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/joeyo

Could this be what you're after?

since thermal effects would make the refractive index near the center of the beam lower, not higher.

Yep. My bad. I read about it a very long time ago so I included an "If I recall correctly" disclaimer.

I think there has to be a nonlinear interaction between the beam and the air that induces a photorefractive effect that increases the index of refraction near the center of the beam in order for self-focusing to occur.

Yep. It turns out it's the Kerr effect. I just did a google search on self-focusing and laser. 3,920 hits. There are several different topics and methods covered. This one gives a pretty good explanation of how to get self-focusing in atmosphere.

At extremely high laser intensities relativistic effects come into play. The kerr effect says that higher intensity increases the index of refaction(IOR). Since the center of the beam has a higher intensity the center has a higher IOR and the beam converges.

The second problem is that self-focusing is a positive feedback loop, such that self-focusing causes more self-focusing, which makes the beam more and more intense toward the center. Eventually the beam intensity will exceed the breakdown voltage of air, and the air will ionize. This actually make the air opaque

Mostly correct. It converges until it hits 10^14 watts/cm^2 and ionizes the air. But the ionization doesn't cause it to become opaque, it decreases the IOR and causes the beam to diverge. The beam therefore stabilizes right at the ionization threshhold.

-

This 'material' is an electrical circuit in a transmission line. They were simulated using Agilent's ADS software, which is used for design of "products such as cellular and portable phones, pagers, wireless networks, and radar and satellite communications systems" (from Agilent's page). The electrical fields are closer to microwaves then visible light & can be measured in voltages. No-one is going to beat data-density records using microwaves & to even talk about lenses is a trifle far-fetched. The principles & physics behind this breakthrough are general but in practice these man-made materials are going to have to be manufactured & we're nowhere close to that. This discovery was published in Applied Physics Letters (Vol. 82, No. 12, 24 March 2003, p. 1815 for those of you with institutional subscriptions).

This is somewhat akin to applying rules for radio waves to infrared photons, sure the equations all work but in practice the two electromagnetic fields behave somewhat differently.

Chris

PhD candidate
Dept. of Chemistry
University of Toronto

For Slashdotters at universities or other institutions that have an institutional subscription to Applied Physics Letters, here is the original scientific paper that's mentioned in the articles.

However, there has been an interesting exchange (with comment and reply) in Physical Review Letters refuting such claims. (These are subscription journals but should be available in most academic and research institutions).

Finally, read the Seven Warning Signs of Bogus Science by Bob Park (even though rule 1 does not apply here).

However, there has been an interesting exchange (with comment and reply) in Physical Review Letters refuting such claims. (These are subscription journals but should be available in most academic and research institutions).

Finally, read the Seven Warning Signs of Bogus Science by Bob Park (even though rule 1 does not apply here).

The 'transcendence' is an artifact of the NewsFactor writer who clearly misunderstood what was being said.

Anyone that has had a high school physics class or a few semesters of introductory physics in college remembers snell's law and that infernal little quantity called 'n' that describes the characteristics of the material with respect to light. What they don't tell you in those classes is that you aren't even getting half of the picture.
Initially, you see n defined as c/v, where v is the speed of light in the material. Since v is less than c (always) this number is always greater than 1 except for vacuum. This is where the 'wierd science' part comes is, and the fact that you're only getting a fraction of the picture. In reality, n has both real and imaginary parts - the imaginary part decribes the 'folding' or how much the wave magnitude decays in the medium over distance and time. For example, if you took something that measured the intensity of light outside in the sunlight and compared it to the intensity of light behind a window in a house, the intensity *inside* would be less because the glass absorbs a certain amount of energy of the light as it passes through. As you can see, this 'n' thing is a little more complicated than what you learned initially in high school and college - end result, well, they sorta lied to you. In fact, the above is just scraping the barrel because you're still trying to give physical credence to a mathematical model.
The 'bad science' comes from putting too much faith in what the math really means. Guys, math is just a tool to *model* reality. If you put too much credence in it you start to think that stuff like virtual particles and feynman diagrams are real. They aren't. They're a tool used by physicists to get an answer that agrees with experiment. For more info on negative index of refraction stuff look at what these guys did, and also look here for a little more info.
Not that it isn't cool to hope that things go faster than light and that we're just getting part of the picture...

