The Real Story Of The Uncertainty Principle

Werner_Heisenberg_cropped[pictured: Boy Wonder, Werner Heisenberg]

I’ve always had my suspicions that physicists of today were misinterpreting the original assertions of Heisenberg’s Uncertainty Principle, that they were overstating just how nonsensical the world of the atom really is.  After all, they have incentive; no matter how wild their reputation-making and grant-justifying claims, theories, and supposed discoveries, they can always just shrug their shoulders at the incredulous and say, “Well, that’s the wacky atom for you.  ANYTHING is possible.”

After reading Manjit Kumar’s QUANTUM: Einstein, Bohr, And The Great Debate About The Nature Of Reality my suspicions of an over-inflated Uncertainty Theory are both confirmed and denied.

Here’s how it all went down…

Early Twentieth Century:  There’s this kid scientist (twenty-four) who is also a skilled mathematician named Heisenberg, and Heisenberg comes up with a complex mathematical way to describe the inside of an atom.  It’s pure genius, and his math formulations fit like a glove the results of the perplexing experimental results of the day.

Of course, his math didn’t make any sense, but there were ways around that.  Heisenberg’s math was non-communative (meaning that in his math (A x B) did NOT necessarily equal (B x A).  Someone else (Max Born) had to explain to him that this was okay because this is how one multiples “matrixes” (arrays of numbers arranged in a specific way).  Matrix Math is non-communative, said Born.  That must be what you used.  Oh yeah, said Heisenberg, that was it.  Only problem is, admitted Heisenberg, “I don’t even know what a matrix is!”

The math was one thing, but the physical interpretation was quite another.  Heisenberg’s equations were not solvable for some values of an assumed electron trajectory.  According to the math, the electron disappeared and reappeared along its journey through the atom.  In other words,  Heisenberg’s Matrix Math introduced DISCONTINUITY into the world of the atom.  This is the mathematical foundation behind the infamous “quantum leap”—the electron just jumps from one place to another, occupying no place in between.  Or so the math said.

Also, Heisenberg’s Matrix Math was not solvable simultaneously for Time, Position, AND Momentum of a particle.  It could tell you WHERE an electron is, or how FAST it is going, but not both at the same time.  Basically, as author Kumar explains it, the more accurately one value was determined, the less accurately the other could be determined.  Keep in mind… this is just the mathematical failure of the model… the logical justifications for the failure will come later (for instance, that the measuring an occurrence interferes with that occurrence and thus keeps you from knowing all its characteristics at once).

Problematic enough, some might think (not Heisenberg; he trusted math over common sense).  But then this man Schrodinger hits the scene with a groovy new Wave Theory.

Schrodinger’s Wave Theory said that electrons moved in an atom not as particles, but as waves.  Under this view, there was no longer any need for messy discontinuities or quantum leaps.  And to top it off, Schrodinger’s math was much simpler than Heisenberg’s Matrix Math (relatively speaking, mere mortals).  Since both Matrix Math and the Wave Theory proved mathematically equivalent, physicists naturally began to migrate toward Schrodinger’s work.

But though they preferred his math, many physicists still were not convinced that Schrodinger’s physical explanation of electrons was correct.  Instead of Heisenberg’s hopping electrons and discontinuity, Schrodinger contended that what everyone thought was a particle was actually a “wave packet”—a collection of waves that mostly interfered with each other, and thereby canceled one another out– except for their closely associated middle peaks– which moved around together.  This tiny remaining area of the waves was what scientists were mistaking for the particle they called an “electron.”

With the advent of Schrodinger’s new interpretation, Heisenberg could see his name slipping down the pages of the history books into a footnote.  He went into overdrive to discredit Schrodinger’s Wave Theory and shore up his own theory.

Heisenberg’s senior at the university, Niels Bohr, encouraged Heisenberg to incorporate Schrodinger’s new wave theory into his work, but that would have defeated Heisenberg’s ulterior motive to discredit the other, “wrong” theory and vindicate his own.  Physicists have feelings, too.

But this wasn’t all (at least consciously) about fighting for immortal fame;  Heisenberg trusted his math much more than the things people were making-up to explain the “reality” behind the math.  For Heisenberg, if his Matrix Math said electrons disappeared and reappeared like magic, then that’s precisely what they did.  He was also adamant that scientists should stick to strict observations and refrain from coming up with theories about the unknown.

However, in a letter to Heisenberg written about the time Heisenberg was tizzying over Schrodinger’s new theory, Einstein advised Heisenberg that scientists were always making-up theories about the unknown.  That’s what we do, he said.  Even the observations that Heisenberg put so much faith in required assumptions, explained Einstein…

Says Einstein to Heisenberg: “The phenomenon under observation produces certain events in our measuring apparatus.  As a result, further processes take place in the apparatus, which eventually and by complicated paths produce sense impressions and help fix the effects in our consciousness.” […] “You quite obviously assume that the whole mechanism of light transmission from the vibrating atom to the spectroscope or to the eye works just as one has always supposed it does”— and without that assumption, “you could not possibly observe any of the magnitudes you call observable.”  In other words, Werner my boy, even your vaulted observations are only assumptions.

Eventually, Heisenberg came out publicly with a competing particle explanation to Schrodinger’s wave theory of electrons, one that explained WHY his Matrix Math was not solvable for Time, Position, and Momentum simultaneously.

Heisenberg said that the very act of measuring the position of an electron made the simultaneous determination of its momentum impossible.  This is because, to see an electron, you need a photon of light (I think they actually used gamma rays to find electrons, but either way, visible light or gamma rays are both composed of photons).  This photon impacts the electron and disturbs it unpredictably.  Therefore, though you might find the electron’s position at the time of the photon impact, you have changed its momentum merely by the act of observation.

“No observation of atomic phenomena is possible without their essential disturbance,” said Bohr, agreeing with Heisenberg.  Bohr explained that it was impossible to draw “any sharp distinction between the behavior of atomic objects and the interactions with the measuring instruments.”

That is basically the true origin of the Uncertainty Principle.  However, things almost immediately got sticky.

Heisenberg, always trusting math and observation over conjecture, began saying that, because the position and momentum of an electron cannot be found simultaneously, the electron at any particular instance does not have position and momentum.  In fact, he said, in the absence of an experiment that measures an electron’s position and momentum, there is no position and momentum.  Heisenberg contended that it was the act of measuring, itself, that created the position or momentum.

Even Bohr, who was always trying to find a way to consolidate good theories, concurred that until an observation is made, an electron does not really exist; between measurements, the electron existed only in the abstract.

From here, the Uncertainty Principle continued to take on a life of its own, embraced by New Age philosophers and ambitious young theoretical physicists until, by mid-century, people believed that the theory asserted that Uncertainty was an intrinsic feature of reality, and that when it comes to the most fundamental aspects of the Universe, the whole notion of Cause-And-Effect breaks down– not because there are things we humans cannot yet see or understand, but because that’s the deeper reality of the cosmos.  God, Himself, cannot comprehend an atom.

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