E2science

My Fellow Noders:

An analysis of the history of science shows that change is exponential, contrary to the common sense "intuitive linear" view.
So we won't experience 100 years of progress in the 21st century — it will be more like 20,000 years of progress at this rate.¹

The new millennium has ushered in many developments in familiar areas of science. While it seems like little can be truly "new" anymore, scientists in recent years have shown us that there is much more to discover about our world and about ourselves.

What we're looking for in this Quest:

• writeups on the subject of any science, e.g., physics, psychology, mathematics since 2000
• thoughtful factual writeups that are well cited where applicable regarding science in the new millenium
• information, thoughts, and/or observations about advances in science from the year 2000 until now
• biographical writeups about scientists who have made contributions to their field since 2000
• reviews of science papers or texts that have been published since 2000
• all submitted writeups must be timestamped within the quest time frame

All submissions for this quest are to be sent to RainDropUp, who will be running this quest with the assistance of Oolong and his nifty god powers.

Your hard work will not go unrewarded-!

All worthy submissions to this quest will receive:

8 XP: One for each year since 2000!

The top five submissions by reputation will also receive:

25 XP, 20 XP, 15 XP, 10 XP and 5 XP, respectively.

This in addition to the piles of upvotes and the potential C!s that also await you.

This quest will begin at 12:00:00 AM on March 8, 2008 and end at 12:00:00 AM on April 8, 2008 server time.
All new writeups submitted to RainDropUp within that time frame will be considered.

The quest is now closed, thank you.

Okay, now get noding!

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¹ Kurzweil, Raymond. The Singularity is Near: When Humans Transcend Biology. Viking: 2005

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And behold:

That Thursday the Universe was curved in the morning and was flat again by afternoon by SyntaxVorlon
Scientific progress: a pessimist's view by Noung
Baby-Step, Giant-Step algorithm by Wntrmute
Cheap Science by lsisus

Potential Barriers and Quantum Tunneling - A Layman's Introduction

Note: This is a layman's introduction to quantum tunneling only. For a general introduction to quantum mechanics, please see Mauler's Layman's Guide to Quantum Mechanics

Quantum tunneling is a concept from quantum mechanics, a branch of modern physics. The concept is explained using the following anecdote.

Suppose there is a hill, a real-world hill which you might walk up, if you were so inclined (no pun intended). Also suppose that three identical balls are rolling at different speeds towards the hill*. Due to this speed difference, each ball has a different energy of motion to the others. As the balls begin to roll up the hill, they also begin to slow down. The slowest ball does not have enough energy of motion to make it up the hill. It slows and slows, and eventually stops somewhere below the top for an instant in time, before rolling back down the hill. The second ball has enough energy to make it to the top of the hill, but no more. It comes to a stop on top of the hill. The last ball has more energy of motion than it actually needs to make it to the top of the hill. So when it makes it to the top, it still has some motion energy, and it rolls over the top, and down the other side.

This is all perfectly normal behaviour for balls on hills - nothing new there. However scientists (more specifically quantum physicists) discovered earlier last century, that when the balls are very very small, something very strange happens.

In the world of the very very small, balls usually behave in the same well-known manner described in the anecdote above. However, sometimes they don't. Sometimes balls which DO have enough energy to roll right up that hill and keep going down the other side, don't make it up the hill. That's weird. Imagine taking a bowling ball, and hurling it with all your might up a gentle hill. You know it's got enough energy to go over the top, but you blink, and when you open your eyes again, the bowling ball is rolling back down the hill towards you.

What's even stranger though, is that in this world of the very very small (and it is the REAL world, inhabited by you and I), sometimes balls which DON'T have enough energy to get up the hill, still do so (and continue down the other side). So it's like your bowling ball comes back out of the return shute, and you take it and roll it ever so gently up that same hill. You know it doesn't have enough energy to make it to the top, but then you blink, and when you open your eyes, there it is, rolling down the other side.

This puzzling behaviour has actually been observed to happen, many many times, by scientists. The phenomenon has been given the name "tunneling", for it is as if the ball (or 'particle' as we call it) digs a tunnel through that hill, to get to the other side. In such quantum experiments, scientists fire very small bullets at very small walls, and sometimes those bullets which do not have enough energy to break through the wall, are observed a short time later, on the other side (where it would seem, they have no right to be!).

Regarding this strange behaviour, I stress that THIS IS A REAL PHENOMENON. It actually applies to everything in the universe, but the chance of it happening to something as large as an elephant, or even a baseball, or a marble, is very small indeed. So small in fact, that it will probably never be seen to happen by a human on this planet. The smaller a thing is, the greater the chance of quantum tunneling occuring to it. Things that you can see with the naked eye are far too big. The kinds of particles to which tunneling commonly occurs can only be seen with special microscopes**.

