David's Unknowns FAQ

updated 2003-10-12. Contents:

  1. David's Unknowns_FAQ
  2. news
  3. About this FAQ
  4. Personal achievement
  5. human relationships
  6. The human mind and artificial intelligence including
  7. Physics
  8. Biology
  9. Engineering
  10. Mathematics
  11. Theology and Astronomy
  12. science fair books
  13. misc

Related pages:


Other web sites with the latest "unknowns" news

About this FAQ

I hope these are "useful science fair projects". As far as I know, all these things really *would* advance human knowledge -- what's the point of yet another clay volcano ?

Is there some other net resource that already catalogs these things ? Another science fair FAQ ?

This is my attempt to catalog those things which are not yet known, but may become known in the future. It started as a personal quest to discover those areas where my personal knowledge is lacking, and now I've expanded it to attempt to cover those areas where the knowledge of the entire human race is lacking.

If you ever hear the phrase "No one knows X", please send it on to me to be added to the list. (I expect to be taking things *off* this list as things are discovered -- perhaps I'll start a new list called "recent discoveries", that gives the answer and/or points to official listings).

Especially if you've already figured out some method of answering it, but then calculated "Whoa ! That equipment will set me back $1000 ! This just isn't worth it." Perhaps someone else can take your idea and sqrounge (how do you spell that?) up cheaper components or find some clever cost-reducing trick #clever_tricks. Or maybe you can find 10 other people that *do* think it's worth $100 each to learn the answer. Then you would know the answer to that question that's been bugging you, and all it takes is a few moments to send me some email that inspires someone else to find that answer.

I'm more interested in those little questions that could be answered by a dedicated high-schooler for a science project than in Big Unanswerable Questions.

If anyone does know the answers to any of these questions, please send me a pointer to the answer so I can take it off this list.

Bill Beaty http://www.eskimo.com/~billb/freenrg/ideas.html seems to have independently come up with a very similar idea.

Edmund Scientific http://edsci.com/ is one source of science-fair equipment when it cannot be scrounged; do you know of any others ?

If you find any lingering factual errors, or if you can think of any way to improve this net resource, please tell me d.cary@ieee.org.

"It is not enough to say that "X"s simply mean unknown, because we need to define what we mean by "unknown"."
-- Clive "Max" Maxfield, Intergraph Electronics, in article "Xs in digital simulation: Beware, here be dragons!" in _EDN: The Design Magazine of the Electronics Industry_.

"We demand rigidly defined areas of doubt and uncertainty!" -- Vroomfondel

There has been an alarming increase in the number of things you know nothing about. -- ???

_U.S.News and World Report_ 1997-08-18 has several articles on things that would fit in this "unknowns" file. For example, "What is sleep for ?" article by Thom Geier.

Personal achievement

Q: How do I win the Nobel prize in physics ?
A: Easy, just read and follow the directions in the "Open Questions" section /* http://hermes.astro.washington.edu/faq/physics/open_questions.html offline ? */ of the sci.physics FAQ .

More information about the Nobel prize:

Q: How do I win the Gordon Bell Prize (called "the Nobel Prize of computing") ? [FIXME:]

How do I get to Mars from here ? How much will a flight to Mars cost ?

"Is this it?" and, "What am I doing all of this for?"
-- tjallen (Timothy Allen)

"Will there be pink flamingos in the gardens at L5?"
-- Anders Sandberg http://www.nada.kth.se/~nv91-asa/main.html [Date: Wed, 24 Jul 1996]

"I'm in Pittsburgh. Why am I here?" -- Harold Urey, Nobel Laureate

the human mind and artificial intelligence

There are some things we do know learning.html#brain about the human brain.

But many other things about the human brain are still a mystery.

One thing in particular stands out: What do humans want ?

also see What causes the ``Flynn effect'' ?

While Turing's original version used a *human* judge who attempted to discriminate between humans and computers pretending to be human, apparently several people have made *programs* that are pretty successful at discriminating between humans and computers.

What causes the ``Flynn effect'' ?

up: the human mind and artificial intelligence

DAV: Imagine that we discover a technique that always improves a child's IQ test score. Should we try to make these changes to more children's environments ? Or does training children in ways that increases their scores on one kind of test inevitably make them worse at wisdom, tact, history, and other abilities that are not tested ?

more AI:

human relationships

[FIXME: better title ?]

