She has conducted research on the psychology of meditation for over 25 years, including investigations on the effects of meditation on heart rate control, general well-being, spirituality, psoriasis and anxiety disorders. Her other (but related) line of research is investigating the role of spirituality in adjustment to serious medical illness. A recently published randomized intervention study documented benefits of a very brief physician-delivered spirituality intervention offered to cancer patients on quality of life, emotional well-being, and satisfaction with care. Current work is investigating how religious and spiritual resources, from the patient’s perspective, may help in adjusting to cancer. Matter&Beyond spoke with her on her research.

Matter&Beyond: Dr. Kristeller, you are doing research on the spirituality of cancer patients. You also developed an intervention technique called OASIS that could benefit the patients who are going through spiritual struggles. What was your starting point for this project?

The OASIS Project stands for Oncology Assisted Spirituality and Intervention Study. In this project, we were exploring how individuals draw on their spiritual and religious resources to deal with having a cancer diagnosis. The other question was how physicians perceived that aspect of their patients’ resources and whether they felt it was appropriate to bring it up in the medical environment. First we went out and actually asked physicians what they thought about the role of patients’ spirituality in dealing with cancer. We actually got back a very positive response. Substantial proportion of the physicians actually felt that it was helpful to their patients; it was something that was valuable to engage within the medical environment.

M&B: Were they able to address the spiritual dimensions of the patients?

What we found out was that they didn’t know how to do that. They were afraid if they brought it up, their patients might get upset with them and they’d be triggering off a reaction perhaps that would require so much time and effort on their part to explore with their patients that it just wasn’t practical. So when we found that out from the physicians we decided that we would systematically look at that from that patient’s side.

What we heard from patients was that they also wished to bring it up in the medical environment but they felt that the physicians wouldn’t want to and that they would bring it up if the physicians asked about it first, and the physicians were saying they’d talk about it if the patients brought it up first. So nobody was bringing it up.

So we moved this onto the next step. What if we taught the physicians a particular approach to bringing up this issue with their patients because we couldn’t sit down and teach the patients how to do it. We decided to take a risk and teach physicians how to bring this up to their patients in a very simple way. And we found a few very brave oncologists who were willing to work with us around this and we designed literally a 5-minute patient centered way of introducing this concept.

M&B: How did you design this approach and what were its characteristics?

In a way, we’re guided by previous research on how physicians can talk to their patients about difficult topics. This is actually research that I had done previously in relation to other difficult topics like smoking and alcohol use. And what we did in those cases was we taught the physician a very neutral, gentle supportive way to introduce those issues with their patients and then we took a look at how we could use that with introducing the questions about spiritual resources. So a physician may say something like “Many patients draw on their spiritual or religious resources to deal with something like finding out they have cancer. As your physician I would like to hear more about whether that is true for you, it may or may not be, how do you feel about that?” And that very gentle open way of introducing it feels very comfortable to the physicians and it feels very comfortable to patients. And what we find again is most of the patients respond very positively to that.

M&B: What if the answer is no and they are not interested in talking about spirituality?

We also taught physicians that if the response they get back from a patient is something like “oh no, I’m not religious or I don’t want to talk about that,” how they should respond to that. They should say something like “really what I’m concerned about is how you’re dealing with this and I’d like to hear more about that. Is that ok?” And that shifts it just a little bit. But for about 90% of the patients, they really open up and they are responsive and they start to talk about it and if they are a little hesitant we then teach the physicians how to draw them out a little bit more. Very simply saying, “Tell me more about that. I’d like to hear more about that. Are there any problems you’re having around that? Who else can you talk to about this?” It’s very important. So being encouraging and thanking them for having the courage to share their feelings with the physician. Asking them a little bit more about how they draw on a sense of inner meaning and peace, because we’ve identified that in research as one of the key elements for moving to a different level of coping with cancer.

To our surprise this actually worked very, very well. What we found was that patients have appreciated it. Over 50% of them actually told us after the fact that they had found that conversation helpful to them in dealing better. And about a month after this very brief exploration, they actually said that they were feeling less depressed and they were coping better in comparison to patients from the very same physicians who didn’t get this, who just go their usual appointment. So we’ve been continuing to work on this line of research to deepen it and to expand it at this point.

