On 11 January 2014 11:20, Stephen Paul King <stephe...@provensecure.com>wrote:

> Dear LizR,
>   I am trying to get a somewhat complicate question out and understood.
> Let me state it crudely: Given the infinite number of possible 1p content
> that the UD can "run", how do we obtain from the UDA or UD or UD* the
> situation that we believe to be true: that there exists a space-time that
> *contains* some huge number of observer -each with its own 1p- *and* the
> appearance of interactions among them *and* a set of physical laws, GR and
> QM that have a mathematical structure that prohibits the assumption of an
> absolute 1p that "could see everything all at once"?
> BTW, there are empirical reasons to strongly doubt that space-time has
> some form of granularity, as such would violate SR by making signal
> propagation velocities dependent on the energy of the photons. Ultra high
> energy and medium energy gamma rays have been observed to arrive
> simultaneously (modulo small error bars) from sources that are millions of
> light-years away. This makes the notion of "quantized" space-time dubious.
> Apparently the jury is still out on this - see the 4/1/14 edition of New
Scientist with the (typically non-sensationalist :) headline "BREAKING
RELATIVITY - The celestial signals that defy Einstein", which claims the
opposite - that BRB130427A (from a distance of some billions of light
years, redshift 0.34) had a delay of 100s of second between low and high
energy gamma rays. This is the most energetic event observed to date (on
27/4/13). Also, on 30/6/05, the MAGIC telescope in the Canary Islands
detected a gamma ray burst from half a billion light years away with a 4
minute delay between the low and high energy radiation. There is also some
data from the Ice Cube neutrino observatory that indicates hints of an
energy dependent time lag in neutrino bursts...

But there are other observations that don't show these features, plus there
are some assumptions involved that may change how we interpret them, and so
on. What is needed of course is "more light!" - as observations continue it
should become clearer whether there is some dispersion (maybe only at gamma
ray energies that even GRBs struggle to reach very often, which would
indicate that the granularity of space-time is quite small) - or not, in
which case any granularity that exists would have to be very small, even
compared to the Planck length,

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