Antimail : Science

Carbonite: discovered (or something like it)

AdiOltean — Thu, 15 Jun 2006 17:48:00 GMT

When I was in 7-8 grade I saw (as anyone else) the StarWars episodes. After this experience, I still had lots of unanswered questions. For example, what is carbonite - the black material they used to pack Han Solo in Episode 5? Hmmm... I had that question stuck in my head for a while.

Maybe I don't ask myself these questions today, but I was surprised to find out about a new amorphous form of CO2 - called a-CO2, or amorphous carbonia. This material is nothingg more than regular CO2, but in an amorphous solid state. Let's remember that the carbon's cousin in the Periodic Table (Si) also has an amorphous form of its dioxide, called quartz glass - the special type of glass used in halogen light bulbs. In turn, a-CO2 also forms some sort of carbon-based glass.

At present, a-CO₂ is a curiosity because it cannot be tested or used outside the pressure chamber. The CO₂ that in these extraordinary conditions takes up a chaotic "amorphous" structure, becoming glass, reverts to orderly molecules of CO₂ under decompression.

So far, this material was produced by exposing regular CO2 dry ice to half million atmospheres, but it might be possible that the same material is (meta)stable at room temperature and pressure. But that's an open question, along with the similar question around metalic hydrogen.

(source: Physorg.com)

Poincare's conjecture proof completed?

AdiOltean — Tue, 06 Jun 2006 01:22:00 GMT

A few years ago, I was surprised to see an announcement in Mathworld stating (again) that the Poincare conjecture has been proved. "This time for real" they said. Being skeptical, I waited for more independent confirmation of this result... which never came.

The author of the proof was a respected professor (Dr. Grigori Perelman).

Today, however, I found more news about Perelman and his work. Turns out that the earlier proof was more a set of guidelines on hwo to find the real proof of Poincare's conjecture. In the meantime, the proof has apparently been completed by two Chinese mathematicians.

http://news.xinhuanet.com/english/2006-06/04/content_4644754.htm

   A Columbia professor Richard Hamilton and a Russian mathematician Grigori Perelman have laid foundation on the latest endeavors made by the two Chinese. Prof. Hamilton completed the majority of the program and the geometrization conjecture.

    Yang, member of the Chinese Academy of Sciences, said in an interview with Xinhua, "All the American, Russian and Chinese mathematicians have made indispensable contribution to the complete proof."
    Prof. Zhu at Guangzhou-based Zhongshan University and Prof. Cao at Lehigh University in Pennsylvania co-authored the 300-page paper, "The Hamilton-Perelman Thoery of Ricci Flow-The Poincare and Geometization Conjecture," which was published in the June issue of the journal.

Indeed, the article confirms Dr. Perelman's work, but it gives more clarity on what is proof and what isn't.

"The total length of Perelman's work on the conjecture by the end of 2002 was about 70 pages," said Yang, citing that Perelman raised guidelines for proving the conjecture but not specifically pointed out how to unravel the puzzle.

"Guidelines are totally different to complete proof of theories," Yang said.

As a side note, this mathematical conjecture got a undeserved publicity. The Clay Mathematics Institute says that, if you solve it, you get one million dollars!

Wikipedia is getting pretty good lately

AdiOltean — Fri, 07 Apr 2006 09:57:00 GMT

Maybe I am biased, but I am pleasantly surprised by Wikipedia recently. There is a lot of material coming, at least on the subjects that interest me (I don't know, reading about coffee, tea, scientology, estimation theory, neural networks, anything). An interesting side effect is that I don't buy books anymore on subjects I can read about on wikipedia.

Another thing that caught me by surprise - I rediscovered the pleasure to learn. Now I can go and learn about all these math theories that I skipped in college (because I was always busy typing on those Unix boxes).

First artificial black hole created?