M&B: You also discuss that a small number of patients are coping in a negative way with spirituality. How does it happen?

Our research and research from some other groups, for example Harold Koenig’s work at Duke, is systematically coming up with a pattern that shows that individuals who feel angry at God, who feel that they’re being punished by having cancer are not doing very well.

Most people feel that at some point. But what I’m talking about is a sort of enduring ongoing struggle around this. And what we find is individuals who are really caught in that struggle in fact are doing very poorly. They are more depressed, and their relationships are not going as well. We don’t have any evidence at this point to show that it actually affects the course of their disease. That would be a challenging kind of study to take on and we haven’t been able to do that. But certainly it’s affecting their inner struggle and their inner well-being. What we encourage physicians to do if they realize that one of their patients is struggling at that level is to encourage the individual to find somebody else to talk to, maybe a Chaplain for example from the medical environment. We really encourage them to look to that and to try to provide those resources and not take that on themselves.

M&B: Maybe it is difficult to estimate how the constant spiritual struggles affect recovery time, but maybe it is easier to estimate how it affects the quality of life.

The individuals caught up in that struggle have a poorer quality of life in general and the research again is pretty consistent in that. And of course it would be naïve to say that you just turn that off. If somebody is struggling in these deep personal issues, they deserve to be recognized and I think we have to assist the individual to find some way to talk to people in their own personal circle of friends, family, religious community about how to deal with them.

M&B: Regarding spiritual intervention, what is the general opinion of the medical community? Is there a growing interest?

I think we are just shedding some light on this. Given how positively the patients respond to even just 5 minutes, I think that there is a growing awareness that there can be a role for this. Within the care of the whole patient, when you shift into the perspective that the spiritual and religious resources people bring to a medical crisis are actually tremendously valuable, and the more they can bring those to the crisis the better they’re going to be doing then. I feel that that defines within the medical environment in a different way.

One of the issues that often physicians would bring up with us is “I don’t know if I have the same beliefs as my patient does” and “if I don’t have the same beliefs maybe it’s not appropriate to bring this up.” And one of the things we do in our training is to work with them around that. Saying you know it isn’t about the beliefs that you have and whether they match your patients. It’s about listening to your patient; it’s about hearing the underlying feelings and meaning that the patient has.

M&B: In terms of spiritual response to cancer, do you see people going through a spiritual transformation?

Let me give you a little bit of frame on that. We’re funded on the Spiritual Transformation Project. When you think of spiritual transformation you’re actually thinking about a real shift in people’s beliefs and people’s sense of themselves as a religious or spiritual person, their relationship to God, or their sense of relationship to God. We’ve compared our data to data that’s been collected on AIDS patients in Miami. Something like half of the AIDS patients communicated that spiritual transformation happened to them. We had 2 out of 100 cancer patients relate that level of change occurred.

M&B: Fifty percent compared to two percent. That is a huge difference. What is your explanation for that?

A couple of reasons I think, one is that even though cancer is a very frightening disease, it’s nowhere near as frightening as AIDS. The prognosis is much better in truth. The other is that the AIDS patients were really people who were struggling with their lives in general. Most of our cancer patients have really quite well-functioning lives. They’re already members of religious community. They don’t need a transformation. They just need to deepen or engage that religious support more fully or the spiritual side of themselves. So, one of the issues is that transformation isn’t necessary, it isn’t needed for this. Engagement though is what we’re talking about.

M&B: What are the fundamental difficulties in doing research on spirituality?

One of the things that is so challenging about this area is trying to measure, trying to capture very elusive concepts and do it in a way where we can systematically identify them, where we can frankly put some numbers to them. So we can compare individuals, so we can look at the effect, for example, of a stressful life event on something like spirituality. So, one of the other lines of work we’ve been doing here is to develop the framework for measuring what we call religious and spiritual engagement, and it’s very challenging to do that. Within Psychology, there’s a long tradition of trying to capture these psychological processes, something like depression or fear. And we have lots of different measuring tools.

