Wikipedia:Reference desk/Archives/Science/2010 September 6

= September 6 =

Skyscrapers
I was reading the articles Mile-High Tower and Dubai City Tower. Dubai City Tower will be 2,400 m high with 400 flrs which will be a remarkable achievement. I was wandering whether it will be possible within next 30 yrs to build a building which will be the tallest structure on Earth, i.e. taller than Mt Everest? I'm not expert of skyscraper technology, do those who are knowledgeable in this area see such progress in the near future? --Galactic Traveller (talk) 02:07, 6 September 2010 (UTC)


 * Highly unlikely. Skyscrapers become feasible when the value of land (such as in a central business district) becomes so high that it is economically feasible to construct a very high building.  The cost of a skyscraper increases in proportion to its height to some exponent greater than one.  (For example, perhaps the construction cost is proportional to the height to the exponent five.  That would mean doubling the height of a proposed building would increase the construction cost thirty-two times.)  So a super-skyscraper would only become feasible in a district where the value of land was extremely high.  And when the cost of doing business in one business district becomes conspicuously high, another business district emerges nearby, with much lower costs.  Probably no business district on Earth would justify a skyscraper approaching 2400m, and certainly not one as high as Mt Everest.


 * So that begs the question Why do architects do preliminary designs for super-skyscrapers? I guess it is an interesting design study.  Getting your plans published would do good things for your reputation if you were an architect.  But would anyone be willing to finance one of these super-skyscrapers?  Unlikely.  I notice the X-Seed 4000 and Dubai City Tower are presently nothing more than eye-catching ideas.  Dolphin  ( t ) 03:36, 6 September 2010 (UTC)


 * Building a super tall is to some extent also a way to show off and announce your presence to the world hence why it tends to be more common in developing countries recently. However it remains difficult to imagine anyone would build a 2400m building in the near future. I have no idea if the DCT was ever really intended to be a serious design proposal or just a design idea (like the X-Seed 4000 was), but notably the design was released in August 2008 which was still the early days of the current economic problems (most of the work of course likely been a while before) and notably before Dubai's problems which resulted in them effectively being bailed out by Abu Dhabi several times   which is generally believed to be a key reason the largest supertall they do have was renamed from Burj Dubai to Burj Khalifa. BTW did you read the X-Seed 4000 article which notes "Unlike conventional skyscrapers, the X-Seed 4000 would be required to actively protect its occupants from considerable air pressure gradations and weather fluctuations along its massive elevation." Nil Einne (talk) 04:08, 6 September 2010 (UTC)


 * I presume the question is basically whether it will be technically feasible, not whether anybody will have a reason to do it. My impression is that theoretically it is feasible, but it would have to make use of exotic materials quite a bit stronger than steel per unit weight, materials such as carbon nanotubes or even diamond. Looie496 (talk) 05:45, 6 September 2010 (UTC)


 * The existence of Everest, (or, for a greater challenge, Mauna Kea) is proof that it is possible to construct such structures from ordinary rock... if a large enough footprint is permitted! We'd need a more stringent set of specifications to determine how tough a material is actually required. Wnt (talk) 07:25, 6 September 2010 (UTC)


 * My understanding is the the lithosphere underneath Everest is unusually thick, and Mauna Kea is located over a mantle hotspot. It wouldn't necessarily be possible to place something like that at an arbitrary location without it sinking into the earth. Looie496 (talk) 18:42, 6 September 2010 (UTC)


 * I'd also suggest that as well as the sheer technical challenge there is a physiological aspect. Even if the building could be built, would it be usable?  Altitude sickness could be a real issue, as could regular compression/ decompression.
 * ALR (talk) 15:48, 6 September 2010 (UTC)


 * Not exactly related, but you might enjoy reading the Space elevator article. APL (talk) 20:23, 6 September 2010 (UTC)
 * In line with APL's comment, they can tether the apex of the tower to an orbiting satellite to ensure further stability.  DRosenbach  ( Talk 12:13, 7 September 2010 (UTC)

MOSFET?
I have an electronic component labelled K3797. I think it's a n-type MOSFET transistor. The resistance between the source and drain terminals decreases to nearly 0 immediately after I apply 9V to the gate, but takes about 10 seconds to return to its previous value after I replace the 9V with ground. In fact, for the first 3 seconds, the resistance doesn't even change measurably. Why does this happen? I always thought transistors responded immediately, not after 10 seconds. --99.237.234.104 (talk) 03:14, 6 September 2010 (UTC)


