Category Archives: Physics

November 27, 2021

Entropy 101

Entropy is a big topic, both in science and in the popular gestalt. I wrote about it in one of my very first blog posts here, back in 2011. I’ve written about it a number of other times since. Yet, despite mentioning it in posts and comments, I’ve never laid out the CD collection analogy from that 2011 post in full detail.

Recent discussions suggest I should. When I mentioned entropy in a post most recently, I made the observation that its definition has itself suffered entropy. It has become more diffuse. There are many views of what entropy means, and some, I feel, get away from the fundamentals.

The CD collection analogy, though, focuses on only the fundamentals.

31 Comments | tags: entropy | posted in Physics

September 17, 2021

Wilczek: Fundamentals

By Wyrd Smythe

I just finished Fundamentals: Ten Keys to Reality (2021), by Frank Wilczek. It’s yet another book explaining fundamental physics for lay readers, and it does so pretty much entirely within the bounds of mainstream science. I enjoyed reading it, but it’s mainly a review of physics as we know it.

I saw it on the library’s list of new books and put it on hold back on May 14th. It didn’t become available until September 3 — more than a three-month wait. Apparently lots of people wanted to read it.

Bottom line, I recommend it as an easy and enjoyable read, especially for those with a more casual interest in physics.

21 Comments | tags: Frank Wilczek, Heisenberg Uncertainty, Isaac Newton | posted in Books, Physics

September 8, 2021

Smolin: Time Reborn

By Wyrd Smythe

I’ve been reading science texts almost as long as I’ve been reading anything. Over those years, many scientists and science writers have taught me much of what I know about science. (Except for a Computer Science minor, and general science classes, most of my formal education was in the Liberal Arts.)

Recently I read Time Reborn (2013), by Lee Smolin, a theoretical physicist whose personality and books I’ve enjoyed. I don’t always agree with his ideas, but I’ve found I do tend to agree with his approaches to, and overall sense of, physics.

However in this case I almost feel Smolin, after long and due consideration, has come around to my way of thinking!

24 Comments | tags: arrow of time, is time fundamental, Lee Smolin, spacetime, time | posted in Books, Physics

August 27, 2021

BB #75: Gloves and Shoes

By Wyrd Smythe

Speaking of Bell tests, I’ve noticed that science writers often struggle to find a good metaphor that illustrates just what’s so weird about the correlation between entangled particles. Bell tests are complex, and because they squat in the middle of quantum weirdness, they’re hard to explain in any classical terms.

I thought I had the beginnings of a good metaphor, at least the classical part. But the quantum part is definitely a challenge. (All the more so because I’m still not entirely clear on the deep details of Bell’s theorem myself.)

Worse, I think my metaphor fails the ping-pong ball test.

35 Comments | tags: Bell's Theorem, particles, quantum mechanics | posted in Brain Bubble, Physics

August 26, 2021

QM 101: Fun with Photons

By Wyrd Smythe

Last time I explored the quantum spin of photons, which manifests as the polarization of light. (Note that all forms of light can be polarized. That includes radio waves, microwaves, IR, UV, x-rays, and gamma rays. Spin — polarization — is a fundamental property of photons.)

I left off with some simple experiments that demonstrated the basic behavior of polarized light. They were simple enough to be done at home with pairs of sunglasses, yet they demonstrate the counter-intuitive nature of quantum mechanics.

Here I’ll dig more into those and other experiments.

10 Comments | tags: Bell's Theorem, photons, QM101, quantum mechanics | posted in Physics

August 25, 2021

QM 101: Photon Spin

By Wyrd Smythe

Earlier in this QM-101 series I posted about quantum spin. That post looked at spin 1/2 particles, such as electrons (and silver atoms). This post looks at spin in photons, which are spin 1 particles. (Bell tests have used both spin types.) In photons, spin manifests as polarization.

Photon spin connects the Bloch sphere to the Poincaré sphere — an optics version designed to represent different polarization states. Both involve a two-state system (a qubit) where system state is a superposition of two basis states.

Incidentally, photon polarization reflects light’s wave-particle duality.

8 Comments | tags: Bell's Theorem, photons, QM101, quantum spin, wave-function, wave-particle duality | posted in Physics

August 19, 2021

BB #74: Which MWI?

By Wyrd Smythe

I finished The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality (2017), by Paul Halpern. As the title implies, the book revolves around the careers and lives of John A. Wheeler (1911–2008) and Richard Feynman (1918–1988). After Feynman graduated from MIT he became Wheeler’s teaching assistant at Princeton. The two men, despite very different personalities, became life-long friends and collaborators.

One of Wheeler’s many claims to fame is his promotion of Hugh Everett’s PhD thesis, The Theory of the Universal Wave Function. That paper, of course, is the seed from which grew the Many Worlds Interpretation of Quantum Mechanics.

The thing is, there are two major versions of the MWI.

3 Comments | tags: Many Worlds Interpretation, MWI, Paul Halpern, quantum mechanics, Sabine Hossenfelder | posted in Brain Bubble, Physics

August 13, 2021

BB #73: Wavefunction Collapse

By Wyrd Smythe

I’m two-thirds through my second Paul Halpern book this month. Earlier I read his book about cosmology, Edge of the Universe: A Voyage to the Cosmic Horizon and Beyond (2012), which was okay. Now I’m reading The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality (2017), which I’m enjoying a bit more. In part because cosmology has changed more since 2012 than quantum physics has since 2017. (Arguably, the latter hasn’t changed much since the 1960s.)

I wrote about Halpern’s book, Einstein’s Dice and Schrödinger’s Cat (2015), last year. As the title implies, it focuses on two great names from physics. Quantum Labyrinth (as its title also implies) also focuses on two great physics names.

But today’s Brain Bubble (as the title implies) is about wavefunction collapse.

10 Comments | tags: Paul Halpern, quantum mechanics, Schrödinger Equation, wave-function | posted in Brain Bubble, Physics

July 9, 2021

MWI: Questions, part 3

By Wyrd Smythe

This is the third part of a series examining the Many Worlds Interpretation of Quantum Mechanics (the MWI of QM). The popularity of the MWI in books, blogs, and science videos, especially among the science-minded, tends to keep in present in some corner of my mind. Blog posts are a way to shoo it out.

The first part introduced the topic and talked about cats. The second part discussed the Schrödinger equation, wavefunctions, decoherence, and the question of how multiple instances of matter can coincide. That question, to me, is a central issue I have with MWI.

This time I dig into quantum superposition and touch on a few other topics.

14 Comments | tags: Many Worlds Interpretation, MWI, Schrödinger Equation, wave-function | posted in Physics

July 8, 2021

MWI: Questions, part 2

By Wyrd Smythe

Last time I started exploring questions I have about the Many Worlds Interpretation of Quantum Mechanics (the MWI of QM). Obviously I’m not a fan; quite the opposite. It presents as parsimonious, hung on the single hook of a universal wavefunction, but I think it gets more complicated and cumbersome when examined. I can’t say it’s broken, but I don’t find it very attractive.

I suspect most people, even in physics, don’t care. A few have invested themselves in books or papers, but these interpretations don’t matter to real physics work. The math is the math. But among the philosophical, especially the ontological, it’s food for debate.

Being both philosophical and ontological, I do smell what’s cooking!

13 Comments | tags: Many Worlds Interpretation, MWI, Schrödinger Equation, wave-function | posted in Physics