Jeff Silverman and Nicholas McConnell helped Spectrum present a three part Astronomy survey explaining the ideas, experiments, and observation technology that are transforming Astronomy. This is part three of three. We discuss Dark matter and dark energy.
Transcript
Speaker 1: Spectrum's next
Speaker 2: [inaudible].
Speaker 1: Welcome to spectrum the science and technology show on k a l x Berkeley, a biweekly [00:00:30] 30 minute program bringing you interviews featuring bay area scientists and technologists as well as a calendar of local events and news.
Speaker 3: Hello and good afternoon. My name is Brad Swift. I'm joined today by spectrum contributors, Rick Karnofsky and Lisa [inaudible]. Our interview is with Dr Jeff Silverman, a recent phd in astrophysics from UC Berkeley and Nicholas McConnell, a phd candidate, unscheduled to be awarded a phd in astrophysics by UC Berkeley this summer. [00:01:00] Jeff and Nicholas have been helping spectrum present a three part astronomy survey, explaining the big ideas, recent experiments, collaborations and improvements in observation technology that are transforming astronomy. This is part three of three and we discuss dark matter, also known as dark energy. Before we talk about dark energy, let me ask you, how do you
Speaker 4: relate to time, the human lifetime and then universe lifetime as a scientist [00:01:30] and as a human being, how do you do that? How do you make that stretch? I can't say that I necessarily have an intuitive sense for just how much time has elapsed between the dawn of the universe and me. But I think you can extend it a little bit. You can think of your parents and your parents' parents. And the idea of having ancestry and lineage as a person is a fairly familiar concept. And so I'm the product of generations of people who have done things. And similarly our planet and the conditions that we have and experience every day [00:02:00] are the product of generations and generations of stars being formed and galaxies being formed throughout the universe. And so I think this idea of generations where one thing spawns another and conditions change slightly and gradually over time, but some of the same processes like new stars forming happen over and over and over again is one way to sort of access the, the notion of time throughout the universe.
Speaker 5: I think one of the hardest issues for astronomers in astronomy research in general [00:02:30] is the further away we look, the further back in time we look. As Nicholas mentioned, it takes light time to get to us. So if you look at something very far away, it looks like it did much younger in the past, but we can't just watch two galaxies collide and merge. We can't watch a cloud of gas collapse on itself and form a new star and then evolve and then explode as a supernova. We can't wash those processes. We get a snapshot in time, affectively a still of all these processes [00:03:00] all over the universe at different stages. And then the astronomers have to put these pictures in the right order of what's going on, which picture corresponds to which age and how you go from one to the other. And I think that's something that I've had trouble with trying to think about it.
Speaker 5: You know, I want to sit down as a scientist and just watch a star evolve and watch it grow up and then die. And then you take your notes and figure it out. Then you're lucky you do get to actually watch them die. I do watch the dying part and you know, with Supernova, with certain kinds of astronomy of phenomena, we [00:03:30] can watch things change on a reasonable basis, on a daily, monthly, yearly basis. But that's the very last bit of a star that has maybe lived for 10 million years or 4 billion years. And one of the things we tried to do is by looking at the death in for a lot about the life, but it is only that small part portion. And there's lots of astronomy where it is basically static and you just see the same thing without any kind of change. There are certain parts of astronomy that do change a little bit with time and we can learn from that. [00:04:00] But the bulk of the star's life, we don't see any change or we just see that tiny bit at the end.
Speaker 6: This is spectrum on k a l x Berkeley. We're talking with Dr Jeff Silverman and Nicholas McConnell, astrophysicists from UC Berkeley talking about dark energy. [00:04:30] Let's talk about dark
Speaker 4: dark matter. And in so doing, talk about how dark energy or dark matter have become important to astronomy. So one of the interesting things that's happened over the past say half century is that we've profoundly changed our perspective of what the universe contains and what it's fundamentally made of. And so Jeff mentioned through the Supernova in the late nineties we discovered that the universe was expanding faster [00:05:00] and faster and faster. And we think that is due to something that we refer to as dark energy, which we believe makes up about 70 75 5% of the overall mass and energy in the universe. And then when we look at things that we think are sort of more classically as matters stuff that admits gravity and causes things to orbit around it, we've also learned that a very large percentage of gravitational stuff in the universe is made up of this mysterious stuff called dark matter that we know is there [00:05:30] in very large quantities.