 * Is the ground rail really at ground or is it just a copper track that does not connect to anywhere or is it via a capacitor etc?--Aspro (talk) 08:43, 6 September 2010 (UTC)


 * Could you please post a picture of the component next to a ruler? Why Other (talk) 22:30, 6 September 2010 (UTC)
 * Googling the part-number confirms it as N-type FET. Many of those early hits are to its technical data sheets, so you can compare diagrams of it to what you have (including package-format, lead layout, size, other markings, etc.). DMacks (talk) 05:17, 7 September 2010 (UTC)


 * It's just a copper track that connects nowhere. When I use a real ground--the negative terminal of a battery, or of an AC adapter--the LED dims immediately.  Why is this the case when there should ideally be no gate current in the first place?  --99.237.234.104 (talk) 23:11, 7 September 2010 (UTC)


 * The gate of a MOSFET is separated from the channel by a thin and effective insulating layer.  The charge produces a  field-effect (hence mosFEt) which allows  it to switch on.  This field-effect  does not need current to flow -just a large enough potential. It dose not need much track to provide enough capacitance to hold a small charge.  The high insulation means, the charge leaks away very slowly. This is very useful in applications where one has a very small signal which a lower impedance device would quench.  Does that answer your question? --Aspro (talk) 15:10, 8 September 2010 (UTC)
 * So when a positive voltage is connected to the gate, the insulating layer becomes charged, and it is this charge which attracts electrons, repels holes, and creates a conduction channel. When the gate is then connected to a real ground, the charge leaks away quickly and immediately closes the conduction channel; when it's connected to just a piece of wire, the charge can't leak away as quickly, and the conduction channel takes a long time to close.  Is this right?  --99.237.234.104 (talk) 06:17, 9 September 2010 (UTC)
 * More or less but it is not the insulator that is getting charged, although it might allow some of the charge to slowly leak away as it is not perfect, neither is the circuit board a perfect insulator and when you're looking at pico-amps (10−12),  a small current will be leaking away through it too.  Rather it's the 'effect' of the charge is passing through the gate insulator. The Wikipedia article is not very easy to follow. This Fairchild paper explains better (and with better diagrams)  by starting with the basic operation of  Junction Field Effect Transistors then moving on to the  MOSFET.   MOSFET Basics. Read it again in a months time  so that it sinks into your long term memory, then you'll also understand what is meant by a  VMOSFET and  DMOSFET when you see them mentioned. When designing and  building prototype circuits, all sort of unexpected things can happen due to stray currents and stray fields disturbing  adjacent components, so it is helpful to be aware of these things.--Aspro (talk) 09:42, 9 September 2010 (UTC)

Killing the pain
Endorphins are constantly referred to as "nature's painkillers." If they are the body's natural way of stopping pain, why do we take artificial substitutes instead of some kind of endorphin pill for our various aches? Or endorphin injections for people with chronic pain, etc. 71.104.106.143 (talk) 07:37, 6 September 2010 (UTC)
 * At a brief scan, I don't see the answer in the endorphin article, but my guess would be that they probably can't cross the blood-brain barrier. Maybe they would work if you injected them into the spinal column, but that seems extreme.... Trovatore (talk) 07:40, 6 September 2010 (UTC)
 * The article touches on this, noting that hypothalamic neurons release beta-endorphin directly into the brain; there is some question about whether or not endorphins circulating in the bloodstream are capable of crossing the blood-brain barrier in sufficient concentrations to be meaningful. Meanwhile, oral administration of peptides like beta-endorphin are plagued by technical difficulties. This article gives a good outline of the the major problems: digestion by gastric enzymes in the stomach and peptidases in the intestinal lumen; hydrolysis and denaturation by stomach acid.  (Be aware that the article is written by a company seeking to market products that purport to circumvent some of these problems, and take their assertions about how they have been 'solved' with a large grain of salt.)
 * In addition to the relative ease of delivery, the simpler synthesis, purification, and storage of synthetic small-molecule painkillers are not to be overlooked. The synthetics are generally much smaller molecules, and are apt to have a much longer shelf life (particularly when unrefrigerated).  TenOfAllTrades(talk) 15:16, 6 September 2010 (UTC)
 * There's also the issue that endorphins tend to be fast-acting (ie., to have quickly dissipating neuronal effects). Which is why chronic pain sufferers need pain management in the first place, of course.  (Chronic pain is a problem which our natural physiological responses don't deal with as well as modern medicine perhaps because it just wasn't too much of a problem in our evolutionary history (if you were hurt bad enough to have it, you'd probably just die before it got too bad?), whereas pain itself is very evolutionarily advantageous (subject to various trade-offs and exceptions, which endorphins are "designed" to deal with even more evolutionarily advantageously:).  Wikiscient  (talk) 17:18, 6 September 2010 (UTC)


