By Sean Carroll | April 28, 2008 1:13 pm

I’m going to take a vacation from blogging for a little while. Partly a mental-health break, partly a need to get other stuff done. But there are many things I would love to blog about! So here is a list of recent stuff I’ve saved — you can fill in for yourself all the illuminating and entertaining words that would undoubtedly accompany a full-blown discussion.

  • Algae! The Editors chide me for carelessly conflating ethanol and biofuels. Fair enough. If algae are a clean and efficient way to capture and store energy from the Sun, I’d be all for it.
  • Meanwhile, we continue to heavily subsidize corn for ethanol, and as a result people are dying.
  • Don’t like your government? Take to sea and create your own!
  • At some point I will say more about Ben Rosen’s great blog, and especially Harold Rosen’s great entry for the Google Lunar X-Prize, about which Deborah Castleman blogs here. Private ingenuity will be crucial to the future of human spaceflight, especially when NASA can’t remember how to replicate its heat shields from the 1960’s.
  • I was going to score some non-partisanship points by criticizing Barack Obama for peddling nonsense about autism and vaccinations, just as John McCain does. (Hint: there is no connection!) Then I noticed that Hillary Clinton does the same thing, sadly. And, worse, Clinton has bought into John McCain’s panderiffic notion of declaring a summer holiday on gas taxes — at least Obama has come out squarely against that. (Encouragement to burn more fossil fuels is probably not sound policy.)
  • You might also be interested in Michael Berube’s rundown of the candidates stances on disability issues. McCain’s, you’ll be unsurprised to hear, consists of exhortations along the lines of “Hey, disabled folks! Suck it up!”
  • John McCain doesn’t want you to forget that Barack Obama is the preferred candidate of Hamas. He’s also the preferred candidate of nearly everyone outside the U.S., but whatever.
  • At The Corner, Michael Novak continues Jonah Goldberg’s project of portraying Fascism as left-wing. His evidence is that a friend of Albert Camus’s joined the Nazi Party because everything in the world had lost its meaning. Novak seems to miss the fact that this anecdote proves the opposite of his point — Camus’s friend became a Nazi because the Nazis provided “a meaning in the destiny of our nation,” not because they denied the existence of objective meaning. But keep trying!
  • Gerard ‘t Hooft proposes a locally finite model for gravity. A related discussion of whether the universe is continuous or discrete appears in an article from FQXi, which is annoyingly only available in pdf. I actually think the universe really is continuous, not discrete, for reasons that might become clear if I can just get this paper finished.
  • Tomorrow, April 29, is Duke Ellington‘s birthday. He was the master.

    And here is the orchestra, with Paul Gonsalves on tenor.

  • Oops, almost forgot this one: Cosmo Girl! suggests you should design your own religion, just like you design your favorite Starbucks coffee beverage. (Simile theirs.)

Be excellent to each other.

  • Wayne

    All the best in your off time. Great topics here: Algae, ethanol, politics, music, private spaceflight investment, and stirrings of a continuous universe. I like it. Well composed Sean.


  • Brian Mingus

    I am extremely disheartened that every single candidate for president gives credit to the supposed vaccine autism connection. I can only imagine that this is because they are being lobbied hard by families like this.

  • Moshe

    Fundamental discreteness breaks Lorentz invariance. Fairly model independent analysis (of RNG flow) makes this violation large at observable energies, even if it starts out small at high energies. So, unless there is an counter-argument (and there may well be), the idea is experimentally falsified. That’s not to say this is not worth thinking about, but progress will depend on overcoming this hurdle (among other things).

  • anonymous

    Sean: “Be excellent to each other.”

    Party on , dude!

    (Bonus points for the Bill and Ted’s quote, if you dare to claim them. 😉

  • Sean

    I think the “discreteness” under consideration is of the set of degrees of freedom (e.g., dimensionality of Hilbert space), not of spacetime itself. The Hawking-Bekenstein formula seems to imply that what happens inside a black hole can be described by a finite-dimensional Hilbert space. Some people want to extend this to the wavefunction of the entire universe, but I don’t think that’s the right direction to take.

  • Moshe

    Yeah, that wasn’t a comment on the ‘tHooft paper which I haven’t read, more on the PDF file which, like many other discussions on discreteness somehow manages to avoid the issue of Lorentz invariance.

    As for the finite dimensional Hilbert space story, the entropy of any conventional system (say an ideal gas) is a finite number, proportional to the number of DOF (say the number of species of ideal gas). None of those systems has a finite-dimensional Hilbert space.

