科学美国人60秒 SSS Cosmic ray threat, sasquatch DNA, geochemist cook

（单词翻译）

Welcome to the Scientific American podcast for the seven days starting March 1st. I am Steve Mirsky. This week on the podcast, legendary¹ astrophysicist Eugene Parker talks about a big problem with sending people to Mars. Geneticist Dave Coltman discusses the DNA³ analysis he did on a very unusual tissue sample and geochemist Don Siegel feeds us the inside story on his new book. Plus, we will test your knowledge of some recent science in the news.

First up, University of Chicago professor emeritus⁴ Eugene Parker. Almost 50 years ago he gave us a comprehensive explanation for the solar wind, the constant stream of charged particles coming at us from the sun. In the March issue of Scientific American he explains that astronauts going on a trip to Mars have a bigger, tougher problem than the aliens or asteroids⁵ of science fiction. I called Parker at his home in Chicago.

Steve: Dr. Parker—thanks for talking to me today.

Parker: Oh, you are quite welcome; my pleasure.

Steve: So, you have this article in Scientific American in the March issue called "Shielding Space Travelers" and it's kind of cold water in the face for sci-fi fans.

Parker: I am afraid so. I was a little disappointed myself on where the facts lead you.

Steve: So, the big problem—we are talking specifically about a trip between Earth and Mars although this problem would come up in any kind of a trip outside the atmosphere, right?

Parker: That's right! A moon base for instance would have this problem.

Steve: Well! Let's talk about the problem, because I haven't really explained that. The problem has to do with bombardment by cosmic rays.

Parker: Yeah!

Steve: What are cosmic rays, first of all, and why are they a problem for people?

Parker: Well! The cosmic rays are mostly protons—i.e., the nucleus⁶ of a hydrogen atom with a few nuclei⁷ of heavier atoms thrown in. They are moving nearly the speed of light so that when they hit some matter they go right on through leaving behind a trail of atoms with electrons ripped off them and chemical bonds broken. While we are biological organisms made up of complicated molecules⁸ and chemistry, and this just does enough damage that it's unhealthy if you get a very intense dose, you can be sick just from the fact that there is so much damage right at that moment; if you get a less intense dose, something spread out over more times then it breaks a lot of DNA, too, and even though you might not feel sick, the accumulation of broken DNA is not good. You tend to be prone⁹ to cancer in later years and so forth¹⁰.

Steve: People on the surface of the Earth really don't have to worry about this too much, right?

Parker: That's correct. The atmosphere over your head is 14 pounds of air over every square inch—or a kilogram over every square centimeter—and that's enough to stop almost all of the cosmic rays.

Steve: In your Scientific American article in the March issue you talk about the three most common proposals that people have put forth in an attempt to come up with solutions to this problem and the three proposals to shield space travelers and you pretty much take each one apart. Let's go through them. The first proposal that people put forth to protect travelers is to surround the ship or to surround the individuals on the ship with some kind of matter that will take the hits of the cosmic rays.

Parker: Yes!

Steve: So, what’s the problem with that one?

Parker: The problem is very simple. It takes too much matter. You would never get it off the ground. The best design that I know was put together by some experts who were convened¹¹ at Marshall Space Flight Center for a few days to sort of think it through. You want to use matter that has a lot of hydrogen in it—the protons—that's the most efficient use of a matter. They suggested polyethylene because it's a solid—you don't have to build a tank to hold it and the minimum weight was 400 tons. In principle, yeah you could do it, but the costs get out of this world.

Steve: Literally¹². (laughs) So, the second proposal that people put forth is to put a magnetic field around the ship to deflect¹³ the positively¹⁴ charged ions; and what's the problem with that one?

Parker: Well! Essentially¹⁵ you are imitating the Earth, but on a small scale; and because it is a small scale you must use a very intense seal. It's the product of the dimensions of the field times the strength of the field that gives you a measure of the deflection; and so you need something like 200,000 gauss—that's about 400,000 times more intense than the magnetic field of our Earth—and it's clear you would have to use a superconducting magnet—i.e., a magnet in which the current-carrying wires were super conductors. And Professor Sam Ting at M.I.T. got his group together—they have had a lot of experience with superconducting magnets and high-energy physics experiments, so, the technology is pretty well known—and they came up with a design which would go for a [forty] nine times [tons]. And again you can lift this off the surface of Earth, but putting it down on Mars and bringing it back again, again it gets to be difficult and that is to say expensive.

Steve: Right!