Speaker 4: It dominates the gravity of how galaxies, for instance, interact with one another. However, we don't know what it's made of. Unlike other kinds of matter, it doesn't emit any light whatsoever. So using telescopes we can learn very little about its actual composition. But on the other side of physics and astronomy, particle physicists have been coming up with theoretical models of the various subatomic particles that constitute universe. And there are certainly space in those [00:06:00] particle models to have particles that are responsible for creating the dark matter. But even though there are a bunch of theories that describe what this dark matter particle might be, it's still not constrained by experiment. We haven't detected definitively any dark matter particle yet, but there are experiments ongoing that are trying to determine what some of these very fundamental particles are. And one that I'll mention because it's led at Berkeley and had an interesting, although definitely not definitive result a couple of years ago is called the cryogenic [00:06:30] dark matter search or cdms.
Speaker 4: Uh, and this is an interesting experiment that takes tablets of pure Germanium and buries them, deepen a mine in Minnesota with a lot of equipment and the Germanium is cooled to almost absolute zero as close to absolute zero as we're technologically able to get it. And just sits there waiting for a dark matter particle to come along and collide with one of the atomic nuclei in one of these tablets and the thing about these theorize dark matter particles is that they're extremely noninteractive [00:07:00] to a certain degree. The earth and the galaxy are swimming in a sea of dark matter particles, but they pass through us and never have any noticeable effect on us almost entirely all of the time, but on very, very, very rare occasions you actually do get an interaction in principle between a dark matter particle in something else and so we have these tablets just sitting there waiting for one of these collisions to happen so that we can detect it.
Speaker 4: Now there are a bunch of other things that cause collisions in Germanium, things like cosmic rays, which you kind [00:07:30] of get out of the way of by bearing a deep underground electrons and light from other sources, radioactive decay, all of these can set off signals that with a lot of processing and principle, you can distinguish from the ones you expect from having a dark matter particle. Anyway, in 2009 CMS released a statement that they'd been collecting data on collisions inside these tablets for roughly a year's time period and what they found was that based on the best efforts they could do between weeding out [00:08:00] all of the background sources that they're not interested in, they estimated that they would have one false detection that on average statistically they would have missed one background source and classified as a real source. I mean in that same year time period they had found two detections.
Speaker 4: So in a very, very, very non-statistical sense, you say, well we found two and we think that one of them statistically is probably false. Maybe we found a dark matter particle. Of course, this is far below the standards of rigor that science requires [00:08:30] for actually saying, yes, we found dark matter, but it's an interesting start and there are certainly ongoing experiments to try to detect these very, very rare interactions between the mysterious dark matter that makes up most of the gravitational stuff in the universe and the ordinary matter that we do know about that. For the large part, it never actually does get to experience it. Are Neutrinos part of dark man or is that another issue entirely? Neutrinos. So I think that some of these particle models suggest that the dark [00:09:00] matter particle is what's called a super symmetric version of a neutrino. So something that has a lot of similar properties to a neutrino but is much, much, much more massive than neutrinos that we do know about have almost no mass whatsoever similar to the dark matter. They also almost never interact with ordinary particles, but there were models run basically saying how would the universe evolve and what would it look like today if dark matter were made up of these neutrinos that we do know about. And those models predict the [00:09:30] overall structure of the universe being very different from what we observe. So we're pretty sure that neutrinos are at most a very small fraction of this dark matter.
