Do you think Hollywood is going to turn over the rights to let you copy whatever you want of their stuff for a few paltry million $ that this would bring in?!?! Even if every single internet user in the United States paid $5 (much less the pathetic $1 you're suggesting), that would only be about $775 million.
Paltry? Umm... in December 2006 there were 82.5 million active broadband lines in the U.S. (see: Networked Nation: Broadband In America 2007). The proposal is $5 per month per broadband customer. This is $5 billion a year, even at December 2006 adoption rates. It will climb higher in years to come as broadband penetration increases.
For comparison this is almost half of the recording industry's revenues from 2006. And this would be essentially all profit. For this kind of gift (if they could get it) the public should demand the sky in freedom to do whatever it likes with the recording industry's products. Even a $1 fee would likely more than double its annual profits.
This proposal should be no surprise to anyone. The recording industry has become accustomed to having the government impose special taxes to provide it with revenue under the theory that these taxes compensate it for (unproved) lost sales through piracy.
See: USC Title 17, 1008 "Royalty Payments". This is a tax imposed on music CD-Rs, digital audio tapes, stand-alone CD recorders, and digital audio recorders. In 1998 the RIAA tried, but failed, to get special taxes imposed on MP3 players.
Notice that these are taxes on *digital* devices. Analog technology (blank vinyl disks and vinyl recording devices, analog tape and recorders) never had these levies, and yet the industry survived just fine.
At the same time the industry has been obtaining access to tax revenues (originally under the theory that this was a trade-off for more liberal copyright restrictions) it has also been seeking, and getting, increasingly draconian revisions of copyright law.
In all, the recording industry has had some success in using computer technology as a scare tactic to stampede congress into granting it immense new assets at the public's expense. Despite its great success in this copyright land rush, it is still crying poverty, hoping for even greater gains. Its lots easier than running a successful, adaptable business. The MP3 episode shows though, that these attempts can be resisted.
Everything you say is true, but is not relevant to his definition of fairness... Not to say you aren't right, but he's a mathematician and not a politician...
Quite so, and to get a publication out of the issue he has to offer a new and more complicated method than any of the historical ones. An excellent study of this issue was prepared by the Congression Research Service six years ago.
The upshot of this report is that the current method (the Hill method) is one of the best ones ever implemented or seriously proposed. But the triviality of this issue can be judged from the fact that this report shows that if the Hill method were replaced by the simplest and earliest proposed method (the Hamilton-Vinton ranked fractions method) only one single seat in the 2001 House would have changed hands.
Given the extreme favoritism to tiny states that the current Senate and Presidential representation schemes provide (the latter through the Electoral College), it is not at all evident that there is a problem here in need of fixing.
Wonderful deal, isn't it? Iran only has to build expensive reactors, and buy the fuel from the US (or whoever provides it) which will of course be sold at a profit (so it's not exactly a huge concession on the provider's part)
That'd work right until the provider decides it doesn't like something going on and says "No more fuel for you!".
Um. Do you realize that enriched reactor fuel is a competitive market, with at least three suppliers competing for business: the USEC (in the United States), URENCO (a western European consortium), and Russia. SWUs (separative work units), the standard measurement of enrichment, are an industrial commodity which can be purchased (you supply the uranium) for a small fraction of what Iran's domestic enrichment would cost. Iran is not saving itself from extortion by greedy capitalists. It is incurring huge financial, and potentially huge political costs, to make something that it can buy cheaply and easily from numerous sources (for legitimate commercial use, that is). The market for enriched uranium is much more competitive that is the market for, say, oil.
China is entering this business and Australia is currently hot to get into it also. Iran has no shortage of eager potential suppliers, and in fact has one right now: Russia! In case you missed it, Russia shipped Iran its first fuel loading this week. As an active geopolitical rival to the U.S., and ever eager to build its power and influence on its southern border, Russia is certain to continue to ignore any U.S. effort to deny Iran uranium fuel for its domestic power plants.
Whatever the reason Iran has for pursuing domestic enrichment, it is not to save money or to safeguard access to low enriched uranium for commercial use.
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature... Mt. Saint Helens... Krakatoa... Lake Nyos... And which of these are examples of the supposed megaton range methane gas explosions? Why... none of them. Sorry, unrelated geophysical events don't provide any precedent for the proposed mechanism. The notion seems a bit difficult to buy into - the explosive limits for methane in air is usually quoted at 5-15% by volume, to make a mammoth blast you would need to establish this specific concentration range with millions of tons of methane, and have it ignited at the proper time. How does this happen geophysically? Any actual examples?
2. That there was swamp land in the center of the Tunguska caldera. This is a typical place for methane to build up. But... millions of tons? Capable of sudden release? People should be finding commercial exploitable methane gas deposits in the surface strata of swamps I should think.
3. The directions in which the trees had been knocked down indicated two discrete blast points some distance from one another. If this was observed, a twin asteroid would be a reasonable explanation (recent probe and radar evidence shows asteroids to frequently consist of loosely bound multiple bodies).
4. There were odd glowing clouds seen over the area in the nights leading up to the explosion which could be explained by methane collecting in the sky. Reports on the Tunguska event I have seen report glowing clouds in the sky afterward, not before.
5. No impact crater was found. Only the very rare iron asteroids are strong enough to make ground impact in this size range. The far more common stony bodies will fragment and explode in the air. This is a complete red herring.
6. No meteorite was found. This is a red herring like 5. It exploded high in the air. The extraterrestrial particles found are the meteorite.
The whole notion that this is an unprecedented event that requires alternate explanation is utterly wrong. Atmospheric explosions of extraterrestial bodies are regularly documented events. The Defense Support Program (DSP) has monitored atmospheric explosions since the 1960s and has found Hiroshima-sized (16 kt) events occurring about once a year. A simple statistical distribution permits calculating the frequency of larger events, a 10 Mt event is expected once very 120 years. See:
an item about this in the Acoustical Society of America's newsletter. This being the case, there is really no anomaly here to be "explained away". Bolide explosions are a regular occurrence and we should see some in the megaton range in the historical record - most of course occur over open oceans and have had few witnesses and left no evidence.
Living things are, in general, very competitive, and very effective competitors. Otherwise, they wouldn't still be here. So the odds that a new abiogenesis event, if one occurred, would produce a lifeform that would actually be viable in the face of a billion years of evolution by the competition are, I think, remote.
...
Finally, while it is true that many lab techniques are specific to detecting conventional terrestrial life, others are not. So, unless this non-conventional life is *restricted* to some remote environment - which conventional life certainly is not, so this again seems unlikely - we would be expected to have seen it.
There are some exotic coincidences which might allow for this to be true - maybe this exotic life looks just like a bacterium under the microscope, but for whatever reason cannot be cultured at all. Maybe it can't live on sugar - maybe it requires some other exotic organic nutrient which is found out in the wild but no-one has thought to add to culture medium. All possible, but also all unlikely.
The undercurrent of thinking in the above (which is the historically dominant one addressed in the opening paragraphs of the article) could be summarized as: "If a fundamentally distinct form of life existed, we should of seen it by now, since science has by now pretty thoroughly explored all of the Earth's environments, and its organisms. So our current status of non-observation is very strong evidence of non-existence."
If this premise of thorough characterization of the biosphere is correct, then we shouldn't have had any radical new discoveries about the diversity of conventional life in, say, the last 30 years either.
In fact there have been quite a number of truly astonishing discoveries of this nature. Most prominent was the discovery of the third kingdom of life on Earth, the Archaea, in 1977 by Carl Woese. The Archaea is a branch of life as different from the other two branches (Bacteria and Eukarya) as they are from each other. Yet science, well advanced by any standard at that point, had failed to notice it. See, for example Virginia Morell's write-up on the Woeseian revolution in Science, 2 May 1997, Vol. 276. no. 5313, pp. 699 - 702, or Carl Woese.
