Meteor Attack!

I noticed this news yesterday from the Daily Telegraph:

14-year-old hit by 30,000 mph space meteorite
A schoolboy has survived a direct hit by a meteorite after it fell to earth at 30,000mph.

Gerrit Blank, 14, was on his way to school when he saw "ball of light" heading straight towards him from the sky.

A red hot, pea-sized piece of rock then hit his hand before bouncing off and causing a foot wide crater in the ground.

Wow!

...

Right.

Okay, the subtitle of the article is "A schoolboy has survived a direct hit by a meteorite after it fell to earth at 30,000mph." The first question that pops into my mind is: how on Earth does the boy or the newspaper know that the meteorite is going at 30,000 mph? That's about 10,000 m/s, which is damn bloody fast. It can cover the length of Singapore in about 4 seconds. And second question: direct hit? Even if it's granular sized, the kinetic energy and momentum involved would've blown up his hand. And then the article also threw up some numbers which, if you'd think about it, is highly fishy.

Definitely, either this is a sham that made it to the news, or there are gross inaccuracies in that article, which is rather shameful because The Daily Telegraph is somewhat a reliable source of news. I searched around and found a more reliable analysis of this article by someone from Discover magazine:

A boy claims he was hit by a meteorite

Okay dudes, all the more reason to carry an umbrella even if it is not raining.

Building a Space Elevator

Japanese scientists and engineers have set their sights on one of the most challenging tasks of a hard science fiction concept: the space elevator.

The space elevator, first popularised by Arthur C. Clarke in his novel Fountains of Paradise (an excellent read, if anyone's interested), appears to be a highly inexpensive way to travel to space, or at least to low-orbit space. It is a popular idea in science fiction and has also made it to scientific journals, being quite solidly based in proper physics.

The basic idea is that we connect a point on Earth to a geostationary satellite directly above it. This connection can be a tower (which is not feasible due to the weight) or merely cables that pulls a lift between these two points that are stationary in the reference frame of an Earth-bound observer. However, if we consider the Earth base as an anchor point and the cables plus satellite as a system, this system will start to swing sideways because its centre of mass is not in geostationary orbit, so we have to extend and attach some sort of mass beyond the satellite to counter this. In the novel, the construction started from the satellite and went both ways - up and down - simultaneously in such a way that the centre of mass stays in the orbit.

Of course, the cables will have a Coriolis force acting on it. On top of that, the length of the cable implies, even if it is of low density, a very strong tension throughout the cable. Therefore, this is the leap in this science fiction concept: a lack of such lightweight yet awesomely strong material. However, these Japanese scientists seem to have the solution: carbon nanotubes. But I think there is still a huge challenge since carbon nanotubes may not be strong enough yet, and mass production of large scale nanotubes are nowhere near a reality. Of course, this still does not take into account the multitude of engineering feats that has to be performed.

This space elevator, if ever built, will serve as a very cheap mode of space travel. Not only does it save the need to launch a space shuttle that gobbles fuel like an F1 race car, it also conserve energy just like a typical lift: as a lift comes down, it'll pull a weight of slightly smaller mass upwards, which will in turn act as a gravitational battery when the next lift goes up. It will also cut down the cost of space travel (to beyond geostationary orbits) by moving the launch site to the satellite, which bypasses a tremendous part of the energy consumption.

Personally, I'm sceptical about the plausibility of pulling this off. The material of the cable remains the greatest challenge, and I think carbon nanotubes are still way off from being a satisfactory material for such a construct. Moreover, as witnessed by the multiple failures in the Large Hadron Collider (LHC), new toys present new problems of their own, and this space elevator can be pretty disastrous if it fails in the wrong way. On top of that, such grand projects are bound to be costly, and I doubt Japan can pull it off by themselves. The LHC is funded by a collection of wealthy nations; I'm not sure if the space elevator will be any less.

Well, on the bright side, even if I'm wrong, at least there's a chance I can visit space in an environmentally friendly way. And what's more, the base station on Earth has to be on the equator (an off-equator geostationary orbit projects a sinusoidal curve on Earth's surface), so there's a chance the base station is in Singapore. If we reclaim southwards furiously enough, that is.

Quantum Photosynthesis

According to Physorg (arrived via Slashdot), our understanding of photosynthesis has been wrong all the while. According to a paper published days ago in the esteemed Nature journal, the photosynthesis process actually involves quantum coherence.