  • Ginger Yellow

    Cosmo Girl’s idea for choosing a religion seems a lot better than the top down, indoctrinate your children variety.

  • Neil B.

    I sure hope algae are a clean and efficient way to capture and store energy from the Sun because we need something to make up for the flattening and eventual decline of oil supplies – even as demand continues to rise, for now. (Google for “peak oil” and peak just about anything else, including uranium.)

  • Ijon Tichy

    Interesting topics as usual from Sean. He’s the only reason I read this blog. Even if I disagree with him frequently. Like …

    1) Who cares about algae? We have a solution to our energy problem. It’s called nuclear fission. It will last us at least millions of years (and that’s ignoring any technological advances), it’s cleaner than anything out there, and it’s cheap as well.

    2) Running out of oil. Good. Hopefully that will mean the demise of our dangerous and addictive car lifestyles, and the return of cities that are designed for human beings.

    3) “Private ingenuity will be crucial to the future of human spaceflight…” Ha ha ha! Ingenuity comes from government organisations or from monopolistic corporations. The private sector comes in right at the end when there is money to be made, and there’s little to no ingenuity involved in that.

    4) So NASA can’t replicate 1960’s technology. See, Americans, this is a perfect example of wish fulfilment. You hate “the government” for long enough and intensely enough, it eventually becomes as bad as you fantasised it to be.

    5) McCain, Clinton, and Obama. A nut, a psychopath, and a magical thinker. You Americans are in deep … err … biofuel.

  • Anastasia

    Funny, I’m about to take a vacation and am hoping to catch up on posting!

    I have to admit some surprise that you chose the Klein article to represent the food crisis. There are far better ones out there. Regardless, connecting the dots from ethanol to the rice shortages is shaky at best. A whole pile-up of things is causing the problems, with ethanol only a small (if at all significant) part of it. I’ve written a bit about the confusion over food prices here and about the rice shortages here. I’m also surprised at the shortsightedness of people who are so quick to condemn biofuels as a whole. Researchers of all types are rushing to make cellulosic ethanol a reality, among other 2nd gen biofuels. Making corn ethanol the boogeyman will dry up funding for future alternatives. We do need to hurry up with nuclear, but (unless all transportation becomes electric) we still need portable fuel.

  • Neil B.

    Ijon Tichy, your impressions of (presumably) uranium supply are a common misunderstanding. You had better look at “Peak Uranium” on Wikipedia. Unless we build a viable breeder economy, our uranium will start running out rather soon as well. Maybe Thorium (one of my favorites) can help, maybe not.

    BTW, I find your name interesting. What nationality if you please? Around Eastern Europe? tx

  • Neil B.

    Anastasia, please look into and write about using industrial-grade hemp as a source for biofuel. See here at The hemp doesn’t need the pampering and energy input of corn, and the oil isn’t that hard to get out. I rode in the Hemp Car (a slightly modified diesel station wagon) a few years ago, it ran great.

  • Carl Brannen

    The problem with blaming ethanol for starving people is that US exports of wheat and corn this past season were at near record levels. Here’s the official export data, at least look at the data before you jump to conclusions.

    The reason people are starving is becaus (1) they are poor, and (2) harvests in the rest of the world are down. As the above article states, “The elevated level of 2007/08 U.S. wheat exports is unlikely to be maintained to these regions when supplies of other major competitors return to more normal levels.”

    The often quoted “$0.51 per gallon” subsidy for ethanol is not a subsidy per se, it’s a reduction in the federal taxes collected on that portion of the fuel. And it does not amount to $0.51 that you pay at the pump for gasoline blended with ethanol it is on the ethanol portion only. Example: if you buy 100 gallons of pure gasoline, the feds will collect a tax of $51. If it is 4% ethanol, the tax will be reduced by $2.04 to $48.96.

    The per gallon subsidies for biofuels are for biodiesel.

    Poor people are starving because they are poor. So long as fuel is expensive, it will be turned into fuel because that is simple economics. Even if it is outlawed in the US the result will just be that the distillation will happen overseas (and that many more jobs will be lost from the US). Furthermore, the poorest of the poor overseas are the rural poor and these are helped by biofuels because it increases the value of their crops.

