In
a previous blog entry, I quoted from The
Anthropic Cosmological Principle, and today, I’ll look at something else in
the book, since it’s a really fascinating book with lots in it (though you don’t
have to have read the previous post to understand this):
From The Anthropic Cosmological Principle by John
Barrow and Frank Tipler (1988):
“Unified
theories also show us why we observe the World to be governed by a variety of ‘fundamental’
forces of apparently differing strengths: inevitably we must inhabit a
low-temperature world…and at these low energies the underlying symmetry of the
World is hidden.”
Before getting into the real idea of this, this picture gives the basic idea of what we'll be looking at:
The
key point to remember is that higher energies mean smaller scales: so if you go
inside atoms and probe fundamental particles, that will be at higher energies and
temperatures than, say, the energy of a baseball flying through the air,
despite the fact that it’s a lot bigger. Early in the history of the universe,
energies and temperatures were much higher than they are now, and that is when
these forces would be truly unified. This might be easier to grasp if you think
of nuclear fusion and fission: there’s a lot of energy stored up inside atoms, as
we can see with nuclear bombs that use only a small amount of matter but
release huge amounts of energy.
In
many physics theories, these are only the first hints of what is known as grand unification, which is not, as it
sounds, some political scheme for world domination, but the unification of the
physical forces at high enough energies. The ideas is that at low energies, we
see these forces as separate, just like with, say, electricity and magnetism,
but as you go up to higher energies, which represent smaller scales and smaller
particles, these forces unite. Although we haven’t observed it yet, this means
that the strong force will also join forces with the electroweak force to form
a single “grand unified force” (“electrostrongweak”, perhaps?) at energies of
about 10 to the power of 16 GeV (a GeV is a giga-electron volt. It’s big, let’s
just say. And 10 to the power of 16 is 10 followed by 16 zeros. Also big).
There are many different theories that can realize this unification, and they
are all called Grand Unified Theories, or
GUTs. This can be seen in terms of
group theory: for example, the electroweak force is called a SU(2) x U(1) and the strong force is SU(3), so
combining them gives SU(3) x SU(2) x U(1) = SU(5).*1 That’s
not so important, but what is important is that this SU(5) force acts as its
own force, not simply a patchwork of the other forces, but something different
entirely. This is the hidden “underlying
symmetry” mentioned in the quote: although, fundamentally, all forces are the
same, they split up when the universe cooled to lower energies and so we usually
observe them as distinct, whereas they are actually united, forming a larger
symmetry that we can now only observe when we collide particles at very high
energies to recreate conditions similar to the early universe.
As
can be seen in the picture above, the three forces converge at high energies.*2 This
means that their strengths become equal, and we can see them as being the same
force. The strong force, then, decreases in strength as you go to smaller and
smaller distances, whereas the electromagnetic and weak forces increase in strength
until they meet up.*3 This is very important because if the strength
of the strong force didn’t decrease, it would never meet up with the electroweak
force and would never be united.
Gravity,
however, is a slightly different story. The electromagnetic, strong, and weak
forces all act on very small scales (of course, we observe electromagnetism on
larger scales too, but it’s also very strong on the scales of elementary
particles), but gravity is usually negligible for elementary particles, because
it is so weak (weaker than the weak force, even). But at very high energies, at
what is called the Planck scale (10 to the power of 19 GeV), it is thought that
gravity will also be united with the other three, forming not a GUT this time,
but a TOE (a Theory of Everything). Of course, even if we are able to work out a
theory that united the four known forces, that doesn’t mean that we’ll have a
TOE: there may still be many things left out, such as other forces, other
dimensions, souls, etc. But uniting gravity with quantum mechanics (the other 3
forces that act on a small scale) would certainly be a big step forward.
So
that’s the basic physics idea behind GUTs and TOEs. But if we take it a step
further, it could be possible that this is only a small segment of a larger
process that occurs in the universe. Take one of our “separate” forces, say, the
strong force. What if that force is really the unification of other forces that
have already merged? It would then be a more basic force than they are, but would
split when the universe cooled to lower temperatures. You could go the other
way around too. After gravity, when you have your TOE force (sounds awful, I
know. I’ll call it the Everything-1 force, or E-1), there could be other forces
that could merge with it too. So as you go to higher and higher energies, ones
that are hardly imaginable now but that we may reach in the future, you could
get an Everything-2 force (E-2), then an E-3 force, and so on.
This
could also tie into the notion of higher dimensions, whether physical
dimensions, such as adding a new “direction,” or a spiritual dimension that
encompasses a higher level of existence, like a more enlightened state where
things are less bounded by restrictions imposed by matter. What appears to be
many forces here can in fact be united under a universal law when you are at
higher energies or some form of higher state. As usual, the analogy of the
glass prism works perfectly here: you have a very basic force that acts on
everything, say E-100, and that splits into multiple forces as you go to lower
levels of being, just like white light is split into colours as it passes
through a prism. All the more particular forces, like all the colours, are all just
aspects of E-100, but won’t be united unless they pass back through a
converging prism that reunites them.
This
ties right into Plato’s Forms: the more complex Forms derive from simpler ones
that are more fundamental. These continue splitting as you go to lower levels
of existence until you reach the world here, where there are particular objects
that partake in many of the individual Forms. To reach enlightenment, one must
ascend to higher levels of existence and eventually become one with the higher
Forms. This is common in Neoplatonism, where the goal is to ascend to the One,
which is the highest level of being. This can also be seen in Buddhism: the
more enlightened one becomes, the simpler one’s existence is. Matter is much
more complicated than the Forms, and the lower Forms are much more complicated
than the higher ones of, say, Number, Symmetry, Beauty, and Motion (for
instance, a moving baseball is much more complicated than Motion in general,
because Motion is not a particular motion, but the source that all instances of
motion derive from). In understanding and becoming in tune with the higher
Forms, you can return to the source of all those levels of existence below you
and be able to understand them in a unified way rather than as fragmented from
one another.
So
from a philosophical point of view, the ideas from GUTs and TOEs belong to a
more universal pattern of getting to a more fundamental source, whether that is
a more basic physical law or a higher spiritual existence, and thus, it will
hopefully lead to a more comprehensive view of our universe. But the question
is, where does it stop?
*2 The picture is slightly deceptive because it doesn't show electromagnetism and the weak force uniting before converging with the strong one.
*3 The reason that the electromagnetic force’s strength is greater at smaller distances is because of virtual particles. Electrons can emit virtual photons that can then turn into positron-electron pairs (a positron is an anti-electron). The positrons, being of a positive charge, are attracted to the original electron and screen its charge by cancelling some of it off with their positive charge. At larger distances, there are more of these pairs, and so the force is screened more, but as you get closer and closer to the electron, there is less screening, and so the strength of the force increases on smaller scales, which is at high energies.
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*3 The reason that the electromagnetic force’s strength is greater at smaller distances is because of virtual particles. Electrons can emit virtual photons that can then turn into positron-electron pairs (a positron is an anti-electron). The positrons, being of a positive charge, are attracted to the original electron and screen its charge by cancelling some of it off with their positive charge. At larger distances, there are more of these pairs, and so the force is screened more, but as you get closer and closer to the electron, there is less screening, and so the strength of the force increases on smaller scales, which is at high energies.
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