Parker: And then there is the problem, too—the effects of strong magnetic fields on a person living within the field are not known.

Steve: So, we might be replacing one health problem with another health problem?

Parker: You might, yes!

Steve: So, the third proposal is give the entire spacecraft a positive charge to repel¹⁶ the positively charged ions coming at it; and what's the problem with that?

Parker: What people forget is the space is not empty. Space at the orbit of Earth has about five electrons and five protons per cubic centimeter. Those electrons would just love to see two billion volts¹⁷ positive. They would come ramming¹⁸ in like cosmic rays.

Steve: Maybe there are biological solutions that we don't know about yet where potential space travelers could take some kind of a treatment in advance that would stop the damage from happening or maybe you will just find people who are willing to do it anyway.

Parker: The data that are used to proclaim what is safe and what is not safe come from people who have accidentally received a burst of radiation in a laboratory accident or have been subjected in Japan to a nuclear bomb—and they got a big dose over a very short period of time and the assumption is that it's the total dose that counts. Now, that might not be true. It might be that if you got a low level as—such as you would from cosmic rays spread out over a couple of years—that your body could repair some of that damage over the period of time and you would not suffer so much as if you had gotten the whole thing in a relatively¹⁹ short period of time. That is conjecture²⁰. Nobody knows to what extent that would improve the situation.

Steve: Well! Dr. Parker, it's been a pleasure to talk to you. The news isn't good, but it's good to talk to you anyway.

Parker: Well! It's nice to talk to you and I hope the future brings more hope.

Steve: There's a lot more on this subject in Eugene Parker's article called "Shielding Space Travelers". It's in the March issue of Scientific American available for purchase at newsstands and at our Web site, www.sciam.com; [that's] www.s-c-i-a-m.com.

Now it's time to play TOTALL…….Y BOGUS. Here are four science stories; three are true. See if you can figure out which one is TOTALL…….Y BOGUS.

Story number 1: The ivory-billed woodpecker was thought to be extinct, but last spring, ornithologists reported that they found one of the birds living in Arkansas. Now, a research team reports that over 100 of the woodpeckers have been quietly living on the private Arkansas estate of the Walton family the owners of the Wal-Mart store chain.

Story number 2 is from the behavioral psychology²¹ files. A group in New Zealand was upset about the content of an episode of South Park that was scheduled to run in February. Doesn't matter what group, all outraged²² groups pretty much make the same mistake: They mount a publicity²³ campaign to urge people not to watch the show and so, when the South Park episode ran in New Zealand, it drew six times its normal audience.

Story number 3: Researchers found that their quantum computer gave them meaningful data by not running the program.

Story number 4: The Discovery Health Channel is running this double feature in March Half-Ton Man, followed by 750-Pound Man.

We will be back with the answer. But first, call it CSI: Sasquatch. show on, well close, Dave Coltman is a geneticist at the University of Alberta. He heard about a Sasquatch sighting in the Yukon that included the recovery of some alleged²⁴ actual Sasquatch hair. So, Coltman put his big foot down and offered to analyze²⁵ the DNA. If you are ready to hear about the results of that test, here's what Coltman said when I called him at his office in Alberta.

Steve: Professor Coltman, thanks for talking to me today.

Coltman: No problem.

Steve: Tell me about how you wound up doing a DNA sequence analysis of what was allegedly a Sasquatch.

Coltman: Well! It was last summer—July—and I was watching the news and there was a Sasquatch sighting in the Yukon that had really sort of taken the imagination of the media. It was on the CBC, it was on television; and these people who had seen the Sasquatch over their backyard had actually found hair and footprints the next morning and they sent the hair to the regional biologist in the Yukon. I happened to know, I have done some work with biologists in Yukon before and I think one of the media asked them if they would be able to do a DNA test, but they didn't have the resources to do that. So, that evening I—on a whim²⁶ almost—sent an e-mail and said just send that hair down to our lab here and we will test it for you because we do a lot of DNA work from hair and other kinds of samples. So, it was quite a straightforward²⁷ thing for us to test and I though[t] well, kind of on a whim; and also maybe to help them out so that he could be absolutely certain that what it was and to satisfy curiosity of the public by we running this test on.

Steve: So, this was more of an exclusionary²⁸ test? You didn't think it was going to be a Sasquatch?

Coltman: (laughs) Well! We were 99.9 percent sure, but there [is] always a shadow of doubt.

Steve: Right! Because being a good scientist you left open the possibility that it was a Sasquatch.

