It would "crush" construction companies, just like those horrible building codes, mandatory insulation, double-paned safety glass, adequate sewage systems, safe electrical wiring, earthquake resistant construction and circuit breakers did.
Hmmmmm....
funny they seem to be making record profits in CA.
"Why would I want to buy a home in California if I have to install additional expensive stuff that won't get me my money back yet? I'd rather move elsewhere."
Some people aren't as shortsighted.
The technical facts are:
(*) houses and commercial buildings have a very long valuable lifetime, which is why you can get a 30 year mortgage, and why you need to.
(*) the future path of energy costs may be unknown and may be far more expensive than today. Given the known production rates and declines of North American natural gas production due to actual depletion, this is hardly unlikely. Coal is still, and will be quite polluting and worse for greenhouse emissions.
(*) energy efficient construction and self-generation may be significantly cheaper and more effective and less ugly when designed into a house when originally built. Like, say, indoor plumbing.
(*) there is a major commons economic problem with energy efficiency. You put on one new energy-guzzling house on the grid, say a big cheaply built tract home in a hot area like San Bernadino (where lots of new houses are being put up, as the cool places near the coasts are already completely full) and the customer has to pay a certain electric bill. Fine, it's their problem.
But when lots of people do that, then suddenly there is a large strain on the overall grid capacity and transmission, and the utility has to raise rates significantly for EVERYBODY (not just the new A/C guzzling houses) and everybody suffers from poor service reliability. And of course there is more demand for the limited fuel supply and the price goes up too.
The choices made in building will influence energy consumption for decades to a century.
Are you feeling lucky?
The "Pro-Am"s will be formerly employed Pros.
on
Amateur Revolution?
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· Score: 1
Here's what's really going to happen.
In the technical fields:
The "Pro-Am"'s will be former scientists and engineers who are now scraping by in crappy low-tech jobs after their companies outsourced the Pros to India and China, or after their associated manufacturing plant closed.
In reality, professional scientists who are paid for their work, and have been continuously employed as scientists since graduate school contribute to 99.9% of all actually useful and novel scientific progress.
And this is NOT due to some conspiracy theories or the "Establishment Keeping Innovative Thinkers Down" or any such BS. It's because pros and those who work with pros are the ones who know what they're talking about. I've occasionally reviewed research papers submitted to journals by apparent Pro-Am's (judging from affiliation or lack thereof). Almost always they're crap, often unaware of difficulties or the status of the field. The people who write them are often clearly bright, but that's only a first step.
A few amateur astronomers who are expert comet or asteroid hunters (even at professional quality levels) is insignificant in value next to, say, discovering evidence for life on Titan or figuring out how Dark Energy works.
The era of the Gentleman Scientist is fortunately over. Since, the days of the Wright Brothers (about when things really changed), the era of the corporation and state supported scientists has come, and the total societal value derived from scientific progress has exploded. (in more ways then one, true).
Some journals may be a waste of money, but many aren't.
The whole point of journals is not dissemination---any monkey can put up a web page or archive---but quality improvement.
Where is the added value?
The journal editors do have to make decisions and more importantly they have to know the right people (harder than it sounds) to review, and they have to cajole people into writing the reviews.
On the technical end of things, the published finished papers in journals DO look better, their figures are clearer, the references more complete and checked, and the language is better than preprints. This takes the labor of professional copywriters, who don't work for free.
My papers have been improved by going through the publication process, both in presentation and in content.
Journals don't stay or get prestigious unless they can reliably publish good papers and reliably reject---or fix---crappy papers.
The system is hardly perfect---good papers get rejected and lousy papers do get published----but one has to consider if any alternative would have been any better.
It is extremely naive to imagine that good scientific quality control could be managed by some kind of utopian 'free' on-line review and meta-review system like Slashdot. People's scientific output is a whole lot more important than slashdot posts like this.
Professors do make a name for themselves publishing in prestigious journals. They don't become better known however for being a peer reviewer, as that service is usually anonymous. They do it because they feel they have a moral obligation to do so.
Many societies publish journals as a service and are not-for-profit, e.g. the American Physical Society. And their journals are usually cheaper, and often better, than the pay journals put out by for-profit companies.
I doubt the APS rakes in "loads of cash" without spending it back on fairly essential things.
Steve figured out how to "monetize" his RDF
on
Welcome To Planet Pixar
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· Score: 4, Insightful
RDF, as in his infamous Reality Distortion Field.
turn it into movies.
oh by the way, his other company happens to have invented the most wanted consumer electronic toy since the Playstation.
for being a horrible manager, he is still pretty effective.
Unlike how it was implied in the movie "A Beautiful Mind", John Nash was a successful mathemetician, without illness, for quite a number of years.
He graduated with PhD from Princeton at a very young age (given his talent), and had at least 10 years of a very promising career until his illness hit. It was apparently atypically late for schizophrenics which also may account for his later ability to control it.
Once his illness struck he was useless professionally.
Many years later with his discipline and partial remission he can now function in society but he can't produce research mathematics any more.
Rumors among the jihadi-message boards say that Osama Bin Laden and Ayman al-Zawahiri have started communicating to each other and their followers "in the open", under code names "Darth Sidious" and "Darth Maul".
The National Security Agency said that comment it will not, but you mustn't underestimate the power of the Emperor.
making alot of X-rays very quickly doesn't have to release enough energy to be a bomb on its own.
The question is whether it can be contained, appropriately modulated in its timecourse and shifted to the right frequency so that it can drive the implosion of a fusion capsule. That is how an H-bomb works. The heat from the fission trigger is in fact undesirable for the fusion detonation. The trick there is to contain the x-rays from the fission weapon precisely and direct them to the fusion part in just the right way.
Doing it with metastable hafnium is probably quite unlikely, but you never know.
You would be able to get a fusion weapon without the need of a plutonium trigger. That present requirement sets a minimum yield to be pretty damn big, i.e. no micro-H-bombs.
Supposedly the 'red mercury' could make a thermonuclear explosion.
Consider that it is not the 'red mercury' itself which provides the explosive force, but is the trigger, sans plutonium, which does.
Or perhaps it is a way of making H-bombs without requiring the very detailed engineering of the radiation channels of the present H-bombs, by having the metastable substance modulate and enhance the xrays.
Fortran 95 is a much better language than Fortran 77, and for many things, better than C++ as well.
It is practically a new language with an old name.
If you currently have a F77 code, it is almost certainly far better to start using Fortran 95.
Essentially all Fortran 95 implementations have compile and run-time checks which can make things as safe as Java, and when you take off the checks, things will run very fast. With the Intel Fortran 8.0, probably faster than anything other than hand-tuned assembly. You will probably whip GCC C++.
It is also quite doubtful you will get significantly better performance in C++.