AdiOltean — Wed, 18 Jan 2006 23:31:00 GMT

As an unexpected side effect of an experiment, Horatiu Nastase (of Brown University of Providence, Rhode Island), found something which looks like a black hole:

When the gold nuclei smash into each other they are broken down into particles called quarks and gluons.
These form a ball of plasma about 300 times hotter than the surface of the Sun. This fireball, which lasts just 10 million, billion, billionths of a second, can be detected because it absorbs jets of particles produced by the beam collisions.
But Nastase, of Brown University in Providence, Rhode Island, says there is something unusual about it.
Ten times as many jets were being absorbed by the fireball as were predicted by calculations.
The Brown researcher thinks the particles are disappearing into the fireball's core and reappearing as thermal radiation, just as matter is thought to fall into a black hole and come out as "Hawking" radiation.
However, even if the ball of plasma is a black hole, it is not thought to pose a threat. At these energies and distances, gravity is not the dominant force in a black hole.

[source: BBC]

More news on holographic storage

AdiOltean — Fri, 06 Jan 2006 02:55:00 GMT

Forget the Blu-Ray vs. HD-DVD battle. Think H-ROM. At CES, InPhase gave more hints on this technology in collaboration with Hitachi Maxell Ltd:

InPhase will be the first company to deliver a holographic product for professional archive applications in late 2006. The media for this product will be offered through its strategic partner Hitachi Maxell Ltd. The initial InPhase Tapestry holographic recording device will record 300 gigabytes (GB) of data onto a 130 mm disc with a transfer rate of 20 megabytes per second (MB/s). This is compatible with high-definition television transmission rates, and high-end enterprise computer applications.

Bloom filters and everything else

AdiOltean — Tue, 13 Dec 2005 21:42:00 GMT

If, by some strange and unexplained phenomenon, all blogs on blogs.msdn.com will dissapear, except one, then my preference would be for http://blogs.msdn.com/devdev/

Very interesting stuff. I am already waiting for the next post... :-)

Short gamma-ray burst mystery is solved

AdiOltean — Wed, 05 Oct 2005 22:21:00 GMT

Gamma ray bursts (GRBs) are probably the most violent events that happen today in universe. In a few seconds or less, a gamma-ray burst releases an enormous quantity of energy (10⁴⁴- 10⁴⁶J), which is comparable to burning up the entire mass-energy of the sun in a few tens of seconds, or comparable to the energy emitted by our entire Milky Way does in a hundred years. GRBs are scary - if just one GRB would occur near to us (in our Milky Way for example), it would simply wipe out the ozone layer on Earth, causing life extinction. Hopefully, we will not witness anything like this soon :-). However, it is estimated that a few hundred GRBs occur every day in the observable universe, and not only that - there were GRBs detected at an extreme distance - more 13 billion light-years.

Over the last decades, scientists struggled to understand where they come from, and how far they are. There seems to be two main classes of bursts which seem to behave pretty different: short bursts (which last less than two seconds) and the long ones.

Recently, Don Lamb and his team at University of Chicago found out a solid theory for the generation of short bursts. Their conclusion will be published in the Oct 6. issue of the journal Nature. According to this theory, short-gamma ray bursts are generated by the collision of two (closely-orbiting) neutron stars. This theory is largely confirmed by a significant GRB that was detected earlier this year on July 9, officially known as GRB 050709. There are a few interesting things that came as a consequence of this event:

- First observation of the optical afterglow of a short burst. Afterglows are produced when the jets emitted by the newly formed black hole slam into the interstellar gas that surrounds it. Scientists need these afterglows to track the bursts to their source.
- First identification of the galaxy in which a short burst had occurred. "The observation of that optical afterglow led to the identification of the host galaxy," Lamb said.
- First secure measurement of distance to a short burst. Astronomically speaking, the host galaxy of the July 9 burst has a redshift of 0.16. This translates to a distance of approximately 1 billion light years from Earth, "so it's about 10 times closer than is typical for long GRBs," he said. "That makes short bursts a thousand times less luminous and a thousand times less energetic than long GRBs."
- First determination of where in the host galaxy the burst occurred. It took place in the outskirts of its host galaxy, meaning that it is a very old object. "This alone is very strong evidence that this burst was due to merging neutron stars," Lamb said.

