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      APRIL 96 
The Armchair Scientist
Lo Scienziato in Poltrona
Science & Technology Magazine by Loris Crudeli
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Doing Science being comfortably seated in your own armchair,
keeping up with the most advanced researches, sharing
your work with scientists everywhere in the world,
exchanging ideas, theories, challenges.
A new way to be a "global" scientist-philosopher.
...and don't forget that Science is also curiosity, wonder and fun!
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     Cover Story


THE PRIVATE WORLD
OF GRANULAR MATERIALS

Granular materials are very common in everyday life: salt, sugar, coffee, talc powder, sand, coal. They are made of common substances but in some way their behavior is completely different from what we can see in homogeneous gases, liquids or solids. The sensitivity to temperature is what matters in this different behavior. You must think about granular materials as a "substance" whose "atoms" are the grains themselves, zillion of times heavier and bigger than the atoms or molecules which form the standard substances. In the case of atoms and molecules the temperature we normally live in will give so much energy to each minute building block that it is possible that it will be displaced from its neighbors: below zero Celsius degrees the molecules of water are strongly tied together, above zero the molecules roam free and water is liquid. In the case of a pile of sand the energy required to move one grain from the others is one million million times higher than what can be produced by thermal effects alone: the sand will be converted to a solar plasma before the temperature can be high enough to "move" the grains! From this simple fact come a lot of interesting implications which have been explored by several scientists:

Paul Umbanhowar (Texas) described an experiment at last month's American Physical Society (APS) meeting in St. Louis, in which the effects of air between the grains and the interaction between the grains and the walls were minimized by using a wide, shallow container. When the grain sample is vibrated, numerous patterns form: stripes, hexagons, and baseball stitches. When the layer thickness is of exactly 17 particles, novel localized structures appear. According to Umbanhowar, these "oscillons" are like ripples in a pond but with an important difference; they do not spread out and they can form bound states.

In the April issue of Physics Today the authors Heinrich Jaeger, Sidney Nagel, and Robert Behringer explain: Consider sand contained in a tall cylinder. The pressure in the cylinder does not increase indefinitely with depth, as it does in ordinary fluids. Rather, the pressure does not exceed a certain maximum value because the contact forces between grains and friction between grains and the walls cause part of the weight of the overlaying material to be imparted to the walls. Another property which sets granular materials apart from other fluids is the tendency (in a vibrated tank containing particles of differing sizes) for the larger objects to float to the top regardless of their density. Part of the reason for this is that the smaller particles fall into the voids between the larger particles, making it difficult for the larger ones to move downwards (especially along the walls) as part of a convective flow.

The properties of granular media in technological issues is clear, as in packaging, mixing, sifting, mining, and erosion processes, but the universe itself may exhibit a sort of granular arrangement. One simulation of granular gases involving a large sample of inelastically interacting hard disks resulted in the "inelastic collapse" of the system into a foam of chainlike structures roughly resembling the distribution of galaxies in the cosmos. The Physics Today authors speculate that the role of gravity in shepherding galaxies may be analogous to the role played by container walls in shaping granular fluids into clusters. At the cosmological level, the "grains" would be stars and galaxies.


more info in APS document: Pattern Formation in Vibrated Granular Layers

 
 
 


The Highlights of this Issue:
Personal Area Network, intra-body communications.
Revolution in Particle Physics Research
"Beyond Einstein" by David de Hilster, (Autodynamics)
New Scientist - Planet Science: enter Goliath!
Space-Time-Information, a meeting on information technologies

 
 
 

  

INDEX

"If a man cannot describe a concept simply, no matter how complex the subject,
then he does not really understand it"  (C. A. Jorgenson)


From the Editor: Easter Egg Surprise! 

Did you think that The Armchair Scientist was stuck to the December issue? Well, almost, but now here it is with this rich issue coming out exactly on the Easter day, which should be a hint about the rush I made to prepare it!

The Armchair Scientist: a Proposal
This new e-magazine has two goals: to present scientific results and achievements in an attractive and unimposing way and, at the same time, to stimulate the quest for a new way to do science in spite of the deluge of information going on in our society.

Instructions for Readers and Contributors: 
The interface between the magazine, the readers and the contributors, making it easy to interact by following short and easy procedures. It should be improved with your help. For writing down your comments while reading the magazine please open the icon on the right holding down the mouse button and selecting the option "open in a New Window".