From the Physorg article,

"We have obtained the first direct evidence that remarkably long-lived wavelike electronic quantum coherence plays an important part in energy transfer processes during photosynthesis," said Graham Fleming, the principal investigator for the study. “This wavelike characteristic can explain the extreme efficiency of the energy transfer because it enables the system to simultaneously sample all the potential energy pathways and choose the most efficient one.”

They aren't the ones to first propose the idea, but they provided the first direct evidence of it.

Said [Greg] Engel, "[...] While the possibility that photosynthetic energy transfer might involve quantum oscillations was first suggested more than 70 years ago, the wavelike motion of excitation energy had never been observed until now."

As I understand it, it appears that there is coherence between the donor and acceptor molecules due to impinging photons, resulting in very rapid energy transfer. However, this is not my area; I believe this belongs to either the realm of biophysics or quantum chemistry. Nonetheless, from a physics perspective it is very interesting to see quantum mechanical processes manifesting all around us.

If this is indeed the case and the underlying theory can be worked out, it will be critical in our knowledge to build highly efficient solar cells. But this also means that the simple chemical interpretation of photosynthesis has to be thrown out of the window, as thus from secondary school or JC textbooks. Ah well, at least next time there's a need to cut the syllabus, it will be clear which one will go.

And as a last thought, if photosynthesis is a quantum mechanical process, then does that means that the leaf has both photosynthesized and not photosynthesized?

NUS Open House 2007

This year's Open House booth for the Faculty of Science was at the LT27 Foyer, which in my opinion is a much better location than last year's S16 Foyer, which was so lacking in space that it looked like the inside of MRT trains during peak hours. However, probably because of the larger space, the place looked emptier, but I somehow had a feeling that there were less people this year.

In any case, Physics Department maximised the use of the space and scattered our tables and experiments over the place. Here are a few selected photos of the events.




The booth by the Physics Department. It shows the three main tables and part of the astrophysics equipment. Another table is not shown in the picture.




Talk by Prof Sow in LT28.




Discussion among the brains of the department. First from the left is my supervisor Dr Yeo Ye.




Telescopes, posters and images (on laptop) from the astrophysics arm of the department. For the new batch there is an additional specialisation in astrophysics.




Mirage bowl. It's a new one as compared to last year's, which was full of scratches, so the image of the pig as seen here is clearer.




Resonance bowl. You can see the 内功 of the demonstrator from the jumping and vaporisation of the water. Just kidding... the vapour is a result of me adding liquid nitrogen into the water.



Taking advantage of the space, we had the angular momentum spinning chair this year. The spinning rate can slowed down or quickened depending on the moment of inertia of the person (adjustable by holding out or tucking in the weights respectively).



This year's theme is sponsored by Lego. And large Lego pieces were given to each department to construct various models. This is a chair I've constructed. It goes to show why I should not be in architecture or civil engineering.

Of course, the department's trademark show, the superconductor, is down at the centre stage of the show, but since I've talked about it extensively last year, I shall spare everyone of the repetition.

However, I had two thoughts about this Open House. First was a comment posed to me by a mother. She commented that "physics must be very hard". My immediate response then was, "not really, but as long as someone puts in effort, he will be able to do it well." That was the truth, of course, but thinking about it, I could've responded in a much better way, namely, that there is no "easy" or "hard" courses; any course can be easy or hard. What's more important is the interest in the subject, which will probably determine what is easy or hard more than any other indicators.

This led me further to ponder about why many people have the perception that physics is hard. Does it have anything to do with how physicists appear to the general public (i.e. the public portrayal of the likes of Einstein, Bohr, Feynman etc.)? Or is there some fault in the local education system that causes people to dislike physics? After all, there is a drop in the proportion of Singaporeans in the physics cohort, replaced by enthusiastic and motivated students from China and Malaysia. I think this question deserves to be addressed in more detail.

Another thought about the Open House was a diagram in the Science brochure (which I cannot find right now). It's like a three-piece flow chart, showing Singapore's economy developing from a labour-based economy to a technical-based economy to a knowledge-based economy. An era was attached to each economy, with the first being from 1950 to 1970, the next from 1970 to 1990 and the last being 1990 and later. (All these are based on my memory and can be wrong. But I just need an approximation to illustrate my point.) This is fine, but then with each economy was also attached a "qualification". I can't remember what was placed for the first (probably something like unskilled labour). The third was a science degree. For the technical-based economy, the 1970 to 1990 era, a "Engineering degree" was attached. While I understand what the brochure is trying to say, I think it gives an unfair description of an Engineering degree.

