Home
Grava Thesis
Grava Strings
Dark Matter
What's New
FAQ
Links  References
Suggestions
Search
Discuss 1
Discuss 2
Discuss 3
Discuss 4
Discuss 5
Discuss 6
 
Discussion on Grava and Cosmology
Page 2
October 29, 2000 Ray via email to Dr. Jim Kennedy:
Hi Jim,
I appreciate your comments and suggestions. I am interested in reading
more about other related concepts, as you suggest.
I certainly appreciate the mathematical models that have been developed so
far. I hope to come up with a framework to inspire more mathematical
approaches and challenges, as well as experiments to prove or disprove some of
the tenants of my grava perspective.
I also wish to ask you a more simple question. Is there anything in my
treatise that strikes you as totally impossible or illogical? I realize
that much of the work is general and based on unstated references.
However,
does it appear to have some glaring faults or an obvious lack of integrity from
your perspective?
Thanks, again.
Ray
October 30, 2000 Dr. Kennedy replies:
Ray:
You have asked a very appropriate question.
As far as I am concerned, nothing should ever be excluded as
"impossible". That's a deadly trap. Nature is smarter than
any of us
and probably does "impossible" things regularly, just to keep us from
getting too arrogant!
I can point to some differences between your point of view and that
which is presented in the Elegant Universe (EU). Generally, these are
not judgments or criticisms, but just pointing to differences 
although there are a couple of suggestions I snuck in.
EU doesn't need a beginning per se. The math works in both directions
time wise. It does permit never ending expansion, but it also permits a
series of expansions and contractions (Big Bangs followed by Big
Crunches). Not withstanding that, it is reasonable to talk about the beginning of the current expansion.
In the EU view, the six plausible mathematical descriptions turn out naturally to be paired in such a way that two of the equations are
actually the same, but somewhat disguised in ways that were not
immediately obvious. The other two sets of equation pairs have the
property that when the universe is squeezed down to a Planckscale size,
further attempts to squeeze the dimensions in one equation cause it to
become the same as its semitwin equation, except that the semitwin is
expanding in size.
This leads to the conclusions that:
1. There do not need to be infinitesimally small spaces with infinite
energy or mass densities; and
2. That a universe undergoing a "Big Crunch" will rebound into a
Big
Bang as soon as it is compressed to a small enough (nonzero) size.
This first conclusion was a breakthrough, because it removes the need
for nonsensical mathematical infinities that arose in previous attempts
to blindly combine relativity and quantum theory.
The second conclusion opens the logical possibility of talking about a
time before the Big Bang.
Philosophically, physicists try to avoid infinities in mass, energy, or
anything else. The concept is ok in mathematical circles, but applying
them in the physical world leads to nonsense results over and over
again. It leads one to suspect that Nature may have a rule against
infinities. So far, when we find ways of describing Nature without
infinities, the answers resemble the things we observe. When we find
them creeping into the mathematical descriptions, the descriptions fail
to look like what we actually see. (For example, an infinite mass would
have infinite gravitational force, and that would apparently collapse
the universe permanently.) The suggestion here is to see if your
explanation can work without postulating infinities.
The concept of "fields" is used in physics to describe (no doubt
primitively) the observation that certain actions seem to take place at
a distance (e.g. an electrically charged object pushes or pulls on
another electrically charged object  without touching each other). It was noticed that one could write three (and later four) dimensional
equations that described how much force would be exerted in what
direction depending on where the two objects were in space (and time)
with respect to each other. In short, in physics, fields are
mathematical constructs that usually describe forces.
It is not clear what you mean when you describe Grava as a field.
Although I must say, in all fairness, a mathematician would say that a
field is any function that describes some (any) property of space (not
just force).
Back to Grava, it sounds like you are visualizing it as some sort of
superspace that contains "regular" spacetime, except that it has
defining powers that lead to establishing rules through some kind of
interaction between the superspace and all the stuff in it.
This is reminiscent of a philosophical dilemma in quantum theory that so
far hasn't gone away. Some people refer to it as "subatomic
communication". Although we really can't tell for sure, at times the
mathematics (that yield good agreement with observation) seems to
"require" atomic particles to "talk" to each other faster
than the speed
of light to negotiate what they are each supposed to do in a particular
interaction. If this is really true, the "plane" upon which this
communication takes place would be interesting indeed. This smacks a
bit of your notion about Grava and negotiation.
Interestingly, EU sees space (whether fourdimensional or eleven) NOT as
"nothing" or "empty" but as a real physical entity.
Space is the
"something" you can put "stuff" (mass/energy) into.
The difference is
that, in EU, the stuff in the space shapes the space, not the reverse
(if that is sort of what you have in mind).
In a sense, EU sees the stuff as "stuck" to the space. When the
universe was a Planckscale object, not only had the matter/energy
shrunk down to that size, but the (however many) spacetime dimensions
had shrunk as well. The WHOLE universe, including the space that held
it, was smaller than a subatomic particle. The small universe contained
ALL its space in that small size, and there was NOTHING (whatever that
is) outside it. When matter/energy expanded, it dragged the space along
with it, warping, twisting, modifying it as it went. The warps, twists,
and modifications give rise to the forces we see today.