Here are some things about humans -- not individual humans themselves, but their interactions with each other. (If you take *any* human and isolate that human from others, that human is technically no longer civilized).

what do humans want ?

what do men and women really want ?

see also "Ask for what you really want" creed.html#really_want


Q: What takes more power: Moving the hands around an analog watch, or keeping the current time on a LCD digital watch ? On a digital LCD watch, how much power does the LCD consume, and (if the LCD is disconnected) how much power does everything else consume ? (I'm sure lots of people know this; but I don't)

partial A: ``The LED watch ... the electrical current consumption of these watches ranges from 10 mA, without display, to 10 mA in the dark and 100 mA in full light, the two batteries need to be replaced twice a year. This is the main reason the production stopped within a few years after first release. From that time the Liquid Crystal Display watch (LCD) with an energy consumption during display a few thousand times lower than that of a LED watch'' -- http://www.xs4all.nl/~rkeulen/watch/led.html

Q: Where does dust come from ?

Q: What affect, if any, does air humidity have on the melt rates of glaciers ?

Q: What are Red Sprites and Blue Jets http://elf.gi.alaska.edu/ ?


Newsgroups: sci.physics
From:  (Matt McIrvin)
Subject: Re: Cosmic rays - a question
Date: Sun, 12 Jan 1997 18:26:50 GMT

...  (russell wallace) wrote:

> My question is, how can any natural process that could possibly be
> consistent with the laws of physics as we currently understand them
> produce these?  Even supernovas, about the most violent events known to
> present day science, would normally emit particles carrying energy of no
> more than the order of their own mass.  Doesn't a naturally occuring
> particle with energy equivalent to 1e9 times the mass of a proton
> require postulating as yet unknown physical laws to explain it?

It's possible to give particles energies much greater than their own
masses, with particle accelerators. However, some of the cosmic-ray
particles are so energetic that their production is far beyond the
reach of any known physical process. Nobody knows where they come
from, and the available theories are very speculative. It's a real
mystery at this point.


Matt McIrvin

Mitch has given me a pointer to a partial answer to 2 of these questions (Thanks, Mitch !):

From: mitchP 
Date: Tue, 18 Feb 97 14:38:01 EST
Subject: cosmic rays, and the scope of gravity

You can find recent preprints pertaining to both those questions at
http://xxx.lanl.gov, by searching under astro-ph for "cosmic ray" and
under gr-qc and hep-th for "equivalence principle".

"It usually takes one or 2 weeks for the DNA and protein molecules to organize themselves into a rigid, 3-dimensional pattern. Often they don't grow correctly, and the crystals look spindly or cracked. More often, they simply don't grow at all. No one knows why crystals grow or not, why one takes hold while all the wells around it hold small cold puddles of failure." -- p. 222, _Mapping the Next Millennium_ book by Stephens Hall.

Q: "BTW: There is some work going on on replacing the definition of the kilogram by one which does not depend on a prototype. Does anyone know the status of this?" -- Markus Kuhn, Computer Science student -- University of Erlangen, Germany http://www.cl.cam.ac.uk/~mgk25/ /* was http://wwwcip.informatik.uni-erlangen.de/user/mskuhn */