 * I'd also be a bit worried about addiction issues. Endorphins aren't merely pain killers, they are euphorics; opiates, for instance, are close mimics of endorphins, and use of opiates can rapidly lead to psychological dependency.  Access to 'the real thing' might have some fairly nasty repercussions.  -- Ludwigs 2  17:53, 6 September 2010 (UTC)


 * It's a bit puzzling why our teeth have evolved to be capable of generating so much pain given that we haven't been able to do much about it until recently. It's pretty easy for a primate to crack a tooth and end up in a world of pain sometime later. Seems odd. This struck me as I was having a tooth pulled last week having lost patience with the tooth's not at all helpful approach to telling me that there was a problem.  Sean.hoyland  - talk 19:03, 6 September 2010 (UTC)
 * That might be because you have someone to pull the tooth. Otherwise... how are you going to be goaded into doing it yourself with your bare hands?  But more to the point, I suspect that our species first evolved in regions with [ very high flouride levels in the water]. Wnt (talk) 21:59, 6 September 2010 (UTC)

Thank you all for your efforts and thoughts. 71.104.106.143 (talk) 11:49, 8 September 2010 (UTC)

Could Gene Therapy help in the removal of scars?
I know I asked a similar question a while ago, only with the extracellular matrix with a cool video:

http://news.bbc.co.uk/2/hi/7354458.stm

but after reading this from http://curezone.com/forums/fm.asp?i=837983 :

"Have you ever wondered why scars persist on the skin even though the skin is by far the most regenerative organ that we have?

I have read some very interesting information lately on scarring. Contrary to popular belief on this site, scars are really not sites of incomplete healing or sites still in the process of healing. These areas of skin have healed. It's just that they have healed with scar tissue. Scar tissue is the glue that fixes the wounds.

A new generation of skin cells migrates from the basal cells (often called dermal stem cells) within the subcutaneous layer of tissue every 30-40 days. These cells will produce cells based upon the genetic information encoded within their cells that dictates the specific charachterics of each cell that slowly migrates to the epidermis (surface layer of skin). When tissue becomes scarred, the genetic information (DNA) within these basal cells actually becomes radically altered. In essence, the genetic formula for skin cells then becomes reprogrammed according to the scarred skin. The DNA of these basal cells now contains the information that instructs these cells to produce skin cells that are scarred. The scarring literally becomes locked within our DNA. It as if we were born with them.

This is why scars are perpetually on the skin even though the skin cells replace themselves every 20-40 days. Scars, as some would have you feel, are not areas of incomplete healing. These areas have healed and they have healed with scar tissue.

This is why scars are so difficult to change. You would have to figure out how to reprogram the DNA of these basal cells once again. Unfortunately, no one has been able to do this. Although scarring is easily programmed into the genetic information through the aquisition of a traumatic wound, it is impossible thus far to reprogram a lack of scarring.

Anybody who can figure out how will be the personal saviour of millions that suffer from scarring, especially facial scarring."

So after reading this, I am wondering if someone gets the reprogramming right, will it be possible to remove a scar for good?

I know the wikipedia scar article says it can't currently be done but it is does not address the applications in gene therapy and is quite old. I am also suggesting that a new article on scars be created so that new break thorughs in the medical world so that major breakthroughs like the one about the extracellular matrix can be incorporated into wikipedi and will be recognized and will give hope to millions upon millions of people who read the wikipedia article on scars and think that scar removal is impossible and give up hope.

Also, I was wondering if the article has a valid point on reprogramming scars

So thank you all very much. —Preceding unsigned comment added by 139.62.86.190 (talk • contribs)


 * I am very doubtful of the claim "When tissue becomes scarred, the genetic information (DNA) within these basal cells actually becomes radically altered". There is no mention of this in our scar article. I am sure that traumatic injury and subsequent inflammation triggers biochemical processes that lead to scarring, but I would like to see a reliable source for the claim that this actually modifies the DNA of the surrounding skin cells. Gandalf61 (talk) 09:36, 6 September 2010 (UTC)


