Notes from April 9th

Just brought out of the archives...notes from April 9th.
This is a day when I was considerably late to class (in large part due to a screwy RTS schedule, but let's not go there)

On this day, Jeff (Pelz) and Andy (Herbert), the Vision and Mind lecturers respectively, came in to answer some of our questions.

This is based on the notes from another student who was there the whole time; while looking at the notes, I am trying to convert her note style into mine.
----------
* The world is broken down into little pictures, which your brain then puts together
* Since the system as a whole is so complex,. it helps to look at simple individual signals
* Yet, how does the brain combine these inputs into what is perceived as a smooth image? We don't know.

There exists something called the "binding problem" - action potentials [of the signals a neuron sends] are all-or-nothing, so the rate code (data speed and built in redundancy) is important
----------
[Editor's note: The following section has to do with a question I brought up often during this topic; i.e. what happens when something goes wrong in the system; and conversely, when someone has a sensory deficiency, what brain components are malfunctioning?

The prominent existence of NTID here at RIT has brought this type of question to the forefront of my mind. (yes, I know that the topic refers/referred to vision problems, but that is something I commonly find, that one topic jogs my memory on a somewhat-related topic. Furthermore, I recall from the lectures that several sensory areas are located in the same brain lobe, implying to me that they have interconnected or similar functions.)

Colorblindness was the main thing discussed in response to this question.

* With cataracts, the cornea is yellowing, warping the perception of certain wavelengths, especially on the blue end of the spectrum
* A lot of colorblindness has to do with errors in the retina's system of cones, which perceive color
** Some colorblind people don't have any, or the cones are not wired together properly

* Humans are trichromats, which perceive three different colors (R, G, B), and have different sets of cones that specialize in each. [this presumably in addition to light/dark white/black]. Soem humans are dichromats, which would logically mean a form of colorblindness compared to normal human perception.

Many animal species are bichromats or tetrachromats.

(At about this point of Andy & Jeff's talk, I show up and begin taking my own notes, that original post being located here: http://alan-labbook.blogspot.com/2008/04/questions-answered-by-andy-jeff.html)

[With the following comments, I'm not knocking the person who have me notes for 4/9, just stating facts/observations]

I notice that her style has more data fragments than mine does. (Granted, in the interest of keeping up the pace during the lectures, I often didn't use 100% complete sentences)

I find that different details are pulled out, but with the same general areas covered.

Note-taking is basically summarizing, and that's a task that different people ar eobviously going to approach differently.

Today's activity

Our tour guide - a Dr. Ferran

This is a bioscience research lab that I share with a couple other faculty

Dr. Sweet's aquarium - large amount of pencil urchins
She is a developmental biologist - studies organisms' gestation/etc.

Dr. Newman - human geneticist; studies generic patterns of age-related deafness
Human genetics & molecular analysis

Lots of collaboration in here with other people in the field

A lot undergraduate research assistants [they atleast get credit for it]

We don't run in to too many problems with the animal-welfare and religious-fanatic types

The Human Genome Project - provided a lot of raw data that we're just beginning to work with.

"Why couldn't God have released the source code with the binaries?" :P
More work needs to be done on proteins, though ("the devil's in the details.")


--------
We are now in cell-culture room
Not sterile but still above-average cleanliness
------
UV lightboxes have a sterilization effect

Some issue of our body contaminating the experiment, rather than the experiment contaminating us. (The types of pathogens we work with aren't seriously harmful to humans)

Big Bang and Black Holes: Topic Outline

What is important about the Big Bang And Black Holes topic?
I'd say it goes something like this...

1) "In the beginning..."

1.1) Singularity of infinitely small volume (and thus infinitely high temperature and pressure
1.2) This exploded/expanded - that event is the Big Bang itself

2) How do we know?

2.1) Hubble's Law - universe is expanding
2.1.1) Illustrated by Redshift [Light wavelength changes thanks to a stretching of the medium - space)
2.1.2) Extrapolate this backwards, and the universe would have been infinitely small at one point.

2.2) Cosmic background radiation
2.2.1) Remnants of the Big Bang explosion
2.2.2) Residual temperature in the universe of a few degrees Kelvin

2.2.3) Small temperature variations in this radiation - matter clumps; this clumping eventually aggregated itself into galaxies

3) What happened after the Big Bang?