I wish I could be more enthusiastic about Robert Park's list, but it's never so simple. Much of good science fails some of these tests and much of the bad science passes it.

He puts too much faith in peer review. I realize it's all we've got, but it's failed again and again and again. The other scientists just don't have the time to do a good job and many times they have ulterior motives. That's why the peer review journals have printed so many faked articles recently. (Read here or here for starters. )

I would believe his claim about pitching to the media directly, if he didn't do it himself so often. Was his column peer reviewed? His weekly news summary is entertaining, but his smug sense of superiority really grates on me. How in the hell does he know that cold fusion doesn't exist? You can't prove a negative, but there he goes trashing Fleischman and Pons. I'm not saying that cold fusion does exist, but I think it's more complicated than his sound bite. Let's face it, Park is as much of a media whore as the other scientists and he's just as prejudiced.

His other list items are just as faulty. Most scientists work in some kind of isolation because they don't want others to scoop them. But let me guess, the guys who are friends of Park aren't in isolation because they're hanging out with him.

Plus, new laws of nature are what science is all about. We don't need people dropping rocks all day and then announcing, "Yup, gravity still works." We want people probing the undefined areas of knowledge where marginal results leave us confused. That's the whole point.

The deepest problem is the faith we place in the scientific method. We want those guys in white coats to ladle out pure truth. That's why we spend
so much tax money on them. But it's never so simple especially when the phenomena are new or strange. He says you can always find some scientist to certify anything. So what good are scientists? I know, other scientists are the problem. If everyone would just listen to Park,
everything would be alright.

Park could handle this a bit better if he wasn't so arrogant. A more enlightened stance is to say that the scientific method takes a long time to converge on an answer and even then it may not be right. But it's the best we can do.

The work of Achim Hartschuh, Erik J. Sánchez, X. Sunney Xie, and Lukas Novotny has been published by Physical Review Letters, Volume 90, Number 9, March 7, 2003. Here is a link to the abstract of their paper, "High-Resolution Near-Field Raman Microscopy of Single-Walled Carbon Nanotubes." You also can read the summary I wrote on this subject, "The Smallest Sight: Researchers Zoom In on the Nanoscale."

David Criswell published a good review of the concepts for lunar solar power in the April 2002 issue of the Industrial Physicist. Mining and processing lunar silicon would allow a bootstrap process that could result in huge levels of power being available to Earth directly from the Moon. The recent Science magazine article on our energy future listed space-based solar power and in particular this lunar option as one of the most promising to resolve our energy problems over the next few decades.

The problem is getting any economic return requires a huge up-front investment - and no government or private body has yet stepped up to the potential opportunity. Maybe China will be it...

One that I like can be found here.

Something good: Brought to you be the Bush Administration.

No one dares mention that its a decision by the Bush administration when its something good. Why is that ?

If you knew the posistion of every particle in the universe, as well as all physic laws and plotted this into a computer, would you be able to figure out the future by fast-forwarding?

Not according to Heisenberg.

For three reasons (at least), this "theory" of yours is complete bunk.

First, and most seriously, you say, "Relativity is theory, not law." This indicates a fundamental misunderstanding on your part of the Scientific Method. The fundamental difference between a theory and a law is that a law reflects and may predict observations, while a theory explains observations. This link at the Mad Sci network will give you a bit more background on the distinction.

Second, Heisenberg's Uncertainty Principle deals not with intensity and position of waves, but with the velocity vs. position of particle-waves. More specifically: "The more precisely the position is determined, the less precisely the momentum is known" (American Institute of Physics). Gravity waves are theorized to exist, but to date we have yet to detect one.

Third, you call your hare-brained idea a "theory," which it is not. At the very best, it is a hypothesis; but since you present no observations to support your idea, I hesitate to give it even that distinction. In short, what you have is an opinion--and an unfounded one at that.

A good thought experiment to carry out, which may reflect what the astronomers who performed the experiment attempted to measure, is this: watch a star's position as it nears Jupiter (and watch closely, because when it moves, it won't move much). Jupiter's mass is known; and from that we can predict how far away Jupiter will be when its gravity bends the star's light. If the star's light bends before Jupiter reaches this distance, we can conclude that the effects of Jupiter's gravity reached us before the light from Jupiter reached us, and therefore that gravity is faster than light.