Another example concerns the very extensively studied kingdom of Bacteria. It stands to reason that by the later 1990s the bacteria in any common soil sample must have been pretty well characterized, right? After all, these are ideal subjects of study, readily available, conveniently small but not too small for study. Microbiologists had been culturing and classifying them for a few centuries by then. Except that when examinations of how many bacteria could be visually counted in a typical sample was compared to the number that could be cultured, it turned out that less than 1% of the bacteria could be grown for study. And when it became possible to do mass screening of DNA fragments in the environment it turned that less than 1% of the fragments from a common soil belonged to organisms known to science. So it transpired that biology was familiar only with the bacteria that could be easily grown in the lab, which turns out to be hardly any of them. See for example: A Molecular View of Microbial Diversity and the Biosphere by Norman R. Pace in the same issue of Science above (pp. 734 - 740).
Other examples. It was discovered in 1977 that pelagic bacteria, previously unnoticed, accounted for most of the biosphere mass in the oceans, and most of its biolgical activity. Here we had the largest component of the entire biosphere of Earth escaping notice! Similarly, the most prevalent organisms in the oceans turns out to be viruses (but are lower in mass since they are much smaller), yet these escaped notice until 1989. See: "Microbes, Molecules, and Marine Ecosystems" by Farooq Azam and Alexandra Z. Worden in Science 12 March 2004: Vol. 303. no. 5664, pp. 1622 - 1624.
This is true, but it's only because it's a binary solution set. Until or unless SETI finds a transmission, it will have made no progress in finding one, only in not finding one.
Progress in not finding one is very important progress in itself. SETI in the only means we have of gaining understanding of the Fermi Paradox: the fact we know intelligent life is possible, and that there are no identifiable physical limits that prevent intelligent life from making its presence not only detectable but ubiquitous. The absence of detectable signatures of intelligent (and technological, an important qualification) life tells us something fundamental about the Universe, the nature of intelligence, and ourselves. What exactly it tells us remains for us to figure out.
It is a foolish and unscientific tendency to view negative evidence as being worthless. If we have a reason to believe that something should or could exist, we should definitely devote effort to looking for it - be it magnetic monopoles, nanobacteria, cosmic strings, deviations from special or general relativity, etc. We can only establish rarity, or absence, by actually looking for the evidence. An extensive and systematic SETI program, spanning centuries, that never turns up anything would provide us with powerful constraints on the limits of intelligent life in the Universe.
This whole post is fictional history. Some statements in it are factual but the story, as presented, is false.
Japan was actually getting serious about the possibility of a fission bomb, Germany wasn't. Some historians think it was because Germany's racial doctrine was so aggressively disparaging of 'Jewish' physics, and so their research and funding ended up being steered in other directions. Japan had physicists who weren't afraid to use Einstein's or other Jewish physicists work in their own papers.
This a confused mishmash of half-facts and outright falsehoods. Nazi purges of academia had lost them a good portion of their best physicists who were either Jewish, or communists, or were non-Germans who simply had had enough of the regime. But Germany was the world center of physics at the time and they still had many, many highly competent physicists. Nazi doctrines had no influence at all in the practice of science by scientists. See Alan Beyerchen's excellent "Scientists Under Hitler".
In September 1940, the Japanese Army controlled Institute of Physical and Chemical Research, or Rikken, was assigned a preliminary project. In 1942, the Japanese Navy began also (somewhat independently of the Army) working on a Uranium based fission device. The project was called F-Go {or sometimes just No. F, for fission].
This much about Japan's effort at least is more or less correct, although the Japanese Army did not control the Riken (correct spelling, Rikken is a Dutch card game). The two research programs, NI-Go and F-Go, together constituted a tiny effort by a nation short on scientists and advanced industry. The total peak employment of both programs combined, including assigned military officers was 55 people, and the total amount of money appropriated to the effort was $350,000. The U.S. effort employed 2000 times as many people, and spent 5000 times as much money. In all of Japan there were only 30 active physicists, far too few to staff a serious fission effort. See Walter E. Grunden, "Secret Weapons and World War II: Japan in the Shadow of Big Science", University Press of Kansas, 2005.
This was located at Kyoto, and was actually the chief reason why Kyoto was added to the list of potential military targets for the U.S. bombs,...
This is simple fantasy. No such consideration ever came up in the work of the Target Committee.
...and the Japanese were probably still four or more years from having a bomb by the end of the war.
True, though a vast understatement. The Japanese project had only prepared a few grams of ordinary uranium metal, had only a few hundred kilograms of crude uranium compounds on hand, and had not enriched even a microgram of uranium above natural levels. Really, the program had no results at all, and thus could hardly be said to have even truly begun.
A Japanese plant, concealed in Hungnam, now part of North Korea, may have been the source of heavy water subsequently used by the USSR for its own bomb research. There are reports the Soviet Union continued to run that plant and collected the output every other month by submarine, and it alone may have shaved a year or more off the USSR's development time.
All of the above is fantasy.
In May 1945, a German submarine which surrendered to US forces , was found to be carrying over 500 kg. of Uranium oxide destined for Japan. The oxide contained about 3.5 kilograms of isotope U-235. While not enough to make a bomb, that was a sizable fraction of one.
A bit like evaluating a pile of iron ore in terms of the number of jet engines you could potentially make out of it. That such a small quantity of uranium compound was considered significant by Japan indicates how short of resources they were.
After the Japanese surrender, the occupying US Army found five cyclotrons which were capable of separating fissionable material from ordinary uranium.
The U.S. Army didn't "find" them. They weren't secret
The basic idea is to create a small fission (not fusion) explosion using magnetic compression. Nuclear weapons use chemical explosives to create an implosion, and during the implosion the fissionable material is compressed hard enough to get a 1.5x to (maybe) 2x density increase. With magnetic compression, a small pellet can be compressed hard enough to get a 10x density increase. This allows smaller explosions, around 50 gigajoules instead of the 20 terajoules of a fission bomb. They want to use curium or californium as the fuel, rather than plutonium.
The experimental work (they compressed an aluminum cylinder with a big magnet at Sandia) was done back in 2002. This isn't really under active development... It's not a totally unreasonable idea, but it would be a huge job to make it work.
Good post.
To expand upon it a bit, I will observe that actual pressures and compressions demonstrated so far are maybe a couple of orders of magnitude below what is needed to achieve 10-fold compression of fissile material. They demonstrated pressures of 2.4 megabars (atmospheres) and roughly two-fold compression in aluminum, performance generally similar to what high explosive implosion systems have produced for over 50 years. Despite decades of work, HE implosion has never been scaled to the pressures or compressions postulated for this. See: APS and
AIP pages on this.
Now, their ace-on-the-hole is that they can achieve isentropic compression (i.e. optimal compression, without heating) explosive systems cannot, but even so they aren't in the ball-park with this, only looking at it with binoculars. And the Z-machine is a huge immobile installation. How to convert a grossly souped up version of it to practical flight-ready hardware would be a staggering task.
So this is in the same league as commercial fusion power. A concept that has some grounding in reality, but possibly one forever beyond practicality, and certainly beyond the working career of any living engineer.
Hey, it could happen. It's just hard to remember, as for the last 16 years we've had no one but Clinton and Bush. I remember the first time I really paid attention to Bush on TV, after he won his first nomination. I remember thinking, "holy cow, the lefties are going to hate this guy every bit as much as we righties hate Clinton." And I was right. But it doesn't have to be that way.
So far, so good.
