Science Talk

Swimming In Spacetime and Other Stories

Scientific American Editor in Chief Mariette DiChristina and staff editor Kate Wong talk about the contents of the August issue, including articles on some of the odd consequences of general relativity, life as a Neandertal, and the latest research on celiac disease. Plus, we'll test your knowledge of some recent science in the news

Scientific American Editor in Chief Mariette DiChristina and staff editor Kate Wong talk about the contents of the August issue, including articles on some of the odd consequences of general relativity, life as a Neanderthal, and the latest research on celiac disease. Plus, we'll test your knowledge of some recent science in the news.

Podcast Transcription

Steve: Welcome to Science Talk, the weekly podcast of Scientific American posted on July 31st, 2009. I'm Steve Mirsky. This week we'll look at the contents of the August issue of Scientific American magazine with Editor in Chief Mariette DiChristina and staff editor Kate Wong. Plus, we'll test your knowledge about some recent science in the news. Without any further ado, here we go; we spoke in Mariette's office.

Steve: And I'm here with Mariette DiChristina and you can see a lovely photograph of her in the Letter from the Editor column. The August issue has some fascinating stuff including the cover piece on Neandertals and Kate Wong, the author of that piece, is here, and we'll talk about that [in] a moment. We have this piece called "Adventures in Curved Spacetime" by a Brazilian physicist; what's that all about?

DiChristina: The Brazilian physicist's name is Eduardo Guéron and he is based at the, he is a math professor, based at Federal University in Brazil. And he writes the story in the tradition of [a] series of wonderful stories in the '40s by George Gamow that told the story of a physicist who had some wonderful adventures; and in this story, likewise, Guéron takes us on a journey through the wonderful adventures in curved spacetime of an astronaut, and it's kind of like a summer reading for physicists story, I would enjoy it on a beach, myself.

Steve: It's just fun reading, but all the things discussed in the article are real and necessary consequences of general relativity?

DiChristina: Right, the largest scientific point here Steve, is that 90 years after Einstein described how, you know, gravity comes as a consequence of curved spacetime—and we should back up on that for just a minute. You know, for instance around Earth, you can think of gravity as forming a kind of a well around Earth, which causes the things that pass near Earth, the moon I would say, which is orbiting on its path, to stay within the vicinity because it falls into that gravity well, metaphorically speaking; and in likewise the same way this astronaut that is fictitiously described by our good mathematics professor takes a journey through curved spacetime. He leaves his spacecraft—and again this is all based on the latest research—he jets off and tries to form a triangle; he brings a laser pointer with him, so he knows he is traveling in a straight line, and also some shaving cream and he realizes when he measures that…

Steve: Not to shave with.

DiChristina: Not to shave but to mark his path, thank you; and he realizes when he measures that triangle that it adds up to more than 180 degrees.

Steve: And the astronaut finds out, and this is real, that if you needed to, in curved spacetime, if you needed to move in the vacuum you could do so without anything to push off of or any kind of accelerant to force you by virtue of Newton's third law, you can just by twisting your body, by moving your body in the right way, you can actually move from point A to point B in this empty space as long as it is curved space.

DiChristina: Right, as long as it's curved space. Now this comes from a, this piece of it comes from a 2003 paper by a planetary scientist named Jack Wisdom at the Massachusetts Institute of Technology; and what he discovered is that you can move, as you [were describing] through curved space by moving, [let's] say, your arms and legs, or if you're an alien as it is described in the article, a tripod alien—just for the simplicity of demonstrating how the movements are with, sort of, heavy feet and a ball at the end of the tail that helped to move the [weight] around, just to make it kind of simple to look through—you can move through curved spacetime without pushing against anything, and this is the key here. To get an understanding of the basic concept, think about sometime maybe when you sat a soda pop shop or a bar or something on one of those chairs that's on a swivel wheel. And if you were to swing your arms around, your body would start to move in [opposition] to that, and moving through curved spacetime is similar in this fashion. You know, it's not exactly similar because, you know, curved spacetime being without immediate gravity, you know, without things to push against, whereas you are resting on a chair and pushing, so it's really just an analogy. But if you [were to] move your arms in and out you could quickly spin your body. Or imagine a cat falling from a one-story building, let's say, snapping it's legs out and around and back so that it can land on its feet; it too is moving through space without pushing against anything. In a likewise fashion, Jack Wisdom's paper described how one could "swim" through curved spacetime.

