My first Transmission Electron Microscope

Last spring (2007) I made an electron microscope with my lab partners at PSU. Using an old article from the 1960’s, Becca, Brad, some guy (I think his name was Hank) and I constructed the contraption out of an old beaker, some wire, two metal spools, some rubber stoppers, a vacuum pump and a whole bunch of volts.

The general design principles can be seen here.

In theory, we should have been able to fire some high energy electrons through a pair of electromagnetic lenses and create an image on some phosphorescent material that we coated onto the beaker. A specimin holder sits between the coils and holds the sample (which gets bombarded with electrons). The image is created by the electrons that manage to pass through the sample.

I wrapped the coils by hand and made the specimen holder.

We could never pull a good enough vacuum. The purple color you see early on in the clip is due to contamination of air in the chamber. There should be little to no gas in that first chamber.

The green dot that shows up on the beaker is proof that we got our microscope to fire electrons. The white phosphorescent material coating the tube is glowing due to the high energy electrons striking it.

I attached a bug wing to the specimen holder and we hoped that the electrons transmitted through it would appear on the beaker as an enlarged image of the wing. We ended up just cooking the bug wing.

We could never get the beam focused on the sample. Our lenses were not the right width apart to be able to focus on the tube. I think it is still sitting up in Science Building 2 at PSU.

I wrote the tune last night.
(shot in the dark on my HV20)

~20mb - let it stream…

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Big Triangles

A few years back, people believed the world to be flat. It is now generally accepted that the world is spherical. One has to be appreciably far from the earth to observe its spherical form. The fact that it is a sphere allows airplanes and communication satellites to circumnavigate around it and connect our world. Otherwise, we all keep pretending it’s flat anyway and don’t think much about it.

Similarly, our universe has three possible shapes: flat, positive curvature and negative curvature. The jury is out as to which form it has. To understand the implications of curved, or non-Euclidean space, let’s imagine a triangle overlaid on top of the globe.

From this picture, we can see that the triangle intersects the equator at right angles. Our curved space triangle now contains more than 180 degrees within its angles, not possible in Euclidean geometry.

If our universe is curved, an object traveling in a straight line may not be going straight at all. A jet flying north may seem to be flying straight on to its passengers, but in reality it is following a curved path around the globe.

If we were to aim a beam of light towards a Alpha Centuari (towards where it would be four years from now of course), it would most likely arrive in tact due to the incredibly boring and empty stretch of four light years that separate us. Like our airplane, would the light have traveled in a straight path to get there?

Light sent from Earth to Alpha Centauri
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I had an idea about measuring the shape of the universe. Using some basic geometry, spectroscopy and simple measurements, we might be able to look deeper into this.

Modern telescopes allow supernova events to be recorded with great detail. If one of these explosions can be observed inside a symmetrical nebula, the light energy escaping from it could tracked over a series of years.

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(I got this movie from here.)

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The luminous border of the nebula, depending on its composition and density, would expand at or nearly the speed of light. This has been shown in Supernova 1006, which took place about a thousand years ago.

The lateral growth of the nebula represents the base of our interstellar right triangle. With a little geometry, we might be able to figure out how our universe is curved (at least between us and the supernova).

Light emitted from a Supernova heads to Earth
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Why does it matter?

The shape our universe is what will determine its fate. Without going into details, if you have any interest in the future, higher powers, fate and such, this is it.

Concerns:
The gas particles in the nebula will slow the light down. Absorption spectra could be used to determine the composition and (possibly?) the density of the nebula.

Space may not be curved enough to be observable at the given distance.

Does light play by the rules? We know it is affected by gravity but how would it interact with curved space?

This is not meant to be a scientific exploration. It’s just a thought I had while daydreaming in class.

We should make some big triangles to figure out how it will all end…