 * They are probably talking about changes in gene expression profiles due to epigenetic changes in the cells around the wound (i.e. not altering the genetic information itself but changing the way in which different genetic programs are carried out). Basically, every cell type has a characteristic transcriptional profile that defines what that cell type does.  A deep skin injury would cause a variety of different responses, from the blood clotting cascade to degranulation of platelets and various immune cells, to local production of signaling molecules like transforming growth factor.  These conditions could set up the types of biochemical signaling pathways that would alter the gene expression of the skin cells and convert them from "normal replacement mode" to "repair mode".  That being said, I would expect that once the scar has been formed, the dermal cells would revert back to "normal replacement mode".
 * Finally, the scar article says:
 * "Scar tissue is composed of the same protein (collagen) as the tissue that it replaces, but instead of a random basketweave formation of the collagen fibers found in normal tissue, the collagen cross-links and forms a pronounced alignment in a single direction."
 * Basically what this means is that the repair process creates an imperfect solution that persists in the form of a scar. This isn't necessarily something that could be fixed by gene therapy, it requires remodeling of the extracellular proteins themselves. --- Medical geneticist (talk) 11:40, 6 September 2010 (UTC)

Gene therapy is unlikely to become useful in cosmetic surgery although stem cell therapy may find common ground between the two. Chemical peel may also be of interest. Why Other (talk) 22:36, 6 September 2010 (UTC)

Faith
Why is there such a division between those who believe in god and those who don't - what factors influence whether someone has faith? And is there any way people could do some big research project and prove the issue once and for all? TheFutureAwaits (talk) 12:52, 6 September 2010 (UTC)


 * Is there really "such a division" ? Althought there are clearly vocal extremists on both sides of the debate, I suspect the majority of people are more moderate and either don't feel the need to impose their own beliefs on others, or don't have a firm belief either way, or just plain don't care. Gandalf61 (talk) 13:02, 6 September 2010 (UTC)


 * Indeed. And what sort of a research project would be appropriate for proof of answers to such a question?  ("After six hours, the fleece was found to have retained 30ml/m3 of water as measured by psychrometer.")  Also, is this really appropriate for the Science desk?  It sounds like more of a Humanities problem. Marnanel (talk) 13:18, 6 September 2010 (UTC)


 * Perhaps you've heard of a discipline called Sociology? I hear they even use statistics these days... ;-) --Mr.98 (talk) 14:16, 6 September 2010 (UTC)


 * There have been some studies on religiosity and genetics; I don't have the references at hand and am not up to date as to whether they are seen as likely or crackpot. Just putting that out there as one of the proposed influences I have seen bandied around. There is a lot of work on Religiosity and intelligence, and religiosity and education, as well. --Mr.98 (talk) 14:16, 6 September 2010 (UTC)


 * We also have articles on faith and rationality and Relationship_between_religion_and_science for an overview. --- Medical geneticist (talk) 16:21, 6 September 2010 (UTC)


 * Do you mean "a big research project" to decide whether what some people have "faith" in (eg. "God") is really "real" or not, FutureAwaits? Because that's a big project that has been around for a long time: see eg. Existence of God.  But understand that "belief" becomes "knowledge" whenever faith does get settled that way, so there will always be room for faith as long as knowledge is incomplete.  Wikiscient  (talk) 19:11, 6 September 2010 (UTC)


 * Wasn't there also a large double blind trial on the power of prayer ? Didn't it show that hospital patients who knew that people were praying for them recovered more slowly from illness (possibly due to performance anxiety) ? I'm not sure whether it has been published yet. I recall it being mentioned in a Dawkins book.  Sean.hoyland  - talk 19:12, 6 September 2010 (UTC)


 * If the patients knew they were in the group being prayed for, the trial wasn't double blind. Unilynx (talk) 20:48, 6 September 2010 (UTC)
 * It would be if they knew someone may be praying for them, but didn't know for sure if they really were or they were getting the placebo (i.e. no prayer) 22:08, 6 September 2010 (UTC)


 * You're probably thinking of the STEP project. -- BenRG (talk) 21:19, 6 September 2010 (UTC)


 * It was double blind. Here it is. Yes, The STEP project. Thanks BenRG, I didn't know we had that article.  Sean.hoyland  - talk 02:08, 7 September 2010 (UTC)


