You know something is complicated and "out there" when someone who posts at Cosmic Variance finds it new and hard to fathom. Have a look at this post about "Boltzmann brains" and the decay of the universe. More detail about Boltzmann and entropy is at an earlier CV post here. It is not easy going.
I will soon be doing a post about cosmologist Frank Tipler too, and his upcoming book claiming to show the physics behind various miracles in the Bible (or the New Testament, at least.) His previous book "The Physics of Immortality" got rubbished by most of his scientist colleagues, but I expect that will be nothing compared to the shellacking the new book is likely to take.
Thursday, February 22, 2007
Targetting for beginners
Former Spook, who has some experience in these matters, has a good post explaining why people should not think there is anything unusual going on when the media runs a "targets have been selected already" story.
Wednesday, February 21, 2007
Debating the multiverse
Here's an interesting account of the recent debate at a conference between top cosmologists who take opposing sides on the issue of the anthropic principle and whether a "multiverse" exists. (String theory gets a mention too.) It explains the issues in pretty straightforward fashion, and is well worth a read.
Tuesday, February 20, 2007
Good surgeons play with monkey
OK, something surprising to post about.
The LA Times notes:
New research today found that surgeons with the highest scores on "Super Monkey Ball 2," "Stars Wars Racer Revenge" and "Silent Scope" performed best on tests of suturing and laparoscopic surgery.....
"For as little as three hours a week, you could help your children become the cyber-surgeons of the 21st century," said Dr. James C. Rosser Jr. of Beth Israel Medical Center in New York and lead author of the study in the Archives of Surgery.
The research looked at 33 surgeons attending a course on laparoscopic surgery and found that their game-playing skill was a better predictor of success on the surgical tests than years of medical practice or number of surgeries performed.
Expertise with "Super Monkey Ball 2," which involves steering a ball containing a monkey down a serpentine track while simultaneously targeting bananas, was most closely linked with high test scores.
The LA Times notes:
New research today found that surgeons with the highest scores on "Super Monkey Ball 2," "Stars Wars Racer Revenge" and "Silent Scope" performed best on tests of suturing and laparoscopic surgery.....
"For as little as three hours a week, you could help your children become the cyber-surgeons of the 21st century," said Dr. James C. Rosser Jr. of Beth Israel Medical Center in New York and lead author of the study in the Archives of Surgery.
The research looked at 33 surgeons attending a course on laparoscopic surgery and found that their game-playing skill was a better predictor of success on the surgical tests than years of medical practice or number of surgeries performed.
Expertise with "Super Monkey Ball 2," which involves steering a ball containing a monkey down a serpentine track while simultaneously targeting bananas, was most closely linked with high test scores.
No news today
My morning survey of the news is showing nothing I particularly care to post about. Instead, for diversion, have a look at this website for "weird and funny" photos. (Originally I found it via Red Ferret Journal, which linked to the post about cool aircraft-in-flight cockpit photos. However, the rest of the Static website is worth looking at too.)
Monday, February 19, 2007
The cause of ice ages
It would give everyone a greater degree of confidence in climate predictions if scientists had cracked once and for all the issue of what triggers ice ages. As this post at Real Climate makes clear, they are still several theories around, and no doubt more to come. (Cyclic orbit changes are a significant part of it, but the exact mechanism seems still very much up for grabs.)
The comments to the post include these one, which I add here just to give some background on the whole history of ice ages:
...the question "What triggers ice ages?" only applies to the late Pleistocene (since about 800,000 years ago). From the onset of northern-hemisphere glaciation (about 3 million years ago) to the "mid-Pleistocene transition" (about 800,000 years ago), glacial advance and retreat follows a strong 41,000-year cycle, which has led to its being called "the 41 ky world" (Raymo & Nisancioglu 2003, Paleoceanography, 18, 1011). This is surely due to the changes of earth's obliquity, since changes in the amplitude of the climate signal correspond to changes in the amplitude of the obliquity cycle (Lisiecki & Raymo 2007, Quaternary Science Reviews, 26, 56).
