When considering radiation heat transfer through a solid: Absorbion [sp] + Reflection + Transmission = 1. Pretty simple going one way while getting into the greenhouse so following me so far?
Man, nobody disputes that. I UNDERSTAND that. But it does NOT explain how a greenhouse works. While it's true, it's NOT THE PRIMARY MECHANISM of a greenhouse.
Thus with less than perfect transmission some heat does not radiate to the outside and the greenhouse gets hotter than something else that is the same apart from not being under glass
NO. That is one possible explanation for how a greenhouse works, but NOT the correct one.
Look, there are SEVERAL mechanisms of heat loss (convection, conduction, radiation) happening SIMULTANEOUSLY. Furthermore, a greenhouse does SEVERAL things simultaneously. A greenhouse allows light through, which heats the ground, which heats the adjacent air, but the glass prevents hot air from floating up into the broader atmosphere and pulling cold air downwards (in other words, a greenhouse prevents convection over a wide area). ALSO, at the same time, a greenhouse allows visible light through the glass, and that visible light heats the ground, and the ground emits IR radiation, but the glass is somewhat opaque to IR radiation, so the glass re-radiates IR downward, and heat doesn't escape. ALSO, a greenhouse allows heat to enter from the outside, and the heat "tries to get out again" (as you said) but some of it is reflected back inward. SEVERAL of these things are happening AT THE SAME TIME. A greenhouse prevents SEVERAL different mechanisms of heat loss, all at once. The question is: WHICH ONE is primarily responsible for the heating effect?
With me so far?
Don't just REPEAT one of these effects. Doing so answers absolutely nothing! The question is: WHICH EFFECT is most important. You cannot answer which effect is most important, by just repeating ONE of the effects. You must do an EXPERIMENT to find out which is the most important.
The question of which effect is most important, has been answered by experiment and theory. The PRIMARY mechanism of greenhouse heating is the PREVENTION OF CONVECTION. The OTHER effects listed (reflection of heat, etc), while they are occurring, are FAIRLY NEGLIGIBLE. I UNDERSTAND the other effects, it's not that I don't get what you're saying. But those effects are NEGLIGIBLE in explaining why greenhouses are hotter.
This explanation is what ALL the sources clearly say. This explanation can be demonstrated by easy experiments. It's what I've been saying all along, apparently unsuccessfully. Again, from wikipedia: "the greenhouse re-radiate some of their thermal energy in the infra-red, to which glass is partly opaque, so some of this energy is also trapped inside the glasshouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse IS CONVECTION [my emphasis]."
When you respond:
Absorbion + Reflection + Transmission = 1, thus with less than perfect transmission some heat does not radiate
...you ARE NOT contradicting what I said, or what any of the sources say. You are just repeating a negligible factor!
Look - it works the same way in as fucking vaccum so convection DOES NOT MATTER
NO.. ONCE AGAIN, a greenhouse works by preventing convection from the INSIDE to the OUTSIDE of the greenhouse. As a result, a vacuum INSIDE the greenhouse is totally irrelevant because it HAS NO EFFECT on whether convection is happening from the inside to the outside. You would need a vacuum over the entire surrounding atmosphere to tell if convection (with the WIDER ATMOSPHERE) is the cause.
Because of less than perfect transmission the heat doesn't all get in and not all of it that can get in can get out so things get hotter than outside - IS THAT SIMPLE ENOUGH FOR YOU.
That explanation is simple but it's WRONG. Once again, from wikipedia: "Thus, the primary heating mechanism of a greenhouse is convection." That's totally obvious and unambiguous!
The wikipedia article specifically says that the explanation you offer is INCORRECT, as does the original linked article.
You haven't responded to ANYTHING in my posts, which is weak even as a troll!
please stop wasting your time and mine just because you wish to attempt to spread your ignorance to somebody that has know about this for decades.
You obviously haven't known about this for decades, because you don't know about it now. Instead, you had an elementary misconception for decades.
You cling to your misconception, because your fragile ego prevents you from admitting your error, despite multiple sources which tell you over and over again that you're wrong.
Nobody was arguing that convection inside the greenhouse was the important factor
However here is your comment that triggered my response in the first place:
Nope, a greenhouse works by preventing convection
You truncated the first quotation, and misread the second.
The quotations should have been:
Nobody was arguing that convection inside the greenhouse was the important factor. The claim was that a greenhouse prevents convection with the wider atmosphere.....Nope, a greenhouse works by preventing convection [with the wider atmoshpere]
...but those are compatible.
The original claim was that greenhouses work by preventing convection with the wider atmosphere. Maybe I should have spelled that out more; maybe that was the source of confusion.
Of course there's not some barrier within the greenhouse preventing convection inside. That was never the claim. The glass prevents convection from the inside of the greenhouse to the outside of it.
There's no point trying to look for extra complication (adding an extra mode of heat transfer
There's no extra mode of heat transfer being added here. The original article was talking about convection with the wider atmosphere, and that's what my original post was about. The entire thread has always been about that mode of heat transfer.
but you can save youself a lot of time by sketching up a simple line model with arrows showing which way inputs and outputs go to get better understanding of how it works. There's no point trying to look for extra complication (adding an extra mode of heat transfer just for the fun of it), confusion, altering from a steady state and incorrect assumptions such as in your final paragraph.
No. You can't determine how a greenhouse works from sketching a steady state diagram of energy flows. The steady state diagram is compatible with multiple explanations. You must determine what has changed by the addition of a greenhouse.
Opening the window as in your example of course changes the system.
Of course opening the window changes the system. Every experiment changes the system, including your vacuum experiment--but the vacuum experiment doesn't yield an answer here since the result would be the same regardless of how a greenhouse works. I wanted to replace your vacuum experiment with one which determines what the correct answer is.
You've obviously gone to a lot of effort, written a lot
Don't worry; I write really fast, and it actually takes me only 5 minutes or so to compose a reply. The reason for the long delay between my responses was because I was on the road and can't type fast on my droid, so I waited.
The reason I posted the initial comment is because you can do an accurate thermal model of a greenhouse without considering convection inside at all. Heat loss and gain via radiation is the important factor and external convection from the outside skin and conduction into the ground are lesser factors. Convection inside? Who cares, it doesn't matter.
Ok, but this isn't important. Nobody was arguing that convection inside the greenhouse was the important factor. The claim was that a greenhouse prevents convection with the wider atmosphere.