3.1) Freeze-out of the "fundamental forces" - strong force, electromagnetic force, weak force, gravity [They used to be of equal strength, now they aren't - I just listed them in strongest-to-weakest order]

3.2) Inflationary Period
3.2.1) Especially rapid period of expansion in early universe (< 1 sec after BB)
3.2.2) Without it, the early universe would have had to have been relatively larg ein order to have reached the current size

3.2) Energy to Matter
3.2.1) E = M * C^2 : energy can be converted to matter...energy takes up less space than matter
3.2.2) Balance of matter annihilating antimatter, eventually regular matter won out
3.2.2.1) We don't know why regular matter won out

3.2.3) Big Bang Nucleosynthesis
3.2.3.1) Roughly 3min after BB. Occurred at temperature of 10^9 Kelvin
3.2.3.1) Particles coalesced into atoms
3.2.3.2) BBN only would have lasted long enough to form light elements.
Universe is made up of predominately light elements, this lending support to this important part of the Big Bang model
Various isotopes of hydrogen, helium, lithium and beryllium were formed

3.3) Later, stars and galaxies develop

4) The Cosmological Principle: important concept
4.1) Isotropic: Large-scale structure looks the same in all directions
4.2) Homogenous: General physical properties of the universe are the same everywhere in it
Thus, the universe has no edge and no center

5) What are galaxies?

5.1) The Formation of Galaxies
5.1.1) Galaxies formed about 1 billion years after big bang
5.1.2) Hierarchical merging [smaller-scale version of this process likely forms solar systems]

5.2) Different galaxy shapes

5.2.1) Spiral - a disk with spiral arms. Our own Milky Way is one. Relatively small nuclear bulge. Relatively large amounts of young stars and star formation.
5.2.2) Elliptical - Dominated by spheroid. Relatively old
5.2.3) Irregular and Peculiar - Those terms mean what you think they mean. :)

5.3) Galaxy relations: Galaxy clusters, superclusters

5.3.1) Galaxies do gather into clusters

5.3.2) Supercluster Types
5.3.2.1) Rich - >1000 galaxies, giant central galaxy
5.3.2.2) Poor - 10 to 1000 galaxies, more spirals
5.3.2.3) Isolated galaxies - even more likely to be spirals

5.3.2) Galaxies in superclusters not gravitationally bound to each other

6) What are black holes?
A superdense object, to the point where its gravity is so strong that not even electromagnetic radiation [light] can escape

6.1) Fuller explanation of black holes is provided by Einstein's theories of relativity

6.1.1) Spacetime - space and time are connected (they are *relative* to each other)
6.1.2) Gravity is dependent on spacetime
6.1.3) Special relativity predicts/explains unusual behavior that occurs with abnormal values of space, time, and/or gravity

6.2) Now, if no electromagnetic radiation, visible light or otherwise, emerges from a black hole, how do we study them?
6.2.1) Their effect on visible bodies near them: For ionstance, a black hole may suck in gas from nearby stars

6.3) Black holes are the Las Vegases of the universe - what happens [goes into] in a black hole stays in a black hole.
6.3.1) This is how black holes build mass
6.3.2) Difference: Actions in Las Vegas may also cause alimony, child support or prison time to increase

7) Dark Matter and Dark Energy: The Monkey Wrench in the Cosmological Works
We don't know what it is; hence the name 'dark'.
Nonbaryonic ("Baryons" are a type of particle with protons and neutrons being the most notable examples of them)

7.1) Composes most of the universe


7.2) Dark matter:
7.3) Dark energy: even more "weird" than dark matter

-More to come-

Visit to Jeff Pelz in his image lab

Wearable eye tracker vs. lab-based eye trackers

* In-lab: Purkinje eye trackers: Purkinje is reflections off of the eye, a "glint in someone's eye"

* Investigate different questions in different envirnoments
* Limitations of the lab: people may behave differently in a lab environment, and Perkingi trackers require the head to be immobilized
* In-lab equipment has faster frequency and higher accuracy

* SOme equipment is based on video cameras rather than eye-trackers

When reading: small smooth movement ( a word) with jumps to the next word and the next line. Sometimes regression moments to rereread something

In our terms, a "gaze" is when you look at one object, rather than an entire scene, but w/o keeping your head/eyes totally still
Modeling gaze: what you fixate on in an image, how long, and why. | By modeling gaze, build a model of what you think people will look at, and compare it with experimental data

In 1/10 of a second, you get the general idea of an image (i.e "This is a kitchen")

bottom-up: start with pixels and then form a concept
top-down: start looking for a concept and then doscover the details [i.e. pixels]
For top-down you need to have an understanding of the concept you are looking for

Notes from the semiconductor lab we visited last week [April 25th]

We visited a semiconductor facility a week ago; this is on the RIT campus as part of the engineering program's apparatus (specifically, Microelectronic Engineering)

The most obvious thing is the 'clean' in 'clean room', and some of the cleanliness measures employed were rather interesting.

