Slashdot Mirror

I reckon aliens would have a hard time picking up TV stations from mars, never mind light years away.

Assume that the aliens have a radio telescope that is comparable to the one at Arecibo. I don't have numbers on its sensitivity after recent upgrades, but a ball-park figure I have heard is that it can pick up a cell phone transmission within a sizable part of the solar system near earth.

A rough calculation reveals that perhaps a 10^14 W source at the centre of our galaxy (2.2 x 10^4 light-years away) could be detected by Arecibo. Compare this to terrestrial television (~10^6 W) and radio (~10^5) stations, and you'll find that it could be on the edge of possiblility for Arecibo to pick up TV transmissions from a planet 41 light-years away.

It it worth noting that the progress made in fusion research has been HUGE throughout the past 3-4 decades and while the next step is more difficult than the last we aew still making steady progress. JT-60 HAS attained a confinement quality in the deuterium-deuterium shots it has taken which are VERY good, so good that if they were done with deuterium-tritium mix they would firmly place JT-60 in the breakeven parameter space very near the ignition regime (they have not "gone DT" due to pain in the ass handling issues with the radioactive tritium). There is also always hope for a shocking surprise breakthrough too (but don't hold your breath). For example, 10 or so years ago, it was though there was no way you could get around having to build immensely expensive multi-hundred beam multi-MEGAjoule laser systems in order to make inertial confinement fusion work. Then along comes a cute little trick called Chirped pulse amplification and suddenly you can start talking about petawatt lasers being used to reduce the overall cost of the machine by 10 fold (fast ignition fusion schemes! That's why science is so great, there is always hope something better is just around the corner waiting to be discovered.

Basically, you're looking for signs of psychological stress.
No, this is wrong. fMRI looks at blood oxygen levels (BOLD) in the brain - which indicate what part of the brain is being used. Lying requires more brain horsepower than telling the truth and the parts of the brain used for lying are known. They are different than just recall. This is indeed looking into the brain working and not a side effect like sweating. The recall parts of the brain are known too and thus can be used to determine if you've know a person. Flash a photograph of the person and if the recognition part fires, then it shows you've seen that person. You don't even have to punch a button...
Having said that, near IR is a much easier technique to look into the brain and only requires strapping some IR emitters/detectors on the subjects forehead. A link is here. Cost is way less than the millions for an fMRI that requires a supercon magnet and Faraday cage. And the subject need not be as cooperative.

In this case, they had the source, which tells me that the scientists that got caught weren't exactly the sharpest spoons in the drawer.

Here's a prior slashdot posting about mathematical techniques to identify photo manipulation. And another article detailing some techniques.

Another first silicon laser? So who was really first?

----
http://oemagazine.com/newscast/2004/102604_newscas t01.html

Los Angeles, CA | 26 October 2004 -- Researchers at UCLA have demonstrated the first silicon laser, which could lead to more effective biochemical detection, secure communications, and defense against heat-seeking missiles.

----
http://www.intel.com/technology/silicon/sp/

First Continuous Silicon Laser

In a paper published February 17, 2005 by the prestigious scientific journal Nature, Intel researchers disclosed the development of the first continuous wave all-silicon laser using a physical property called the Raman Effect. They built the experimental device using Intel's existing standard CMOS high-volume manufacturing processes. This is the third silicon photonics paper Intel has published in Nature since 2004, beginning with the modulator breakthrough (see the Learn More section).

----
http://www.photonics.com/readart.asp?url=readartic le&artid=325&bhsh=1050&bhsw=1680&bhqs=1

PROVIDENCE, R.I., Nov. 21 -- Silicon has made its way into everything from computers to cameras. But a silicon laser? Physically impossible -- until now. A Brown University research team led by Jimmy Xu has engineered the first directly pumped silicon laser by changing the structure of the silicon crystal through a novel nanoscale technique.

I also dislike the yellowish light from low-pressure sodium lamps. As I approach an intersection on a street lined with them, I cannot see the traffic signal once it turns yellow: it disappears into the mass of other yellow lights.

These yellow lights also compromise safety, as they hinder you from seeing pedestrians in your periphery at night. The bright blue headlights that everyone complains about glare from are actually great for nighttime peripheral vision. See this article by my colleagues.

Energy is obviously a big concern for lights operated by municipalities, and you can't beat the efficacy of low-pressure sodium. But remember they use this energy off-peak, when it is cheaper. With its long lamp life, an LED solution can reduce maintenance costs enough to offset incremental energy costs, saving taxpayers money.

The other argument against white light streetlights is light pollution. This is better addressed by managing the light distribution, cutting off light that needlessly aims into the sky. Also, using a 3-LED combination to produce white light yields a white that can still be filtered. A graduate student here at the Rensselaer Lighting Research Center just designed an "umbrella" LED outdoor fixture that employs this thinking.

