Busy
>> Tuesday, September 04, 2007
Haven't posted in a while which is usually a sign of me being way too busy......
A science blog. If you are interested in learning, watch them. If you want to argue about them, go ahead.
Haven't posted in a while which is usually a sign of me being way too busy......
Read more...People who knew physics and Einstein surely heard about "Michelson–Morley experiment" was performed in 1887 by Albert Michelson and Edward Morley. Here is a doubt going through my mind.
Take first letters of both the above mentioned scientist i.e., A E, similiarly Albert Einstein's name can be written like this A E, is it coincidence?
To add 1 to 100 numbers use Equation :[n(n+1)]/2
Ex> for 1 to 100 (100*(100+1))/2 = 5050.
nikola tesla the philadephia experiment Time travel film interview patents inventions producer carlos diaz xfactor.
Is time travel possible? In this fascinating short documentary, director Jay Cheel explores the real-life theories behind the science of ... all » time travel and the strange subculture of enthusiasts who are obessed with it. Meet Michio Kaku, world-renowned theoretical physicist and author of the book Hyperspace. Meet Rob Niosi, a hobbyist building his own full-scale home replica of H.G. Wells' time machine. Meet Larry Haber, the entertainment lawyer representing the family of John Titor, an alleged time traveller from the year 2036. Do these people know something about the world that the rest of us don't? Obessed & Scientific is a quirky look at the intersection of science-fact and science-fiction. Visit www.thedocumentaryblog.com for more information, or email me at jcheel@sympatico.ca.
A documentary based on the work of Harun Yahya.
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The Roswell UFO incident involved the recovery of materials near Roswell, New Mexico, in July 1947, which have since become the subject of intense speculation and research. There are widely divergent views on what actually happened, and passionate debate about what evidence can be believed. The United States military maintains that what was recovered was a top-secret research balloon that had crashed. However, many UFO proponents believe the wreckage was of a crashed alien craft and that the military covered up the craft's recovery.
VISIT: http://www.soulcravings.net for more vids
1. 1st Part
2. 2nd Part
3. 3rd Part
4. 4th Part
5. 5th Part
Will the Large Hadron Collider finally reveal the elusive God particle?
There's a supermassive black hole (up to a billion times the mass of a usual black hole) in the center of every galaxy. It's linked to the creation of the galaxy itself.
This is a small footage of a wonderful show called "Horizon" and it's a co-production of the BBC and Discovery.. There is still much more to learn in the actual documentary.
I strongly suggest that you visit http://www.bbcworld.com to find out about their extraordinary programme. It amazes me day after day.
To see documentory click here.
A journey of simulations of Black Holes, Neutron Stars, White Dwarfs and Space and Time. Though, it is only a simulation, nothing more.
The simulacrum is never that which conceals the truth--it is the truth which conceals that there is none.
The simulacrum is true.
Ecclesiastes
Hawkings reverses his 30 year old theory that black holes destroy matter, and seeks to show convincingly that alternate universes exist without black holes. Again, God's ways are past finding out.
Stephen Hawking gives a lecture on the Hawking-Hartle no boundary universe.
Lecture given to a sold out crowd at the Berkeley on March 13 2007.
http://www.pbs.org/wnet/hawking/universes/html/bound.html
A Brief History of Time was more than a best seller. In it, Hawking parted from the conventions of natural science to write in a more stylistic unfettered manner: dramatic, poetic and prophetic. "At the big bang and other singularities, all the laws would have broken down, so God would still have had complete freedom to choose what happened and how the universe began." Anecdotal trivialities? Perhaps not. Hawking is a performance artist.
Prof. Stephen Hawking is interviewed on Israeli TV show hosted by Yair Lapid. He answers (sort of) the question: does he believe in God?
The basic assumption of science is scientific determinsim. The laws of science determine the evolution of the universe, given its state at one time. These laws may, or may not have been decreed by God, but he cannot intervene to break the laws or they would not be laws. That leaves God with the freedom to choose the initial state of the universe, but ?as in here? it seems there may be laws, so God would have no freedom at all.
So he belives in God, but believes he has doing nothing in creation of everything?
Hawkings reverses his 30 year old theory that black holes destroy matter, and seeks to show convincingly that alternate universes exist without black holes. Again, God's ways are past finding out.