Q: Are electrons affected by gravity ?
As far as I know, every measurement of the force of gravity has been on neutral or nearly-neutral macroscopic clusters of molecules. No one has ever confirmed the common assumption that *all* of their components (ions, protons, electrons, and neutrons) are affected equally (proportional to their respective inertia) by gravity.
-- David Cary
"Another riddle is whether or not the anti-particles ... have a positive or a negative gravitational mass. It seems at first sight that this question might easily be answered by direct experiment. Just produce a beam of anti-protons ... horizontally ... and see whether under the action of terrestrial gravity it will bend down as a horizontally thrown stone or bend up... repelled by the mass of the Earth. The trouble is, however, that the anti-particles produced in our laboratories move with velocities almost equal to that of light ... Thus, if the tube is, let us say, 3 Km long, the anti-particles will pass it in the time interval of 10^-5 sec. According to the law of free fall, the will be displaced downward (or upward, in the case of negative gravitational mass) by the amount of (1/2)gt^2 ... the vertical displacement will be of the order of ... 10^-8 m, which is comparable with atomic diameter ! It is clear that no experimental arrangement can detect such a small defelection of the beam. ... one could try to slow down the anti-particle ....But how does one do it ? In the atomic piles one slows down neutrons by passing them through various "moderators" (carbon, or heavy water) where the neutrons gradually lose their energy in collisions with other atoms. But we cannot do this in the case of anti-particles, since on passing through any moderator formed by ordinary matter they will be annihilated in the very first collision. Thus the question remains unanswered. ... we do not know, and we also do not know whether or not we will ever know." -- George Gamow, in his book _Thirty Years that Shook Physics: The Story of Quantum Theory_ (1966)
(partial answer)
Einstein's General Theory of relativity appears to predict that all particles with mass (including electrons, protons, neutrons, and their respective anti-particles) are all effected equally by gravity. However, as far as I know (AFAIK), this prediction has never been confirmed. And besides, it also predicts that a beam of (massless) photons passing near a star will be bent exactly 3 times (is this right ?) the angle that a beam of particles that travels along the same path at nearly the same velocity.

Q: "If we suspend our credulity regarding UFOs, can we postulate explanations for reported violations of the conservation laws?"
-- "Jerry D. Wilson" [Date: Sun, 14 Jul 1996 ]

Q: At what speed does "gravity" travel ?
(No experimental setup has ever detected gravity waves, but even so, most physicists expect them to travel at the speed of light). (This may change soon. "Gravity wave detector all set" article by Jonathan Amos 2003-02-18 http://news.bbc.co.uk/2/hi/science/nature/2774163.stm )

Q: Assuming one has several wormholes, can you ship one wormhole *through* another wormhole ? can you ship just one end of one wormhole *through* another wormhole ? [This is necessary to implement the brilliant idea that Anders Sandberg thought up and posted to the transhuman mailing list on Date: Fri, 10 May 1996]

Q: How can a 'wormhole' be built ?

Q: I "Wonder, what a _large_ relativistic antiparticle beam weapon hit _feels_ like." -- From: Eugene Leitl [Date: Fri, 10 May 1996]

"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones."-- Albert Einstein

"Is is conceivable that a field theory permits one to understand the quantum and atomistic structure of reality ? Almost everyone will answer this question with "no." But I believe that at the present time nobody knows anything reliable about it. This is so because we cannot judge in what manner and how strongly the exclusion of singularities reduces the manifold of solutions. We do not posses any method at all to derive systematically solutions that are free of singularities. ...
From the quantum phenomena it appears to follow with certainty that a finite system of finite energy can be completely described by a finite set of numbers (quantum numbers). This does not seem to be in accordance with a continuum theory, and must lead to an attempt to find a purely algebraic theory for the description of reality. But nobody knows how to obtain the basis of such a theory."
-- _The Meaning of Relativity, 5th ed._ (1956), by Albert Einstein

Q: "Is there a more fundamental law of nature than the conservation laws (energy, Momentum, etc). Might it be some form of symmetry law?"
-- "Jerry D. Wilson" [Date: Sun, 14 Jul 1996 ]

OK, so this one doesn't really deal with an unknown, but it might still make a cool science fair exhibit:

From:  (Roland Larsson)
Newsgroups: sci.physics
Subject: Re: Help with a physics puzzle?
Date: 18 Oct 1995 15:50:52 GMT
Organization: Bartol Research Institute
Lines: 47
In-Reply-To: paassche's message of Tue, 17 Oct 1995 08:27:11 GMT

> ...  (Markus Wandel) writes:
> >I saw the following puzzle:
> >   "In a stationary bus, empty except for the driver, a helium balloon is tied
> >   to the back of a seat in the middle of the bus.  If the driver accelerates
> >   the bus to 60mph, which way will the balloon swing?"
> >I answered "toward the back of the bus" and was declared WRONG!
> >The correct answer as stated was
> >   "It would swing forward. AS the bus accelerated, air would move toward the
> >   back of the bus, increasing the density.  Since Helium is lighter than air,
> >   it would move forward."
> >
> >I'm being a sore loser here.  I am not convinced that the answer is true for
> >all cases of balloon mass and shape, bus shape, acceleration, ambient air
> >pressure, balloon gas pressure etc.
> >I know how to set up a solution, but I don't know how to solve it.
>  [... onset to real calculation omited ...]
> >I can't do this.  Can anyone else?  Is this a "classic problem"
> >with a published solution?

