2015 at 13:20, Bruce Kellett <bhkell...@optusnet.com.au>
wrote:
The way I understand it, nothing happens in Platonia. Which is to
say
nothing ever happens. The real question is why we think stuff is
'happening'. Well, OK - the hallucination that stuff is happening is
what is
happening.
So explain the hallucination. Why does that 'happen'. Note that
'happen' is
a temporal term.
I have the feeling that I have been alive for years, but I would still
have this feeling if I had only been alive for seconds. There does not
have to be a physical, causal connection between the observer moments
of my life for them to form a subjective temporal sequence. The
sequence is implied by their content.
The brain in the vat is always possible. We cannot rule out solipsism
either.
Julian Barbour, in his book 'The End of Time' tried to abolish time
altogether because of the difficulties of defining time in general
relativity. He replaced time as a parameter with the notion of 'time
capsules' present in every point of phase space.
It is not really clear whether this idea was successful or not. It has
not attracted a great following.
But if any such idea is to make sense, the observer moments do have to
be connected by quite strong causal laws so that the sequence of
moments tells a coherent story. Or else each moment tells a different
story, and we are back with 'Last Tuesdayism' or solipsism.
I don't think Fred Hoyle's account works either. It feels like a 'many
minds' collapse interpretation of quantum mechanics.
Bruce
You can use the formalism developed in this article:
http://arxiv.org/abs/1305.1615
If we take finite time steps corresponding to a computational step, then
an observer momement is defined by specifying some operator:
sum over {in} of| j1,j2j3,...jn><i1,i2,i3...in|
where the jk are functions of the i1,...,in.
This then simplify specifies that a computation proceeds from an initial
state defined by the sequence of numbers i1,i2 etc. to the next step
defined by the numbers j1,j2 etc.
The summation has some finite range, so the algorithm is not defined
precisely. On the other hand, the fact that the summand contains more
than just a single term means that the state of the system is not well
defined. The more terms there are in the summation, the better defined
the computation becomes, but the state of the system becomes less well
defined.
A computation that is complex enough to represent what the brain is
capable of will contain an astronomically large number of terms;
whatever consciousness is and how it works, from experience we know that
what we feel and think doesn't contain enough information to nail down
exactly what the brain is doing.
This means that in a MWI picture, it is wrong to represent the branches
as single lines, they are bundles consisting of an astronomically large
number of lines, the correlation contained in them contain a vast amount
of information, more than what you need to define what computation is
actually being performed at any instant.
Anyway, I think that Bruno should consider deriving physics from
starting with defining observer moments as matrix elements O = sum over
i of |j><i| and then physics should be derived by introducing more
degrees of freedom and then finding a generator of O. So, you invent a
universe described by a Hamiltonian so that running the laws of physics
starting from some initial conditions will allow you to properly
represent O.
Then one considers that particular representation that requires the
least amount of information given some O. Then one should consider also
minimizing that information over the possible ways of defining O (note
that O being defined by a summation indicates that O itself doesn't know
what state it is in).
Anyway, these are my thoughts that I have not yet developed much. I have
looked into of some of the mathematical details of how one could proceed
further, and so far it looks worthwhile to do more work on it.
Saibal
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