 * It is misleading to try to determine the existence of God by the effectiveness of intercessionary prayer. Some might believe in the existence of God without prayer, or that mundane magic is not the purpose of prayer.  Perhaps the purpose of prayer is not to inform an omniscient God of one's woes and wants, but to allow the pray-er to address his faults and nobler desires within himself, or to feel the friendly companionship and love of the maker of the universe when all others fail, or to receive gentle guidance or divine inspiration, or to track through the words and logic of the ancient formulae to be able better to understand what is the right thing to do, or to strive toward Heaven regardless of the suffering on Earth.  Or, perhaps most likely, something I don't understand. ;) Wnt (talk) 21:36, 6 September 2010 (UTC)
 * Nobody claims that effectiveness of intercessionary prayer has any implications as to there being a God or not. The question is whether prayer accomplishes anything. It seems pretty plain that praying for other people does not seem to affect the outcome when it is being measured in a systematic fashion. One can interpret that theologically in a number of different ways. --Mr.98 (talk) 23:43, 6 September 2010 (UTC)
 * During the closing innings of the 1992 World Series the cameras focussed on the wife of the Atlanta Braves' owner, as she offered up a prayer. Possibly asking God to make sure the first-base coach didn't screw up the sign, I dunno. Franamax (talk) 23:54, 6 September 2010 (UTC)
 * Did those of you concerned with studies on the efficacy of prayer see yesterday's FA? (There's something to shake that kind of faith for you.) Sry, this really is getting to be more something for the Hum desk, huh?  Wikiscient  (talk) 03:57, 7 September 2010 (UTC)

Faith is defined in terms of doubt, and most faiths see the others as superstition. Given that any fact can be proven from a contradiction, the pattern is clear. Why Other (talk) 22:38, 6 September 2010 (UTC)


 * Bible science: Here's one of the few "scientific experiments" (in the form of a pick-up game of "celebrity smackdown") described in the Bible, btw: "Elijah's Challenge to Baal", which cites .  Wikiscient  (talk) 14:55, 7 September 2010 (UTC)
 * Isn't capitalizing "LORD" in that article against the Manual of Style? Why Other (talk) 06:16, 8 September 2010 (UTC)
 * Indeed. The talk page hints that "LORD" is used as the English equivalent to "YHVH", but I see no need to capitalize it in English, so I changed it. TomorrowTime (talk) 09:18, 8 September 2010 (UTC)
 * Please see Tetragrammaton about capitalization of "the ".
 * —Wavelength (talk) 20:22, 8 September 2010 (UTC)
 * No doubt that is appropriate in a theological discourse, but this is not a theological encyclopedia, and we are under no obligation to follow internal rules of one of the religions. I see it as the flipside of Wikipedia not being censored. TomorrowTime (talk) 20:32, 8 September 2010 (UTC)
 * At http://www.multilingualbible.com/psalms/110-1.htm (NAB), "the " (Jehovah, the Father) is distinguished from "my Lord" (Jesus, the Son).
 * —Wavelength (talk) 21:50, 8 September 2010 (UTC)

"Division" is a personal choice. Every religion, philosophy, belief system can be a tool to join (and reconcile) or to divide. It is merely the tool. The question is, what is the intent of the individual wielding the tool? As with the proposed Qur'an burning in Gainesville, Florida, one must not ascribe to the tool the goals of the one who has wielded it. Of course, the proposed burning itself (per responses to "Would Jesus approve?" stating "Yes!") is also not reflective of the teachings of Bible (tool) but of the goals of the Qur'an burner. P ЄTЄRS J V ЄСRUМВА  ►TALK 15:31, 8 September 2010 (UTC)

P.S. There is no dearth of xenophobic individuals on the planet. I'm sure Jones's congregation will grow from its current paltry 50 as a result of this (IMHO) inspired publicity stunt. P ЄTЄRS J V ЄСRUМВА  ►TALK 15:44, 8 September 2010 (UTC)


 * I'm not sure that any of us have really addressed the questioner's question "what factors influence whether someone has faith?" I'm not going to either but I will provide links to neurotheology and Michael Persinger's "God helmet" as they might be of interest to the questioner.  Sean.hoyland  - talk 15:50, 8 September 2010 (UTC)


 * Studies have shown that where individuals have explored faiths other than their family's ("original") faith, they more often than not wind up where they started. Faith has always been, and will be, a comfort in the face of the unknown. Whether food or faith (organized religion), our favorite is most likely what we grew up with, even if that relationship is somewhat ambivalent. "Finding" or "losing" religion, on the other hand, is usually associated with the resolution of a personal crisis—needing faith to face a crisis, or believing faith or God "deserted" them when needed most. Lastly, of course, there's simply not caring, which is different from agnostic. P ЄTЄRS J V ЄСRUМВА  ►TALK 20:06, 8 September 2010 (UTC)


