[MD] Dawkins a Materialist (is watching?)

[Hamilton Priday]

Micah --



> How did we know to come up with a device to detect things
> we're not aware of?

That's an excellent question, Micah, and I suspect that you're raising it to 
support what seems to be your "subjectivist" view of reality.

Craig has provided a good reference to the types of phenomena detectors and 
measuring instruments are used for and how they work.  But this tells only 
part of the story, since what you're asking is: How do we know such 
phenomena exist?  Let me try to answer this from the objectivist viewpoint.

It is true that most electromagnetic radiation is undetectable to humans, 
except of course for the narrow band of relatively large waves that are 
visible to the eye as light, and a wider band of shorter wavelengths that 
are felt as heat.  In fact, it is the effects of electromagnetic energy that 
led scientists to devise the various means of monitoring it.

For example, you remember the Curies who used pitchblend to generate Röntgen 
radiation (x-rays) and won Madame Curie the Nobel prize for experiments that 
led to the development of medical radiography.  Pitchblend is the ore from 
which uranium is extracted, yet was more radioactive than the uranium.  By 
1898 they deduced that the pitchblend contained traces of an unknown 
radioactive substance far more radioactive than uranium.  Curie named this 
substance radium, and her death from aplastic anemia in 1934 was almost 
certainly the effect of her exposure to this substance.  Since monitoring 
radiation exposure was critical, subsequent research led to the invention of 
scintillation counters which "convert" x-ray photons to visible photons and 
the Geiger Counter which measures the ionization rate of gases exposed to 
radiation.

Since the 1970s, new semiconductor detectors have been developed that 
convert x-ray photons to electron-hole pairs in the semiconductor which are 
then collected to detect the X-rays.  Practical application in Medical 
Imaging didn't occur until the 1990's.  Amorphous selenium is now used in 
commercial large area flat panel x-ray detectors for chest radiography and 
mammography.

Another observed effect of radiation that was applied to a whole new 
technology is electro-fluorescence.  In the early 1900s it was discovered 
that cathode rays (a stream of electrons produced by a negative electrode) 
cause phosphors on the glass wall of a vacuum tube to fluoresce, an effect 
which eventually made possible the CRT now used to display television 
images.

Similar histories can be cited for spectroscopy, the oscilloscope, x-ray 
astronomy, x-ray microscopy, and laser technology.  In all of these 
developments, it was the observed "effect" of an unknown source of energy 
that initially led to a suitable detecting device (to identify the source), 
and eventually to an invention that could put it to practical use.  The same 
could be said for the invention of the barometer to measure air pressure, 
the thermometer (temperature), photometer, (light), spectrograph (color), 
audiometer (sound), voltmeter (EMF), ammeter (electric current), etc.  I 
think one could safely say that all "detecting" instruments are designed to 
measure and/or identify a phenomenon whose effects we are sensibly aware of.

Now that I've explained the objective view, perhaps you'll tell us how the 
"subjective" view is different.

Essentially yours,
Ham,