It doesn't matter if the greenhouse loses all its energy as IR radiation. The question is whether a non-greenhouse area of ground loses all its energy as IR radiation. The question is: what is changed by the addition of a greenhouse. If a greenhouse loses all its energy as IR radiation, then this could mean that convection over a wide area was prevented, and IR radiation is the only remaining route of energy loss.
Maybe you could call that a "house" effect but it really has nothing to do with the way greenhouses are warmer than normal buildings. Replace air in the greenhouse with a vacuum and you'd still get the same temperature for all the objects inside because, as the article linked above and everywhere else says, heat transfer by radiation is what is happening.
This is directly and clearly contradicted by all the sources on this issue. Furthermore, what you say is clearly not what the linked article says, which clearly states that greenhouses work by preventing convection over a wide area. From the article: "In a greenhouse, this mixing [convection] is confined to the layer of air trapped under the roof, so there is a much smaller mass to be heated. Essentially, the large kettle full of water has been replaced by one with half an inch of water on its bottom, and as a result the water will warm up much faster." I just don't see how there is any other interpretation.
And something similar is said by all the other sources I've read on this topic. They are very clear and straightforward in claiming that greenhouses work by preventing convection over a wide area. They also leave no room for interpretation. They are perfectly clear about this point. For example, here is a sentence from the first paragraph on the wikipedia article about greenhouses: "Thus, the primary heating mechanism of a greenhouse is convection." I just don't see how there is any alternative interpretation of that.
Saying that "it [preventing convection over a wide area] really has nothing to do with the way greenhouses are warmer than normal buildings" appears to directly contradict these sources.
Replace air in the greenhouse with a vacuum and you'd still get the same temperature for all the objects inside because, as the article linked above and everywhere else says, heat transfer by radiation is what is happening.
The question was: why is a greenhouse hotter than a non-greenhouse, which can be either: 1) it prevents convection over a wide area; or 2) the glass absorbs and re-emits IR radiation and heat downwards back into the greenhouse. Replacing air in the greenhouse with a vacuum, would offer no way of deciding between these two hypotheses, because the vacuum-greenhouse experiment is compatible with both hypotheses. A vacuum-greenhouse would do both; it would re-emit IR radiation and also prevent convection.
The way to decide between these two hypotheses is to have a greenhouse that has a small slit near the bottom and another on the top, which you can open and close using vents. If greenhouses work by absorbing and re-emitting IR radiation, then opening the vents should make very little difference to the heat inside. If, on the other hand, a greenhouse works by preventing convection with the wider atmosphere, then opening the vents should make a huge difference. In fact, it makes a huge difference, as you can see by cracking your windows on your car during a hot day. This is because a greenhouse works by preventing convection with the wider atmosphere, as is claimed by the linked article and the other sources I have.
Name dropping or calling to authority isn't going to help elevate your bullshit
I wasn't arguing from authority. I was referring you to source material written by someone who has expertise in this area, and who knows more about it than you do.
You could also have typed "greenhouse" into google and found many other cogent explanations of how greenhouses work; but I suppose those also are "calls to authority."
With regard to "name dropping." You should look up that term, and think about what it means, before you use it. There was no name dropping in my post.
bullshit which is yours by the way and not from the article which I've just read and does not say what you pretend it does.
Really? The article doesn't support what I'm saying? From the article:
The increase in temperature is conducted to the air next to the earth; that air then warms and expands, thus becoming less dense than the air higher up. The lighter air rises, allowing cooler and denser air to take its place at the surface and absorb more heat from the warmed ground...
Above open ground on a sunny day in summer, the heated layer of air may easily be a mile or more deep, and since the warming is spread over such a large mass, the temperature rise is diluted by the sheer amount of stuff that must be heated... In a greenhouse, this mixing is confined to the layer of air trapped under the roof, so there is a much smaller mass to be heated.
And from my post:
A greenhouse works by preventing convection over a wide area. Although convection still happens within a greenhouse, the thermal mass of air to be heated is far smaller, since the greenhouse prevents convection over a much wider area.
Do you really think that the article doesn't support what I wrote? It's perfectly clear. Read it again, more carefully.
You also claim that I'm taking the analogy too far. You wrote:
Also you've taken the analogy way too far to the point where it is completely irrelevant. The earth doesn't have a fucking glass ceiling and is not floating in a vast dense interplanetary atmosphere. Only the radiation component of heat transfer matters in this model so your rambling about convection
You didn't understand the conversation to which you're contributing.
I wasn't the one drawing an analogy between the earth and a greenhouse. That was the other side.
Again: read and understand the material before responding.
that you wish to mislead people or that you have been taken as a sucker and are parroting somebody else's bullshit. Why do you think this is important enough to lie about? Why do you think we are all so poorly educated that we cannot see through the lie? What is your game here?
The only "game" here, is that you ran your mouth off, without reading or thinking first. Then you got caught in an elementary mistake about how greenhouses work. But you weren't big enough to admit it, so you decided to continue running your mouth off. Then you made some more silly mistakes, and you incorrectly attributed the greenhouse analogy to me.
I'm not going to continue this silly conversation with you any more. This could go around in circles for a long time. I could point out any number of sources which explain how a greenhouse works, but you'll just say they're "appeals to authority," then spout more silly mistakes or try to change the topic. There's no way I can force you to read and understand the material.
You may also be upset about my harsh tone. However, you set the tone here. This was a dispassionate and adult conversation until you arrived.
There was a geart research study done on this in the early 1900's. If you build two identical small greenhouses, one from glass (which stops infrared) and one from salt crystal (which passes infrared), the glass one will be cooler. As it turns out, there's more IR coming in than leaving a greenouse, and as Feynman says, one experiment trumps 1000 opinions.
Nope. Experiments were done in which two greenhouses were built, one from a material which blocks IR radiation and another from a material that doesn't, and both heated up at approximately the same rate. This is because a greenhouse works by preventing convection over a wide area. This experiment has been done many times and has always yielded the same result.
This issue is explained clearly in the linked article, by a professor of physics.
Your beliefs in this area seem to be guided by religious faith, rather than even the most basic of research. Maybe you should fix that,
You're reading into my motives here. You're not responding to what I actually wrote! There was no reference to religious faith in my post.
Don't think about what I'm trying to accomplish, or what motivates me. Focus on the content of what I wrote!
I should probably elaborate (although it's not really important to the point here) that some glass does indeed block IR radiation. Some glass has coatings or materials added to block IR radiation. Nevertheless that's not how a greenhouse works.