Of course it would be with Hillary. With Obama, I think it would just be a general disgust at his incompetence, like with Carter. The key is whether the person will polarize or unite the center. Someone like Fred Thompson, I think would likely win them over, the way Reagan did. If Newt runs, it's hard to say. He eventually lost the center to Clinton as house speaker, but first he masterminded the Contract with America and won Congress for the Republicans by winning them over. But if he had the machinery of a presidential campaign with which to respond and react to the MSM, who knows?
And now we get content-less denigration of four Democrats, and praise for three Republicans (plus a quick dig at the "main stream media").
This type of party-line thinking is just exactly why it currently happens to to "be that way".
> How much is the contribution of gravitation (weight->pressure->heat) to geothermal activity? I would have guessed it exceeded that of radioactivity.
A couple of billion years ago, you'd be right, but the heat inside the earth today is sustained by radioactive decay. There's also some heating due to tidal effects as the planet gets tugged on by the sun and moon as it rotates. Heat from solar radiation doesn't really penetrate, but the warmer the ocean and the atmosphere are, the less heat escapes from the interior.
The capsule summary:
* A variety of sources heated the Earth immediately during formation: gravitational collapse, adiabatic compression, and short lived radioactivities that quickly disappeared. Gravitational collapse may not have contributed much heat to the inner Earth because it could have been mostly dissipated during accretion, but this is uncertain.
* Today decay of U, Th and K produce something like 40-75% of the observed total heat flux from the Earth. Solidification of the core (heat of fusion) produces about 10%. Cooling of the ancient heat deposited in Earth's formation is 15-50% of the flux.
* So - there is a lot of uncertainty here. It is most likely that radioactive decay dominates over simple cooling of ancient heat today, but this is uncertain. If one includes core solidification as a form of ancient heat (it is latent heat of formation) then the likelihood of radioactive decay dominance diminishes and it becomes possible that ancient heat still dominates today.
If there's one thing that Slashdot has taught me: never underestimate the power of a mob of self-righteous "environmentalists" with entirely too much money and free time on their hands.
Ah yes, those ultra-rich, super-powerful environmentalists that have those impoverished multi-national corporations everywhere on the ropes! As you say, it must just be that they have tremendous amounts of free time to waste. It is not as if environmental degradation has ever been a problem anywhere.
Still - it might be nice to thoroughly explore Mars first and determine conclusively whether it has a native biosphere or not, before utterly destroying its natural climate. We might learn something, and some of that knowledge could even turn a buck! Making money is, after all, what is really important here (just keep it out of the hands of those environmentalist plutocrats!).
Monsanto was on there at #27. Monsanto are the people that... have engineered plants that are sterile and can't be replanted so people have to keep buying new seeds...
Just a reality check on this particular complaint:
Most commercial farmers (at least in the industrialized world) plant hybrid seeds (technically F1 hybrids), and have for the better part of a century. F1 hybrids aren't sterile, but they also can't be replanted because the desirable hybrid traits are lost in the F2 generation. Not being able (in a practical sense) to save seed and replant is nothing new, its classical plant breeding. A large majority of commercial farmers don't save seed, or want to, they repurchase each season as just one of many expenses involved in the business of farming.
anything to stop the people from acting responsibly?
Unfortunately the global warming problem is so severe that even a magic wand that shuts off all carbon dioxide production worldwide today, and stripped away all CO2 released over the last 7 years, wouldn't stop continued warming for most of the next century (though it would markedly reduce it). See page 13 of: the IPCC Working Group I Fourth Assessment Report Summary for Policymakers. Even extremely optimistic scenarios for reducing CO2 release lead to warming over the next century three of more times greater than the "magic wand" solution.
Although acting responsibly is certainly necessary, the situation has reached the point where even immediate dramatic responsible action (not yet in evidence, sadly) will not avoid severe climate change in coming decades and centuries. To reduce the scale of the developing disaster additional measures may be necessary.
Crutzen's stratospheric sulfur injection proposal has the advantage that natural experiments have already proven that it works. The eruption of Mt. Pinatubo in 1991 was a recent example.
A recent report on this in Science was:
Science 20 October 2006:
Vol. 314. no. 5798, pp. 452 - 454, "A Combined Mitigation/Geoengineering
Approach to Climate Stabilization"
T. M. L. Wigley
Summarizing Wigley's findings, Richard A. Kerr in the same issue stated:
Pulling off a "human volcano" to counteract global warming would take some
wherewithal. Pinatubo put up 10 million tons of sulfur, most of which fell
out of the stratosphere within 2 or 3 years. So humans looking to cool the
greenhouse by stratospheric shading would have to send millions of tons of
sulfur tens of kilometers into the air every year, perhaps century after
century, in order to renew the continually depleted shield of haze. The
resulting acid rain would be minor compared to current levels, say
proponents. People have discussed delivery methods from balloons, big guns,
and giant planes. To ease the burden of lifting megaton masses, the late
Edward Teller--father of the hydrogen bomb and "Star Wars" missile defense
advocate--proposed substituting more efficient reflectors for sulfur,
something metallic and perhaps engineered like tiny retroreflectors.
Daunting practical aspects aside, the latest--although preliminary--climate
modeling hints that shading the globe to counteract greenhouse warming could
actually work. In this issue of Science (p. 452), climate researcher Tom
Wigley of the National Center for Atmospheric Research in Boulder, Colorado,
reports that in a simple, so-called energy-balance model, firing off a
Pinatubo eruption every 2 years or so would be enough to counteract the
projected warming indefinitely. And so far in sophisticated general
circulation models (GCMs), "all the simulations have suggested it would
basically work," says Caldeira, who has run many such simulations. Crutzen,
who has been cooperating on other GCM simulations, agrees. "It's very
tantalizing," he says. "It just looks too good."
Not really. Decay time due to drag for LEO is fairly short. Debris in orbits below 300 km (where ISS lives) falls in less than 30 days. Debris up by the Hubble can stay up for years, but will fall eventually. Here is a chart of orbital decay vs. altitude.
This is correct. At low enough altitudes space debris does not cause a run-away debris scenario. This point was made in the New York Times article - if the Chinese had conducted their test at the ISS orbital altitude there would be no long term problem (just a medium term one for the ISS).
In fact drag automatically clears debris below about 700 km, eventually, but not above that altitude. There was a good article on this a year ago in Science: "Risks in Space from Orbiting Debris" by Liou and Johnson (20 January 2006: Vol. 311. no. 5759, pp. 340 - 341). They published a debris vs altitude chart for 2004, 2104, and 2204 showing that (assuming nothing else is launched into space), the existing debris cloud would be entirely cleared below 400 km in 100 years, and at least reduced below today's density between 400 and 700 km. Above that altitude the density keeps climbing century after century. By far the worst hazard is between 800 km and 1050 km.
This limits the hazard to a certain band of orbital altitudes, a fact not brought out in the news article. It isn't a denial of space by any means, but it is a significant restriction on usable orbits.
Ok, this is odd. Your criticism is spot-on about Fermi, but also shows you didn't read the paper, where he does indeed address (badly) the concepts of self-replicating probes and the like. He just thinks they are a bad idea. Not infeasable, mind you, just a bad idea so nobody would build them. So yes, it's a very naive study, but you do have to do even such papers the credit of reading before saying they don't consider geometric growth.
It's true I hadn't read it, I was having trouble downloading the PDF and went by the Guardian article and the Arxiv abstract. But after having read it, my point is the same - considering a special case (a small fixed number non-replicating of probes launched by just one civilization) fails to address the Fermi Paradox at all.
His major finding is that with a fixed number of probes, n, the time to explore the galaxy is linear in the number of probes (not too surprising, that). So if n is sufficiently small then there won't have been enough time. He prefers a number of about 20 probes/subprobes, but was willing to consider as many as 1800 (which would actually cover the entire galaxy in about its actual age, according to his model). Why these small numbers? Well, you see, these probes are expensive so he assumes that not many would ever be launched. If he had instead assumed a low continuous launch rate of, say, one per thousand years then the entire galaxy would have been explored in 200 million years. So his claim to address the paradox fails even within the limitation of one civilization and non-replicating probes.