Is there a theory that will encompass everything in the known universe? Inflation theory, quantum mechanics, string theory.
Its in tresting but all just evidence coming of predictions we have no real way of noing how it all started, ie the big bang all or most of this is not fact its just what the conclusion we get to from are very very limited factual knoledge, the universe is expanding so it seems but how can we no that if we cant see the edge if there is 1 of the universe, we know **** all, and quatum mechanics is a step to far into making it up as we go along.
Are black holes infinitely small "holes" with a large magnetic field that make them appear large or are they giant black spherical stars?
They are like a black spherical stars. In the center is the infinitely small region known as a gravitational singularity.
I have trouble myself understanding singularities but I'm working on it.
Imagine the tip of hair with a mass of the entire universe. A BH's shape is something weird than that. In fact, one cannt imagine that point, which is called singularity, where all the laws of physics fail. But what defines the 'shape' of BH is the event horizon, beyond which the BH starts to grab things, even the light and magnetic field. In other words the starting point of gravitational influence.
Are black holes real? Ultraluminous quasars and supermassive black holes, wormholes, and singularities.
What is the destiny of the universe? Dark matter, WIMPS, MACHOS, neutrinos.
What is the universe and everything in it made of? The creation of matter, the building up of elements in stars.
Where did we come from? The history of cosmology from flat earth to Big Bang: Eratosthenes and Ptolemy, Copernicus, Kepler, Galileo, Newton, Edwin Hubble.
Did the universe have a beginning? The Steady-State theory vs. The Big Bang, Albert Einstein, Georges Lemaître, Fred Hoyle, Arno Penzias and Robert Wilson, cosmic background radiation.
Why do we do science? Beyond altruistic and self-aggrandizing motivations, many of our best scientists work long hours seeking the electric thrill that comes only from learning something that nobody knew before. The Pleasure of Finding Things Out, a collection of previously unpublished or difficult-to-find short works by maverick physicist Richard Feynman, takes its title from his own answer. From TV interview transcripts to his acceptance speech for the Nobel Prize, we see his quick, sharp wit, his devotion to his work, and his unwillingness to bow to social pressure or convention. It's no wonder he was only grudgingly admired by the establishment during his lifetime--read his "Minority Report to the Space Shuttle Challenger Inquiry" to see him blowing off political considerations as impediments to finding the truth.
Richard P. Feynman (1918-1988), scientist, teacher, raconteur, and musician. He assisted in the development of the atomic bomb, expanded the understanding of quantum electrodynamics, translated Mayan hieroglyphics, and cut to the heart of the Challenger disaster. But beyond all of that, Richard Feynman was a unique and multi-faceted individual.
THE PLEASURE OF FINDING THINGS OUT was filmed in 1981 and will delight and inspire anyone who would like to share something of the joys of scientific discovery. Feynman is a master storyteller, and his tales -- about childhood, Los Alamos and the Bomb, or how he won a Nobel Prize -- are a vivid and entertaining insight into the mind of a great scientist at work and play. visit: http://www.soulcravings.net for more vids
BUY THE DVD: http://www.sykes.easynet.co.uk/pofto....
Why do we do science? Beyond altruistic and self-aggrandizing motivations, many of our best scientists work long hours seeking the electric thrill that comes only from learning something that nobody knew before. The Pleasure of Finding Things Out, a collection of previously unpublished or difficult-to-find short works by maverick physicist Richard Feynman, takes its title from his own answer. From TV interview transcripts to his acceptance speech for the Nobel Prize, we see his quick, sharp wit, his devotion to his work, and his unwillingness to bow to social pressure or convention. It's no wonder he was only grudgingly admired by the establishment during his lifetime--read his "Minority Report to the Space Shuttle Challenger Inquiry" to see him blowing off political considerations as impediments to finding the truth.
Richard P. Feynman (1918-1988), scientist, teacher, raconteur, and musician. He assisted in the development of the atomic bomb, expanded the understanding of quantum electrodynamics, translated Mayan hieroglyphics, and cut to the heart of the Challenger disaster. But beyond all of that, Richard Feynman was a unique and multi-faceted individual.