No, I am not an old-fogey (I'm 35 now, programming since age 13). I learned Basic on the Apple II+, then Fortran 77 and C simultaneously when I got my first summer job. Then C++. Then Eiffel and Sather. Then Fortran 95.
Yes, indeed, fully knowing C++ I choose Fortran 95 for technical superiority in the problems I want and need to solve. (Sather was the best ever, but now dead, Eiffel good if you have sophisticated data structures and you don't need multi-dim arrays, and F95 best for any linkage to Fortran and multi-dim arrays, modules but not objects).
The problem is that C++ bugs, though less frequent than bugs in C, are can be deep, subtle and severe. The language has very opaque bits. Include files are antideluvian. Pointers and references, baroque and archaic. Object model brittle. Templates powerful and dangerous. A hideous and error-prone syntax.
This is not the case in Fortran 95. Other than fully algorithmic bugs are shallow.
Green scientists know actual facts
on
A New Ice Age?
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· Score: 1
Mt Pinatubo was significant but only temporary.
The aerosols had a noticable effect, but it does not last long since over a few years they get washed out.
And in fact, the Mt Pinatubo helped verify the actual models of climate used by scientists which in the long run predict global warming and significant climate changes.
In fact a few years ago the temperatures weren't going up as much as the (old) models said they were and the right-wing know-nothings harped on this and said "see you nerds are wrong". Turns out that when the Pinatubo effects were included the models quite precisely matched the observations and now that the effects have washed out the climate has resumed its previous, warming trajectory.
The problem is that the lifetimes for the greenhouse gases are hundreds to thousands of years. The lifetimes of the aerosols from eruptions are much shorter. So in the short run one volcano can make a difference, but in the long run it will not----unless there is some deep internal process in the earth which will greatly alter the rate of volcanism. There is NO scientific evidence for this.
Also, w.r.t. ozone, the depletion of ozone by CFC's in the southern polar regions is now completely verified by in-situ EXPERIMENTAL science and observations.
"ozone depleting" chemicals can mean lots of different things. CFC's and related chemicals are pretty much ONLY the result of human chemistry. They use funky reactions not really found much in nature.
But again most importantly, the CFC's are very LONG LIVED and catalyze the ozone depletion when on the ice crystals in the South Pole weather patterns.
A volcano can emit more chemicals which may be more damaging---in the short run---but because ozone is constantly being created by solar radiation what only matters is the long term chemical balance.
And once again, it really is the exceptional human-produced chemicals that matter.
I agree that there are idiot greens who pay no attention to scientific facts, but it is important to listen to the serious scientists.
It is NOT always the case that real, honest science will always "debunk" the left-wing positions, contrary to what some think.
Nowadays it is much more likely for the right to ignore good science in favor of their own personal wishes.
E.g.: Hey Baystar, go invest in this loser trog company to fight our battles, and when we need to do some investment banking transaction or investment, we'll make sure you can get a sweet part of the deal with a really big commission.
Or, Steve and Bill said they'd put alot of money in your hedge funds if you work on this little problem of ours.
Nothing written of course.
it doesn't take too much imagination to think of plenty of reasons.
Mister Strauss is probably responding, poorly, to some pressure from upper management.
Somebody there heard that free software is great and cheap and thus wanted to cut his budget massively, fire experienced programmers and believe that a few undergraduates can do the same work for cheap.
It is true that you can't get something for nothing, even with free software.
It is also true that it is *possible* (not guaranteed) that you can get more for less money with free software.
Some free software is probably quite high quality---not produced spastically by inexperienced students as Strauss asserts---but other free software is also lower quality too.
I have the feeling the DOE (nuclear weapon simulation etc) simulation program is not going anywhere near as well as it was sold.
Massive commodity clusters boast big numbers but they do not boast great useful throughput of USEFUL RESULTS. (also with massive clusters you have to be able to deal with inevitable hardware failures).
You have a certain fluid problem---there is a certain speed of sound, and a certain physical geometry. What you want to do is to be able to simulate the real thing at ever smaller grid-sizes, that is, with greater numerical approximations to the physical fields.
Ideally, if your problem were embarassingly parallel and clusterizable, then you could put any number of grid points on each CPU and crunch away. You want more grid points? buy more CPUs.
The problem is that in actual physics the length scale of 'interaction' per time step does NOT go down---remember, speed of sound is constant as is physical geometry---imagine for instance the uh, radiative driven implosion of a certain unspecified dense material in spherical or cylinderical geometry into one unspecified not-dense material.
So when you scale-up in the scientifically useful sense---and not the computer nerd sense---then a problem which used to be solvable efficiently on clusters NO LONGER IS SO. There is just too much communication, and this is driven by physical reality.
It is not 'OK' to just say "change your code". The codes are developed with mathematical methods and based on experimental data gleaned over literally decades at great expense.
Programming for these is not easy---but it is quite a bit easier for the large vector old-skool cray type machines than the clusters, where the human has to do almost all the scutwork (e.g. MPI).
The problem is actually more severe with the DOE fluids problem---there are fundamental mathematical issues in the nearly inviscid flow (singular perturbation theory baby) which have not yet been resolved. And they appear at smaller and smaller grid sizes.
This requires rapid development of models and validation at the physically important resolutions and you can't do this with a cluster.
I have no inside information whatsoever but I smell that the sudden DOE and DOD interest in back-to-the-future retrosupercomputing is because of some major failures in the recent cluster efforts.
I actually am a physicist and Thomas Gold is wrong
on
Solar Sailing and Physics
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· Score: 5, Informative
It is obvious that if he is at the Cornell Center for Radiophysics and Space Research, then he is not an actual physicist there. I actually suspect some ulterior motive behind this.
There is no thermodynamic problem with radiation pressure and solar sails, Carnot, Maxwell and Einstein are correct, and Thomas Gold is wrong.
The photons that leave from the Sun are at a Maxwellian distribution at the temperature of the Solar photosphere, many thousands of degrees.
The photons which are re-emitted by the heat of the sail are at the temperature of the sail, which is obviously less than the temperature of the Sun.
There is a temperature gradient, hence work is done.
Gold is also obviously uneducated in physics because of his assertions about how momentum is 'E/c' and how 'E' is a scalar but momentum is a vector, blah blah blah.
The correct way to do an electromagnetic problem like this in purely classical E&M (which is all that is necessary to solve this problem) is to use the stress energy tensor, which is certainly non-zero for propagating electromagnetic waves.
You then use this to find the forces on material bodies, e.g. dielectrics or conductors. You have to think about the stress-energy tensor on both sides of the material body and add up forces. (interesting note, you can also get angular momentum out of this too, appropriately polarized electromagnetic waves can exert a torque).
I learned this in my sophomore year physics class.
Actually, this sounds like a good problem set problem. "Hmmm....now that you ask about it--------yes, it WILL be on the final exam! muahahha."
