Built on Facts

Classical vs. Modern Physics

Classical is how you look at it. To most people, classical music is whatever happens to be written before about 1900 that you hear played in orchestra halls and NPR. To classical fans, there’s more nuance involved. More ambiguity, too.

“Classical music” is generally divided into about four eras, one of which is itself confusingly called the “classical era”. They run as follows.

Baroque: From about 1600-1750. To pick a representative example of this beautiful and staggeringly diverse genre at random from playlist.com, here’s Bach’s Suite No. 3 In D – Air ‘On The G string’

Classical: 1750-1820. Guys like Mozart, writing things like this example of perfection: Symphony No. 40.

Romantic: 1820-1900. Dramatic and emotional, with some particularly noteworthy examples like Wagner’s Ride of the Valkyries.

Modern: Anything more recent than 1900. It’s all awful. Well, that’s a lie. But it is all totally nuts.

Physics is often divided into “classical physics” and “modern physics”. Where the line is varies wildly depending on who you ask. Here’s where I’ve seen the line put:

*Newton is classical, relativity and beyond is not. But then again the word “classical” is often used to mean quantum. So…
*Relativity is classical, quantum mechanics and beyond is not. But then again the entirely of regular quantum mechanics is called “semiclassical” because it quantizes the particles but not the fields. I’ve even seen the “semi” dropped on a few occasions.
*Quantum mechanics is classical, quantum field theory and beyond is not.

You could probably put the line in a few other places if you wanted. It really depends on context. Personally though if I had to set a hard and fast line I’d choose the first. Relativity was a truly paradigm-shattering concept and I think the Annus Mirabilis makes a nice bright line in the sand.


  1. #1 andy.s
    November 24, 2008

    How about: Modern is anything discussed in “Night Thoughts of a Classical Physicist” or “The Education of Henry Adams”.

  2. #2 Max Fagin
    November 24, 2008

    So I take it you are on of those classical music fans who stubbornly refuses to enjoy Aaron Copland just because he happened to be born in the wrong century?

  3. #3 Blaise Pascal
    November 24, 2008

    I tend to view the distinction between “modern” and “classical” physics as “discrete” versus “continuous”. Or, in simpler terms, if it uses h, it’s modern. Einstein is most famous for his work in classical physics, but he got his Nobel for his work in modern physics.

  4. #4 Chris P
    November 24, 2008

    Methinks you need to expand your horizons a little there is lots of great classical music post 1900. You just haven’t found it yet. Copland is a start and then there are several British composers too.

    Even though I am well over 50 I keep discovering new stuff that I like that I had never seen or heard of before. Discovery continues. Like finding out this weekend that there are several kinds of Morris dancing.

  5. #5 bwv
    November 24, 2008

    Words of wisdom from Uncle Milty:

    Advanced music, to the extent that it reflects the knowledge and originality of the informed composer, scarcely can be expected to appear more intelligible than these arts and sciences to the person whose musical education usually has been even less extensive than his background in other fields. But to this, a double standard is invoked, with the words music is music,” implying also that “music is just music.” Why not, then, equate the activities of the radio repairman with those of the theoretical physicist, on the basis of the dictum that “physics is physics.” It is not difficult to find statements like the following, from the New York Times of September 8, 1 957: “The scientific level of the conference is so high that there are in the world only 120 mathematicians specializing in the field who could contribute.” Specialized music on the other hand, far from signifying “height” of musical level, has been charged with “decadence,” even as evidence of an insidious “conspiracy.”

  6. #6 Uncle Al
    November 24, 2008

    If h = 0 it is classical physics. Newton mathematized all physics then known, but EM came later. Einstein mathematized all physics then known, but h = h came later.

    Classical physics can be falsified. Postulated isotropic vacuum can fail (teleparallelism) for angular momentum: physically spinning bodies, quantized momenta (particle and orbital as magnets), relativisitic spin-orbit coupling, geometric chirality. PSR J1903+0327 (arxiv/0805.2396) strong field kills all of them but geometric chirality (nonsuperposability with mirror image).

    Parity is chirality in all directions. Covariance with respect to reflection in space and time is not required by the Poincar group of Special Relativity or the Einstein group of General Relativity. Geometric parity of mass configuration is a huge loophole!

    An observed chiral anisotropic vacuum background, through Noether’s theorem, unrequires conservation of angular momentum. Single crystal quartz test masses in space groups P3(1)21 and P3(2)21 are the opposite shoes compared in a parity Eotvos experiment. Somebody should look.

  7. #7 Chris
    November 24, 2008

    Nutty music is some of my favorite music.

  8. #8 Eric Lund
    November 24, 2008

    I agree with the other posters who say you’re missing out on a lot of good post-1900 classical music. If you happen not to like twelve-tone music, that’s fine; I don’t either. If you’re not into John Cage, I’m fine with that, too; much of his work is meta-music rather than music. But there are quite a few good composers from the 20th century: Copland, Holst, Gershwin, Grainger, Britten, Vaughan Williams, and Milhaud, to name a few.

    As for the topic at hand: I would say that classical physics involves not only the h -> 0 limit but the weak gravity limit as well. Whether to include special relativity as classical physics is open to debate (if not, then add v << c to the above list of limits). Essentially all of plasma physics has been done in the last hundred years, but it's entirely classical.

  9. #9 Eric Lund
    November 24, 2008

    Oops, some of my post got cut off there. That should be:

    …add v << c to the above list of limits).

    I’m in plasma physics, which is 100% classical even though the field did not exist before the early 20th century.