He does mention replication but utterly fails to clear the high hurdle I described required to dismiss it. He simply argues it seems like it might be a bad idea to let self-replicating probes loose. Maybe. But then you just keep them at home, and sterilize them (so that they cannot replicate) before letting them go. Then you have a geometrically increasing launch rate of non-replicating probes that would explore the galaxy in about the time it takes to traverse it: one million years at the assumed 0.1 c.
The reasoning above is why I believe the Prime-Directive/Zoo thesis is the most likely Fermi answer. That only requires that one intelligent race, the one that controls our neighbourhood, wishes to hide from us the evidence of ETs. The "we've in a virtual universe" answer also meets that requirement.
This solution does actually address the problem, but it is analogous to the creationist Omphalos argument that God created the world (and universe) 10,000 years ago and fabricated all the evidence to give it an apparent age that was much older. Seems unsatisfying. (Especially since if you accept it then the moment of creation could have been 10 minutes or 10 seconds ago).
Can anyone propose a test to prove that we aren't living in the Matrix?
The study in question does not even address the Fermi Paradox in any meaningful sense, much less "resolve" it. In fact, if this study is being offered as a resolution of the Fermi Paradox then it suggests the researcher does not understand why the Fermi Paradox is a paradox at all.
The fundamental difficulty with any explanation offered for the complete absence (so far) of any sign of other intelligent life in the universe is that the proposed explanation has to be universally valid.
The span of time for colonization, or dispersal of replicating probes, or of building vast telescopically detectable artifacts is so great that even one single exception from any proposed explanation would be capable of generating ubiquitous evidence in a tiny fraction of the life of the Universe.
Simply describing some model for exploration, and then arguing that this model won't do the job says nothing about other models. This study apparently does not consider the geometric growth that occurs with any exploration program that uses some form of replication of explorers, for example. If replication is thought to be impossible then the study would have the high hurdle of convincingly demonstrating this. (The material evidence of life on Earth seems to argue persuasively against it though.)
Arguments that "interstellar travel is impossible" would qualify for explaining why alien artifacts aren't being found locally (but do not address communication signals or telescopically detectable artifacts), but require convincing arguments that this is indeed true. On the contrary, physics does not seem to make this impossible at all, just very costly and slow. Too costly and slow for anyone to bother? Not even one single civilization?
The Fermi Paradox seems to be telling something important about the Universe. If only we knew what it is...
From a quick scan - "Even with aggressive assumptions about biological productivity, we project costs for biodiesel which are two times higher than current petroleum diesel fuel costs".
If that was in 1998, then at should be very feasible with current petrol costs, especially taking into account the added value of removing CO2 from the atmosphere.
Indeed so! The 2006 inflation adjusted price in 1998 was $18 a barrel, last I checked it was three and half times this right now. In fact the average inflation adjusted price over the last 33 years is about double the 1998 price.
If the DOE algae biodiesel cost estimate is correct then it has already been on average a break-even technology for a third of a century.
Both the total world production of oil and the production of oil available for export are peaking about right now. This has been predicted for years:
http://www.energybulletin.net/147.html
and current studies verify this.
Thus the cost of oil is not likely to experience any significant downward trend from now on, ever.
The original article's production estimates are a bit suspect though. The 20,000 gallons of biodiesel per acre they give as the upper range of production is 47 g/square meter a day. The DOE gives a maximum annual production of 50 g/square meter of algae (not biodiesel) a day.
A lethal dose of polonium-210 is an absorbed dose that will deposit about 600 rads (or 600 centigrays, cGy) of internal radiation exposure before it is eliminated from the body. Given its biological half-life of 30 days, this quantity can be calculated at 4 millicuries (4 mCi, 1.5x10^8 Bq) for an 80 kg man. This is only 0.9 micrograms. Not all of an orally administered dose will be absorbed, so the actual amount that would result in lethal poisoning is more than this.
The largest amount of Po-210 that can be purchased in the U.S. without a special license is 500 microcuries. The most abundant readily available commercial source for this is in Staticmaster® Brushes: http://www.2spi.com/catalog/photo/statmaster.shtml which contain 250 microcuries absorbed on a plastic resin. This is 2,500 times the amount in the source from United Nuclear. The Staticmaster replacement element (without the brush) can be bought for $20.
Extracting the polonium from, say, 30 Staticmaster elements would take a bit of skilled chemistry. The elements would need to be dissolved and the polonium freed, and it would then need to be concentrated into a modest amount of palatable material. Handling polonium is tricky, it is volatile and is notorious for its ability to "migrate" around the lab (which may account for the contamination found at various sites which Litvinenko visited).
It should be noted that Aleksandr Litvinenko was poisoned with far more than 4 millicuries. A minimal lethal dose would take more than a week to accumulate enough exposure to cause apparent illness, and lethal levels would take a month or more to accumulate with death following weeks later. Litvinenko became ill within one day (it appears), and was dead just over three weeks later. Given the latency of death from Acute Radiation Syndrome (ARS), he must have accumulated a lethal dose within a day or so. The amount administered was likely dozens of times the lethal level.
One possible explanation for the rapid onset of illness and (for radiation poisoning) quick death is that the radiation-sensitive lining of his gastrointestinal system was destroyed before and during the absorption of the polonium. The gastrointestinal subsyndrome form of ARS is very lethal and kills in about three weeks. The transient concentration of polonium in the GI tissue would have been very high, and even polonium that was not absorbed would irradiate the lining.
I doubt that the 2040 "demonstration power plant" mentioned in the article
equates to a "commercial reactor". Since ITER will produce heat but no electricity, and will be smaller than a commercial scale system by a factor of 10 to 20, the demonstration power plant will presumably be *prototype* of an electricity producing plant,
but not a full-scale commercial system. Commercial availability would be years after that.
The economics of fusion power are, unfortunately, quite depressing. There was a short
article on this in Science, 10 March 2006 (p. 1380). It estimated that
the the capital cost for the blanket-shield alone in a 1 GWe powerplant
"amounts to $1800/kWe of rated capacity--more than nuclear fission
reactor plants cost today". All the other extravagantly high tech
equipment and construction costs are in addition to this. It posits a
total capital cost of $15,000/kWe of plant rating.
Is there any other alternative energy scheme that is seriously proposed
that is *more* expensive than this?
The problem is solely socio-political. It costs more to prepare, obtain, and shepherd through a totally uncertain legal system the required permits for construction than the actual construction itself. Add the decade long lead time to ground-breaking for which interest on capital is charged but not recouped. As icing on our heaping pile of fecal matter pie here, toss in unknown legal liability concerns due to the unresolved waste repository issue. No ration economic actor will engage in construction of such plants.
This attributes the lack on interest in nuclear power investment entirely to regulatory and legal issues rather than any intrinsic problem with competing with other power investments in the marketplace.
I would direct interested readers to a very good recent study on the issue of nuclear power:
"The Future of Nuclear Power" at http://web.mit.edu/nuclearpower.
Referring to pg. 41 of the study: "under what we consider to be optimistic, but plausible assumptions, nuclear is never less costly than coal."
The fundamental problem is that nuclear power has an intrinsic high capital cost that makes it hard put to compete with other forms of energy that have lower capital costs. This is *not* a function of regulatory delay.
The MIT analysis excludes a couple of factors that makes the barrier to investment even higher. The estimated cost of nuclear power is valid (given that all the optimistic assumptions prove out) over the expected (40 year) life of the plant. But investors want a faster pay-out, the faster the better. Given equal cost power, they will prefer plants that achieve this cost over a shorter time period - i.e. ones that are less capital intensive. So even if nuclear power matches coal in cost or is marginally superior, over the planned plant life, it will still be discriminated against by investors. (Another disincentive that Decker-Mage mentions above is potential legal liability.)