Given a plane wave source of incoming radiation with flux F_0, with a certain amount of it R1 reflected and the remainder absorbed, what would be the net acceleration in the direction of the radiation of the solar sail with emissivity E once it has reached thermal equilibrium, accounting for all radiation forces. Assume space is at 0 degrees.
What you would do is to put in on the incoming side, the stress energy tensor for the incoming radiation, the outgoing radiation, plus, on both sides, radiation emitted from a black body.
You first get the energy balance right, and then solve for the acceleration.
If you want to be tricky, you would go into the accelerating frame of the sail, and then appropriately red-shift down the incoming frequency of the radiation.
Here is my suspected ulterior motive. This thermodynamic fallacy is exactly the same one that creationists use to deny the obvious explanation for why plants live and complex life evolved.
Namely that the Sun has been providing input energy at 10,000 degrees and the Earth has been re-emitting energy at 300 degrees K and the temperature difference over 4 billion years can do a fair amount of work.
How exactly can Codeweavers ""warrant"" its customers against Microsoft's interference?
Just because Codeweavers says something doesn't mean it's true: "If you buy from me, Big Green Meanie over there can't sue you!" Unless BGM has agreed to this both with Codeweavers and you, how can it have any validity? When did Microsoft give up its rights to sue anybody whom it thinks is violating its licenses and contracts?
To me Codeweavers ""warranty"" seems about as worthwhile as, well, a level-1 godblessyew spell from that homeless guy whom you gave your sandwich.
Saying DNA sequences is a 'fractal' (really self-similar) is nice, but not that profound, yet.
In fact if it were a uniform fractal then it would have VERY LITTLE evolutionary mechanistic importance. Only if the law were sufficiently different that physical mechanisms translating DNA patterns into phenotypes (expression of organisms) could account for observed differences in organisms would something behind the fractal law matter.
Indeed, most of the thinking on the introns is involved in eludicating the mechanisms of the "fractal pattern" but this is all in the mechanisms of replication and crossover. There is little science showing mechanistic (and not just correlations) translations back.
As far as patenting "all methods of observing fractal patterns" I point out this prior art:
R Roman-Roldan, P Bernaola-Galvan, J. L. Olivier, "Sequence compositional complexity of DNA through an entropic segmentation method." Physical Review Letters, V80, p1344 (1998).
Here is its introductory paragraph:
"The analysis of sequence correlation structure, in both the spatial and the frequency domains, resulted in the finding of short range[1] and long-range[2] correlations in nucleotide sequences, thus uncovering a complex fractal structure of DNA."
Both[1] and [2] refer to a large number of references each.
The paper then goes on to discuss an information theory based statistical approach to derive an automated algorithm for hierarchical partition of DNA sequences in to succesively more homogeneous regions. The obsevations is that the breakups are self-similar and thus roughly fractal.
Not only that but the trend towards greater 'complexity' with organism complexity is also observed here.
Note that traditionally fractals are defined on a continuous geometrical space, and since there is a minimum breakpoint size (one base pair) in sequence analysis this is not a true fractal---there will only be self-similarity in some "scaling range".
Note I am a physicist in nonlinear dynamics and happen to know a little bit about information theory. I am not a biology or genetics expert.
People are arguing over the wrong thing. People are debating about what license an academic scientist chooses to release a new project under. That is a legitimate point and I see things going both ways---personally I will release my data analysis code under a more BSDish Academic Free License license.
But this is NOT at all the real point of the law. The reality is much more insidious----this law is designed to STOP all government funding of even academic researchers from working on any improvements to Linux, and in fact any GPL software whatsoever.
It is Microsoft's attack on Linux or any other already EXISTING GPL project.
For instance, the NSA secure Linux versions.
This means that a federally funded CS professor (and most are) could not pay any grad student or postdoc to work on improvements to GCC or the Linux kernel, or any number of similar projects.
In reality it means that they could work only on the BSD's which ironically have far less commercial penetration and significance than Linux.
Which is exactly the REAL intent: harm the competition to Windows.
for contracts where they supply a server and then N cheap boxes, i.e. glorified terminals, running something or other.
Basically it's the Sun Network Computer except now it runs linux and it has email and word processor, and so the people with them don't feel like they were given the gimpiest computers.
It is only because (to be blunt) nuclear physics is not a major subject that you found the Physical Review to be a monopoly journal.
In what I publish in, nonlinear dynamics, I can try for Phys Rev Letters for short articles, Phys Rev E, Chaos, Physics Letters A, Physica D, International Journal of Bifurcation and Chaos; if I were more mathematical there are numerous math journals, and then for engineering applications there is IEEE transactions on circuits and systems, plus the optical science journals for optical applications...
Among all of them, the Physical Review is the best and I choose willingly to submit my paper there. I am amazed at the general quality and efficiency of the editorial process given what meager financial support they have and the large amount of work they have to do.
The non-profit APS gives better results than the for-profit journals.
The idea that somehow an "electronic journal" will suddenly save costs and be cheaper than a regular one is really silly dot-com-thinking. In practice, thanks to the APS's good web access, the Physical Review *is* an electronic journal!
Most people submit electronically and most people download PDF articles that they want to read.
The competency in the journal is in the brains of the editors who know good reviewers and understand science enough to make sound judgements and adjudications, as well as the linguistic and technical skill of the copyeditors who can make the text read well and look good.
A web journal doesn't make any of that cheaper.
I am a native English speaker and thought I carefully proofread my manuscripts but the APS editors always make them look better and read better; I am surprised and impressed by what they can do.
This is highly skilled labor and it doesn't (individually) cost that much to the submitter---the commercial journals are much more expensive to the libraries. In the ratio of value to cost, the Physical Review is the best deal in physics academic publishing.
Publishing has little to do with putting ink on paper and everything to do with words on brains.
The central issue is that in most of the inexpensive single mode fibers, there are random rotations of the polarization state as you transmit light down the fiber.
Moreover those random shifts are time-dependent on account of the physical fluctuations in environment of the fiber optic channel.
That makes traditional polarization modulation difficult to do since the receiver has to dynamically track the unknown polarization matrix correpsonding to the transformation, and that is not easy or inexpensive.
This new method obviates the issue by doing polarization modulation in a distinctly new way, wherein the modulation is in the feedback arm of a chaotic erbium doped fiber ring laser. Changes in the modulation (i.e. message being transmitted) is thus fed back into the dynamics of the transmitter somewhat akin to the state of a cypher (though these schemes are not designed or analyzed to resist cryptanalytic attacks)
There are a few things combined as one then: the production of light in high power (EDRFL), chaotic signal masking by transmitting a high dimensional chaotic state, modulation based on dynamical polarization differences. Also, detection methods for polarization usually require "coherent detection" i.e. interferometry with a coherent source (local laser)---those detectors are much more expensive and difficult than amplitude detectors that measure the short term intensity. Greg has previously shown a technique to use the ampltitude only detectors to nevertheless extract the instantaneous (and not time averaged) polarization state on the Poincare sphere so I expect such techniques to be used in this paper as well.
