A Subtle Attraction


by Brian Koberlein | 6 September 2018 | Physics

This is a companion discussion topic for the original entry at https://blog.briankoberlein.com/a-subtle-attraction/


Is the internal dynamics of Earth’s core stable and homogeneous enough to expect a stable high precision value? I would imagine whatever experiment is set up on earth, it would be under the influence of the earth’s mass distribution.


Yes, gravity experiments such as these are sensitive enough to exclude any “noise” from Earth’s gravity.


Is there a good reference on how this experiment is excluding this type of noise? In practice, the Earth’s fluctuations and things like the moon and sun would be very low frequency, so they’d need a high-frequency coding, or lock-in mechanism to integrate out this lower frequency noise/drift. Also, I’m assuming the pendulum was in a vacuum, but if it was able to accumulate even the most minute charge or gained a thermal or emission asymmetry, it would corrupt the measurement. Seems like a very difficult experiment to pull off – kind of like NASA trying to measure EM-drive thrust accurately.


Thinking about it, I don’t think you could get any accurate measurement on the Earth, because there are too many strong terrestrial fields, vibrations that are difficult to cancel perfectly, etc… You’d get better luck by studying remote spacecraft with transponders or radar. If you look at things like the pioneer anomaly, they were measuring an anomalous acceleration that was to many more decimal places than what CODATA specifies “G” to, yet they were using a filtered G as part of their determination. This is enabled by tons and tons of model-based filtering (kind of like averaging). This is the only way I can think of of getting a good G measurement.


The blog post cites the original research paper, which details the experiment.


Quantum tunneling
If we use this phenomenon in some slingshot pendulum which is perpendicular to Earth we may extrapolate parts in different phases and make sort of mechanical microscope, something how sonar works, but we would somehow make repulsion mapping based on how strong EM field changes in depend on two presets

  1. Tunnel setup
  2. Speed of vertical pendulum

Just an idea to the case of discussion.