In theory, 3-LED streetlights could also be used for signaling purposes. For example, the city could turn all the streetlights red when there is no parking allowed. Since they don't have a 5-minute warm-up time like low-pressure sodium lamps, they could also flash on and off, in unison or in sequence, perhaps to warn about emergency vehicles or a dangerous chase in progress. You get the idea.

Yeah, I don't quite know why the question is being asked of /. but anywho, glad it is...

I don't particularly trust anything at all I read on "physorg" unless it is also published somewhere else and this search is not boosting my confidence in the article's validity. Other things which make me doubt the clam VERY VERY MUCH are the fact that lightning has a temperature usually not reported in the literature to be above 40-50,000 Kelvin while virtually all fusion devices (which are in thermal equilibrium, as this would also be the mechanism here presumably unless they are proposing some super exotically weird non-equilibrium mechanism) need to attain temperatures in the MILLIONS of K range to even begin seeing neutrons. The fact that they are also claiming that this explains why they see "100 times the background" levels of neutrons during lightning storms is, I think, bordering on the ridiculous. There is a reason it took us until just 2 years ago to discover that lightning emits x-rays, and that is because uhmmm it involves studying lightning at very close range! Interference effects in sensitive electronic equipment caused by the insanely huge magnetic and electric field pulse very close by are extremely hard to eliminate. Until I read the paper, I'll very highly doubt this neutron/fusion "discovery".

Anyway, I think the following line in the submission needs some factual clarification:
"Perhaps more controversially, and yet to be discussed on Slashdot, the NIF has possible plans for a hybrid fusion approach that uses not only deuterium and tritium, but uranium and plutonium as well in what amounts to a miniaturized version of how thermonuclear weapons achieve fusion. Fears are that this could lead directly to micro-H-bombs."

This is a bit of a convoluted misconception. Firstly when NIF (if they ever finish the damn thing) compresses and ignites its DT capsules, they will theoretically produce a gain of something like a maximum of ~50. That is to say, they will release ~50 times more energy than was delivered to them by the lasers which are used to start the reaction and this will result in the emission of a neutron pulse and other thermal and electromagnetic energy in the 10s of megajoules range. This is exactly a replica of a thermonuclear bomb in the lab (without the primary). They ARE "micro-H-bombs", that's the whole idea of the thing. Secondly NIF want's to use uranium and plutonium as reported recently not because they will increase the fusion yield of the micro-bombs but rather because the megabar, megakelvin conditions achievable with NIF will allow the examination of these metals at the conditions which are found at the cores of imploding primaries (and secondary "sparkplugs"). These are called "subcriticals" and they allow the examination of the equation of state" of these metals at energy regimes pertinent to A-bombs without having an actual chain reaction occur.

As for the question "With all the recent discoveries and developments in fusion research, my question for Slashdotters - are we on the verge of something big that will make fusion a practical reality in a much shorter time frame than the often quoted '30 years away, and always will be'"...
Don't count on it. There are lots of very promising and very very exciting ideas out there, but fusion on an economic (and laboratory; ie. not H-bombs) scale is just damn hard to do. The 30 year rule, sadly, still applies. T

Doesn't matter if it's not in a frequency that your rods and cones will react to.

Well, not react to _immediately_. Damage is possible.

It is pretty sad when the dictionary people don't know the real meaning of a word. They say in their introduction that it is merely to fit into a small space. That is not squinching. Dag nabbit. Also, the definition of w00t mis-spells the word, and gives no explanation. It is subtler than what they claim. more useful, and intriguing.

10% efficiencies? What decade are you living in?

Chart

RIT also claims to have resolved one of the biggest fears in immersion -- microbubbles. To solve this issue, the liquid goes through a "double boiling method" before it is introduced to the wafer. In doing so, "the water is de-gassed, where no bubbles exist," he said.
here

I am not sure the indirect drive(you mean laser driven right?) is very promising for much other than the simulation of the high X-Ray fluxes found in nuclear weapons. However, the Direct drive laser implosions done with the addition of the injection of an ultrashort laser pulse at the implostion stagnation time are very promising. We're building one of these ultrashort pulse lines at the OMEGA laser right now.
Even considering the promise this method holds for fusion ignition I can't see how this method will ever be used for producing electricity. It's just not suited for it. The blast from the exploding target destroys the optical quality of your final optics for the lasers after just a hundred shots or so and you're going to need implosion rates of at least a few Hz for practical power generation. Another problem is laser medium heating. In the OMEGA laser you can only take a shot once every hour or so due to the thermal expansion of the Nd:glass medium spoiling the optical quality of the beam. Yet another issue is the abysmal efficiency of the laser itself (barely 1% if I recall), when I said "ignition" earlier keep in mind that means that was done with the actual laser energy hitting the target not the energy used to fire the laser, that's another hundred fold improvement on efficiency (or target gain) you need to account for. I work as a technician on OMEGA and think that it's a really great experimental facility but a power generation plant it never could be.