Just polarization differences via time-delay doesn't work either if you don't have a chaotic underlying carrier as too many things cancel.
I previously collaborated with the two of them on chaotic communication in fiber ring lasers; we derived simulations of the equations of motion and amplitude modulation in the chaotic state. They published experimental results on amplitude modulation in a similar setup before.
1) Yes, chaotic systems do have an entropy rate, production of information in bits per second.
This is the Kolmogorov-Sinai entropy, and when you partition your state space into a discrete form correctly this K-S entropy will equal the Shannon informational entropy rate.
The ideas of entropy can be applied to deterministic dynamical systems when discretized which induces effective 'probabilistic' laws even without assuming any "fundamental" probablism in the laws of motion (which I don't believe anyway).
2) The overall topic seems really silly and is reversing cause and effect.
All reduction in entropy is hardly intelligence.
A complete reduction of configurational entropy is going to a fixed point: e.g. dead.
3) the quoted professor's hysterical denial of any relation between Shannon's "informational entropy" and physical entropy is exaggerated.
It is true that physical entropy does refer to entropy in the specific physically realistic space of the probabilities of particles' degrees of freedom, at least classically, their positions and momenta.
If you apply the theory informational entropy to that particular space, and add in the laws of motion (namely chaos that brings you to physical equilibrium) you get regular physical entropy and thermodynamics.
Information theory is a mathematical theory (and it is great), which can be applied in some circumstances to real physics.
What, did you think that the geophysicists just happened to have forgotten all about that? Quick send this devastating rebuttal to the editor of Geophysical Review Letters.
No. Homie don't think so.
Artificial heating locally will quickly re-equilibrate with the natural observed heat profile.
They can also do things known as "experiments" to check the accuracy of the experimental method.
And see that gee the profile over 614 holes is consistent with a actual experimental phenomenon rather than the drilling procedure and local rock type.
What are the "scientific" ways to measure global warming that are "pseudo scientific pawns".
Re:Asymptotic rate is not good enough.
on
Optical Cryptography
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· Score: 2, Informative
OK here's the deal.
Roughly, Rissanen proved how well any estimator for probabilities that has a total of "k" free parameters that you can use as a coding thing (Kraft inequality and all that).... the extra coding redundancy, i.e. number of bits about N*H where H is the entroypy rate is k/2 log N.
So if you have a source with k free parameters and your receiver is in the same model class and can adapt those 'k' parameters, you will get a redundancy of k/2 log N.
That assumes you know the class.
If you don't know anything about the class it's also been proven that there is no single unviversal appraoch to the limit, i.e. the thing you're asking for in the first part is impossible to get.
For certain classes of input like Markov models, yes the CTW and other methods achieve the Rissanen limit and Lempel-Ziv does not, it has a clearly slower rate of convergence.
You might wonder whether or not LZ does achieve that limit on some other class of sources and CTW does not, but the class of sources that is LZ's is defined very implicitly and it's not very obvious.
There's been nothing found theoretically and in imost practical tests the modeling algorithms (CTW and prediction by partial matching---PPM) seem to be better on compression performance both finite length and asymptotically.
Interestingly the BWT and the subsequent coding of the transformed signal (BWT is only half of the bzip2 algorithm!) turns out to be sort of like a rough approximation to a context-tree kind of method (PPM or CTW) but with some extra glitches.
Yes, some variant of Lempel Ziv compression is "universal".
It doesn't mean that it is superior for finite length data sets, and it may be that BWT and subsequent coding is also universal.
And yes, there are other compression schemes that are essentially better. Lempel-ziv has a certain approach to the entropy rate for certain reasonable classes of sources, markov models.
That rate is not as good as it could be---there is a theoretical limit (Rissanen) that says how good any estimator could get.
There *ARE* compression algorithms that do achieve that limit, and LZ does not, and they are proven to be universal too. (Context Tree Weighting).
They are not used in commonly available hacker-tool programs because they run slower than gzip or bzip2 right now. But the professionals know about them.
Re:No chaotic communication is *not* a one time pa
on
Optical Cryptography
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· Score: 3, Informative
That's close enough for slashdot!
For communication it is one-way synchronization with unidirectional coupling, not the mutual coupling which is more well known in math and physics.
The important point is that the chaos and the 'keys' and the message can all be combined nonlinearly.
Eavesdropper C would need the same chaotic system with the same settings up to some tolerance. Notice that robustness to attack is thus inversely proportional to tolerance to mismatch.
The issue of security is not directly addressed by chaotic communication.
Chaos may be an opportunity to do things other than classical encipherment. It may be like CDMA spreading a signal over a wider frequency band. It may allow you to use cheaper devices or those running past their "normal" tolerance bounds if the requirement for linearity is no longer a factor. It may mean lots of different things; the general point is a greatly increased flexibility and the potential to try widely different kinds of transmission methods. Linear signal transmission is kind of boring, there's AM, FM and minor variations upon those.
However, it may be that some digital ciphers have properties similar to chaotic systems and people are starting to investigate this connection at a different level. that is more mathematics now than communications engineering.
No chaotic communication is *not* a one time pad.
on
Optical Cryptography
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· Score: 4, Informative
This form of chaotic synchronizing communication works by a dynamical systems property. It seems like magic but it is not really.
It relies on the effect of chaotic synchronization. That sort of amazing fact that even though you can have a dynamical system that is continuously unstable in 'some degrees of freedom' making up the chaotic system the combination system of transmitter and receiver can still be stable in the 'transverse' direciton to the synchronization manifold.
All communication systems work by synchronization whether implicitly or explicitly. Here you will explicitly have chaotic oscillators as both transmitters and receivers. Yes, radio is like this too, you have a linear oscillator in the transmitting tower and an oscillator in your RF circuit in your receiver and their electric fields will synchronize the receiver's oscillator to the transmitter.
The trick is how to add in modulation and demodulation that does not destabilize the system and still permit reconstruction of the transmitted information.
All chaotic systems essentially have some sort of nonlinear feedback. The trick that seems to work very frequently with optical dynamics is to mix in some of the transmitted signal coming over the channel with the self-regenerated system at the receiver. In previous work with fiber optic ring laser it really was literally mixing optical signals, in the thing I did it was mixing in electro-optic electrical feedback signals; more like mixing intensities.
It turns out that a fairly generic form of dynamics often seems to work.
I worked on this project from a theoretical modeling level with Jia-Ming Liu's group at UCLA. (We're at UCSD not UCLA).