Unless there is some penalty applied to coal generation that limits capacity added, or drives up the cost, nuclear power is not going to complete in a market-driven power business. (This capital cost problem afflicts solar power also.)
Regulatory intervention in the power production industry is going to be required to restrain the growth of CO2-releasing coal power. Carbon taxes are one possibility, requiring carbon capture and sequestration is another.
Without a doubt any statement that "they" said this or that is vague to the point of meaninglessness, BUT - who was this "one moronic U.S. bureaucrat"?
The aforesaid "American bureaucrat, Lewis Strauss," was in 1954 none other than the Chairman of the U.S. Atomic Energy Commission, the Czar of all things atomic in the U.S. at the time.
Certainly it was a foolish and ignorant thing to say (he was responsible for other notable travesties) but he was also the top government official in charge of nuclear energy.
It is a bit like referring to the remarks of Condoleeza Rice on matters of national security today as being simply those of "one moronic U.S. bureaucrat".
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Do you think Hollywood is going to turn over the rights to let you copy whatever you want of their stuff for a few paltry million $ that this would bring in?!?! Even if every single internet user in the United States paid $5 (much less the pathetic $1 you're suggesting), that would only be about $775 million.
Paltry? Umm... in December 2006 there were 82.5 million active broadband lines in the U.S. (see: Networked Nation: Broadband In America 2007). The proposal is $5 per month per broadband customer. This is $5 billion a year, even at December 2006 adoption rates. It will climb higher in years to come as broadband penetration increases.
For comparison this is almost half of the recording industry's revenues from 2006. And this would be essentially all profit. For this kind of gift (if they could get it) the public should demand the sky in freedom to do whatever it likes with the recording industry's products. Even a $1 fee would likely more than double its annual profits.
This proposal should be no surprise to anyone. The recording industry has become accustomed to having the government impose special taxes to provide it with revenue under the theory that these taxes compensate it for (unproved) lost sales through piracy.
See: USC Title 17, 1008 "Royalty Payments". This is a tax imposed on music CD-Rs, digital audio tapes, stand-alone CD recorders, and digital audio recorders. In 1998 the RIAA tried, but failed, to get special taxes imposed on MP3 players.
Notice that these are taxes on *digital* devices. Analog technology (blank vinyl disks and vinyl recording devices, analog tape and recorders) never had these levies, and yet the industry survived just fine.
At the same time the industry has been obtaining access to tax revenues (originally under the theory that this was a trade-off for more liberal copyright restrictions) it has also been seeking, and getting, increasingly draconian revisions of copyright law.
In all, the recording industry has had some success in using computer technology as a scare tactic to stampede congress into granting it immense new assets at the public's expense. Despite its great success in this copyright land rush, it is still crying poverty, hoping for even greater gains. Its lots easier than running a successful, adaptable business. The MP3 episode shows though, that these attempts can be resisted.
Everything you say is true, but is not relevant to his definition of fairness... Not to say you aren't right, but he's a mathematician and not a politician...
Quite so, and to get a publication out of the issue he has to offer a new and more complicated method than any of the historical ones. An excellent study of this issue was prepared by the Congression Research Service six years ago.
The upshot of this report is that the current method (the Hill method) is one of the best ones ever implemented or seriously proposed. But the triviality of this issue can be judged from the fact that this report shows that if the Hill method were replaced by the simplest and earliest proposed method (the Hamilton-Vinton ranked fractions method) only one single seat in the 2001 House would have changed hands.
Given the extreme favoritism to tiny states that the current Senate and Presidential representation schemes provide (the latter through the Electoral College), it is not at all evident that there is a problem here in need of fixing.
Wonderful deal, isn't it? Iran only has to build expensive reactors, and buy the fuel from the US (or whoever provides it) which will of course be sold at a profit (so it's not exactly a huge concession on the provider's part) That'd work right until the provider decides it doesn't like something going on and says "No more fuel for you!".
Um. Do you realize that enriched reactor fuel is a competitive market, with at least three suppliers competing for business: the USEC (in the United States), URENCO (a western European consortium), and Russia. SWUs (separative work units), the standard measurement of enrichment, are an industrial commodity which can be purchased (you supply the uranium) for a small fraction of what Iran's domestic enrichment would cost. Iran is not saving itself from extortion by greedy capitalists. It is incurring huge financial, and potentially huge political costs, to make something that it can buy cheaply and easily from numerous sources (for legitimate commercial use, that is). The market for enriched uranium is much more competitive that is the market for, say, oil.
China is entering this business and Australia is currently hot to get into it also. Iran has no shortage of eager potential suppliers, and in fact has one right now: Russia! In case you missed it, Russia shipped Iran its first fuel loading this week. As an active geopolitical rival to the U.S., and ever eager to build its power and influence on its southern border, Russia is certain to continue to ignore any U.S. effort to deny Iran uranium fuel for its domestic power plants.
Whatever the reason Iran has for pursuing domestic enrichment, it is not to save money or to safeguard access to low enriched uranium for commercial use.
Compelling evidence? Lets see...
1. That there have been far more events in recorded history similar to Tunguska which have been volcanic or geologic in nature... Mt. Saint Helens ... Krakatoa ... Lake Nyos... And which of these are examples of the supposed megaton range methane gas explosions? Why... none of them. Sorry, unrelated geophysical events don't provide any precedent for the proposed mechanism. The notion seems a bit difficult to buy into - the explosive limits for methane in air is usually quoted at 5-15% by volume, to make a mammoth blast you would need to establish this specific concentration range with millions of tons of methane, and have it ignited at the proper time. How does this happen geophysically? Any actual examples?
2. That there was swamp land in the center of the Tunguska caldera. This is a typical place for methane to build up. But... millions of tons? Capable of sudden release? People should be finding commercial exploitable methane gas deposits in the surface strata of swamps I should think.
3. The directions in which the trees had been knocked down indicated two discrete blast points some distance from one another. If this was observed, a twin asteroid would be a reasonable explanation (recent probe and radar evidence shows asteroids to frequently consist of loosely bound multiple bodies).
4. There were odd glowing clouds seen over the area in the nights leading up to the explosion which could be explained by methane collecting in the sky. Reports on the Tunguska event I have seen report glowing clouds in the sky afterward, not before.
5. No impact crater was found. Only the very rare iron asteroids are strong enough to make ground impact in this size range. The far more common stony bodies will fragment and explode in the air. This is a complete red herring.
6. No meteorite was found. This is a red herring like 5. It exploded high in the air. The extraterrestrial particles found are the meteorite.
The whole notion that this is an unprecedented event that requires alternate explanation is utterly wrong. Atmospheric explosions of extraterrestial bodies are regularly documented events. The Defense Support Program (DSP) has monitored atmospheric explosions since the 1960s and has found Hiroshima-sized (16 kt) events occurring about once a year. A simple statistical distribution permits calculating the frequency of larger events, a 10 Mt event is expected once very 120 years. See: an item about this in the Acoustical Society of America's newsletter. This being the case, there is really no anomaly here to be "explained away". Bolide explosions are a regular occurrence and we should see some in the megaton range in the historical record - most of course occur over open oceans and have had few witnesses and left no evidence.
Living things are, in general, very competitive, and very effective competitors. Otherwise, they wouldn't still be here. So the odds that a new abiogenesis event, if one occurred, would produce a lifeform that would actually be viable in the face of a billion years of evolution by the competition are, I think, remote.
...
Finally, while it is true that many lab techniques are specific to detecting conventional terrestrial life, others are not. So, unless this non-conventional life is *restricted* to some remote environment - which conventional life certainly is not, so this again seems unlikely - we would be expected to have seen it.
