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<img src="cid:part1.08060900.08020207@solution-consulting.com" title=""
alt="anthropic universe" width="733" height="390"><br>
<br>
Here is a nice illustration of the anthropic principle I thought
you might enjoy.<br>
<br>
<br>
Premise Checker wrote:<br>
<blockquote type="cite"
cite="midPine.NEB.4.63.0510162159250.28834@panix3.panix.com"> Oct
6th 2005
<br>
<br>
An explanation for the anthropic principle comes a little closer
<br>
<br>
DID God have a choice? Or, to put the matter less theologically,
does
<br>
the universe have to be the way that it is? The answer to this
<br>
question, posed by Einstein among others, remains elusive. But it is
<br>
important, not least because a universe with laws only slightly
<br>
different from those actually observed would be one in which
life--and
<br>
therefore human life--could never have come into existence.
<br>
<br>
That observation, known as the anthropic principle, disturbs many
<br>
physicists because they cannot see any fundamental reason why things
<br>
could not be different. In particular, they cannot see why space has
<br>
to have three dimensions. But a paper due to be published this month
<br>
in Physical Review Letters by Andreas Karch of the University of
<br>
Washington and Lisa Randall of Harvard University suggests that the
<br>
laws of physics may, indeed, be biased towards three-dimensions.
<br>
Curiously, though, they have a similar bias towards
seven-dimensions.
<br>
<br>
The idea that there may be more dimensions than the familiar ones of
<br>
length, breadth and height (and also, to be strictly accurate, the
<br>
fourth dimension of time) is a consequence of attempts to solve an
old
<br>
problem in physics. Ever since Einstein developed his theories of
<br>
space, time and gravity, physicists have sought a "theory of
<br>
everything" that would unite those theories with quantum
<br>
mechanics--the part of physics that describes electromagnetism and
the
<br>
forces that hold atomic nuclei together. Such a theory would, it is
<br>
hoped, describe how the universe developed from the Big Bang. It
would
<br>
explain why there appears to be more matter than anti-matter. It
would
<br>
even indicate the nature of the dark energy and dark matter that
lurk
<br>
at the edge of perception.
<br>
<br>
To date, the best candidates for a theory of everything are various
<br>
versions of a branch of mathematics called string theory.
<br>
Unfortunately for common sense, these theories require the universe
to
<br>
have ten or even 11 dimensions rather than the familiar three of
space
<br>
and one of time. To get round this anomaly, some physicists propose
<br>
that the familiar dimensions are "unfurled", while the other six or
<br>
seven are rolled up so tightly that they cannot be seen, even with
the
<br>
most powerful instruments available. For an everyday analogy, think
of
<br>
a thread of cotton. This appears one-dimensional for most purposes.
<br>
Only under a magnifying glass are the other two dimensions
<br>
perceptible.
<br>
<br>
A second interpretation of multidimensionality, however, is that the
<br>
extra dimensions are not always rolled up, but that even when they
are
<br>
not humans cannot readily observe them because they are not free to
<br>
move in them. In this version, the space inhabited by humans is a
<br>
three-dimensional "surface" embedded in a higher dimensional
<br>
landscape. The particles of which people are composed, and the
<br>
non-gravitational forces acting on them, are strictly confined to
this
<br>
surface--called a brane (short for membrane)--and, as such, have no
<br>
direct knowledge of the higher dimensional space around them. Only
<br>
gravity is free to pervade all parts of the universe, which is one
of
<br>
the reasons why it obeys a different set of rules from the other
<br>
forces.
<br>
<br>
It is this second interpretation that is invoked by Dr Karch and Dr
<br>
Randall. They assume that, initially, the universe was filled with
<br>
equal numbers of branes and anti-branes (the antimatter equivalent
of
<br>
a brane). These branes and anti-branes could take any number of up
to
<br>
ten different dimensions. Dr Karch and Dr Randall then demonstrated,
<br>
mathematically, that a universe filled with equal numbers of branes
<br>
and anti-branes will naturally come to be dominated by 3-branes and
<br>
7-branes because these are the least likely to run into their
<br>
anti-brane counterparts and thus be annihilated.
<br>
<br>
This result is interesting for two reasons. It is the first piece of
<br>
work to show that branes alone can explain the existence of hidden
<br>
dimensions. They do not have to be rolled up to be inaccessible. It
is
<br>
also the first to suggest an underlying preference in the laws of
<br>
physics for certain sorts of universe, and thus perhaps provide a
<br>
solution to the anthropic principle. Yet it is not a total solution.
<br>
Other realities, whether three- or seven-dimensional, could be
hidden
<br>
elsewhere in the landscape. And life in seven-dimensional space
would
<br>
look very different from life on Earth--if, indeed, it existed at
all.
<br>
That is because the force of gravity would diminish far more quickly
<br>
with distance than it does in this world. As a result,
<br>
seven-dimensional space could not have planets in stable orbits
around
<br>
stars. Like dark matter and dark energy, therefore, the anthropic
<br>
principle is still grinning from the sidelines, taunting physicists
to
<br>
explain it.
<br>
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<br>
</blockquote>
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