    The starvation is just an arguing point (and a temporary one at best). The real ecological argument against biofuels is that it is bringing more farm area under cultivation. The 40 million acres that US farmers are paid to not farm are being farmed again (20% for last year, this year who knows), and rain forest is being turned into farmland in the tropics. This is what is really bothering the ecologists. They would prefer that we reduce our need for transportation to be so low that we can supply it with biofuels grown on the land we are already farming. Except that they’re against “factory farming”, so that would first require a massive population decrease.

    Nor is the corn used for directly for human food. We feed “field” or “dent” corn to animals and then eat the meat. And another large proportion of it is sent to factories that turn it into “corn syrup”. I would think that turning it into fuel would be better than making meat and sugary soft drinks out of it, but politics, and ecology, makes strange bed fellows. I guess the poor people in the rest of the world are straving because they need more coke and hamburgers.

  • Lab Lemming

    If we had a million years of uranium left, then my boss wouldn’t be paying me twice my former academic salary to find more of it.

  • Ijon Tichy

    Here are my arguments (well, really just a collection of facts) for millions (perhaps billions) of years of nuclear fission power:

    1) Until very recently, the amount of effort and money that has gone into uranium exploration has been tiny, partly because of uranium’s historically low price. Simply increasing that effort will increase our proven reserves significantly (like it does for every other resource), and the recent evidence suggests this is what is happening.

    2) You don’t believe me that proven resources can rise as a result of increasing exploration? From 2003 to 2005 the proven uranium reserves recoverable at less than $US130/kg rose by about 50%. Reserves are always associated with a price, because typically the more you’re willing to spend on recovery the more you can extract.

    3) Based on excellent geological data, one can make estimates of additional reserves, and that value is currently around 8 times the proven reserves, although of course highly uncertain. Again, this is similar for many other resources.

    4) Thorium is three to four times more abundant than uranium, and can also be used as a nuclear fuel. Even better, all of the thorium mined out of the ground is potentially usable in a nuclear reactor, compared with only 0.7% of naturally-occurring uranium.

    5) Breeder reactors, a proven technology, can utilise U-238 (the non-fissile part of naturally-occurring uranium). They can also use depleted uranium. This multiplies uranium resources by a factor of 60. And this is only for once-through operations; recycling is what fast breeder reactors were really designed for, but I won’t talk about that here.

    6) In the very long term we can extract uranium from seawater, and rivers annually replenish the seas with 32,000 tons of uranium (which vastly exceeds what any civilisation on this planet would need). Currently this is at least an order-of-magnitude more expensive than normal uranium mining, but we are talking millennia into the future. Feel free to believe that the technology (as well as costs) on this will stand still for thousands of years.

    7) Reactor technology continues to get more efficient. The third-generation reactors that have already been built and are continuing to be built have longer lifetimes, use a higher burn-up to reduce fuel use, they’re cheaper to build, simpler to operate, and they’re safer as well. Fourth-generation reactors are now being researched & developed, and they promise even greater improvements.

    8) The cost of nuclear power is very insensitive to uranium prices, because the cost of the fuel is such a tiny fraction of the total lifetime cost of a nuclear power plant. You could increase the price of uranium by a factor of 10, and add only 1 cent per kWh to the cost of nuclear power.

    So there’s our base-load energy needs taken care of virtually forever. Supplement it with hydro and other minor sources of power, and there is no energy problem whatsoever. All that remains is a political problem.

    Meanwhile, keep pushing the diffuse forms of energy like wind and solar (diffuse is why they’ll always be more expensive than nuclear), keep scaremongering about nuclear, and the coal industry will thank you (silently), while poor people stay poor, developed nations stagnate (materially and psychologically), and the climate goes to hell.

  • Ijon Tichy

    Funny, point number 8 is a smiley face with dark glasses.

    Neil B: Ijon Tichy is the main character in a series of silly but clever short stories by Stanislaw Lem. My recent ancestors are Croatian.

  • Carl Brannen

    “industrial-grade hemp as a source for biofuel. See here at The hemp doesn’t need the pampering and energy input of corn, and the oil isn’t that hard to get out.”

    As soon as America’s factory farms start planting millions of acres of conservation reserve lands in hemp the ecologists will complain about it for pretty much the same reasons as they complain about corn or anything else. Yes, you can plant small plots of hemp without having pests, but as soon as you plant 100 million acres of it, Nature will find a pest that will grow in it explosively and you will find that factory farms will have to use pesticides and genetic modifications to keep the game going.

    Now stamp out that reefer and put your thinking cap on. What happens when you take a plot of land and don’t farm it? Does it end up growing a pure field of hemp? Of course it does not. In the plains, land ends up growing grass. Farther west, it becomes a forest. Along the way, you will have to do something to that crop to keep it a hemp crop and that “thing” is going to be the things that ecologists complain about with regard to factory farms.