[via PhysOrg]

Thoughts on chirality

AdiOltean — Sun, 04 Sep 2005 10:51:00 GMT

In a recent post that I've missed until now, Eric Lippert describes a simple mental experiment: why a mirror reverses left and right, but not top and bottom. This weird property (called chirality) has a fascinating history, and deep implications everywhere: in physics, biology, chemistry, etc. (Chirality is still an interesting research domain today. For more details see this link)

One example: many chemical compounds, especially the organic ones (including sugar, for example) are tridimensional structures that are not identical with their image. These compounds are called enantiomers:

As a direct consequence, there are two different types of sugar which are almost identical (even in taste), but not quite. Actually, it's more complicated: a sugar molecule is based on a glucose-fructose pair, and each of these molecules have their own variations. For example, there are two forms of glucose: D-glucose and L-glucose, and so on. An intriguing fact is that only the D-glucose is present in living organisms, which makes the L-form interesting. This hides a much deeper problem: there is a high degree of chiral assymetry in the biological world. The helix-form of the DNA or example, is strongly assimetrical:

By the way, did you notice that no matter how you rotate a spring, the helix always goes the same direction? No matter how you look, the helix looks the same. In the case of DNA helix, if you look from the top to the succession of aminoacids, they always go in clockwise-direction!

Bringing on Sci-Fi experiments

Enough with reality... let's walk on the wild side. Let's just assume that there is an "invertion machine" that would invert any physical object and produce its mirror form. Even more, let's assume that I succeeded to build some sort of "tunnel" which you can walk in on one end, and come up completely inverted on the other end!

This experiment would have all sorts of weird consequences. For example, let's assume that I am going to be inverted. After this experiment everything around me looks completely the other way around. First, I would observe that the cardinal directions are now interchanged. Sun is going the "other way around" - the sunrise it's happening now at my definition of West (but everyone would insist that this is East, in fact). Any text will look like in the mirror", cars would be driven on the right side, etc. You can "peek" this reality by just looking through a mirror, of course.

A side note: some people went even further - a scientist (I forgot his name) built a special set of glasses that inverted the light, and wore them for several days. At first, he had a terrible headache, because everything was the "other way around". But after a while he got used to the new world pretty quickly. And of course he had a similar lag when we gave up in using the special glasses...

Inverted life

But much more severe consequences might happen because now our biological world will enter in contact with living things from "beyond the mirror". Take bacterias, for example: their inverted DNA will make them immune to the current antibiotics!

So if I go through an invertion machine, I will be exposed, first of all, to various forms of the "inverted" forms of life (which can cause me unknown types of diseases). Not only that but, as a host of all sorts of organisms, I will be the one that brings the inverted forms on earth for the first time! Remember that normal microorganisms in the word will appear inverted for me, and microorganisms that I host (and which appear normal to me) will appear inverted to the world. Who knows if some species of bacteria (like Escherichia coli) will cause a disaster if present in inverted form.

So, this little experiment can have disastruous consequences. Or maybe no consequences at all; who knows... Nobody tried to "mix" natural life with inverted life.

Hanford Site: now open for public tours

AdiOltean — Sat, 02 Jul 2005 10:38:00 GMT

I am not sure how I became fascinated about nuclear engineering in the last months. But, anyway, in the Washington state we have a unique nuclear reservation - the Hanford area, where the first nuclear reactors were put in operation more than fifty years ago. This is the place where Edward Teller and Enrico Fermi noted for the first time effects operational like the Xenon poisoning (which can cause a reactor to stall after few hours of operation, and then resume operation).

Anyway, I just noted that the site is now open for public tours: see this link for details. Here is a quote:

For the first time since the events of September 11, 2001, the Department of Energy is making portions of the Hanford site - where cleanup is taking place - available for public tours on Friday, June 24, and Saturday, June 25.

Visitors will be driven from Richland, Wash. through the Hanford Site on a route that is designed to follow the process used to produce plutonium for the nation's defense and explain current cleanup efforts, including:

Hanford's 300 Area, just north of Richland, where fuel was manufactured for irradiation in Hanford's reactors
The original Hanford town site
Former Hanford and White Bluffs town sites
Production reactors along the Columbia River, known as Hanford’s 100 Area, where nuclear fuel was irradiated. Activities in that area today are primarily focused on ‘cocooning’ former reactors and cleaning up waste sites. This portion of the visit will include a walking tour of B Reactor, the world’s first large-scale plutonium production reactor.
Hanford’s central plateau, or 200 Areas, where irradiated nuclear fuel was processed to recover plutonium. This is where most of the waste that resulted from processing is located, along with a number of current activities to clean up the waste.