Coltman: Of course, you have to do that. You never accept anything as being absolutely true. We work in the other direction since we try to rule out the things that we can disprove. And what I was really thinking about [is that] this is a good story to tell high-school students to get them interested in DNA profiling; and the fact that, you know, the CSI is on television, but in fact we do stuff like this pretty routinely all the time. So, that thought was one of my motivations.

Steve: So, you get the sample.

Coltman: We get the sample and my technician handled it, Dr. Corey Davis, and he extracted DNA from the follicles of the root of the hair. It was quite a large sample, quite a large clump²⁹ of brown, wooly³⁰ hair. So, it should have been a good source for DNA. You need the follicles—it's usually where you get the best DNA from. And, he extracted DNA and amplified³¹ a gene² fragment from the mitochondria and then determined³² its DNA sequence.

Steve: And the sequence analysis showed you what?

Coltman: Well! What we do is—if we have a sequence from an organism the first time we have seen it before or some organisms we didn't know—what we do is we align³³ the sequence to all of the known sequences in the international DNA databases; so everybody who is sequencing DNA for any reason would submit their sequence to this center holding (unclear) called [the] gene bank. So, we tested it against that database to find out what it would match and this was something [where] you quite literally cut and paste the sequence into your browser³⁴ on the Web and it will return with the best matches; and it came back with 100 percent matches to a bison. So, we were pretty sure we had a bison.

Steve: Now, how disappointing.

Coltman: (laughs) Yes! it was, but in hindsight, I mean, I think we were actually quite relieved that we got a DNA sequence from this hair at all. It was really tough to get DNA out of this specimen³⁵, which in itself tells us something. Normally if we pick up a hair like what is snagged on a tree in the field—or, you know, anywhere—and it has a visible follicle, it's very easy to get a DNA profile from that; we will never have any trouble. But in this case Corey had to try over and over again and every trick in the book and finally he got a DNA profile from that. So, there is something suspicious about this hair—either it had been outside for long time or maybe it had come from a rug or a coat that had been tanned, because that tampers³⁶ or destroys DNA.

Steve: So, you suspect that someone might have been running around the forest wearing a bison skin rug and masquerading as a Sasquatch?

Coltman: Yes! That's indeed one possibility; or it blew there along the wind; or, you know, a bison went through their backyard.

Steve: If there was a real Sasquatch out there what would you expect its DNA sequence to most closely match?

Coltman: Right! Well! I think conventional wisdom, if you like, has that Sasquatch is probably a primate³⁷, so, in which case I think we would find a very high similarity between that sequence and probably human or any other hominoid primates³⁸ that walk upright. So, my guess is that we would find a close match to primates and particularly close match to human, but not a 100 percent match.

Steve: Well! Thank you very much Professor Coltman.

Coltman: You are welcome.

Steve: Professor Coltman's paper appeared in the February issue of Trends in Ecology and Evolution; the title is "Molecular³⁹ Cryptozoology Meets the Sasquatch" and it's available online. The Web site address is nasty, so just Google Coltman, c-o-l-t-m-a-n, and the word trends and it comes up in the first page of results that you will get.

Now it's time to find out which story was TOTALL…….Y BOGUS. Let's review the four stories, three of which are real.

Story number 1: Ivory-billed woodpeckers have been living with the Waltons.

Story number 2: Urging New Zealanders not to watch South Park had the opposite effect.

Story number 3: A quantum computer works by not running.

And story number 4: A Discovery Health channel double feature is Half-Ton Man, followed by 750-Pound Man.

May I have the envelope please? The usual audience for South Park in New Zealand is about 32,000 people. After being urged not to watch, 210,000 people tuned⁴⁰ in. (Well, what a terrific audience.) Yes, the weird⁴¹ world of quantum mechanics means that the computer gives a meaningful answer even when you don't run the program. (Ensure the cat is sleeping on top of the CPU; we are not sleeping). Anyway you can get the details in the February 23rd issue of the journal Nature. (I am the arsenal⁴² four thousand). The Discovery Health channel is running the 1,750-pound double feature on March 5th, according to their Web site. Well! Listen you don't lead with a half-ton man and then follow up with a 750-pound man; you wouldn't start a sci-fi double feature with Tthe Thing and then follow it with a somewhat smaller Thing. (I learnt something today.)

Which means that the story about the ivory-billed woodpeckers is TOTALL…….Y BOGUS; which is just as well because nobody needs a big sale on ivory bills at Wal-Mart. (Attention shoppers.)

