But I thought I'd take the opportunity to let him talk a little bit about the science behind the science fiction. We've all heard the hullabaloo regarding faster-than-light neutrinos and the possible discovery of the Higgs boson (yes, the two are related, because if FTL neutrinos existed, the Higgs couldn't, or likely wouldn't). Let's hear some stuff about it from someone who knows.
-Stephanie Osborn
http://www.stephanie-osborn.com
~~~
“
‘But oh, beamish nephew, beware of the day,
If
your Snark be a Boojum! For then
You
will softly and suddenly vanish away,
And
never be met with again!’
— The Hunting of the Snark, by
Lewis Carroll
The recent
announcement from CERN about the possible discovery of the Higgs
boson, called by some the God particle for its supposed role in
providing mass to the elementary particles, has stimulated
unprecedented interest in particle physics but also a lot of
questions about just what it means.
In this article I
will discuss what the Higgs boson is, why it is important, and where
the particle physics community will go from here. In order to get
there, I will take some apparent detours, as well as saying some
potentially outrageous things. Well, outrageous to physicists.[1]
The article is
divided into sections on the meaning of mass, the standard theory of
elementary particles, why the Higgs boson is considered important to
the origin of mass, how the search for the Higgs boson was conducted
and the results obtained so far, and the future direction of Higgs
boson research and the consequences for both physicists and
non-physicists.
What is mass,
and why do I need to lose weight?
Before we consider
how the Higgs boson generated mass, we need to have an understanding
of exactly what mass is in the first place.
Ask a classical
physicist what mass is, and you will likely get a blank stare. The
problem is that, even since the days of Sir Isaac Newton, physicist
have had two answers to that question. First, mass is known to be
inertia, the resistance of a body to a change in its state of motion.
In the simplest form of Newton's laws, the mass m of a body
can be defined as the ratio of the quantity of force applied to a
body, F, to the acceleration a of that body generated
by the applied force; or algebraically,
m=F/a.
However, in
classical physics, two (or more) bodies generate a force on each
other which seems to exist simply because the bodies possess inertial
mass. This force, the gravitational force, is such that the force on
one body, of mass m, directly proportional to the mass M
of the second body in the system, and inversely proportional to the
square of the distance r between them,
Fgravity=GMm/r2
In this equation,
the constant G, called Newton's constant, serves primarily to
make sure that the units work out properly. If the two masses are in
kilograms (kg), and the distance is in meters (m), then to yield F in
the self-consistent metric system units of newtons (N), the constant
G has the value of 6.67 x 10-11 Nm2/kg2.
This number seems absurdly small (written in decimal notation it is
0.0000000000667), until you realize that it is defined so that, if M
is the mass of the Earth, and r is the radius of the Earth,
the acceleration experienced by the mass, m, is equal to the
acceleration of gravity on the surface of the Earth, 9.8 m/s2.
This really just shows how weak gravity is in conventional use, if
it takes the entire mass of the Earth to generate just one "g"
of gravity.
The identification
of two different types of mass, inertial and gravitational, does not
answer the question of where mass comes from. Much less the question
of why, in consistent units, inertial and gravitation mass are equal.
When it came time for Albert Einstein to ponder this question, while
developing the general theory of relativity, he just accepted that
the two types of mass were the same, a simplified statement of what
is known as the principle of equivalence.
However, relativity
introduces other concepts necessary to understanding the essence of
mass. First, there is a relationship between kinetic energy, or
energy of motion, of any material body, and its mass; this is the
origin of Einstein's best-known equation, E=mc2. Second,
this leads to the definition of rest mass, or the mass of any
material body when it is not in motion relative to an observer,
usually designated as m0. Third, this also
means that the mass of a body in motion (relative to an observer)
appears to increase — in particular, part of the energy which a
force imparts to the body results in an increase in speed, and part
of the energy results in an increase in mass. As the body approaches
the speed of light, the mass increases without bound, and so it takes
infinite energy just to reach the speed of light, at which point the
body has infinite mass.
