Lunch With George!

November 1, 2001 - Villa Deli

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Agenda

• Show-and-tell
• G. Harry Stine
• The Comet Report
• Frame of Reference
• Gravity (reading assignment: Six Easy Pieces, Chapter Five: The Theory of Gravitation.

G. Harry Stine

Mr. Stine was an engineer and a writer (of both science fact and fiction). Here is his bibliography. George also notes that Mr. Stine was a dog-lover, and would host parties to which he invited other dog owners and their dogs. Duly inspired, George and Toni just hosted their 5th such "Puppy Pool Party", as reported in the October 4th lunch notes.

I did a little bit of research and found out that G. Harry Stine worked at White Sands in 1957, and also published the definitive manual on model rocketry! He also wrote a book that looks quite interesting: Amazing and Wonderful Mind Machines You Can Build I think I'm gonna get this!

A Comet Update

Figure 1: Comet Borrelly

As discussed here before, Dr. Tom Van Flandern theorizes that comets are NOT "dirty snowballs" from the Oort Cloud, but rather are rocky remnants of a planet which exploded between Mars and Jupiter millions of years ago. Does that sound more like an asteroid? Well, Dr. Tom believes they are asteroids that have not lost all of their satellites (smaller material which orbits around the comet).

I remember telling George several lunches ago that I read about two upcoming spacecraft missions to comets, and that their observations might lead to the support (or not) of Dr. Tom's theory. One of those spacecraft has already performed a relatively close flyby, as reported in the October 4th lunch. If you want to see more about the mission, visit the JPL site for Deep Space One.

George reports that the current Meta Research Bulletin (the quarterly journal of MetaResearch.org) contains a preliminary analysis of the DS1 data, and uses quotes from NASA scientists to support the EPH (Exploding Planet Hypothesis) origin theory for comets. The brief article compares the preliminary NASA data to EPH predictions:

• NASA says: "All over, the surface of the oblong object, roughly the size of Mt. Everest, is revealed as a rolling, pitted terrain marked by grand mesas."
  • Dr. Tom says: These are common features of rocky asteroids. This is consistent with predictions of the EPH.
  
  
• NASA says: "The new observations support other recent studies indicating that comets may not contain as much water as was once thought." This caused JPL astronomer Yeomans to refer to the comet as an "icy dirtball", rather than the previously-used cometary description "dirty snowball."
  • Dr. Tom says: Chondritic meteorites are about 15-20% water by volume, so we should expect this to be consistent with comets [since meteorites are typically associated with comets] . The EPH predicts that comets are rocky not "icy", so this is consistent with the model.
  
  
• NASA says: The cometary nucleus of Berrelly has an observed albedo of 4% [that's the amount of light striking it which is reflected back. A mirror has an albedo approaching 100%.].
  • Dr. Tom says: such a low albedo is typical for a carbonaceous asteroid, but much too low for a body made primarily of ice.
  
  

  Figure 2: Asteroid Eros

• NASA photo shows: an extremely elongated nucleus (see figure 1).
  • Dr. Tom says: This is consistent with a body having the strength of rock, but inconsistent with a low-density, porous, easily-broken object. It looks a lot like Eros (see figure 2), too![Eros is a well-known asteroid which was recently visited and orbited by the NEAR spacecraft. Learn more here.]
  
  

Face at Cydonia: The Meta Research Bulletin also included additional analysis of the most recent Mars photos with regards to the artificiality of the "face" feature. I'll try to summarize it on the Cydonia page when I get a chance.

Frame of Reference

"It is probably naive to ask, but how does the universe know that you are sitting on a piano stool spinning rather than that you are staying still and the universe is spinning around you?"

To which a reader of Pournelle's site responded:

"hold your arm out in front of you and let go of a tennis ball. If the ball stays in front of you (no gravity), the Universe is spinning. If the ball flies away from you on a tangent to your rotation, you are spinning. This test (or a similar one) is possible because a rotating frame is not an inertial one. The ball will follow a straight path in the inertial frame, so you immediately know which frame is which."

To which I replied, "I don't get it!" George tried to be very patient with me, and explained that because you are spinning on the piano stool, different parts of you (depending on how far from your center these parts are) are moving at different velocities.

My classic reply: "Different velocities relative to what?

George got that look again...

And I think he said "relative to each other." That when you are spinning, the movement is relative to yourself.

That's when a concept occurred to me that makes my brain feel better! I'm always uncomfortable with intertia. I always feel like inertia seems to be relative to a frame of reference, but George keeps telling me that inertia is relative to the object about which you are talking. Hmm. I was also feeling as though the "spinning piano stool" was another example of the inertia of the ball being relative to a frame of reference, when I realized that it IS!

George doesn't agree with me, but I feel the frame of reference is defined by the axis of the spin. All of your atoms are spinning (the ball, too) around a common axis, and everything observed happens relative to that axis (there is a force vector pointing straight at the axis, and when dropped, the ball continues to move along a path which is tangent to a circle described by its former movement around that axis.

Even if no one agrees with me, I feel better thinking that inertia exists relative to something.

Oh well. As Richard Feynman once said to Pournelle: "Sometimes things just don't make sense, and that's just the way it is. Live with it. More tea?"

Theory of Gravitation

"Many mechanisms for gravitation have been suggested. It is interesting to consider one of these, which many people have thought of from time to time. At first, one is quite excited and happy when he "discovers" it, but soon finds that it is not correct. It was first discovered about 1750. Suppose there were many particles moving in space at a very high speed in all directions and being only slightly absorbed in going through matter. When they are absorbed, they give an impulse to the Earth. However, since there are as many going one way as another, the impulses all balance. But when the sun is nearby, the particles coming toward the Earth through the Sun are partially absorbed, so fewer of them are coming from the sun than are coming from the other side. Therefore, the Earth feels a net impulse toward the Sun and it does not take one long to see that it is inversely as the square of the distance because of the variation of the solid angle that the Sun subtends as we vary the distance.

What is wrong with that machinery? It involves some new consequences which are not true. This particular idea has the following trouble: the Earth, in moving around the Sun, would impinge on more particles which are coming from its forward side than from its hind side (when you run in the rain, the rain in your face is stronger than that on the back of your head!). Therefore there would be more impulse given the Earth from the front, and the Earth would feel a resistance to motion and would be slowing up in its orbit. One can calculate how long it would take for the Earth to stop as a result of this resistance, and it would not take long enough for the Earth to still be in its orbit, so this mechanism does not work.

No machinery has ever been invented that "explains" gravity without also predicting some other phenomenon that does not exist."

I pointed out that Feynman (in 1960) felt comfortable using drag as an argument because he naturally assumed that any particle responsible for gravity would be bound by Einstein's Theory of Relativity and could travel no faster than the speed of light.

Personally, I'm having a little more trouble with Van Flandern's model for gravitation, since it requires not only the current thinking on gravity to be dead wrong, but also that relativity is wrong!

Van Flandern: I believe gravity is the result of tiny particles pushing masses.

Feynman: Ah! But what about drag on the masses if they're moving through the gravitons?

Van Flandern: Uh... they're... FASTER than light. Yeah! That's the ticket! A LOT faster! Let's see... in order to make them undetectable, let's say 10¹⁰c.