It's a Class 1000 cleanroom, meaning them aim for less than 1000 particles per cubic foot.

For instance, outside laptops weren't allowed in (because of dust & related crud that may be in the keyboard), so this post is actually a rough transcription of my paper notes [plus some additional commentary on the lab].
For really hardcore microelectronics engineers, there's special paper that 'sheds' less particulates into the air.
The full-body suits were interesting and amusing-looking, we collectively looked like future astronauts or something.

Air pressure is slightly higher inside, so that clean air rushes out and dirty air doesn't rush in when access doors are opened

The day before our visit was "Bring your Son/Daughter To Work Day", and our tour guide remarked that the gaggle of 5-year-old present looked rather cute after bieng outfitte din the suits.

Sodium is a really bad contaminant. [editor's note: so no salty munchies in the lab!]

------------
Anyway, their equipment is sufficient to produce microchips from beginning to end, but it's all atleast a few years old. (and thanks to Moore's Law, that makes the chips quite out of date; but the value is there as an educational tool.) Furthermore, most of the equipment was donated by
big names in the field (such as IBM and Intel) after *they* upgraded.

Furthermore, consumer-photography companies like Canon, Nikon, and Kodak are also involved in this type of industrial equipment. [The photoresist process, important to semiconductor manufacture, does involve exposing the silicon wafer to a certain amount and type of light in certain areas of the chip.]

Makes sense in a way, because as is common for RIT, grads often end up going right work with one of the big-name companies in their field
-------

So, roughly speaking, how does the process actually work?

* A block of processed silicon is 'sliced' into wafers, and each of those wafers will become a large quantity of chips over the course of the manufacturing process. Thus, each batch of microchips necessarily contains a large number of individual chips.
* With lithography, a printing process, computer-designed patterns are put onto the wafer
* Then we apply photoresist; we apply it over certain parts of the wafer, so that some areas of the chip 'resist' when exposed to light and some won't [this forms the pattern]
* The photoresist is exposed by a certain wavelength of blue light from one of the lab's machines

To prevent accidental exposure, the lightbulbs in that area are yellow and the windows are tinted. I recognized this as being analogous to the use of red-colored lightbulbs in traditional photofilm darkrooms.

* Ion bombardment, towards the end of the process implants material into the wafer that makes it more conductive. (Yes, we discussed silicon for quite a while before mentioning implants. :))
------
Dangerous chemicals are important to the semiconductor process, but one sign in the lab touched upon this with a note of humor:
"You can walk on a wooden leg, you can eat with false teeth, but you can't see with a glass eye. So wear your safety glasses."

Personal Interest Presentation: outline-in-progress

I'll edit this post as I develop more ideas for my outline

"Space, the final NanoPower frontier"

[Insert badly photoshopped picture of the Enterprise]

0)
Nanotech has potential in all areas of space exploration.
Nanotech will not immediately create new fields/devices, but rather, it has the potential to greatly improve existing devices. (especially in the near future)

0.1) Short overview of why we should be trying to use nanotubes (reference their positive charcteristics)

1) Existing use of nanotech in space
1.1) Space Nanotechnology laboratory at MIT (snl.mit.edu) has used nanotehc to build nanoscale components of NASA observers [Chandra X-Ray and others]

2) Nanoelectrical systems

2.1) Power systems, PMAD [Power Management and Distribution] systems
2.1.1) Applications in nuclear powersystems
2.1.2) Applications in solar powersystems

2.2) MEMS [Microelectromagnetic systems]: Combine microchips with electronics that would use them.
2.2.1) Important spacecraft electronics could be made smaller.
2.2.2) Micro-probes for imaging extraterrestrial objects

3) Nanocomposites as a spacecraft building material

3.1) "Armoring" against space debris
3.2) Useful in dealing with stresses of launch?

4) Types of space exploration; usage of nanotechnologies there

4.1) Deep-space travel
4.2) Colonization of extraterrestrial worlds

4.3) Surface exploration [using nanotech]
4.3.1) by humans

4.3.2) by probes/robots
4.3.2.1) Nanotechnology could enable you to build very small probes.

5) Use of nanotubes to transport stuff from Earth to low-Earth orbit
5.1) A space elevator?
5.1.1) Exciting theoretical possibility, but even the theory isn't completely ironed out yet.