Firstly, what the diagram is trying to say is that the economy is moving from depending on unskilled labour to specialised technical skills in the earlier years, and now from technical skills to analytical skills. While a degree in Engineering equips one with a specialised skill, it hardly means that it is stuck with a "technical-based" economy. I could be wrong, but I think the Faculty of Engineering would've taught its students on being flexible with their knowledge, so that they won't be tied down to a specific skill.

Well, so that's for NUS Open House 2007 for Science!

Gmail the Organiser

Even as I plunge into my ISM on open quantums systems, I am keeping a lookout for the latest journal articles published on the Los Alamos National Laboratory pre-print archive, which is where almost all the final drafts of articles to be submitted to journals are uploaded. This is so as to keep track of the latest developments in that field and get an idea of the kinds of project I can do.

However, the archive, being a site for pre-print, sees a whole lot of articles everyday. Even in the sub-section for quantum physics alone, there is on average ten articles a day, out of which I can usually find one or two that is related to open quantum systems. Add that up over days and weeks and months, I think I will have a substantial collection of articles at my disposal. Of course, the problem then comes: how do I organise all these journal articles and, especially, how to know what each of them discusses about? The abstract should give one an idea of what the paper discusses, but if you have a hundred articles, reading through all the abstracts can be quite maddening.

That's when Gmail comes in handy because of its features. One, it uses labels, which means I can attach different keywords to each article, making a search on a particular idea easier. Two, it has an amazing amount of space, so no worries that I'll max out the space given. Three, it's not housed in my computer, so unless Googleplex collapses, I can be assured that I won't lose the articles. Four, Gmail will be accessible to anyone who needs to search for articles in open quantum systems, e.g. my supervisor.

Right now, the Gmail account is still empty... because I have yet to go through any of the articles I've collected in details yet. But I cannot foresee any troubles with this plan. Yet.

Nuclear Power in Question

In the 80s and 90s, nuclear (fission) power was greatly shunned by the public, with many advocacy groups called a complete ban of it. This was partly due to the proliferation of nuclear weapons as well as several disastrous nuclear accidents.

In recent years, nuclear power is back in the limelight, not as the object of criticism but as a possible alternative to the growing energy crisis. Considering that it is clean (no carbon emission) and its fuel not running out any time soon, it looks more and more promising as an alternative candidate with the rising price of oil and environmental concern with coal (for example, a coal-burning power plant releases radioactive products into the air, exposing people to radiation several times more than a fission power plant). Other promising alternatives like solar and nuclear fusion are still not practical.

However, not all is smooth for nuclear power. The journal Nature carried a recent news article (obtained via Slashdot) that demonstrated past methods in disposing nuclear waste is not as safe as previously thought.

Quoting from the article,

A fast-moving alpha particle knocks into hundreds of atoms in its path, scattering them like skittles. Worse still, the radioactive atom from which the particle comes is sent hurtling in the other direction by the recoil. Even though its path is even shorter than that of an alpha particle, the atom is much heavier, and can knock thousands of atoms out of place in the ceramic.

All this disrupts the crystalline structure of the ceramic matrix, jumbling it up and turning it into a glass. That can make the material swell and become a less secure trap. Farnan says that some zircons that have been heavily damaged in this way by radiation have been found to dissolve hundreds of times faster than undamaged ones. So if the ceramic gets wet, there could be trouble.

There are, of course, other concerns, such as how one can lower the chances of nuclear accidents like the Three Mile Island accident. And then of course there's always the controversy linked to nuclear weapons. I cannot, however, comment from a technical point of view, since my course on Nuclear and Particle Physics has only started, but I guess that even after that, my knowledge is still too insufficient.

Science of Santa

North Carolina State University has published a news release that argues the scientific viability of Santa Claus, backed by the university's professor of mechanical and aerospace engineering.

From the article, Santa and his elves have

advanced knowledge of electromagnetic waves, the space/time continuum, nanotechnology, genetic engineering and computer science easily trumps the know-how of contemporary scientists

and how they used scientifically fantastic innovations to carry out his duties.

