Wednesday, September 28, 2005

Strings on supermanifolds

There is a paper

by Tokunaga that advocates string theory on supermanifolds. Bosonic string theory may be defined on supermanifolds whose super-dimension is (26+k/k), he or she argues. That of course cancels the central charge - since the spin 0 worldsheet fermions carry c=-1 - and she or he also shows modular invariance. However I find it likely that these theories won't be fully physical in spacetime - for example they will violate spin-statistics relations, won't they?

Also, I wonder what the insiders among the readers think, after a year or so, about the status of mirror symmetry of supermanifolds. Has it passed the test of time?


  1. It's curious that people in academy, like those in a few blogosphere who all simutaneously talk about the same silly magazine that nobody reads. Those folks must be living on the moon since they can care less about a cruel reality that is unfolding on the earth! I don't understand that these people are so fun of talking about something none-exist and none-proven, while exibits absolutely no interest in something that exists and that's relevant to reality. What brane world do you live in?

    The world's oil has peaked, as indicated by the strongest evidence ever. Saudi oil administrator just claimed that overnight Saudi's recoverable oil reserve has increased from 260 billion barrel to 460 billion barrel, and without any new discovery, too. Why would he lie in such an obvious way that a 3 years old would not be kidded? Desperation of sort!!!

    Meanwhile, people have totally forgotten about Rita already. The worst scenary case has indeed happened, unfortunately. People read the news which say "the largest refinery in Houston was spared", and sighed a relief. Well, they MISINTERPRETTED the story. THE largest one was spared, but numerous slightly smaller ones, are NOT spared.

    Plus, the right turn the Hurricane took to avoid Houston, actually made matter worse by wiping out more of the off shore rigs and platforms. Rita landed as category 3 but it was a category 5 over the gulf! Most of the oil rigs were only designed for a category 2-3!!!

    You've got to read some related weblogs to learn those truths, before the bad news slowly leak out of the mainstream media:

    A few years down the road, I am not sure people study crackpot theories like super string, would still have a job at all? Since by that time, the only relevant research remaining would be to find alternatives to fossil fuels in order to salvage the human civilization. All other researches would become an unaffordable luxury the collapsing economy simply can not pay for.

    The fact is Sandi's oil has peaked and therefore the whole world has peaked. You are going to see the world oil production to decline by a few percentage per year from now on.


  2. Dear Quantoken,

    if you stop propagating on your GUITAR theory in order to focus on "peak oil" it is definitely a step in the right direction.

    On the other hand I do not see exactly what your point would be. I assume by now you sold your car, bought a bicycle instead and used the difference to invest in oil stocks. But what do you expect Lubos and other people to do? Stop string theory and start drilling at Harvard ?


  3. Wolfgang:

    I never propagated GUITAR theory in the first place. It's not finished yet and I am still spending time on developing it. Meanwhile I have just occasionally meantioned a few fundamental principles. That's hardly propagation. And it is surely not the kind of propagation the likes of Kaku does on TVs all the time.

    I am fully aware that the world's oil is finite and will one day run out but never paid too much attention to it, like most of other people do, and then something John Baez posted on his blog caught my attention and I realize the problem is much more imminent and more serious that I ever realized in the past.

    What will the likes of Lubos et al do, when the economy collapses and his job is no longer funded? I don't know. But it is clear to me that fundamental researches too far fetched from reality will be doomed pretty soon so his profession will be dead in a few years. When tax payers don't want to pay, or they can't pay, you don't get paid. It's that simple.

    Don't ask me what he can do by then. But isn't it something you want to talk about if it is so relevant to the very survival of human civilization, as well as survival of individuals? You want to talk about it whether something good can come out of the talking or not. It's human nature, unless you live on the moon.


  4. Some more nuclear/solar energy would be nice:

  5. John:
    The web link you provided are talking about pies in the sky.
    Neither nuclear energy, nor solar energy can provide enough replacement energy source in a quantity that matches what fossil fuel currently provides us. You don't get the point at all. There ARE plenty of energy around even after fossil fuel, but there will be no more cheap energy. That's the problem.
    Uranium is quite abundant in the earth crust, averaging about 4 ppm concentration. But you can not just scope up some soil and try to refine uranium out of it, if you do, you end up spend much more energy in trying to extract uranium, than the energy you eventually can get out of the uranium nuclear fission reacion. Likewise nuclear fusion is at least another half century away before it's technologically feasible, and even when it does become a possibility, it is not clear whether extracting fusion material from sea water will actually cost more energy than what you can eventually get in return.