* Many parts of this presentation will reference concepts discussed during Ryne Rafaelle's two presentations way back in Week 2. My notes are on this blog, and I still have access to the powerpoints, so memory of that material shouldn't be an issue.

Personal Interest Presentation

This is the "final exam" for the Frontiers of Science class.
The idea here is to zoom on on sub-area(s) of any of the four topics covered, specifically sub-area(s) that especially interest you

I am focusing on the use of nanotechnology and NanoPower in current and future space exploration. To put it more lyrically,

"Space, the final NanoPower frontier"

To be honest, good sci-fi works can have quite a potential to be inspiring as to the course of scientific advancement.

A centerprice of our classroom is a widevision screen that, among other things, could display 4 PowerPoint-type slides at a time, and we have a PowerPoint template file designed to work with that.

The crux of my Personal Interest Presentation s going to be one of those, which is a process I've also used for the three topic summaries I've done to date.
The format is one I understand, and I'm also using it because I'll hopefully be able to focus on content rather on the logistical & production issues of a more exotic format

Medical Imaging

X-rays: very good for imaging bone, but not soft tissue
Still useful on kidneys - would see kidney stones

Before Roentgen's X-ray discovery, no way to look at body besides cutting it open

Some medical imaging methods (like X-ray) provide a picture, some (like ultrasound) provide a real-time picture

Where in the electromagnetic spectrum do we look?

Two parameters: resolution and attenuation (attenuation: how the radiation changes as goes through the body during the imaging process). Often, it is a tradeoff between the two.
Both of these parameters are a function of wavelength

We can't medical-image with visible light, since the human body is opaque to it

-How X-rays work-
Tungsten cathode: bombards tungsten target with electrons, the target is hooked up to a copper anode
X-rays produced by the electron/target collision

X-rays are 2D representation of a 3D object; thus aren't good for analyzing abnormal structures where you aren't sure what structure to expect

-Computer tomography-
Uses X-rays
Takes 2D images of a 3D volume (like the human body) - "slices" - target needs to be aligned straight with the beam generator
Several of these images, aggregated into one picture

Backprojection: Looking at the same slice of the body from different angles

-Positron emission tomography (PET)-

Proton --> Neutron + Neutrino + Positron
[Part of radioactive decay: inject radioactive agent during PET to cause this to happen]

Positron + Electron: antimatter annihilation that produces a gamma-ray signature. The latter is detected

Areas of higher metabolism (like cancer tumors) give off a stronger signature

-MRI-
This has been covered before
Hydrogen protons on particular become excited in a strong magnetic field, then turn the field off, which thus changes the signal behavior.
You image based on this.

-Ultrasound-
Useful on pregnant women because it's safe/not radioactive
Has other uses as well

We know the speed of sound in the body because know the speed of sound in water, and the body is mostly water

You image based on the ultrasound's echoes

Doppler ultrasound can image blood flow

Visible Human Project: part of NIH
Gathers data about human body parts that can be use din designing and tweaking these imaging processes

modality: a term for a different medical-imaging process

Often get complementary images from using different processes on the same object
Could look at these images side-by-side or no top of each other

Images often pseudocolored to help humans read + analyze them

Simulated/"phantom" images are often useful for gathering general information

Outlines [Vision And Mind example]

This came to mind as I'm working on Topic Summary #3:

An outline is a good way to prep for doing the topic summary, but it's also a good way to think about the topic, in general.

So here goes:

-Vision And Mind-

* the physiology of the vision system

** details on structure of the eye
*** Rods & Cones

** details on the visual cortex and on V1 through V5
*** where it's located compared to the rest of the brain.

** "lateral inhibition", and how it accentuates the edges of an object

** eye movements
*** depends on the size of the object/scene to be visualized (the object/scene to be visualized is counted in degrees squared)
*** oculomotor system
*** saccades
*** various ways of tracing a moving object

** field-of-view vs. acuity conflict
-------------------------------------------------------
* the psychology of the vision system

** How can we visualize brain psychology?
by various medical-imaging techniques:
*** EEG
*** MRI vs. fMRI, differences

** How certain optical illusions work
*** really should be 'neural illusions'?
*** name a few big-name optical illusions & discuss them
----------------------------------------------------------------
* relation to other senses
** brain lobe where inputs from other senses 'meet'
** use of visual system to compensate for other sight loss
** use of other sensory systems to compensate for vision loss

Halstone's electron-microscope lab

This lab uses TEMs (tunneling electron microscopes)

Can't use glass lenses to focus electron beams; have to use magnetic lenses; this *is* a tradeoff

