Podcast Transcription

Steve: Welcome back for part 2 of our podcast of the press conference with cosmologists Lawrence Krauss, Alan Guth, John Carlstrom and Scott Dodelson, which took place on February 16th in Chicago at the annual meeting of the American Association for the Advancement of Science. In part 2, the researchers take questions from the media.

Reporter 1: Do you think the idea of inflation really coming in our lifetime, be so well confirmed that it will fulfill the demands of the noble quality of physics and in that case which probe is most likely to give those results?

Krauss: I think the amazing thing about inflation is [that] it is completely consistent with what we see, and the key question, [you're right,] is: Will consistency ultimately be enough to convince everyone that it is absolutely true? I think many people think—and Scott can expand on this [as can John], [is that] what's been called a smoking gun, inflation of gravitational waves; it's a prediction of inflation that is ubiquitous, almost no matter what you can do. Well, in fact it is a generic feature of inflation, more generic than many other things, in fact, I've argued for 20 years it's the most generic feature that we should look for. So, if these waves are discovered—and both Scott and I have been part of a group that has been looking at we might be able to do in the next set of satellites that may look for this, and John has been a leader in thinking about building experiments to look for these things—if we detect gravitational waves from inflation, there is a real possibility of pinning things down [enough] so that one could perhaps convince every physicist that inflation happened. There are major stumbling blocks there, and inflation, at the same, time is unfortunately so robust that it could be consistent with almost any observation we can make, and that is a problem. But if we detect gravitational waves, I think we will be much closer to Alan having a free trip.

Reporter 1: And which probe is that?

Krauss: What's that?

Reporter 1: Which probe is now trying to answer that question?

Krauss: You could want to answer that.

Carlstrom: Looking for the signature of these inflationary gravitational waves, and the gravitational waves laid out from inflation at the time period; their imprint on the polarization of the cosmic microwave background.

Dodelson: So there a number of different experiments including John's that are sensitive to this. So for example, in Europe, Planck is going to be launched in April, so that will be much more sensitive [by a factor of 10] than the U.S. based WMAP satellite, and there are about a dozen experiments now looking for this polarization signature. So that to some extent, tells you something. These are very complicated experiments with dozens or more of people on each experiment. So people are voting with their feet. They think this is the most pressing problem.

Carlstrom: I think we will know in 10 years' time, we'll know whether or not we can detect gravitational waves from the inflation, but that doesn't mean we will detect them.

Krauss: And, in fact, the unfortunate thing is that the absence of gravitational waves is also completely consistent with inflation, in the sense that there are two fundamentally different theoretical ideas, one of which suggests strongly gravitational waves should be big enough to be seen in the next generation experiment. Another one, based loosely on the idea of extra dimensions, suggests that the gravitational wave signature should be small. And this is really important, we'll definitely learn something profoundly useful, but of course if we don't see them, what we'll learn is we'll rule out one set of models, one set of models is still be viable, but we won't have confirmed it, and of course confirming is always better than ruling out, I suppose.

Reporter 2: Can I ask you, for the help of some of us, what small is when you come to [a] gravitational wave?

Krauss: Oh! That's important. We don't mean small in terms of wavelength. These gravitational waves we will to detect will almost be the size of visible universe, but we mean, they'll produce signatures, temperature—well, in this case, the polarization of the microwave background—signatures which are at the level, well, the next generation, the best we can imagine doing is getting a 1 [percent] admixture of a signal from gravitational waves compared to the signal of the temperature fluctuations that we, kind of, measure in the universe. And 1 [percent] would be a, sort of, holy grail in a way because it is probably as well as we can do experimentally; and Scott may want to talk more about that, but it also distinguishes the kind of scale, if its bigger than 1 [percent] one set of inflationary theories are probably right. If it is smaller than 1 [percent], another might be right, but then just to add and as I often try and do, I muddy the water, we've also argued recently that, unfortunately, there are other mechanisms in the early universe that could also produce a gravitational wave signal that would mimic that due to inflation. And that's wonderfully exciting because it means if you discover these things, you have a great probe of the early universe, but it might not be, it just might not be a unique probe of inflation.

Steve: What's your time span for the return to the 19th century view because of what data is available?