Speaker 5: Yeah, getting talking a little bit more about the neutrinos. As Nicholas said, they probably are not a huge component of what classically we're referring to as dark matter and that these big experiments are looking for, but they are very interesting weird particles that don't interact very much. They're very hard to detect. They're going through our bodies all the time. The Sun produces them a supernovae produce them [00:10:00] in large amounts as well and even though they're not rigorously really much of this dark matter, they are very interesting and large experiments around the world have been conducted over the past few years to try and detect more of them, to try and classify them and learn more about these neutrino particles. One that Berkeley is very heavily involved in in the, in the Lawrence Berkeley lab is called ice cube down in Antarctica actually. So if you're a poor Grad student in that group, you get to a winter over for six months in Antarctica with lots and lots of DVDs is what I've been told.
Speaker 5: [00:10:30] But basically what they do down there is they drill huge vertical holes into the ice shelves and drop down detectors, a photo multiplier tube type devices, things that should light up if they get hit by a neutrino or something like that. And they do a ton of these at various depths and make a greed under the ice. A three dimensional cube under the ice of these detectors could imagine a cubic ice cube and you poke one laser beam through [00:11:00] it. You'll light up a bunch of these detectors in the line and you can connect all of those points with a straight line and sort of see where it's coming from in the sky. And so connecting back a little bit to supernovae. If the Supernova goes off very, very close by, we could possibly detect neutrinos from some of these supernovae and perhaps little deviations from where it goes through and which detectors that lights up could be telling us some interesting information about the neutrinos that are produced in the supernova about our detectors.
Speaker 5: So it's a very nice, uh, play back and forth. [00:11:30] Ice Cube has not found neutrinos from a supernova yet. Hopefully we'll have even closer supernovae in the near future and ice cube and other types of neutrino experiments. We'll see possibly some of these and so another great example of big international collaborations even from different types of physics and astronomy getting together the supernova hunters and Supernova Observer, astronomers talking to these neutrino detector particle and trying to come together and answer these questions about the universe from two different sides. Basically two different kinds of science [00:12:00] almost, but coming together with similar observations or related observations is a very interesting prospect.
Speaker 6: The show is spectrum. The station is KALX Berkeley. We're talking with Dr Jeff Silverman and Nicholas McConnell there explaining dark matter, dark energy,
Speaker 7: dark matter and dark energy as [00:12:30] you called it. Are there other experiments and avenues of research for uncovering this phenomenon or particle, however you want to refer to it?
Speaker 8: The direct particle detection experiments that are on earth and we mentioned one of them led by Berkeley are probably the main avenues we have right now for discovering what particle is responsible for the dark matter. There are other ways that we can still collect additional evidence, [00:13:00] although we already have quite a bit for the fact that some strange particle and not ordinary protons and neutrons and electrons are responsible for a lot of the gravitational forces that we see in the universe. One other avenue that might be interesting is the idea that if dark matter is made of subatomic particles, there could be cases where two of those particles interact with one another and Gamma Ray radiation by annihilating them and in that case we have [00:13:30] gamma ray telescopes set up in space that spend a lot of their time detecting more prosaic Cammeray sources. Things like exploding stars, but it's possible perhaps in the near future that these telescopes can also detect gamma ray signatures from the centers of galaxies that we would be able to analyze in such a way that we determined was more likely to be from dark matter particles annihilating one another than from these other astrophysical sources that we already know about.
Speaker 8: I'm not sure if that would reveal the identity [00:14:00] of what the dark matter particle is, but it would be more evidence that they do exist.