M&B: Is there a widely accepted measure of spirituality and religious participation among the healthcare and medical research community?

When we started working in this area, what we discovered were a couple of hundred different scales to measure what people called religious and spiritual involvement. But most of them had been developed in very small groups of individuals, they hadn’t been put into a larger theoretical model and we knew there were probably not hundreds of different dimensions but we didn’t know whether there were 2 or 4 or 5 or 10 and one of the projects we’ve done here is to identify using a group of these measures that seem to capture different aspects of spiritual and religious involvement like belief, compassion, like sense of growing within oneself. As in mystical experiences, we’ve had several of these projects where we’ve given this set of measures actually over almost a couple of thousand people at this point.

Another dimension is interestingly their willingness to tolerate questions about their beliefs and their spiritual well being. Tolerating those questions seems to be a separate and important element that is linked into doing better, to growing more. Mystical experience is a separate dimension so someone who has a mystical experience may or may not be strong in their belief system. Having that may shift that strength but it’s somewhat separate.

We focused on several dimensions. One of the 5 or 6 dimensions is what we call spiritual struggle and that is a separate dimension and again people might be high or low on their strength of their beliefs. If that dimension is strong or high, you do see a lot of distress not only in that part of the person’s life but often in other areas of their life.

M&B: People often think that hope, love, and compassion are the indicators of spirituality. But you are giving other dimensions as toleration to questions or having a mystical experience etc. Do you choose them because they are easier to analyze?

That’s a very good question. It’s very important to include as a part of someone’s total spiritual well being their ability to feel compassion towards others; their ability to feel hope. One of the challenges now in this area is to understand those dimensions in and of themselves and I see them more as overlapping with spirituality rather than defining it. And I say that partly because there are many people who feel that they are not religious or spiritual perhaps, but they certainly have the ability to feel hope and they have the ability to be compassionate toward other people in their lives. From the perspective of Psychology, we don’t have the answers to this yet but we’re applying tools out of Psychology that we’ve used in other areas of understanding human emotions, personality, and patterns to try to apply them within this arena of understanding something as complex as religion and spirituality.

M&B: You are using tools from both religion and psychology. Are psychologists generally interested in spiritual experiences?

Well. William James who is considered one of the founders of Contemporary Psychology in the 1800s wrote the Varieties of Religious Experience. And he wrote that from a very sophisticated perspective where he said we really do need to look at some of the universal aspects of religious or spiritual experience. At the time he didn’t really have the tools to do that but he introduced the discourse around the value of doing that, the value of understanding those very human experiences from a psychological perspective. And it began with a respect for those experiences rather than discounting them. And I think that that is a very important distinction.

In contrast, when some of the thinking that came out of the Psychoanalytic Schools and particularly Freudian theory tended to pathologize those experiences considering them as an anomaly or like a sickness. In fact one of the differences between Freudian thinking and Jungian thinking was the discounting of those experiences as regressive and pathological. It is an aspect of human experience that could tremendously contribute to the best in human nature. And if understood and cultivated in appropriate ways, this could tremendously increase people’s ability to engage with their fellow human beings to act ethically.

Matter&Beyond: What was your motivation for writing the book, The Heart-Mind Connection?

Well, that book was a collaboration with Dr. Ting who is a Cardiovascular Surgeon and it was actually his idea. He’s a very enlightened surgeon in that he, over the years of training in a practice as a cardiac surgeon, came to realize that the experience of undergoing cardiac surgery certainly taxed the mind and that the interaction of mind and heart was extremely important for outcomes. If you’re a cardiac surgeon and your goal is to improve your patients’ lives it became very clear to Dr. Ting that in order for that to happen cardiac surgeons and cardiologists had to be mindful of the fact that patients needed to be emotionally and cognitively intact, and so he asked me to collaborate on this book, and the book focused on the interaction between mood states and cardiac states.

M&B: What is the nature of this interaction? Does the heart affect the mind or does the mind affect the heart?