It is a straightforward problem to solve. (But I'm not doing it - sorry.)

A similar situation, and one that is easier to demonstrate, is the following:

Take a plastic or glass tube that is bent in a semi-circle, i.e. shaped like
a U. Fill it with water and put either a couple of wooden balls or steel balls
inside. Steel balls will obviously settle at the bottom of the semi-circle, and
wooden balls float, so they will go up to the ends of the semi-circle.

Now, start rotating the semi-circle around a vertical axis (U -> | -> U).
The steel balls will travel UP the from the bottom. The wooden balls, on the
other hand, will start to SINK from their original position at the top of the

It is a simple demonstration, but a really cool one.


Roland Larsson              |
Bartol Research Institute   |      "My brain hurts."
University of Delaware      |
Newark, DE 19716, USA       |         - Mr. Gumby

Q: Why do liquid crystal molecules align themselves with grooves in their container ? http://dvorak.mse.vt.edu/faculty/hendricks/mse4206/projects97/group06/lc.htm /* offline ? */

Q: What causes long delayed echos (LDEs), radio echos which return to the sender several seconds after a radio transmission has occurred? (In other words, long after the usual 1/7 second echo from the transmission going completely around the earth) Wikipedia: long delayed echo


see also DNA information nanotech.html#dna

Q: Is there a message (or a picture) encoded in the DNA of all living things on Earth ?

Music from DNA: music.html#DNA

Q: Are emotions hard-wired (genetic), or learned ? Does every human have exactly the same set of basic emotions ? Or do some humans have unique emotions unavailable to other humans ? What about the emotions of non-human entities ? -- 1997-03-15 paraphrase of Anders Sandberg http://www.nada.kth.se/~nv91-asa/main.html

"Good news: Oxford University scientists predict mad cow disease will die out in British cattle by 2001. Bad news: People have eaten meat products from 700 000 diseased cattle. Because the human equivalent of the disease has a 30-year incubation period, no one knows what to expect, Food Processing magazine reports." -- "Maddening news about cows for humans" article distributed by Knight-Ridder News Service, 1996 Nov 19

"Banana suppliers and health officials are trying to find out why some shoppers are getting bananas that suddenly go smelly. ... "It's like a chemical mildew, very musty, very unpleasant", Donna McLean, of suburban Colwood, said. ... The Canadian Health Department says they're edible... "Apparently it's something do to with the glue they use in the cardboard boxes," said Alex Campbell, president of Thrifty Foods chain of Victoria. Other theories suggest the bananas may pick up the smell ... from the wooden pallets used in storage." -- "Stinking bananas plague B.C.", article from the Associated Press, Victoria, British Columbia, 1996 July 2.

How do you cure (x,y,z form of) cancer ?

How do you cure the common cold ?

"In Zaire in 1979, a CDC/WHO team captured and tested several hundred animals, from mosquitos to cows, for signs of current or past infection to discover where Ebola hides between human outbreaks (to this day, no one knows)." -- _Newsweek_ May 22, 1995 p. 50.

"Time-Frequency Analysis of Heart Sounds" article by J.R.Bulgrin and B.J.Rubal, in _Scientific Computing and Automation_ 1994 Aug p. 15:

"cardiac auscultation, the art of listening to heart sounds, is still a fundamental part of the physical examination. ... heart sounds are inherently difficult to analyze ... Sounds originate from multiple sites within the four chambers of the heart, its valves and the great vessels. Perhaps surprisingly, the exact mechanism of sound production remains unknown, despite echocardiographic corroboration; e.g., the coincidence of valve closure and high frequency components in the first heart sound (1). At any rate, these acoustic signals (called phonocardiograms or PCGs) are further distorted by transmission through the chest wall, where externally attached transducers ... record the faint vibrations of the chest. Many factors, including sensor placement and body characteristics, make comparison of repeated PCGs from the same patient difficult; comparing inter-patient PCGs is even more problematic.
Despite such obstacles, physicians since the time of Laennec have learned to reliably detect a wide variety of normal and pathological heart conditions."