Nope, you misunderstood what you read completely, and you didn't bother to read the posted article.
Thus the analogy only applies for heat loss by radiation from a greenhouse and making noises about convection shows either ignorance of a very simple model or that some confidence trick is being played or parroted without thought.
Nope, it shows you don't understand what you're reading. Please READ AND UNDERSTAND THE SENTENCE to which you're responding.
A greenhouse works by preventing convection over a wide area. Although convection still happens within a greenhouse, the thermal mass of air to be heated is far smaller, since the greenhouse prevents convection over a much wider area. As a result the interior of a greenhouse heats up much more quickly than an open area. As a result, a greenhouse works by preventing convection. Glass is not opaque to IR radiation.
This issue is clearly explained in the linked article, by a professor of physics. You apparently were unable to read more than the first paragraph of that article, and you badly misunderstood the sentence you read in my post.
If you really mean what you have written literally then it's yet another sign of a failure of science education... Thus the analogy only applies for heat loss by radiation from a greenhouse and making noises about convection shows either ignorance of a very simple model
You were the one showing ignorance of a very simple model--a model which could have been understood if you had bothered to read the article, beyond the first paragraph. You should have been able to read the entire article since it's about a page long.
Indeed, this is a failure of education. You simply cannot read, or you don't bother. You didn't read (or understand) the 1-page article from a professor of physics, and you didn't understand the sole sentence in my post to which you were responding.
In fact, even the genre's title is misleading. The Globe is not Warming. Yes, there is probably Climate Change, which may or may not be human activity driven, but the idea that the globe is warming and the net result is more deserts between the tropics (which seems to be the layman's view) is really rather preposterous and totally unjustifiable by facts.
The globe is warming on average. This point is virtually undisputed, and is verified by temperature readings all over the globe and by satellite IR readings.
Furthermore, deserts are expanding; this point is also undisputed.
The reason they're changing the name from "global warming" to "climate change" is because the globe is only warming on average. Many places will get cooler as a result of climate change, because of changing ocean currents. Lots of people misunderstood this point. People have said "well the winters are getting colder here--so much for global warming!" which means they misunderstood the notion of average global temperatures increasing.
Changing the name from "global warming" to "climate change" isn't an attempt to mislead people; it's an attempt to un-confuse them.
Nope, a greenhouse works by preventing convection. The article you linked says this, and not what you claimed.
You may not have read the entire article you linked. It starts off by saying: "If you've ever heard an explanation of how a greenhouse works, it was most likely based on the differing transparency of glass to solar and thermal infrared radiation", but then the article goes on to show how that explanation is incorrect.
I definitely agree with you about C02 and global warming. I believe that global warming is occurring, and is caused by humans. However I must nitpick something you said.
You claimed that C02 traps heat, that we can test this, and that we emit lots of C02. Therefore, we are causing global warming.
However, even the global warming deniers usually admit this much. What they deny is the feedback effect, whereby a slight warming of the earth's atmosphere causes changes to Albedo, cloud cover, etc, which further enhances the warming. That's the contentious point.
The C02 by itself would raise Earth's temperature by only 1 degree celcius or so. It's the feedback which is really important, and which will raise the temperature by another 4 degrees or so.
The feedback effect depends on things like: how much ice will be melted, how much that melting will effect the reflectivity of the earth (albedo), how much methane will be released from melting permafrost, etc. These things are based upon calculations and sometimes models, and also upon paleoclimatology evidence which suggests that small changes in C02 caused disproportionately large changes in temperature. Unfortunately it's not possible to test feedback effects in a simple way with home experiments.
I have a BSCS and over 1.2 million lines of code and I can't get a job easy. 4% percent is a lie. It is more like 25%.
You seriously think that unemployment among programmers is "more like 25%?" Are you serious? Do you live in your own little world? I don't know a single programmer who is involuntarily unemployed at present.
You are a troll so you should be modded down.
Then you should be modded stupid. You think your own failure to get a job signifies something about the broader market for programmers.
I see I've been modded down to "troll" by pointing out something which nobody could seriously dispute.
Such as how little they are willing to work for. Just recently I read a comment here on slashdot from some developer who said his whole team had been working 12-16 hour days for a year and a half with no extra pay...
That's just ridiculous and silly.
It's extremely easy to find a job as a programmer right now which pays highish wages relative to other jobs, and which doesn't require working 12-16 hour days. Although there is significant unemployment right now, that unemployment is almost entirely among the working class, and among people who used to be employed in construction etc, and among millenials. The unemployment rate among experienced programmers is 4% at present, meaning unemployment in that sector is almost entirely frictional. At my company, for example, we're trying to find qualified people to hire, but it's virtually impossible. In other words, the labor market for programmers is as tight as it's ever been, with the possible exception of the 1999-2000 timeframe.
Whoever is working 12-16 hour days for no additional money, for a year and a half, has made a silly choice, and has done himself harm for no reason whatsoever. He has many other easy alternatives, which he chose not to investigate or pursue.
Of course, there are many people in this economy who lack skills or experience, and who are seriously suffering. But here we're getting complaints from programmers who have careers in a field with 4% unemployment.
One needs only to type "software engineer pay" into google and come up with links like this one which clearly indicate that someone with a Bachelor's degree makes $60k-$120k per year (not including benefits), Or I could type "unemployment sector" and find that the unemployment rate for programmers is half the national average and that: "With an unemployment rate of under 4% in the tech sector, there’s a shortage of qualified technology professionals, TechFlash reports." Or I could type into google a query about how many hours most programmers work, and find from the Bureau of Labor Statistics that: "Most software engineers and programmers work 40 hours a week, but about 15 percent of software engineers and 11 percent of programmers worked more than 50 hours a week in 2008" which obviously means that working 12-16 hour days is rare. All this took about 60 seconds of research, but perhaps the people working 12-16 hour days never bothered to type these things into google?
Part of living in a capitalist economy involves looking at the options available to you and selecting the best one given your circumstances. I know there is always some rare person who says something like: "I paid $45,000 for a $25,000 car, because I didn't even bother to walk across the street to some other dealership to look," but it's rare and signifies nothing other than that some lone person got ripped off.
The odd thing is that there's constant complaining on slashdot among people, who are essentially highly privileged or fortunate workers. Programmers make $60-$120k for a Bachelor's degree and work 40 hours per week (which apparently is average, according to the BLS) with an unemployment rate of 4%. Clearly programmers are in the top 1% of workers worldwide, by a very comfortable margin, and are within the top 10% even among the rich countries. Nevertheless, they constantly insist on slashdot that they deserve much more than this and that they're the modern equivalent of slaves, that laws should be passed favoring them even more and that they should form unions etc.