THE PLEASURE OF FINDING THINGS OUT was filmed in 1981 and will delight and inspire anyone who would like to share something of the joys of scientific discovery. Feynman is a master storyteller, and his tales -- about childhood, Los Alamos and the Bomb, or how he won a Nobel Prize -- are a vivid and entertaining insight into the mind of a great scientist at work and play. visit: http://www.soulcravings.net for more vids
BUY THE DVD: http://www.sykes.easynet.co.uk/pofto....
What do bicycle wheels, figure skaters, and exploding stars have in common? That’s right, angular momentum. This video quotes three others: Rotating Person and Bicycle Wheel, Skating: Scratch Spin, and Exploding Neutron Star.
Read more...Transcript: http://www.davidcolarusso.com/edblog/...
This video is an adaptation of an earlier piece of mine--Perspective on quantum mechanical tunneling. That film, however, was designed for a unique audience, and I felt its overall length was limiting its appeal here. So I've repackaged it as one of my weekly postings. I Hope you enjoy.
People have been asking for the math. So here it is. The Sun's core temp is ~13.6 MK. For hydrogen nuclei the Coulomb barrier is roughly 0.1 MeV. This corresponds to a temperature in excess of 1 GK! Luckily, tunneling and the distribution of speeds among nuclei lower the actual temperature required. So without tunneling even the Sun's core isn't hot enough for fusion. To see most of this worked through, check out this link:
http://burro.cwru.edu/Academics/Astr2...
for a less mathematical explanation, try:
http://en.wikipedia.org/wiki/Nuclear_...
The Tabletop Explainer is a quasi-weekly series answering science questions and presenting brief lessons and ideas for teachers and students. If you have any comments, move the discussion to my blog, "On Education" http://www.davidcolarusso.com/edblog/
Update: People have been asking for the math. So here it is. The Sun’s core temp is ~13.6 MK. For hydrogen nuclei the Coulomb barrier is roughly 0.1 MeV. This corresponds to a temperature in excess of 1 GK! Luckily, tunneling and the distribution of speeds among nuclei lower the actual temperature required. So without tunneling even the Sun’s core isn’t hot enough for fusion. To see most of this worked through, check out this link:
http://burro.cwru.edu/Academics/Astr221/StarPhys/coulomb.html
for a less mathematical explanation, try:
http://en.wikipedia.org/wiki/Nuclear_fusion#Requirements
Transcript:
The Tabletop Explainer
Episode Six (6)
What is quantum tunneling?
Some of us were taught in high school that the electron orbits around the nucleus like a planet around the sun. However, this description has been understood as a gross mis-representation for the better part of the last century. As it turns out, there is a characteristic uncertainty related to the very small. No one can tell exactly where something is; the best one can do is figure out where something is most likely to be. We can visualize this with something called a probability cloud. Here we see the probability cloud of a proton at the center of a hydrogen atom. The denser regions are where the proton is more likely to be found. However, this uncertainty is not due to an inability of ours to measure the small in an exact manner; it is a fundamental aspect of the world in which we live, and its implications are extraordinary.
Let us take for example the phenomenon of tunneling. If we can’t tell exactly where something is then it follows that we can’t tell exactly where it’s been or where it will be. The best we can hope for is where it most probably will be. So there’s a small chance that a racket ball thrown repeatedly at a barrier could just tunnel through the barrier, appearing almost magically on the other side. We don’t see this often because a racket ball’s pretty big and its uncertainty pretty small. But if we deal with matter on the subatomic scale it becomes much more likely. Here our projectile approaches the barrier, we see here its probability cloud, although it’s most likely near the center of the cloud we can see that there is a small chance of it being on the other side of the barrier, and so sometimes it is. Tunneling isn’t a mathematical trick or an assumption, it’s an observable fact. It’s made use of commonly in modern electronics and in a real way allows for life on earth. To see why, let us trace the creation of a photon in the sun. The light from the sun that we see reflected off the moon, the light which drives the earth’s weather, that provides the energy for life all originates from the process of nuclear fusion in the sun. Two light atomic nuclei collide, forming a new element, and in the process light is released. But these nuclei are both positively charged and so repel each other. Only if they have enough energy can they overcome this potential barrier and fuse. But if you do the math, the nuclei in the sun don’t have enough energy. The sun’s just not hot enough, non the less, the sun shines, and it does so because of tunneling. Just like our physical barrier, there’s a chance that our particle could be on the other side, and so the sun shines.