  10. #10 CCPhysicist
    November 24, 2008

    I’m glad to see someone beat me to the comment about Copeland. I would add Bernstein. Our local symphony does not avoid the modern era, and there is quite a bit of outstanding music that should be played more than it is. Think Modern Jazz Quartet for symphony orchestra. It is not all atonal post-modern noise. I’d also observe that if you have never heard the Firebird done live, your judgement is sort of like forming an opinion of rock without having heard a rock band live. Recordings cannot do justice to sound that can blow you out of your seat.

    The physics question is an interesting one. IMHO, there is nothing “classical” about “classical QM” or even “classical stat mech”, since neither was accepted until well into the 20th century. I draw the line between Maxwell’s E&M and the Maxwell-Boltzman theory. The former was confirmed by Hertz in the 19th century; the latter was not really accepted until the atom became real circa 1911 (plus Einstein’s questionable brownian motion paper in 1905).

    Classical physics is that of rigid bodies moving non-relativistically and non-rigid bodies (such as springs and fluids) treated as a single compressible or stretchable substance, something like clay or jello, with phenomenological values for key properties rather than a collection of molecules interacting electromagnetically. It also includes all of the non-quantum properties of circuits and optics.

  11. #11 Frederick Ross
    November 24, 2008

    “Classical mechanics” refers to nonrelativistic mechanics of point particles and extended (possibly elastic) objects. “Classical” applied to some piece of physics generally means h -> 0 (as someone mentioned already). There just aren’t enough words to go around, so they get reused.

    And you’ve forgotten the treasury of early music we have stretching back more or less to the 9th century. English song and England’s viol consort music in the 17th century, for instance, is still considered Renaissance, not Baroque, but constituted two of the greatest moments on western music.

    And again, you’re missing out on all kinds of great 20th century stuff. In addition to the folks people have already mentioned, Anton Webern (despite being serialist) wrote some of the most deeply expressive music I know. Stravinsky, Poulenc, Meredith Monk, Olivier Messiaen, just start poking around.

    There are more good composers working today than at any previous time in history. They don’t make nice background music the way Mozart does (if you want to know how many people are listening to Mozart as anything but background noise, see how many people are laughing in the fourth movement of Symphony No. 41 — they’re the ones that get it).

  12. #12 Bob Sykes
    November 24, 2008

    Your art critics are wrong and you are right. Everything from 1900 on in “classical” music, opera, ballet, painting, poetry, literature, sculpture, architecture is crap and criminal fraud. It you destroyed the entire “artistic” output of the 20th Century, the world would be a measurably better place.

    Even todays popular arts are bad. Jazz died a richly earned death in the 1950s. “Artistes” like Davis are charlatans. Rap is crap. Even Rock & Roll died in the early 1960s.

  13. #13 Carl Brannen
    November 25, 2008

    I’ve been thinking “somdeay” of writing a post on the subject of “quantum numbers” and the different (classical) frequencies you can get from various modes of vibration on a drum head. This is along the line of what you are doing here and if you write one you’ll save me the effort.

    Here’s a good start from the classical side. Of course drums are not quantum, but the difference in the math is fairly small, and the classical differential equations give a nice series of states similar to the differential equations of quantum mechanics.

  14. #14 ropty
    November 25, 2008

    For what it is worth, classical music in the 20th century is divided into two. From about 1900 to WWII is “modern” music (Stravinsky, Scheonberg, Bartok) and music since the war is “Contemporary” music (Boulez, Carter, Cage, and others in a long list).

    No doubt, there is another break somewhere in the late 90s, or early 2000s. I have not heard any widely accepted word to describe it.

  15. #15 Bob Hawkins
    November 25, 2008

    Let me add Andrzej Panufnik to the list of post-1900 composers worth the listening.

    I consider relativity the final release version of classical physics. QM circa 1927 was version 0.1 of postclassical physics. We’re up to about version 0.6 with quantum field theory.

  16. #16 Cyrus Robinson
    November 25, 2008

    So, the “totally nuts” music said I didn’t have permission to access the file. 🙁

  17. #17 Marc
    November 25, 2008

    To Bob Skyes:

    Everything you said was 100% incorrect because of this simple reason:

    Music is completely subjective.

    Your opinion and the opinion of a bunch of elitists doesn’t change that.

  18. #18 Chris Coon
    November 25, 2008

    Music can only be called advanced within a certain societal framework. This is self-evident by the proliferation of different music styles around the world–it is an inherently human-created and enjoyed phenomenon, with no particular sort of truth behind it. Science and math describe, within the best of our ability, a truth beyond human culture, therefore, it is not appropriate to compare a math conference to a musical conference.

    In essence, one of these things would matter to a non-human entity, and the other would not, which, as a musician myself, is something with which I have had to come to terms. Spending so much free time developing a music that nearly no one can appreciate is decadent, though more power to anyone who can get away with it.

  19. #19 llewelly
    November 25, 2008

    Your links to Wagner’s Valkyries gets a ‘hometown has been shutdown’ page and the modern classical whatever it was returns Error 403: Forbidden.

  20. #20 llewelly
    November 25, 2008

    PS. How can a science fiction fan not like Gustav Holst? That’s like a Tolkien fan not liking elves.

  21. #21 Paul Murray
    November 25, 2008

    Modern music is anything after the Beatles. If it has a synth or relies on electronic effects, it’s modern.

  22. #22 Martin Regnen
    November 26, 2008

    Your links to Wagner’s Valkyries gets a ‘hometown has been shutdown’ page and the modern classical whatever it was returns Error 403: Forbidden.

    Shutting down anything that plays Wagner and forbidding modern “serious art music” are both excellent ideas.

  23. #23 Rettaw
    November 29, 2008

    One of my teachers had the most pragmatic definition I’ve seen yet.

    Anything older than him is classical.

  24. #24 cfcasper
    December 10, 2008

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