    As far as burning hemp (or other biomass) for energy as suggested in the link, most of the readers are probably not familiar with what one has to go through in order to get a permit to burn, in industrial quantities, things like this.

    If it were possible to get air permits to burn corn stover at ethanol plants in the US it would be done already (just as the leftover sugar cane is burnt in Brazil). The reason it isn’t done here is because to do it, we would have to get an air permit. And the air permit would probably be impossible to receive, but we wouldn’t discover that until a half decade had gone by because that is what happens to new industrial pollution ideas in the US nowadays.

    Permitting a corn ethanol plant is fairly easy. In your filings, you simply point to someone else’s corn ethanol plant and say that your process is similar to theirs, and since their pollution has been tested and is within the statutory limits, so will be yours. When you design something new, you can’t use this.

    This is also why cellulosic is at least 10 years out. Eventually someone will get a permit for a cellulosic plant and then it will be built and then its actual pollution will be monitored and then the information will fall into the public domain. But until then, it is utterly impossible for the majority of small companies like ours (and the majority of potential builders) to build a cellulosic ethanol plant. We have to wait until some huge conglomerate, or a university, goes through the initial permitting process.

    However, when cellulosic does become proven, this country’s corn ethanol plants will be converted over. The conversion is fairly simple, it’s mostly a change to the feedstock. Once you get the cellulose turned into sugar, the rest of the distillation is identical. And there will also be minor changes to the byproducts, but I think the same centrifuges will be good so there shouldn’t be any real deal breakers on it. Certainly the heart of an ethanol plant, the distillation towers and the fermentation tanks, will be unchanged.

    And I hear a lot of people that say that corn ethanol can only provide 6% of the US needs for transportation fuel. Great, let’s wait until we are so much out of oil that US transportation is down to 5% of its current size. Conservation is forced on us by economics. Nobody owns a car, everyone uses a bus. No one flies. The military is grounded, etc. Then we can turn to ethanol and even export 20% of it. But don’t you think the transition is going to be easier if we get the ethanol started while we’re still a wealthy country?

  • The Almighty Bob

    Carl, please; you argue well, and back your points admirably. But none of that matters if you ignore the most basic tenet of discussion: brevity. It means you will still have an audience when you’ve finished your well-argued point. (“,)

    Ijon, I think everyone’s squeamish about nuclear for the same reason: where do you put the bloody waste?

  • John Ramsden

    A couple of years ago on sci.physics I posted a suggestion that nuclear power plants should be built deep underground, so they could be effectively disposable in place (along with a load of low-level waste), readily sealable in the event of catastrophe, and the nuclear components safe from attack by terrorists and perhaps even hostile nations.

    I hoped for a decent discussion but, sci.physics being what it is, soon became embroiled in a slanging match with the resident baboons. However, amid the clamour, we did cover some angles, such as the expense and casualty rate of building the tunnels (manageable, I think we concluded) and one alpha male made an interesting point that hadn’t occurred to me – nuclear power plants need a lot of water for cooling. So could tunnels of practical size, and the enclosed nature of the underground plant generally, cope with this waste heat disposal? Perhaps the heat could be put to good use?

    Not sure if there’s a single topic to be off-topic from in this discussion; but the above seems generally in keeping with the energy theme, and I wonder what any experts think of the idea of nuclear power stations built deep underground, e.g. 10,000′ down in basement rock.

  • The Almighty Bob

    Man-made geothermal (of a type), John? Build it near a subduction zone, and it’d recycle itself, too…

  • Ijon Tichy

    Personally, I’d convert it into glass and drop it into the ocean, but the magical thinkers would have me hung, drawn and quartered for that. So you could be ridiculously safe and put the glass in a stainless steel container, surround that with stabiliser material, surround that with a thin casing made out of material that is corrosion-resistant, surround that with overpack for added stability, surround that with a thin sleeve for structural support, surround that with water-expanding backfill which is the last line of defence, and then bury the entire package in geologically-stable rock with little or no groundwater flow. But before I’d do anything like that I’d simply store it above ground, because the stuff is so damned valuable (think recycling!).