I realize this will be modded down to "troll". Of course, there are a few modders here (not most of them, of course) who think that anything which challenges any idea they have in their heads is a troll. Ohwell...
If you think about it, you are better off in the International Union of Elevator Constructors or the International Brotherhood Of Electrical Workers, than being a rank and file coder.
You don't seriously think this. Working class employees are treated far worse, have fewer options, make far less money, get fewer benefits, are less secure, and have less rewarding work than almost any white-collar employees. Everyone know this. Why would people spend $100k on college education, and lose years of earnings, with no promise of a career, if everyone wanted a blue-collar job. Unions didn't work out for the employees of GM, or for that matter, almost any other unionized industry. What's in demand are skills and no level of organization will ever compensate for the lack of them.
If you run a company without an accountant, the only bad thing that will happen is the tax man will get angry.
I don't think you really believe this. Accounting is probably more important than software (this is coming from a programmer).
If you run a company without an accountant
Try running a company with more than 3-4 people without some kind of accounting. And don't say "I worked for company x with 10 employees and they had no accountant" because they did have an accountant, just somebody who had other roles as well.
Even with a company that has only 3-4 people, somebody is doing accounting, if only in their heads. They're doing mental accounting, which is very simple, but it's still accounting.
We couldn't even collect taxes, or have a civilization, or pay employees without accounting. We could build nothing that required more than a few people, or required any kind of coordinated effort. Accounting made civilization possible. Accounting was almost certainly the reason people invented writing in the first place (numerals came first).
If you run a company without an accountant, the only bad thing that will happen is the tax man will get angry... If you run a company without software, you have no company.
No, no, no. You can easily run a company without software, as all companies were run without software until quite recently. But you cannot run a company without some kind of accountant. Even the idea of "a company" requires wages at different levels, records of payments, retained earnings, planning, etc.
Such as how little they are willing to work for. Just recently I read a comment here on slashdot from some developer who said his whole team had been working 12-16 hour days for a year and a half with no extra pay...
Then they're all just being dumb. Why would they do something like that. Right now they could easily find far better jobs that require working only 45 hours per week or less. I get calls from recruiters all the time. Don't those guys get similar calls? Why do they remain in such a job when there are so many obvious and easy alternatives? Are they just dumb or something?
Because it would "secure" their future with the company.
Why on earth would they want to "secure" their future with that company? Jobs in this industry are plentiful and it's very easy to be "secure" regardless of what any single company does. Even if you get laid off, you can walk into another job within a week if you have the appropriate skills.
Re:We're not even having the same conversation
on
The Post-Idea World
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· Score: 1
It's not just nostalgia or some historical distortion that things were different between the two world wars. There was relativity, Communism, anarchism, feminism/sufferage, the uncertainty principle, Bauhaus functionalism and a dozen other art "schools" organized around ideas, the incompleteness theorem, Freud, social Darwinism, logical positivism... and I really could go on and on.
I submit that part of what you're saying is just nostalgia. You're bringing up Communism, relativity, the incompleteness theorem, Freud, and logical positivism, but those ideas aren't from the same period. Those ideas span almost a century. You've compressed a century's worth of ideas into the single inter-war period, which is precisely the problem with our evaluation of the past: we compress it and pay attention only to the highlights. Freud was not a contemporary of A.J Ayer.
Granted, there may be less discussion now of the ideas you mentioned (like communism). However the reason isn't because people are less intellectual, but rather, because there is consensus now, and many of those ideas are discredited. Almost everyone agrees on Democracy and some form of capitalism. The remaining questions involve things like how much regulation we should have of banks.
Part of the reason there's consensus now is because some of the ideas you mentioned (like Communism and Social Darwinism) were frankly idiotic to begin with and were popular only because they're so amenable to vulgar forms.
For example, Marxism was totally idiotic to begin with. I'm not talking here about the failure of communist economies. I'm talking about the economic ideas of Marx, with which I'm very familiar. Marx deduced everything from the labor theory of value, which is easily refuted and could be proven false at the time, and which was refuted to any reasonable person's satisfaction within a decade of Capital's publication. But it's not just that; almost every page of Marx is filled with severe intellectual errors or obvious problems, and almost every prediction of his was refuted almost right away by events. Marx was a second-rate mind, if even that, and almost everyone within academic economics rightly thought so. Quoting Keynes: "Marxian Socialism must always remain a portent to the historians of Opinion — how a doctrine so illogical and so dull can have exercised so powerful and enduring an influence over the minds of men, and, through them, the events of history."
I suspect Marxism prevailed because it was a theory so capable of simplification and vulgar understanding. What most people meant when they said Marxism, was something along the lines of "greedy people are stealing everything through profits, and if we just get rid of those people, and just care for each other, and pass laws that all wages must be much higher, then everything will be wonderful." Marxism is a perfect vulgar opinion: it reduces all our problems to a single cause (greedy businessmen and their profits), it locates an identifiable group within society which is responsible for everything bad, it posits a promised land if we just do x, it can be easily reduced to a few sound-bites even if they misrepresent the original, it has a mystical core doctrine which nobody has read, and so on. Frankly it's like some of the other "ideas" you mentioned: social Darwininsm, Anarchism, and even Fascism (which you didn't mention but was certainly prevalent during the period you're talking about). These aren't really "grand ideas" but rather vulgar ideas. If anything, the inter-war period you speak of was when everyone thought he was an intellectual. I'm not sure that was better. It was definitely worse in some of its consequences.
Many people here (myself included) have wondered how this is even supposed to work. In the original article, the inventor claimed:
[He was] emphasizing his system is “subcritical.” This means no nuclear reaction occurs within the thorium. It remains in the same state...
In which case it's not clear at all how he's generating so much energy from such a small amount of weakly radioactive material.
So I went to the guy's website (laserturbinepower.com) and read a very short article called "thorium trigger". It claims:
Nikola Tesla, who did a lot of experimental work with Electromagnetism, suggested that some type of ray may trigger radioactive decay. Others have taken up this idea and have proposed various ideas about what the rays could be. Some suggest neutrinos, since they are associated with nuclear reactions and are detected by their triggering a nuclear reaction. If neutrinos or some other agent trigger nuclear decay, an increase in the presence of this agent would accelerate nuclear decay....