Naturally, this post is written somewhat in a casual manner, ignoring the technological viability of some of methods used. It is pretty interesting to see imagination and science explain what appears to be impossible phenomena.

However, impressive explanations like

a sophisticated signal processing system filters the data, giving Santa clues on who wants what, where children live, and even who’s been bad or good

sounds pretty Nineteen Eighty-Four to me...

Fastest Spinning Black Hole on Record

Just had my SP2172 presentation on Monday at 1600. And then, an article closely related to our project appeared just less than 24 hours later.

This is especially related since during the Q & A session, people asked on the existence of a theoretical limit on how fast a black hole can spin.

As usual, I emphasized the more relevant parts.

Spinning black hole is fastest on record
15:39 20 November 2006
NewScientist.com news service
David Shiga

A black hole has been found to be spinning faster than ever seen before, a new analysis suggests. The finding supports the idea that only fast-spinning stars can collapse to create powerful explosions called long gamma-ray bursts.

To measure the spin of black holes, astronomers measure the size of the discs of matter that orbit them. A spinning black hole drags space-time around with it as it spins, boosting the speed of matter in orbit around it. That allows the matter to orbit closer in without getting sucked into the black hole itself – so the faster a black hole spins, the closer matter can stably orbit around it. [Pandemonium: technically, this means that the radius of the event horizon (or the point of no return), becomes smaller as the black hole spins faster; this agrees with our theoretical analysis and computer simulation.]

Watch an animation showing the difference between spinning and non-spinning black holes.

But the innermost edge of this disc is too small to see directly. So previous measurements of black hole spins have had to make assumptions about properties such as the tilt of the disc to Earth's line of sight.

Now, astronomers have measured the spin of a black hole with a new method that requires fewer assumptions. The team was led by Jeffrey McClintock of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, US.

Hot gas

McClintock's team examined a black hole in our galaxy called GRS 1915+105, which lies about 36,000 light years away. Matter gets hotter as it gets closer to the black hole, so the team used X-ray observations from NASA's Rossi X-ray Timing Explorer to measure the temperature of the gas in the disc.

They found the innermost stable orbit around GRS 1915 is so close that the black hole must be spinning at nearly 1000 times per second – the fastest ever recorded.

"The application of this to understanding black holes and black hole physics are really quite important," McClintock told New Scientist. "It’s the most exciting thing I've worked on."

But a second study of GRS 1915 suggests that the spin could be lower, according to an analysis of the same RXTE data by Matthew Middleton of the University of Durham, UK, and his colleagues.

Stellar collapse

Chris Done, a member of Middleton’s team, says their analysis suggests the spin is “substantial but not extreme”. They argue that X-rays scattering off of electrons in the disc make the temperatures appear higher than they really are. This gives the illusion of a closer-in disc, and therefore a faster spin for the black hole, they say.

But if McClintock's team is right, the black hole is spinning at 98% of the theoretical maximum rate, which is calculated by how fast stars can spin before they collapse to form black holes.

The observation provides support for the idea that gamma-ray bursts – fleeting but powerful explosions – are produced by fast-spinning stars.

In this scenario, a black hole forms at the centre of such a fast-spinning star and some of the remaining stellar material forms a disc that spirals into the black hole.

High spin

The interaction of the black hole and the disc produces jets, which emit copious amounts of gamma rays. But the star has to be spinning very quickly when it collapses for this disc to form, and some astronomers have expressed doubt that stars would be spinning fast enough at this stage in their lives.

The new research may quell some of those doubts. "It says sometimes stars do find some path for dying with a huge amount of rotation in their middle," says Stanford Woosley of the University of California in Santa Cruz, US, who is not a member of the team.

Christopher Fryer of the Los Alamos National Laboratory in New Mexico, US, who is also not on the team, agrees. He says it is "strong evidence that nature can get the high spin rates in stars to produce gamma-ray bursts".

McClintock says he hopes that analysing similar observations for other systems will allow them get spin rates for half a dozen more black holes within the next two years. "We're going to apply it as widely as we can," he says.

Journal references: The Astrophysical Journal (vol 652, p 518)

Monthly Notices of the Royal Astronomical Society (DOI: 10.1111/j.1365-2966.2006.11077.x)

Sometimes you just wonder why such related articles cannot be published a day earlier.