There are some exotic coincidences which might allow for this to be true - maybe this exotic life looks just like a bacterium under the microscope, but for whatever reason cannot be cultured at all. Maybe it can't live on sugar - maybe it requires some other exotic organic nutrient which is found out in the wild but no-one has thought to add to culture medium. All possible, but also all unlikely.
The undercurrent of thinking in the above (which is the historically dominant one addressed in the opening paragraphs of the article) could be summarized as: "If a fundamentally distinct form of life existed, we should of seen it by now, since science has by now pretty thoroughly explored all of the Earth's environments, and its organisms. So our current status of non-observation is very strong evidence of non-existence."
If this premise of thorough characterization of the biosphere is correct, then we shouldn't have had any radical new discoveries about the diversity of conventional life in, say, the last 30 years either.
In fact there have been quite a number of truly astonishing discoveries of this nature. Most prominent was the discovery of the third kingdom of life on Earth, the Archaea, in 1977 by Carl Woese. The Archaea is a branch of life as different from the other two branches (Bacteria and Eukarya) as they are from each other. Yet science, well advanced by any standard at that point, had failed to notice it. See, for example Virginia Morell's write-up on the Woeseian revolution in Science, 2 May 1997, Vol. 276. no. 5313, pp. 699 - 702, or Carl Woese.
Another example concerns the very extensively studied kingdom of Bacteria. It stands to reason that by the later 1990s the bacteria in any common soil sample must have been pretty well characterized, right? After all, these are ideal subjects of study, readily available, conveniently small but not too small for study. Microbiologists had been culturing and classifying them for a few centuries by then. Except that when examinations of how many bacteria could be visually counted in a typical sample was compared to the number that could be cultured, it turned out that less than 1% of the bacteria could be grown for study. And when it became possible to do mass screening of DNA fragments in the environment it turned that less than 1% of the fragments from a common soil belonged to organisms known to science. So it transpired that biology was familiar only with the bacteria that could be easily grown in the lab, which turns out to be hardly any of them. See for example: A Molecular View of Microbial Diversity and the Biosphere by Norman R. Pace in the same issue of Science above (pp. 734 - 740).
Other examples. It was discovered in 1977 that pelagic bacteria, previously unnoticed, accounted for most of the biosphere mass in the oceans, and most of its biolgical activity. Here we had the largest component of the entire biosphere of Earth escaping notice! Similarly, the most prevalent organisms in the oceans turns out to be viruses (but are lower in mass since they are much smaller), yet these escaped notice until 1989. See: "Microbes, Molecules, and Marine Ecosystems" by Farooq Azam and Alexandra Z. Worden in Science 12 March 2004: Vol. 303. no. 5664, pp. 1622 - 1624.
A
This is true, but it's only because it's a binary solution set. Until or unless SETI finds a transmission, it will have made no progress in finding one, only in not finding one.
Progress in not finding one is very important progress in itself. SETI in the only means we have of gaining understanding of the Fermi Paradox: the fact we know intelligent life is possible, and that there are no identifiable physical limits that prevent intelligent life from making its presence not only detectable but ubiquitous. The absence of detectable signatures of intelligent (and technological, an important qualification) life tells us something fundamental about the Universe, the nature of intelligence, and ourselves. What exactly it tells us remains for us to figure out.
It is a foolish and unscientific tendency to view negative evidence as being worthless. If we have a reason to believe that something should or could exist, we should definitely devote effort to looking for it - be it magnetic monopoles, nanobacteria, cosmic strings, deviations from special or general relativity, etc. We can only establish rarity, or absence, by actually looking for the evidence. An extensive and systematic SETI program, spanning centuries, that never turns up anything would provide us with powerful constraints on the limits of intelligent life in the Universe.
This whole post is fictional history. Some statements in it are factual but the story, as presented, is false.
Japan was actually getting serious about the possibility of a fission bomb, Germany wasn't. Some historians think it was because Germany's racial doctrine was so aggressively disparaging of 'Jewish' physics, and so their research and funding ended up being steered in other directions. Japan had physicists who weren't afraid to use Einstein's or other Jewish physicists work in their own papers.
This a confused mishmash of half-facts and outright falsehoods. Nazi purges of academia had lost them a good portion of their best physicists who were either Jewish, or communists, or were non-Germans who simply had had enough of the regime. But Germany was the world center of physics at the time and they still had many, many highly competent physicists. Nazi doctrines had no influence at all in the practice of science by scientists. See Alan Beyerchen's excellent "Scientists Under Hitler".
In September 1940, the Japanese Army controlled Institute of Physical and Chemical Research, or Rikken, was assigned a preliminary project. In 1942, the Japanese Navy began also (somewhat independently of the Army) working on a Uranium based fission device. The project was called F-Go {or sometimes just No. F, for fission].
This much about Japan's effort at least is more or less correct, although the Japanese Army did not control the Riken (correct spelling, Rikken is a Dutch card game). The two research programs, NI-Go and F-Go, together constituted a tiny effort by a nation short on scientists and advanced industry. The total peak employment of both programs combined, including assigned military officers was 55 people, and the total amount of money appropriated to the effort was $350,000. The U.S. effort employed 2000 times as many people, and spent 5000 times as much money. In all of Japan there were only 30 active physicists, far too few to staff a serious fission effort. See Walter E. Grunden, "Secret Weapons and World War II: Japan in the Shadow of Big Science", University Press of Kansas, 2005.
This was located at Kyoto, and was actually the chief reason why Kyoto was added to the list of potential military targets for the U.S. bombs,...
This is simple fantasy. No such consideration ever came up in the work of the Target Committee.
True, though a vast understatement. The Japanese project had only prepared a few grams of ordinary uranium metal, had only a few hundred kilograms of crude uranium compounds on hand, and had not enriched even a microgram of uranium above natural levels. Really, the program had no results at all, and thus could hardly be said to have even truly begun.
A Japanese plant, concealed in Hungnam, now part of North Korea, may have been the source of heavy water subsequently used by the USSR for its own bomb research. There are reports the Soviet Union continued to run that plant and collected the output every other month by submarine, and it alone may have shaved a year or more off the USSR's development time.
All of the above is fantasy.
In May 1945, a German submarine which surrendered to US forces , was found to be carrying over 500 kg. of Uranium oxide destined for Japan. The oxide contained about 3.5 kilograms of isotope U-235. While not enough to make a bomb, that was a sizable fraction of one.
A bit like evaluating a pile of iron ore in terms of the number of jet engines you could potentially make out of it. That such a small quantity of uranium compound was considered significant by Japan indicates how short of resources they were.
After the Japanese surrender, the occupying US Army found five cyclotrons which were capable of separating fissionable material from ordinary uranium.
The U.S. Army didn't "find" them. They weren't secret
The basic idea is to create a small fission (not fusion) explosion using magnetic compression. Nuclear weapons use chemical explosives to create an implosion, and during the implosion the fissionable material is compressed hard enough to get a 1.5x to (maybe) 2x density increase. With magnetic compression, a small pellet can be compressed hard enough to get a 10x density increase. This allows smaller explosions, around 50 gigajoules instead of the 20 terajoules of a fission bomb. They want to use curium or californium as the fuel, rather than plutonium.
The experimental work (they compressed an aluminum cylinder with a big magnet at Sandia) was done back in 2002. This isn't really under active development... It's not a totally unreasonable idea, but it would be a huge job to make it work.
Good post.
To expand upon it a bit, I will observe that actual pressures and compressions demonstrated so far are maybe a couple of orders of magnitude below what is needed to achieve 10-fold compression of fissile material. They demonstrated pressures of 2.4 megabars (atmospheres) and roughly two-fold compression in aluminum, performance generally similar to what high explosive implosion systems have produced for over 50 years. Despite decades of work, HE implosion has never been scaled to the pressures or compressions postulated for this. See: APS and AIP pages on this.