I'm not sure what this new work is about but in the version that I did there was no significant role for the dynamics or properties of the fiber optics in the creation of the chaos or the demodulation.
It will a very significant amount of engineering to make this fully practical and find all the good properties but that's true for every advance.
Slashdot Mirror
It would "crush" construction companies, just like those horrible building codes, mandatory insulation, double-paned safety glass, adequate sewage systems, safe electrical wiring, earthquake resistant construction and circuit breakers did.
Hmmmmm....
funny they seem to be making record profits in CA.
"Why would I want to buy a home in California if I have to install additional expensive stuff that won't get me my money back yet? I'd rather move elsewhere."
Some people aren't as shortsighted.
The technical facts are:
(*) houses and commercial buildings have a very long valuable lifetime, which is why you can get a 30 year mortgage, and why you need to.
(*) the future path of energy costs may be unknown and may be far more expensive than today. Given the known production rates and declines of North American natural gas production due to actual depletion, this is hardly unlikely. Coal is still, and will be quite polluting and worse for greenhouse emissions.
(*) energy efficient construction and self-generation may be significantly cheaper and more effective and less ugly when designed into a house when originally built. Like, say, indoor plumbing.
(*) there is a major commons economic problem with energy efficiency. You put on one new energy-guzzling house on the grid, say a big cheaply built tract home in a hot area like San Bernadino (where lots of new houses are being put up, as the cool places near the coasts are already completely full) and the customer has to pay a certain electric bill. Fine, it's their problem.
But when lots of people do that, then suddenly there is a large strain on the overall grid capacity and transmission, and the utility has to raise rates significantly for EVERYBODY (not just the new A/C guzzling houses) and everybody suffers from poor service reliability. And of course there is more demand for the limited fuel supply and the price goes up too.
The choices made in building will influence energy consumption for decades to a century.
Are you feeling lucky?
Here's what's really going to happen.
In the technical fields:
The "Pro-Am"'s will be former scientists and engineers who are now scraping by in crappy low-tech jobs after their companies outsourced the Pros to India and China, or after their associated manufacturing plant closed.
In reality, professional scientists who are paid for their work, and have been continuously employed as scientists since graduate school contribute to 99.9% of all actually useful and novel scientific progress.
And this is NOT due to some conspiracy theories or the "Establishment Keeping Innovative Thinkers Down" or any such BS. It's because pros and those who work with pros are the ones who know what they're talking about. I've occasionally reviewed research papers submitted to journals by apparent Pro-Am's (judging from affiliation or lack thereof). Almost always they're crap, often unaware of difficulties or the status of the field. The people who write them are often clearly bright, but that's only a first step.
A few amateur astronomers who are expert comet or asteroid hunters (even at professional quality levels) is insignificant in value next to, say, discovering evidence for life on Titan or figuring out how Dark Energy works.
The era of the Gentleman Scientist is fortunately over. Since, the days of the Wright Brothers (about when things really changed), the era of the corporation and state supported scientists has come, and the total societal value derived from scientific progress has exploded. (in more ways then one, true).
Some journals may be a waste of money, but many aren't.
The whole point of journals is not dissemination---any monkey can put up a web page or archive---but quality improvement.
Where is the added value?
The journal editors do have to make decisions and more importantly they have to know the right people (harder than it sounds) to review, and they have to cajole people into writing the reviews.
On the technical end of things, the published finished papers in journals DO look better, their figures are clearer, the references more complete and checked, and the language is better than preprints. This takes the labor of professional copywriters, who don't work for free.
My papers have been improved by going through the publication process, both in presentation and in content.
Journals don't stay or get prestigious unless they can reliably publish good papers and reliably reject---or fix---crappy papers.
The system is hardly perfect---good papers get rejected and lousy papers do get published----but one has to consider if any alternative would have been any better.
It is extremely naive to imagine that good scientific quality control could be managed by some kind of utopian 'free' on-line review and meta-review system like Slashdot. People's scientific output is a whole lot more important than slashdot posts like this.
Professors do make a name for themselves publishing in prestigious journals. They don't become better known however for being a peer reviewer, as that service is usually anonymous. They do it because they feel they have a moral obligation to do so.
Many societies publish journals as a service and are not-for-profit, e.g. the American Physical Society. And their journals are usually cheaper, and often better, than the pay journals put out by for-profit companies.
I doubt the APS rakes in "loads of cash" without spending it back on fairly essential things.
RDF, as in his infamous Reality Distortion Field.
turn it into movies.
oh by the way, his other company happens to have invented the most wanted consumer electronic toy since the Playstation.
for being a horrible manager, he is still pretty effective.
Unlike how it was implied in the movie "A Beautiful Mind", John Nash was a successful mathemetician, without illness, for quite a number of years.
He graduated with PhD from Princeton at a very young age (given his talent), and had at least 10 years of a very promising career until his illness hit. It was apparently atypically late for schizophrenics which also may account for his later ability to control it.
Once his illness struck he was useless professionally.
Many years later with his discipline and partial remission he can now function in society but he can't produce research mathematics any more.
Rumors among the jihadi-message boards say that Osama Bin Laden and Ayman al-Zawahiri have started communicating to each other and their followers "in the open", under code names "Darth Sidious" and "Darth Maul".
The National Security Agency said that comment it will not, but you mustn't underestimate the power of the Emperor.
The REAL issue of concern isn't being discussed.
making alot of X-rays very quickly doesn't have to release enough energy to be a bomb on its own.
The question is whether it can be contained, appropriately modulated in its timecourse and shifted to the right frequency so that it can drive the implosion of a fusion capsule. That is how an H-bomb works. The heat from the fission trigger is in fact undesirable for the fusion detonation. The trick there is to contain the x-rays from the fission weapon precisely and direct them to the fusion part in just the right way.
Doing it with metastable hafnium is probably quite unlikely, but you never know.
You would be able to get a fusion weapon without the need of a plutonium trigger. That present requirement sets a minimum yield to be pretty damn big, i.e. no micro-H-bombs.
Supposedly the 'red mercury' could make a thermonuclear explosion.
Consider that it is not the 'red mercury' itself which provides the explosive force, but is the trigger, sans plutonium, which does.
Or perhaps it is a way of making H-bombs without requiring the very detailed engineering of the radiation channels of the present H-bombs, by having the metastable substance modulate and enhance the xrays.
Do NOT convert to C++ under any circumstances!
Fortran 77 sucks.
But C++ sucks, in different ways.
Fortran 95 is a much better language than Fortran 77, and for many things, better than C++ as well.
It is practically a new language with an old name.
If you currently have a F77 code, it is almost certainly far better to start using Fortran 95.
Essentially all Fortran 95 implementations have compile and run-time checks which can make things as safe as Java, and when you take off the checks, things will run very fast. With the Intel Fortran 8.0, probably faster than anything other than hand-tuned assembly. You will probably whip GCC C++.