 * There are a number of excellent books on the causes and maintenance of religion. It is only natural that there is variation in humans on such a problem. Imagine Reason (talk) 22:01, 10 September 2010 (UTC)

Plasma-powered cannon
I was looking at this article, and found it fascinating. Would the plasma created leave behind any chemical residue that would have to be cleaned as is the case with traditional propellant based firearms? ScienceApe (talk) 14:15, 6 September 2010 (UTC)
 * From the article, it looked like it "plasmized" the air, so only air would be a residue. Maybe some oxidation of the bullet would happen, but not much. --Chemicalinterest (talk) 21:09, 6 September 2010 (UTC)
 * I thought it said it "plasmized" a small amount of non-combustible propellant? ScienceApe (talk) 22:56, 6 September 2010 (UTC)
 * I'd say that you will definitely have some vapourized electrode left behind, for sure. You will also have chemical alterations in most everything the plasma touches or gets close to, after all it cuts steel. Franamax (talk) 23:33, 6 September 2010 (UTC)

Cost of building road tunnels
In an ideal world, cars would travel in underground tunnels, leaving the noise- and pollution-free surface to humans. In reality, it is usually too expensive.

What makes up the greatest costs in building shallow road tunnels? Is it labour, or energy for example? Or the cost of materials, or the cost of disposing of the waste? Thanks 92.15.11.248 (talk) 16:25, 6 September 2010 (UTC)


 * dig —Preceding unsigned comment added by 77.126.131.222 (talk) 17:12, 6 September 2010 (UTC)
 * What is that supposed to mean? 92.15.19.57 (talk) 19:30, 6 September 2010 (UTC)
 * see the Big Dig article, which discusses the costs and problems encountered when they did this in Boston. -- Ludwigs 2  17:55, 6 September 2010 (UTC)
 * It gives overall figures, but I cannot see any answer to my questions. 92.15.19.57 (talk) 19:30, 6 September 2010 (UTC)


 * sorry, I thought a breakdown would be in there. you might do some googling and improve that article, because I know this has been discussed extensively in newspapers (it was a controversial project).  My guess it would be mostly materials and equipment - tunnel boring machines, for instance, are exceedingly expensive to rent (if I remember right, it can get to 4 or 5 figure bills per day) - so project slowdowns can cause rapidly mounting overruns.  Waste disposal would not be overly expensive since the material is non-toxic earth - I think Massachusetts used it for land fill to expand one of the bay islands.  -- Ludwigs 2  19:48, 6 September 2010 (UTC)


 * As a side note, I disagree about tunnels being ideal. A lot of the enjoyment of driving is the scenery. Also, tunnels don't magically get rid of pollution - it just gets out, one way or another, into the open air. Clarityfiend (talk) 20:22, 6 September 2010 (UTC)
 * That is a selfish car-centric view. 92.28.248.94 (talk) 00:05, 7 September 2010 (UTC)
 * Shared by the pedestrians. How many would prefere ungerground to sunshine? East of Borschov 11:54, 7 September 2010 (UTC)
 * The pedestrians would be on the surface, cars underground. And in answer to your next question, you would have underground car parks and lifts. And your next question after that, those electric scooter things for the infirm. Part of the charm of Paris must be due to the dense Paris Métro removing much of the traffic. 92.29.115.74 (talk) 13:03, 7 September 2010 (UTC)
 * And depending on the material you will be digging through, the cost of repairing all the damage caused above ground, as they found out with the North/South Line (Amsterdam metro). As far as the pollution is concerned, for the 3 billion being spent on that tunnel they surely could build a few 30 meter high pipes to at least get the pollution out of the city. Unilynx (talk) 20:57, 6 September 2010 (UTC)


 * I don't know the answer, so I'll add a question: How about at least roofing/walling limited access roads with solar collectors, to achieve the same as above (and put an end to snowplowing), and to provide that "area the size of Massachusetts" that solar naysayers are always asking about? Wnt (talk) 21:20, 6 September 2010 (UTC)
 * This would cause a public outcry because it would raise the "price of gasoline" (as end-users would see it, at least). Most road construction is financed by tax on gasoline  - so paying for a "solar-powered road roof" would ironically mean more expensive gas!  Massively restructuring the finances for a major civic utility like the national highway system would require a huge amount of politicking and bureaucracy - and at least in the United States, politicians are too busy running for election to worry about such things.  Nimur (talk) 02:04, 7 September 2010 (UTC)