The required intensity parameter zf _O (1) can be achieved with a laser, but the small temporal duty cycle is disqualifying. For example, the requisite intensity could be supplied by a Ti : Sapph laser with a pulse length of 100 fs (1013 s) at a repetition rate of 1 kHz (103 s1).
There was also some more material on a page marked "cars":
One small problem, Cadillac has no intension to build [a nuclear car] until the year 6000! The second problem is the the Cadillac design is based on a REACTOR which would weigh over 5000 lbs. not very practical...
Laser Power Systems is developing a power system that weighs only 600 lbs. producing 250 H.P. with hopes of producing cars in the next 2 to 4 years.
Presumably he means that this does not use a reactor.
It appears he's relying on some effect of accelerated decay, where decay is sped up by a laser, without any nuclear chain reaction (not even a subcritical one).
I googled for "accelerated decay" and found that this effect has not been demonstrated in a laboratory. Although a few independent researchers claim they have observed the phenomenon during their experiments, the most recent claim of accelerated decay was rebutted by the Lawrence Livermore Lab, here.
Still, the article still makes little sense to me from a physics standpoint. The article claims:
emphasizing his system is “subcritical.” This means no nuclear reaction occurs within the thorium. It remains in the same state
...in which case it's not clear where the heat is coming from. Not from fission, apparently. Not from decay heat, which would be trivial in this case. If we're relying on e=mc^2 to generate heat in this case, then it's not clear how this is happening when there is "no nuclear reaction" and "it remains in the same state".
Perhaps he's referring to a subcritical reactor which requires a laser to sustain, and he misspoke when he said "no nuclear reaction" and "it remains in the same state." I can only guess he meant a subcritical reaction. In that case, there's the possibility of a meltdown. Even if the reaction ceases immediately upon shutdown (as it would in a subcritical reactor) there are still decay products generating tremendous heat. Granted, this kind of reactor wouldn't generate actinides but it still would generate short-lived fission products. Perhaps he means that the car can only be driven for 8 hrs in a row or so, after which it would be shut down for 8 hours to prevent any accumulation. Who knows.
I'm not able to make any sense out of it either. The article says:
Stevens agrees, emphasizing his system is “subcritical.” This means no nuclear reaction occurs within the thorium. It remains in the same state...
...in which case it's not clear where the energy is coming from. It's apparently not coming from fissioning or from breeding some fissile element. It can't be coming from decay heat which would be extremely trivial in this case.
Is he claiming that heating an element will cause it to decay more quickly?
JIT is a catchword euphamism [sic]. It came into being because "interpreted" became a dirty word when compilers became available to the masses.
Nope. JITs or similar things have been around since the early 1960s, long before compilers (or even computers!) became available to the "masses". However the term "JIT" was popularized by early Java vendors (circa 1996-1997) to distinguish their products from Sun's early Java VM, which interpreted each instruction and so was horribly slow. The term JIT was popularized because of JAVA, in 1996 or so, and meant "NOT bytecode interpreted one instruction at a time" as was Java 1.0.
Neither the technology of selective compilation, nor the popularity of the term "JIT", occurred when compilers became available to the masses. Neither the technology nor the term were caused by the reason you cited.
The reality is, JIT "compiling" is simply a somewhat more efficient interpreter.
You call it JIT "compiling", but there is no reason for the quotation marks. A JIT is actually compiling.
*sigh* I hate having to explain this every time. Makes me feel old.
Heh. I don't know how seriously you expect me to take a remark like that.
I can relate. Doing it over and over again makes me feel old too.
I hope you guys weren't think you could say "I'm old" and then others would infer some kind of expertise as a result. I'm not young either, but I don't mention the fact in support of arguments about interpreters.
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Man, nobody disputes that. I UNDERSTAND that. But it does NOT explain how a greenhouse works. While it's true, it's NOT THE PRIMARY MECHANISM of a greenhouse.
NO. That is one possible explanation for how a greenhouse works, but NOT the correct one.
Look, there are SEVERAL mechanisms of heat loss (convection, conduction, radiation) happening SIMULTANEOUSLY. Furthermore, a greenhouse does SEVERAL things simultaneously. A greenhouse allows light through, which heats the ground, which heats the adjacent air, but the glass prevents hot air from floating up into the broader atmosphere and pulling cold air downwards (in other words, a greenhouse prevents convection over a wide area). ALSO, at the same time, a greenhouse allows visible light through the glass, and that visible light heats the ground, and the ground emits IR radiation, but the glass is somewhat opaque to IR radiation, so the glass re-radiates IR downward, and heat doesn't escape. ALSO, a greenhouse allows heat to enter from the outside, and the heat "tries to get out again" (as you said) but some of it is reflected back inward. SEVERAL of these things are happening AT THE SAME TIME. A greenhouse prevents SEVERAL different mechanisms of heat loss, all at once. The question is: WHICH ONE is primarily responsible for the heating effect?
With me so far?
Don't just REPEAT one of these effects. Doing so answers absolutely nothing! The question is: WHICH EFFECT is most important. You cannot answer which effect is most important, by just repeating ONE of the effects. You must do an EXPERIMENT to find out which is the most important.
The question of which effect is most important, has been answered by experiment and theory. The PRIMARY mechanism of greenhouse heating is the PREVENTION OF CONVECTION. The OTHER effects listed (reflection of heat, etc), while they are occurring, are FAIRLY NEGLIGIBLE. I UNDERSTAND the other effects, it's not that I don't get what you're saying. But those effects are NEGLIGIBLE in explaining why greenhouses are hotter.
This explanation is what ALL the sources clearly say. This explanation can be demonstrated by easy experiments. It's what I've been saying all along, apparently unsuccessfully. Again, from wikipedia: "the greenhouse re-radiate some of their thermal energy in the infra-red, to which glass is partly opaque, so some of this energy is also trapped inside the glasshouse. However, this latter process is a minor player compared with the former (convective) process. Thus, the primary heating mechanism of a greenhouse IS CONVECTION [my emphasis]."
When you respond:
Look, I apologize for any nasty remarks. I shouldn't have responded in that way. I'm sorry if I offended you.
Let's just let it drop.
NO.. ONCE AGAIN, a greenhouse works by preventing convection from the INSIDE to the OUTSIDE of the greenhouse. As a result, a vacuum INSIDE the greenhouse is totally irrelevant because it HAS NO EFFECT on whether convection is happening from the inside to the outside. You would need a vacuum over the entire surrounding atmosphere to tell if convection (with the WIDER ATMOSPHERE) is the cause.