    In terms of waste and safety, there’s some interesting comparisons you can make. A typical nuclear power plant generates a coffee-table-sized chunk of high-level nuclear waste every year. This is billions of times smaller than the waste that comes from a coal power plant with similar power output. And unlike nuclear waste, coal waste kills people every day of every year. Each year you run a single large coal power plant, 75 people die because of air pollution, and a similar number die eventually because of radon emissions and the release of chemical carcinogens into the environment. Nuclear is several orders of magnitude less deadly than coal, and about as safe as wind or hydro.

  • Lab Lemming

    >4) Thorium is three to four times more abundant than uranium, and can also be used as a nuclear fuel.

    This is a perfect example of a statistic that is both technically true and practically irrelevant. I just might write a blog entry just to explain why…

    Also, glass devitrifies in the ocean. You’re much better of with a thermodynamically stable crystalline wasteform, like synroc.

  • Ijon Tichy

    LL: Yes, synroc, by all means, let’s take advantage of advanced ceramics technology (a good example of “down under” ingenuity). Looking forward to your blog entry about thorium.

  • String Theorist

    Hi Sean, Hope you are not going to cave under all the flak you have been getting recently from Peter Woit and co. at his blog. I won’t say anything more about Peter because it has to do with his insufferable (online) personality and constant mischaracterizations of people (and science).

    This blog is excellent as it stands. The line between allowing freedom of speech and allowing anarchy lies to some extent in the eye of the beholder, but it is CERTAINLY not a unanimously accepted truth that you have crossed it. So please blog when you can.


  • George

    Put the radioactive waste back where it came from originally.

  • Lab Lemming

    Everything you ever wanted to know about thorium / uranium ratios:

  • Count Iblis

    They are building a thorium reactor in India

    India unveiled before the international commuity Thursday its revolutionary design of ‘A Thorium Breeder Reactor’ that can produce 600 MW of electricity for two years ‘with no refuelling and practically no control manoeuvres.’

    Designed by scientists of the Mumbai-based Bhabha Atomic Research Centre, the ATBR is claimed to be far more economical and safer than any power reactor in the world.

    Most significantly for India, ATBR does not require natural or enriched uranium which the country is finding difficult to import. It uses thorium — which India has in plenty — and only requires plutonium as ‘seed’ to ignite the reactor core initially.

    Eventually, the ATBR can run entirely with thorium and fissile uranium-233 bred inside the reactor (or obtained externally by converting fertile thorium into fissile Uranium-233 by neutron bombardment).

  • Peter Woit

    “String Theorist”

    The problem I’m complaining about isn’t anarchy, it’s juvenile and unprofessional behavior like yours.

    If I were a string theorist, I’d be rather upset that a colleague was doing this kind of thing anonymously and signing themselves as “string theorist”. You might want to think a bit about what this kind of behavior does for how people perceive your field.

  • ST

    Peter, first, there is a case to be made that your visceral dislike for string theory and the malice, organization and relentlessness with which you try to see it dead cannot BY FAR be explained by a purely scientific motive. Even if one considers string theory as merely a toy model where UV complete theories can be made some sense of, it has more merit than you claim – at the very least it is a useful source of insights.

    So I am not sure you can legitimately make a demand for disentangling the personal from the scientific – at least not the way YOU attack string theory. I meant what I said about your mischarecterizations of people etc. You say it is a personal attack, but I think I am just making a relevant comment. I am not trying to be obnoxious, but the reality of the situation as I see it forces me to be!

    Finally, you will have the moral high ground to talk on “unprofessional behavior” when you clean up the “juvenile” attacks against string theory defenders on YOUR blog. Go do that, and we will talk then.

  • Julianne

    Can we all go back to being excellent to each other now?

  • Peter Woit


    I’ll resist the temptation to respond to “string theorist”, whose behavior anyway speaks for itself, whoever he is. In return, please do me a favor and think a bit about whether allowing this kind of anonymous personal attack on your blog is a good idea.

  • Eric

    Please get off your holier-than-thou attitude. As ST pointed out, YOU are largely responsible for the visceral nature that the discussion of the pros and cons have string theory in the public arena has taken.

  • Lab Lemming

    Count Iblis:
    “Most significantly for India, ATBR does not require natural or enriched uranium which the country is finding difficult to import.”

    Much of India’s domestic uranium production goes into its weapons program, so other countries are reticent to sell them more of the stuff.

    India is in the rather unique position of having poor U resources, Decent Th supplied as a byproduct of heavy mineral sand mining, and a military which is trying to build lots of bombs.

    If they were to dismantle their military program, open up to inspection, and comply with the relevant non-proliferation treaties, then they could import uranium at market prices, and the thorium reactor would probably become uneconomcial. As it is, the need to build Th reactors is just another one of the many hidden costs of building nuclear weapons.