    Trying to collect solar energy in the sky would be a much bigger pie in the sky, the energy cost of manufacturing the solar energy collectors, and launch them into orbit, would be several orders of magnitude HIGHER than the total solar energy you can eventually collect, over the lifetime of these devices.

    Anything that gives you less energy back at the end of day, than the energy you invest in the first place, is unworthy.

    Even for the "low tech" solar panels, those installed on the ground, the efficiency is still very low. Their current energy pay back time is around 10 years.

    The energy pay back time is the time the solar panels need to be in use and generate solar energy which is enough to pay back all the energy spend in manufacturing, transporting, installing and maintaining those solar panels. The current state of the art is 10 years. So if a solar has not been in use for 10 years, it actually costed us more energy to have, than the amount of energy it contributes.

    To understand how serious the crisis is in association with the depletion of fossil fuel, just think about how CHEAP the energy is provided by fossil fuels. One gallons of gasoline costs $30, and that's 1.5 kilogram. Each kilogram of gasoline releases 40,000 kilocalories. So that's 2.5x10^8 Joules of energy, all for the cheap price of US$3.

    Where else can you find energy so cheap once the fossil fuel is gone?

  6. About Uranium, my point is Uranium is every where but mostly un-economical energy wise to be extracted. The few rich uranium mines that are economical enough to mine, they don't provide anything near sufficient to provide our energy needs today. So they are actually a more limited resource than fossil fuels.


  7. Well there's this more detailed article that seems optimistic for nuclear energy.

  8. Dear Quantoken,

    several days ago you predicted that Rita would destroy North America. It directly killed one person and roughly 28 people were killed by the panic that people like you escalated.

    After this contribution of yours to the 28-fold murder, I would expect you to become less self-confident in your catastrophic predictions at least for 1 month. Thanks for your understanding.


  9. Lubos:
    Your prediction has already been falsified. You predicted that Rita will move slower and arrive "next week", it arrived saturday morning, so it counts as "this week", not "next week", since we count a week starting sunday. Also it is not "weak" as you predicted, it was category 3-4, slightly weaker but not weak. If you watch TV it moved whole houses in one piece for several miles away from their fundations. I would not call that weak.

    Before it landed it was a full category 5, wiping through the densest area of the off shore production rigs and platforms, with waves as high as 100 feet. Initial assessment is it caused more destruction to off shore production facilities than any of previous hurricanes.

    Mean while, my prediction came out completely right. I predicted that direct casualty of human life will be very low, and damage to oil facilities will be a much much worst problem than human loss.

    The fact remains that the world's oil production has peaked and this two hurricanes are a fatal blow. It takes time so you don't feel the pinch yet. But price of natural gas and heating oil has already near doubled from one year ago.

    When winter comes, this winter will be very miserable. A lot of people will be freeze to death since they can't afford the fuel to heat their houses.

    On a good winter, when the oil price is still not that high. An average household has to spend $400 per month in Boston just to keep the rooms warm. This winter it will be at least double or even tripple that. Lubos I hope your little apartment is small enough so you have enough money to heat it. A lot of poor people are not that lucky.

  10. John:
    I looked at the Uranium link you provided. This so called nuclear engineer does not seem to have the slightest clue what he is talking about, because he seem to be confused with the basic terminology.
    He repeated used the phrase "uranium ore", I do not know what he means by that phrase, but in English "ore" means the raw rocky material you dig out of a mine, before any processing or extraction is done. When the uranium ore is processed, you extract the uranium metal and it is in an oxide form, and it is commonly called "yellow cake" or "uranium cake". The author never made any meantioning of that phrase so he probably doesn't even know what "yellow cake" is.

    The author meantioned that the price of the uranium ore is $20-$40 per kilogram. Clearly, if you knock down a piece of the raw ore in a uranium mine, and you can sell it for $20-$40 a kilogram, it looks better than picking up gold from the ground, and I would have expected a crazy gold rush for uranium. Too good to be true.

    Again the author seems to be totally clueless and could not tell the difference between the raw uranium ore, and the refined product called uranium cake. The $20-$40 per kilogram price is probably uranium cake, not uranium ore.

    The rest of his article is not worth commenting since the author has no clue at all.