But since the mid-Pleistocene transition (not precisely since, this happens intermittently before that time) glacial changes are dominated by a 100,000-year cycle. The behavior during the "late Pleistocene" was originally attributed to changes in earth's eccentricity, but that idea has now fallen out of favor. Huybers & Wunsch (2005, Nature, 434, 491) and Huybers (Quaternary Science Reviews, 26, 37) have convincingly shown that even during the late Pleistocene, the timing of deglaciations is strongly correlated to the obliquity cycle. They find no such relationship for the precession cycle or the eccentricity cycle.
(This comment seems to be by someone the scientists who run Real Climate trust.)
And this comment is make by one of the Real Climate authors, in response to the question of when would we be next due for an ice age were it not for global warming:
We've just come out of one of the big every-100KYr glaciations, and the normal course of events is to build up to another biggy through a series of small, short glaciations over the next 100KYr. In the normal course of events, the first try at an ice age would be due sometime in the next 20,000 years but I myself wouldn't try to pin it down more than that. One of the most interesting attempts so far to say what global warming might do to the glacial cycle is in the paper (pdf) by Archer and Ganopolski that appeared in the AGU journal GGG. I'll leave it to David to say whether that has been followed up by more detailed GCM work.
By the way, I don't post this to express scepticism about legitimate concern over CO2 levels, but it is interesting that something as significant as ice ages are not properly understood yet.
The comments to the post include these one, which I add here just to give some background on the whole history of ice ages:
...the question "What triggers ice ages?" only applies to the late Pleistocene (since about 800,000 years ago). From the onset of northern-hemisphere glaciation (about 3 million years ago) to the "mid-Pleistocene transition" (about 800,000 years ago), glacial advance and retreat follows a strong 41,000-year cycle, which has led to its being called "the 41 ky world" (Raymo & Nisancioglu 2003, Paleoceanography, 18, 1011). This is surely due to the changes of earth's obliquity, since changes in the amplitude of the climate signal correspond to changes in the amplitude of the obliquity cycle (Lisiecki & Raymo 2007, Quaternary Science Reviews, 26, 56).
But since the mid-Pleistocene transition (not precisely since, this happens intermittently before that time) glacial changes are dominated by a 100,000-year cycle. The behavior during the "late Pleistocene" was originally attributed to changes in earth's eccentricity, but that idea has now fallen out of favor. Huybers & Wunsch (2005, Nature, 434, 491) and Huybers (Quaternary Science Reviews, 26, 37) have convincingly shown that even during the late Pleistocene, the timing of deglaciations is strongly correlated to the obliquity cycle. They find no such relationship for the precession cycle or the eccentricity cycle.
(This comment seems to be by someone the scientists who run Real Climate trust.)
And this comment is make by one of the Real Climate authors, in response to the question of when would we be next due for an ice age were it not for global warming:
We've just come out of one of the big every-100KYr glaciations, and the normal course of events is to build up to another biggy through a series of small, short glaciations over the next 100KYr. In the normal course of events, the first try at an ice age would be due sometime in the next 20,000 years but I myself wouldn't try to pin it down more than that. One of the most interesting attempts so far to say what global warming might do to the glacial cycle is in the paper (pdf) by Archer and Ganopolski that appeared in the AGU journal GGG. I'll leave it to David to say whether that has been followed up by more detailed GCM work.
By the way, I don't post this to express scepticism about legitimate concern over CO2 levels, but it is interesting that something as significant as ice ages are not properly understood yet.
Japanese culture corner
The Japan Times has an article about the declining popularity of period drama in Japan. You know: samurai, ninja, some very strange haircuts and all. The casual visitor to Japan will still find quite a bit of it on TV, but apparently not as much as before.
I guess it's a similar phenomena to the decline of the Western as a genre. Anyone who was a child in the '60's can remember just how many cowboy and wild west shows were made in those days. I suspect the 1950's was probably the height of its popularity in the cinema, but I could be wrong. TV now is dominated by gritty crime shows, I suppose, and plain crap of all varieties. (Someday, a good sitcom about adults that doesn't always deal with sex will emerge again.)
Anyway, this got me thinking about the one childhood Japanese show that I can recall - The Samurai. The Wikipedia entry is relatively short, but points out that the show was very popular in Japan, Australia and the Phillipines, but was hardly shown anywhere else. How odd.
