Of Particular Significance

How Einstein Trumped Newton

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/16/2012

Sometimes I encounter people whose impression is that what Einstein’s 1905 theory of special relativity (the one that said no object’s speed can exceed the speed of light in vacuum, etc.) did in “overthrowing” the ideas of the past was somehow like what the Bolsheviks did to the Czars twelve years later– out with the old order, in with the new, and let nothing remain behind.  The widespread notion, inherited from philosopher and historian Thomas Kuhn, is that a new paradigm arose, and the old was swept away.  The truth is far different.  Important parts of the conceptual superstructure of 19th century physics had to be replaced, but the predictive mathematical core was not replaced, but rather was extended.   It was like tearing the roof and facade off a building while keeping the interior beams and columns, then extending the structure to make it much larger than before, and finally giving it a very novel external appearance.  That’s why the Einsteinian revolution was possible at all! Newton’s equations had already been used to design all sorts of real-world 18th and 19th century technology.  If Einstein’s equations hadn’t contained those of Newton and his descendants as a special case, they would have been in conflict with the real world… a no-no for a scientific theory.

Sine this is so important to understand, I’ve written an article illustrating how Einstein’s equations relating energy, momentum, mass and speed were an extension, not a replacement, of the equations that were previously in use.   It describes how Einstein unified two separate classes of equations, one set that could be used for massive objects moving slowly compared to the speed of light, and the other for light itself, into a single class of equations, one that not only included the two previous classes but made predictions for massive objects moving at speeds comparable to that of light.

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12 Responses

  1. Why isn’t Einstein also commonly compared with Maxwell? Maxwell also laid foundations for relativity. Maybe because Maxwell doesn’t have public name recognition?

    1. Maxwell also was a great unifier, and probably is one of the names mentioned most often in physics. Einstein, however, produced special relativity (revolutionizing basic mechanics and electromagnetism), general relativity (revolutionizing gravity), invented the modern notion of a quantum [specifically the photon] (revolutionizing our notion of waves, of light, and eventually of atoms), understood the statistical properties of bosons (think `lasers’), and did a number of other important things. I think he’s really the only person you can compare easily with Newton. But Maxwell is one of a number of legendary physicists who you’d definitely seat at the same table.

      1. Apropos comparisons to Maxwell, Mike Anthis forgot the elephant in the room: Faraday. Does Maxwell come up with his famous equations without Faraday? Hmmm…Interesting to dissect

  2. About extension of predictive mathematical power, does his mechanical equations contain the radiation reaction force? If not, is it truly relativistic and is it truly physical?

      1. You wrote: “If Einstein’s equations hadn’t contained those of Newton …” and I speak precisely of those Einstein’s equations for a charge (mechanical equations). I am afraid they do not contain the radiation reaction force so they cannot be completely physical and relativistic. Doesn’t that mean the relativity is not exact?

      2. I can rephrase my question: whether Einstein advanced a self-consistent system of equations for charge and field (a unification you speak of)?

        1. My history is insufficient to answer this properly; I need to do some more reading. But I think your question is irrelevant to the point I was making. I wasn’t speaking of the unification of charge and field, and in particular how charged particles and electric fields interact. I was only speaking about the kinematics for free massive particles and for free light waves. To make a fully consistent relativistic theory of interacting fields and particles required quantum field theory, and that was decades later.

  3. “……………the predictive mathematical core was not replaced, but rather was extended. ”

    I think this point is important. That for any “revolutionary change” there had to be some observation within an existing structure for any new theoretical definition to have become an offshoot and a possible new idea.

    Observation is key here.

    “Now that naturalism has become an accepted component of philosophy, there has recently been interest in reassessing Kuhn’s work in the light of developments in the relevant sciences, many of which provide corroboration for Kuhn’s claim that science is driven by relations of perceived similarity and analogy to existing problems and their solutions (Nickles 2003b, Nersessian 2003). It may yet be that a characteristically Kuhnian thesis will play a prominent part in our understanding of science.”-

  4. This strikes a responsive chord… 🙂

    You mentioned at Andrew’s party that you were working on this. On reflection I’m not sure that my “step on the gas” description was so inapt. It strikes me that it’s somewhat akin to what an architect does when successfully adding to an existing building (like, for example, extending a museum).

    1. Hi – I didn’t mean to imply that your “step-on-the-gas” comment was out of place. It was the the idea that Einstein’s revolution was unusual among modern scientific revolutions that I wanted to counter. This kind of scientific renovation is the rule, once a working and successful scientific structure is established. You need to preserve the old, because the old already works. [Although there’s a long and very interesting discussion to have about Kepler and Ptolemy here — Ptolemaic astronomy was actually pretty good, as a predictive framework, until enough precision was obtained to see problems, and until the telescope showed it failed badly in the prediction of the phases of Venus.]

      In recent days I too have been thinking through the architectural analogy, which I see as potentially very powerful. One can see many of the important scientific advances of the 19th and 20th centuries as taking two or three existing buildings, removing their exteriors, constructing a much larger structure with a novel design that nevertheless incorporates the older structures, and finally putting on a modern exterior.

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