It is also quite doubtful you will get significantly better performance in C++.
No, I am not an old-fogey (I'm 35 now, programming since age 13). I learned Basic on the Apple II+, then Fortran 77 and C simultaneously when I got my first summer job. Then C++. Then Eiffel and Sather. Then Fortran 95.
Yes, indeed, fully knowing C++ I choose Fortran 95 for technical superiority in the problems I want and need to solve. (Sather was the best ever, but now dead, Eiffel good if you have sophisticated data structures and you don't need multi-dim arrays, and F95 best for any linkage to Fortran and multi-dim arrays, modules but not objects).
The problem is that C++ bugs, though less frequent than bugs in C, are can be deep, subtle and severe. The language has very opaque bits. Include files are antideluvian. Pointers and references, baroque and archaic. Object model brittle. Templates powerful and dangerous. A hideous and error-prone syntax.
This is not the case in Fortran 95. Other than fully algorithmic bugs are shallow.
"computer science" truly misunderestimates Fortran 95.
Mt Pinatubo was significant but only temporary.
The aerosols had a noticable effect, but it does not last long since over a few years they get washed out.
And in fact, the Mt Pinatubo helped verify the actual models of climate used by scientists which in the long run predict global warming and significant climate changes.
In fact a few years ago the temperatures weren't going up as much as the (old) models said they were and the right-wing know-nothings harped on this and said "see you nerds are wrong". Turns out that when the Pinatubo effects were included the models quite precisely matched the observations and now that the effects have washed out the climate has resumed its previous, warming trajectory.
The problem is that the lifetimes for the greenhouse gases are hundreds to thousands of years. The lifetimes of the aerosols from eruptions are much shorter. So in the short run one volcano can make a difference, but in the long run it will not----unless there is some deep internal process in the earth which will greatly alter the rate of volcanism. There is NO scientific evidence for this.
Also, w.r.t. ozone, the depletion of ozone by CFC's in the southern polar regions is now completely verified by in-situ EXPERIMENTAL science and observations.
"ozone depleting" chemicals can mean lots of different things. CFC's and related chemicals are pretty much ONLY the result of human chemistry. They use funky reactions not really found much in nature.
But again most importantly, the CFC's are very LONG LIVED and catalyze the ozone depletion when on the ice crystals in the South Pole weather patterns.
A volcano can emit more chemicals which may be more damaging---in the short run---but because ozone is constantly being created by solar radiation what only matters is the long term chemical balance.
And once again, it really is the exceptional human-produced chemicals that matter.
I agree that there are idiot greens who pay no attention to scientific facts, but it is important to listen to the serious scientists.
It is NOT always the case that real, honest science will always "debunk" the left-wing positions, contrary to what some think.
Nowadays it is much more likely for the right to ignore good science in favor of their own personal wishes.
E.g.: Hey Baystar, go invest in this loser trog company to fight our battles, and when we need to do some investment banking transaction or investment, we'll make sure you can get a sweet part of the deal with a really big commission.
Or, Steve and Bill said they'd put alot of money in your hedge funds if you work on this little problem of ours.
Nothing written of course.
it doesn't take too much imagination to think of plenty of reasons.
Mister Strauss is probably responding, poorly, to some pressure from upper management.
Somebody there heard that free software is great and cheap and thus wanted to cut his budget massively, fire experienced programmers and believe that a few undergraduates can do the same work for cheap.
It is true that you can't get something for nothing, even with free software.
It is also true that it is *possible* (not guaranteed) that you can get more for less money with free software.
Some free software is probably quite high quality---not produced spastically by inexperienced students as Strauss asserts---but other free software is also lower quality too.
That is the whole point.
I have the feeling the DOE (nuclear weapon simulation etc) simulation program is not going anywhere near as well as it was sold.
Massive commodity clusters boast big numbers but they do not boast great useful throughput of USEFUL RESULTS. (also with massive clusters
you have to be able to deal with inevitable hardware failures).
You have a certain fluid problem---there is a certain speed of sound, and a certain physical geometry. What you want to do is to be able to simulate the real thing at ever smaller grid-sizes, that is, with greater numerical approximations to the physical fields.
Ideally, if your problem were embarassingly parallel and clusterizable, then you could put any number of grid points on each CPU and crunch away. You want more grid points? buy more CPUs.
The problem is that in actual physics the length scale of 'interaction' per time step does NOT go down---remember, speed of sound is constant as is physical geometry---imagine for instance the uh, radiative driven implosion of a certain unspecified dense material in spherical or cylinderical geometry into one unspecified not-dense material.
So when you scale-up in the scientifically useful sense---and not the computer nerd sense---then a problem which used to be solvable efficiently on clusters NO LONGER IS SO. There is just too much communication, and this is driven by physical reality.
It is not 'OK' to just say "change your code". The codes are developed with mathematical methods and based on experimental data gleaned over literally decades at great expense.
Programming for these is not easy---but it is quite a bit easier for the large vector old-skool cray type machines than the clusters, where the human has to do almost all the scutwork (e.g. MPI).
The problem is actually more severe with the DOE fluids problem---there are fundamental mathematical issues in the nearly inviscid flow (singular perturbation theory baby) which have not yet been resolved. And they appear at smaller and smaller grid sizes.
This requires rapid development of models and validation at the physically important resolutions and you can't do this with a cluster.
I have no inside information whatsoever but I smell that the sudden DOE and DOD interest in back-to-the-future retrosupercomputing is because of some major failures in the recent cluster efforts.
It is obvious that if he is at the Cornell Center for Radiophysics and Space Research, then he is not an actual physicist there. I actually suspect some ulterior motive behind this.
There is no thermodynamic problem with radiation pressure and solar sails, Carnot, Maxwell and Einstein are correct, and Thomas Gold is wrong.
The photons that leave from the Sun are at a Maxwellian distribution at the temperature of the Solar photosphere, many thousands of degrees.
The photons which are re-emitted by the heat of the sail are at the temperature of the sail, which is obviously less than the temperature of the Sun.
There is a temperature gradient, hence work is done.
Gold is also obviously uneducated in physics because of his assertions about how momentum is 'E/c' and how 'E' is a scalar but momentum is a vector, blah blah blah.
The correct way to do an electromagnetic problem like this in purely classical E&M (which is all that is necessary to solve this problem) is to use the stress energy tensor, which is certainly non-zero for propagating electromagnetic waves.
You then use this to find the forces on material bodies, e.g. dielectrics or conductors. You have to think about the stress-energy tensor on both sides of the material body and add up forces.
(interesting note, you can also get angular momentum out of this too, appropriately polarized electromagnetic waves can exert a torque).
I learned this in my sophomore year physics class.