And that makes me think that photons can self-gravitate:
They are affected by gravity
They "bend space" like mass, so produce a gravitational field.

You are entirely correct. A photon has energy and momentum, thus it generates a gravitational field, even though it has no rest mass. It is also subject to a gravitational field, as was found to be the case in 1919.

Hell, gravity should self-gravitate, and there was an experiment to try to determine whether it does, and they appear to have found that it does....

Here's a real mystery which we still can't figure out: Anomalous Acceleration of Pioneer space probes. This one, like the dark energy problem, hints at fundamental problems with our view of the universe.

There are a lot of scientific reasons to go back to the Moon - first a lot of questions about the Moon itself, and the early history of the solar system that can be learned from lunar cratering. Of most interest in this is the South Pole - Aitken basin, which is mostly on the far side; the south polar regions of this very deep basin have craters that may hold water ice and other cometary debris. But the basin material is itself of some geological interest, and a sample-return mission to this area was listed as one of the highest priorities in planetary science in the recent NRC decadal survey.

Second, for science, is the potential of the Moon as a platform for observation of the rest of the universe. A lunar telescope has the same lack-of-atmosphere advantages of Hubble, but could be constructed much larger than is possible for a free-space telescope (with current technology) with use of in-situ materials. This is particularly important for infrared and ultraviolet/x-ray astronomy, for which much of the spectrum is almost completely attenuated in the Earth's atmosphere and space is the only real option. It makes a lot of sense to base the next generation of space telescopes on the Moon, though I have not seen much movement in this direction, other than some early-stage proposals.

Space solar power is considered by many to be the only long-term solution to Earth's energy needs that meets both global energy and environmental requirements over the next 50 years. Making use of lunar materials, possibly even generating the power on the Moon, is the only realistic option for building these things on the scale needed. If this globe could ever manage to get its act together and move beyond carbon-based fuels to invest in the future, the Moon has a major role to play.

Finally, space tourism has been in the news, and private companies are starting to look at orbiting hotels and lunar excursions - for those who can pay of course. With the right price, demand can be expected to be huge :-) Retirement to the Moon's low gravity might become a major draw as well.

So the Moon has a bright future - if we could just pay it a bit of attention with all the other distractions the world has to offer these days!

What the hell are you talking about?

Journal of Applied Physics

That is indeed a refereed scientific journal, sponsored by the American Institute of Physics.

Perhaps you were merely being sarcastic and implying that JAP isn't a top tier journal. If so, remember to use your _SARCASM_ JAP rocks _/SARCASM_ tags or italicize something.

-Rothfuss

First, here is the abstract for the article.

Second, it doesn't work, at least not the way they say it does. You can't store 1024 bits in the nuclear magnetic spins of a 19 atom molecule!

Or more precisely, you can't retrieve that many bits. The spin state of a nucleus can be described by a complex number, but when you do a measurement you only get one bit out. With 19 nuclei you can read out only about 19 bits.

So how do they make it work? They've got a huge number of molecules there. Each one is loaded with the same data value. Using the redundancy in those molecules, the researchers can read out the 1024 bits. But if they had only a single molecule holding the value in its nuclear spins, as the paper implies, there's no way they could read out 1024 bits. So the density is not as high as they make it sound.

there is only so many times in a day you can "go make coffee" or "check your email".

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• The Effects of Moore's Law and Slacking 1 on Large Computations

Hope this helps =)

Nothing new or magical in the theory, but it is a really cool application. Kudos to the researchers.

Here's another links. I didn't feel like registering.
I wonder if this technology could be applied to healthy individuals to allow higher than normal agility maybe for soldiers fighting in unstable enviroments where they may lose their footing.

European scientists have carried out the first experiments on antimatter.
Wrong. They've been experimenting with antimatter for years. I think Carl Anderson's 1930s work was the first. This isn't even the first experiment with antihydrogen, or cold antihydrogen, for that matter.

Researchers in Geneva, Switzerland, have been able to trap and control anti-hydrogen atoms in a chamber at a sufficiently low temperature to begin studying their physics in detail.
Wrong. They haven't trapped it. Nor can they study the physics in detail yet.

Now they say they can store these fragile objects for study as well, allowing them to conduct simple experiments.
Wrong. They can't trap them, much less store them for any length of time.