Krauss: Oh, it's really soon, it's within about between a 100 billion and a trillion years; actually which may seem like a long time to you, [maybe not long] when you compare it to this press conference, but the interesting thing is that the universe will look large, I mean, the local universe will look largely the same at that point. The longest lived stars are much longer lived than that, so there will be stars like our sun, and there'll be planets around those stars and civilizations could be powered by solar power, so it's perfectly reasonable to expect that there'll be civilizations not that different than [our own] that could arise, but they'll live in an empty dark universe. And, in fact, what we said somewhat [facetiously] when we pointed this out was, we live in a very interesting time, namely, the only time at which we can empirically verify that we live in a very interesting time.

Dodelson: Can I just add one thing please?

Krauss: Sure please.

Dodelson: Again referring to this dark energy today, there are two possibilities that lead to optimistic branches and one is that dark energy today may not be vacuum energy, it may be something completely different; and a good piece of evidence for that is that inflation itself require[s] dark energy, so it kind of make sense to think, ["Well, we had some early [epoch] of dark energy which is something [we're trying to] figure out, maybe [today] there is also [a] new type of dark energy we are trying to figure out and it is not vacuum energy, so that would lead to a less pessimistic future. The other potentially exciting thing about dark energy is that it might be connected to very small particles called neutrinos. The mass scale is roughly about the same thing, so there are theories in which dark energy is connected to neutrinos. And if that's true, there's an enormous amount of research going on in neutrino physics today. The idea of connecting that primitive dark energy to something in the current, you know, pantheon of particle physics is tremendously exciting and [that] would [open up whole new] vistas in our understanding.

Carlstrom: And get very much.

Dodelson: Yeah, that's a good point.

Krauss: And let me add to what's Scott said that if, let me just add one sentence. [He's] absolutely right, of course, and we may be lucky, and I hope we are lucky; what Alan said is, I want to emphasize something about the negative features of what Alan said, [which] is that if the vacuum energy is dark energy, we won't be able to prove it is dark energy. Our experiments will narrow the uncertainty down to these parameters of dark energy, but the closer [it] gets to looking like vacuum energy, the less [we'll] be able to distinguish between vacuum energy and something that just looks like vacuum energy. And then unfortunately the only way to answer that question is theory, and theory may be guided by things like Large Hadron Collider, and that's why it's really an exciting fact that cosmology and particle physics are working together. But we may be unlucky and, as you know, for example, in particle physics, we have this amazing standard model which has survived the test of, unfortunately, of all experiments, over the last 30 years without really telling us yet what the fundamental physics is and we are hoping that the Large Hadron Collider will tell us the answer to that. But cosmology could be in a similar situation where these fundamental parameters are pinned down, but we need some new theoretical ideas. We don't know, and the great thing is not knowing because then you do the experiments and see.

Reporter 2: I want to follow [up] on what Scott has said, when you said connected to neutrinos what that mean? You're just getting connected to neutrinos.

Dodelson: That particles in fields responsible for dark energy are also responsible for the mass of the neutrinos. The problem is that I think part of the pessimism—and there was obvious some lingering pessimism in the field—is that we are inventing stuff, we are making stuff up; we [observe] this acceleration, and we say, "Okay, this is dark energy." I mean, you can play tennis without a net for only so long before people start to call you on it. So if we can connect this dark energy to something we know exists, like neutrinos—and by connect [I mean], for example, a field which gives mass to neutrinos is also somehow driving the dark energy—I think we'll all sleep a lot easier tonight.

Reporter 2: Will, this be an entirely new field, [or will it be an] existing field [manifesting itself in a new way]?

Carlstrom: Is it new physics?

Dodelson: It would definitely have to be. You know there are these charts describing the standard model of particle physics and Lawrence is right that we haven't yet had any experiments which lead us to move beyond that chart, [except in] the [area] of cosmology; so dark matter, dark energy, inflation, all require physics beyond the standard model. So this new field would have to [lie] outside that chart; so [it] will definitely be new physics.

Krauss: New physics and that might be probable in particle accelerators, and I think that's a key thing, because you then you have a new handle, and that's really what we need.

Steve: Right, another question.

Reporter 3: Are you ever afraid that dark energy might be a modern phlogiston theory?

Krauss: I hope it is. I mean, I think the one of biggest misconceptions about science is that we want to be right. In some sense we want to be wrong, because that [means there's something ...].

Reporter 3: Because it will lead you to the right answer.