Actually, this sounds like a good problem set problem. "Hmmm....now that you ask about it--------yes, it WILL be on the final exam! muahahha."
Given a plane wave source of incoming radiation with flux F_0, with a certain amount of it R1 reflected and the remainder absorbed, what would be the net acceleration in the direction of the radiation of the solar sail with emissivity E once it has reached thermal equilibrium, accounting for all radiation forces. Assume space is at 0 degrees.
What you would do is to put in on the incoming side, the stress energy tensor for the incoming radiation, the outgoing radiation, plus, on both sides, radiation emitted from a black body.
You first get the energy balance right, and then solve for the acceleration.
If you want to be tricky, you would go into the accelerating frame of the sail, and then appropriately red-shift down the incoming frequency of the radiation.
Here is my suspected ulterior motive. This thermodynamic fallacy is exactly the same one that creationists use to deny the obvious explanation for why plants live and complex life evolved.
Namely that the Sun has been providing input energy at 10,000 degrees and the Earth has been re-emitting energy at 300 degrees K and the temperature difference over 4 billion years can do a fair amount of work.
How exactly can Codeweavers ""warrant"" its customers against Microsoft's interference?
Just because Codeweavers says something doesn't mean it's true: "If you buy from me, Big Green Meanie over there can't sue you!" Unless BGM has agreed to this both with Codeweavers and you, how can it have any validity? When did Microsoft give up its rights to sue anybody whom it thinks is violating its licenses and contracts?
To me Codeweavers ""warranty"" seems about as worthwhile as, well, a level-1 godblessyew spell from that homeless guy whom you gave your sandwich.
Saying DNA sequences is a 'fractal' (really self-similar) is nice, but not that profound, yet.
In fact if it were a uniform fractal then it would have VERY LITTLE evolutionary mechanistic importance. Only if the law were sufficiently different that physical mechanisms translating DNA patterns into phenotypes (expression of organisms) could account for observed differences in organisms would something behind the fractal law matter.
Indeed, most of the thinking on the introns is involved in eludicating the mechanisms of the "fractal pattern" but this is all in the mechanisms of replication and crossover. There is little science showing mechanistic (and not just correlations) translations back.
As far as patenting "all methods of observing fractal patterns" I point out this prior art:
R Roman-Roldan, P Bernaola-Galvan, J. L. Olivier, "Sequence compositional complexity of DNA through an entropic segmentation method." Physical Review Letters, V80, p1344 (1998).
Here is its introductory paragraph:
"The analysis of sequence correlation structure, in both the spatial and the frequency domains, resulted in the finding of short range[1] and long-range[2] correlations in nucleotide sequences, thus uncovering a complex fractal structure of DNA."
Both[1] and [2] refer to a large number of references each.
The paper then goes on to discuss an information theory based statistical approach to derive an automated algorithm for hierarchical partition of DNA sequences in to succesively more homogeneous regions. The obsevations is that the breakups are self-similar and thus roughly fractal.
Not only that but the trend towards greater 'complexity' with organism complexity is also observed here.
Note that traditionally fractals are defined on a continuous geometrical space, and since there is a minimum breakpoint size (one base pair) in sequence analysis this is not a true fractal---there will only be self-similarity in some "scaling range".
Note I am a physicist in nonlinear dynamics and happen to know a little bit about information theory. I am not a biology or genetics expert.
People are arguing over the wrong thing. People are debating about what license an academic scientist chooses to release a new project under. That is a legitimate point and I see things going both ways---personally I will release my data analysis code under a more BSDish Academic Free License license.
But this is NOT at all the real point of the law.
The reality is much more insidious----this law is designed to STOP all government funding of even academic researchers from working on any improvements to Linux, and in fact any GPL software whatsoever.
It is Microsoft's attack on Linux or any other already EXISTING GPL project.
For instance, the NSA secure Linux versions.
This means that a federally funded CS professor (and most are) could not pay any grad student or postdoc to work on improvements to GCC or the Linux kernel, or any number of similar projects.
In reality it means that they could work only on the BSD's which ironically have far less commercial penetration and significance than Linux.
Which is exactly the REAL intent: harm the competition to Windows.
for contracts where they supply a server and then N cheap boxes, i.e. glorified terminals, running something or other.
Basically it's the Sun Network Computer except now it runs linux and it has email and word processor, and so the people with them don't feel like they were given the gimpiest computers.
It is only because (to be blunt) nuclear physics is not a major subject that you found the Physical Review to be a monopoly journal.
In what I publish in, nonlinear dynamics, I can try for Phys Rev Letters for short articles, Phys Rev E, Chaos, Physics Letters A, Physica D, International Journal of Bifurcation and Chaos; if I were more mathematical there are numerous math journals, and then for engineering applications there is IEEE transactions on circuits and systems, plus the optical science journals for optical applications...
Among all of them, the Physical Review is the best and I choose willingly to submit my paper there. I am amazed at the general quality and efficiency of the editorial process given what meager financial support they have and the large amount of work they have to do.
The non-profit APS gives better results than the for-profit journals.
The idea that somehow an "electronic journal" will suddenly save costs and be cheaper than a regular one is really silly dot-com-thinking. In practice, thanks to the APS's good web access, the Physical Review *is* an electronic journal!
Most people submit electronically and most people download PDF articles that they want to read.
The competency in the journal is in the brains of the editors who know good reviewers and understand science enough to make sound judgements and adjudications, as well as the linguistic and technical skill of the copyeditors who can make the text read well and look good.
A web journal doesn't make any of that cheaper.
I am a native English speaker and thought I carefully proofread my manuscripts but the APS editors always make them look better and read better; I am surprised and impressed by what they can do.
This is highly skilled labor and it doesn't (individually) cost that much to the submitter---the commercial journals are much more expensive to the libraries. In the ratio of value to cost, the Physical Review is the best deal in physics academic publishing.
Publishing has little to do with putting ink on paper and everything to do with words on brains.
The central issue is that in most of the inexpensive single mode fibers, there are random rotations of the polarization state as you transmit light down the fiber.
Moreover those random shifts are time-dependent on account of the physical fluctuations in environment of the fiber optic channel.
That makes traditional polarization modulation difficult to do since the receiver has to dynamically track the unknown polarization matrix correpsonding to the transformation, and that is not easy or inexpensive.
This new method obviates the issue by doing polarization modulation in a distinctly new way, wherein the modulation is in the feedback arm of a chaotic erbium doped fiber ring laser. Changes in the modulation (i.e. message being transmitted) is thus fed back into the dynamics of the transmitter somewhat akin to the state of a cypher (though these schemes are not designed or analyzed to resist cryptanalytic attacks)
There are a few things combined as one then: the production of light in high power (EDRFL), chaotic signal masking by transmitting a high dimensional chaotic state, modulation based on dynamical polarization differences. Also, detection methods for polarization usually require "coherent detection" i.e. interferometry with a coherent source (local laser)---those detectors are much more expensive and difficult than amplitude detectors that measure the short term intensity. Greg has previously shown a technique to use the ampltitude only detectors to nevertheless extract the instantaneous (and not time averaged) polarization state on the Poincare sphere so I expect such techniques to be used in this paper as well.