Q: Why are there so many different kinds of plants and animals? -- http://www.nap.edu/readingroom/books/evolution98/evol1.html . Why hasn't the one creature superior to, or equal to, all others pushed all the others to extinction, the way 3" floppies pushed 5" floppies to extinction, or 5" floppies pushed 8" floppies to extinction ?

"Workers have used DNA from bone and soft tissue to establish reliable sequences for seven extinct mammals. The oldest was the woolly mammoth -- a frozen carcass found in the permafrost of ..." -- unknown; 1995 ?

[bignums ? cloning ?] "It is thought that as many as ten million mammoths are buried in the Siberian permafrost. ... The remains of about 40 mammoths have been found in Northern Siberia and Alaska." -- unknown, 2002


Q: When a fly lands on the ceiling, does it do a half roll or a half loop? Or does it just crash into the cieling and then try to grab hold any way it can ?

A: "one thing they cannot do is fly upside-down to land on a ceiling. ... The fly approaches the ceiling rightside up, at a steep angle. Just before impact, it reaches up with its front limbs, in the manner of Superman exiting a telephone booth for takeoff. As these forelegs get a grip with claws and with the sticky, glandular hairs of the footpads, the fly swings its other legs up into position. Then it shuts down its flight motor"
-- from the article "Why God Created Flies" article by Richard Conniff, _Reader's Digest_ 1992 Jun. who in turn apparently got this information from _To Know a Fly_ book by Vincent Dethier

"A movie fools the gullible human eye into seeing continous motion by showing it a sequence of 24 still pictures a second. To fool a fly would take more than 200 frames a second." "The fly's wings beat 165 to 200 times a second." "Flies have taste buds in their feet"

More details and pictures at /* http://lpmorh04.univ-fcomte.fr/jmfriedt/flies.html offline ? */


Q: " One project I would sort of like to develop is a soliton water cannon. http://www.tinaja.com/glib/resbn63.pdf Or more correctly called a monitor or deck gun by us fire service folks. Effective firefighting streams tend to max out at 250 feet. There's lots of times when you'd want to reach a lot further. Sure enough, when you turn your garden hose on and off suddenly, an initial "packet" of water spurts much further than the steady state stream. Can you "soliton" these packets into a controllable and effective long range stream? Big bucks here. " -- Don Lancaster

Q: How many photons/second from a "typical" star are collected by a "typical" (say, 12" = 300mm) amateur telescope ? What are "good" ways of collecting these photons while avoiding other noise sources ?

Ty asks: Q: What is the ``absolute maximum UART speed with error checking and no error checking'' on the HP48 ? http://www.geocities.com/ResearchTriangle/1360/hpintrnl.html

partial A: Ty mentions that ``The HP48's ROM ... ROM routines ... ... can only transfer data through the serial port at up to 9600bps. But, using a software solution, it can transfer up to 19200bps (?) ... the IR port on the 48. Using the ROM routines, it can transfer at 2400bps, but using a software solution enables it to transfer at up to 7600bps ... RS-232 device.''

Q: What is the solution to any of the "Top 10 Hard Problems and Research Issues in Nanoelectronics" ? http://www.mitre.org/tech/nanotech/ten_challenges.html /* was http://www.mitre.org/research/nanotech/ten_challenges.html */

The X Prize (http://www.xprize.org/) $10 million cash prize that will be awarded to the first privately funded team that safely launches and lands a "reusable" vehicle to 100 kilometers altitude. Detailed rules.

Q: How do you build the 1st (nanotechnology) assembler ? (the 2nd is easy -- just feed the plans to the 1st and let it build one.).

partial A: MEMS (microelectromechanical systems) seems to be headed that direction.

partial A: "A number of ways have been proposed to create a generation zero assembler(GZA). My two favourites are by bio-engineering and MEMS. Bio-engineering would create a GZA by using proteins to manipulate atomic structure, much in the way bacteria do. You should be able to write a program in DNA to create many proteins and properly orchestrate them. MEMS (micro-electromechanical systems) are another method of creating a GZA by using what are essentially micro robots. MEMS are built by building up layers of silicon with lithography. The excess is then removed chemically to create three dimensional structures. MEMS are still a thousand times larger than assemblers but should function to build the first generation assembler." -- Toby Ben /* was http://website.lineone.net/~toby.ben */

Q: "How will we directly connect our nervous systems to the global computer ?" -- Stewart Brand, in his book _The Media Lab: Inventing the Future at MIT_ (1987) p. 264

Q: Does tweaking logic thresholds up and down help with metastability in digital logic?