Yeah, what was most interesting is that many of the basic ideas we now have are wrong, because that means there's a lot of work left for theorists, and so I think the point is that we don't have a theory of dark energy. That's a key, that's probably the key thing to stress. It is the most mysterious discovery from a fundamental theoretical perspective that has happened in a long time, and we have vague ideas; and the vacuum energy is of course good explanation except when we try and explain it, we get the answer wrong. It's the worst prediction in all of physics. And so it's very exciting from a theoretical perspective because it really means that there's something profoundly important we need to understand that we don't. And we are flailing about, and unfortunately Alan is right, that right now the best framed answer— which I wouldn't argue is that well framed—but that is the best framed answer is that, we have many universes and it is what it is because it is what it is, but boy, wouldn't that be an awful explanation?

Carlstrom: You [can all just go home] now, we're done.

Reporter 4: Are there any bigger machines, or more powerful machines with greater luminosity in the works that you know of that if the LHC doesn't find [it]?

Krauss: Well the physics community has been thinking, these machines take decades, at least a decade or two to design and build, if you have the political will and the economic will. And so what that the physics community has done is come together around, the particle physics community, around a machine beyond the LHC called the ILC, the International Linear Collider; it has got a good name; and research on that was being funded because we need to be able to develop these techniques well in advance. But, you know, at the current time, I would say, it is possible that in the lifetime of the people in this room, the LHC may be the last big accelerator, unless we have the will, the economic and political will and the international collaboration to put [it] together and that would be a real shame, I would argue. These machines sound expensive; they used to sound expensive before the bailout package. [It] used to be real money. But these machines are expensive. They might [cost] $10 billion but it is $10 billion spread over a decade; and I would certainly argue that if we as a civilization don't have that kind of money to put together to ask [and] answer fundamental questions then it's truly a sad reflection on our civilization.

Reporter 2: Can I ask, Alan, what the latest thinking is on whether there is any possibility of detecting these other universes; do they [intersect] our universe in any way that could be measurable or are they purely theoretically?

Guth: I think [that's still up for grabs]. People are certainly doing research on the question of what it would look like if we collided with another bubble and how likely it is. It is certainly in principle possible for bubble universes to collide with each other. There is no doubt about that. My own guess is that when the dust settles, it is going to be something that's so unbelievably rare that we can't really expect to detect other universes in that way, that's my guess; but it is certainly well worth exploring and work is being done, and I could be wrong there; what I'm, expressing is only a hunch.

Krauss: But that doesn't mean it will be metaphysics. I want to point that out. I want to show my optimism. People said, "If there are other universes, and you can't detect them, then what's the difference between that and metaphysics? And the answer is we might be lucky enough to come up with a theory that actually explains what we see; explains why the proton is 2,000 times heavier than the electron; explains why there is three generations of elementary particles; explains how the forces could be unified; and therefore is testable on a whole realm of ways, but one of its ancillary predictions may be that it definitely produces inflation which would produce these other universes. And then you would say, well if I measured 95 predictions of this theory, and it explains everything and [it] explains one thing we can't see, then we'[re willing to] accept that one thing we can't see. And the same has been true in physics. Many times there are theories that have explained what we can see but make predictions that we cannot see, from the existence of atoms onward. And so it may come down to the point where at least we have strong scientific ways of probing a theory that does predict extra universes.

Reporter 5: [One of the things that comes up in our newsroom a lot is that this stuff is so divorced from the everyday reality of people that don't wor in [your] field [When you're trying to explain it to people who don't work in your field,] what are some of the basic things you can tell them about how [their daily] life is connected to and important to [this]?

Krauss: Well I just came personally just came back from Paris a little while ago—this is the international year of astronomy in honor of Galileo's discovery—and I think if you look back with a historical perspective and ask how astronomy has changed our cultural perspective and understanding of ourselves, it is profound. Right? It was Galileo's discovery of the moons of Jupiter that told us that we are not at the center of the universe, to [the] discovery of the big bang [that us] told that universe had a beginning. And so I think while these questions are cosmic in a real sense and [a] metaphorical sense, then the fact is that our perception of where we came from, the fundamental questions that everyone ask[s] about themselves is inevitably determined by these discoveries. And absolutely right, there is no practical significance to them, except to understand our perspective of our place in the universe; but I would argue the same is true for art, literature and music. And we never ask why we do that. And so the only reason to ask these questions is because we want to understand ourselves at some level, and cosmology gives us a profound, [can profoundly] affect of our view of ourselves. It is true that whenever you ask fundamental questions from an experimental perspective, that the techniques you develop will inevitably produce economic benefits and that has happened; from the worldwide web to other things, but I think, my own feeling is you should never justify asking fundamental questions because of the ancillary benefits. It will affect our economy. It may produce the thing that will change our economy a generation [from] now more than anything else, but the questions themselves are worth asking.