Unfortunately, I missed this tour. Argh... Maybe next time. (No, really, I am serious!)

Nuclear fusion to be probed in France?

AdiOltean — Tue, 28 Jun 2005 00:16:00 GMT

ITER is one the largest physics experiments ever attempted. In short, it should be the first research fusion reactor that actually will succeed to produce power. ITER attempts to operate in the 500 MW (thermal) range, which is around the output of a small nuclear reactor.

If you look at the design or operating parameters, everything it is just mind-boggling. The torus dimensions are just huge - 12 meters in diameter, and six meters height. In total, a little less than 1000 cubic meters of plasma (mostly, rarefied tritium + deuterium gas). The plasma is kept at 100 million celsius degrees, yet at a meters away, there are huge superconducting coils that are cooled down to just a few degrees above absolute zero.

If you are concerned about safety - this is much safer than a fision-based reactor. The fusion reaction will abruptly stop as soon as the carefully controlled conditions are not met anymore. There are no more issues around super-criticality, etc. that are so sensitive for a normal nuclear reactor.

It's total cost would be around 3 billion dollars, and there are several countries that are helping with this project, notably EU, Japan, US and others. This all looks interesting, but it looks like the participating countries can't decide where to build this thing. There seems to be a fight between Japan and France for the last months, and there are apparenly some recent rumors that the reactor might be built in France.

P.S. Maybe my calculations are wrong. One gram of Ra-226 has one curie, and a half-life is 1600 years. One gram of Tritium (H-3) has 12 years half-life will have 1600/12 * 226/3 = 10,000 Curie. Now, since there are maximum 450 grams of H-3 in the reactor at any time, if it completely blows up you get around 4.5 millions Curie in the atmosphere, which is much less than from an fision-based reactor. It's still a significant number, though.

Innovative database technology coming from... High Energy physics

AdiOltean — Wed, 18 May 2005 01:36:00 GMT

How would you design a database if you have to store gigabytes of new data every second?

A particle accellerator generates a huge amount of data, that needs to be stored in real-time on very large storage systems. Usually, the offline analysis phase happens weeks later. But in these days, the quantity of data is so large, and the query patters so diverse, that you have also to create the database indexes in real time! The team at Berkeley Lab performed some interesting optimizations in this area:

http://www.physorg.com/news4137.html

How does a four-dimensional world look like?

AdiOltean — Mon, 16 May 2005 09:54:00 GMT

Eric Lippert is running an eye-catcher series on High Dimensional spaces (see here part one and two). Which got me thinking. The classical laws of Optics work can be easily generqalized to N spatial dimensions. You could easily imagine things like refraction point of a material, lenses, sources of light and so on in a four-dimensional space for example. And also more advanced things like refraction, diffusion, and even the Fresnel effect!

I am sure that there are relevant images on the web, but I can't seem to find them. Any ideas?

Humor: Tom Lehrer in The elements

AdiOltean — Sat, 07 May 2005 04:25:00 GMT

It's a classic...

http://www.privatehand.com/flash/elements.html

You might already know it, especially if you love (or hate) chemistry. If not, enjoy!

Remembering Chernobyl

AdiOltean — Tue, 26 Apr 2005 20:23:00 GMT

It was exactly 19 years ago. Soviet Union was trying, at least in theory, to reach the perfect communist society. Since May 1 (Labor day in USSR) was close, the staff at Chernobyl nuclear plant was rushing to complete one more final test that would serve as a proof that their power plant would survive a sudden energy blackout. The goal of the test was to show that the nuclear reactor #4 can be "rebooted" in the absence of any external electrical energy sources.