[roll credits]
What do you think?
This piece was designed to get you thinking. So find a physicist and get talking, or post a comment and get a discussion going. The main point is that quantum mechanics is real because it properly describes nature. Einstein may have believed that God doesn’t play dice, but God need not conform to Einstein’s beliefs.
Physicist York Dobyns of Princeton University talks about how the future intentions may affect the past at the American Association for the Advancement of Science at University of San Diego on June 23, 2006. Interview by Tom Munnecke.
He discusses some of the ideas of Cal Tech Physicist Kip Thorne's theories of wormholes on the fabric of space and time. He also discusses some of the strange implications of our understanding of quantum mechanics.
This is interesting in the context of designing the Good Ancestor Principle in the context of the Uplift Academy.
York Dobyns earned his PhD in physics at Princeton and is now with the Princeton Engineering Anomalies Laboratory http://www.princeton.edu/~pear/
The entire film is called "What the bleep do we know", googlevideo it. This is revolutionary in the truest sense of the word;Intelligent Design, Dimensions, Time Travel, Life after death, a conscious growing Gaia,Law of Attraction etc. etc. are a lot easier to accept if you at least consider whats being said in this film about Quantum Physics.
Clips from a BBC documentary explaining the arguments from the 1920's until now as to whether electrons are particles, waves or both.
It outlines Einstein's distaste at Heisenberg's uncertainty principle and is a good starting point in realising that the universe is far, far stranger than can be imagined.
Also has some interesting footage showing the impact that the pursuit of quantum physics has made to our world today.
Richard Dawkins explains why Quantum Theory must be right even though it is unintelligible! For more videos explaining unexplainable Quantum Theory ;-) and its implications, see http://www.yoism.org/?q=node/167 (you can also download this video there). For more "Saint" Richard ;-) check this out: http://www.yoism.org/?q=node/99
Since nature is probablistic and yet somehow is favorable toward the evolution of more complex and ordered assemblies...God may in fact "play dice with the universe" but it seems to me that they are loaded.
The real footage of the Hiroshima bomb going off...
Mind you that this was not a test.
LITTLE BOY (August 6 , 1945 08:15am)
15 KILOTONS
This video contains clips from "Trinity And Beyond" Directed By Peter Kuran.
The real footage of the Nagasaki bomb going off...Mind you that this was not a test
FAT MAN (August 9 , 1945 11:02am)
20 KILOTONS
The atomic bombings of Hiroshima and Nagasaki involved a nuclear attack during World War II against the Empire of Japan by the United States. On August 6, 1945, the nuclear weapon "Little Boy" was dropped on the city of Hiroshima, followed on August 9, 1945 by the detonation of the "Fat Man" bomb over Nagasaki,killing tens of thousands of children and elderly,injured tens of thousands of people who died months or years after the bombing as a result of radiation exposure.
Double Nobel Prize Winner Dr. Linus Pauling discusses his petition against nuclear testing and calls for an end to war.
Feynman(books to read)
1. Feynman Lectures on Physics
2. SURELY YOU'RE JOKING MR FEYNMAN
3. Pleasure of Finding things out.
4. Feynman's Lost Lecture
5. What do you care what other people think?
This should be the first lecture for all the physics courses.If more people understood this simple 17 second clip, there would be a substantial reduction in the religiously fueled atrocious wars and murders and that have stained the history of man with bloodshed, and yet we must be selectively colorblind for we as a species continue on this path to this day.
Other links on the same views can be obtained on this blog. Its named Pale Blue Dot. or you can watch it here.
A short story about tells about him calculating equations in his head and baffling mathematicians and it was a fascinating read.He was really a genius.
Feynman's articulation with regard to his opinion of honor's is not just for scientists since it transcends all endeavors mankind are capable of pursuing.
"Honors aren't real" ... now that's a real man talking. He's so genuine, so honest, so himself, so real... Bravo to a great human being who continues to inspire others.
This is a Horizon video from 1981 made for the BBC. It features an interview with one of the greatest physicists of the 20th century.
For more information see: www.sykes.easynet.co.uk/pofto.html
BBC interview of Feynman.