Speaker 7: Dark matter has been hypothesized so that the theory of relativity works or is it devised to prop up the standard model,
Speaker 5: the strongest pieces of evidence for the existence of dark matter and sort of the reason that we added it into our pictures of the cosmos is there's not enough stars and gas in galaxies. If you [00:14:30] add up all of the gravity, it's not enough gravity force to hold all those stars and gas together in a galaxy and so we need some other matter that exists that exerts the gravitational force to hold everything together, but it doesn't glow. It's not bright. We can't see it with our normal telescopes at any wavelengths in space or on the ground. And so we've sort of given it this name, dark matter, these dark particles that exert a gravity force but don't give off light in any sense of that word. [00:15:00] We found some candidates over the years. Those have been interesting but they don't add up to enough matter out there and so we hypothesize that there is some other particles, something we haven't figured out yet in particle physics since that is out there and we're not detecting it with our telescopes, we're not detecting it with these other experiments that find subatomic particles and I can see very rare subatomic particles, but I personally think in the next decade we will directly detect one of these particles or a handful of these [00:15:30] particles.
Speaker 5: If we don't with these experiments that are online and coming online. If we don't detect these dark matter particles then we're going to have to really rethink how these galaxies, our own galaxy included can exist in their current form with all their stars and gas that we can observe. There'll be some serious issues in our understanding of galaxies and the study of the universe in general, but I think we will find dark matter particles. I think it will match to at least some of the models and theories we have and I like to think that everything is nice and [00:16:00] ordered in. That gives me comfort when I go to sleep at night.
Speaker 7: So on that personal level and trying to understand the standard model and your confidence in all that, is there a part of you that's open to the idea that it may not really be as you've as has been imagined for the past 30 years?
Speaker 8: I think that at one level of detail or another it's actually very likely that the models we've constructed over the last century, in the case of particle physics in the last 30 years, in [00:16:30] the case of adding dark matter as an ingredient to the universe that we see as astronomers, I think it's very likely that some of those details are going to fall by the wayside and be replaced by a different and more accurate description that people aren't thinking of yet. I think if the history of science teaches us anything, it's that as soon as we get over confident that we've put all the pieces together. If something comes in really forces us to rethink how the universe works as far as dark matter goes. I'd like to point out that there's sort of two [00:17:00] different theories in play and that either one of them I think could be revised in order to explain observations if we do fail to detect dark matter particles soon.
Speaker 8: And one of them is Einstein's theory of relativity saying that if we know how much stuff there is that we actually understand the literal force of gravity well enough to determine how mass interacts with one another and how the force of gravity works. And then the other one is different particle physics theories that say that if you have stuff coming and gravity like a dark [00:17:30] matter particle, what are the, the limiting things for what that particle could actually be. And I'm not well versed enough to know whether there's a lot of room for dark matter particles to exist that we wouldn't be able to detect with this generation or the next generation of experiments. But one possible way to fail to detect matter particles now and not have to revise general relativity as if particle physics can come up with a particle that is responsible for dark matter but is well beyond our capacity to detect [00:18:00] at this point.
Speaker 3: Nicholas and Jeffrey, thanks very much for coming on spectrum. Thanks for having me. Thanks for having me.
Speaker 6: For people who are interested in getting involved in amateur astronomy, let me mention a few avenues to pursue. The astronomy connection has a website that will lead you to a wide range of observing individuals and groups in the bay area. Their website is observers.org [00:18:30] for those who want to get involved in a crowdsource astronomy project, go to the website, Galaxy zoo.org the University of California observatories have a website that has a great deal of information, particularly under the links heading. Their website is used, c o lik.org or [00:19:00] regular feature of spectrum is to mention a few of the science and technology events happening in the bay area. Over the next few weeks. I'm joined by Rick Kaneski and Lisa Katovich for the calendar.
Speaker 9: The science of art is the spring open house at the crucible. This event we'll highlight the scientific principles, inquiry and exploration behind the fine and industrial arts processes taught there. This event will bring together crucible faculty, guest artists, and a curated gallery of exhibits and demonstrations. Also projects from local schools [00:19:30] as well as special performances, food and the participation of a number of other local art and science related organizations and university programs. This event will happen on Saturday, April 7th from 12 to 4:00 PM and the crucibles located at 1260 seventh street in Oakland.