As a final point, please note that it is probably a good thing that quantum tunneling is almost never observed to happen to everyday objects. It would not be too much fun if that butchers' knife you just placed safely on the table, suddenly tunneled through and found its way into the top of your foot. Of course it might tunnel through your foot as well, but.....well......if you ever see that happen, please let me know.


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* In quantum physics, the hill is known as a 'potential barrier'

** The kind of microscopes necessary to see the particles to which tunneling routinely occurs, are know as Scanning Tunneling Microscopes (S.T.M.). In an ironic twist, the technology which drives the S.T.M., itself relies on the principle of quantum tunneling to operate.

An antigravity device for electrons

There is a very simple way to nullify the effects of the Earth's gravity on electrons, without using any external power source. Simply put the electrons inside a long, thin, vertical metal tube which you have fixed in position. While inside the tube the electrons will not be accelerated at the usual rate

g = - 9.8 m/s²

(minus sign for downwards!), but will float about at near constant velocity (until, of course, they bump into something or fly out of the tube). It helps if you evacuate the tube, since otherwise the electrons will just collide with a molecule in the air very quickly and not float about at all.

Well I could stop here, having added the references

"Gravitation-Induced Electric Field near a Metal", L. I. Schiff and M. V. Barnhill, Phys. Rev. 151 p. 1067 (1966)
(work supported in part by the USAF)

and

"Experimental Comparison of the Gravitational Force on Freely Falling Electrons and Metallic Electrons", F. C. Witteborn and W. M. Fairbank, Phys. Rev. Lett. 19 p. 1049 (1967)
(work supported by NASA)

but you'd be asking "What's this bullshit about"? So, let me explain.

In fact, gravity is still exerting a force on the electrons f_g = g m_e. However, inside the bulk of the tube and (thanks to Poisson's equation) in the space enclosed, there is a (nearly) uniform electric field of magnitude |E| = |g m_e/e| directed downwards. Remembering that the charge on the electron e is negative, the electric force is f_e = - g m_e, thus the total force, and acceleration, vanish to a very good approximation. This was experimentally tested in the second reference. Conversely, a positron in the vicinity of the tube will suffer an acceleration of 2g downwards -- falling twice as fast as usual.

Now you may be saying "Fine, but you just pulled that electric field out of a hat! We learnt in freshman electrostatics that the field inside a conductor vanishes -- method of images and all that -- and here you are telling us that a bit of metal sitting at rest automatically generates a non-zero field?" And this would be a good question.

First, I hope you won't be shocked to learn that physics is a bit more complicated than what gets taught to 18-year-olds. But of course, condescension is not an answer. You have to think about the internal structure of a metal. There are positively charged ions which vibrate gently about the vertices of the crystal lattice and there are conduction electrons that whizz about unimpeded and give the metal its exciting electrical properties.

Now consider the situation where a bit of metal is fixed in place within a gravitational field. The ions are, on average, held stationary by their mutual repulsion. As the conduction electrons fly about, they also feel the force of gravity, so they begin to accelerate downwards on average. They also feel lots of other forces, of course, but to begin with these average out to zero. Very soon the conduction electrons occupy a position somewhat lower than the rest of the metal. Charge separation and polarization have taken place due to gravity! There is now a net negative charge at the bottom of the piece of metal and a net positive at the top. Hence, just like inside a capacitor, there's got to be an electric field in between. In equilibrium, the size of this field is of course exactly that needed to stop the conduction electrons from drooping any farther, viz. g m_e/e. The authors of the first paper of course had a much more rigorous and mathematical derivation, starting from first principles, but this is what it boils down to.

Now this is the field inside the metal; but assuming that E vanishes at infinity, we can solve the wave equation to find the field outside. For an enclosed space surrounded by metal, the solution is just a constant field, the same as the field inside the metal. Inside a sufficiently long, thin tube, it's almost exactly constant except near the ends of the tube.

OK, electrons can levitate for free. How about us?

Alas, in order for the same effect to work for larger bodies, you have to have the same charge to mass ratio as an electron. Even a muon is too overweight and would drop like a stone inside the tube. As pointed out in the second paper, the size of the electric field is about 5.6 × 10^-11 V/m: really quite small. Besides, if even a small chunk of matter had such a concentration of electric charge, it would explode instantaneously under the electrical repulsion. Not good.