Steve: You can't swim fast; it's not going to help you if you're couple of miles away from your ship. But if you're, you know just for argument['s] sake, if you are 20 feet from the ship, but you're in the same, going exactly the same velocity as the ship, ordinarily well, you would be up the creek, so to speak; because with nothing to accelerate against you would just parallel the path of the ship until you run out of oxygen or starve to death, whatever. But with the implications of general relativity you could very slowly and laboriously make your way back to the ship and, you know, get back inside and survive. And the other really fascinating implication of general relativity is that falling through a vacuum in curved spacetime by stretching and contracting but not at the same rate, if you stretch at one rate and contract at another rate, you can actually slow your descent and behave like a glider even though there is no atmosphere.

DiChristina: Right you're describing the gliding part of the story, which is based on Professor Guéron's own research with another fellow, Ricardo Mosna at the State University of Campinas in Brazil, and that's from a 2007 paper, and yes, you can glide. An object could—approaching a planet—could slow it's descent by moving as you described, contracting at one speed, expanding at another, and this too is a specific consequence from the theory of general relativity.

Steve: Mariette, it's really fun stuff and it's illustrated with kind of cartoony like images, certainly looks like Archie in space, actually just a little bit—I don't see Jughead; I think he died in the airlock. Oh! Then, well, there's a little green alien there.

DiChristina: He does have a lovely sidekick, who has those incredible limbs I was telling you about, all the better to describe the principles behind this. It's a fun article but it's serious physics and based on the latest research, and I hope everybody enjoys it.

Steve: And we also have the cover piece, speaking of fun articles that are based on serious things, [which] is about our closest relatives to the human beings to, well, they are human beings too, well to Homo sapiens—the Neandertals and the author Kate Wong, who is a staff editor here at Scientific American and a real expert on this stuff is with us. How are you doing, Kate?

Wong: Doing really well, Steve, thanks.

Steve: So, this is a fascinating article because we are really, we are still learning so much about Neandertals. I swear I saw one on the subway today, but apparently that's impossible.

Wong: That's right. So far as we know, the very last Neandertals died out shortly after 28,000 years ago. Scientists have known about Neandertals since the 1800s, so if you look at the extinct humans in the human family tree, they know more about Neandertals than any other of the extinct species; and that being said, there are still really mysterious to us in very many ways.

DiChristina: One of the things about Neandertals that I find so intriguing is that they were around our size and shape, maybe a little bit more massive in their arms and legs but roughly our height, maybe a few inches shorter; if a Neandertal did walk past you on the subway, you might not have noticed him.

Steve: Is that really true though? I have heard that if a real Neandertal happened into the room, you would jump back because their physical appearance would be so strange to you that you'd really be taken aback.

Wong: It really depends on who you ask. There are certainly a number of scientists who minimize the physical differences between Neandertals and modern humans and those who, as you said, would very readily picture an extremely different creature from us.

Steve: We have [here] an interesting illustration, an artist's scientifically informed idea, of what a Neandertalmight look like and it's close enough that you might give the guy a second look but you probably wouldn't run screaming.

Wong: Yeah, the basic physical differences or the most noticeable physical differences between Neandertals and modern humans are, like, that Neandertals are, they are within the height range of modern humans but on the shorter side, so maybe five and one half feet tall or so. But they were massive. They had big barrel chest[s] and short, stocky limbs. They were really built for power and they were also built to retain heat in the cold climate that they often endured. And as far as their faces go, they had really massive browridges over their eyes, and they did not have chins really, so their faces would have looked different, but maybe dressed with a suit and a top hat they would not look so different.

Steve: One of the things that you talk about—I am just laughing at the idea of [a] Neandertalin a suit and a top hat, [a] little like Young Frankenstein.

DiChristina: I was thinking.

Steve: Like Peter Boyle [in] Young Frankenstein. For you kids out there, I am seeing you rush out to see it immediately. So the Neandertal browridge you mentioned in the article. It was probably, and I had never seen this before, it was probably a consequence just of genetic drift rather than any kind of real selection pressure. Can you explain that a little bit?

Wong: Yeah, there is no known functional benefit to having that brow, at least none that has been established with certainty. So what a number of scientists proposed is that feature is really the result of genetic drift within their narrow population and not something that benefited them in any particular way.

Steve: Genetic drift refers to the fact that just by chance, some small percentage of Neandertals had this prominent ridge and then they became the progenitors of the population so it got passed on even though there was not any particular selection pressure, any particular survival advantage, to having it.