In this point of view, everything today is in the same relative location
as it was at (before?) the Big Bang, except that matter/energy has long
since crystallized into separated matter AND energy, which are now
(still) connected through forces that were born when matter/energy was
torn apart into matter and energy, warping space in the process.
Rules in the universe (a fun topic): There has been an ongoing debate
about whether the constants (speed of light, gravitational constant,
mass of fundamental particles, the Planck energy constant, etc.) are
universal values existing for all times and places, or just local
traffic rules appropriate for only a particular region of spacetime. In
particular, are they time dependent?
Is the time it takes for a signal to get from point A to point B in the
universe a fixed value? If space is expanding, so is the
"distance"
between point A and point B. If the time is constant, the speed of
light is increasing. The opposite argument says the speed is
decreasing. Then there is the issue of what one means by "time",
in a
world where spacetime is still drastically shrunk just after a Big Bang.
We don't know the answer. We have seen events in quasars (when the
universe was about 15% of its present age since the (most recent) Big
Bang) that suggest that the speed of light was much faster then.
However, there is also evidence to suggest that this interpretation is
the result of an optical illusion. Obviously, if the speed of light has
changed over time, all our concepts about the AGE of the current
universe will be off, one way or the other.
The notion that the values of the "universal" constants depends on the
amount of matter/energy in the universe (whether or not they change in
space or time) is certainly plausible. This is consistent with the
ideas of Eddington (fixed, finite amount of matter/energy in the
universe) and Mach (everything pulls on everything else).
Dimensions of energy, mass, time, and 3D space: a full description in
only these terms would have to answer why the different particles have
the masses they have, and how the measured forces between particles
arise. This is a main driver for EU and its extra dimensions. If
they
extra dimensions are not necessary, the theory will have to explain what
IS necessary.
The observational evidence is that there are families of matter
particles (leptons and quarks). The members of these families
(mathematically) behave as if they were harmonically related within
their particular family (e.g. the electron, muon, tau, etc. all have the
same sets of characteristics except they have different masses). It is
also true that they have a number of other quantized characteristics
that seem to be independent of each other (e.g. electrical charge seems
to have nothing to do with the "spin").
In the macroscopic world, harmonic relationships are only found in
oscillating systems, pendulums, mass/springs, guitar strings, etc.).
Mathematically independent characteristics imply (mathematically)
orthogonal dimensions. So the approach described in EU says, "let's
imagine that there are closed loops of "something" that can oscillate.
And, "let's assume that there is a different, orthogonal axis
(dimension) for each independent characteristic".
The "model" actually assumes that these (perhaps seven) extra
dimensions
actually have some physical reality and are related to the three
familiar spatial dimensions. This assumption NEED NOT to be true for
the mathematics to actually produce meaningful results in describing the
behavior of the particles (as you suggest).
This fact has spawned a series of calculations and proposed experiments
to try to detect the extra dimensions in the physical world. The jury
is still out...
Let me go further to add, though, that if the dimensions are only
mathematical, and not physical, then it will beg the next question: Why
are the answers harmonic? Any comprehensive theory will have to be able
to answer that question.
As noted, in the EU approach the rationale for forces is that "space"
is
distorted by the present of matter/energy, making space have an
uphill/downhill orientation in one respect or another. Since the
different particle characteristics are manifested by forces, the current
thinking is to postulate spaces for each of the characteristics. Thus,
there is the focus on the physical reality of the proposed extra dimensions.
Special cases and unstable events: Physicists shy away from concepts
that require Nature to develop specialcase handling. One would like to
have a schema that was sufficiently robust that it could handle
anything, without special cases. I don't think you need to worry about
special rules.
In that spirit, I'm not sure how to interpret the comments about
isolation of, say, black holes. The evidence is that they are no more
isolated than a person, planet, or star, in the sense that they are
fully participating members of the cosmos. They interact
gravitationally with everything else in the universe.
They profoundly effect the space near themselves. The fact that they
don't emit light (or anything else) from WITHIN the event horizon makes
them a bit extreme, but they do send out signals of one sort or another
that originate just beyond the event horizon. They cause enormous Xray
emission as a result of their shearing through nearby matter, and at
least one theory says they put out a lot of fundamental particles from
the same region. (By the same token, the light we see from a normal
star doesn't come from "inside" the star, it comes from the region
immediately above the visible "surface" of the star.)
There are some very inhospitable places out there, from a human
perspective, but Nature seems to be ok with that. There are streets in
LA I wouldn't caught dead on too (for fear that I might be!).
Let me add one more thought (that was mentioned in EU and also the
Hawking book I mentioned). In the EU picture, where matter/energy can
shrink no smaller than a certain small size, the state of matter in a
Black Hole is very similar to that at about the time of a Big Bang. This raises the question of how much mass does it take before something
can shrink to the critical limit where it spontaneously begins to expand
again.
Are some (every?) Black Holes creating new universes? If so, are they
popping out is some other space (not here)? Is their time so distorted
compared to our viewpoint that they are actually expanding inside their
event horizon in "our space" but so slowly we can't tell? Is the
inside
of their event horizon just a totally different space and they will do
everything they will EVER do, without it ever looking any different from
here? Are we ourselves simply living on the inside of a Black Hole?
At the end of the day, we have to keep looking for answers. There is no
guaranty that EU is it.
Jim
More Discussion
