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A philosophy of philosophy

I started reading this book, "How to build a mind" by Igor Aleksander – a somewhat outdated book on so-called artificially intelligent systems, and systems which model thought processes similar to animals and humans.  The book touches on thoughts of what it means to "be conscious," among other things.  It seems the majority of the first chapters are about philosophical aspects of brain-building from "hardware" as built by humans, and while I had grabbed it from the library thinking it would be more about the actual physical side of things, so far it has been interesting if not a little light reading (well, quick at least, I’ve been over these sorts of thought-games before from such excellent books as "The Mind’s I").

That’s more intro than I had intended.  What I want to bring up is how apologetic Igor has so far seemed to be in how he deals with the naysayers for one, but more so with the matter of the philosophers who came before him – specifically, the many thousands of years of philosophical ideas which have been developed before him on the topic of "consciousness," as loose a word as that is, beyond probably the level of thought which I (nor he, likely) could hope to comprehend in some reasonable amount of time spent thinking.  So there are many schools of thought on the nature of consciousness, from that it stems from the physical structure of the brain, to it being some part of an ethereal soul, e.g., and so on.  Philosophers do not even agree amongst themselves on its nature, or better, how to tell if some thing has the property of "consciousness."

I’m not intending to jump in and debate this topic of mind.  It is there to illustrate a feeling about philosophy which I’ve felt building up in my head.  It appears to me that philosophy per se, in such topics as brain-building, where engineers and scientists can possibly build a physical model, is parallel in many ways to the type of thinking which theoretical scientists do.

It is a simple idea but I want to be clear about what I am getting at.  Since I’ve been through some amount of physics, I will use that as an example:  There are theoretical physicists, and there are experimental physicists.  It is typical that one spends their days drawing pictures while mapping out equations and programming computers to solve them, while the other plugs together electronics and computer systems with vacuum chambers and chemicals.  Never mind the often amusing banter and quarrel between the two about which of these disciplines is "better," it isn’t often that you get a physicist who is smack in the middle; there is usually a preference for building systems which take real-world data, vs. pushing the understanding and mathematics behind how the physical systems work.  When you do get a thorough mix between theorist and experimentalist, I have a feeling it makes for an astounding physicist, and it seems to me that Feynman was one of these, despite his claims of being a theorist.

To put it explicitly, theoretical physicists are every bit as important as experimental physicists.  Theories are necessary for experimentalists to know what to look for, and how to look for it – while experimental data is necessary in order to distinguish which theorist is closer to the truth and which one is truly off his rocker after all.  One side can push the other can push the other…  that is the way it is supposed to work; a dialog, like all science should be.  Now I do have a preference for the experimental side of things, because for one, when I set to learning about physics, I wanted to learn about the real world, what is true about it.  Theoretical physics is all in the brain, as is philosophy, and the seemingly best theoretical description of something is useless to describe the real world, if in fact the experiments show that it does not work that way.  Perhaps it can be altered to match the real world at best, or prove a good model within some limits (as Newtons equations do until relativity takes over).  I should note that there is a difference between theory, model, and experiment, and modeling does not relate enough to this article to spend time talking about it now.

In any case, that brings me to the point.  My philosophy on philosophy, at least as it relates to for instance the study of consciousness, is that it should be treated much like theories in science. Philosophical theories may certainly be interesting to think about, whether they are true or obviously not (like ancient Greek theories of gravity).  And for a long time I felt that that was just about the only use to it.  In fact I must admit that I still feel this way about certain people I’ve met in the field.  But like scientific hypotheses, philosophical arguments might just be able to point to answers to very real and very worthwhile things.  There may be those philosophies and philosophers who remain so far removed from reality as it applies to building a brain, but in this sense, philosophy can very well provide engineers and scientists with important questions to work on; and those same engineers and scientists can produce conundrums in philosophy (and ethics!) which we simply have not faced before in human history.