Reporter 6: If I understood correctly it is the dark energy that would make the universe less falsifiable in the future?

Krauss: Yeah, well it would, yes it would change the picture of the future more than anything else, and yes, the dark energy is the culprit that has changed our thinking in almost every way.

Reporter 6: What's the mechanism?

Krauss: Oh, that mechanism is quite simple. The dark energy is gravitational repulsive and it causes the expansion of the universe to accelerate, and distant objects will speed up and eventually be moving away from us faster than the speed of light now that sounds like it is not allowed by Einstein, but we lie. You have to be more like a lawyer and parse it more carefully: Nothing can move through space faster than the speed of light, but space can do whatever the hell it wants as far as we know and space can certainly expand faster than the speed of light. And even if you don't have dark energy, there are regions of the universe that are moving away from us now faster than the speed of light and what happens when that's the case is they carry objects with them like a surfer on a wave and the light from those objects cannot reach [us] so eventually the universe will disappear [from] before our eyes in that sense.

Reporter 2: Can I ask a question that had been worrying me? If the universe inflated itself out of [borrowed] energy and then continues to expand indefinitely, [ever] faster and faster we end up with what sounds to an economist like a contradiction, that we have a war which will never be foreclosed.

Krauss: Well, Alan put it well. I'll let him say [it], it's the ultimate free lunch; you want to do it?

Guth: Yeah, my slogan is the ultimate free lunch, it is [in fact not a] mortgage, that's the point. Even if inflation is not right, the universe itself given what we observed about it is at least very close, if not exactly at the point where the total energy is zero, where all the energy of the galaxies and stars and all those things—which of course is positive energy—is counter-balanced by a negative contribution to the energy. Energies are not always positive. The negative contribution comes from the gravitational fields that fills the universe, and as long the universes near this borderline between being open and closed, the total energy is very near or exactly zero.

Reporter 4: And I am struggling with the concept of something to [being] near zero. It seems there is a huge difference between zero and ...

Guth: Near zero. Well, there probably is, that's right. All I am saying is observationally we can tell near zero. Theoretically I think it is very appealing that [it]'s exactly zero.

Krauss: And that's one of the things that's wonderful about inflation. It predicts a natural mechanism for the energy to be essentially exactly zero, and Alan's observation of [a] free lunch I would argue is extremely profound because it really means that, I have written about this elsewhere, but that the universe could start from nothing. People say, you know, how can you get nothing from something, that used to be the biggest argument for God for some people. And the answer is it's perfectly easy that you can start with nothing because [if] the total energy of the universe is zero now, it was zero back then and quantum fluctuations and other things could easily create it. So I would argue that science has a mechanism that's perfectly rational and natural for creating a universe from nothing; in fact Alan's mechanism in some sense is the most natural. And that to me goes a long way to answering this puzzle of how could you get something from nothing.

Reporter 7: What's the probability that some of the assumptions or even hypothesis I suspect that are leading us to dead end roads?

Krauss: The probability is that most ideas in physics are wrong; if they weren't anyone could do it. I mean, the probability is that, you know, much of what we are saying about our theoretical speculations will have to be revised, of course. That's generally the case and...

Dodelson: I think [what you said before] is true; people want to be wrong about all this stuff. The problem is there are dark matter, dark energy, inflation, and there are so many sets of different observations pointing to the same new stuff, so it's very difficult, I mean, people try to come up with alternative models, but there is always observations which constrain them. So, you know, it's possible we are on the wrong track, that we will have to completely rethink everything, but there are so many different sets of our observations, it's very hard to see how we will be able to wriggle out of any of these things.

Krauss: Yes, and what is certainly true is that all of the observations in cosmology from the fundamental CMB measurements to the measurements of large-scale structure to the measurements of dark, the amount of mass in the universe, all seem to be converging on a single picture. The problem is that all aspects of that picture cannot yet be understood on fundamental grounds; but I will say that one of the great virtues of inflation is that it has explained many of the features and it allows an explanation of that many of the features of that picture for which otherwise right now there is no other explanation.

Reporter 3: (unclear 22:04) if we take the dark matter particles or use supersymmetric particles, for example, neutrilinos and axions, [to] help to solve the problem also of dark energy.

