I know of no accelerometer of any form, with a 10
20 or greater dynamic measurement range. Hence, I expect that the measurement was of some other [spurious] variable (probably electrical signal in nature) -- rather than acceleration due to a gravity-like field.
The experimenters claimed they measured an effect of 10-8 G, which was 1020 X larger than what they expected to measure. That means their accelerometers were expected to be capable of measuring an acceleration of 10-28 G.
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It would seem that the way to get "surprisingly larger than expected" results is ...to start with absurdly small expectations!
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I know of no accelerometer of any form, with a 1020 or greater dynamic measurement range.
***Thank you for verifying my claim.
Hence, I expect that the measurement was of some other [spurious] variable (probably electrical signal in nature) — rather than acceleration due to a gravity-like field.
***That means you’re looking for a propogation of errors. Perhaps one that starts out at 3 Orders Of Magnitude (OOMs), then propogates upwards 17 times, or maybe several parallel 3 OOM errors that propogate upwards only a few times. Again, that would make these experimentalists EXTREMELY stupid, right? Because they did the experiment 250 times.
The experimenters claimed they measured an effect of 10-8 G, which was 1020 X larger than what they expected to measure. That means their accelerometers were expected to be capable of measuring an acceleration of 10-28 G.
***Nope. Wrong. BZZZZZZZZT. If they KNEW they couldn’t measure an acceleration of 10^-28 G, but decided to look at this experiment ANYWAYS, and found MEASURABLE RESULTS at the level they COULD measure, then that DOES NOT mean “ their accelerometers were expected to be capable of measuring an acceleration of 10-28 G.” Basically, what you just posted was an invalid fallacy known as the argument from silence.
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It would seem that the way to get Post-Grad-Level scientists to stop posting freshman level fallacies is to.... give up that expectation!!!!
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As already stated, I'm unaware of any accelerometer capable of detecting such a minuscule (10
-28 G) acceleration level. However, for this discussion, I will examine a microsensor that is extremely sensitive, and discuss what steps might be taken with it to eliminate anomalous acceleration as a viable measurand -- and retain and isolate other, spurious (error-source) signal effects to be identified and eliminated (if possible).
Figure 1: The silicon micromachined integrated accelerometer illustrated in my #75 Is fabricated from two silicon wafers, with "active components" (signal processing circuity [differential amplifiers, etc,] and strain-sensitive piezoresistors [the "sensors"]) on their respective "front" surfaces.
The "back" surfaces are then "micromachined" (selectively etched into patterns to define micromechanical elements and provide clearance for them to operate) and are then aligned, facing each other as depicted in "Figure 1", below:
The accelerometer structure can be perceived as a "mechanical 'ground'" (overtinted in pink), and a "sensing structure" (in blue) which is basically a "square 'wheel'" with a central "hub" and a (relatively massive) "square 'tire'" -- with nanometer-scale thin ribbon "spokes" connecting the "tire" or"wheel" to the "hub".
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Figure 2: The microsensor is assembled by bonding the "hub" to the "mechanical ground" wafer -- immobilizing it, and fixing it at "mechanical ground", while leaving the "square wheel" moving mass free to move.. Electrical connections between the two "active component" surfaces are also established by this step.
Figure 3: The nanometers-thin, ribbon-like silicon "spokes" (overtinted in yellow) are where the sensing takes place. Each "spoke" has "piezoresistors" (resistors that change value, as a function of compressive or tensile stresses imposed on them) placed near the points where the "spokes" attach to the "Hub" and the "Moving Mass". The locations are where relative motion produces maximum flexure and stress on the piezoresistors -- ensuring maximum sensitivity to motion.
At this point, the microstructure is a complete, minute, but extremely sensitive and accurate, 3-axis accelerometer element. After it is packaged to provide protection, secure mounting, and interconnection to provide electrical connections to recording instrumentation, the microsensor becomes a fully-functional accelerometer.
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Now, we can look at what can contribute to measurement errors using such a micro-accelerometer -- and how to modify the microsensor structure to provide "control components" for isolating and identifying likely soures of measurement errors.
The questions I will be asking are precisely those I would ask the investigators in a Q&A session following a presentation of their work -- or around the coffee table, or, in front of the blackboard, with them, as I plan experiments to replicate their efforts.
What potential error sources can you foresee -- especially in proximity to moving magnetic fields?