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| ==Explanation== | | ==Explanation== |
− | [[Cueball]] is acting here as someone teaching physics at a basic level, perhaps a high school science teacher. He seems to understand the general idea of the {{w|Fundamental interaction#Overview of the fundamental interaction|four fundamental forces}}, but his understanding gets progressively more sketchy about the details. The off-panel audience, probably a student or class, is interested, but quickly begins to realize Cueball's lack of understanding. Instead of acknowledging the problem directly, Cueball simply blusters onwards.
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− | The comic also outlines how progressively difficult it gets to describe the forces. {{w|Gravitation|Gravity}} was first mathematically characterized in 1686 as {{w|Newton's law of universal gravitation}}, which was considered an essentially complete account until the introduction of {{w|general relativity}} in 1915. The {{w|Electromagnetism|electromagnetic force}} does indeed give rise to {{w|Coulomb's law}} of {{w|electrostatics|electrostatic}} interaction (another {{w|inverse-square law}}, proposed in 1785), but a much more comprehensive description, covering full {{w|Classical electromagnetism|classical electrodynamics}}, was only given in {{w|Maxwell's equations}} around 1861. The {{w|strong interaction|strong}} and {{w|weak interaction|weak}} forces cannot easily be summarized as comparably simple mathematical equations. It's possible that Cueball does understand the strong and weak interactions, but is completely at a loss when he tries to summarize them.
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− | The strong force doesn't act directly between {{w|proton}}s and {{w|neutron}}s but between the {{w|quark}}s that form them. Unlike gravity and electromagnetism, the strong force {{w|Asymptotic freedom|gets stronger with increasing distance}}: It is ''loosely'' similar to the {{w|Hooke's law|restoring force of an extended spring}}. However, all stable heavy particles are neutral to the strong force, due to being made up of three "{{w|quantum chromodynamics|colors}}" (or a color and the appropriate "anticolor") of quarks. Between protons and neutrons there is a residual strong force, analogous in some ways to the {{w|van der Waals force}} between molecules. This residual strong force is carried by {{w|pion}}s and does decrease rapidly and exponentially with distance due to the pions having mass.
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− | The weak force is much weaker than electromagnetism at typical distances within an atomic nucleus (but is still stronger than gravity), and has a short range, so has very little effect as a ''force''. What it has instead is the property of changing one particle into another. It can cause a down quark to become an up quark, and in the process release a high-energy electron and electron anti-neutrino. This is known as {{w|beta decay}}, a form of radioactivity. Over even shorter distances, {{w|electroweak theory|and much higher temperatures}}, the weak interaction and electromagnetism are essentially the same, thus being merged to form the {{w|electroweak force}}. The electroweak force was also mentioned in a later comic, [[1956: Unification]].
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− | The title text touches upon a strange paradox regarding gravity: in isolation it is the simplest and easiest to understand of the four forces, with well-understood equations that can be taught to the layman with clear-cut examples (as it is the one force everyone experiences on a regular basis). However when taking other forces into account gravity turns out to be the {{w|Quantum_gravity|hardest to reconcile}} with a coherent (quantum) understanding of {{w|Theory of everything|all four forces together}}.
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| ==Transcript== | | ==Transcript== |
− | :[Cueball is holding his hands up while giving a lecture to an off panel audience.]
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− | :Cueball: There are four fundamental forces between particles:
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− | ::(1) '''''Gravity''''', which obeys this inverse square law:
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− | ::: F<sub>gravity</sub> = G m<sub>1</sub>m<sub>2</sub>/d<sup>2</sup>
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− | <!-- When math arrives, use the following:
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− | ::: <math>F_{gravity}=G\frac{m_1m_2}{d^2}</math> -->
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− | :Off panel audience: OK...
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− | :[Cueball is still holding his hands up while continues the lecture to the off panel audience.]
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− | :Cueball: (2) '''''Electromagnetism''''', which obeys ''this'' inverse-square law:
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− | :::F<sub>static</sub> = K<sub>e</sub> q<sub>1</sub>q<sub>2</sub>/d<sup>2</sup>
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− | <!-- When math arrives, use the following:
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− | ::: <math>F_{static}=K_e\frac{q_1q_2}{d^2}</math> -->
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− | ::...and also Maxwell's equations
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− | :Off panel audience: Also what?
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− | :[Zoom in on Cueball as he continues the lecture to the off panel audience.]
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− | :Cueball: (3) The '''''strong nuclear force''''', which obeys, uh ...
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− | :::...well, umm...
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− | ::...it holds protons and neutrons together.
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− | :Off panel audience: I see.
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− | :Cueball: It's strong.
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− | :[Cueball finishes the lecture to the off panel audience and spreads out his arm for the final remark.]
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− | :Cueball: And (4) the '''''weak force'''''. It [mumble mumble] radioactive decay [mumble mumble]
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− | :Off panel audience: That's not a sentence. You just said “Radio-
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− | :Cueball: – '''''And those are the four fundamental forces!'''''
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| {{comic discussion}} | | {{comic discussion}} |
− | [[Category:Comics featuring Cueball]]
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− | [[Category:Physics]]
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