Abram Demski wrote:
> Brent,
>
> I'm not sure how the comment about real numbers effects my basic
> argument. One interesting objection I got from someone not on this
> list was that time isn't composed of moments at all, only intervals--
> a "moment" is an imaginary thing that we get by considering
> arbitrarily small intervals.
>
This is the same as assuming reals. Real numbers can be defined in
terms of intervals marked by rationals
http://planetmath.org/encyclopedia/DedekindCuts.html
> Mathematically, though, a real-values time variable doesn't eliminate
> moments, it just makes an infinite number of them between any other
> two, with a particular mathematical structure. So the question of what
> makes them "stick together" remains.
>
They come with a topology which is about the only concept of sticking
together I can imagine.
> Obviously, one reason I think that I am traveling through time is
> because I remember the past (but can only guess at the future). But
> "remembering the past" is an experience that takes time, spanning many
> moments, making this a little tangled. The multiverse complicates
> things further: even supposing that only the possible worlds implied
> by quantum mechanics exist (that is, no alternative physics, just all
> possible quantum states) it is quite possible for me to remember the
> future. It's merely improbable. But if all possible alternatives
> actually occur, I don't know what probability means. (Even if there
> are literally more alternatives down the probable paths, does this
> make it more probable that I experience the more probable result? What
> would that mean?)
>
I think probability is useful because it has different interpretations,
relative frequency, degree of rational belief, measure, propensity,
etc. So you may estimate the propensity of throwing snake eyes by
throwing many trials (relative frequency) and then base you bets on the
results (degree of rational belief). So in the case of QM you can look
at the Born rule as defining a measure and then reinterpret it as a
degree of rational belief in order to inform your decisions. The
problem is that the Born rule seems to still have to be adopted as a
separate axiom, thus reintroducing the problem Everett intended to solve.
Brent
> --Abram
>
> On Thu, Dec 18, 2008 at 7:21 PM, Brent Meeker <meekerdb.domain.name.hidden> wrote:
>
>> Abram Demski wrote:
>>
>>> [Sorry if this is a duplicate, I think that I did not send correctly
>>> the first time.]
>>>
>>> Bruno, everyone,
>>>
>>> I've decided that it will be more productive/entertaining to post my
>>> various concerns as a new topic.
>>>
>>> What is time?
>>>
>>>
>> Time is what you read on a clock.
>>
>>> I'm going to ask a bunch of questions; for the sake of brevity, I'm
>>> going to skip my arguments (which would mostly be reasons why
>>> particular answers don't work). I'll argue once someone replies.
>>>
>>> If all possible universes exist, does that mean every possible moment,
>>>
>>>
>> What do you mean by "possible"? Do you mean nomologically possible -
>> which might be very restrictive but we don't know? Or do you mean
>> logically possible - just not instantiating a contradiction "X and
>> not-X"? Or something inbetween?
>>
>>
>>> or every possible timeline of moments? If "moments" is the answer,
>>> then how are the moments connected?
>>>
>> If time is a real variable (which QM assumes), moments automatically
>> inherit the topology of the reals.
>>
>>
>>> How would it matter, since the
>>> moments already are what they are? If "timeline" is the answer, then
>>> there is a similar question of how it matters.
>>>
>>> If there is a physical universe, then is there some sort of basic
>>> physical connection behind time?
>>>
>>> If the universe is mathematical in nature, then what is the
>>> mathematical connection between moments? What sort of mathematical
>>> connection counts as time?
>>>
>>> If (as was recently suggested, in connection with relativity) time
>>> cannot really be divided into individual moments, then what is it?
>>>
>>>
>> In physics, it's a variable in the equations that determines the causal
>> topology.
>>
>>> Why do we experience time passing?
>>>
>>> Is it legitimate to think as if the next moment we experience will be
>>> chosen randomly in some sense? Does probability or randomness have a
>>> role to play in the flow of time?
>>>
>>>
>> Randomness would seem to give a sense to the direction of time. That's
>> why physicist who are loathe to give up time-symmetry in their equations
>> tend to favor Everett's interpretation of QM.
>>
>>
>>> In connection with UDA: what is the meaning of a first-person
>>> probability due to uncertainty of the future? Is there any sense in
>>> which such estimates can be more or less accurate if all possible next
>>> moments do in fact occur?
>>>
>>>
>> Good question. It's the same as asking how the Born rule arises in
>> Everett's interpretation of QM.
>>
>> Brent
>>
>>
>>> Hope that sparks some thought...
>>>
>>> --
>>> Abram Demski
>>> Public address: abram-demski.domain.name.hidden
>>> Public archive: http://groups.google.com/group/abram-demski
>>> Private address: abramdemski.domain.name.hidden
>>>
>>>
>>>
>>
>
>
>
>
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Received on Sat Dec 20 2008 - 00:54:13 PST