By measuring the strength of the electric field, they hope to tell how tightly an anti-atom is held together and shed light on the differences between normal matter and antimatter that might explain why the Universe exists in its present form.
Not quite. They are able to tell how tightly these particular positrons are bound to their antiprotons, which reveals what quantum state the antihydrogens are in; this doesn't tell you anything about the properties of antihydrogen.

Cern physicist Jerry Gabrielse...
And, um, it's Gerry Gabrielse.

Much better articles available here, here, and here.

Oh, he's trolling... just take a look at his posting history.

Regarding Szilard's patent application - according to this page it's likely that his first patent on accelerators was rejected due to "prior art". Of course, file the same thing today and I bet you get a patent.

From that page it's not clear if his cyclotron or betatron patents were granted or not.

As for moderation - I didn't expect to get modded up. PG just deserves to get modded into a -1 hole.

Looks like they've managed to duplicate one of the first cyclotrons. Question is, what are they going to do with it?

"[Curie], who handles daily a particle of radium more dangerous than lightning, was afraid when confronted by the necessity of appearing before the public.""--Stéphane Lauzanne, editor-in-chief of Le Matin

Of course, I could be applying my early 21st century knowledge to her early 20th century situation.

Highly intelligent? Yeah, sure!

Dumb? Absolutely!

rkowen writes...

For those playing at home, rkowen didn't write shit. That is, unless rkowen is Bertram Schwarzschild (or an editor) over at Physics Today who wrote the abstract in the friggin' article linked to in the /. summary.

One might think the /. community is full of frauds...

Link

In my mind the best solution to the problem would be adding more journals to the SPIN data base (or some similar base)

Bull. Check out just this ONE site: ojps.aip.org.

Bitch, bitch, bitch, bitch, bitch. To quote someone who dearly needs to be heeded in this case (Dennis Leary), "Shut the fuck up, NEXT!" I've heard enough crap, why don't we just call up Nikon and ask them for one of their explosive imaging cameras? If I remember my Guinness Book of World Records, that unit is a digital camera performing in the MILLIONS of frames per second! 12,000? Feh!

Gee, how about a simple Google search, even? Let's try that, shall we (since the Guinness world record site SUCKS!):

• "Fastest Camera" search
  First 3 links are about the same camera! A half-million dollars, 200 million frames per second.

• "Ultrahigh-speed Imaging" search
  Grab the .PDF in that first hit -- it's from "The Industrial Physicist", and has some nice info on a "gated still-video camera." A quote:
  • "Multisensor, ultrahigh-speed electronic imaging systems (such as that shown in Figure 1) are capable of recording sequences of discrete images at frame rates of up to 100 million pictures per second. They incorporate compact, intensified charge coupled device (CCD) modules that exhibit virtually no geometric distortion or intensity variation and provide the user with digital images that can be analyzed using a personal computer."

  Oh, one other thing: The article is from December 1997 when Pentium IIs were hot stuff, and you counted yourself lucky to have 64 MB of RAM and a 9.1 GB F/W SCSI-2 hard drive!

Read the paper. This is a way of fabricating gold nanoparticles, not extracting gold. They grow small amounts of alfalfa in a controlled environment with extra gold in the soil. The gold nanoparticles are useful for some biosensor applications, because they will bond to DNA and can easily be detected.

Ahem. Demonstrating the reason for the preview button, the journal is here (subscription required to read articles)

(yes I know it's not the same Jon Katz, at least I think I know it's not the same Jon Katz - the writing style sure looks different). ;)

CDT (Cambridge Display Technology) was touting LEPs as the next LED that is capable of high refresh rates and the ability to see from angles, all because the technology doesn't use a backlight but instead the plastic itself emits light.

Among some of the other advantages I remember highlighted was the ability to create strange pixel configurations, low power usage, and a relatively inexpensive manufacturing process.

We'll have to see what promises it will live up to...

Semiconducting Polymers on Display

I will state the obvious for those who have not actually done scientific research.

The problem now is if we do not see immediate gains then the project should be scrapped. But, this is not the way science works. It actually takes engineering efforts to do real science. Delays and over runs when doing something no one has done before are unforuantely they way things work. The buisnesslike attitude of the government does not like to hear that. They want to know exactly how much something will cost and when it will be done. So, the scientist give their best estimates and then append them when they have more information.