Some people will pay cash for the solution of certain unsolved problems in mathematics. Eric Weisstein and Claymath list many of these unsolved problems in mathematics:

A few more unsolved mathematical problems:

Here are some more math pages you might find interesting:

Theology and Astronomy

science fair books

"simple" projects -- science fair type stuff.

SCIENCE FAIR IDEA EXCHANGE http://www.halcyon.com/sciclub/cgi-pvt/scifair/guestbook.html "Got an old and unused (but cool) idea for a science fair project? Why not ADD it here? Let someone else go wild with it! [FIXME: add this one to a "pages like this one" category: other pages with ideas for science fair projects]

Renner, Al G.Experimental fun with the yo-yo and other science projects / written and illustrated by Al G. Renner. New York : Dodd, Mead, c1979. 128 p. : ill.

How to build a better mousetrap car--and other experimental science fun / written and illustrated by Al G. Renner. New York : Dodd, Mead, c1977.128 p. : ill.

Renner, Al G."How to make and use electric motors / Al G. Renner. New York : Putnam, 1974

From: <agraps at netcom.com> (Amara Graps)
Date: Tue, 17 Oct 1995 18:51:12 GMT
Web site ("Stranger then Fiction").
See: http://www.amara.com/stranger/stranger.html
Amara Graps              email: 
Computational Physics    vita:  finger 
Multiplex Answers        URL:   http://www.amara.com/

http://www.amara.com/stranger/str_fiction.html /* was http://www.amara.com/stranger/stranger.html */

Guppies In Space

i like the "waterworlds" idea. i think it would be a really good idea to test how fish respond in space. i can understand that NASA may have better use of mass than transporting a (few) ton(s) of water for full-scale tests on salmon, but it should be no big deal to send up a plastic bag of guppies and see how they react... to the low pressure and microgravity. or have they already done that? one would think that before NASA sent up dogs and monkeys and gerbils and even people, they would have tried a few guppies. anyone have references on fish in low-pressure environments (say, high-altitude lakes?) (actually, i'd be more interested in testing the, um, pardon my ignorance of the official name, but the little scum-sucking fish that live off algae growing on the aquarium walls. it ought to be realistic model of how well catfish adapt). i suspect that fish adapt very well to space... i also suspect that an ant colony would fail miserably. -david cary

big unanswerable questions

"Big Unanswerable Questions"


Here's a sampling of the many clever tricks people have used to reduce the cost of an experiment by orders of magnitude. [FIXME: add more to list]


"why questions go unanswered" http://www.plover.com/~mjd/perl/Questions.html A very nice taxonomy of different kinds of questions, with very concrete examples of the sorts of questions that are most likely to be answered by Usenet News readers (Sometimes one can re-phrase ones question to make it more likely that someone will answer it.).

"Attaching meaning to meaningless numbers is worse than not having the numbers at all. When you lack information, it is best to know that you lack the information." -- Jeff Goldberg http://www.cranfield.ac.uk/docs/stats/

"Things Of The Non" http://world.std.com/~slur/

(1) What are the upper limits of legibility? and (2) Are there qualitative limits for excellence? -- Nicholas Fabian http://graphicdesign.miningco.com/library/weekly/aa052397.htm

Toby Ben http://website.lineone.net/~toby.ben/ has some partial answers to many questions.

Date: Fri, 26 Jun 1998 10:54:27 +0100
From: Toby Ben 
MIME-Version: 1.0
To: d.cary
Subject: Unknowns FAQ

Hi David,
I think these answers should help you. If anything needs clarification,
let me know.

Toby Ben.

