Particle Physics

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(Smbc, second one here. There were a lot of relevant ones to choose from – this one also seems ‘relevant’. And this one. And this one. This one? This one? This one? Maybe this one? In the end I decided to only include the two comics displayed above, but you should be aware of the others…)

The book is a bit dated, it was published before the LHC even started operations. But it’s a decent read. I can’t say I liked it as much as I liked the other books in the series which I recently covered, on galaxies and the laws of thermodynamics, mostly because this book was a bit more pop-science-y than those books, and so the level of coverage was at times a little bit disappointing compared to the level of coverage provided in the aforementioned books throughout their coverage – but that said the book is far from terrible, I learned a lot, and I can imagine the author faced a very difficult task.

Below I have added a few observations from the book and some links to articles about some key concepts and things mentioned/covered in the book.

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“[T]oday we view the collisions between high-energy particles as a means of studying the phenomena that ruled when the universe was newly born. We can study how matter was created and discover what varieties there were. From this we can construct the story of how the material universe has developed from that original hot cauldron to the cool conditions here on Earth today, where matter is made from electrons, without need for muons and taus, and where the seeds of atomic nuclei are just the up and down quarks, without need for strange or charming stuff.

In very broad terms, this is the story of what has happened. The matter that was born in the hot Big Bang consisted of quarks and particles like the electron. As concerns the quarks, the strange, charm, bottom, and top varieties are highly unstable, and died out within a fraction of a second, the weak force converting them into their more stable progeny, the up and down varieties which survive within us today. A similar story took place for the electron and its heavier versions, the muon and tau. This latter pair are also unstable and died out, courtesy of the weak force, leaving the electron as survivor. In the process of these decays, lots of neutrinos and electromagnetic radiation were also produced, which continue to swarm throughout the universe some 14 billion years later.

The up and down quarks and the electrons were the survivors while the universe was still very young and hot. As it cooled, the quarks were stuck to one another, forming protons and neutrons. The mutual gravitational attraction among these particles gathered them into large clouds that were primaeval stars. As they bumped into one another in the heart of these stars, the protons and neutrons built up the seeds of heavier elements. Some stars became unstable and exploded, ejecting these atomic nuclei into space, where they trapped electrons to form atoms of matter as we know it. […] What we can now do in experiments is in effect reverse the process and observe matter change back into its original primaeval forms.”

“A fully grown human is a bit less than two metres tall. […] to set the scale I will take humans to be about 1 metre in ‘order of magnitude’ […yet another smbc comic springs to mind here…] […] Then, going to the large scales of astronomy, we have the radius of the Earth, some 10⁷ m […]; that of the Sun is 10⁹ m; our orbit around the Sun is 10¹¹ m […] note that the relative sizes of the Earth, Sun, and our orbit are factors of about 100. […] Whereas the atom is typically 10^–10 m across, its central nucleus measures only about 10^–14 to 10^–15 m. So beware the oft-quoted analogy that atoms are like miniature solar systems with the ‘planetary electrons’ encircling the ‘nuclear sun’. The real solar system has a factor 1/100 between our orbit and the size of the central Sun; the atom is far emptier, with 1/10,000 as the corresponding ratio between the extent of its central nucleus and the radius of the atom. And this emptiness continues. Individual protons and neutrons are about 10^–15 m in diameter […] the relative size of quark to proton is some 1/10,000 (at most!). The same is true for the ‘planetary’ electron relative to the proton ‘sun’: 1/10,000 rather than the ‘mere’ 1/100 of the real solar system. So the world within the atom is incredibly empty.”

“Our inability to see atoms has to do with the fact that light acts like a wave and waves do not scatter easily from small objects. To see a thing, the wavelength of the beam must be smaller than that thing is. Therefore, to see molecules or atoms needs illuminations whose wavelengths are similar to or smaller than them. Light waves, like those our eyes are sensitive to, have wavelength about 10^–7 m […]. This is still a thousand times bigger than the size of an atom. […] To have any chance of seeing molecules and atoms we need light with wavelengths much shorter than these. [And so we move into the world of X-ray crystallography and particle accelerators] […] To probe deep within atoms we need a source of very short wavelength. […] the technique is to use the basic particles […], such as electrons and protons, and speed them in electric fields. The higher their speed, the greater their energy and momentum and the shorter their associated wavelength. So beams of high-energy particles can resolve things as small as atoms.”

“About 400 billion neutrinos from the Sun pass through each one of us each second.”

“For a century beams of particles have been used to reveal the inner structure of atoms. These have progressed from naturally occurring alpha and beta particles, courtesy of natural radioactivity, through cosmic rays to intense beams of electrons, protons, and other particles at modern accelerators. […] Different particles probe matter in complementary ways. It has been by combining the information from [the] various approaches that our present rich picture has emerged. […] It was the desire to replicate the cosmic rays under controlled conditions that led to modern high-energy physics at accelerators. […] Electrically charged particles are accelerated by electric forces. Apply enough electric force to an electron, say, and it will go faster and faster in a straight line […] Under the influence of a magnetic field, the path of a charged particle will curve. By using electric fields to speed them, and magnetic fields to bend their trajectory, we can steer particles round circles over and over again. This is the basic idea behind huge rings, such as the 27-km-long accelerator at CERN in Geneva. […] our ability to learn about the origins and nature of matter have depended upon advances on two fronts: the construction of ever more powerful accelerators, and the development of sophisticated means of recording the collisions.”

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Matter.
Particle.
Particle physics.
Strong interaction.
Weak interaction (‘good article’).
Electron (featured).
Quark (featured).
Fundamental interactions.
Electronvolt.
Electromagnetic spectrum.
Cathode ray.
Alpha particle.
Cloud chamber.
Atomic spectroscopy.
Ionization.
Resonance (particle physics).
Spin (physics).
Beta decay.
Neutrino.
Neutrino astronomy.
Antiparticle.
Baryon/meson.
Pion.
Particle accelerator/Cyclotron/Synchrotron/Linear particle accelerator.
Collider.
B-factory.
Particle detector.
Cherenkov radiation.
Sudbury Neutrino Observatory.
Quantum chromodynamics.
Color charge.
Force carrier.
W and Z bosons.
Electroweak interaction (/theory).
Exotic matter.
Strangeness.
Strange quark.
Charm (quantum number).
Antimatter.
Inverse beta decay.
Dark matter.
Standard model.
Supersymmetry.
Higgs boson.
Quark–gluon plasma.
CP violation.