| 2011 | Particle Physics |
| 01 | p.1 | 21200 | An 'element' is what cannot be decomposed by chemistry |
| Full Idea: In the modern sense 'element' means a substance that cannot be decomposed by the methods of chemistry. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) |
| 01 | p.11 | 21201 | A 'field' is just a region to which points can be assigned in space and time |
| Full Idea: The word 'field' is simply a shorthand way of saying that a physical property is assigned to the points of space and time in a region. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) | |||
| A reaction: This is disappointing because I had begun to think that fields were foundational for modern ontology. Turns out they are operational abstractions (according to Martin). Note that a field extends over time. |
| 01 | p.13 | 21202 | The strong force has a considerably greater range than the weak force |
| Full Idea: The strong nuclear force has a range of 10^-15 m, considerably larger than the range of the weak force. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) | |||
| A reaction: This is because the bosons transmitting the weak force (W+, W-, W°) are much heavier than the gluons of the strong force. |
| 01 | p.14 | 21203 | Uncertainty allows very brief violations of energy conservation - even shorter with higher energies |
| Full Idea: The uncertainty principle states that energy conservation can be violated, but only for a limited period of time. As the energy violation increases, the time period within which 'borrowed' energy has to be 'paid back' decreases. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) | |||
| A reaction: This is the only reason modern physicists ever seem to mention the uncertainty principle. You can ask why this debt must be paid, but it seems to be hidden where the laws of physics may not even apply. |
| 01 | p.16 | 21204 | The standard model combines theories of strong interaction, and electromagnetic and weak interaction |
| Full Idea: As presently formulated, the standard model is two theories. One operates in the sector of strong interaction, and the other in the sector of the electromagnetic and weak interactions. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) | |||
| A reaction: The first is Quantum Chomodynamics (QCD). The second is Quantum Electrodynamics (QED). Interesting that the weak interaction is included in the latter, which (I take it) means there is an electro-weak union. Interactions are the heart of the model. |
| 01 | p.18 | 21205 | Many physicists believe particles have further structure, if only we could see it |
| Full Idea: Although standard particles are assumed to be structureless, many physicists believe that if distances could be probed down to 10^-35 m structures would be discovered. | |||
| From: Brian R. Martin (Particle Physics [2011], 01) | |||
| A reaction: Such probing is said to be probably impossible. And does the division then come to a halt? Aristotle's meditations on this are not irrelevant. |
| 02 | p.27 | 21206 | The properties of a particle are determined by its quantum numbers and its mass |
| Full Idea: In quantum theory, the full set of quantum numbers defines the state of the particle and, along with its mass, determines its properties. | |||
| From: Brian R. Martin (Particle Physics [2011], 02) |
| 02 | p.29 | 21208 | Eletrons don't literally 'spin', because they are point-like |
| Full Idea: The picture of a particle spinning like a top is sometime useful, but it is not consistent with the idea of the electron being point-like. In fact there is no analogy for spin in non-quantum physics. | |||
| From: Brian R. Martin (Particle Physics [2011], 02) | |||
| A reaction: If we take this stuff literally then it blow traditional metaphysics to bits, because an electron has properties without being a substance. In what sense can an electron 'have' properties if it is a point? In interactions they cease to be points. Eh? |
| 02 | p.29 | 21207 | The Exclusion Principle says no two fermions occupy the same state, with the same numbers |
| Full Idea: The 'exclusion principle' initially stated that no two electrons in a system could simultaneously occupy the same quantum state and thus have the same set of quantum numbers. The principle actually applies to all fermions, but not to bosons. | |||
| From: Brian R. Martin (Particle Physics [2011], 02) | |||
| A reaction: This principle is said to be at the root of atomic structure, making each element unique. What exactly is a 'system'? Why does this principle hold? How do you ensure two women don't wear the same dress at a party? |
| 06 | p.91 | 21209 | Electron emit and reabsorb photons, which create and reabsorb virtual electrons and positrons |
| Full Idea: In QED an electron constantly emits and reabsorbs virtual photons and these photons constantly create and reabsorb pairs of virtual electrons and positrons, and so on. | |||
| From: Brian R. Martin (Particle Physics [2011], 06) | |||
| A reaction: 'And so on'! These virtual particles have energy, and hence mass. |
| 06 | p.96 | 21210 | Virtual particles surround any charged particle |
| Full Idea: A cloud of virtual particles always surrounds a charged particle. | |||
| From: Brian R. Martin (Particle Physics [2011], 06) | |||
| A reaction: Here's a nice fact for aspiring Buddhists to meditate on. |
| 07 | p.103 | 21211 | If an expected reaction does not occur, that implies a conservation law |
| Full Idea: If some reaction is not observed when there is apparently nothing to prevent it occurring, it is an indication that a conservation law is in operation. | |||
| From: Brian R. Martin (Particle Physics [2011], 07) |
| 09 | p.148 | 21212 | The Higgs field, unlike others, has a nozero value in a state without particles |
| Full Idea: The Higgs field has the property of having a nonzero value in a state without particles, the vacuum state. Other fields are assumed to have a value zero in a vacuum state. | |||
| From: Brian R. Martin (Particle Physics [2011], 09) | |||
| A reaction: This seems to make a big difference to our concept of a field, since it has a measurable reality even when there are no particles. So it isn't just a geometrical frame for locating particles. |
| 10 | p.159 | 21213 | String theory only has one free parameter (tension) - unlike the standard model with 19 |
| Full Idea: Unlike the standard model, with its 19 free parameters (including the masses of quarks, coupling constants and mixing angles), string theories have a single free paramater: the string tension. | |||
| From: Brian R. Martin (Particle Physics [2011], 10) | |||
| A reaction: This must be one feature in favour of string theory, despite its problems. |