Auto-Alert for Next Issue    ARMCHAIR-SCIENCE mail-list
mirror at Video On Line      versione italiana
 

 

The Science Show 
Enjoy the results of scientific endeavor of scientists and researchers from every part of the world! Here you can find amazing news, astonishing images, curiosities that surpass fantasy and even science-fiction:

The first direct image of the surface of a star
Deepest-ever view of the Universe
Tether physics explained
Scanning Tunneling Microscopy: Quantum Corrals
Angry debate on Nanotechnology: Ralph Merkle vs. SciAm
Preliminary data from Galileo probe
and more:  The earth slowed down by Galileo probe! - Cyberaddicts - The Visible Woman on the Web - Cold Fusion in Italian Court - Did neutrinos kill the dynosaurs? - 10000 tons of interplanetary dust particles -
 

 

The Technology Show 
My personal pick from the most advanced and less known developments in technology, industrial processes, materials, inventions:

Personal Area Networks (intra-body communications)
Earth-To-Orbit Transportation (28 methods!)
Advanced Photo System (revolution in photography)
Don't catch that plane! (danger from software chaos)
and more:  Micromachined ultrasonic transducers - Planar display expands viewing area - Revolutionary X-Ray instrument - DVDs, next generation of laser disks - White House plans for HDTV - Computer companies against digital TV standard
 

 

Heavy Science 
This section contains articles and news for the more specialized and technical reader and can be skipped by the casual visitor. Science is made of this stuff and the beautiful results of the two previous sections are possible only after much effort in this difficult territory:

Revolutionary advancements in particle physics research:
Tabletop laser accelerators - Crystal beam deflectors for 900 GeV particles - The first X-Ray hologram with atomic resolution
Zoom in on atoms and molecules:
Sensing technique sheds light on atomic motion - Single molecule biosensors
Why water shrinks when warmed?
 

 

New Theories
Science can proceed only if new theories are imagined, proposed, discussed. Many of them will be wrong, based on wrong assumption, flawed in the logic, or just crack pot ideas. But honestly we have no choice other than considering them all and give them a chance:

In this issue a very clearly written article, "Beyond Einstein" by David de Hilster, will introduce you to Autodynamics.
 
 
 

DEPARTMENTS


FORUM: mail, announcements 
After the second issue the mail reached an alarming level, and it took a big part of my time to answer and process all the readers' messages. Some of them are reproduced here, as they can be of general interest.

Auto-Alert for Next Issue    ARMCHAIR-SCIENCE mail-list

 

Sharing Knowledge 
Being an active participant in the scientific arena is much easier today if you become familiar with the thousands of Scientific Net Resources: newsgroups and mail-lists, e-magazines and e-bulletins, whole books and manuals, data bases, associations...

e-magazine: New Scientist - Planet Science
mail-list: Popper - Philosophy of Science
mail-list: Debono - Lateral Thinking
mail-list: Inventors - Ideas Development and Patenting
resources: My Virtual Encyclopedia - Virtual Facts
resources: Fractal Zoom, Eloisa-Virtual Personality, Virtual Geomorphology

 

The Treasure Chest
Here you can find the index of old issues so that you can easily search for old material or useful references. You can browse them online or, if you prefer, you can download any one of them as a single zipped file that you can read at leisure offline, from your hard disk.
Events
A listing of the major science and technology events and announcements, things to do, places to go...

conference: Space Time Information
conference: Intelligent User Interfaces
seminar: Human Science Research

 

Web Links...
For the people who are not satisfied with all the above and prefer to dive personally into the cyberspace...at their own risk!

Use this Altavista-Digital Search Form to search the Web and the Newsgroups with a minimum of effort and at amazing high speed.
 
 
 

CONTRIBUTIONS

David de Hilster - the article "Beyond Einstein - Autodynamics"

Andrew Nowicki - the article "Earth-To-Orbit Transportation Bibliography"
Gianpiero Ruggiero - conversion of .ZIP files of old issues to MS-DOS/Windows format
Zbigniew Zwolinski - Virtual Geomorphology
Niels Ulrik Reinwal - fractal exploration program
Francesco Lentini - new version of Eloisa Online
Roberto Giambrocono - translation of article "Eloisa, Virtual Personality", (issue 2)
Marco Canonico, Rossella Gigli,
Michael Delceg, Andrea Peyracchia,
Fabio Fertig, Pietro Terna,
Antonio Trincone, Bob Starr
Philip Gibbs - suggested lots of interesting URLs


Following the collaborative spirit of Internet I hope that some of you readers, scientists, philosophers, amateurs, will be interested enough to start helping "The Armchair Scientist" in any way you can think of. Everybody is welcome and I invite all of you to take an active part in the game. Obviously all published material will be credited to its original author. Remember that if everybody gives a little all of us will receive a lot!
Instructions for Readers and Contributors: 


 
 
 
 Note: while reading this magazine you can use the armchair icon to come back to this Cover Page, and the page icon to return to the last used Index, in a hyerarchical way.
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The Armchair Scientist - 7 April 1996
Copyright 1996   by   Loris Crudeli
Send comments and material to: [email protected]
https://www.areacom.it/html/arte_cultura/loris/armchair.html
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