It’s bidirectional. There is an interaction or there is a relationship between mood disorders such as depression, anxiety, anger, and hostility and the actual human heart. The connection between those mood disorders and cardiac function is extremely important. But then also if you go into the experience of having heart disease and you were fortunate enough not to have one of those mood disorders, the experience of having cardiac disease will put you at risk for developing mood disorders. So it’s bidirectional. You can start out with heart disease and wind up having your health complicated by mood problems, or you can start out with mood problems and have your health complicated by heart disease. There’s an unholy alliance between depression and anxiety on the one hand and heart disease on the other.

M&B: What happens, let’s say, if you are someone who has a history of a major depressive disorder? What happens to his or her heart?

Major depressive disorder is a condition characterized by certain clear-cut symptoms, and those symptoms include having a depressed mood everyday most of the day for two weeks or more that includes losing pleasure in life, something we call anhedonia, not being able to take pleasure in normal activities that would normally make you happy. Along with that is loss of interest in things, guilt, or feelings of hopelessness, helplessness and worthlessness, loss of energy, loss of concentration, loss of appetite, sometimes even leading to weight loss, not being able to move the way you’re used to. So it’s sometimes you just curl up in bed and this is something we call psychomotor retardation or withdrawal. On the other hand sometimes depression makes you agitated so you can’t sit still and you’re running around sort of ringing your hands and so on. And then the final symptom of major depression is suicidality or morbid thinking. Always focused on death or wanting to die. So that’s the common sort of a cluster of symptoms we see in major depression. Now, say you have no history of heart disease but you suffer from major depressive disorder. You increase your risk of developing heart disease by having this condition of depression. So your risk of having a heart attack for example goes up like 1-1/2 to 2 times what it would be in someone without depression.

M&B: Is it similar with anger and hostility?

Some people believe that if you’re an angry person or a hostile person, that also increases your risk of developing depression. Say you have depression and you unfortunately have a heart attack. If you remain depressed then your risk of having another cardiac event, another minor cardiac infarction or a cardiac arrhythmia would go up three and a half times what it would be if you weren’t depressed. So that means that this connection between the brain and the heart, between depression and cardiac disease are tremendously important in terms of public health. Because those two diseases are causing most of the disability that exists, by the year 2020, the World Health Organization predicts that heart disease will be number one and depression will be number two in the entire world. That includes the developed world, the industrialized countries as well as the developing low income countries around the world. So in terms of the book that we did we thought it was important because these two illnesses, first of all feed off each other and cause a lot of heartache in the population but they also are the most important diseases in public health.

M&B: The heartbeat change is associated with love or certain joy. What is the physiology behind that?

Let me preface it by saying that this is the age old philosophical question which Plato and Aristotle sort of debated. Love is an idea as Plato thought. So, is there sort of an idea of beauty and of love that exists outside of the materialistic world? Are we somehow plugging into that ideal world of love as material organisms? Or does it come as a result, as an epiphenomenon of the material world we’re living? Does it emerge from the biological material world that we’re living? That in a way becomes a philosophical question. As scientists when we see human behavior, there’s something that we do, and it’s called reverse engineering. Let’s look at the behavior or the experience of human love. Where does that come from? Let’s work backwards from human love to try to understand in a biological way where it came from. We are the ultimate mammalian life. We might start a little controversy about that and especially with the all wars that we fight, but be that as it may, we are these high level, high functioning mammals. Our infants are born [in need of] altruism, which means that they are absolutely helpless when they are born. So parenting for the human being is extraordinarily important for the continuity of our species, and so our infants are in total need of care.

M&B: Isn’t this the same for all the animals?