That explanation is simple but it's WRONG. Once again, from wikipedia: "Thus, the primary heating mechanism of a greenhouse is convection." That's totally obvious and unambiguous!
The wikipedia article specifically says that the explanation you offer is INCORRECT, as does the original linked article.
You haven't responded to ANYTHING in my posts, which is weak even as a troll!
You obviously haven't known about this for decades, because you don't know about it now. Instead, you had an elementary misconception for decades.
You cling to your misconception, because your fragile ego prevents you from admitting your error, despite multiple sources which tell you over and over again that you're wrong.
You truncated the first quotation, and misread the second.
The quotations should have been:
The original claim was that greenhouses work by preventing convection with the wider atmosphere. Maybe I should have spelled that out more; maybe that was the source of confusion.
Of course there's not some barrier within the greenhouse preventing convection inside. That was never the claim. The glass prevents convection from the inside of the greenhouse to the outside of it.
There's no extra mode of heat transfer being added here. The original article was talking about convection with the wider atmosphere, and that's what my original post was about. The entire thread has always been about that mode of heat transfer.
No. You can't determine how a greenhouse works from sketching a steady state diagram of energy flows. The steady state diagram is compatible with multiple explanations. You must determine what has changed by the addition of a greenhouse.
Of course opening the window changes the system. Every experiment changes the system, including your vacuum experiment--but the vacuum experiment doesn't yield an answer here since the result would be the same regardless of how a greenhouse works. I wanted to replace your vacuum experiment with one which determines what the correct answer is.
Don't worry; I write really fast, and it actually takes me only 5 minutes or so to compose a reply. The reason for the long delay between my responses was because I was on the road and can't type fast on my droid, so I waited.
Ok, but this isn't important. Nobody was arguing that convection inside the greenhouse was the important factor. The claim was that a greenhouse prevents convection with the wider atmosphere.
It doesn't matter if the greenhouse loses all its energy as IR radiation. The question is whether a non-greenhouse area of ground loses all its energy as IR radiation. The question is: what is changed by the addition of a greenhouse. If a greenhouse loses all its energy as IR radiation, then this could mean that convection over a wide area was prevented, and IR radiation is the only remaining route of energy loss.
This is directly and clearly contradicted by all the sources on this issue. Furthermore, what you say is clearly not what the linked article says, which clearly states that greenhouses work by preventing convection over a wide area. From the article: "In a greenhouse, this mixing [convection] is confined to the layer of air trapped under the roof, so there is a much smaller mass to be heated. Essentially, the large kettle full of water has been replaced by one with half an inch of water on its bottom, and as a result the water will warm up much faster." I just don't see how there is any other interpretation.
And something similar is said by all the other sources I've read on this topic. They are very clear and straightforward in claiming that greenhouses work by preventing convection over a wide area. They also leave no room for interpretation. They are perfectly clear about this point. For example, here is a sentence from the first paragraph on the wikipedia article about greenhouses: "Thus, the primary heating mechanism of a greenhouse is convection." I just don't see how there is any alternative interpretation of that.
Saying that "it [preventing convection over a wide area] really has nothing to do with the way greenhouses are warmer than normal buildings" appears to directly contradict these sources.
The question was: why is a greenhouse hotter than a non-greenhouse, which can be either: 1) it prevents convection over a wide area; or 2) the glass absorbs and re-emits IR radiation and heat downwards back into the greenhouse. Replacing air in the greenhouse with a vacuum, would offer no way of deciding between these two hypotheses, because the vacuum-greenhouse experiment is compatible with both hypotheses. A vacuum-greenhouse would do both; it would re-emit IR radiation and also prevent convection.
The way to decide between these two hypotheses is to have a greenhouse that has a small slit near the bottom and another on the top, which you can open and close using vents. If greenhouses work by absorbing and re-emitting IR radiation, then opening the vents should make very little difference to the heat inside. If, on the other hand, a greenhouse works by preventing convection with the wider atmosphere, then opening the vents should make a huge difference. In fact, it makes a huge difference, as you can see by cracking your windows on your car during a hot day. This is because a greenhouse works by preventing convection with the wider atmosphere, as is claimed by the linked article and the other sources I have.
I wasn't arguing from authority. I was referring you to source material written by someone who has expertise in this area, and who knows more about it than you do.
You could also have typed "greenhouse" into google and found many other cogent explanations of how greenhouses work; but I suppose those also are "calls to authority."
With regard to "name dropping." You should look up that term, and think about what it means, before you use it. There was no name dropping in my post.
Really? The article doesn't support what I'm saying? From the article:
And from my post:
Do you really think that the article doesn't support what I wrote? It's perfectly clear. Read it again, more carefully.
You also claim that I'm taking the analogy too far. You wrote:
You didn't understand the conversation to which you're contributing.
I wasn't the one drawing an analogy between the earth and a greenhouse. That was the other side.
Again: read and understand the material before responding.
The only "game" here, is that you ran your mouth off, without reading or thinking first. Then you got caught in an elementary mistake about how greenhouses work. But you weren't big enough to admit it, so you decided to continue running your mouth off. Then you made some more silly mistakes, and you incorrectly attributed the greenhouse analogy to me.
I'm not going to continue this silly conversation with you any more. This could go around in circles for a long time. I could point out any number of sources which explain how a greenhouse works, but you'll just say they're "appeals to authority," then spout more silly mistakes or try to change the topic. There's no way I can force you to read and understand the material.
You may also be upset about my harsh tone. However, you set the tone here. This was a dispassionate and adult conversation until you arrived.
Nope. Experiments were done in which two greenhouses were built, one from a material which blocks IR radiation and another from a material that doesn't, and both heated up at approximately the same rate. This is because a greenhouse works by preventing convection over a wide area. This experiment has been done many times and has always yielded the same result.
This issue is explained clearly in the linked article, by a professor of physics.
You're reading into my motives here. You're not responding to what I actually wrote! There was no reference to religious faith in my post.
Don't think about what I'm trying to accomplish, or what motivates me. Focus on the content of what I wrote!
I should probably elaborate (although it's not really important to the point here) that some glass does indeed block IR radiation. Some glass has coatings or materials added to block IR radiation. Nevertheless that's not how a greenhouse works.
Nope, you misunderstood what you read completely, and you didn't bother to read the posted article.