The test

Nobody knew that the test (as designed mainly by Nikolai Fomin, the plant chief engineer back then) was pretty flawed as it required the reactor to work outside its designed operational limits. What the designers did not know was that for the duration of the four hour test, the reactor was also in a highly unstable state, due both to its positive void voeficient (i.e. nuclear reactivity goes up when steam is formed in the cooling water) and positive temperature coeficient (i.e. reactivity increases with temperature). Sadly enough, this information was actually classified back then, in the true spirit of the communist society. Not even the people operating the plant had access to this information.

There were also a number of violations in operating procedure. First of all, the test required the automatic control system (LAR) to be switched off. Second, at the initiative of the chief plant engineer, the emergency core cooling system was also turned off for the duration of the test, based on the fear that it will be dangerous if the cooling water from the emergency tanks enters into the hot reactor. Finally, both emergency diesel generators were turned off, in order to simulate a "pure" experiment. Even with these stunning violations, people were confident, since such tests were conducted previously with success, so nothing could wrong this time, right? The reactor was generally viewed as safe as a rock.

During the test, however, several things went wrong. First, with LAR switched off, the operators were unable to manually maintain the reactor power under the devised limits. The normal (operating) power was around 3200 MW thermal, which meant about 1000 MW of electrical energy produced. The power required during the test was much lower - a few hundred MW, simulating the reactor startup conditions. However, the reactor went to 10x lower than expected - 30 MW thermal.

At this point, theoretically, the reactor should have been shutdown, and a regular start-up been scheduled the next months. But an immediate restart was attempted as a quick "cover-up" for the earlier mistake. But that didn't really work. The start had been somewhat impeded by a known fenomenon called Xenon poisoning. (Xe-135 is a fission decay product that is a strong neutron absorber. In normal operating conditions, the produced Xe-135 is held in check by the neutrons produced in excess. But during shutdown, the concentration of Xe-135 dramatically increases making the reactor restart impossible. But since its half-life is about several hours, the reactor restart will be again possible after a few hours. More interesting details here).

The test went on, under the impatient management of the deputy chief engineer - Anatoly Dyaltov. He ordered that, one by one, the remaining control rods to be retracted from the core, to move the reactor back into the operating position. Anyway, the rods were withdrawn until the reactor was raised at approx. 200 MW thermal, with very few remaining control rods in the core. But he didn't know that at this point the reactor was in extremely unstable state. After few minutes, everything looked stable and, around 1:23:00 AM, he decided to start the actual test. As we briefly mentioned above, the test required that the massive turbogenerators would be started on using only the hot steam produced from the core. But when the turbogenerators were connected in the flux, however, the flux of incoming water started to decrease. Bubbles of steam started to form into the core coolant, which caused sudden increase of power due to the positive void coeficient.

The operators noticed this, and at 1:23:40 AM they tried to manually shutdown the reactor. However, when the safety rods were introduced in the core, the reactivity actually increased for a few seconds due to a fault in the design of the rod geometry. This was the final blow that brought the reactor in a few seconds to around 30,000 MW (thermal). The huge generated heat caused several large explosions that blew away the 1000 ton reactor lid and destroyed the top of the building. Due to the lack of containment, the core was now directly exposed to atmosphere, releasing hundreds of millions of Curie in the environment for the next days.

The reactor was "shutdown" in the next weeks, by dumping sand and lead on it. At the end, only around 10% of radioactive material was left in the building, the rest was released in the meantime by the explosion or the intense fire.

Consequences

31 people died, mostly firefighters that heroically fighted with the fire on the roof of the building. Most of the operators died too. Hundreds of people were hospitalized, many of them dealing with acute radiation problems. But the long term consequences were much more severe. Hundreds of thousands of people were relocated from the the affected area, with minimal support from the government. They had to start their life from scratch, with no resources, no past.

[update - corrections]

Puzzle: do you know chemistry?

AdiOltean — Fri, 22 Apr 2005 09:36:00 GMT

Here is a very nice puzzle - But unfortunately you have to ressurect a little chemistry knowledge to fully appreciate it...

You have two identical test tubes. Both tubes look identical - they both contain colourless, odoreless, aqueous solutions. But someone told you that one of them contains a solution of sodium hydroxide (caustic soda), and the other one a solution of potassium aluminum sulfate (potash alum).

How do you quickly tell them apart?