X-ray microscopes don't have the quality we want yet, gamma-ray microscopes are still atleast a few years down the road

Mosely's law - 1914: hit something w/ electrons and produce X-rays

* Radiation issues inherent
* Depending on the energy level of the X-rays, you can tell what element emitted it


Electron gun fires a beam down the main column
Tungsten filament is excited and

200,000 volts
200,000 kilo-electron volts

Moving at ~ 1/3 the speed of light, need to use Relativity-based equations

Specimen in center of column, on the end of a handle

Whole column has to be under vacuum

One magnetic lens controls spot size of beam; there are several other lenses aswell

Objective lens nearest the bottom of the column; it's what actually produces the image.

^ How do you *see* electrons?
At bottom of column, a screen covered with zinc sulfide...Electrons put some part(s) of that into an excited state, and they flouresce green.

Green-ness caught by film

X-ray detectors chilled to liquid-nitrogen temperatures.
This can be used to analyze what elements ar ein each section of the sample

Specimens extremely small (~3mm diameter, and very thin (<200nm, even thinner for heavy elements))

What is 2,000,000x magnification? A person magnified this much would be two thousand miles tall?
What is a nanometer versus a meter? Size of a golf ball versions the size of the Earth

Electron microscopes very sensitive. Even sound waves form talking, etc. can cause the image to 'jump' a bit

Electron diffraction - electron beam scattered by hitting a crystalline structure. Depending on how they scatter, you can determine what the crystal structure is. Often a ring pattern of some sort.

Lattice planes in asbestos are 9 angstroms (.9 nm) apart

Easy to detect dead space in a crystalline structure vs. the location of the atoms themselves

--------
*Scanning electron microscope*

Shorter column
20k eV up to 30k or 40k eV

Secondary electrons kicked off by the sample itself


Can vary distance between sample and electron beam

General good microscope idea: start at low magnification to get an overview, then zoom in

A high frame rate leads to more noise "static" (spend less time scanning a particular pixel)

Low frame rate - less "noise", but takes longer to produce the image

Low voltage; less penetration; should mean more surface detail [and vice versa]

SEM useful for building a picture of where exactly atoms of element X are located throughout the sample

H, He, Li, and Be can't be detected via this X-ray detector equipment

astigmatism: vertical image in separate focus from the horizontal image

Spehrical and chromatic aberation you need different equipment to correct
---
Halstone uses a srtaightforward same (copper+aluminum disk) to calibrate the settings

---
The material you used to prepare the specimen (gold coat, etc), can screw with the view

How do they work?

Okay, how do these types of medical imaging work?

* Ultrasound

How it works: Bombardment of sound waves above 20,000 hertz (20khZ), 20khz being the upper limit of human hearing

What is actually measured: Ultrasound actually measures the echoes received by the ultrasound machine after they bounce back from hitting body parts.

An electrical pulse transducer in the machine causes it to vibrate at a certain frequency. Likewise, the echoes cause the transducer to vibrate in various ways, converted into electrical pulses which are then converted into a digital image

Advantages: Light if any side effects, very good at imaging soft tissue (vary frequency for different kinds of soft tissue), can produce a "live video" feed during the procedure

* fMRI (Functional Magnetic Resonance Imaging)

How it works: Images the brain and brain activity, though the method would technically work on other areas of the body
What is actually measured: It does this by detecting the increased blood flow typically associated with neural activity

How does it act as a proxy: Neural activity kicks up blood flow, with the areas of increased blood flow being measured

* SPECT

How it works: Radioisotopes fed into body, and the gamma rays are detected by the SPECT equipment
What is actually measured: The rays received by the machine are measured as 2-D images, but are measured form different angles, enabling a 3D image to be produced

How does it act as a proxy?: See info about 3-D reconstruction method above. Also, the radio decay particles behave differently when passing through different body structures, hence the ability for this to measure anything at all

* electromicroscopy


How it works: Magnifies samples to a much higher degree of resolution than is possible with a light microscope.

What is actually measured: Very small/thin sample bombarded with an electron beam. As electrons go through the object (in tunneling electron microscopy, or TEM), they are recorded as how they were 'behaving' as they come out

How does it act as a proxy?: Impediments inside the sample modify the outgoing electron beam.

Types of Medical Imaging

We'll be investigating some forms of medical imaging in class on Wed. (4/25) and Fri. (4/25)

Now what are the different types of medical imaging?

-Things that analyze brain waves, even though they aren't imaging something visible, are still a form of medical imaging-

* such as electroencephalography (EEG)

Many techniques exist that take images of physical body parts...