Richard Feynman on the rational scientific method; increments and revolutions and castling.
Fenman's views on The difference between knowledge and deep understanding.
Feynman Playing his favorite drum.
Short film on Richard Feynman's famous quip about fundamental physics as seen via quantum mechanics. Touches upon Einstein's E=MC2, Newton's law of gravity and the motion of planets, and the future of science.
More clips from the Interview @ http://www.bbc.co.uk/sn/tvradio/progr...
Richard Feynman on the appreciation of nature. Video is from 1981 BBC Interview. The interview is also the subject of Feynman's book The Pleasure of Finding Things Out.
I have a friend who's an artist and he's some times taken a view which I don't agree with very well. He'll hold up a flower and say, "look how beautiful it is," and I'll agree, I think. And he says, "you see, I as an artist can see how beautiful this is, but you as a scientist, oh, take this all apart and it becomes a dull thing." And I think he's kind of nutty.
First of all, the beauty that he sees is available to other people and to me, too, I believe, although I might not be quite as refined aesthetically as he is. But I can appreciate the beauty of a flower.
At the same time, I see much more about the flower that he sees. I could imagine the cells in there, the complicated actions inside which also have a beauty. I mean, it's not just beauty at this dimension of one centimeter: there is also beauty at a smaller dimension, the inner structure...also the processes.
The fact that the colors in the flower are evolved in order to attract insects to pollinate it is interesting -- it means that insects can see the color.
It adds a question -- does this aesthetic sense also exist in the lower forms that are...why is it aesthetic, all kinds of interesting questions which a science knowledge only adds to the excitement and mystery and the awe of a flower.
It only adds. I don't understand how it subtracts.
Richard Feynman on the electromagnetic spectrum.
"But you gotta stop and think about it ... to really get the pleasure about the complexity; the inconceivable nature of nature"
http://en.wikipedia.org/wiki/Electrom...
a second or third gen PAL VHS dub of a vintage original off-air NTSC VHS tape, then captured and compressed and found on a torrent site. squashed, re-compressed and converted for YouTube. all sorts of obvious video and audio problems, but at least it's here, a special treat from the past. anyone with better source, please drop a comment.
in the meantime, point your 1/8" black-holes at this nice piece of tape of The Chief.
edited by Brant Penman. voiceover by Loren Penman and Aaron Joy
Thomas Edison shares his philosophy on money and work. Although portrayed by actor, Frank Attwood, these are Edison's words.
Take a look at it :
http://www.youtube.com/watch?v=M97WgCkK6k4
Are we alone? This is the question yet to be answered by scientists.
Here is the Earth seen from four billion miles away. The Earth is a dot suspended in a beam of sunlight (pinpointed by artificial blue circle). Check out Wikipedia’s article about the Pale Blue Dot.
On February 14th, 1990 the Voyager I spacecraft turned around and took the now famous “Pale Blue Dot” picture. The spacecraft, at the time, was about 4 billion millions away when it it took the picture. This was the first time man ever saw our Earth from this vantage point.
The Voyager spacecrafts (both I and II) also carry a “golden record”. This record contains images and sounds that were selected to portray the diversity of life and culture on Earth. Space being so vast, I will take about 40,000 years to come near another star. I do however think it is interesting that a part of us is floating out in space.
The contents of the record were selected by Carl Sagan. They picked out 115 pictures and a variety of sounds such as wind, animal sounds, and thunder. They also added musical selections from different cultures and eras, and spoken greetings from in 55 languages. President Jimmy Carter was also asked to include a message. Below is the message he included on the record.
We cast this message into the cosmos… Of the 200 billion stars in the Milky Way galaxy, some — perhaps many — may have inhabited planets and space faring civilizations. If one such civilization intercepts Voyager and can understand these recorded contents, here is our message: We are trying to survive our time so we may live into yours. We hope some day, having solved the problems we face, to join a community of Galactic Civilizations. This record represents our hope and our determination and our goodwill in a vast and awesome universe.
