Lunch With George!

October 4, 2001 - Samurai Sam's

Agenda

• Special Relativity (reading assignment: Six Not-So-Easy Pieces, Chapter Two: Symmetry in the Physical Sciences.
• If there's any time left...
  • skateboard
  • the Hobbit
  • tides
  • nanotech
  • VCDs
  • Iridium
  • Deep Space 1
  • Puppy Pool Party Photos

Miscellaneous Topics During the Meal

Once again, we covered a number of small topics while we ate (I had the Yakisoba...yum!).

Deep Space 1

Figure 1: Comet Borrelly

We've talked quite a bit about Dr. Tom VanFlandern's theory that comets are NOT "dirty snowballs" from the Oort cloud, but rather are remnants of the planet which exploded between Mars and Jupiter. Further, he theorizes (and has provided some proof) that the tails that appear are not caused by out-gassing as the comet is heated by the Sun, but are instead composed of small satellites of the comet which are dislodged by the Sun's overpowering gravity and then pushed away by the solar wind.

Why am I telling you this? Well, NASA's Deep Space 1 probe, a revolutionary spacecraft which has acted as a testbed for new space technologies (the most dramatic being an ion propulsion engine), just had a close encounter with comet Borrelly (see Figure 1)! More photos of the comet taken by the spacecraft, as well as other mission details, can be seen at NASA's Deep Space 1 site. Fred Glover says it looks like a potato!

Several instruments were used to study the comet, and I am hopeful that much of the data can help determine the validity of Dr. Tom's comet theories. Nothing has yet been posted at Dr. Tom's web site.

Ion propulsion is very exciting too-- ion engines produce a very small thrust, but can continue to run producing acceleration for years! To learn more, checkout the Hughes website for the NSTAR ion engine, or NASA's site about ION Propulsion.

Also, in my searches for information about ion propulsion (or did George find it? I can't remember!), I/we came across this entertaining website by a self-proclaimed geek named Michael Patterson: www.iondrive.com.

Reading
George didn't get to read much Feynman, but he did manage to read some of the Hobbit. George is using it as a starting point to read the Lord of the Ring series (there are a little less than three months before the new Lord of the Rings series of films shows up in theaters).

VCDs
Speaking of movies, I have a follow-up report on Video CDs (I first reported on VCDs at the September 6th lunch). My first VCD was a Disney movie, and I did not notice any video quality issues (as predicted). This time, I ordered three movies... all three Back to the Future films! I expected that with live-action film, significant video effects would be seen, due to the MPEG-1 compression. The big surprise was not that the video quality was poor, but rather the way in which I judged it to be poor.

All three films had a generally mediocre appearance... they looked as if I had taped the movies during a free HBO weekend at SLP speed. Contrast was not very good, and the image was not very sharp. The wierdness manifested itself in two ways. First, a vertical band of shading about 3 inches wide would slowly drift across the screen, taking about 20 seconds to traverse the entire width of the screen. Once it disappears off the right-hand side of the screen, it reappears on the left. This band was more noticeable during scenes with subdued lighting (George agrees this seems to be a result of analog processes, probably introduced during a transfer process prior to digitization and compression). Second, the compression performed for each movie handled rapidly changing scenes differently.

A quick note about MPEG video compression   MPEG achieves compression by only storing the changes from one frame to another. When the changes between each frame are small, such as when a person is standing still against an unchanging background, high compression is achieved, and the MPEG player which is decoding the data doesn't have much work to do applying the small changes to the image each frame. when changes from one frame to the next are large (like when a camera is rapidly panning to follow a flying DeLorean), very little compression can be achieved, since almost every pixel is different. This makes the player's job more difficult, and may tax its throughput. To make matters worse, the MPEG-1 format still has to meet its average compression, resulting in about an hour of video on a CD. if there are a lot of changes between frames throughout the video, something has to give (yes, it's QUALITY). I found another, more understandable site about MPEG.

When a rapidly changing scene appeared during the original film , Back To The Future, the resolution was sacrificed-- large pixel-blocks appeared in the uniformly shaded areas (usually the darker parts). This would dissapate quickly, and was not too distracting (I noticed because I was specifically looking for these kinds of issues).

When a similarly changing scene occurred in Back To The Future Part II, the compression algorithm took a different course. Since only so much data could be stored, it chose to drop entire frames but display the ones it retained at high resolution! while I suppose this preserved image quality, it was much more distracting while viewing-- the picture jumped almost as if it were a piece of film which has be spliced after a break. Oddly enough-- the audio was not interrupted! I can only assume that for every frame that was dropped, another frame was displayed twice.

The Bottom Line: I would definitely recommend VCDs only under the following conditions:

• Any animated films. The quality is very good, and the VCD format is cheaper than DVD.
• Live-action films that are not available in DVD format. There are a few notable titles, the original Star Wars Trilogy among them.
• If you have a fairly powerful laptop computer, but it only has a CD-ROM drive. With VCDs, you can still take movies on the road!

If you are interested in seeing the kinds of titles available on VCD, go to CoolVCD.com. They have a site that is easy to navigate, their customer service is very good, and even though they are shipping from Malaysia, I received my FedEx shipment in only four days, and that was only a week after the September 11 disaster.

