About a hundred years ago, physicists groping for a way to conceptualize the atom, applied the macro to the ultra-micro, and used gross-movement descriptors such as “Orbit” and “Spin.” Within a few decades however, the ideas of Orbit and Spin, as physically true characteristics of the atom, had been proven highly unlikely. Subatomic Orbits were replaced by either “Clouds” or “Waves,” and Spin was proven impossible since it would require surface revolution-velocity exceeding the Speed Of Light (considered the ultimate speed limit according to another modern set of physics-rules). This was all accomplished by the mid-20th century.
But it seems not everyone got the memo. Or rather, many scientists simply chose to ignore it. For physicists doing actual hands-on work in the different realms of applied sciences — such as, say, semiconductors or magnetic resonance imaging– it proves convenient to continue thinking in terms of the old, erroneous paradigm of Orbits and Spins.
Quixotically– and, to my knowledge, entirely alone in the universe at the moment in this endeavor– I try, in my essays, to acknowledge the inconvenient truth that we do NOT really understand the physicality of the atom, and — what is worse– we think we DO. Even the world’s most thoughtful and successful physicists either ignore, have forgotten, or don’t understand that subatomic Orbit and Spin are false mythologies, created by the daring, imaginative, and free-wheelin’ (hell, slightly reckless really) physicists produced by the enthusiasms of early 20th technological breakthroughs.
In this post, after wrestling, off and on for weeks with the subject between other projects, I’ve decided to attempt a general explanation of how Magnetic Resonance Imaging (MRI) works– without resorting to the incorrect, quasi-planetary conceptualization of the (actually still quite mysterious) atom.
Even if I fail in the attempt, the struggle has been a valuable reminder to me of something I already knew– that we all already know– that it is almost impossible to re-train the mind to think in truly new ways once the fundamental categories and grooves of its thinking have become entrenched. I have notions of Orbits and Spins and Protons and Electrons so beaten into my head for so long –and from such an early, formative period– that even with the power of my own convictions to sustain me, I sometimes falter and catch myself falling into the old, improper mindset…
On one level, Magnetic Resonance Imaging is simple to grasp…
A body is placed inside a compartment subjected to three different electromagnetic fields; one field applied lengthwise, a second widthwise, and a third, heighthwise. The three fields form a three-dimensional axis-system we typically label the X, Y, and Z axes. Basically, it’s just like the old graphs on the X-Y coordinate-system we used in Math class, with an additional “Z” axis coming, as it were, straight out of the page at us.
If we know the precise paths of the axes (or dimensions), and if they can be labelled or potentially labelled in predictable increments of predictable values, then we can describe the location of any object, anywhere within the space reached by all three axes.
By way of a mundane example, I can tell you where, exactly, you may find my baseball-glove if I give you its precise latitude (X-axis), longitude (Y-axis), and height above or below the ground (Z axis).
Magnetic Resonance Imaging uses three different directional sources of electromagnetic fields to create what amounts to the three axes we need to locate objects in space. They create the predictable increments necessary by applying the fields so that they gradually and predictably change their strength over the distance being evaluated. Thus, the fields are applied with a gradient.
To illustrate… Let us suppose that the lengthwise field is applied to a body so that the field changes in value the farther away from the source one measures it… its values along the length of the body may take on the values of, say… 1, 2, 3, 4…
Now, let us suppose the same is done with the widthwise field, so that its values change over distance according to the pattern of… A, B, C, D… And the heighthwise field changes just a predictably as the other fields, but with the produced values of… a, b, c, d…
In this way, every point of the body can be exactly scanned in a three-dimensional way. A point on the hand might have the tri-field value of, say, “5Fh.” Whereas, a point on the foot might be assigned the value (or Coordinates) of “9Tp.”
In this way, the MRI machinery produces a precise, 3D map of the body. Once we can 3D-image the body’s bulk, half the problem of MRI is solved. HOWEVER…
Merely knowing there’s a body there in the device doesn’t tell us a heckuvalot– we already knew that much. The next step is to be able to know WHAT material is occupying each location in three-dimensional space.
MRI accomplishes this by sending extremely strong magnetic field-pulses through the body. These powerful pulses affect the body at the ATOMIC level. Because each tissue comprising the body reacts differently to the electromagnetic pounding, by reading the signals received back from the body between the pulses, technicians can see what sort of tissue is filling each location of the body– atom by atom!