  • Jennifer West

    Thanks Eric, I was going to say that. Also, I wish this Peter person who stop trying to boss people into policing the comments. If you don’t like the commenters on CV, then go away. I don’t always like commenters, no matter what darling blog I’m visiting, but I do not try to ethically browbeat blog owners (while behaving without a moral in sight myself) into making the commenters I don’t like get banned.

    This is what the internets is all about people. If you cannot take the heat, get out of the kitchen. If people continue to behave idiotically, then treat them like trolls. And now, I shall take my own advice and shut up, and begin to behave excellently.

    These pieces of music are really beautiful. Duke is a master, I do agree, and I cannot understand jazz almost all of the time, I am alternately confused and jarred by his notes, and then quickly soothed by some beautiful melody he plays, am ultimately more soothed and amazed than jarred and confused. He’s great. Visually, the way his hands move on the keyboard is amazing. Thanks for the embeds Sean, and have a great time in the South Pacific, recovering your tan, er, I mean, mental health. (In all honesty, good luck getting the papers out as quickly as possible!)

  • Bemused Observer

    It is truly sad that economists of all people are now using string theory as a metaphor for bad science.

    Seriously, the lack of progress – 30 years and still not one testable prediction – is damaging the reputation of physics.

    You guys need to come up with some testable predictions or funding for high energy physics is going to go to zero.

  • krishna

    Lab Lemming,
    Sure, and we indians will greet our enemies with garlands and flowers when they come to kill us. India is not the country that has ~10,000 nukes in its stockpile. There is a cartel (the “Nuclear Suppliers Group”) which controls access to uranium in the world, and the only way India can have nuclear power with minimal reliance on the cartel is to develop a thorium based fuel cycle. Which would you prefer: India burning huge amounts of coal and driving up oil prices by competing for resources in the middle east, or being relatively less reliant on oil and coal through nuclear power?

  • djm

    Krishna, I’m sure they aren’t the only two choices India has. I think Lab Lemming mentioned at least one more…

  • Count Iblis

    Lab Lemming,

    Suppose India has one thousand of 200 kiloton fission bombs (some may be the detonators of thermonuclear devices, we should only count the yields of the fission devices). Then, if you do the math, you find that the total energy yield would only let you operate a single 1000 megawatt powerplant for 30 years.

  • anonymous

    For all those who have seen Peter Woit’s recent post about this blog, you should know what kind of censorship he really advocates. He doesn’t want people to anonymously attack him or other scientists, but he allows commenters on his own blog to anonymously attack non-scientists, as if there were a moral difference (see recent anonymous attacks on Christopher Hitchens in his comments section).

    So his ideas about comment moderation are confused in theory …
    How about in practice? Well, when I made a comment pointing out the double standard mentioned above, in a way that was not inappropriate or rude, Mr. Woit applied his enlightened principles of censorship by moderating my comment out of existence. Sean, don’t change!

  • Peter Woit

    The comment that “anonymous” is complaining was censored by me was posted here:

    and my response to it is here:

    What happened in this case was that the comment was initially identified by the WordPress spam filter as spam, so not immediately posted. When I checked the spam queue that day and found it, I dug it out, posted it and responded to it. It seems that “anonymous” couldn’t even be bothered to actually read the comment thread in question before posting accusations attacking me here. If “anonymous” were using their real name, they might find this embarrassing and it might do some damage to their reputation. But, hey, when you”re “anonymous”, that’s something you never have to worry about!

  • Sean

    Although I did link to a potpourri of different topics above, none of them involved the endlessly fascinating subject of blog etiquette. So let’s just leave that subject for some other time, okay?

  • Chevalier

    LL, I don’t get that people are still arguing for countries to open up their military programs to inspection. After what happened the last time a nation did that, aren’t people in the US embarrassed to ask for it again?

    “Richard Butler…had known of and co-operated with a US electronic eavesdropping operation that allowed intelligence agents to monitor military communications in Iraq. This was confirmed by UNSCOM insider Rod Barton on Australian television in February 2005. This intelligence was used to target US air attacks on Iraq.”

  • Count Iblis

    So, even if string theory is “not even wrong”, you still need to know about it to be able to make sense of the blogosphere. :)

  • Lab Lemming

    Count Iblis,
    comparing the energy released from a bomb with a reactor is misleading, as it neglects the energy consumed in making bombs, which is considerable.