Wong: That's right.

Steve: So, what are some of the things that are just becoming known about Neandertals? We talked about their body size and the heat, possible advantage; but things, like, what's the major differences between Homo sapiens and the Neandertals, I realize that there is still a lot of disagreement in the scientific community about this, but what do they think were some of the differences? Culture is really a major difference between the two human species.

Wong: Yes and no. I mean there were for a long time, for many decades, scientists believe that Neandertals were fundamentally different from modern humans in the way that they behaved. And when you look at the archeological record, what you see are beautifully made stone tools, but not very many cases of Neandertals making jewelry; no instances of Neandertals making musical instruments or painting on cave walls. And so there seems to be a difference, although there are certain, a few cases of Neandertals making jewelry and other seemingly symbolic artifacts. But they don't seem to have done it with a regularity that early modern humans did.

Steve: And we've also discovered, because we now have some actual NeandertalDNA to work with, that they did have this particular gene, FOXP2 gene, that is correlated with our ability to speak, not that I'm a good example of [that] right at the moment. But species that do not have this—and that's pretty much everybody else—can't really articulate. But the FOXP2 gene seems to be really important if you're going to have spoken language, spoken communication. And for a long time it was thought that the Neandertals didn't have ability to communicate orally in a sophisticated way. But now we know that [they] did have [the] FOXP2 gene, which implies that they probably could speak to each other pretty well.

Wong: It implies that they had a similar ability to form words; it doesn't tell us anything about language, which is much more [than] the mechanical ability to form words. So, yes, it does forge maybe a stronger bond between Neandertals and modern humans when we're looking at the genetics; and yet at the same time, there seem to be a number of distinctions between Neandertal DNA and modern human DNA. We don't know the full picture of that. We'll have [a] better sense of it when the rough draft of the Neandertal genome is published, which is supposed to happen later this year. But for now, the genetics, and even when the genome is published, we still won't know, because so much of the human genome, we don't know what it means functionally; that holds true for modern humans, so of course, it's not going to instantly tell us everything that we want to know about Neandertals.

Steve: And one of the things in the article is it looks like [the] metabolic requirements, because of their particular physiology, were significantly higher than modern humans. It looks like they needed anywhere from, what was it, 100 to 350 more calories a day, and that might not sound like much to us in our potato chip–laden world, where we can just, you know—and unfortunately do—pick up an extra 400 or 500 calories anytime we feel like it, but that could be a huge problem for somebody who's really, you know, living hand to mouth, just wondering where the next meal is going to come from everyday.

Wong: Absolutely! It could really a deal breaker if you think about how hard it was to live under really cold conditions, colder than anything that our species today has to contend with; and then on top of that making your living essentially, as an ambush hunter of what seems to be mostly large, dangerous animals like woolly rhinoceroses, then that extra 150 to 300 calories a day, yeah, that's a big deal. That can determine whether or not you survive or perish.

Steve: And the article mentions that there is no for evidence of sewing in Neandertals, so although their bodies were really good at maintaining heat or conserving heat, they probably weren't as good as modern humans at making clothes that could help with the heat conservation.

Wong: It's really hard to know. There's lots of ways to attach pieces of hide. It doesn't have to involve needles. But what we can say is that although modern humans have left behind what are clearly awls and needles, Neanderthals did not leave those things behind. They may have been made out of more perishable materials, wood—maybe it was fire treated for hardness or something; we don't have it anymore, but who knows? But clearly though they had to have to made clothing to withstand the cold temperatures that they experienced.

Steve: There's no end of people still out there looking for Neandertal artifacts and Neandertal fossils.

Wong: Yeah, absolutely. There is a lot of active research in terms of archeologists going out there and looking for Neandertalbones and their artifacts and of course the genome opens up a whole new range of possibilities for what we can extract about Neandertallives.

Steve: There's lots of other interesting stuff in the magazine. There's an article celiac disease. On first glance, it seemed like, well, what's an article on you know, one particular disease [doing] in Scientific American, because we don't really don't do just, you know, disease of the month or whatever. But the celiac article illustrates larger points related autoimmunity.