Now, their ace-on-the-hole is that they can achieve isentropic compression (i.e. optimal compression, without heating) explosive systems cannot, but even so they aren't in the ball-park with this, only looking at it with binoculars. And the Z-machine is a huge immobile installation. How to convert a grossly souped up version of it to practical flight-ready hardware would be a staggering task.
So this is in the same league as commercial fusion power. A concept that has some grounding in reality, but possibly one forever beyond practicality, and certainly beyond the working career of any living engineer.
Hey, it could happen. It's just hard to remember, as for the last 16 years we've had no one but Clinton and Bush. I remember the first time I really paid attention to Bush on TV, after he won his first nomination. I remember thinking, "holy cow, the lefties are going to hate this guy every bit as much as we righties hate Clinton." And I was right. But it doesn't have to be that way.
So far, so good.
Of course it would be with Hillary. With Obama, I think it would just be a general disgust at his incompetence, like with Carter. The key is whether the person will polarize or unite the center. Someone like Fred Thompson, I think would likely win them over, the way Reagan did. If Newt runs, it's hard to say. He eventually lost the center to Clinton as house speaker, but first he masterminded the Contract with America and won Congress for the Republicans by winning them over. But if he had the machinery of a presidential campaign with which to respond and react to the MSM, who knows?
And now we get content-less denigration of four Democrats, and praise for three Republicans (plus a quick dig at the "main stream media").
This type of party-line thinking is just exactly why it currently happens to to "be that way".
A couple of billion years ago, you'd be right, but the heat inside the earth today is sustained by radioactive decay. There's also some heating due to tidal effects as the planet gets tugged on by the sun and moon as it rotates. Heat from solar radiation doesn't really penetrate, but the warmer the ocean and the atmosphere are, the less heat escapes from the interior.
A neat paper on the Earth's heat budget is located at http://www.geo.arizona.edu/geo5xx/geo519.071/lectu res/Heat_Budget_Earth.pdf.
The capsule summary:
* A variety of sources heated the Earth immediately during formation: gravitational collapse, adiabatic compression, and short lived radioactivities that quickly disappeared. Gravitational collapse may not have contributed much heat to the inner Earth because it could have been mostly dissipated during accretion, but this is uncertain.
* Today decay of U, Th and K produce something like 40-75% of the observed total heat flux from the Earth. Solidification of the core (heat of fusion) produces about 10%. Cooling of the ancient heat deposited in Earth's formation is 15-50% of the flux.
* So - there is a lot of uncertainty here. It is most likely that radioactive decay dominates over simple cooling of ancient heat today, but this is uncertain. If one includes core solidification as a form of ancient heat (it is latent heat of formation) then the likelihood of radioactive decay dominance diminishes and it becomes possible that ancient heat still dominates today.
If there's one thing that Slashdot has taught me: never underestimate the power of a mob of self-righteous "environmentalists" with entirely too much money and free time on their hands.
Ah yes, those ultra-rich, super-powerful environmentalists that have those impoverished multi-national corporations everywhere on the ropes! As you say, it must just be that they have tremendous amounts of free time to waste. It is not as if environmental degradation has ever been a problem anywhere.
Still - it might be nice to thoroughly explore Mars first and determine conclusively whether it has a native biosphere or not, before utterly destroying its natural climate. We might learn something, and some of that knowledge could even turn a buck! Making money is, after all, what is really important here (just keep it out of the hands of those environmentalist plutocrats!).
Just a reality check on this particular complaint:
Most commercial farmers (at least in the industrialized world) plant hybrid seeds (technically F1 hybrids), and have for the better part of a century. F1 hybrids aren't sterile, but they also can't be replanted because the desirable hybrid traits are lost in the F2 generation. Not being able (in a practical sense) to save seed and replant is nothing new, its classical plant breeding. A large majority of commercial farmers don't save seed, or want to, they repurchase each season as just one of many expenses involved in the business of farming.
anything to stop the people from acting responsibly?
Unfortunately the global warming problem is so severe that even a magic wand that shuts off all carbon dioxide production worldwide today, and stripped away all CO2 released over the last 7 years, wouldn't stop continued warming for most of the next century (though it would markedly reduce it). See page 13 of: the IPCC Working Group I Fourth Assessment Report Summary for Policymakers. Even extremely optimistic scenarios for reducing CO2 release lead to warming over the next century three of more times greater than the "magic wand" solution.
Although acting responsibly is certainly necessary, the situation has reached the point where even immediate dramatic responsible action (not yet in evidence, sadly) will not avoid severe climate change in coming decades and centuries. To reduce the scale of the developing disaster additional measures may be necessary.
Crutzen's stratospheric sulfur injection proposal has the advantage that natural experiments have already proven that it works. The eruption of Mt. Pinatubo in 1991 was a recent example.
A recent report on this in Science was: Science 20 October 2006:
Vol. 314. no. 5798, pp. 452 - 454,
"A Combined Mitigation/Geoengineering Approach to Climate Stabilization"
T. M. L. Wigley
Summarizing Wigley's findings, Richard A. Kerr in the same issue stated:
Not really. Decay time due to drag for LEO is fairly short. Debris in orbits below 300 km (where ISS lives) falls in less than 30 days. Debris up by the Hubble can stay up for years, but will fall eventually. Here is a chart of orbital decay vs. altitude.
This is correct. At low enough altitudes space debris does not cause a run-away debris scenario. This point was made in the New York Times article - if the Chinese had conducted their test at the ISS orbital altitude there would be no long term problem (just a medium term one for the ISS).
In fact drag automatically clears debris below about 700 km, eventually, but not above that altitude. There was a good article on this a year ago in Science: "Risks in Space from Orbiting Debris" by Liou and Johnson (20 January 2006: Vol. 311. no. 5759, pp. 340 - 341). They published a debris vs altitude chart for 2004, 2104, and 2204 showing that (assuming nothing else is launched into space), the existing debris cloud would be entirely cleared below 400 km in 100 years, and at least reduced below today's density between 400 and 700 km. Above that altitude the density keeps climbing century after century. By far the worst hazard is between 800 km and 1050 km.
This limits the hazard to a certain band of orbital altitudes, a fact not brought out in the news article. It isn't a denial of space by any means, but it is a significant restriction on usable orbits.
Ok, this is odd. Your criticism is spot-on about Fermi, but also shows you didn't read the paper, where he does indeed address (badly) the concepts of self-replicating probes and the like. He just thinks they are a bad idea. Not infeasable, mind you, just a bad idea so nobody would build them. So yes, it's a very naive study, but you do have to do even such papers the credit of reading before saying they don't consider geometric growth.
It's true I hadn't read it, I was having trouble downloading the PDF and went by the Guardian article and the Arxiv abstract. But after having read it, my point is the same - considering a special case (a small fixed number non-replicating of probes launched by just one civilization) fails to address the Fermi Paradox at all.
His major finding is that with a fixed number of probes, n, the time to explore the galaxy is linear in the number of probes (not too surprising, that). So if n is sufficiently small then there won't have been enough time. He prefers a number of about 20 probes/subprobes, but was willing to consider as many as 1800 (which would actually cover the entire galaxy in about its actual age, according to his model). Why these small numbers? Well, you see, these probes are expensive so he assumes that not many would ever be launched. If he had instead assumed a low continuous launch rate of, say, one per thousand years then the entire galaxy would have been explored in 200 million years. So his claim to address the paradox fails even within the limitation of one civilization and non-replicating probes.
He does mention replication but utterly fails to clear the high hurdle I described required to dismiss it. He simply argues it seems like it might be a bad idea to let self-replicating probes loose. Maybe. But then you just keep them at home, and sterilize them (so that they cannot replicate) before letting them go. Then you have a geometrically increasing launch rate of non-replicating probes that would explore the galaxy in about the time it takes to traverse it: one million years at the assumed 0.1 c.