For those who can vaguely recall what the lead character Shintaro looked like, here he is:
(The picture is from a small fansite here.) Not exactly rugged good looks, but a sister-in-law of mine used to swoon over him, so she tells me.
I think most kids were most impressed by the evil ninja who jumped up backwards into trees, snuck around the houses with paper walls, and had an endless supply of throwing stars.
It would probably be seen as hopelessly violent for children today.
I guess it's a similar phenomena to the decline of the Western as a genre. Anyone who was a child in the '60's can remember just how many cowboy and wild west shows were made in those days. I suspect the 1950's was probably the height of its popularity in the cinema, but I could be wrong. TV now is dominated by gritty crime shows, I suppose, and plain crap of all varieties. (Someday, a good sitcom about adults that doesn't always deal with sex will emerge again.)
Anyway, this got me thinking about the one childhood Japanese show that I can recall - The Samurai. The Wikipedia entry is relatively short, but points out that the show was very popular in Japan, Australia and the Phillipines, but was hardly shown anywhere else. How odd.
For those who can vaguely recall what the lead character Shintaro looked like, here he is:
(The picture is from a small fansite here.) Not exactly rugged good looks, but a sister-in-law of mine used to swoon over him, so she tells me.
I think most kids were most impressed by the evil ninja who jumped up backwards into trees, snuck around the houses with paper walls, and had an endless supply of throwing stars.
It would probably be seen as hopelessly violent for children today.
Pearson visits home
For a depressing first hand account about aboriginal life in his home town in Cape York, Noel Pearson's column from Saturday's Australian is worth reading.
Talk about your intractable social problems. It's also interesting to note yet again how communities as a whole faired so much better under the Christian mission system.
Talk about your intractable social problems. It's also interesting to note yet again how communities as a whole faired so much better under the Christian mission system.
Sunday, February 18, 2007
Easy global cooling?
I don't think I have seen this exact suggestion before:
Benford has a proposal that possesses the advantages of being both one of the simplest planet-cooling technologies so far suggested and being initially testable in a local context. He suggests suspension of tiny, harmless particles (sized at one-third of a micron) at about 80,000 feet up in the stratosphere. These particles could be composed of diatomaceous earth. "That's silicon dioxide, which is chemically inert, cheap as earth, and readily crushable to the size we want," Benford says. This could initially be tested, he says, over the Arctic, where warming is already considerable and where few human beings live. Arctic atmospheric circulation patterns would mostly confine the deployed particles around the North Pole. An initial experiment could occur north of 70 degrees latitude, over the Arctic Sea and outside national boundaries. "The fact that such an experiment is reversible is just as important as the fact that it's regional," says Benford.
"Benford" is Gregory Benford, the scientist/science fiction writer. A couple of years ago he was in Canberra talking up the prospects of a rotating space mirror as an engineering solution to global warming. He is evidently looking at more down to earth options now.
The quote is from Technology Review, which seems a pretty neat publication generally. What it doesn't explain is how to get the silicon dioxide up there, and how long it will stay. I thought you also were not supposed to breath the stuff (from what I recall of using diatomaceous earth in an old pool filter,) so I am not sure what is meant to happen when it comes back to earth.
Benford has a proposal that possesses the advantages of being both one of the simplest planet-cooling technologies so far suggested and being initially testable in a local context. He suggests suspension of tiny, harmless particles (sized at one-third of a micron) at about 80,000 feet up in the stratosphere. These particles could be composed of diatomaceous earth. "That's silicon dioxide, which is chemically inert, cheap as earth, and readily crushable to the size we want," Benford says. This could initially be tested, he says, over the Arctic, where warming is already considerable and where few human beings live. Arctic atmospheric circulation patterns would mostly confine the deployed particles around the North Pole. An initial experiment could occur north of 70 degrees latitude, over the Arctic Sea and outside national boundaries. "The fact that such an experiment is reversible is just as important as the fact that it's regional," says Benford.
"Benford" is Gregory Benford, the scientist/science fiction writer. A couple of years ago he was in Canberra talking up the prospects of a rotating space mirror as an engineering solution to global warming. He is evidently looking at more down to earth options now.