To lay out some examples:  It is a tough philosophical question of how one should live.  Does one follow the saying, "tit for tat," or is there another, better method?  Arguments can be made to justify just about any method of living.  It turns out that the field of game theory has come to show that "tit for two tats" tends to give better results in the long run.  There are certainly exceptions and I am not about to treat this scientifically enough to delve into it and provide sources; it is simply better for a group’s survival and so also an individuals’ to follow this model.  Being too much of a pushover is not advantageous, nor is being incredibly unforgiving.  So in this case a philosophical debate has been worked through by physical (or computed) models.  Like theoretical physical models, some philosophies were closer to the truth than others.  It is not worthwhile to be apologetic to those philosophies which got booted out, it is as useless as it is to cater to the theories which have been shown to be untrue.  Not that we should now start ignoring them completely; for one there is always a chance that the experiment had been wrong somehow, or perhaps does not actually apply to the theory/philosophy as it was first assumed.  For two it is dangerous to throw things out without a second look, in terms of advancing science.  There are many examples of the person with the correct theory being ridiculed and ignored before the science finally caught up and proved them out.  And then there is the practice of properly documenting things; why the theory is believed to be untrue, and so on.  If it only to make for good history, or it may prevent others from thinking to hard about something which has already been laid out.

A second example is how science has pushed philosophical questions. Professor Vladimir Chaloupka at the University of Washington has an excellent inter-disciplinary course outlining how this is so.  One such discussion is that, while many (especially including those in charge of large countries) may feel that war is a valid recourse or even first course against some wrong, never before have we had in our hands the ability to literally destroy all of human life on this planet.  With that, the philosophical question of how one should lead their life may deserve a thorough revisit…

This is about as far as I’ve come in my reasoning.  I’m sure this has been thought out before; I still dislike seeing the treatment of philosophy as if it is some ultimate grand thing, beyond the common person, when it has raised more questions than it has answered, and hasn’t exactly solved the world’s problems.  I’ll end by saying that, in this respect, science has done exactly the same!


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Homebuilt laser!

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Of all the cool projects I’ve been involved in during my school career through my Physics career, I’ve got to say that getting to build a custom laser is the one I’m going to have the most fun talking about.  Not that it is the most interesting project ever…but come on, a home-built laser!  It should be a requirement for getting a Physics degree.

The laser light itself is supplied by a laser diode, this one is actually a commercial one used in DVD reader/recorder units.  The experiment requires the use of light locked to a 671nm wavelength, but this is not in the range of commonly available commercial lasers.  Laser diodes actually emit a range of frequencies around a central frequency, which can be shifted by heat and also stimulation of a particular frequency.  In fact by shining light at precisely the desired wavelength of light back onto the diode, this increases the diode’s emission at that one frequency, and can narrow the amount of light emitted at other frequencies.

The trick we will use in achieving a 671nm wavelength is to use a Littrow-mount feedback system.  Light from the laser is shined onto a diffraction grating, which reflects most of the light.  A small amount of light is reflected at precise angles based on its wavelength, (as is expected from the physics of diffraction gratings), and the grating’s first-order reflection is made to reflect back onto the laser diode.  By changing the orientation of the grating, a particular wavelength can be made to shine back onto the diode (again, this is explained by the basic science of diffraction gratings – like a shiny CD, wavelengths hitting a grating are reflected at angles proportional to their wavelength), and so select the desired wavelength to stimulate in the diode.

The zeroth-order reflection (essentially the mirror reflection off of the grating) is reflected from a mirror, then out parallel to the original beam path.  The grating and mirror are mounted as a unit on a swing-arm in front of the diode laser, so that rotation of the mirror/grating unit can be achieved by a piezo-electric unit.  This allows the first-order reflection to be locked onto the laser, while not (largely) affecting the attitude of the outgoing beam.

The parts I have made were all from plans which the professor in charge of the Ultracold Atoms Experiment obtained through a group he had worked with at Berkeley.  So producing the whole system was quite straight-forward and took about a week of actual work in total, once all the parts were together.

Bare laser mount

In the picture above, the diode mount is a modified lens mount with aluminum blocks attached to the front end (the laser emits to the left of the photo).  The aluminum block with an angled cut and Allen screws on top will hold the diffraction grating, and the aluminum bar it sits on holds the mirror, as seen below:

Laser, Grating, and Mirror

The laser diode itself is behind the bluish collimating lens, which can be adjusted by turning the threaded steel ring around it.  The black cylinder around this is a commercial diode mount, with a layer of "thermal goop" between it and a modified mounting unit, with more goop between it and the modified lens mount.  The thermal paste helps heat get to the laser diode efficiently.