    It is also irrelevant to my point, which was this:

    India, due to a shortage of uranium, has no economic uranium mines. That is, there are no places where the total cost of finding, digging up, and refining uranium is less than the current market price.

    Due to their weapons program, India mines uneconomic uranium for bombs. It can do this because bombmaking is not an economic activity, so they expect to lose money.

    Because they make bombs, most uranium producing countries will not sell uranium to India for any purpose, for fear that it might end up getting used for military applications.

    Therefore, the price of uranium in India is artificially high. It is this unusually high local uranium price that makes thorium reactors economic there, but not in the open market.

    Krishna, I do believe that thorium reactors are preferable to coal, especially in countries like India with lax emissions laws.

    As for the wisdom of nuclear weapons, it is my personal opinion that India should stop making atomic bombs and instead concentrate on weaponizing Harbhajan Singh. In the case of an attack by Pakistan or China, India could fire the off-break spinner into Beijing or Islamabad, where he can personally bitch-slap whoever ordered the attack.

  • Ijon Tichy

    This [i.e. the fact that thorium is four times more abundant than uranium — I.T.] is a perfect example of a statistic that is both technically true and practically irrelevant.

    L.L., you are wrong in one sense, and right in another sense. I have two explanations: long-winded and short.

    Long-Winded Explanation:

    As you explained in your nice blog post, the chemical properties of thorium (Th) are such that it is more difficult for natural geological processes to concentrate it than they can concentrate uranium (U). How much more difficult? One obvious way is to compare the bulk Th:U ratio to the ratio of Th reserves to U reserves. Estimates of Th reserves are sketchy: quite a few countries do not report, and there has been even less exploration of Th than of U. I have seen Th reserves estimates ranging from between 1.2 million tons and 2.5 million tons (these are only reasonably assured reserves). Give Th the intensity of exploration that U has enjoyed, and I do not think it unreasonable to expect that the amount of Th reserves would be similar to the amount of U reserves. So perhaps 4 times more difficult, perhaps more. In any case, on the question of how much thorium we can extract out of the ground, you are wrong that the bulk Th:U ratio is irrelevant: it is relevant precisely because of the relative difficulty of finding rich deposits of Th in the crust. Imagine if the bulk ratio was the other way around, i.e. U/Th was 4. Then the Th boosters would have much less of a case.

    Fortunately, the case for Th does not rest entirely on the bulk Th:U ratio. In fact, most of the case rests on something else, something further down the ore-electricity line. It’s something I already mentioned in an earlier post: only 0.7% of the U extracted from the ground is used to generate electricity (i.e. the U-235 isotope), while in a Th reactor, virtually all of the Th is usable (after converting to U-233 via a cheap, efficient process of neutron bombardment). Since the output energies per atomic unit of mass are similar for both sets of fission reactions, we just need to compare 100% to 0.7% to get a rough idea of how much more “energy-rich” a given mass of Th is to a given mass of U: at least two orders of magnitude. So on the question of how much energy you can extract from the world’s supply of thorium, you are right: the bulk Th:U ratio is not very relevant, because it is a significand issue, and we are concerned mostly with the exponent.

    Short Explanation

    Current thorium reserves are probably not much less than uranium reserves. All of the thorium, compared to only 0.7% of the uranium, can be used in the energy generation process. Notice the two orders of magnitude difference: that gives us a good amount to play with on the relatively uncertain issue of thorium reserves.

  • Lab Lemming

    “Give Th the intensity of exploration that U has enjoyed”

    e.g. 2 years? The reason I got hired was that all the uranium geologists with work experience are now in their late 60’s or older. Nobody has looked for U since Three Mile Island flattened western demand when I was 6 years old.

    Also, Monazite deposits occur in a subset of titanium/zirconium heavy sands deposits, which have been in keen demand ever since we started building rockets and gave up lead paint. So the accidental byproduct exploration for Th has actually been greater than for U, as Th deposits are cogenetic with other valuable minerals, while high grade U isn’t.

    As for the ore grade, consider the Western Australia mineral sands, which are one of the more Th-rich deposits. The Th here has been studied extensively for radiological hazard work resulting from dust inhalation. The mineral sands (zircon+ilmenite+rutile+monazite) generally grade 10%, of which 2% is monazite. The monazite there has a Th content of around 5%. So the Th content for the deposit is 5% of 2% of 10%, or 100ppm. (numbers from )

    100ppm of 235U requires a total U grade of 13888pmm, or around 1.4%. This is a few times higher than most producing Australian mines. Canadian mines are much higher grade, however- generally around 20%U, or 1440ppm 235U.