  11. This is from Associated Press:

    Rita wreaks havoc on oil rigs, platforms

    Lubos you can continue to burn youe head in the sand but that doesn't change the reality a bit.


  12. Does any one understand what the numbers mean? Those are official numbers from the government report, not something I made up.

    At least 1.7 million barrels a day of refined product are shut in and there is not even an estimate when these production can resume. Note we are talking about refined product, not crude oil. In an oil abundant era that would be no problem at all since you just import more. But at the oil peak, every one is in shortage so who do you import from?

    What does 1.7 mbpd refined product mean? One barrel is 42 gallons. So 1.7 million barrel a day is 71.4 million gallons a day. An average American car drives at 20 miles per gallon. So that's 1.428 billion miles lost car mileages per day, almost enough to make 8 round trips from the earth to the sun and back!!! That's one day.

    Assuming there are 50 million American cars being actively used on a daily basis for daily commute. 1.428 billion mileages lost per day amounts to 29 miles lost driving per car per day.

    Can you appreciate what kind of distruption it is, to require each actively used American cars to drive 29 miles less, each day!!! I drive 50 miles round trip to get to work each day. I don't care what the gas price is I need to drive that number of miles and not a mile less. Imagine what it would require to squeeze every American car to drive 29 miles less each day. What kind of demand destruction it takes to make up the shortage!!!

    Read this again.


  13. Yes the $20-$40 is for the uranium cake, engineers don't always dot all their i's and cross all their t's when writing for the general public. When writing for other engineers we (I was one for IBM) throw in lots of buzz words so you can't tell if the i's and t's are OK :-) Here's that nuclear engineer proving he knows some buzz words.'james%20hopf%20bnfl'

    By the way for the original article, he is assuming lots of engineering progress, we engineers do that too!

  14. John:

    Not only that author is not a qualified engineer. He is a complete idiot imcapable of logic.

    Let me quote his first paragraph from his paper.

    I recall reading studies in the 1970s that earnestly stated that we only had ~20-30 years of oil and gas reserves left (based on proven reserves, and the rate of consumption back then). In other words, we would have run out already. Needless to say, those predictions didn’t pan out.

    The original prediction actually pan out pretty good. The problem is this author's memory does not serve him. The "we" was for USA, not the whole world. And the original prediction calculated using the USA production rate in 1970, i.e., how fast we consumed the oil reserve. If you divide the number of known USA reserve by the annual reserve consumption rate in 1970, you get 20 to 30 years. But 1970 was the USA peak oil and the rate of production has been downhill ever since, and we have been importing 60% of the crude oil we use each year. We won't be able to last 20-30 year on our own, without huge oil imports. Now if the oil of the whole world has peaked, where do we import oil from, from another galaxy?

    Now about Uranium. The currently known uranium mines that's economical to mine, would last 50 years, but at CURRENT consumption rate. Note the current uranium consumption rate is very low. If the oil is running out, you would have to ramp up Uranium consumption several dozen times higher to provide enough energy to make up for the depleted fossil fuel. Then at the ramped up consumption rate, the Uranium probably lasts at most one or two years, instead of 50 years.

    And it would have been totally stupid to spend trillions of dollars to massively build nuclear power plants every where, only to find you run out of the uranium after just one or two years!

    Granted there hasn't been very active exploration for uranium mines in the past, so it's possible you could find more if you invest more resources to find them. But keep in mind over hundreds of years, the surface of the earth has received very well and thorough geological surveilance, if not for Uranium, then for other minerals like oil or precious metals. Very likely you were looking for oil but you stepped onto it and find it's a uranium mine, hence discover it unintensionally. So there may not be too much room for any additional discoveries.

    The author then talks about lower gredient Uranium mines, or even sea waters. The fact is uranium is contained in almost everything around us. But when the concentration is low, you would have to spend way more energy to extract it in the first place, than the energy that you can eventually recover from the nuclear fuel. So that makes it a useless energy source. It is not a matter of cost in dollar, it is a matter of cost in terms of energy.


  15. Yes for that 20-30 year projection, I can't believe he was knowingly complaining about people forgetting about foreign sources since his article was for a site worried about foreign dependence. He does though realize there's only a few decades of oil left now. For seawater, you do need new technology developed, specifically reactors that get more energy out of a given amount of Uranium. This engineer does realize new technology is needed.