* X-rays (Classic!)
* Magnetic resonance imaging (MRI) + fMRI
* Positron emission tomography (PET)
* Computerized tomography (CAT)
* Ultrasound

--
endoscopy
* SPECT
* radioisotope-based techniques: nuclear medicine + flouroscopy
* thermography
* electron microscopy
* Raman spectroscopy
* image guided biopsy
* angiography

Electron Microscopy

Electron MIcroscopes come in two forms: The Tunneling Electron Microscope (TEM) and the Scanning Electron Microscope (SEM).

What is the difference? Both use beams of electrons.
However, the difference resides in the fact that the different types of machines direct the electron beam differently.

Tunneling Electron Microscopes send an electron beam *through* the object. This means theta they are good at gathering details on the inside of the object (which is especially important with cells), and of the surface of small objects.


Scanning Electorn Microscopes send their electron beams along the outside of objects. They are most effective for analyzing the surface of large/thick objects

The STEM (Scanning transmission electron microscope) combines some of the advantageous features of each, logically enough.

There are online simulators, based on Flash, Java, or the like, that give you an impression of how an electron microscope works. By adjusting settings common to an electorn microscope, and chosing from a premade set of 'samples', you see the resultant image.

http://micro.magnet.fsu.edu/primer/java/electronmicroscopy/magnify1/index.html is an example

Questions answered by Andy & Jeff

TMS = transcranial magnetic stimulation

Blinded or blindfolded people - this frees up processing capacity in the visual cortex, some of which is used for other types of sensory processing

In deaf people, the auditory cortex probably does something

Same parts of brain for thinking about something, and perceiving it. So thinking about something during a dream may helpyou perceive it when you're awake

During sleep, the memory-forming hippocampus is more-active
Sleep is mental regeneration (see above), as well as physical regeneration

Cramming - does not work for long-term retention

Eye -->LGN --> V1 --> V2 --> V3 --> V4 --> V5
Not always a linear pathway, there are some connections that skip/go backwards in this chain.

The different V's process somewhat different types of signals (have different capacities), but these roles are interconencted. (Removing V4 doesn't

LGN - laterogenetic nucleus of the thalamus

Allan Cowe - vision experiments on monkeys

The brain is to some extent a dynamic self-repairing system

At a certain point, the things [experiments] we want to do are illegal or unethical - Andy Herbert
Don't overdo the computer analogies here in brain psychology

SOme optical illusions are the result of the brain taking necessary processing shortcuts

"Is what we see really there?" - That gets into philosophy

Integrating the senses is important - Sense A compensates for a weakness of Sense B
Normally, the senses paint a complementary picture...very disorienting when they don't

Contrast sensitivity - vision of shadows vs. vision of discrete objects
Different among different species, because different species need visions systems adapted to their different environment

Can see what capacity is missing when a certain section of the brain is gone.
First started relazing this en masse with Civil War musketball-to-the-head injuries

Cortex has higher-order roles than things like the thalamus. Things liek the thalamus handle basic body functions for the most part.

Drugs,and not just the funky illegal ones - have effect on neurotrasmitters.

Range of visual sensitivity amongst normal humans
This may explain how a lot of drugs produce haalucinations and the like

(4/4/08) Answers to Thought-Provoking Questions

Why do some stars turn into black holes?

Stars that were massive enough turn into black holes when they die.

A dead star doesn't have enough fuel to keep fusion going.
The fusion reaction produces energy and heat that counterbalances the gravitational pull of the star on itself
This is called "hydrostatic equilibrium"

Objects in a system orbit around the center of mass
Galaxies in a cluster kind of orbit each other rather than expanding and spreading out the way the Hubble pattern would predict. SO they become more inclined to collide.


What keeps smaller object in orbit, rather than falling towards the central mass?
* the energy of the small object itself
* orbit is at a point where energy of object balances the energy of gravitational pull

gravitational tides between galaxies can affect orbits if the galaxies are close enough
During a galactic collision, you're likely to have more material falling into a black hole

Time travel very speculative - all of the discussion is theoretical at this point. Some ways time travel might happen:

*Faster-than-light (back in time)
*Travel through wormhole w/o getting destroyed
* Go to similar parallel universe

* Are parallel universes preexisting, or created by the act of time travel


* If parallel universes exist, there would probably be an infinite amount of them, for each branching-off point. If there was a limited amount,how would it be chosen?
* Parallel universmany not just have different history, but different laws of physics

Standard candle - a group of objects with the same brightness.
Different form units of measure such as "solar luminosity"


Standard rod -similar concept with shape

In astronomy, can measure apparent brightness and apparent size.

apparent brightness, apparent size, actual size, actual brightness and distance - if you knoow some fo these, you can figure out the rest

"Do black holes ever go away?"