Down the front of the laser

Laser and Base

The unit as seen above sandwiches a thermoelectric cooler (TEC, also known as a Peltier device), which acts as a "heat pump" when current is applied to it, by moving heat from one side of its body to the other (the red and black wires attach to it).  This is all attached to a massive (about 7-8 lbs.) brass block, and its mass and a rubber sheet below it help to dampen vibrations which might make their way through the optics table.  Everything sits inside a housing box, which is lined with Acoustiblock material to keep out sound vibrations traveling over the table.


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Posted in Experiment, Physics, Projects, Work.

Ultracold Atomic Experiments

I have been working for some time with an Ultracold Atomic Experiment group at the University of Washington.  This has been one of my more enjoyable jobs, and has kept me busy machining parts, soldering together circuits, building lasers, taking pictures, and all sorts of other fun things.  The entire series of chambers is pulled to a very pristine vacuum – around 1E-10 torr or better.   Achieving such a good vacuum is a very involved and interesting process.  One of the steps is to heat the chamber walls to release embedded atoms so they can be pumped out; Below is a picture of the chamber wrapped in band heaters and other heating elements, which are each supplied power by one of the many variacs seen floating around the chamber.

Variacs!

The experiment will be trapping Lithium (Li) and Ytterbium (Yb) atoms, which get boiled off from separate ovens, slowed through Zeeman slowers, and combined into the central Magneto-Optical Trap, where they are further cooled by evaporative cooling until finally cold enough to settle into the lowest energy quantum state as a Bose-Einstein Condensate (BEC).  The projects I am or have been involved with include:

  • Create or Update Documentation for most projects
  • Data Acquisition Software and Hardware
    • Working with National Instruments Hardware and Software (interfaces with break-out boxes listed below)
    • Interfacing with Atticus/Cicero control software developed by a group at MIT
    • Digital Camera
      • Research and set-up of camera
      • Programming of User Interface
  • Construction of Electronics and Other Hardware
    • Diode Laser Lock Boxes
    • Lithium and Ytterbium Oven Control Units (Torture Units Li and Yb…)
    • 12 and 40 amp MOSFET switch boxes (BFW Housing Boxes)
    • Analog and Digital Isolation Break-Out Boxes
    • Enhancement Cavity Mode Lock Box
    • RF Driver boxes
    • 671nm Littrow-configuration laser
  • Create website for group
  • Take Photographs of experiment and lab
  • General Tasks
    • Troubleshoot/testing of various lab hardware and circuits
    • Organizing and maintaining electronics and other areas of lab (Research and purchase electronics parts)
    • Creating and now maintaining shared computer file system, software, and datasheets
  • Unicycle to Electronics Shop and back

Posted in Experiment, Physics, Projects, Work.

Michelson Interferometer – Part 2

This is the portion of my physics group project report that I wrote.

Interferometer Page 1


Measuring Static Frictional Forces using Interferometry

Interferometer Setup
Fig. 1:  Interferometer Setup and Labels
Fringes from Michelson Interferometer
Fig. 2:  Interferometer Fringes

Introduction

It is often not understood that even when dealing with static friction, application of less-than-critical sheering forces (that is, forces which do not cause breaking of static friction) creates an actual displacement between an object and the surface it rests on. The amount of movement is typically very small and barely if at all visible (displacement can be large enough to be seen when, for example, the surface is a rubber mat). When the sheering force is let off, static friction becomes a restoring force, returning the objects to its original position respective to the surface. This restoring force can be thought of as spring tension, and in this thinking ought to be proportional to object displacement.

This experiment sought to verify the linear F = k x relationship of static frictional forces between various materials at less-than-critical sheering forces. Very precise measurements of displacement were measured using a Michelson-type interferometer. The results showed a definite linear relationship between applied force and displacement of the test object for Styrofoam and particleboard surfaces.

Procedure

The first goal achieved was forming the ‘fringing’ patterns with the interferometer. The basic setup follows the Michelson interferometer design.