However, there do exist antigravity devices, developed by private companies, which have been used for some time by the Pentagon, the CIA and other agencies. They are able to maintain both inanimate objects and human beings at almost any chosen point in space for indefinite periods, without a power supply. The President himself has been known to use luxury versions of these devices. They work by a complicated combination of quantum mechanics and electromagnetism, making particular use of the Pauli Exclusion Principle and Schrödinger's Equation in what must be described as a miracle of engineering. To learn more about these devices, see here, here and here.

From the wild-colored berries in your local produce section to the breathtaking reds and violets of autumn, anthocyanin is the pigment most often responsible for giving plants colors in the spectrum between red and blue. This pigment is notable for both the way it takes part in leaf metabolism as winter approaches, and the sundry ways that it is useful to man.

As summer turns to autumn, trees begin to save up all the nutrients they can in their wood, and discard those elements which are either very common in the environment or too expensive (in terms of energy) to store. Part of this process, known as senescence, stops the flow of chemicals needed for photosynthesis from entering the leaves. This makes sense, as the sun is getting further from the given hemisphere, so even if leaves could survive being frozen the amount of energy they create in photosynthesis would not be as much as that expended in keeping them vital. This blockade causes the metabolic pathways used in photosynthesis break down, and different parts of them become available to take part in producing anthocyanin. Thus, over the course of a few months, less and less chlorophyll is created and used, while more and more anthocyanin builds up in the leaves.

Anthocyanin is stored in the vacuoles of leaves, which serve primarily as a storage place for water. Since it is not kept in the plant's cells, and especially not its chloroplasts, anthocyanin is not at all involved with photosynthesis proper. Instead, it is the chemical's color itself which has a role in leaf metabolism, rather than any of its chemical properties.

One theory says that it acts to protect the leaves (as they become fragile during senescence) from UV damage by absorbing particular wavelengths of light -- with vacuoles located above cells with the highest concentration of chloroplasts, this makes some sense. Another guess is that anthocyanin works to slow down photosynthesis by reflecting the wavelengths of light that are best used by it; leaves are only green because they absorb the non-green sections of the spectrum. Slowed photosynthesis would theoretically benefit the plant by using less of its energy to produce more energy, which because of senescence wouldn't be able to escape from the leaf anyway. One final finding is that anthocyanin light absorption helps stop photoinhibition within the leaves. Photoinhibition occurs when leaf metabolism is slowed or stopped due to high-intensity light hitting leaves which are already damaged -- i.e. leaves which have survived a frost or two and still need to complete vital metabolic steps.

Besides its role in leaves, anthocyanin shows up in fruits and vegetables, lending some of them their attractive coloration. It is actually the pH level of the surrounding water which decides anthocyanin's color, from perfect red at pH < 3, to violet around 7, up to completely blue at pH > 11. Hence, strawberries, tomatoes, and other acidic fruits have a red coloration; neutral plants like red cabbage and grapes are more purple; and basic plants (of which there are comparatively few), such as blueberries, are blue. Some plants do use other colorings, though, like beets, which are red due to a pigment called betalin. Anthocyanin is responsible for the coloration of red wine, and acidification is why wine ages from red-violet to brick red. Notably, a ghetto form of universal indicator can be made by boiling the pigment out of red cabbage -- the color when reacted with an unknown substance can give hints to its acidity.

Finally, some studies seem to show that anthocyanin has health benefits when consumed in reasonable amounts. Neurogenesis in the hippocampus (the only part of the brain able to grow new neurons) is upregulated in rats when they are fed the equivalent of a cup of blueberries per day. This leads to "better memory", exemplified by the rats doing 50% better in repeated maze trials than a control group. Also, the chemical has antioxidant properties and seems to protect against colon and other cancers. Anthocyanin may be responsible for the health benefits of a glass or two of wine per day, as popularized a few years ago by the press.

For reference, here is a table (generated from a chart, so probably quite inaccurate) of anthocyanin content of different fruits and berries, measured by mg / kg:

Blueberry:     3650
Elderberry:     453
Chokeberry:     317
Blackcurrant:   227
Cherry:         186
Grape:          159

(The secret messge of this table is EAT MORE BLUEBERRIES!)

What it is

The Thermo-Depolymerization Process (TDP) is a proprietary technology developed by Changing World Technologies in conjunction with about a dozen other companies, primarily ConAgra (makers of just about every pre-packaged food product not owned by Philip Morris. Yes, even Big Momma Sausage), to convert biological waste into water, minerals, natural gas, and fuel oil. That's right, light, sweet crude that's chemically indistinguishable from No. 2 fuel oil and can be further refined into things like gasoline and kerosene. Essentially, it works like Mr. Fusion from Back to the Future. Take absolutely anything with carbon in it, like milk jugs, medical waste, turkey guts, banana peels, or Sprite and throw it into the TDP machine. Hell, throw the Sprite can in too. It won't make any oil, but it certainly won't hurt. Then, wait a half hour, and oil comes out the other end.