Speaker 3: The Oppenheimer Lecture, the Higgs particle pivot of symmetry and mass. The Speaker is [inaudible] to [inaudible] professor of theoretical physics [00:20:00] at Utrecht University in the Netherlands. Professor to Hoeft was awarded the Nobel Prize in physics in 1999 in this lecture, professor to Hoeft will reflect on the importance of the as yet undetected Higgs particle and speculate on the Subatomic world once the particle is observed in detail. The lecture is April 9th at 5:00 PM in the Chevron Auditorium at International House [00:20:30] on the UC Berkeley campus. On Monday, April 9th the Commonwealth Club of San Francisco at five nine five market street is hosting Barb Stuckey, the author of taste, what you're missing. The passionate eaters guy too. I good food. Tastes good. Some reviewers say that this book bring science to the of taste. In the same
Speaker 10: way that Harold McGee's book on food and cooking popularized food science. She will talk about understanding the science and senses of what you eat. You'll better understand both the psychology and physiology of taste [00:21:00] and learn how to develop and improve your tasting pellet by discerning flavors and detecting and ingredients. A five-thirty checkin proceeds. The 6:00 PM program, which is then followed by a book signing at seven the event is free for members, $20 standard admission and a $7 for students. Visit www.commonwealthclub.org for more info
Speaker 9: pioneers in engineering. A nonprofit high school robotics competition organized by UC Berkeley students is holding its fourth annual robotics competition. [00:21:30] The Big Day is Saturday, April 14th at the Lawrence Hall of science in Berkeley. The competition begins at 10:00 AM and continues all day until five. This year's challenge is titled Ballistic Blitz for the seven weeks leading up to the final event. 200 high school students in teams from 21 East Bay high schools each work to design and build a robot. Come see the dramatic culmination of their hard work. This event is included in the price of admission. Admission is [00:22:00] free for UC Berkeley students and staff. For more information, go to the Lawrence Hall of Science website and Click on events. Mount Diablo Astronomical Society presents member planets, our solar system, neighbors, Venus and Mars through telescopes and find out why earth has abundant life but not Mars and Venus. Saturday, April 14th 7:00 PM to 11:00 PM the rendezvous is at Mount Diablo lower summit parking lot [00:22:30] summit road.
Speaker 9: Clayton. For more details and contact information, go to the website, m d a s. Dot. Mitt. On Wednesday, April 18th ask a scientist. A monthly lecture series will be co launching the wonder Fest Book Club with USI Professor, biological anthropology and neuroscience, Terrence Deacon's book, incomplete nature, how mind emerged from matter. Professor Deacon's presentation will focus on the idea that key elements of consciousness, [00:23:00] values, meanings, feelings, etc. Emerge from specific constraints on the physical processes of a nervous system. The lecture will be located at the California Institute of Integral Studies at Namaz Day Hall, 1453 Mission Street in San Francisco. It will start at 7:00 PM and it's free.
Speaker 10: Cal Day, UC Berkeley's free annual open house will be on Saturday, April 21st 9:00 AM until 4:00 PM there'll be a ton of science related events this year, including [00:23:30] tours of the labs and shops used for molecular and cell biology, synthetic biology, mechanical engineering, Quantum Nano Electronics, space sciences, star dust, nuclear engineering, automation, science, and more. There'll be lectures on diverse topics such as environmental design, geology, and the art and science of prehistoric life, as well as tables for various science and engineering majors and student groups. For more information. Visit [inaudible] dot berkeley.edu [00:24:00] now on to the news,
Speaker 9: a February NASA study reports that climatic changes in the polar regions are occurring at a magnitude far greater than the rest of the planet. The oldest and thickest Arctic Sea ice is disappearing at a faster rate than the younger and thinner eyes at the edges of the Arctic oceans floating ice cap, the thicker ice known as multi-year ice survived through the cyclical summer melt season when young ice that has formed over winter. Just as quickly melt again, [00:24:30] Joey Comiso, senior scientists at NASA Goddard Space Flight Center and author of a study recently published in the Journal of climate says the rapid disappearance of older ice makes Arctic Sea ice even more vulnerable to further decline in the summer. The surface temperature in the Arctic is going up, which results in a shorter ice forming season. It would take a persistent cold spell for most multi-year CIS and other ice types to grow thick enough in the winter to survive the summer melt season and reverse the trend. [00:25:00] This warming in the Arctic is the warmest 12 month on record. For the region. This means that the region is moving closer to, if not already, breaching climatic tipping points which could see the Arctic's current ecological state being shifted to an entirely new one, having severe ramifications, not only for the biodiversity and ecosystems of the region but also for the rest of the planet.