However, this
assessment doesn't apply to photons, the individual quantum particles
that make up light. Since, by obvious definition, light travels at
the speed of light, photons are very different from any material
body. Photons are thus considered to be massless - they have no
mass, and thus are constrained to always move at the speed of light
to maintain their existence. (In principle, the other force carrying
particles of the standard model — the intermediate vector bosons of
the weak force, the gluons of the strong force, and the gravitons of
the gravitational force — are also expected to be massless. This
is clearly not true for the intermediate vector bosons, as we will
discuss in the next section; the gluons and gravitons will be
considered in the final section.) However, photons still possess
energy, by virtue that they also possess momentum, and one central
tenant of Einstein's general theory of relativity is that
gravitational forces can also affect photons. In the theory, this is
because the gravitational forces act by warping space-time, which
changes the pathways along which the massless photons travel, leading
to such phenomena as gravitational lenses which are becoming a useful
tool in astronomy. However, the same effect would be encountered if
the gravitational force is assumed to act on energy densities, rather
than on masses, and Einstein's theory also makes that assumption.
And thus, we come
to the classical "handle" on the origin of gravitational
mass: any concentration of energy reacts to gravity, and thus
gravity maybe a phenomenon of energy concentrations rather than of
masses. All of this is true, but it is well hidden in gravitation
theory. The relevant equation, which is what physicists refer to as
Einstein's equation (not the much better known and much simpler; it
is provided here primarily because it has recently appeared
(bizarrely, and with a small error) in a popular movie[2]
Rμν-(1/2)gμνR=(8πg/c4)Tμν,
where the
quantities R (a 4 x 4 matrix in the dimensions of space-time)
describe the curvature of spacetime, the quantities g, called
the metric, defines the coordinate system used to describe space
time, and the quantity T is the energy density which causes
the gravitational field.
But as noted,
gravity is not the only force. The electromagnetic force is
significantly more powerful; the electromagnetic force between two
electrons is stronger than their mutual gravitational force by a
factor of 1040 or
10,000,000,000,000,000,000,000,000,000,000,000,000,000. Other than
the direct effects of gravitation — falling bodies, the unsightly
numbers we observe every time we step on the scale (if we can look
down that far) — everything else we observe on a macroscopic scale
on earth is due to the electromagnetic force. We feel the shock when
we pick up static electricity walking across a carpet - that shock
represents only a very small number of electrons. The forces that
hold all of matter together, from the table I am keyboarding this on
to the cells in my body, are the result of slight imbalances in
electrically neutral matter due to the distribution of negative
(electron) and positive (proton) charges therein.
And how massive is
a single electron? Well, consider the electric field, the field
which measures the strength of interaction between electrons, of an
electron at rest relative to the observer. I won't write the
equation, except to note that it is similar to the gravitational
force equation above, only it is expressed in terms of the electric
charge instead of the mass. The force generated by this field causes
changes in kinetic energy of the particles which pass through it, and
so it is said to have a potential energy which balances the kinetic
energy changes. This potential energy can be summed to obtain an
overall energy density, and a total energy of the field. By a
surprising coincidence, the total energy of the field of a single
electron, is equal to the mass of the electron, multiplied by the
square of the speed of light.
Astonishingly, that
coincidence is not assumed to have any relevance to the Standard
Model as described next week.
1
In his column "Best of the Web Today" for
Friday 24 August 2012, James Taranto of the Wall
Street Journal paraphrases physics professor
Jerry Peterson of the University of Colorado at Boulder, discussing
changes in Colorado laws regarding concealed carry of firearms on
campus, as saying "…
he simply wants his students to feel safe to engage in discussions
that could become controversial―reiterated
that the presence of guns in his classroom 'would destroy the
learning environment.'" Taranto then asks, "What in the
world are they talking about that is so controversial it would lead
to gunfire in a physics
class?"
(http://online.wsj.com/article/SB10000872396390444358404577609343602510960.html)
I don't intend that this essay should be an answer to his question,
but you never know.
2 Expendables 2, where the alcoholic mercenary is stated to be a chemical engineer by training, with a corresponding level of scientific knowledge.
~~~
We'll continue the discussion in the following weeks. I can say, however, that he helped me immensely in writing the Displaced Detective series by verifying that my interpretation and implementation of M theory in those books was a legitimate one, thereby preparing me to write Extraction Point! with Travis S. Taylor. Jim has also helped me develop concepts for compact power supplies for the Displaced Detective series, but that hasn't been published...yet.
-Stephanie Osborn