Nope, it shows you don't understand what you're reading. Please READ AND UNDERSTAND THE SENTENCE to which you're responding.
A greenhouse works by preventing convection over a wide area. Although convection still happens within a greenhouse, the thermal mass of air to be heated is far smaller, since the greenhouse prevents convection over a much wider area. As a result the interior of a greenhouse heats up much more quickly than an open area. As a result, a greenhouse works by preventing convection. Glass is not opaque to IR radiation.
This issue is clearly explained in the linked article, by a professor of physics. You apparently were unable to read more than the first paragraph of that article, and you badly misunderstood the sentence you read in my post.
You were the one showing ignorance of a very simple model--a model which could have been understood if you had bothered to read the article, beyond the first paragraph. You should have been able to read the entire article since it's about a page long.
Indeed, this is a failure of education. You simply cannot read, or you don't bother. You didn't read (or understand) the 1-page article from a professor of physics, and you didn't understand the sole sentence in my post to which you were responding.
Oops, you're right, I typed zero rather than O. Since they look so similar I didn't notice during the preview.
The globe is warming on average. This point is virtually undisputed, and is verified by temperature readings all over the globe and by satellite IR readings.
Furthermore, deserts are expanding; this point is also undisputed.
The reason they're changing the name from "global warming" to "climate change" is because the globe is only warming on average. Many places will get cooler as a result of climate change, because of changing ocean currents. Lots of people misunderstood this point. People have said "well the winters are getting colder here--so much for global warming!" which means they misunderstood the notion of average global temperatures increasing.
Changing the name from "global warming" to "climate change" isn't an attempt to mislead people; it's an attempt to un-confuse them.
Nope, a greenhouse works by preventing convection. The article you linked says this, and not what you claimed.
You may not have read the entire article you linked. It starts off by saying: "If you've ever heard an explanation of how a greenhouse works, it was most likely based on the differing transparency of glass to solar and thermal infrared radiation", but then the article goes on to show how that explanation is incorrect.
I definitely agree with you about C02 and global warming. I believe that global warming is occurring, and is caused by humans. However I must nitpick something you said.
You claimed that C02 traps heat, that we can test this, and that we emit lots of C02. Therefore, we are causing global warming.
However, even the global warming deniers usually admit this much. What they deny is the feedback effect, whereby a slight warming of the earth's atmosphere causes changes to Albedo, cloud cover, etc, which further enhances the warming. That's the contentious point.
The C02 by itself would raise Earth's temperature by only 1 degree celcius or so. It's the feedback which is really important, and which will raise the temperature by another 4 degrees or so.
The feedback effect depends on things like: how much ice will be melted, how much that melting will effect the reflectivity of the earth (albedo), how much methane will be released from melting permafrost, etc. These things are based upon calculations and sometimes models, and also upon paleoclimatology evidence which suggests that small changes in C02 caused disproportionately large changes in temperature. Unfortunately it's not possible to test feedback effects in a simple way with home experiments.
You seriously think that unemployment among programmers is "more like 25%?" Are you serious? Do you live in your own little world? I don't know a single programmer who is involuntarily unemployed at present.
Then you should be modded stupid. You think your own failure to get a job signifies something about the broader market for programmers.
I see I've been modded down to "troll" by pointing out something which nobody could seriously dispute.
That's just ridiculous and silly.
It's extremely easy to find a job as a programmer right now which pays highish wages relative to other jobs, and which doesn't require working 12-16 hour days. Although there is significant unemployment right now, that unemployment is almost entirely among the working class, and among people who used to be employed in construction etc, and among millenials. The unemployment rate among experienced programmers is 4% at present, meaning unemployment in that sector is almost entirely frictional. At my company, for example, we're trying to find qualified people to hire, but it's virtually impossible. In other words, the labor market for programmers is as tight as it's ever been, with the possible exception of the 1999-2000 timeframe.
Whoever is working 12-16 hour days for no additional money, for a year and a half, has made a silly choice, and has done himself harm for no reason whatsoever. He has many other easy alternatives, which he chose not to investigate or pursue.
Of course, there are many people in this economy who lack skills or experience, and who are seriously suffering. But here we're getting complaints from programmers who have careers in a field with 4% unemployment.
One needs only to type "software engineer pay" into google and come up with links like this one which clearly indicate that someone with a Bachelor's degree makes $60k-$120k per year (not including benefits), Or I could type "unemployment sector" and find that the unemployment rate for programmers is half the national average and that: "With an unemployment rate of under 4% in the tech sector, there’s a shortage of qualified technology professionals, TechFlash reports." Or I could type into google a query about how many hours most programmers work, and find from the Bureau of Labor Statistics that: "Most software engineers and programmers work 40 hours a week, but about 15 percent of software engineers and 11 percent of programmers worked more than 50 hours a week in 2008" which obviously means that working 12-16 hour days is rare. All this took about 60 seconds of research, but perhaps the people working 12-16 hour days never bothered to type these things into google?
Part of living in a capitalist economy involves looking at the options available to you and selecting the best one given your circumstances. I know there is always some rare person who says something like: "I paid $45,000 for a $25,000 car, because I didn't even bother to walk across the street to some other dealership to look," but it's rare and signifies nothing other than that some lone person got ripped off.
The odd thing is that there's constant complaining on slashdot among people, who are essentially highly privileged or fortunate workers. Programmers make $60-$120k for a Bachelor's degree and work 40 hours per week (which apparently is average, according to the BLS) with an unemployment rate of 4%. Clearly programmers are in the top 1% of workers worldwide, by a very comfortable margin, and are within the top 10% even among the rich countries. Nevertheless, they constantly insist on slashdot that they deserve much more than this and that they're the modern equivalent of slaves, that laws should be passed favoring them even more and that they should form unions etc.
I realize this will be modded down to "troll". Of course, there are a few modders here (not most of them, of course) who think that anything which challenges any idea they have in their heads is a troll. Ohwell...
You don't seriously think this. Working class employees are treated far worse, have fewer options, make far less money, get fewer benefits, are less secure, and have less rewarding work than almost any white-collar employees. Everyone know this. Why would people spend $100k on college education, and lose years of earnings, with no promise of a career, if everyone wanted a blue-collar job. Unions didn't work out for the employees of GM, or for that matter, almost any other unionized industry. What's in demand are skills and no level of organization will ever compensate for the lack of them.
I don't think you really believe this. Accounting is probably more important than software (this is coming from a programmer).