It’s different in reptiles. If you go to Borneo and you study the life of the Komodo dragon, you’ll find out that komodo pups know immediately what they have to do when they plop out of komodo mommy. They have to roll around in their own feces in order to throw mommy off the scent because mommy will look at them as food. So that’s their strategy for avoiding being eaten by mommy. They also know how to climb up trees to get away from mommy. So here the survival strategy of reptiles is not one of attachment; it’s one of separation. All psychiatry is tied up in that simple fact. There would be no psychiatry if we were reptiles. But because we’re mammals, there’s psychiatry because all of the disorders we have are really disorders of a dysfunction in parental and social attachment. Only mammals for example have a part of the brain called the paralimbic cortex. So reptiles have primitive limbic areas, they have hippocampus, they have amygdala, so they show fear, and they act when they’re threatened, etc. They’re outfitted with those structures which allow them to do those simple attachments-attachments to food and to sexual objects etc., but don’t allow them to do social attachments very well, and there’s some reptiles that are better at it than others. Crocodiles, for example. They do a version of taking care of their pups. Birds also take care of their nestlings very well, and crocodiles actually have brains that are more kind of on the bird-like end of the spectrum, allowing them to do a better job as reptiles taking care of their young and having something of a social life. Nothing to the extent that mammals do and you can look at a mammal brain, and you can see where this is taking place. So the anterior cingulate is an area of extreme importance for mammalian behavior.

M&B: This unique mammal feature, the limbic system and the paralimbic system; would you elaborate a little bit more on them?

I had the privilege of meeting back in 1990 Paul McClain, who is a famous neuroscientist who coined the term limbic system. He studied emotional parts of the brain in reptiles and in monkeys and in human beings. He talked about what he called the mammalian behavioral triad. There are three things that mammals do that reptiles don’t do very well. One is that all mammalian infants cry for their mothers in the same way, so every lamb baas for its mother the same way. Every human infant cries for its mother in the same way, that’s called a separation cry, and you can study it. So when you look at rats they have an ultrasonic isolation cry; you can study it, and you can deprive them of relationships and you’ll see the cry. That’s typically mammalian. Another feature is play, so mammals play, and that serves a social binding function. We play sports together; it serves a social binding function. Then the third thing is maternal nurturance which is extremely important, and mammals do that parental nurturance piece pretty well.

M&B: Are there any experiments that may illustrate the role of love?

There are a couple of experiments that Paul did and they are very illustrative. They get us back to a focus on love. So one experiment was to take hamsters and you can ablate, sort of take out the anterior cingulate. When you do, the hamster pup no longer cries for its mother when it’s separated and the hamster mother no longer responds when the hamster pup cries for her. You can also put morphine in that area, and get pretty much the same results. So you could put morphine in the hamster pup’s brain in the anterior cingulated, and the hamster pup will no longer cry for their mother, it distorts that bonding. And you can do that with squirrel monkeys too and you’ll get similar results.

M&B: Do the results apply to human beings as well? Could the use of morphine stop a healthy heart or brain from giving love or responding to love?

One of the real problems that we face in psychiatry is when we run across an addicted mother. What happens to the mother child relationship when the mother is addicted to heroin or to cocaine or to other drugs of abuse? The child gets neglected, the mother no longer responds to the needs of the child. So we see there’s even a reflection of those basic experiments in the human model when we’re talking about maternal-child relationships. So again that’s kind of circumstantial evidence where there’s reverse engineering, and mothers also have this phenomenal hormone, neuropeptide hormone, this again is exclusively mammalian, called oxytocin. So it’s used in pregnant women to get them ready to give birth, and so once a pregnant woman gives birth it’s responsible for milk production and so on. This is another example of this – if we think about maternal love, one of the requirements for maternal love is that there needs to be oxytocin involved. Oxytocin needs to allow that brain to have the experience of being connected and bonded to offspring.

M&B: The relation between the brain and the other organs such as the heart, is it really a top down relation where the brain commands, or is it a bottom-up relation where bodily sensors form the human brain?

What you’re referring to when you bring up this fact that the body sends markers up to the brain, and the brain takes note of that and becomes behaviorally engaged, that is absolutely true, and it’s something that Tony Damasio calls a somatic marker hypothesis of how the brain works. This is also something that William James postulated in the late 1800s-that emotion is a reflection of the body’s activity. Your heart racing or your stomach turning, emotion is secondary, it’s the brain trying to make sense of what the body is going through. What came first, the chicken or the egg, that kind of a problem. The fact is, the organism works as a unity and you need all of its component parts for it to work, and you really can’t tease a part, what came first and what came second.