Just polarization differences via time-delay doesn't work either if you don't have a chaotic underlying carrier as too many things cancel.
I previously collaborated with the two of them on chaotic communication in fiber ring lasers; we derived simulations of the equations of motion and amplitude modulation in the chaotic state. They published experimental results on amplitude modulation in a similar setup before.
Three points.
1) Yes, chaotic systems do have an entropy rate, production of information in bits per second.
This is the Kolmogorov-Sinai entropy, and when you partition your state space into a discrete form correctly this K-S entropy will equal the Shannon informational entropy rate.
The ideas of entropy can be applied to deterministic dynamical systems when discretized which induces effective 'probabilistic' laws even without assuming any "fundamental" probablism in the laws of motion (which I don't believe anyway).
2) The overall topic seems really silly and is reversing cause and effect.
All reduction in entropy is hardly intelligence.
A complete reduction of configurational entropy is going to a fixed point: e.g. dead.
3) the quoted professor's hysterical denial of any relation between Shannon's "informational entropy" and physical entropy is exaggerated.
It is true that physical entropy does refer to entropy in the specific physically realistic space of the probabilities of particles' degrees of freedom, at least classically, their positions and momenta.
If you apply the theory informational entropy to that particular space, and add in the laws of motion (namely chaos that brings you to physical equilibrium) you get regular physical entropy and thermodynamics.
Information theory is a mathematical theory (and it is great), which can be applied in some circumstances to real physics.
What, did you think that the geophysicists just happened to have forgotten all about that? Quick send this devastating rebuttal to the editor of Geophysical Review Letters.
No. Homie don't think so.
Artificial heating locally will quickly re-equilibrate with the natural observed heat profile.
They can also do things known as "experiments" to check the accuracy of the experimental method.
And see that gee the profile over 614 holes is consistent with a actual experimental phenomenon rather than the drilling procedure and local rock type.
What are the "scientific" ways to measure global warming that are "pseudo scientific pawns".
OK here's the deal.
Roughly, Rissanen proved how well any estimator for probabilities that has a total of "k" free parameters that you can use as a coding thing (Kraft inequality and all that).... the extra coding redundancy, i.e. number of bits about N*H where H is the entroypy rate is k/2 log N.
So if you have a source with k free parameters and your receiver is in the same model class and can adapt those 'k' parameters, you will get a redundancy of k/2 log N.
That assumes you know the class.
If you don't know anything about the class it's also been proven that there is no single unviversal appraoch to the limit, i.e. the thing you're asking for in the first part is impossible to get.
For certain classes of input like Markov models, yes the CTW and other methods achieve the Rissanen limit and Lempel-Ziv does not, it has a clearly slower rate of convergence.
You might wonder whether or not LZ does achieve that limit on some other class of sources and CTW does not, but the class of sources that is LZ's is defined very implicitly and it's not very obvious.
There's been nothing found theoretically and in imost practical tests the modeling algorithms (CTW and prediction by partial matching---PPM) seem to be better on compression performance both finite length and asymptotically.
Interestingly the BWT and the subsequent coding of the transformed signal (BWT is only half of the bzip2 algorithm!) turns out to be sort of like a rough approximation to a context-tree kind of method (PPM or CTW) but with some extra glitches.
The advantage is that it's computationally fast.
Yes, some variant of Lempel Ziv compression is "universal".
It doesn't mean that it is superior for finite length data sets, and it may be that BWT and subsequent coding is also universal.
And yes, there are other compression schemes that are essentially better. Lempel-ziv has a certain approach to the entropy rate for certain reasonable classes of sources, markov models.
That rate is not as good as it could be---there is a theoretical limit (Rissanen) that says how good any estimator could get.
There *ARE* compression algorithms that do achieve that limit, and LZ does not, and they are proven to be universal too. (Context Tree Weighting).
They are not used in commonly available hacker-tool programs because they run slower than gzip or bzip2 right now. But the professionals know about them.
That's close enough for slashdot!
For communication it is one-way synchronization with unidirectional coupling, not the mutual coupling which is more well known in math and physics.
The important point is that the chaos and the 'keys' and the message can all be combined nonlinearly.
Eavesdropper C would need the same chaotic system with the same settings up to some tolerance. Notice that robustness to attack is thus inversely proportional to tolerance to mismatch.
The issue of security is not directly addressed by chaotic communication.
Chaos may be an opportunity to do things other than classical encipherment. It may be like CDMA spreading a signal over a wider frequency band. It may allow you to use cheaper devices or those running past their "normal" tolerance bounds if the requirement for linearity is no longer a factor. It may mean lots of different things; the general point is a greatly increased flexibility and the potential to try widely different kinds of transmission methods. Linear signal transmission is kind of boring, there's AM, FM and minor variations upon those.
However, it may be that some digital ciphers have properties similar to chaotic systems and people are starting to investigate this connection at a different level. that is more mathematics now than communications engineering.
This form of chaotic synchronizing communication works by a dynamical systems property. It seems like magic but it is not really.
It relies on the effect of chaotic synchronization. That sort of amazing fact that even though you can have a dynamical system that is continuously unstable in 'some degrees of freedom' making up the chaotic system the combination system of transmitter and receiver can still be stable in the 'transverse' direciton to the synchronization manifold.
All communication systems work by synchronization whether implicitly or explicitly. Here you will explicitly have chaotic oscillators as both transmitters and receivers. Yes, radio is like this too, you have a linear oscillator in the transmitting tower and an oscillator in your RF circuit in your receiver and their electric fields will synchronize the receiver's oscillator to the transmitter.
The trick is how to add in modulation and demodulation that does not destabilize the system and still permit reconstruction of the transmitted information.
All chaotic systems essentially have some sort of nonlinear feedback. The trick that seems to work very frequently with optical dynamics is to mix in some of the transmitted signal coming over the channel with the self-regenerated system at the receiver. In previous work with fiber optic ring laser it really was literally mixing optical signals, in the thing I did it was mixing in electro-optic electrical feedback signals; more like mixing intensities.
It turns out that a fairly generic form of dynamics often seems to work.
I worked on this project from a theoretical modeling level with Jia-Ming Liu's group at UCLA.
(We're at UCSD not UCLA).
I'm not sure what this new work is about but in the version that I did there was no significant role for the dynamics or properties of the fiber optics in the creation of the chaos or the demodulation.
It will a very significant amount of engineering to make this fully practical and find all the good properties but that's true for every advance.