>>Q: Are electrons affected by gravity?
>As far as I know, every measurement of the force of gravity has been on

>neutral or nearly-neutral macroscopic clusters of molecules. No one has

>ever confirmed the common assumption that *all* of their components
>protons, electrons, and neutrons) are affected equally (proportional to

>their respective inertia) by gravity.
In classical theory even a charged particle should be effected by
though even the charge of 1eV (electron volt) is likely to be vastly
significant than that of gravity. However, classical physics CANNOT
effects on such particles due to quantum effects. To fully answer, you
need to refer to the (unsolved) theory of quantum gravitation.

>Q:"Another riddle is whether or not the anti-particles ... have a
>or a negative gravitational mass.
Positive. I believe this has been proven. There is, however, the
of discovering negative energy matter (anti-mass) in the more exotic
of particle physics.

>Q: Does GPS need to take SR effects into account (clock offsets due to
>of satellites) ? Does GPS need to take GR effects into account
>potential of satellites)?
While SR (special relativity) or AD (autodynamics) will effect the
'local' time
of the GPS satellites, the time difference will be very small. (On the
order of
Pico-seconds). I would imagine that the satellites are periodically
updated to
correct for this.

>>Q: At what speed does "gravity" travel?
>(No experimental setup has ever detected gravity waves, but even so,
>physicists expect them to travel at the speed of light).
This depends on a number of unproven conjectures. In GR (general
gravity is viewed as a geometry of space-time with mass viewed as the
indentations in the space-time plane. In this theory, gravity will act
instantaneously over any distance.
The 'graviton', a wave like particle, has been conjectured to account
for the
loss of momentum of rotating particles(?) in a gravitational 'field'.
graviton has never been discovered and this is causing increasing
Fortunately, the theory of Autodynamics (AD) is growing in strength as a

replacement of Special Relativity (SR) and eliminates the 'mathematical
that creates the graviton'. However, if the graviton does exist, it
travel faster than light. If it did not, no graviton would be able to
from a black hole and you would not feel it's gravitational effect.
virtual gravitons?) (Unless the graviton has a way of escaping

>Q:How do you build the 1st (nanotechnology) assembler ?
>(the 2nd is easy -- just feed the plans to the 1st and let it build
A number of ways have been proposed to create a generation zero
My two favourites are by bio-engineering and MEMS. Bio-engineering would
a GZA by using proteins to manipulate atomic structure, much in the way
bacteria do.
You should be able to write a program in DNA to create many proteins and
orchestrate them.
MEMS (micro-electromechanical systems) are another method of creating a
GZA by
using what are essentially micro robots. MEMS are built by building up
layers of silicon
with lithography. The excess is then removed chemically to create three
structures. MEMS are still a thousand times larger than assemblers but
should function
to build the first generation assembler.

Toby Ben 
"Innovation is hard to schedule."
http://website.lineone.net/~toby.ben (PGP Key available)

Planetary Mysteries http://www.dnai.com/~planmyst/ ??

Q: When you hold your thumb over a flashlight in a dark room, it glows red. Why ? Obviously the light isn't shooting directly through, or you would see the shadow of your bone. -- Paul Cary

Date: Thu, 19 Mar 1998 01:25:00 -0800 (PST)
From: Robert Freitas 
To: d.cary
Subject: Your Website and Recent Posting
MIME-Version: 1.0


I saw your recent posting on "Microscopic 3-D imaging in materials":

> A team of Los Alamos National Laboratory and Caltech scientists have developed a new technique that marries two existing technologies to probe materials at a microscopic level. > The device combines magnetic resonance imaging (MRI) and atomic force microscopy (AFM) ... The researchers have called the new approach "magnetic resonance force microscopy". ... their ultimate goal is to be able to create three-dimensional images of materials in slices as small as one atom wide.

I checked your web page and was unable to find any more information on this. Could you possibly email me the "longer version" of this news item (including its URL source?), which hopefully contains more technical details, so I could check it out?

Magnetic force and most importantly magnetic energy density don't scale well, e.g. down to the nanoscale, so I assume that to reach "one atom wide" resolution using MRI (to penetrate below the topmost layer that the AFM can image directly), some relatively large >micron-scale or >millimeter-scale system will be required. Or are these people proposing that a complete sensor system on the order of 10-1000 nm in characteristic size can in theory be employed to achieve the "one atom wide" MRI resolution? If so, I will be very interested and will want to know more! Thanks for your help!