    There do exist some obscure high Th rocks (high being a percent or two)- one happens to be in the roadcut of a major US freeway (to find which one, start driving around with a scintillometer in your car). But they are small, rare, poorly understood, and not easy to look for.

    But the main advantage of U-based reactors has nothing to do with geology- it is that they are available now- the technology is mature. Th may be competitive in a few decades, but by that time, renewables will probably be cheaper. Wind power is already cheaper than nuclear- it just has stability/storage issues.

    I’m all for burning today’s Th byproduct in a reactor- it makes a lot more sense than disposing of it as radioactive waste- but I think that assuming that this technology can support civilization is a bit premature. Feel free to prove me wrong with a superior reactor design and exploration plan.

  • Erik

    Not to long ago it was considered a sin to let any food go to waste. Now we burn food in car engines while children in other countries starve to death.

    It’s sad that logical reasoning is no longer used when discussing energy issues. The fear of nuclear energy is so ingrained that it is not considered even when: *environmental disaster is looming
    *people starve when alternative energy is used
    *the US economy is bleeding dollars to oil producing dictatorships

    Technically, with nuclear energy, it wouldn’t even be to difficult to produce carbon neutral fuels for use in vehicles.

  • Ijon Tichy

    But the main advantage of U-based reactors has nothing to do with geology- it is that they are available now- the technology is mature.

    Yes, actually, I agree with you. I’m not advocating using thorium-based reactors right now, although we would be stark raving mad not to immediately start building some experimental reactors, given the obviously great potential of thorium as a source of energy.

    Wind power is already cheaper than nuclear…

    That is a biased and probably wrong statement. Estimating costs for various forms of power is not an exact science. Costs will vary depending on location and time, on what you count (external costs like pollution?) and what you don’t count (what about subsidies?). The best you can come up with is a range of estimates. For your statement to be true, you would have to take the lower end of the cost estimates for wind, and compare it to the higher end of the cost estimates for nuclear: that is unfair and hence biased. I say you are probably wrong, because the lower-end estimate for nuclear is a bit cheaper than the lower-end estimate for wind, the higher-end estimate for wind is significantly more expensive than the higher-end estimate for nuclear, but nevertheless there is significant overlap between the two. A fair statement would be that the average costs for wind and nuclear are in the same ballpark, but it is a bit more likely that nuclear is cheaper than wind rather than vice versa.

    Feel free to prove me wrong with a superior reactor design and exploration plan.

    Well I think the superior reactor design for thorium is already well-known: molten-salt reactors, and in particular, the liquid-fluoride variety. An experimental reactor based on this design was actually built and run successfully at the Oak Ridge National Laboratory in the USA, over 40 years ago, and you can read about that project here.

  • Count Iblis

    Lab Lemming, I see! But the new deal with the US and the IAEA will change the situation.

    I agree with Ijon Tichy and Erik on nuclear power. The history of the SNR-300 reactor shows that bad decisions were made in the past which took away some of the options we could have had today.

    It is feasible to produce a large fraction of all our energy needs from nuclear energy and the remaining part from renewable energy sources, such as wind power and geothermal energy. We also need to store energy, e.g. by producing hydrogen.

    It is also possible to build “power islands”. You can use wind power to pump out seawater and by letting it flow back in, you can generate power at any time of the day, regardless of whether there is any wind or not.

  • R Senic

    Sorry I am a week late to the party, Ijon & Lab Lemming. Jeremy Whitlock’s excellent Canadian Nuclear FAQ is worth an examination, perhaps most relevantly:


    ( is also interesting and has a section on Thorium)

    The Canadians, South Koreans and Indians have collaborated in various ways over the years (the Canada-India relationship is, uh, complicated, not least by the fact that Canada’s completely civilian nuclear engineering community sometimes seems congenitally unwilling to keep politically embarassing or militarily sensitive secrets (“they leak like a calandria”). CANFLEX (AECL and KAERI), DUPIC (AECL, KAERI and KNFL), once-through cycles with on-power managed piles comprising 232Th bearing sand bundles (“OTT” from AECL and BARC) and the increasing number of Korean “reburn” PWR-PHWR (AECL, KHNP-Kepco, KNFL) sites are among the results.

    These developments are described on the FAQ site and Whitlock himself is an avid emailer, in case you spot errors or have questions, as noted at the bottom of the main page.


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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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