The reasoning above is why I believe the Prime-Directive/Zoo thesis is the most likely Fermi answer. That only requires that one intelligent race, the one that controls our neighbourhood, wishes to hide from us the evidence of ETs. The "we've in a virtual universe" answer also meets that requirement.
This solution does actually address the problem, but it is analogous to the creationist Omphalos argument that God created the world (and universe) 10,000 years ago and fabricated all the evidence to give it an apparent age that was much older. Seems unsatisfying. (Especially since if you accept it then the moment of creation could have been 10 minutes or 10 seconds ago).
Can anyone propose a test to prove that we aren't living in the Matrix?
The study in question does not even address the Fermi Paradox in any meaningful sense, much less "resolve" it. In fact, if this study is being offered as a resolution of the Fermi Paradox then it suggests the researcher does not understand why the Fermi Paradox is a paradox at all.
The fundamental difficulty with any explanation offered for the complete absence (so far) of any sign of other intelligent life in the universe is that the proposed explanation has to be universally valid.
The span of time for colonization, or dispersal of replicating probes, or of building vast telescopically detectable artifacts is so great that even one single exception from any proposed explanation would be capable of generating ubiquitous evidence in a tiny fraction of the life of the Universe.
Simply describing some model for exploration, and then arguing that this model won't do the job says nothing about other models. This study apparently does not consider the geometric growth that occurs with any exploration program that uses some form of replication of explorers, for example. If replication is thought to be impossible then the study would have the high hurdle of convincingly demonstrating this. (The material evidence of life on Earth seems to argue persuasively against it though.)
Arguments that "interstellar travel is impossible" would qualify for explaining why alien artifacts aren't being found locally (but do not address communication signals or telescopically detectable artifacts), but require convincing arguments that this is indeed true. On the contrary, physics does not seem to make this impossible at all, just very costly and slow. Too costly and slow for anyone to bother? Not even one single civilization?
The Fermi Paradox seems to be telling something important about the Universe. If only we knew what it is...
From a quick scan - "Even with aggressive assumptions about biological productivity, we project costs for biodiesel which are two times higher than current petroleum diesel fuel costs".
If that was in 1998, then at should be very feasible with current petrol costs, especially taking into account the added value of removing CO2 from the atmosphere.
Indeed so! The 2006 inflation adjusted price in 1998 was $18 a barrel, last I checked it was three and half times this right now. In fact the average inflation adjusted price over the last 33 years is about double the 1998 price.
If the DOE algae biodiesel cost estimate is correct then it has already been on average a break-even technology for a third of a century.
Both the total world production of oil and the production of oil available for export are peaking about right now. This has been predicted for years: http://www.energybulletin.net/147.html and current studies verify this.
Thus the cost of oil is not likely to experience any significant downward trend from now on, ever.
The original article's production estimates are a bit suspect though. The 20,000 gallons of biodiesel per acre they give as the upper range of production is 47 g/square meter a day. The DOE gives a maximum annual production of 50 g/square meter of algae (not biodiesel) a day.
Still, the technology looks really good.
A lethal dose of polonium-210 is an absorbed dose that will deposit about 600 rads (or 600 centigrays, cGy) of internal radiation exposure before it is eliminated from the body. Given its biological half-life of 30 days, this quantity can be calculated at 4 millicuries (4 mCi, 1.5x10^8 Bq) for an 80 kg man. This is only 0.9 micrograms. Not all of an orally administered dose will be absorbed, so the actual amount that would result in lethal poisoning is more than this.
l
The largest amount of Po-210 that can be purchased in the U.S. without a special license is 500 microcuries. The most abundant readily available commercial source for this is in Staticmaster® Brushes:
http://www.2spi.com/catalog/photo/statmaster.shtm
which contain 250 microcuries absorbed on a plastic resin. This is 2,500 times the amount in the source from United Nuclear. The Staticmaster replacement element (without the brush) can be bought for $20.
Extracting the polonium from, say, 30 Staticmaster elements would take a bit of skilled chemistry. The elements would need to be dissolved and the polonium freed, and it would then need to be concentrated into a modest amount of palatable material. Handling polonium is tricky, it is volatile and is notorious for its ability to "migrate" around the lab (which may account for the contamination found at various sites which Litvinenko visited).
It should be noted that Aleksandr Litvinenko was poisoned with far more than 4 millicuries. A minimal lethal dose would take more than a week to accumulate enough exposure to cause apparent illness, and lethal levels would take a month or more to accumulate with death following weeks later. Litvinenko became ill within one day (it appears), and was dead just over three weeks later. Given the latency of death from Acute Radiation Syndrome (ARS), he must have accumulated a lethal dose within a day or so. The amount administered was likely dozens of times the lethal level.
One possible explanation for the rapid onset of illness and (for radiation poisoning) quick death is that the radiation-sensitive lining of his gastrointestinal system was destroyed before and during the absorption of the polonium. The gastrointestinal subsyndrome form of ARS is very lethal and kills in about three weeks. The transient concentration of polonium in the GI tissue would have been very high, and even polonium that was not absorbed would irradiate the lining.
The economics of fusion power are, unfortunately, quite depressing. There was a short article on this in Science, 10 March 2006 (p. 1380). It estimated that the the capital cost for the blanket-shield alone in a 1 GWe powerplant "amounts to $1800/kWe of rated capacity--more than nuclear fission reactor plants cost today". All the other extravagantly high tech equipment and construction costs are in addition to this. It posits a total capital cost of $15,000/kWe of plant rating.
Is there any other alternative energy scheme that is seriously proposed that is *more* expensive than this?
This attributes the lack on interest in nuclear power investment entirely to regulatory and legal issues rather than any intrinsic problem with competing with other power investments in the marketplace.
I would direct interested readers to a very good recent study on the issue of nuclear power: "The Future of Nuclear Power" at http://web.mit.edu/nuclearpower.
Referring to pg. 41 of the study: "under what we consider to be optimistic, but plausible assumptions, nuclear is never less costly than coal."
The fundamental problem is that nuclear power has an intrinsic high capital cost that makes it hard put to compete with other forms of energy that have lower capital costs. This is *not* a function of regulatory delay.
The MIT analysis excludes a couple of factors that makes the barrier to investment even higher. The estimated cost of nuclear power is valid (given that all the optimistic assumptions prove out) over the expected (40 year) life of the plant. But investors want a faster pay-out, the faster the better. Given equal cost power, they will prefer plants that achieve this cost over a shorter time period - i.e. ones that are less capital intensive. So even if nuclear power matches coal in cost or is marginally superior, over the planned plant life, it will still be discriminated against by investors. (Another disincentive that Decker-Mage mentions above is potential legal liability.)
Unless there is some penalty applied to coal generation that limits capacity added, or drives up the cost, nuclear power is not going to complete in a market-driven power business. (This capital cost problem afflicts solar power also.)
Regulatory intervention in the power production industry is going to be required to restrain the growth of CO2-releasing coal power. Carbon taxes are one possibility, requiring carbon capture and sequestration is another.
Without a doubt any statement that "they" said this or that is vague to the point of meaninglessness, BUT - who was this "one moronic U.S. bureaucrat"?
The aforesaid "American bureaucrat, Lewis Strauss," was in 1954 none other than the Chairman of the U.S. Atomic Energy Commission, the Czar of all things atomic in the U.S. at the time.
Certainly it was a foolish and ignorant thing to say (he was responsible for other notable travesties) but he was also the top government official in charge of nuclear energy.
It is a bit like referring to the remarks of Condoleeza Rice on matters of national security today as being simply those of "one moronic U.S. bureaucrat".