On another matter, I checked out your website and found it to be quite stimulating. Thanks for putting together such a nice collection of interesting stuff.

BTW, I might recommend that you add to your "Robotics links" the following reference:


This will give your list some coverage in the area of self-replicating machines, which happens to be my favorite area of interest in robotics. You might also want to add some of the links from my NASA work (that appear on moshes' page) explicitly to your own site, such as Merkle's URL describing the 1980 NASA Study which I edited. I think you might this material interesting. :>)

I tried your link to the Flying Robots URL (given below) and it appears to be dead (though it's possible my system was just acting up for no good reason, as it does sometimes):


I also checked out your "Unknowns" page. Under Physics, regarding the thumb over the flashlight that glows red, I'm quite mystified as to what is supposed to be unknown here.

It is fairly well-known that the mean free path of a photon in soft human tissue is 10-100 microns, "depending...". Thus in typical soft tissue, after ~150 microns some 99% of all photons have suffered at least one scattering event. By contrast, the cha racteristic range for absorption in typical human soft tissue is on the order of a few millimeters. So what you're seeing coming through your thumb is photons that have been scattered many many times, but have not yet been absorbed by the tissue. That's why you get a generalized diffuse glow rather than a sharp image showing internal structures like an x-ray. (Blue is preferentially absorbed, which is why the glow appears red.)

It may interest you to know that transillumination is being actively investigated as a way to look for subdermal tumor masses noninvasively. They use extremely fast flashes and various shutter-timing tricks to filter out the scattered photons, so that their sensors can preferentially accumulate those exceedingly few "ballistic photons" that have not yet been scattered, and which therefore still contain useful information about absorbers (e.g. bones, dense tumor masses, etc.) lying in the beam path.

There's tons of literature references on all this stuff -- it's really quite "old hat"!

Also in your "Unknown" file, regarding whether antiparticles fall in a gravity field, I'm really sorry that I can't recall where I read this, but it seems to me that I saw that this had been experimentally verified, sometime in the last few years. You might try a literature search down at the library -- you might come up with the reference that I've unfortunately forgotten.

Your Unknown entry "How do you cure the common cold" is somewhat uninspiring, given that Agouron Pharmaceutical has an enzyme inhibitor drug that prevents cold viruses from reproducing, thus "curing the comon cold," that is going into clinical trials this year and should be on the market by 1999. Gilead Sciences also has an experimental drug for flu, which has eliminated all flu symptoms in experiments on ferrets but is still a few years away from hitting the market. Still, we should enter the new century (e.g. ~2001) with both cold and flu essentially "cured".

As for "how do you cure cancer", some cancers already can be, and antitelomerase (and many other biotech) therapies undoubtedly can cure many more, but our surest bet it to use nanomedical devices, which will probably start becoming available in ~20 years . I'm currently writing a book on this very subject! :>)

Robert A. Freitas Jr.

"The ugly fact is that we haven't a shred of evidence that morality in humans did or did not evolve by natural selection. We do not even know what such evidence would look like. We can, if we like, construct plausible adaptive scenarios ("What would happen to a gene that said be nice to strangers if . . ."). But, in the end, a thought experiment is not an experiment. We have no data." -- H. Allen Orr http://www-polisci.mit.edu/bostonreview/br21.3/Orr.html

"Why don't they make ..." http://www.altavista.com/cgi-bin/query?pg=q&text=yes&kl=XX&q=%22Why+don%27t+they+make%22&act=search search on AltaVista.

Q: Ok, explain this Fnord thing http://www.odyssee.net/~fnord/mfnord.html A: unexplainable. Possibly humor.

"information prizes For more on information prizes in general, check out Robin Hanson's "Work in Progress," and "Publications" pages." [FIXME: what is the URI ?]

"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." -- Charles Darwin

http://www.lastrega.com/Hasslberger/awa.htm Buckminster Fuller ???

Society of Amateur Scientists http://www.sas.org/

Santa Barbara Science http://www.west.net/~science/ "an educational consulting and mail order organization providing technical information and resources to the homeschooling, hobbyist and art communities." seems like it has some nice Science Fair resources. Check out the "GIANT AIR CANNON" used to produce "Giant Smoke Rings". OK, so maybe it's only about a one foot cube.

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