DiChristina: Yes, it does. Actually before I speak about that, I would like to back up for just a minute. In Kate's discussion about Neandertals and our own history as a species on the planet, reminds me of the origin of the celiac disease issue which is, you know, very deeply tied with our human history. One day, way back when, various early humans realized that from seeds, spring plants and those plants provide us with food. And so herein lies the wonderful benefit to humanity of figuring out a way to make settlements rather than having to gather all your food or necessarily hunt every piece of meat you eat. So we began to plant these seeds and began to grow them, began to eat, be better fed and more healthy and promptly contributed to us living longer in short order; although it certainly raised other problems, as well. And among those other problems, was the problem of celiac disease. Celiac is triggered partly by the ingestion of gluten or protein common in wheat. There also a couple of factors that you need to have, as well: You need to have the genetic susceptibility, and you need to have something called a leaky gut, which you can think of as the ability for the intestine to let through this gluten protein into the bloodstream, where it can incite the activity of the immune system and thus create this autoimmune problem. Because what is autoimmune disease? It is a disease where the body is acting against itself, where our immune system, which is normally harnessed for our protection, is instead causing us troubles of one kind or another. In celiac disease, people who do suffer from it, suffer chronic indigestional problems—they have bloating, they have diarrhea, they have, you know, all sorts of various discomforts related to that, and it's all key to this susceptibility.

Steve: It's really interesting, it gets down to basic chemistry because there are proteins in wheat gluten that have certain amino acids in them that the celiac sufferer's digestive system can't chop up the proteins into small enough bits. And so you have these longer bits of these particular amino acids, and they're the things that really confound the lining of the intestine.

DiChristina: Yeah, a couple of things here. You know, [one] is, first of all celiac also expresses itself with other problems, for instance, absorbing iron [and]. you know, other immune deficiencies that result from it. Another is you do need these three factors: that genetic susceptibility, the problem with the gut and the gluten ingestion to trigger it. What happens is these finger like protrusions in the intestine, they're called villi, and you could think of them as looking like fingers; and they get both, really inflamed and then can't absorb the nutrients and pass them, convey them along to the bloodstream for distribution in celiac disease.

Steve: What we're finding out based on studying celiac though it has implications for all our autoimmune diseases.

DiChristina: Well, for many. I'm glad you're looping us back to what you had raised at the beginning. Some of the diseases that are autoimmune types are related to celiac. And so things, in other words, things we find out about how to block celiac disease or how to treat it would be applicable potentially to these diseases, [such as] type1 diabetes, rheumatoid arthritis, multiple sclerosis and inflammatory bowel syndrome. All of these share characteristics of celiac disease, such as that leaky gut.

Steve: What are the nuts and bolts of the potential treatments? What are we learning from celiac that could specifically be applied to this wide range of autoimmune conditions?

DiChristina: One thing that was really, kind of, key for the researchers is the leaky gut itself. I mean, the researcher describes how for a long time, it was thought that there was a kind of grout that held the intestinal wall together really firmly and there was no reason, it wasn't scientifically interesting. But as they were trying to develop a particular vaccine that would have taken advantage of that, they found that the people who took the vaccine got horrible diarrhea, and it was a counter indication for using that vaccine. In other words, as the poor researcher said, it's the low light of his career. All years of his research had literally gone down the toilet. But what it did, as it so often happens in science is, spark him to a new idea. Well, maybe this area of the intestinal wall was interesting to take a look at, and maybe through there they could get some keys from something else, and that's how they got started. So, eventually they homed in on a particular kind of protein called zonulin, which is involved somehow in managing or manipulating the lining of, you know, the permeability of that intestinal wall. Now, we don't know all the things zonulin does yet, it probably does many things in the body, probably it is active in many processes; but this one seems like it may potentially be a key to therapies or one of the keys to therapies for celiac disease.

Steve: As well as we can probably extend to whatever we learn here, you know, we learnt something studying this autoimmune condition, and we might wind up using it in some other autoimmune conditions.

DiChristina: Right and something I didn't mention before Steve, but which I think is important to mention here is, even in focusing on a single disease—and you're right, we don't typically do that, at Scientific American, we don't want to do "disease of the month" per se, although certainly we don't mean belittle the importance of, you know, these various diseases in people's lives, but at the broader context as well. In this case, celiac disease, affects a surprising number of people; it's about 1 percent of the population worldwide, and in the U.S. that translates to around 2 million people. About 100 years ago, there was a fellow who discovered there was a disorder of chronic indigestion, but in those days, they had no idea what it was from. It was only in the past several decades that we realized that it's a particular disorder called celiac disease, and that it has a particular characteristics to, you know, the way the disease presents itself, and also that it can be at least managed, if not perfectly, through changes in diet although, as everybody knows very difficult to completely avoid clearly. Thank goodness, there are many more products and a lot more awareness of the problem these days, so it's a little bit easier for folks.