Speaker 10: The April 2nd issue of the proceedings of the National Academy of Sciences has an article by Francesco Burma of Boston University [00:25:30] and others that reports evidence that humans acquired fire at least 200,000 years earlier than previously believed. The evidence is in the form of sediments from the wonderware cave in the Northern Cape province of South Africa. They were studied by micro morphological and foray transform infrared micro spectroscopy and data to be 1 million years old. The sediment contained burn, sharp bone fragments and plant ashes. The bone seems to have been exposed to temperature is found by a small cooking fires under about [00:26:00] 700 degrees Celsius. Previous to this finding, there was consensus that the earliest fires dated to only 790,000 years ago, and so these reporting older fires tended to be controversial as it is difficult to demonstrate that fires were small and intentional and use for cooking rather than acts of nature.
Speaker 9: More than half of all cancer is preventable. Experts say science daily reports that in a review article published in Science Translational Medicine on March 28th the investigators outlined obstacles. [00:26:30] They say stand in the way of making a huge dent in the cancer burden in the u s and around the world. Epidemiologists, Graham Colditz, MD professor at the Washington University School of Medicine and associate director of prevention and control. The Siteman cancer center says, we actually have an enormous amount of data about the causes and preventability of cancer. It's time we made an investment in implementing what we know. According to the American Cancer Society, an estimated 1,600,000 new cancer cases will be diagnosed this year in the u s [00:27:00] also this year, approximately 577,000 Americans are expected to die of cancer according to Kolditz and his co authors individual habits and the structure of society itself from medical research, funding to building design and food subsidies influences the extent of the cancer burden and can be changed to reduce it.
Speaker 10: Science news reports on a paper presented at the cognitive neuroscience society by Andrew met her, Ellie, Mika, and CN Beilock. [00:27:30] Both of the University of Chicago. The team use brain scans to find areas in a person's brain whose activity you will predict how well that person functions under pressure. Using functional magnetic resonance imaging, the team gave both low and high stakes math problems to volunteers. Stakes were determined by both the size of financial reward and a social pressure via a financial penalty imposed upon teammates. In the case of failure, well, easy questions could be answered regardless of the stakes in the study. More difficult [00:28:00] questions led to a 10% average decrease in performance for volunteers who had decreased performance. There is greater activity in the enterprise [inaudible] circus and the inferior frontal junction of the brain area is linked to working memory. Furthermore, the more the ventral medial prefrontal cortex and area linked with emotions work to keep these two areas in sync, the more likely the volunteer was to choke under pressure.
Speaker 2: [inaudible]
Speaker 6: [00:28:30] a special thanks to Dr Jeffers Silverman and Nicholas McConnell for spending the time with us. Degenerate three shows on astronomy. Thanks to Rick Karnofsky who helps produce the show and Lisa Katovich for her health
Speaker 2: [inaudible]
Speaker 6: the music heard during the show is by Los Donna David and album titled Folk and Acoustic [00:29:00] made available by a creative comments 3.0 attributional license.
Speaker 2: [inaudible]
Speaker 6: thank you for listening to spectrum. If you have comments about the show, please send them to us via email. Our email address is spectrum dot k@yahoo.com join us in two weeks at this same [00:29:30] time.
Speaker 2: [inaudible]
Speaker 11: [inaudible].
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