The quote is from Technology Review, which seems a pretty neat publication generally. What it doesn't explain is how to get the silicon dioxide up there, and how long it will stay. I thought you also were not supposed to breath the stuff (from what I recall of using diatomaceous earth in an old pool filter,) so I am not sure what is meant to happen when it comes back to earth.
Friday, February 16, 2007
The history of declining birthrates
An interesting short article here about some research looking at why women have fewer children:
Before the 1800s, children were educated at home or in church. Children became more expensive to care for and less helpful around the house once public schooling became available. At the same time, women were freed up from all-day children-rearing, allowing mothers to enter the paid labor force.
However, money isn't the only incentive for smaller families, experts say.
"We know for sure that you don't have to reach a high level of per capita income for fertility to decline, but we don't know exactly what sets it off," said historian George Atler at Indiana University. "Whether it's general change or attitudes about birth control is still a question debated among demographers today.
It's interesting, but still doesn't help answer why some Muslim countries have such high birth rates. I can't say I have ever seen much explanation of that.Who knows...
..what is going on in Antarctica? A couple of reports around today show the uncertainty about that icy pole:
First one:
A new report on climate over the world’s southernmost continent shows that temperatures during the late 20th century did not climb as had been predicted by many global climate models....
“It’s hard to see a global warming signal from the mainland of Antarctica right now,” he said. “Part of the reason is that there is a lot of variability there. It’s very hard in these polar latitudes to demonstrate a global warming signal. This is in marked contrast to the northern tip of the Antarctic Peninsula that is one of the most rapidly warming parts of the Earth.”
Bromwich says that the problem rises from several complications. The continent is vast, as large as the United States and Mexico combined. Only a small amount of detailed data is available – there are perhaps only 100 weather stations on that continent compared to the thousands spread across the U.S. and Europe. And the records that we have only date back a half-century.
The second report is about vast amounts of water under the ice:
Scientists using NASA satellites have discovered an extensive network of waterways beneath a fast-moving Antarctic ice stream that provide clues as to how "leaks" in the system impact sea level and the world's largest ice sheet. Antarctica holds about 90 percent of the world's ice and 70 percent of the world's reservoir of fresh water.
It's a very interesting place.
First one:
A new report on climate over the world’s southernmost continent shows that temperatures during the late 20th century did not climb as had been predicted by many global climate models....
“It’s hard to see a global warming signal from the mainland of Antarctica right now,” he said. “Part of the reason is that there is a lot of variability there. It’s very hard in these polar latitudes to demonstrate a global warming signal. This is in marked contrast to the northern tip of the Antarctic Peninsula that is one of the most rapidly warming parts of the Earth.”
Bromwich says that the problem rises from several complications. The continent is vast, as large as the United States and Mexico combined. Only a small amount of detailed data is available – there are perhaps only 100 weather stations on that continent compared to the thousands spread across the U.S. and Europe. And the records that we have only date back a half-century.
The second report is about vast amounts of water under the ice:
Scientists using NASA satellites have discovered an extensive network of waterways beneath a fast-moving Antarctic ice stream that provide clues as to how "leaks" in the system impact sea level and the world's largest ice sheet. Antarctica holds about 90 percent of the world's ice and 70 percent of the world's reservoir of fresh water.
It's a very interesting place.
Ranking the sharks
It turns out that Australia is not the top country for shark attacks at all, which comes as a bit of a disappointment in a way:
The number of attacks in the United States, the world’s leader, dipped slightly from 40 in 2005 to 38 in 2006; well below the 53 recorded in 2000, he said.
As in past years, Florida was the world’s shark capital, with 23 attacks, Burgess said. This was slightly higher than the 19 cases reported in 2005 but considerably lower than the annual average of 33 between 2000 and 2003, he said.
Elsewhere in the world, Burgess tracked seven attacks in Australia, four in South Africa, three in Brazil, two in the Bahamas and one each in Fiji, Guam, Mexico, New Zealand, Puerto Rico, La Reunion, Spain and Tonga.
Someone should do it on a per capita basis to get a better idea of how competitive our sharks are internationally.