The included list of languages is as followed
* Akkadian, Amoy (dialect of Min Nan), Arabic, Aramaic, Armenian
* Bengali, Burmese, Cantonese, Czech, Dutch, English, French, German
* Ancient Greek, Gujarati, Hebrew, Hindi, Hittite, Hungarian, Ila (Zambia)
* Indonesian, Italian, Japanese, Kannada, Korean, Latin, Luganda, Mandarin Chinese
* Marathi, Nepali, Nguni, Nyanja, Oriya, Persian, Polish, Portuguese, Punjabi
* Quechua, Rajasthani, Romanian, Russian, Serbian, Sinhalese, Sotho, Spanish, Sumerian
* Swedish, Telugu, Thai, Turkish, Ukrainian, Urdu, Vietnamese, Welsh, and Wu
High altitude vehicles and nanosattellites are routinely used for reconnaissance and communication applications and the launch of such aerospace vehicles require rockets with advanced propulsion concepts. The cost of launching these spy satellites and airships by conventional rocket technology remains very high.
Technically, despite four decades of propulsion development, there have been no spectacular improvements in the energy density of propellant materials because the Isp* of any chemical propellant is limited by the energy of chemical bonds that are broken. The highest Isp possible (H2/O2 reaction) is only 460 seconds. Consequently, the price of launch has hovered around $10,000 per kilogram of payload delivered to low earth orbit. On the economic end, market models predict an essentially flat elasticity of demand for space launch until the payload cost is reduced below $1000 per kilogram[i].
There are two ways to increase the Isp of the propellant past the practical chemical limit of 460 seconds:
Beamed Energy Propulsion using microwaves or lasers is a promising technology to launch small sized aerospace vehicles. “Lightsail” spacecrafts have captured the imagination of scientists for decades. The earliest recorded description of the idea was published in 1924 by Konstantin Tsiokolvsky and Friedrich Tsander.
Laser-boosted launch system was first suggested by Kantrowitz[2] and Minovich[3] independently. There have been sporadic studies on laser-based propulsion concepts since then. Wang et. al have reported a laser “lightcraft” powered by a 10 kW CO2 laser[4]. A parabolic mirror at the bottom of the craft focuses the laser beam into the engine where the laser heats the air, causing it to break down into plasma. The plasma strongly absorbs the incoming pulse, heating to roughly 18,000 K before exploding from the annular bottom region, generating thrust.
High Power Microwave (HPM) lightcraft development concepts focus on a ground-based microwave transmitter array instead of a laser power to transform the high frequency electromagnetic energy into propulsive power.
The cost benefits of beamed energy propulsion over conventional chemical propulsion concepts cannot be overstated. A small-sized “Lightcraft” sponsored by the USAF Research Laboratory and NASA has already been tested in White Sands, New Mexico desert. The successful tests have helped confirm the promise that useful payloads could be delivered to low-Earth-orbit** using beamed energy propulsion.
Comparison of cost of conventional Vs. Laser propulsion systems[5]
Among the various materials requirements for microwave beamed energy propulsion systems is the need for appropriate window materials. The transfer of radiative energy from one location and its coupling to flowing propellants in a vehicle’s propulsion system at a remote location depends to a large extent on thermally robust, transparent window materials.
Transparent window materials for use in beamed energy propulsion vehicles must satisfy the following conditions[6]-
Diamond windows are best suited for such applications. Transparent ceramics such as aluminum oxynitride (AlON), magnesium aluminate (spinel), and single crystal aluminum oxide (sapphire) also hold promise, not only because of their favorable transparency in the wavelengths of interest, but also due to their robust mechanical properties.
AlON is an isotropic material that can be produced as a transparent polycrystalline compact. The advantage of AlON is that being polycrystalline, it can be shaped in complex geometries using conventional ceramic forming techniques such as pressing and slip casting. Its high cost and the small sizes that can be made limit its application.
Magnesium aluminate spinel (MgAl2O4) is a ceramic with a cubic crystal structure and is transparent in its polycrystalline form. Spinel offers some processing advantages over AlON. It is also capable of being processed at much lower temperatures than AlON, and has been shown to possess superior optical properties within the IR region. Spinel shows promise for many applications, but is currently not available commercially in bulk form from any manufacturer although there is considerable ongoing research efforts to make large sized plates that are 12 x 20 inches by TA&T in Maryland.