Steve: Yeah, in the last 10 years, I think, you've seen this explosion of gluten-free products out there because it's become recognized just how pervasive celiac is.

DiChristina: Right and for many people also—and this is true of a friend of mine as well, [my old] journalism professor, in fact—people maybe go through a lot of their lives because of their lack of understanding of celiac and only when they're adults, sometimes into, you know, middle age are they finally finding out that all their reason their stomach was tricky was celiac all along.

Steve: Lots of other interesting stuff in the issue. Yucca Mountain and how our politics is changing that whole scene there about nuclear wastes storage. Remember high temperature, superconductivity which has, sort of, been out at the headlines for awhile now. But recent discoveries about the possible role of iron, which is not an element that you usually associate with superconductivity, could wind up playing a big part in the development of new superconductors. And let's finish up with the you know, one of my favorite features in the magazine "50, 100, 150 Years Ago"; and I'd like to read both of you, you've seen this before, but it's been a while since the August issue was lying around here in page proofs. So I'm going to read you from August of 1909, Scientific American, 100 years ago, this issue.

Mr. Ernest Ruhmer, of Berlin, well-known for his inventions in the field of wireless telephony and telegraphy, has succeeded in perfecting what is probably the first demonstration apparatus which may be said actually to solve the problem of tele-vision (and "television" is spelled "tele-vision" in 1909). The writer has had an opportunity of inspecting this curious machine immediately before it's being sent to Brussels, in order there to be demonstrated before the promoters of the Universal Exhibition planned for next year. In fact, a complete and definite tele-vision apparatus, costing the trifling sum of one and a quarter million dollars, is to be the clou of this exposition.

A million and a quarter for a new TV; and now, you know, with a, you can carry one around in your pocket.

DiChristina: So today, right, just for a few hundred dollars and a decent antenna, we have this thing, which no longer is hyphenated, television, which provides crystal-clear digital pictures of what, you know, they're almost look like looking at a window today, it's quite remarkable; the transition that can be made in just a hundred short years.

Steve: What did they do at night without? Well, I mean, obviously there was at least one TV, but at a million and a quarter, only the very richest people could watch it and what was on? You know (laughs), some guy reading the news.

DiChristina: I would think, right, they would crack open the Dickens and get going with Bleak House.


Steve: Now it's time to play TOTALL……. Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL……. Y BOGUS.

Story number 1: Speaking of Neandertals, an investigation has fingered a Homo sapiens in the death of a Neandertal, based on the type of stone point found in the Neandertal's 50,000 year old body.

Story number 2: Shark attacks are scary—bom-bom-bom-bom-bom-bom—but people kill four orders of magnitude more sharks than sharks kill people.

Story number 3: The human body often emits visible light.

And story number 4: People synchronize their blinking when watching a video.

Time is up.

Story number 1 is true. It looks like the modern human offed the Neandertal with the kind of stone point Neandertals, couldn't come up with; that's what the report in the Journal of Human Evolution says. For more info, check out Kate Wong's July 30th article on our Web site entitled, "Homo Sapiens Fingered in Neandertal Cold Case".

Story number 4 is true. A small study found that people did sync their blinking while watching an action packed video; it was [a] Mr. Bean sketch, actually. This synched blinking probably means that we time our blinks based on the action to best ensure that we don't miss anything important. For more, check out the July 31st edition of the daily SciAm podcast, 60-Second Science.

Story number 3 is true. The body does admit measurable visible light, but you don't notice it because it's at very low levels and everything else is usually so well lit. The emitted light is related to metabolism, so future cameras might be able to spot problems related to metabolic conditions. The research appears in the journal Public Library of Science ONE.

All of which means that story number 2 about, people killing four orders of magnitude or 10,000 times the numbers of sharks than sharks kill people is TOTALL……. Y BOGUS. Because what is true is that people kill on the order of 10 million times as many sharks every year [as] sharks kill humans. For example, in 2008 59 recorded shark attacks resulted in four human deaths; meanwhile humans killed some 73 million sharks last year, mostly for their fins to make soup. Why not just leave the sharks alone [and have the minestrone.]

Well, that's it for this episode of Science Talk. Check out for the latest science news and for Michael Shermer's Skeptic column about who really wrote the works of Shakespeare—it was Shakespeare. For Science Talk, I'm Steve Mirsky, thanks for clicking on us.

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