Skate Board

We've had the "skateboard" topic on the agenda for three weeks... but we finally got to it! George said he never wanted a skateboard... until he spotted a new skateboard being produced by BMW. We both saw the article and photo in the Arizona Republic a few weeks ago, but George actually read it. Each wheel has an independent suspension system! I'll have to search the web and either get the photo or put a link here on this page. George and I both had the same thought when we first spied the new "beemer"-- it looks like something Y.T. would ride! Y.T. is one of the main characters in Neal Stephenson's novel Snow Crash.

Aha! I found some cool stuff on BMW's web site! It seems the suspension on the StreetCarver uses component design borrowed from the BMW 5 Series. I tried to go to the StreetCarver.com site, but it requires Flash 5. I did find that it retails for $495.00.

Photos
George brought me some print from his and Toni's fifth annual Puppy Pool Party! My daughters were there, and it just happened to be Hannah's birthday... so the dogs were all wearing party hats!

From left to right: Holly, Sophie, and Emily.

Tides
Another item that's been on the agenda for several weeks... George read Feynman's chapter on the Theory of Gravitation in Six Easy Pieces, and encountered the best explanation of why there is a high tide on the side of the Earth which is opposite the Moon, as well as on the side facing the Moon. Let's see if I can accurately remember Georges' version of what Feynman was saying!

OK, the oceans facing the Moon are pulled that way by the Moon's gravity-- that's the easy part. To understand the watery bulge on the opposite side of the Earth, we have to think about the dance in which the Earth and Moon are engaging. Compared to most natural satellites in the solar system, the Moon is quite large-- it's mass makes up a much larger percentage of the mass of the planet around which it orbits. This means the Earth and Moon earch orbit around a point which is a significant distance from the Earth's center (although it is still within the Earth's radius).

The resulting motion of the Earth is similar to twirling a frisbee around on the tip of your finger with your finger hooked under the rim of the Frisbee. Visualizing this, one can easily imagine that centrifugal "force" would be pushing out toward the rim of the Frisbee opposite your finger. This is the same thing happening on Earth! the water (and, in fact, everything on the surface) of the Earth opposite the "pivot point" around which the Moon and Earth orbit will be pushed away from that point by the centrifugal "force." It just so happens that the high tide is the only obvious manifestation.

Whew! I probably could have been more clear if I actually went and read the Feynman chapter... I'll try to draw a diagram (or lift one from the book). 10/7/01 - I did!

Iridium

I was telling George that I spotted a news article regarding the Iridium satellite phone system. Iridium Satellite LLC has submitted a formal proposal to the FAA to provide real-time monitoring and recording of data being sent to the flight data and voice recorders of every commerical aircraft. This may be the deal that keeps Iridium alive!

Nanotech

[George was kind enough to provide this summary!]
The article in Scientific American arguing against the plausibility of nanotech was written by Richard Smalley, who won the Nobel Prize for discovering buckyballs. He says that for a chemical reaction to take place you have to have a number of atoms in just the right arrangement within a very small region. He argues you can't have a finger trying to hold each of those atoms and move them into position - the fingers would be too fat and sticky to hold everything together without interfering with each other. He says that despite Feynman's statement that "There's plenty of room at the bottom", there's not *that* much room.

Figure 2: Hypothetical atomic assembler

Drexler counters that the need for so many manipulators has never been established or even seriously argued, and claims that designs have survived peer review that use just one tool at a time and grip their tools without using any 'fingers' at all. Figure 2 is a drawing Drexler presented in his 1991 book Unbounding The Future that shows a hypothetical assembler based on using the tip of an Atomic Force Microsocope to position the atoms. He proposes mounting a molecular tool holder on the microscope's probe that would grip tool tips containing atoms to be placed on the workpiece under construction. The tool tips could be washed in in a solution and then washed out after their atom has been used.

Symmetry in the Physical Laws

I was able to read most of the assignment, and found it very interesting. George was busy reading the Hobbit and flying to the East coast and back, so he didn't get very far this week.

This chapter dealt with "Symmetry in the Physical Laws"... but what does that mean? Feynman is trying to show which operations have no effect on the behavior/outcome of various physical phenomena. Here is a table (Table 2.1 from the book) which summarizes these "Symmetrical Operations:"

• Translation in Space
• Translation in Time
• Rotation through a fixed angle
• Uniform velocity in a straight line
• Reversal of Time
• Reflection of Space
• Interchange of Identical Particles
• Quantum-mechanical Phase
• Matter-antimatter

It is this last item which got me asking the question again: RELATIVE TO WHAT???? Here's my issue:

If you're on a spaceship moving at a uniform velocity in a straight line and you can't look out the window, you have NO WAY of knowing whether you are moving or stationary. I get this, and I can understand that motion itself is entirely relative in terms of the physical laws of the Universe.

But if you are in that same spaceship and it is set spinning about it's center, even though you can't see out a window, you can STILL KNOW YOU ARE MOVING! Not only that, but you can also tell that you are spinning around a particular axis, which implies to me an absolute frame of reference in the Universe.