The atoms of some tissues bounce back quickly to their normal state after each magnetic blast. Others take their time. By registering how quickly each atom returns to form, technicians can create a 3-D image of the body, inside and out, showing the shape of each life-giving– or life-threatening– material in the body. The intestine can be seen, as well as a tumor on the intestine, since each material will respond differently from the magnetic pulses being shot through the body.
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The practicalities of the MRI procedure are extremely well-grasped and applied, and have saved and improved millions of lives.
However, it is when scientists attempt to conceptualize what exactly is going on at the atomic level during MRI scans, they revert back to explanations utilizing the long-outdated paradigm of Orbits and Spins. In the day-to-day application of the technology, this doesn’t matter. Technicians need only be able to correctly conduct the procedure and productively analyze its results. In the same manner, early Man stumbling from the Bronze to the Iron Age did not need to understand the physics behind their smelting process to produce valuable structures, tools, and weapons.
Scientists describing MRI will speak of “aligning Spins” and “Precessional frequencies,” but these are hardly more than convenient conventions. All we know in a practical sense is that materials respond differently to intense magnetic-field bombardment.
So-called “Spin” has been used to “explain” magnetism for decades now. The biggest harm done from this false belief is that it assuredly has kept great minds from exploring the true nature of magnetism along completely different lines– believing as they do that we already know the general principle whereby magnetism is generated. Once we can shake off the 100-year-old, false paradigm, who knows what next-level discoveries we may make!
Magnetism is explained as the alignment of Electron “Spins.” When the Spins of Electrons (pretending for the moment Electrons really exist!) are aligned parallel, magnetism is (still quite magically!) claimed to be produced.
And yet, MRI ignores electrons completely! What scientists claim to measure in MRI is Proton-Spin. In their naive interpretation, their pulses of electromagnetic energy causes “Protons” (pretending for the moment THEY really exist!) to “flip.” It is claimed that Protons flip because they absorb Energy from the electromagnetic blast received. Scientists like to think they have crawled away from superstitious ideas, but in the end, we often still have to resort to that great, movement-initiating Spirit or God that today goes by the name “Energy.”
Scientists have also snuck into magnetic theory, by the back door as it were, a SECOND creator of magnetism in addition to Spin– Precession. Precession is supposed to be the revolution of one end of a Proton around a hypothetical line drawn through space– specifically, a line of force contained in the oncoming waves of electromagnetic energy bombarding the Proton. The concept of Precession allows scientists to continue operating within their same old paradigm since a “Precession” around a line-of-force is not all that differently applied than a “Spin” around the axis-of-the-proton.
My guess is that Precession was added to the mix because scientists needed a way to conceptualize the discovered fact that a SECOND applied magnetic field could affect material simultaneously with the first applied field. If there was only aligned Spins to play with, then once one magnetic field had claimed the allegiance of parallel Spins, it becomes problematic to explain why the material is behaving magnetically in ANOTHER field-direction at the same time. It could be done, and perhaps was even tried, but the additional Spin-like concept of proton-Precession proved less troublesome.
Additionally, with the idea of Precession added to the mix, it becomes easier to explain how a THIRD applied magnetic field is effectual simultaneously on the material. The explanation is that two fields affecting a proton’s Precession simultaneously will cause the Precessional orbit to switch from a circular to a spiral shape.
We DO know that only certain frequencies or ranges of frequencies of the great Energy-Spirit cause major responses in any particular substance. But things become immediately murky after that…
Sure, we can state that “Energy” is “absorbed” by an “atom” (or a “Proton” or an “Electron”), but this concept is half-understood (what the heck IS “Energy”?! and should we be praying to it?) and probably also at least half-wrong (do “Electrons” REALLY maintain individualized identities inside atoms?). And sure, we can speak of atoms (or whatever) as being “excited” or “vibrating” or exhibiting “resonance”– but these are mere abracadabra words.
Sure, let’s smelt what we can smelt, and scan what we scan, but if don’t truly understand the underlying physics, let us not pretend that we do. Assertions handed down unquestioned from generation to generation, whether coming from Aristotle or from Heisenberg, shut down fresh lines of inquiry, close eyes to otherwise obvious inconvenient facts, and make mushy even the most magnificent mind.
Science advances farthest and most sure-footedly when we have the courage to admit what we DON’T know.