The massive ones are around forever,the smaller ones are likely to disappear

The Drake Equation - equation that takes several factors; determines the probability of intelligent life; however, you have to make assumptions

E = mc^2

E = mc^2 actually refers to particles without motion, plus the energy of motion

With the energy of motion, you can have mass of 0, and still have energy

Applies to many different areas of the universe

E = mc^2: A recipe for converting matter to energy and vice versa - requires energy to make such a conversion, and a lot of energy

Energy doesn't take up much space, takes up more space when converted into matter

(4/2/08) - From Big Bang to Black Holes

Most of what we know about the universe comes from our analysis of electromagnetic radiation (i.e. light)

Light is like a wave
Electronic wave and magnetic wave oscillate together

Black hole in center of galaxy = 1 million times the mass of the sun
The Sun = a basic unit of measurement

ergs = g*cm^2 / second^2

Solar luminosity = 3.8 * 10^33 ergs/s

Mass: 2 * 10^30 kg
Age of universe: 13.7 billion years
Speed of light = 3 * 10^8 m/s
parsec = 3.26 light years

Special Relativity

2 main components:
* The laws of physics ar ehte same in any inertial frame
* The speed of light is the same for all observers in an inertial frame

Spacetime is 4-dimensional

A frame in which unaccelerated objects move in straight lines is an inertial frame

A globally inertial frame is a frame that covers all spacetime

Addition of speeds

Walking 5 mph, Bus 30mph, difference 25mph

Rocket 100,000km/s, Light 300,000km/s

Difference appears differently because the observers involved see spacetime differently

Time dilation: the time lapse between 2 events changes from one observer to another; it is dependent on the relative speed of the observers

Lorentz contraction - the dimensions of an object as measured by one observer may be smaller than that of another observer

This also has implications for how gravity works

Newtonian gravity: F = G (m1 m2)/r^2

General Relativity: mass-energy causes spacetime to curve

Objects, including light, follow the shortest path in curved spacetime

Gravity = curvature of spacetime

Clocks more slowly the closer they are to a gravitational mass

Sun's gravity would bend light coming from background stars

Time slows near any massive body. Slows down even near Earth. [albeit in very small amounts - 4 parts in 10 billion]

The angular momentum of a rotating body drags space into a tornado-like whirl around it. (small whirl

Will see object differently if a mass is on the way. This is called a "gravitational lens".

When the gravitational lens is perfectly aligned with the background object, the background object is modified into an Einstein Ring

Black holes - so much mass in such a small space that the spacetime warp is extreme

Nothing can escape, not even light

Detect black holes by their gravitational effect on nearby object

Stars, specially those near Galactic Center, are detected orbiting it

Supermassive black holes probably exist at the centers of most galaxies
Called galactic nuclei
Could have come about or become larger during galactic mergers

Collision of two black holes is the most violent event in the universe
* Produces wild vibrations of warped spacetime

Black holes related to their host galaxies: "chicken & egg" problem
* galaxy formation far enough back in time that we can't really tell
* Hypothesis: growing together

What happens in a black hole, stays on a black hole. This is how black holes build mass.

(3/31/08) From Big Bang to Black Holes: Part II

The Big Bang
The Evolution of the Universe
Galaxy Formation and Evolution
Dark Matter/Dark Energy
The Big Questions
Future Prospects

--
-Basic Forces-

Strong nuclear force - Holds nuclei together: Strength 1, Range 10^-15 m, gluons + nucleons
Electromagnetic Force - Strength 1/137, Range Infinite, photon [mass o] [ spin 1]
Weak - Strength 10^-6, range 10^-18m [0.1% of the diameter of a proton], intermediate vector bosons, W+, W-, Z0,mass > 80 GeV, spin =1
Gravity - Strength 6 * 10^-39, Range Infinite, [potential gravitron particle], mass =0, spin = 2

Cosmological principle - isotropic [large-scale structure looks the same in all directions] and homogenous [general physical properties are the same everywhere]

The universe has no edge and no center

-Hubble Law-
On large scales, galaxies are moving apart, with velocity proportional to distance

There is no center of expansion
Spacetime itself is expanding and carrying the galaxies with it

^ Can tell this via cosmological redshift


Redshift = (wavelength - original wavelngth) / (original wavelength)


