Wednesday, January 10, 2018

The 4 Cs of Physics

Sabrine Hossenfelder has a post about why physics is not about beauty although many physicists may think so

And I can’t blame them. Because nothing else is happening on this planet. There’s just me and my attempt to convince physicists that beauty isn’t truth.
Nature has no obligation to be pretty, that much is sure. But the truth seems hard to swallow. “Certainly she doesn’t mean that,” they say. Or “She doesn’t know what she’s doing.” Then they explain things to me. Because surely I didn’t mean to say that much of what goes on in the foundations of physics these days is a waste of time, did I? And even if, could I please not do this publicly, because some people have to earn a living from it.
Now Eli does not disagree with this, nor with the Capitalist Imperialist Pig who is on a Greek Philosopher Beauty and Truth kick, but Eli does want to engage with a challenge that the Pig threw down at Back Reaction
Beauty may be an unreliable heuristic, but the challenge for the doubter is to come up with something better - I mean something that works.
This was not well received by the host
I also don't know why you or CIP or anyone else thinks it's my task to come up with something to replace criteria from beauty. I am pointing out using them is bad scientific practice, and that's that. If people who use them cannot come up with anything better, maybe they shouldn't be scientists. I don't know why I should give them something else to do.
 Eli suggested something else and the Bunny would like to discuss it here, especially as his responses appear to have issues getting through there besides which he could use the hits and values the occasional intelligent comment.

It ties back to discussions ongoing where science is under attack, the existence of a consensus and why such a consensus exists.  The sorely missed Andy Skuce had a nice post and Michael Tobis has always skillfully parsed that problem. Eli has also played in the sandbox, most recently pointing out that the consensus is created by a coherent and consilient set of models or three Cs

By this is meant that the theory does not contradict itself, that it explains a great deal, both of the observations as well as extending beyond the immediate issue under consideration.  To this Eli wants to add another C, concise.

Especially for physics, concise takes the place of beauty.  Valued physics theories are concise, they may not necessarily be simple, in the spirit of Einstein's
It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.
After all, ask mom or dad what a LaPlace operator or a Hamiltonian is (no coaching and no moms or dads who are professors of physics), but concise is a good description, terse also, but terse starts with a t.

Engineering does not much like concise, it is much more concerned with precise.  The value of everything is important, the meaning less so or sometimes not at all.  Computers have made this tendency worse.  Chemistry is, with difficulty moving from moleculat engineering to first principles.  Computers have enabled this  Climate science from stamp collecting to calculation with complex models. 

Physics values precision as a secondary issue, but it is focused on understanding and understanding requires a small number of general principles from which precision flows with added complication. 

So truth is not beauty, but it is a creature of a few symbols and a modicum of words explaining much.


CapitalistImperialistPig said...

What is the nature of beauty is one of those tough questions, of course, but to me, at least, coherence, concision, and consilience are key elements. Almost every definition of beauty would include harmony or coherence. Concision is a form of simplicity, another element. Finally consilience, or bringing together apparently disparate phenomena is a key index of the greatest theories, reminding me of Bacon's dictum that "there is no thing of excellent beauty that hath not some strangeness in the proportion."

Anonymous said...

The doctrine according to Zappa...

Information is not knowledge
Knowledge is not wisdom
Wisdom is not truth
Truth is not beauty
Beauty is not love
Love is not music
Music is the best!

Johnny Vector said...

I agree with izenmeme. After all, wisdom is the domain of the wiz, which is extinct. And beauty is a French phonetic corruption of a short cloth neck ornament, currently in resurgence.

Anonymous said...

Simplicity in a scientific theory is not just heuristic, but useful. In general, the simplest theories tend to be the most predictive.

For statistical models, this can actually be proved mathematically, giving rise to metrics like the Akaike Information Criterion.

The problem is that for more complex theories, consensus, consilience and even conciseness are hard to measure objectively.

Dirac was a big advocate of "beauty" as a criterion for judging a theory. Humor has also been mooted. Pauli used to always ask, "Where's the joke?" when he wanted to get to the point and make sense of a subject. Indeed, the insight that comes when a theory dawns on you and makes sense is very like that we experience when we "get" a joke.

CapitalistImperialistPig said...

@JV - I think that the actual etymology is from the PIE *deu, meaning, among other things, to do.

Fernando Leanme said...

What do you mean engineering doesn't value concise, but values precise? I'm really lost, but I became a supervisor of engineers and scientists many years ago, so I may be more focused on their ability to write a report I can read when I'm taking a bath or waiting to board a plane.

EliRabett said...

Ah yes, the engineering level report that Steve McIntyre wants but can't describe. Start here for some classic giggles

Fernando Leanme said...

This is closer to the engineering report format I like.

The last large report I supervised went in a three ring binder with a few fold out pages. It was a feasibility study for building something. Since then I've consulted and I mostly review others' reports and write critiques and suggest improvements. And I'm still a bit confused regarding what you think engineering reports are supposed to be like.

EliRabett said...

Talk to Steve @ClimateAudit

dave said...

At school, we had to learn something of the 1819 poem by Keats, "Ode on a Grecian Urn". Which has the Memorable Lines:
" 'Beauty is truth, truth beauty,' – that is all
Ye know on earth, and all ye need to know"

Which struck me as being rather dubious. Many years later, I read of Charles Darwin's 1856 letter to J. D. Hooker:
"What a book a Devil’s chaplain might write on the clumsy, wasteful, blundering low & horridly cruel works of nature!"

Darwin worked hard at consilience, explaining all related facts regardless of beauty. Good call by Zappa.

Jeffrey Davis said...

Beauty is our consolation prize because Death.