Transcript
6 – Standard Model
A few introductory words of explanation about this transcript.
This transcript includes the words sent to the narrator for inclusion in the latest
version of the associated video. Occasionally, the narrator changes a few words
on the fly in order to improve the flow. It is written in a manner that suggests to
the narrator where emphasis and pauses might go, so it is not intended to be
grammatically correct.
The Scene numbers are left in this transcript although they are not necessarily
observable by watching the video.
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might be useful corollary information.
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that time.
103 – Avatar Intro
CHAUCER: OK, you two, Let’s go back to the birth of the universe, things are
HOT – REAL HOT. And things are happening FAST -- REAL FAST.
105 – Hot Big Bang
For the tinniest increment of time that it is possible to talk about...10-43 seconds,
the temperature was 1032 degrees, and the density downright indescribable.
At that instant, there was only one universal force and one type of elementary
particle… But it wouldn’t last. At the end of this instant, Gravity separates itself
from the union.
At 10-35 seconds, the strong nuclear force exits the union as well, and this
triggers inflation – the event where the universe instantaneously grew in size
from tinier than an atom to an unknown large size.
This expansion and subsequent cooling down to 1027 degrees allows six different
types of quarks to form.
At 10-12 seconds, and 1015 degrees, the Weak force and Electromagnetism
separate and we have the four independent forces we know today. At this point
all six types of leptons have formed including the electron.
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At 10-6 seconds, up and down quarks have formed protons and neutrons. All
heavy quarks have decayed, all heavy leptons have decayed, all anti-matter has
disappeared.
And by the time the universe is only one second old, protons and neutrons are
already getting together to form the lightest atomic nuclei.
110 – AvatarInterlude1
DIANA: Wait! Can you slow down and try that again?
CHAUCER: Sure, Diana, can you tell me the difference between force and
matter?
DIANA: Well sure… Matter is “stuff” that you can hold in your hand or at least
visualize holding in your hand, and a force is something that causes matter to
move, change, or react – an action.
Air is matter even though you cannot see it unless you are in Los Angeles.
CHAUCER: Pretty good. Now consider a piece of matter, and imagine taking it
apart down to its basic constituents – the particles that make it up. Down to the
atoms ..and further down to the protons, neutrons… and finally to the quarks and
electrons. If our hands were small enough, we could hold them in our hands as
well. So these particles pass your “hold-it-in-your-hand” matter test and are
declared matter…. But at this level of tiny, things get a little fuzzy…watch this
115 – DownToSmall
As we take matter apart down to the smallest scales, we must pass through
levels of structure that are only possible because of FORCES that hold these
structures together. The proton and electron for example are attracted to each
other …and that force of attraction is what holds them together in the atom. But
what is it really that causes this attraction. How does the electron know the
proton is there and what draws it towards the proton? How does the electron
know NOT to be attracted to the neutron ?
The answer is that the electron and the proton each fill the space around them
with countless millions of other tiny particles that have only the most ephemeral
existence. Because it is electrically neutral, the neutron does not.
These particles come into existence only briefly and are gone …only to be
replaced by another one thrown out by the parent particle. On this scale, the tiny
bit of energy that is needed for their existence can be created out of
…NOTHING. But they also MUST DISAPPEAR in the briefest instant because
the energy used to create them can only exist for a very brief instant.
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You can imagine these virtual particles as balls tethered to the parent particle by
a rubber band and snapping back to the parent when they disappear. If one or
more of them should encroach upon the territory of virtual particles tethered to
another parent particle, they can get entwined and exchanged. Such an
exchange is felt by the parent particles as a force.
118 – Avatar Interlude2
CHAUCER:
These FIELDS of virtual particles surrounding a parent particle are created in
very specific patterns and fill the surrounding space in a well defined way and
scientists cleverly call them …FIELDS. The virtual particles are called carriers or
mediators of FORCE.
120 – FourForces
Scientists recognize four distinct kinds of force fields, and they all work through
the mechanism described above. You are readily familiar with two of these
forces. Gravity and Electromagnetism operate on a scale that we encounter in
our everyday life.