Extrapolating backwards w/ Hubble's Law = universe had a beginning [infinitely small and hot] - the cosmic singularity

(Planck's constant t = 1.35*(10^-43) sec

--
We should expect thermal radiation from hot gas
Radiation should is blackbody spectrum

Initially, all four forces were equally strong.
Broke off in the following order: gravity, strong force, weak force
Gravity broke off (forze out) within 1 Planck time of Big Bang

First Galaxies - Approx. 1billion years after Big Bang

Bizarre inflationary period - exponential expansion of universe soon after Big Bang

W/O inflationary period, universe would have had to start out relatively large

Infationary period theory - explains lack of magnetic monopoles, horizon problem, flatness problem

Horizon problem: things far enough apart that they didn't come into contact with each other
Flatness problem: near critical energy density (eqiuilibrium point between infinite expansion and infinite compression) - Sphere needed to move from a small size (high arc) to large size (low arc) quickly

Initially, was equilibrium between pair production and annihilation (between regular matter and antimatter). There was a slight shift in favor of regular matter

Then, atomic nuclei were created (a few seconds after the Big Bang). This settled out a few minutes after the Big Bang.

This initial process created hydrogen, helium, lithium and beryllium (along with hydrogen isotope deuterium). Mostly hydrogen/helium.
Other elements were formed via fusion in the center of stars.

As universe expanded, it cooled down, cooled down to a point where atoms formed, and electrons were not allowed to interfere with photons anymore, because they were locked down in atoms

Cosmic Background Radiation was predicted as a 'signature' of the Big Bang.
R. Wilson and A. Penzias won the Nobel Prize for discovering this in 1978


Highly isotropic - intensity of this radiation very similar in all directions
Perfect blackbody spectrum would have a temperature of 2.725 Kelvin

Slight nonuniformity explains the clusters of matter that ended up as galaxies


Spiral galaxies: relatively small nuclear bulge, disk with spiral arms, gas/dust/star formation/young stars
Barred spirals are 2/3 of all spirals; they have elongated nuclei with spiral arms emerging from the ends

Elliptical galaxies: squashed-sphere shape, largely old stars

---
Even seemingly empty patches of sky probably contain very distant, faint galaxies
Most galaxies are members of clusters; galaxy clusters themselves are grouped into superclusters [many superclusters have a few dozen clusters spread out over ~40 Mpc]
Superclusters are *not* gravitationally bound

Rich Clusters - >1000 galaxies, ~ 3Mpc diameter, condensed around a giant central galaxy
Poor Clusters - 10-1000 galaxies, more spirals
Isolated galaxies are mostly spirals

Hierarchichal merging - start of cloud og gas, which starts telling out and clumping into discrete entities.
Galaxies were formed this way, and probably solar systems aswell

Star birth comes about relatively early in the universe (0.5 - 1.0 billion years ago)

Dark Energy - 70% of universe
Dark Matter - 25% of universe
Free H, He - 4%
Stars - .5%
Neutrinos - .3%
Heavy Elements - .03%

By the way gravity is behaving, we know there has to be a certain amount of mass, not all of which is visible matter - hence, dark matter

Is dark matter baryonicor nonbaryonic? Most probably nonbaryonic

Gravity should slow down expansion, dark energy should speed up expansion

Current data pointing to expansionary model; we're not sure.

Topic Summaries

Topic summaries are a major part of this class' assignment mix.
They consist, of, well, a summary of each topic the class covered. (There are four separate documents involved; one for each of the four topics)

We're given latitude in what format to use.

Common is the old standby; PowerPoint (However, this has to be done well; not just simple bulleted text and the like)

Our classroom has some special equipment that can be summed up as a 'immersive environment'. A large part of this is a wide special screen, which actually seems to consist of four panels. Easier to see, and with the capability of displaying more information at a time. One of the things it can do is display four slides' worth of information at a time, and I am using for my topic summary a Power Point template designed to work with this feature.

Tags

Tags

The Frontiers of Science class covers 4 topics: Viruses, NanoPower, Vision and the Mind, and Big Bang/Black Holes

Blogger's tag system is an excellent way to sort out which posts go with which topics:

http://alan-labbook.blogspot.com/search/label/Viruses
http://alan-labbook.blogspot.com/search/label/NanoPower
http://alan-labbook.blogspot.com/search/label/VisionAndMind
http://alan-labbook.blogspot.com/search/label/BBBH

http://alan-labbook.blogspot.com/search/label/Administrative
http://alan-labbook.blogspot.com/search/label/General