The Catholics take over
The Times reports that Catholicism is becoming the most practised faith in England, due to European migration:
Figures for 2005 show that there are 4.2 million Catholics in England and Wales, under one fifth the 25 million baptised Anglicans and double the number of Muslims.
If it's anything like here, the migrants are going to have to bring their own priests with them. It will also be interesting to see if it means a more conservative Church, and a more conservative influence on politics. I certainly get the impression that the Tories have virtually given up on espousing anything much resembling social conservatism.
Average Sunday attendance of both churches stood even at nearly one million in 2005, according to the latest statistics available for England and Wales, but the attendance at Mass is expected to soar.
A Church of England spokesman said: “I don’t think you can talk in terms of decline in the Church of England. It is fairly clear that with small fluctuations the worshipping population of the Church of England is 1.7 million a month. That is actually a stable figure.”
But looking at the total numbers shows how very, very few Anglicans attend church:Figures for 2005 show that there are 4.2 million Catholics in England and Wales, under one fifth the 25 million baptised Anglicans and double the number of Muslims.
If it's anything like here, the migrants are going to have to bring their own priests with them. It will also be interesting to see if it means a more conservative Church, and a more conservative influence on politics. I certainly get the impression that the Tories have virtually given up on espousing anything much resembling social conservatism.
Thursday, February 15, 2007
On a meta-blogging note...
I find it odd that those posts which I consider most worthwhile are often the ones that attract the least comment, and do not get linked to anywhere else. It would be good if there was a simple way for readers to just mark how interesting they find a post, rather than having to comment.
Anyway, a blog like one is just as much use to myself in terms of keeping track of articles and thoughts as it is a popularity exercise. But it would be nice to have a better idea about what sort of posts I make that have the most interest to most people.
I must go over to Catallaxy and read the recent reader's analysis post. I haven't got around to that yet...
Anyway, a blog like one is just as much use to myself in terms of keeping track of articles and thoughts as it is a popularity exercise. But it would be nice to have a better idea about what sort of posts I make that have the most interest to most people.
I must go over to Catallaxy and read the recent reader's analysis post. I haven't got around to that yet...
Hitchens and Hillary
If you missed Christopher Hitchens' recent Slate article about Hillary Clinton and her credibility problems over Iraq, you should have a read.
Great moments in Council politics
If you thought soccer players could ham it up, you ain't seen nothing yet:
Some interesting energy stories
1. The anti-wind crusade of this blog continues with an article from American Spectator. (Mind you, one article there also positively welcomes global warming.) Apart from the important stuff about the difficulties of actually using the electricity they generate, here's a bit of information that surprised me:
The standard 1.5 MW structure is now 40 stories, taller than the statue of liberty. The 3 MW towers waiting in the wings are as tall as New York's Citicorp Center, the third tallest building in Manhattan.
That is big.
2. This story was in Newsweek in January, but I missed it 'til now:
The Kremlin has set about recasting Russia's once top-secret nuclear industry as the world's leading mass marketer of cheap, reliable reactors. As energy prices soar, nuclear power has been gaining in popularity, and Russia is the market leader in cut-price reactors....
"Our power stations are not a bit worse than anyone else's," says Sergei Shmatko, the president of Atomstroyexport, Russia's atomic-power-station construction company. "My dream," he adds, "is to make the export and construction of our nuclear stations as simple and as fast as putting IKEA furniture together."
3. My favourite underdog in the clean energy stakes, the Pebble Bed Reactor, continues to attract very little attention here, but in South Africa it is definitely going ahead after appeals against development approval were rejected. First demonstration plant due by 2010, and commercial modules may be available by 2013.
The standard 1.5 MW structure is now 40 stories, taller than the statue of liberty. The 3 MW towers waiting in the wings are as tall as New York's Citicorp Center, the third tallest building in Manhattan.
That is big.
2. This story was in Newsweek in January, but I missed it 'til now:
The Kremlin has set about recasting Russia's once top-secret nuclear industry as the world's leading mass marketer of cheap, reliable reactors. As energy prices soar, nuclear power has been gaining in popularity, and Russia is the market leader in cut-price reactors....