The answer is "poor planning" -- people make assumptions that the cost of construction for any set of infrastructure improvements is always above a certain amount, and they estimate the benefits as below that cost. The details are different for any circumstance, but there are plenty of reasons to perform countless infrastructure improvements which are not done because of negligent and ineffective government officials. You may enjoy the "Infrastructurist" blog: http://www.infrastructurist.com/ Why Other (talk) 22:45, 6 September 2010 (UTC)
 * Safety might also be a factor, we have a tunnel in the city where I live and there have been a few high profile accidents that have happened in there. I'm not saying it's less safe in a tunnel, but certainly if an accident happens then it is more difficult to clear the accident and evacuate victims, especially if there is a spill or fire or something. For that reason dangerous loads are actually not permitted in the tunnel so things like fuel and gas trucks can't use them. Vespine (talk) 23:41, 6 September 2010 (UTC)


 * I can't imagine this being 'ideal' except in large, dense cities, like New York or Boston, (Where, frankly, the ideal would be to eliminate private cars somehow.)
 * As noted above tunnels don't make the pollution go away, at best they move it out of the city. (Where? Over the ocean perhaps?) Also, tunnels require a good amount of powered ventilation, lighting, cel-phone repeaters, etc. Again, all acceptable in a big city that is desperate for somewhere to put all the cars, but in the suburbs I'd hate to think that my roads were consuming electricity 24/7. (And therefore producing greenhouse gases!)
 * Right now GPS doesn't work underground, we'd have to deal with that somehow if all the roads went underground. (This might actually be a savings if we didn't need to keep the existing GPS network, which we do, so it actually represents more energy use for something that we've already got above ground.)
 * There's safety issues of course. Maintenance costs go through the roof. Want to add a new lane to accommodate growing traffic? You're going to need a whole new tunnel!
 * Also, what goes above ground where the roads used to be? Will their be bicycle paths? Walking paths? That all sounds very pleasant, but right now in the suburbs we can hardly get them to build sidewalks. I don't mind riding my bicycle on the street, but I'm sure not going to ride through a tunnel.
 * I don't know what the "ideal" solution for transit is, but it sure isn't "Take what we've got now and put it underground so we don't have to look at it.". That doesn't fix anything, it just sweeps it under a phenominally expensive rug. APL (talk) 03:25, 7 September 2010 (UTC)
 * In the UK dedicated cycle-paths and pedestrian-paths, which often follow different routes from car roads, have been commonplace features of new developments for a long time, and I think in much of Europe too. 92.15.12.116 (talk) 13:22, 7 September 2010 (UTC)
 * Yes, even clean traffic is a form of pollution which prevents people from getting walking exercise in developed countries such that obesity may soon overtake tobacco as the number one preventable cause of death. Why Other (talk) 06:26, 8 September 2010 (UTC)

There are a number of existing technologies which suggest that underground transport (which really only applies to cities or towns) is nascent and could become a reality if the cost of building shallow tunnels could be reduced a lot. Electricity, gas, water and sewage already usually go underground. Various existing or past examples of underground transport include the London Underground. The Chicago Tunnel Company had an underground system for delivering coal and so on to buildings. The Prague pneumatic post was one of several pneumatic tube systems which would automatically deliver packages to the right address. So the futuristic ideal would be each home or building having a basement portal to electric driverless tunnel-taxis fuelled by renewable energy, leaving the surface leafy and bucolic. 92.15.12.116 (talk) 13:37, 7 September 2010 (UTC)
 * My futuristic ideal is Star Trek style transporters, metaphysical considerations be damned! Googlemeister (talk) 14:12, 7 September 2010 (UTC)

A cheaper alternative may be just to lay the tunnels and utilities on the surace and create a fake natural-looking surface above them. It has the side-effect of creating lots of underground space. This has been done to a certain extent at the Barbican Estate, although there the surface is mostly paved rather than grassed or wooded. 92.15.20.52 (talk) 16:49, 8 September 2010 (UTC)

Some curious experiments
"Take a small box made of stiff parchment, pour water in it, and try to boil an egg in it. You will find, to your surprise, that the water will start boiling but the paper will not burn. In a similar vein, take a thick nail or an iron (or better copper) rod and tightly curl screw-wise a narrow strip of paper around it. Then apply a flame. The flame will lick the paper and even smoke it; but it will start burning only when the rod glows red-hot. Explain."