M&B: From our physiology, it is evident that we are born to love.

It is very spiritual about this kind of understanding of love and connecting it back to the brain. How the heart becomes a reflection of what the brain is about, and also this need we have as human beings for connection. Spirituality really is this need we seem to have as human beings to be connected to something greater than ourselves. So we have this part of our brain, the prefrontal cortex, which allows us to think into the future and when we think into the future, we gain security when we see a future of connectivity, of attachment. That becomes a workable definition of spirituality. So many of us feel connected to a higher power, to God or to nature, but that is also a common reflection of what people refer to as love, and again you can choose to understand its biological origins. The body will be connected up with that whole experience, so your heart will be connected up. If you’re feeling connected to God, or to the scene of an ocean, and you’re feeling connected to the universe, when you’re looking up at the stars, there will be a bodily sensation connected up with that experience, and that will become for you part of what you understand to be spirituality.

Introduction

Human beings have wrestled with questions about the origin of our existence and the fabric of our universe for thousands of years. This questioning formed the discipline of cosmology. Dr. Natarajan explores the nature of our world and shares her perspectives about how new scientific discoveries are reshaping our understanding of the universe and our place in it. Until very recently, the universe had been considered a vast empty space. But the Dark matter theory states that the universe is not empty, but rather filled with an invisible matter. As new mysteries unfold, Dr. Natarajan points out that it is our fundamental human curiosity that leaves us no choice but to explore the universe and how we fit into its grand picture.

M&B: Dr. Natarajan, you work on dark matter in the universe. What is the theory?

It turns out that the bulk of the matter in the universe is not made of ordinary atoms that you and I or the universe that we know and experience is made of, but instead made of this mysterious particle. Ninety percent of all the matter in the universe is dark matter, and we believe this is a set of particles that was created very early in the universe. These particles do not have charge, but they have mass. Since they dominate the mass of the universe, it turns out that they really form the scaffolding in the universe around which all galaxies, stars, and so on, form. They are sort of the basis or the framework within which normal atoms actually cool to form star galaxies, and then have generated us.

M&B: What is the evidence for their existence?

The reason dark matter remains a mystery, – although there is incontrovertible evidence for the existence of dark matter – is the fact that you only detect it indirectly. What I mean by that is you detect its presence because it has mass, and since it doesn’t have any charge it doesn’t couple to any radiation. So you don’t see radiation in any wavelength in the electromagnetic spectrum: no X-rays, no gamma rays, no visible light, nothing. But since dark matter has mass, it aggregates gravitationally, so they feel gravitational pull towards each other and they cluster. It’s the clustering of the dark matter, the fact that it gets compact, that we detect the effects of dark matter.

M&B: What happens near the regions where dark matter clusters? In your research papers you use the bending of the light rays. How do you observe it?

The primary evidence is the gravitational bending of light produced by these aggregates of dark matter. The universe is really composed of a smooth distribution of dark matter, with a lot of clump regions where this dark matter has aggregated, and then enabled the formation of galaxies. The presence of these large amounts of dark matter causes light from background galaxies coming towards us to bend. The actual shapes of galaxies that are behind a big clump of dark matter, which is along our line of sight, are actually distorted when we see it. The dark matter in general is smoothly distributed everywhere in the universe. But there are these particular regions that are denser. So we can look at regions in which the dark matter is not so densely distributed, look at the shapes of undistorted shapes of galaxies, and then use that to infer how much distortion we’re actually seeing when we see a lump, and infer its existence from the distortion. Because the strength of the distortion is directly proportional to the mass, you can directly infer how much mass there is between us and those objects.

M&B: Is there evidence other than the bending of the light rays?