Single crystal aluminum oxide (Sapphire - Al2O3) is a transparent ceramic with rhombohedral crystal structure. Its properties are anisotropic and vary with crystallographic orientation. It is currently the most mature transparent ceramic and is available from several manufacturers, but the cost is high due to the high processing temperature involved and machining costs to fabricate parts from single crystal boules. It has a very high material strength, but the transparency is dependent on the surface finish. Fabrication of complex and large sized objects is difficult and often very expensive.
Infrared-transparent polycrystalline alumina shows significant promise for use in the fabrication of transparent windows. With similar chemical composition and physical properties as sapphire, polycrystalline alumina is expected to be ~1/2 as expensive and can be cast into difficult shapes, such as a cylinder. Alumina is also potentially superior to the competing material, aluminum oxynitride (ALON) since it has approximately 3 times greater thermal shock resistance than ALON.
Despite the above promises, “transparent” alumina ceramics obtained so far exhibit lower mechanical parameters than expected and a low in-line transmission of unscattered light (<> 20 µm) .
Sub-micron grained alumina-rich glasses show potential for fabrication of high-strength, transparent windows with good thermal resistance. Although alumina has been conventionally added in small amounts to silicate glasses as a network-former, this oxide cannot be obtained as a bulk glass by itself. Alumina-based glasses can only be prepared by super fast quenching techniques, which limits their dimensions to a few millimeters [7].
A recent development has been reported by a 3M group involving production of high alumina glass by viscous sintering of glass microbeads prepared by rapid quenching of flame sprayed precursors[8]. This opens the route to other related techniques such as plasma spray-quenching.
Study of these window materials is still in the nascent stages, as there is currently not much information available on the effect of high temperature and plasma on these materials. Development of a suitable window material will bring Star-trek type teleportation a century or so closer to reality.
References
1.NASA (1994). Commercial Space Transportation Study.
2. Kantrowitz, A. Propulsion to orbit by ground-based lasers. Astronautics and Aeronautics 10; 74-76 [1972].
3. Minovich, M.A. California Institute of Technology (1972). The laser rocket - A rocket engine design concept for achieving a high exhaust thrust with high ISP.
4. Wang, T.S., Chen, Y.S., et al. (2002). Advanced performance modeling of experimental laser lightcraft. Journal of Propulsion and Power 18(6): p. 1129-1138.
5. http://www.lightcrafttechnologies.com/applications_math.html#compare
6.Harris, D.C; Durable 3-5mm transmitting IR window materials; Infrared Phys Technol. ; 39(4); 185-201 [1998]
7. Weber, J. K. R., Abadie, J. G., Hixson, A. D., Nordine, P. & Jerman, G. A. Glass formation and polyamorphism in rare-earth oxide-aluminum oxide compositions. J. Am. Ceram. Soc 83, 868-872 (2000).
8. Rosenflanz, A; Frey, M; Endres, B; Anderson, T; Richards, E; Schardt, C; Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides; Nature; 430 [2004]
*Isp is the specific impulse: the ratio of the thrust to the flow rate of the weight ejected. It is expressed in seconds.
Isp = F/qg where F is thrust, q is the rate of mass flow, and g is the acceleration of gravity at ground level.
When the thrust and the flow rate remain constant throughout the burning of the propellant, the specific impulse is the time for which the rocket engine provides a thrust equal to the weight of the propellant consumed. Wikipedia gives a detailed description of Isp here.
**The height to which the craft can be propelled depends upon the power of the laser beam. I read here that a 10-kilowatt laser can carry a vehicle the size and weight of an empty soda can into low earth orbit. We would require 10 times the currently available laser power to fly to the edge of space.
Read more...I think Natural Curiosity can teach people about new things........why don't we just use this concept to reduce illiteracy.
Read more...I did not always embrace these perspectives. As a graduate student in Electronics and Communication, I was an atheist, finding no reason to postulate the existence of any truths outside of mathematics, physics and chemistry.
But then I encountered life and death issues at the bedsides of some patients. Challenged by one of those patients, who asked "What do you believe?", I began searching for answers. I had to admit that the science I loved so much was powerless to answer questions such as "What is the meaning of life?" "Why am I here?" "Why does mathematics work, anyway?" "If the universe had a beginning, who created it?" "Why are the physical constants in the universe so finely tuned to allow the possibility of complex life forms?" "Why do humans have a moral sense?" "What happens after we die?"
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