How it works

Nearly every previous attempt to convert waste into energy has failed due to the same nagging problem: water. It takes so much energy to remove the water from virtually anything that the energy recovered by burning the dried refuse almost never makes up for it. However, TDP achieves a remarkable 85% energy efficiency through the clever realization that water is a actually a good thing.

In the first step, the waste product is thrown into a grinder and mechanically broken down into small pieces (or goo, depending on what was thrown in). These pieces are then dumped into the first reactor, which is essentially a giant pressure cooker. The ground waste is mixed with additional water, and then super-heated to somewhere in the neighborhood of 500 degrees Fahrenheit and 600 PSI of pressure. In this phase, long chemical chains (polymers) begin to break down into shorter, simpler molecules. This has the added benefit of killing just about anything that was living in the waste (and survived the grinder, of course), even Bacillus Stearothermophilus spores (which are notably durable) and bovine spongiform enchephilitis (mad cow disease). Unlike other waste disposal techniques, the water is advantageous here because it transfers heat and generates pressure very efficiently, lowering the total energy required to cook (depolymerize) the waste

After this slurry cooks for about 15 minutes, it is rapidly dumped into a decompression chamber. The 500-degree water, now at standard pressure, realizes that it should have boiled off almost 300 degrees ago and proceeds to do so very rapidly. The resulting super-heated steam is used to help heat the next batch of waste, and then can either be reclaimed and used later, or safely dumped like the distilled water that it is. At this point, most of the dissolved minerals fall out as well. In the case of biological products, these are almost always useful as fertilizers. In non-biologicals, they tend to be safe, industrially useful things like metal salts.

The waste, now pre-digested and 90% dry, is transferred into a standard coke oven and is refined using age-old, tried-and-true, oil refining techniques, which include heating it to nearly 900 degrees and waiting for everything to evaporate up the separating column. Natural gas is skimmed off the top and used on-site to heat the reaction chambers. Light oils, heavy oils, and water come from the middle, and industrial-grade graphite comes out the bottom.

The Results

Overall, the process is about 85% efficient, thanks to clever reuse of water and natural gas. Changing World has also compiled a list of interesting statistics for what comes out after putting 100 pounds of waste in:

Plastic Bottles: 70 lbs oil, 16 lbs gas, 8 lbs water, 6 lbs graphite

Municipal Sewage: 26 lbs oil, 9 lbs gas, 8 lbs solids, 57 lbs water

Tires: 44 lbs oil, 10 lbs gas, 42 lbs carbon and metal, 4 lbs water

Used Heavy Oil: 74 lbs oil, 17 lbs gas, 9 lbs graphite

Medical Waste: 65 lbs oil, 10 lbs gas, 5 lbs metal and graphite, 20 lbs water

Is this for Real?

Almost unbelievably, yes. There was a proof-of-concept plant constructed in Philadelphia, PA, and ConAgra constructed a full-sized production plant right across the street from its Butterball Turkey processing plant in Carthage, MO that currently processes 200 tons of turkey-related waste each day. I'll omit the company line about saving the world while eliminating terrorism because hype is still hype, but this process is very real and apparently works as advertised.

What about the Big Oil? You know, the guys that oppress all of the USENET cranks?

Turns out the Oil Industry is thrilled with this technology and is providing millions of dollars in funding for research and development. It turns out that you can take most of the waste from the oil production process (tar sands, used motor oil, grease, and the crud they scrape off the bottoms of oil tankers), dump it into a TDP facility and squeeze just a bit more oil out of it for $10 per barrel, approximately the same price as they would pay a medium exploration company, while giving the finger to the EPA the whole time. Additionally, the oil still needs to be refined, transported, marketed, and sold. Most companies see it as drilling the Alaskan Oil Reserves without all of the messy pipes or environmentalists.

What about Environmentalists?

Changing World estimates that a 175 pound person would result in 38 lbs of oil, 7 lbs of gas, 7 lbs of minerals (mostly rust and chalk), and 123 lbs pure water. Seriously, the process is so clean that the EPA does not even consider the TDP plants to be waste handlers, instead classing them as production.

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References

The Changing World website, for a more sucinct overview, focusing on favorable compairisons and advantages:

http://www.changingworldtech.com

Discover Magazine appears to have the definitive coverage of the topic, along with their usual heady optimism

http://www.discover.com/may_03/featoil.html