A third force causes quarks to stick together in protons and neutrons and a
residuum of this force causes protons and neutrons to stick together in the
nucleus of atoms. This force is called the Strong Force or sometimes the Color
Force.
The fourth force causes radioactivity and is called the Weak Force.
125 –PhotonGraviton
The virtual particles that make up these fields and that get exchanged in each
force are called gauge bosons. And each of the four forces has its own gauge
bosons.
Within limitations, energy and mass can be created out of the nothingness of
space-time, but only for a very brief instant. And the more energy and mass
these virtual particles have, the shorter must be the time that they can exist
before snapping back to the parent.
Lighter gauge bosons can exist for a longer time and these in turn can get farther
from the parent before they must return. So the RANGE of a force is directly
related to the mass of it’s gauge bosons.
The photon is the gauge boson for the Electromagnetic force and the graviton is
the gauge particle for gravity. Both of these particles are massless and so the
range of these two forces is unlimited.
130 –QCDandWeak
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The Strong Force is much more complex. The charge-property responsible for
the force between quarks comes in three distinct states…not just two like the
positive and negative charge states in electromagnetism.
So in a loose analogy to the three primary colors…red, green and blue, the three
kinds of charges in the strong force are usually referred to as "color charge" and
are designated red, green and blue.
Since the theory of electric charge is dubbed Quantum Electrodynamics or QED,
the name for quark theory has become "Quantum Chromodynamics" or QCD.
It is interesting to note that all observed particles are “white” –color is never
visible—and since the proton and its baryon cousins each have three quarks –
the colors possessed by the three quarks MUST be one each of red, green, and
blue which sum to white. And mesons are always a quark and antiquark pair
containing colors of red-antired, or blue-antiblue or green-antigreen …also
combinations that equal “white”.
The Strong Force of course must have its own gauge boson, and it turns out that
there are 8 of them – 8 different gluons that carry the color force. And unlike the
other force carriers, gluons have a color property themselves and therefore
interact with each other. Every time two quarks interact and exchange a gluon –
they swap colors.
Also because gluons are attracted to each other, it is possible to have a gluon
collection which is referred to as … what else…a glueball.
The interactions that result from the Weak Force are incredibly shortranging…they are effective over a distance even smaller than a proton’s
diameter…and this accurately implies that the weak force gauge particles (called
the W and the Z) are immensely heavy.
Over distances small enough and at really really high energies, the four forces
are indistinguishable because their respective force particles are also
indistinguishable.
135 –UnifyForces
The Standard Model of Physics combines QCD with QED and the Weak Force
theory. It states that there are 6 quarks and 6 leptons, and 12 gauge bosons (as
well as their antiparticles). But only the up and down quarks, the electron and
the lightest neutrino are populous today.
In the Standard Model, the entire system of matter and forces (except gravity) is
encapsulated in a few simple equations and is organized around one core
principle known as local gauge symmetry -- Amazing.
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203 – AvatarEnd
DIANA: OK, now do you want to tell me what you told me before I told you to tell
me slower?
CHAUCER: SURE! Let’s go back to the birth of the universe, things are HOT –
REAL HOT. And things are happening FAST -- REAL FAST.
205 – HotEnd
For the tinniest increment of time that it is possible to talk about...10-43 seconds,
the temperature was 1032 degrees, and the density downright indescribable.
At that instant, there was only one universal force and one type of elementary
particle… But it wouldn’t last. At the end of this instant, Gravity separates itself
from the union.
At 10-35 seconds, the strong nuclear force exits the union as well, and this
triggers inflation – the event where the universe instantaneously grew in size
from tinier than an atom to an unknown large size.
This expansion and subsequent cooling down to 1027 degrees allows six different
types of quarks to form.
At 10-12 seconds, and 1015 degrees, the Weak force and Electromagnetism
separate and we have the four independent forces we know today. At this point
all six types of leptons have formed including the electron.
At 10-6 seconds, up and down quarks have formed protons and neutrons. All
heavy quarks have decayed, all heavy leptons have decayed, all anti-matter has
disappeared.
And by the time the universe is only one second old, protons and neutrons are
already getting together to form the lightest atomic nuclei.
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