"Our power stations are not a bit worse than anyone else's," says Sergei Shmatko, the president of Atomstroyexport, Russia's atomic-power-station construction company. "My dream," he adds, "is to make the export and construction of our nuclear stations as simple and as fast as putting IKEA furniture together."
3. My favourite underdog in the clean energy stakes, the Pebble Bed Reactor, continues to attract very little attention here, but in South Africa it is definitely going ahead after appeals against development approval were rejected. First demonstration plant due by 2010, and commercial modules may be available by 2013.
The cut that might sent you mad!
A very interesting article here suggesting that there may be a connection between vasectomies and certain types of dementia.
I wonder whether such a connection might only be noticed now due to (what I presume was) the relative infrequency of the operation until about the 1970's. Is the first big wave of men who had the operation only now reaching advanced ages?
(There is also the issue of how the operation is done. From what I read, sealing both ends was popular, but appears to be associated with increased risk of long term pain as a side effect. The new trend is therefore to leave the tap open, so to speak. This was the subject of my previous post here.)
More research needed, but personally I have never liked the idea of letting one's "boys" get out into the blood stream where they don't belong.
I wonder whether such a connection might only be noticed now due to (what I presume was) the relative infrequency of the operation until about the 1970's. Is the first big wave of men who had the operation only now reaching advanced ages?
(There is also the issue of how the operation is done. From what I read, sealing both ends was popular, but appears to be associated with increased risk of long term pain as a side effect. The new trend is therefore to leave the tap open, so to speak. This was the subject of my previous post here.)
More research needed, but personally I have never liked the idea of letting one's "boys" get out into the blood stream where they don't belong.
A new type of black hole to ask CERN about, as well as "bubbles of nothing"
New Scientist notes that a new type of black hole appears theoretically possible - a "black saturn":
Actually, I had noticed the arxiv paper on this recently, but as it was not clear whether the authors thought they may be made by a particle accelerator, I did not post about it.
New Scientist notes that, as with any micro black hole, the physicists expect it will evaporate instantaneously into Hawking Radiation, but as long time readers are aware, a few credible scientists wonder whether HR really exists.
So, if a stable (non evaporating) "black saturn" is created, would its ability to absorb particles be greater that your "normal" micro black hole? How would a string of them created close together interact? Let a bunch of slow moving ones sink into the centre of the earth and what happens?
Of course, CERN's other big argument against there being any danger from micro black holes is that the moon and earth have been bombarded by cosmic rays with much higher energies for billions of years, so if they are still here any micro black holes that can be created are not planet eaters. However, as long time readers would know, there are arguments that question this analysis. (Basically, ones created at CERN may be slow moving and readily fall into the earth. Ones made by cosmic rays move fast and may zip right through most astronomical bodies)
(One day I will get around to tagging my old posts on micro black holes, but my first long article is here. For the others, a use the blog search on this page and they will all appear.)
My argument remains that CERN appears to have done a poor job at taking risk analysis seriously. They have very high expectation that HR is really the answer, even though this radiation has not been observed anywhere. (Yet it is possible that the decay debris could be observed in the Earth's atmosphere if evaporating micro black holes are being created there by cosmic ray collisions. It is just, I think, that not enough experimental work has been done yet to clearly answer the question of whether it is there.)
There is plenty of theoretical work coming out all the time that raises questions about the very nature of black holes and their decay process that should be taken into account in proper risk assessment. If CERN is actually looking at each case and coming up with good reasons why they are not a risk, even if HR does not exist, it would nice of them to tell us. Instead, it seems to just all be on a "trust us we know what we are doing" basis.
Here's one other thing I have been reading about lately: the idea of "bubbles of nothing" being created as part of black hole decay. Some of these, if I understand it correctly, could expand and be a danger. As noted in a recent arxiv paper:
Horowitz [20] has recently argued that a class of charged bubbles of nothing are a possible
decay product of black holes/strings/branes in quantum gravity. If true this would be a new,
unsuspected and disastrous endpoint of quantum black hole dynamics.
They don't explain exactly what they mean by "disastrous endpoint", but I would like to know more. (It may be that the authors of the paper think there is no danger anyway, but they do not write in anything resembling plain enough English for the layperson to understand their points.)