Krauss: Well, no and yes, I mean, [we] used to think the biggest problem was dark matter; dark matter is profoundly important to measure this stuff and the fact that we might see at the LHC is or indirectly with looking at annihilation of dark matter particles in the galaxy is profoundly important. What it will do, if we discover these dark matter particles, it will tell us [that] a number of key theoretical ideas in particle physics are on the right track. For example, supersymmetry—if we discover supersymmetric particles, it'll tell us something, I mean, that's a profoundly important idea that will affect the direction of theory; and supersymmetry, it is true is at the basis of a lot of ideas including string theory. It is not a true statement—and I want to emphasize this—that if we measure supersymmetry in anyway, we have evidence of string theory, but it'll direct our theoretical ideas in ways that maybe important for ultimately answering that question.

Dodelson: I guess another possibility is that if we detect at the LHC evidence for extra dimensions.

Krauss: Yeah.

Dodelson: Then that would also point to a different framework for understanding dark energy potential.

Krauss: Absolutely, that's not likely but absolutely. I mean, so that's why you have to keep looking. You don't know where the answer is going to come from and you got to keep looking, and in a healthy world, you look in all the directions that are possible.

Guth: Let me add one other thing that could be seen at the LHC, which I think would make most of us unhappy if it's seen, but we could see evidence for more fine tuning in nature than we've already seen in the cosmological constant; and that would be taken as evidence for this multiverse, anthropic picture where the laws of physics are not determined by fundamental principles but rather by a wide variety of things happening and certain things selecting for life.

Krauss: And what we may see at the LHC—this should be very sad—but we may see nothing, right? We may see nothing. Yeah, but I think, the thing I want to stress that the journalists should stress is that seeing nothing is sometimes important. I mean and I worry that, for example, if we see nothing at the Large Hadron Collider then that would be an argument for people to say, "Oh! we shouldn't build the next one because after all these guys are just saying they're going to keep finding things," but seeing nothing would be profoundly important. It's happened before, from the Michelson-Morley experiment, [in] which seeing nothing led to some [sense] provided the basis of special relativity; and so it will give us, no matter what happens, it's going to profoundly affect our picture of fundamental physics in a way which is of vital importance.

Reporter 8: [Can you categorize what] you mean by, if the LHC finds nothing—what does if "it finds nothing" mean?

Krauss: Well, I mean, [it] finds nothing new. It's looking for example, I mean, everyone knows that one of the things it's designed to do is look for this particle called the Higgs particle, which is a vital part of the standard model. And all of the indirect argument[s] suggest, which is a reason why it's been built and that's another important thing; we are not just building it there because we have the money, it's because, or we don't have the money, because all that physics tells us it's quite likely to find something there. But what's just been realized, of course, is by thinking about these fine-tunings that may be possible in nature that Alan was referring to, is that it's possible to fine tune the universe so that the Higgs is not observable. And if that were the case, Alan is absolutely right; the only really sensible explanation is since all of the evidence suggest that unless you really fine tune things, the Higgs should be observable at the LHC or a machine like it, then it would tell us that there are some other fundamental fine tuning in nature that would strongly suggest that the universe we see is not generic and is very special. And that would certainly provide evidence that we're an outlier and therefore there must be more universes.

Guth: Let me say that, well what Lawrence said is probably true, I'm not absolutely sure. What is also true is that we find the Higgs and nothing else...

Krauss: Yes, that's another possibility.

Guth: Most of us would call that finding nothing. We're pretty damn sure that the Higgs is there and finding the Higgs and nothing else in terms of physics will have similar consequences [to] what Lawrence was talking about.

Krauss: Yeah.

Guth: That is it will require so much fine tuning, these ideas like supersymmetry are promoted in that they explain why the Higgs is so light. If you find the Higgs and no supersymmetry and nothing like supersymmetry, [that] provides an alternative explanation for why the Higgs is so light, then the lightness of the Higgs particle becomes a problem like the cosmological constant. It's just far away from what we expect. And a plausible explanation, and the only one that would be left under this hypothesis, would be that there are many universes and life only forms when the Higgs field is light.

Carlstrom: My own hope is that what we see at the Large Hadron Collider will be none of the above, and the world is more exciting than we thought.

Reporter 9: If you see something, if you find a Higgs particle, it's good. If you don't find the Higgs particle, it's good. Is there anything you can see at LHC or at some wildly dreamed-up particle collider, that would say there is something, definitively, that this is the right idea or this is a wrong idea, you know, inflation is here or not.