This was, incidentally, a question posed on the first assignment for my Quantum Mechanics class...yeah. Well anyways, I'm not sure what the solution is. The only thing I can think of is that both the water in the first experiment and the screw in the second will "steal" the energy being applied to the paper, but this doesn't seem like a very convincing argument. 74.15.136.172 (talk) 23:46, 6 September 2010 (UTC)
 * For the water/paper example, that's certainly the case. The water and the paper will be at about the same temperature (because their in close contact, and heat transfer will be very efficient).  But water never gets warmer than 100 C (212 F) (under normal conditions).  Paper doesn't burn until it is much warmer (451 F, if Ray Bradbury is to be believed).  The paper cannot reach that temperature until all of the water is gone.  It's easy to try it; fill up a paper bathroom cup and put it on the grill.  The top, not in contact with the water, will burn, but the rest of it won't, and the water will boil.  I suspect that something similar is happening with the nail, though I've never done that. Buddy431 (talk) 00:01, 7 September 2010 (UTC)
 * The same principle can be used to boil water in a plastic bottle over a fire if you have no other utensils, like if you get lost in the bush or something. Vespine (talk) 01:52, 7 September 2010 (UTC)
 * (Although doing this with a plastic bottle isn't the sort of thing I'd want to do on a regular basis. Food-safe for room temperature is not the same as food-safe for boiling, and I have no idea what temperatures those plastic bottles are rated for.) APL (talk) 03:07, 7 September 2010 (UTC)
 * See also plasticizer, e.g. bisphenol A. Where there's a plastic there's a plasticizer, and more often than not, you have no desire to eat it. Wnt (talk) 04:04, 7 September 2010 (UTC)
 * Boiling an egg in a paper cup placed in an open fire works surprisingly well. There's no special conditions you have to set up. You can place it right on the burning wood in the middle of the fire if it's level enough. It's a good trick. I felt like a magician doing it. (ProTip : Have a plan for getting the cup back out of the fire when your egg is done.) APL (talk) 03:07, 7 September 2010 (UTC)
 * Sorry yes I wasn't advocating boiling water in plastic bottles for fun, but if you are stranded in the wild in a desperate situation and your choice is between dying of dehydration, drinking possibly contaminated water or boiling the water and possibly ingesting some plasticizer, I don't know which is worse. Vespine (talk) 04:54, 7 September 2010 (UTC)
 * It's probably the difference between dying of dyssentary or cholera on the one hand, and increasing your chance of getting cancer by 0.01% on the other hand... -- Jayron  32  05:04, 7 September 2010 (UTC)
 * Yea, I just I wouldn't do it regularly as a parlor trick. (You know, at your water-boiling parties.) On the rare occasion when I'm thirsty and the only source of safe water is water boiled in a coke bottle, I'd give it a try without hesitation.  Thinking about it a little more, I'm not convinced that the Coke bottle would hold it's shape at water-boiling temperatures. (Now I'm going to have to try this next time I'm near a camp fire.) APL (talk) 05:50, 7 September 2010 (UTC)
 * I've seen it done and you are right, it might have even been on youtube, i can't search for it at the moment. It doesn't deform completely but the base rounds off somewhat and the narrow ridges pretty much disappear. Vespine (talk) 06:23, 7 September 2010 (UTC)

Thanks for the replies, but does anyone know what happens in the case of the screw? 74.15.136.172 (talk) 11:12, 7 September 2010 (UTC)
 * Better to use a nail or a metal bar than a screw, so that you have good thermal contact between the paper and the metal. The principle is similar, but not exactly the same. With the water, you keep adding heat but the temperature doesn't rise because the energy goes in transforming liquid water into gas. In the case of the metal bar, the temperature does rise, but only quite slowly because metals are good conductors of heat – especially copper, and that's a clue in the question. So you apply a small flame to a biggish chunk of metal, and the flame has to heat up the whole chunk of metal at the same time, because the heat is conducted away from the contact point so effectively. Physchim62 (talk) 11:31, 7 September 2010 (UTC)
 * I'll bet that this is harder to make work in practice. It would only take the tiniest of air-gaps between the metal and the paper to allow the paper to burn. (Water will automatically conform to the paper.)APL (talk) 18:19, 7 September 2010 (UTC)

Thanks everyone! 74.15.136.172 (talk) 22:06, 7 September 2010 (UTC)
 * Back in 1842, Michael Faraday told how to make a variety of chemical lab apparatus out of paper, in his "Chemical manipulation: being instructions to students in chemistry.." pages 578-581. Edison (talk) 18:01, 8 September 2010 (UTC)
 * I do not see that in the page you link, only standard stuff about using paper filters and using paper cones to cover crystalising solutions. Did you mean to link something else? 86.164.78.91 (talk) 22:27, 8 September 2010 (UTC)