The other evidence eludes to the fact that dark matter actually gives the basis for the formation of stars and galaxies. If you look at the motions of stars and galaxies, you find that, unlike the solar system, if you look at the velocities of the planets in the solar system as a function of distance from the sun you find that it’s falling. So the planets in the inner regions are moving very fast; they feel the gravity of the sun much more strongly than the outer planets, which are not actually moving as fast. So if you plot the velocity from the center or from the sun outwards in the solar system, the velocities are falling. Whereas if you go to a galaxy and you do the same experiment, you look at stars at different radii and you try to see what their speeds look like. They are speeding up as you go outwards. And the only way they can do that is there is something that is sitting outside the galaxy that holds it up as it were, and has gravity. And it turns out that our current picture is that most galaxies have very extended dark matter halos. The key point is that there’s a lot of dark matter sitting outside the galaxy well beyond where we see the stars.

The other compelling lines of evidence for the existence of dark matter come from larger scale observations of the universe. One of the leftovers of the big bang or relic of the big bang is this microwave background radiation that is detected today in the universe. It was a very hot radiation that has cooled with the expansion of the universe, and we are bathed in it. I mean it’s everywhere, in every direction, and measurements of the directional dependence of the microwave background shows that it’s very uniform. But in one part it’s anisotropic, so there are cool zones and hot zones in the sky. On very small scales we see these cold and hot spots. And these and isotropy’s in the microwave background are exactly predicted by this model, the cold dark matter model, which I said you know is postulated on the very early generation of the universe and these dark matter particles.

M&B: So we know that they exist. But what is their essence? What are their properties?

This is still a mysterious kind of beast. In fact, we don’t know the nature, but it appears that it’s collisionless. It’s very counterintuitive. That’s one of the things I find fascinating about the fact that it is so counterintuitive. These particles are actually collisionless. What that means is that when two dark matter particles approach each other, they pass through each other, they don’t actually bounce off of each other, so these particles don’t collide, which means they don’t have pressure, because pressure is generated by collision. So they are pressureless particles that have mass. Gravity holds them together, but they don’t actually collide.

So a current understanding of dark matter is that it’s definitely generated very early in the universe and that it clusters very strongly and it’s distributed on very different scales in the universe, so there’s like a smooth background and there are lots of clumps on top of it and so on.

M&B: As far as the mass of Dark Matter how much mass are we talking about? If there is no clustering, something like in the volume of the earth, for example, how much total dark matter mass do we have?

Well I guess the thing is at the position of the earth and at the position of the sun from the center of our galaxy. We are not really dominated by dark matter anymore, so dark matter at that radius doesn’t constitute significant portion of the mass. We are bathed in it, but the density is quite low. It’s at the innermost part of our galaxy where the density is very, very high, so we actually expect that the inner most regions of our galaxy is a very complicated, violent place where not only do you have a black hole which we know exists. This is a black hole that is not made of dark matter. This is a black hole that has gobbled gas and grown to about a million times the mass of the sun, and which is sitting at the center and it creates a very violent place for stars because it can rip them apart and so on. And this whole system is sort of embedded in this very, very dense region full of dark matter.

M&B: How is your everyday work? Where do you get data about the light rays coming near the regions with high Dark matter density?

A: I’m a theoretical person and what that means is that I actually build models but models that are guided by observations. The theory has transformed in the past 10 to 15 years because of the amount of data that technological progress has given us.

For example, the Hubbell space telescope has really transformed the kind of modeling that can be done. So I actually use data that other people have procured. They’ve cleaned it up and they give it to me. These are very distorted images of background galaxies whose shape has been distorted because of the huge amounts of dark matter that is contained in a cluster of galaxies.

M&B: The bending of the light rays is predicted by the general relativity theory. Is it what you use for your calculations?

A: It’s a beautiful theory. I think that people really have understood the iconic status of Einstein. What is most fascinating about him for me is the profound insights that he had of such despaired phenomenon. There was a way in which he was able to see connections and synthesize. You know the whole understanding that the geometry, the fate and the contents of the universe ought to be linked is a profound insight. And I think you know it’s incredible that he enabled, you know, his mind enabled him to formulate it in the way that he did, which has allowed people like me to use general relativity and the sort of elegance of general relativity because of how simple it is in fact to apply and test.

M&B: This looks like an intriguing line of work?

