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photons, and on the other hand to explore whether the limit due to the universe’s size
has any implications for this issue.The question is still open.
In summary, it seems extremely difficult, if not impossible, to find modifications of
electrodynamics that do not disagree with experiment. Electrodynamics is fixed once for
all.
The brain: the toughest challenge for electrodynamics
Researchers working on classical electrodynamics still face a fascinating experimental
and theoretical issue: understanding the process of thought. Researchers face two challengesin
thisdomain. First, theymust findways to model thethoughtprocess.Second,
thetechnologytomeasurethecurrentsinthebrainmustbeextended.Inbothdomains,
recentprogresshasbeenspectacular.
Important research has been carried out on many levels of thought modelling. For
example, research using computer tomography, PET scans and MRI imaging has shown
that the distinction between theconscious and theunconscious can be measured: it has a
biological basis. Conscious and unconscious thoughts happen in different brain regions.
Psychological processes, such as repression of unpleasant thoughts, can actually be observed
in brain scans. Modellers of brain mechanisms are learning that various concepts
of psychology are descriptions for actual physical processes. This research approach is
still in its infancy, but very promising.
About the specific aspects of the working of the brain, such as learning, storage, recognitionofshapes,locationofsoundsourcesormapformation,modernneurobiology
andanimal experimentationhave allowed deducing models that make quantitative predictions.Moreonthiswill
betoldbelow.
On theexperimentalside, researchinto magnetoencephalographydevices is making
rapid progress.The magnetic fields produced by brain currents are as low as10 fT, which
require sensors at liquid helium temperature and a good shielding of background noise.
Improving the sensitivity and the spatial resolution of these systems is a central task. Also
computer models and algorithms are making rapid progress.
The whole programme would be complete as soon as, in a distant future, a sensitive
measuring apparatus could detect what is going on inside the brain and then could
deduce or ‘read’ the thoughts of a person from these measurements. Thought reading
might be the most complex of all challenges that science is facing. Clearly, such a feat
will require involved and expensive machinery, so that there is no danger for a misuse of
the technique.There are also good reasons to believe that full thought reading will never
be possible in this way, due to the lack of localization of cognitive thought inside the
brain and due to the variations in cognitive processing from one person to another. But
the understanding and modelling of the brain will be a useful technology in numerous
aspects of daily life, especially for the disabled.
On the path towards thought reading, the small progress that has been achieved so far
is already fascinating. Wearing a cap full of electric contacts – a so-calledbrain–computer
interface–andlooking at a computer screen,it is nowpossibleto type letters using the
powerofthoughtalone.SuchasystemisshowninFigure48.Theusercontrolsthecomputer
simply by imagining that he turns the arrow on the screen with his right hand.
The brain currents created by the imagination process are read out and translated into
Motion Mountain – The Adventure of Physics copyright © Christoph Schiller June 1990–November 2015 free pdf file available at www.motionmountain.net