1998 Bonestell Lecture presented by Dr. Kai Woehler
HOW DOES NATURE CHOOSE
BETWEEN ALTERNATIVE UNIVERSES?
The Origin of the Universe by a Process of Natural Selection
STRINGS AND STRINGY SPACE
About the Big Bang and Black Holes
THE DEEP STRUCTURE OF MATTER AND FORCES
About Elementary Particles and Forces
SYMMETRIES - PRINCIPLES OF DESIGN
About the Search for the Holy Grail--The Theory of Everything
STRINGS AND STRINGY SPACE
About Hidden Dimensions
OUR UNIVERSE--A VERY SPECIAL PLACE
About Worlds Hospitable to Life
About the Origin by Natural Selection
|If particles cannot be points, what can they be?
They could be little spheres or lumps. They could be little doughnuts, or little strings or string loops, or little pieces of membrane. Of these simpler possibilities the strings and string loops are the simplest alternatives to point particles. It turned out to be a very powerful model.
|Strings, like violin strings can oscillate in different ways, thus representing different kinds of particles in a unified way. These strings or string loops are assumed to be of very small size. One must ask then: how small?|
|What gives a hint how small small is? The only
indication physics gives is the so called PLANCK LENGTH. The only length that can be
constructed of the fundamental constants of physics is this Planck Length. It is
constructed in a unique way from light velocity, the Planck quantum of action and the
gravitational constant. This length is incredibly small. If the size of your fingernail
were enlarged to the size of the universe, the Planck Length would be the size of a
fingernail. (it is realized that this comparison merely shifts the incomprehensibility of
the very small to that of the very large).
Collisions between strings no longer have the zero distance problem of point particles and it was expected that there would be no more dreaded infinities in real calculations.
* There are thousands of different point particle theories in principle, with the right ones selected by finding all the conservation laws that nature obeys. However there seem to exist only five types of string theories. These five theories, in order to properly incorporate quantum physic, must be for strings that move in nine space dimensions.
|This is a surprising reduction of possible theories
compared with point particle theories. Moreover, during recent years, since 1994 it became
clear that these five theories in nine space plus one time dimension are actually five
different phase, different aspects of one underlying theory, a 11-dimensional theory
called the M-THEORY, which I like to call the MOTHER OF ALL THEORIES.
This theory is related to an earlier 11-dimensional theory for point particles that is mentioned in the earlier Tree of theories. These five theory cousins are tamper proof. There is nothing that can be fundamentally changed in these theories. They are unique. This fact holds the promise that one may actually have arrived at the "only uniquely possible theory of everything.
*However, it turns out that this does not mean that we have the HOLY GRAIL in hand. In order to have a theory that gives a world with three expanded dimensions out of a theory written in terms of nine space dimensions, seven of these space dimensions must be curled-up somehow to Planck size. And there it turns out, that there are thousands, perhaps millions of ways in which this reduction to only three extended dimension could be accomplished. The number of possible structure patterns of seven curled-up dimensions appears to be staggering. The important point here is that EACH OF THESE PERHAPS MILLIONS OF WAYS OF CURL-UP LEADS TO A DIFFERENT WORLD WITH DIFFERENT KINDS OF PARTICLES AND DIFFERENT KINDS OF FORCES.
These are all possible solutions of the one unique theory. Below is shown a feeble cartoon of a two dimensional universe space with different patterns of one curled-up dimension. In each of these possible solutions the structure of the underlying pure space, the STATE OF THE VACUUM, is different.
|If this universe has that many possibilities to be
structured out of just one fundamental string theory, how did our universe manage to come
up with just those patterns that give the types of particles and forces that we do
observe? What, or WHO made the selection?
Before we report on one possible answer, let us see what string theory does to our notions of the nature of space.
We must talk about STRINGY SPACE. In Einstein's Theory the structure of space is described by certain MEASURES OF GEOMETRY. In our extended space these measures, the so called metric coefficients, appear to be very closely to the value 1. 0 . Quantum theory demands that we cannot make such quantitative statement with total certainty. This value 1. 0 is only an average of very many measurements. We must accept that these values undergo fluctuations continuously. The magnitude of these quantum fluctuations, it turns out, are determined by how large a patch of territory we are trying to measure. A patch the size of an atom is extremly large compared to the Planck Length.
|Quantum theory the estimates that the size of the
fluctuations is the incredibly small, unobservable with any of our tools. A patch the size
of a few Planck-Length, however, will have very large fluctuations. On that scale space
would appear as having deep holes, steep mountains, throats, tubes and tunnels.
Space on that level could be visualized as having a multiconnected foam like structure, like a sponge. One might visualize this by flying high above the ocean. From that distance the ocean surface looks ver flat. Sitting however in a small canoe on the surface of the ocean one might find oneself overwhelmed by the mountainous waves.
|With this "Quantum Foam Structure" of space
at the very smallest scales, what kinds of phenomena might one expect to be possible? Here
are some suggestions:
|We can now go a step further. If strings are the
fundamental entities of everything, then a close view of space would reveal that space
itself is but a network of strings which represent gravitons that are continuously
interacting with each other, moving shifting, merging, parting, a tapestry of threads that
from afar looks like a smooth space.
NOTHINGNESS in this view, that means the absence of organized space and matter would be some chaotic pattern of such interacting strings, structureless ever changing in rapid pace. Emergent extended space and matter would be the manifestation of some pattern of order in this network of interacting gravitation like strings.
Rudiments of a String quantum theory of Gravitation that have been constructed so far are using loops and knots as the basic organization patterns that constitute space. There are possibly millions of such organization patterns each representing a different kind of universe, each with different kinds of particles and forces.
Now we are approaching finally that haunting question how out of millions of possible universes our special universe may have been selected. Before we present the latest ideas on this let us first stop and reflect about some features of our universe.
OUR UNIVERSE--A VERY SPECIAL PLACE
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