I want to stress that this is a particularly wonderful time for cosmology. It’s a particularly special time. I don’t want to use the sort of often abused golden age as it were, but it’s the confluence of technological progress with the kind of data that we can obtain and the level of understanding that we have built up. This is a very special time to be doing this kind of work. And while the mystery of what dark matter might be made of, you know, it may or may not get solved in my lifetime.

M&B: If you want to describe your work, what term would you use?

In a more descriptive way, I guess. What I really do is I build a story line. I build a story line for the universe. I mean, I build a story of the sequence of events of how a structure forms and assembles. The key there is that you are guided, you have a few snapshots, so you have a bit of data, but then you have to extrapolate and you make some predictions. The goal of the kind of work that I do is to make predictions, and have them be taken seriously, to either be falsified or shown to be true, and what’s exciting about this particular time is that people can falsify your theories or your models in a very short time.

M&B: Isn’t it interesting that we can actually make a story out of universe?

Well, I mean, I think that what is fascinating, and this is a personal view, what is fascinating about cosmology is the… you know it’s mystical and it’s mysterious at the same time and it’s highly abstract. It’s not intuitive because the scale that I’m working with in terms of distances, masses, and energy are just unfathomable. So there’s a real irresistible pull for certain kinds of people to do this kind of work. And I think the universe is a pretty good subject for a narrative because of the range of phenomena that occur in it. This is possibly why in all ancient civilizations there is some notion of cosmogony and this idea of fascination with where we came from. I don’t want to sound arrogant by saying that it’s the fundamental question, but you know it’s an inescapable question for anybody to ponder where we came from.

M&B: Is there a sense of awe that motivates you in your studies?

There is a sense of wonder that the universe generates and I think that you know personally for me I’m a bit of an adventurist, and I think if I can imagine myself, if I had been born 200, 300 years ago I would have been one of those explorers. And I think there are people like that amongst us always, who want to explore in different ways. I mean, there are some people who want to explore via music. And there are frontiers that they want to break through in music, and they have the creativity to do that. And I think that for a lot of us who are doing science, and cosmology in particular, there is a sense of exploration, there’s a sense of examining or grappling with things that are really at the limits of our capabilities in a way.

M&B: In some ways one of the most important fruits of the process and coming along it’s our imagination. And the human imagination is also a part of the universe.

Absolutely. It is an inescapable part of the universe and what is fascinating is the idea that we have the capability to even contemplate the origin of the universe given that we are a part of the universe.

M&B: Many people approach science in a utilitarian way and this is not what you are doing.

I think that the fact that it is not utilitarian is precisely what attracts me to it. I think it is the other side of the coin of this, which is why we probably aren’t as well funded and we ought to be better funded than we are, because this is such a fundamental human curiosity. There is enormous public interest in what we do and the level of funding that we have does not reflect that. For instance, obviously medicine is very critical. It’s critical to our existence. But the disparity in how they are funded and how the pure sciences are funded is sort of disturbing. Because I think as a culture, as a world, we can afford to indulge in understanding basic sciences partly because there are spinoffs from all the work that we do. It is unpredictable, and I think that is what’s fascinating. There are no guaranteed benefits to human kind and society today that cosmologists can bring. However, they satisfy this hunger for knowing and going beyond, you know, satisfying your hunger and thirst on a day to day basis.

Mustafa Tabanli is a producer at Ebru TV. He conducted this interview for Emmy Award winning television series Matter&Beyond.

Bio

Dr. Priya Natarajan is a Professor of Astronomy and Physics at Yale University, and an Associate at the Dark Cosmology Center, which is part of the Niels Bohr Institute at the University of Copenhagen, Denmark. Her research interests include cosmology, gravitational lensing, and black hole physics. She earned a B.A. degree in physics and mathematics at M.I.T. and her doctorate at the Institute of Astronomy, University of Cambridge in England, where she was a member of Trinity College and elected to a Title A Research Fellowship that she held from 1997 to 2003. She is currently on leave from Yale to take up her Guggenheim Fellowship. She is deeply invested in the public dissemination of science and is currently a member of the Science Advisory Board for the public television series NOVA.

http://www.astro.yale.edu/priya/