Try running a company with more than 3-4 people without some kind of accounting. And don't say "I worked for company x with 10 employees and they had no accountant" because they did have an accountant, just somebody who had other roles as well.
Even with a company that has only 3-4 people, somebody is doing accounting, if only in their heads. They're doing mental accounting, which is very simple, but it's still accounting.
We couldn't even collect taxes, or have a civilization, or pay employees without accounting. We could build nothing that required more than a few people, or required any kind of coordinated effort. Accounting made civilization possible. Accounting was almost certainly the reason people invented writing in the first place (numerals came first).
No, no, no. You can easily run a company without software, as all companies were run without software until quite recently. But you cannot run a company without some kind of accountant. Even the idea of "a company" requires wages at different levels, records of payments, retained earnings, planning, etc.
Then they're all just being dumb. Why would they do something like that. Right now they could easily find far better jobs that require working only 45 hours per week or less. I get calls from recruiters all the time. Don't those guys get similar calls? Why do they remain in such a job when there are so many obvious and easy alternatives? Are they just dumb or something?
Why on earth would they want to "secure" their future with that company? Jobs in this industry are plentiful and it's very easy to be "secure" regardless of what any single company does. Even if you get laid off, you can walk into another job within a week if you have the appropriate skills.
I submit that part of what you're saying is just nostalgia. You're bringing up Communism, relativity, the incompleteness theorem, Freud, and logical positivism, but those ideas aren't from the same period. Those ideas span almost a century. You've compressed a century's worth of ideas into the single inter-war period, which is precisely the problem with our evaluation of the past: we compress it and pay attention only to the highlights. Freud was not a contemporary of A.J Ayer.
Granted, there may be less discussion now of the ideas you mentioned (like communism). However the reason isn't because people are less intellectual, but rather, because there is consensus now, and many of those ideas are discredited. Almost everyone agrees on Democracy and some form of capitalism. The remaining questions involve things like how much regulation we should have of banks.
Part of the reason there's consensus now is because some of the ideas you mentioned (like Communism and Social Darwinism) were frankly idiotic to begin with and were popular only because they're so amenable to vulgar forms.
For example, Marxism was totally idiotic to begin with. I'm not talking here about the failure of communist economies. I'm talking about the economic ideas of Marx, with which I'm very familiar. Marx deduced everything from the labor theory of value, which is easily refuted and could be proven false at the time, and which was refuted to any reasonable person's satisfaction within a decade of Capital's publication. But it's not just that; almost every page of Marx is filled with severe intellectual errors or obvious problems, and almost every prediction of his was refuted almost right away by events. Marx was a second-rate mind, if even that, and almost everyone within academic economics rightly thought so. Quoting Keynes: "Marxian Socialism must always remain a portent to the historians of Opinion — how a doctrine so illogical and so dull can have exercised so powerful and enduring an influence over the minds of men, and, through them, the events of history."
I suspect Marxism prevailed because it was a theory so capable of simplification and vulgar understanding. What most people meant when they said Marxism, was something along the lines of "greedy people are stealing everything through profits, and if we just get rid of those people, and just care for each other, and pass laws that all wages must be much higher, then everything will be wonderful." Marxism is a perfect vulgar opinion: it reduces all our problems to a single cause (greedy businessmen and their profits), it locates an identifiable group within society which is responsible for everything bad, it posits a promised land if we just do x, it can be easily reduced to a few sound-bites even if they misrepresent the original, it has a mystical core doctrine which nobody has read, and so on. Frankly it's like some of the other "ideas" you mentioned: social Darwininsm, Anarchism, and even Fascism (which you didn't mention but was certainly prevalent during the period you're talking about). These aren't really "grand ideas" but rather vulgar ideas. If anything, the inter-war period you speak of was when everyone thought he was an intellectual. I'm not sure that was better. It was definitely worse in some of its consequences.
Many people here (myself included) have wondered how this is even supposed to work. In the original article, the inventor claimed:
In which case it's not clear at all how he's generating so much energy from such a small amount of weakly radioactive material.
So I went to the guy's website (laserturbinepower.com) and read a very short article called "thorium trigger". It claims:
There was also some more material on a page marked "cars":
Presumably he means that this does not use a reactor.
It appears he's relying on some effect of accelerated decay, where decay is sped up by a laser, without any nuclear chain reaction (not even a subcritical one).
I googled for "accelerated decay" and found that this effect has not been demonstrated in a laboratory. Although a few independent researchers claim they have observed the phenomenon during their experiments, the most recent claim of accelerated decay was rebutted by the Lawrence Livermore Lab, here.
This appears to be snake oil.
Still, the article still makes little sense to me from a physics standpoint. The article claims:
Perhaps he's referring to a subcritical reactor which requires a laser to sustain, and he misspoke when he said "no nuclear reaction" and "it remains in the same state." I can only guess he meant a subcritical reaction. In that case, there's the possibility of a meltdown. Even if the reaction ceases immediately upon shutdown (as it would in a subcritical reactor) there are still decay products generating tremendous heat. Granted, this kind of reactor wouldn't generate actinides but it still would generate short-lived fission products. Perhaps he means that the car can only be driven for 8 hrs in a row or so, after which it would be shut down for 8 hours to prevent any accumulation. Who knows.
I'm not able to make any sense out of it either. The article says:
Is he claiming that heating an element will cause it to decay more quickly?
I can't make any sense out of it right now.
I apologize if I was too testy with this remark. Your comment struck me as rude ("you might want to learn a little bit...") to that fellow.
I have no doubt that you have considerable knowledge about VMs. The problem here is that guys seem to be using the terms differently.
Nope. JITs or similar things have been around since the early 1960s, long before compilers (or even computers!) became available to the "masses". However the term "JIT" was popularized by early Java vendors (circa 1996-1997) to distinguish their products from Sun's early Java VM, which interpreted each instruction and so was horribly slow. The term JIT was popularized because of JAVA, in 1996 or so, and meant "NOT bytecode interpreted one instruction at a time" as was Java 1.0.
Neither the technology of selective compilation, nor the popularity of the term "JIT", occurred when compilers became available to the masses. Neither the technology nor the term were caused by the reason you cited.
You call it JIT "compiling", but there is no reason for the quotation marks. A JIT is actually compiling.
Heh. I don't know how seriously you expect me to take a remark like that.
I hope you guys weren't think you could say "I'm old" and then others would infer some kind of expertise as a result. I'm not young either, but I don't mention the fact in support of arguments about interpreters.