Krauss: Wow! That is going to be inflation. I mean, look we're reaching out to look [at], to think about the universe in scales that are so far much different than we can now measure, that you have to understand, it's the biggest extrapolation in probably a history of physics.

Carlstrom: The energy scale, which we think inflation may have happened [on]out is way beyond what could be reached by the LHC or [the ILC or] any collider [we] could possibly [build] on Earth.

Krauss: So we have to take baby steps, and there is always a chance of getting lucky, but what we need is some empirical tests of ideas that are leading us in the direction. And so the discovery of supersymmetry for example, if it's discovered, it will definitely direct our understanding of fundamental physics and suggests ideas about the scale at which inflation may have happened, which will restrict things tremendously. So we will get new handles, but that's the interesting thing. The experiments and observation, cosmology has been so successful that we are seriously trying to address questions on scales that have been—or just as I said, at the very beginning—were previously unimaginable, and therefore it may take quite a while before we can get the definitive experimental answers, and we have to recognize that possibility.

Carlstrom: I think the way to falsify inflation is to come up, keep finding observations, finding things and then a new theory which would replace inflation and makes predictions which we could test, is probably the only way inflation is going to go away.

Krauss: Yeah, I mean, there is...

Carlstrom: In that I can't think who knows what we'll find in the next 10-20-30 years.

Krauss: There's one thing would you agree? I mean, there is a possibility of the fluctuations that are seen in the microwave background [are] what are called, very close to what are called, Gaussian and that means, kind of, as random as they can be in a sense; and if when you probe much deeper, you found that there were some fundamental Gaussian—and it of course again would rule out inflation because it can accommodate things—but it would be something that would directly point us in a sort of a different direction, do you agree?

Guth: Well it would point us towards certain types of inflationary models.

Krauss: That's probably even then it can falsify. And I mean by these things, by falsifiability. We may just have to give it up as a fundamental principle at some level and that doesn't mean science will end at fundamental scale, it means the type of questions we can ask [will] be constrained.

Steve: That was Alan Guth, John Carlstrom, Scott Dodelson and Lawrence Krauss. You can read Krauss' article in the March 2008 Scientific American on our Web site, it's called "The End of Cosmology?"

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: Conan O'Brien recently reviewed the four forms of Boron on Late Night complete with diagrams.

Story number 2: Green tea has been found to augment the effectiveness of treatment for a couple of kinds of cancer.

Story number 3: The skeleton of a mammoth was found in Los Angeles.

And story number 4: Another fossil of an ancient whale indicates that the whale probably gave birth on land.

Time's up.

Story number 1 is true. Conan did do a feature about the four forms of Boron after The New York Times had said there were only three forms. You can see O'Brien's hilarious rant, just Google "Conan and Boron".

Story number 4 is true. A very rare fossil find of a pregnant whale indicates that the whale probably gave birth on land because the fetus was positioned to be born headfirst. For more, check out the February 16th episode of the daily SciAm podcast 60-Second Science.

And story 3 is true. An almost complete mammoth skeleton was unearthed in downtown Los Angeles at a construction site near the La Brea Tar Pits. The mammoth died about 40,000 years ago. He was in his late 40s. So young! Tusk, Tusk!

All of which means that story number 2 about green tea improving therapy against a couple of cancers is TOTALL....... Y BOGUS. Because what is true is that a compound in green tea was shown to actually interfere with treatment against multiple myeloma and mantle cell lymphoma. The researchers had assumed that the tea compound would enhance the activity of the drug Velcade, but it apparently bonded to the therapeutic molecule keeping it from binding to its true target. So remember everything you swallow regardless of how natural it is, it is still a chemical which may interact with other chemicals.

Well that's it for this edition for Scientific American's Science Talk. Check out http://www.SciAm.com for the latest science news including our coverage of the meeting of the American Association for the Advancement of Science. For Scientific American's Science Talk, I'm Steve Mirsky. Thanks for clicking on us.

Science Talk is a weekly podcast, subscribe here: RSS | iTunes

In part 2 of this podcast, cosmologists Alan Guth from M.I.T., Arizona State University's Lawrence Krauss, John Carlstrom from the University of Chicago, and Fermilab's Scott Dodelson take reporters' questions at the annual meeting of the American Association for the Advancement of Science in Chicago on February 16th.