As shown in Fig. 1 , the beam emitted by the Laser (while a laser pointer is shown, a HeNe laser was used for actual collection of data) passed through one or two Lenses . The Lenses simply made the laser beam diverge and created a larger beam for viewing. The beam then hit the Beam Splitter , separating into two partial beams. Each partial beam bounced from a mirror back onto the beam splitter so that they overlapped and projected as a spot of light on a viewing surface (in the direction of the sheet of paper in Fig. 1). The Reference Mirror held a fixed position and created a reference beam. The Test Mirror was attached to a movable Test Block , and the surface under the block could be changed.

More difficult was developing the apparatus to precisely add and measure sheer force to the Test Mirror. The resulting design is shown in Fig. 3 (NOTE–Figure 3 isn’t here yet). The end of a Fishing Line was attached to a hook on back of the Test Block . The Line passed through the two Static Pulleys and terminated at the Force Probe . The Moveable Pulley could then be pushed into the Fishing Line, causing a Tension felt equally by both the Force Probe and Test Block. It should be noted that the Test Block and Force Probe were adjusted carefully so that they were directly aligned with the Fishing Line. In this way, the Pulley system ensured that only the desired vector component of force was applied to the Probe and Block.  When everything was secured properly, this system worked remarkably well and tension could be applied and held fairly precisely by hand.

A computer captured data directly from the calibrated Force Probe. To take a data run, the apparatus was first adjusted so little or no force acted on the Test Mirror and Force Probe. The state (bright or dark) of the central dot (see Fig. 2) was noted, the force was captured and 0 was entered as the fringe number. The Moveable Pulley was then pushed into the Fishing Line until the central dot grew into a ring with its alternate state in the center. The force was again captured and entered as fringe # 1. For example, in Figure 2, the initial central dot is red. If tension were applied to the Test Block, it would grow into a ring with a dark spot in its center. The dark spot becomes the new central dot, and was counted as one fringe when it became the same size as the original bright spot.

This process was repeated for multiple surfaces, and for most runs it was verified that as tension was let off the same number of fringes disappeared as had previously appeared. For the final run of a surface, the attempt was made to capture data until holding the Moveable Pulley became too difficult or the static friction bonds were broken and the Test Mirror slid out of position.

Interferometer Page 1


 

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Michelson Interferometer Part 1

This article describes the physics project I was involved in.

Interferometer page 2


Interferometry: Measuring Displacement on a Molecular Level

Our project is to very precisely measure static frictional forces between various materials. The high precision comes in using a Michelson-type interferometer.

Interferometer Setup
Fig. 1:  Interferometer Setup and Labels
Fringes from Michelson Interferometer
Fig. 2:  Interferometer Fringes

An interferometer overlaps two beams of same-frequency laser light. This creates an interference pattern due to the wave nature of light (Fig. 2). A laser pointer is shown above (Fig. 1), which is replaced by a Helium-Neon laser for the actual experiment, in order to gain more significant digits for the wavelength. As shown, the beam is first passed through two lenses. The only purpose for this is to make the laser beam diverge and ultimately create a larger beam for viewing. After the lenses, the beam is split into two partial beams using a half-silvered mirror (a beam splitter). Each partial beam is bounced from a mirror back onto the beam splitter so that they overlap and project as a spot of light on a viewing surface (in the direction of the sheet of paper in Fig. 1). One mirror holds a fixed position and creates a reference beam. The other test mirror is attached to a movable block. The surface under the block can be changed, and a measured force can be applied to it. Static frictional forces act to hold the block in place, but not without allowing some movement. When the force is let off, the block returns to its original position as if held in place by springs.

The interference pattern formed has the appearance of tree rings, with alternately bright and dark circles. What we are interested in is the central ‘dot’ which may be initially bright or dark. When the test mirror is shifted forwards or backwards, the central dot will grow or shrink. Assuming the central dot was initially bright, as it grows it will turn into a ring and a dark dot will appear at its center. As this dark spot grows, it also turns into a ring with a bright spot at its center, this pattern alternating. As the test mirror is shifted back to its original position, the rings will converge into alternately colored central dots. The appearance of each alternate-color dot corresponds to the test mirror having shifted its position by a quarter-wavelength of light – that is, 1/4 of 632.8 nanometers for the Helium-Neon laser ultimately used. This is roughly just over 1,100 times the diameter of a carbon atom!

Interferometer page 2


 

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