Yes there are wasteful projects and unforunate tragedies but MOST of the time they are wastful because the end result is not useful and there was little technology spinoff. The better-cheaper-faster approach presented by Dan Goldin in the early ninties was wholehartedly praised by most everyone. Using comercial satelite technology, limiting expensive protective measures and minimizing staff were good ideas untill we lost three missions to mars and about the only thing we learned was we cutting corners on space exploration is risky.

Science is expensive. But so is everything else. Osprey V-22, 12B$ so far three years late and still not working but they expec to sink 38B$ for the whole program. NIF, 3.9B$ it violates treaties, two years late and we dont know if it works yet. I could go on.

It is not fair to cut the operating budget of the program and limit the growth of the project and then say there is no science going on. Bush and O'Keefe want a failure so Nasa's measily little budget (~=15B$) can be diverted to tax cuts or absorbed by Defence's everincreasing budget (~=360B$).

Why can't they just add that into the article? It seems to me that these articles are just out there to introduce the new buzzwords that the author just learned.

BTW, wasn't it found from the "closing of the solar neutrino problem" that neutrinos do undergo flavor fluctuations? Didn't that make this experiment pointless?

Mach, P. et al. Tunable microfluidic optical fiber. Applied Physics Letters, 80, 4294 - 4296, (2002). You might need a subscription to read it though, not sure.

Basically the application is a wavelength selective filter for WDM. They are likely looking at arrays of these for WDM switching, as a fiber based alternative to MEMS.

There are a lot of GR corrections that one must make to GPS to get decent accuracy out of it. In fact, there is a bit of a scandal because none of the GPS receiver makers have made public their correction formulae (standard "if we publish then we'll just be helping our competitors" philosophy).

There was a good article in the May edition of Physics Today about relativistic corrections to GPS, unfortunately the web version isn't free. If you're near a university, they should have copies of PT in their physics library.

Have a look
here if you want to read more regarding GPS birds and relativity

An article (membership requires) in May Physics Today details the extensive corrections GPS must make for both special relativity (velocity corrections) and general relativity (gravity corrections). This has tested Einstein every day of the past 20 years, and he has held up.

A paper appeared in Applied Physics Letters, Volume 80, Issue 20, pp. 3817-3819

- Rob

Wow, he's got to be the only goy in the Jewish American Hall of Fame! And to think he was offered the presidency of Israel! And all those synagogues named after him! And, above all else, the fact that both of his parents were Jewish!

Truly a remarkable man, to have remained non-Jewish through of all that!

For those of you freaking out, here's a link Strangelets are strange but not dangerous

Somehow nobody has yet linked to Criswell's original article, which was published in the current issue of the Industrial Physicist, put out by the American Institute of Physics, a highly respected research physics organization in the US.

In other words, Criswell is no crackpot; this is a realistic plan. Read the article. I don't entirely agree with him - I think lunar materials could more effectively be used to construct orbiting solar power satellites - launch from the lunar surface can be very cheap using electromagnetic railgun technology, and in orbit you can get sunlight 100% of the time, not 50% (with solar incidence angle effects to worry about too). But Criswell's scheme is one of the most promising options, and should be considered seriously.

How soon could this be done? Essentially all the technology is in place - the scheme could benefit from some further developments of robotics, but a first launch date of 2010 is not unrealistic, and we could have power from the Moon before we would see anything from ANWR :-)

Somehow nobody has yet linked to Criswell's original article, which was published in the current issue of the Industrial Physicist, put out by the American Institute of Physics, a highly respected research physics organization in the US.

In other words, Criswell is no crackpot; this is a realistic plan. Read the article. I don't entirely agree with him - I think lunar materials could more effectively be used to construct orbiting solar power satellites - launch from the lunar surface can be very cheap using electromagnetic railgun technology, and in orbit you can get sunlight 100% of the time, not 50% (with solar incidence angle effects to worry about too). But Criswell's scheme is one of the most promising options, and should be considered seriously.

How soon could this be done? Essentially all the technology is in place - the scheme could benefit from some further developments of robotics, but a first launch date of 2010 is not unrealistic, and we could have power from the Moon before we would see anything from ANWR :-)