Next up, Syracuse University geochemist and hydrogeologist Don Siegel. He has a new book out, and though it is technically⁴³ about chemistry, you will have to use your needle to sew the connection. I called Siegel at his office in Syracuse, New York.

Steve: Professor Siegel, good to talk to you today.

Siegel: Yeah! Good morning to you.

Steve: Tell me about your work in general—what you study. And I know that you recently won the Meinzer Award, a very prestigious⁴⁴ award in your field. What was that for?

Siegel: Yes! I am a hydrogeologist and a geochemist. I study the fate and transport of contaminants in groundwater. I study water resources and I study issues related to global change. So, recently I was delighted to have won the Meinzer Award from the Geological Society of America. And this is an award given for making fundamental discoveries in hydrogeology. So, my colleagues decided⁴⁵ that the number of papers I wrote 20 years ago have made impact—takes a while sometimes—and these papers related to how glaciers⁴⁶ 10,000 years ago pumped fresh water into otherwise, dirty acrophores, hence, in a sense, cleaning them up. So now we have potable water and couple of other papers related to how methane⁴⁷ gas is generated in peat lands and how peat-lands growth is related to groundwater hydrology.

Steve: It sounds like very interesting work and very topical, but you are also the author of a new book.

Siegel: Yes! I am an author of a Kosher Chinese cookbook.

Steve: And it's called?

Siegel: It's called From Lokshen to Lo Mein. Lokshen is the Yiddish word for egg noodles and lo mein of course is a Chinese noodle.

Steve: So, the question then is what's a nice Jewish geochemist like you doing writing a book on Chinese cooking?

Siegel: Well! I have always had a passion for cooking in general and during the past 15 years or so, I have been catering⁴⁸ very large Chinese banquets for Jewish fund-raising organizations here in upstate New York; and there has always been a connection between Jews and Chinese food. A lot of people realize that on Christmas many Chinese restaurants stay open in order to serve their Jewish clientele.

Steve: On the back of your book is a quote from a professor Chen Zhu who is a colleague of yours.

Siegel: Yes!

Steve: And he says "he proves"—he being you—"he proves my longtime belief that a good geochemist must be a good cook first." Is that true?

Siegel: Oh, I think so. Many of my geochemist friends are good cooks and the process is pretty similar. If you are a chemist, you go in the lab and you mix reagents and then you get reactions going and products coming out of your reaction. In cooking it's the same kind of thing where you mix all these ingredients, watch reactions proceed, and then when a product comes out, the only difference is that in my geochemistry it takes six months to years before I figure out if I am right or wrong, but when I do my chemistry in the kitchen, I determine upon[if I'm] right fairly quickly.

Steve: The taste test.

Siegel: The taste test, that's right.

Steve: It must be nice to have some more instant gratification for a change.

Siegel: I am really big on instant gratification. (laughs)

Steve: It's [often] tough to get that doing scientific research.

Siegel: That's right! It took me 20 years, right. (laughs)

Steve: There's a very cute story in the book. I should say that about the first 30 or 35 pages in the book are narrative⁴⁹ and then you have a lot of recipes.

Siegel: Right!

Steve: There's a cute story in the book about another colleague of yours, who got married. You want to tell that story?

Siegel: Yes! there was a colleague of mine here at Syracuse University, Wu-Teh Hsiang, and Wu-Teh married a Jewish woman, Marjory Baruch from the famous financier family. She is a friend of our family and so Wu-Teh converted to Judaism and then when he was introduced to Marjory’s family he met one of the great aunts, one of the big people in her family and so the great aunt looked him up and down, said, you must like Chinese food; and then Wu-Teh responded immediately saying, but of course—I am Jewish.

Steve: That's great. (laughs) That's a great story. You are going to be out on tour with your book?

Siegel: Yes! I have been on tour and I have gone from LA to New York and from Detroit to San Antonio doing food shows and book signings and discussions, and I will be in Scotch⁵⁰ Plains, New Jersey⁵¹ on March 9th.

Steve: And how can people find out about that appearance?

Siegel: They can find out the details from my Web site if they want. It's www.kosherchinesecooking—one word—.com.

Steve: Great to talk to you today. Thanks very much.

Siegel: Nice talking to you Steve.

Steve: Well! That's it for this edition of the Scientific American podcast. Our e-mail address is [email protected]; that's [email protected]. And also remember that science news is updated daily on the Scientific American Web site, www.sciam.com; www.s-c-i-a-m.com. I am Steve Mirsky. Thanks for clicking on us.