Has CERN looked at this work? Are there reasons to also question the "cosmic ray" analogy that I expect may also be used to argue against danger?
All question worth asking, I think, but getting answers is not easy.
Just like the central black hole, the ring would be defined by its event horizon, a boundary beyond which nothing can escape the object's gravity. The ring could be thin like a rubber band or fat like a doughnut, and the rotation would flatten it – "like a doughnut that you have squashed," says Elvang. The spinning ring would also drag space-time around with it, making the central black hole spin as well.
The black Saturn can only exist in a space with four dimensions, rather than the three we inhabit. In 3D, a black ring is impossible, so there are no big black Saturns out there for astronomers to spot – but at a microscopic level, they might really exist....
If extra dimensions exist, black Saturns might be produced in the Large Hadron Collider (LHC) particle accelerator in Geneva, due to open at the end of 2007. Because there are so many ways to make a black Saturn, with different sizes of ring and different spins, they might even be produced in greater numbers than 'ordinary' black holes.Actually, I had noticed the arxiv paper on this recently, but as it was not clear whether the authors thought they may be made by a particle accelerator, I did not post about it.
New Scientist notes that, as with any micro black hole, the physicists expect it will evaporate instantaneously into Hawking Radiation, but as long time readers are aware, a few credible scientists wonder whether HR really exists.
So, if a stable (non evaporating) "black saturn" is created, would its ability to absorb particles be greater that your "normal" micro black hole? How would a string of them created close together interact? Let a bunch of slow moving ones sink into the centre of the earth and what happens?
Of course, CERN's other big argument against there being any danger from micro black holes is that the moon and earth have been bombarded by cosmic rays with much higher energies for billions of years, so if they are still here any micro black holes that can be created are not planet eaters. However, as long time readers would know, there are arguments that question this analysis. (Basically, ones created at CERN may be slow moving and readily fall into the earth. Ones made by cosmic rays move fast and may zip right through most astronomical bodies)
(One day I will get around to tagging my old posts on micro black holes, but my first long article is here. For the others, a use the blog search on this page and they will all appear.)
My argument remains that CERN appears to have done a poor job at taking risk analysis seriously. They have very high expectation that HR is really the answer, even though this radiation has not been observed anywhere. (Yet it is possible that the decay debris could be observed in the Earth's atmosphere if evaporating micro black holes are being created there by cosmic ray collisions. It is just, I think, that not enough experimental work has been done yet to clearly answer the question of whether it is there.)
There is plenty of theoretical work coming out all the time that raises questions about the very nature of black holes and their decay process that should be taken into account in proper risk assessment. If CERN is actually looking at each case and coming up with good reasons why they are not a risk, even if HR does not exist, it would nice of them to tell us. Instead, it seems to just all be on a "trust us we know what we are doing" basis.
Here's one other thing I have been reading about lately: the idea of "bubbles of nothing" being created as part of black hole decay. Some of these, if I understand it correctly, could expand and be a danger. As noted in a recent arxiv paper:
Horowitz [20] has recently argued that a class of charged bubbles of nothing are a possible
decay product of black holes/strings/branes in quantum gravity. If true this would be a new,
unsuspected and disastrous endpoint of quantum black hole dynamics.
They don't explain exactly what they mean by "disastrous endpoint", but I would like to know more. (It may be that the authors of the paper think there is no danger anyway, but they do not write in anything resembling plain enough English for the layperson to understand their points.)
Has CERN looked at this work? Are there reasons to also question the "cosmic ray" analogy that I expect may also be used to argue against danger?
All question worth asking, I think, but getting answers is not easy.
Wednesday, February 14, 2007
Why 6 megapixels is all you'll need
While you are at the New York Times, have a look at this article explaining some tests done to see how much difference megapixels above 6 make to digital photo enlargement. Answer: most people can't tell the difference.
If a 6 megapixel camera is all that any amateur photographer really needs, and this is virtually the entry level size now, what features are the manufacturers going to come up with to entice us to keep upgrading?
If a 6 megapixel camera is all that any amateur photographer really needs, and this is virtually the entry level size now, what features are the manufacturers going to come up with to entice us to keep upgrading?
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