I want to continue developing our spacetime model in
some of its more sophisticated aspects. We need to know about left- and
right-handed particles and why there are no right-handed neutrinos. We’ll show
that when you have the correct spacetime model, these esoteric subjects aren’t
as intimidating as they’re sometimes made to seem.
We’ll consider only the fermionic points for now. As
we saw here, they are
pulled together by gravity, but because they are fermions, they can’t all have
the same position, so they are held apart by degeneracy pressure. At the end of
inflation, they are as close together as the degeneracy pressure will allow.
Each point (actually each point quad, see here) is trapped
in a more or less spherical cell whose walls are other fermionic points. Within
their cells, the points’ positions vary randomly from one time tick to the
next. This vibrational energy has a ground state, approximately the Planck
energy, 1019 GeV, but because each point vibrates independently of
the others, over any significant volume of space this energy averages to near
zero and we don’t see it. Some of the points are stationary, remaining in the
same point cell from one time tick to the next, but most move to an adjacent
point cell between time ticks. At any time, there are 1017 moving
points for every stationary point. This number is determined by the Higgs
field.
We’ve said that the points’ positions vary randomly
from time tick to time tick, but what about the time between ticks? Well,
according to Einstein’s theory of special relativity, distance and time are
interchangeable, so spacetime looks the same whether we treat both position and
time as random or ascribe all of the randomness to position and treat time as
regular. Since it doesn’t matter, we elect to treat time as regular.
Particles
In addition to its ground state, each point can be
in excited states with energy above the ground state. The first excited state,
with twice the ground state energy, is stable. We see the energy above the
ground state as a particle. We see excited stationary points as electrons and
excited moving points as neutrinos. By the way, this doesn’t mean that
electrons never move. A moving electron is some quantum superposition of a stationary
excited point and a speed-of -light moving excited point, while a neutrino is
100% a moving excited point.
Neutrinos
A neutrino is a resonance of a fermionic point moving at the speed of light. It moves one point cell for each time tick, but its creation time oscillates around the global time. In other words, its instantaneous velocity oscillates above and below the speed of light, c. Now imagine that you are riding on a photon traveling parallel to a neutrino. When the neutrino’s speed drops below your speed, c, you see it behind you, spinning to the left. When the neutrino speeds up, it passes you and you see it ahead of you, spinning to the right!. So is it lefthanded or righthanded? Actually, it is both. When its velocity is less than c it is lefthanded and seems to have mass. When its velocity exceeds c it is righthanded and has imaginary mass. On average, neutrinos have zero mass and travel at the speed of light, but half the time they look like massive particles and half the time they are tachyons, sterile and undetectable.
That
brings us to an esoteric little concept called weak isotopic spin, or weak
isospin, or just isospin. It’s not hard tp see that electrons and neutrinos are
really the same particle, except that one moves at the speed of light and the
other is what we consider stationary, at least when compared to the speed of
light. Physicists say that electrons and neutrinos are a weak isospin doublet.
They morph into each other by exchanging W and Z bosons in a process known as
the weak interaction or weak force. When one changes to the other it is said to
undergo a weak isospin rotation or an SU(2) rotation, where SU(2) is the
special unitary group of transformations with two elements. What’s actually
rotating here? We are dealing with four-dimensional spacetime, but each point
has its own local four-dimensional version of that spacetime, and it doesn’t
have to line up with the observer’s or global version. An isospin rotation is
really just a rotation of the local time axis with respect to the global time
axis. When the local time axis lines up with the global time axis, we have a
stationary particle, an electron. When the local time axis lines up with zero
global time, we have a speed-of-light particle, a neutrino. Remember that the
theory of special relativity says that to a stationary observer, time seems to
stop for an object moving at the speed of light. The W and Z bosons just take
care of the bookkeeping needed to do the standard model calculations.
The
“spin” in the name isospin got there because physicists knew the
electron-neutrino symmetry signaled the existence of a new quantum number that
had to be intrinsic, like spin. They still don’t know what’s really going on,
and they have no idea that position and time are also intrinsic to spacetime
points. They don’t even know that points exist.
Now
back to handedness. There are both lefthanded and righthanded electrons. Apply
an isospin rotation to a lefthanded electron and you get a lefthanded neutrino.
Apply an isospin rotation to a righthanded
electron and you get…nothing. Neutrinos aren’t detectable when they’re
righthanded. Conclusions? There are no righthanded neutrinos, and righthanded
electrons are an isospin singlet (i.e., they have zero isospin).
OK,
enough for now. I hope I’ve shown that even some concepts—like isospin—that are
puzzling to physicists are really pretty straightforward when you know what’s
going on.