Dialog Questions
From the following set of questions each team should select one question as the subject for the dialog in their team project. Two teams may not select the same question. Therefore, the first team requesting a particular question will be assigned to that question, and subsequent team requests will be told to select another question.
| Violet | Blue | Green | Yellow | Orange | Red |
| 1. | Chemical Evolution and Structure of Matter |
| Although, general agreement exists in the scientific community in favor of the "atomic structure of matter," differences in understanding do exist in the ultimate divisibility of constituent particles such as protons and neutrons. Additionally, general agreement exists that the currently observed abundance of the chemical elements in the universe is one that has been achieved through evolution from "simple" elements through the process of thermonuclear fusion in the life cycle of stars. However, what is the origin of those "simple" elements? How many "simple" elements are necessary? Also, do we really understand thermonuclear processes if the observed solar neutrino flux is smaller than theoretical predictions? Is the time scale for the production of the observed abundance of the elements consistent with elapsed time if the universe is an evolutionary one? Does the supernova explosion by massive stars account for both the abundance and galactic distribution of the elements? Can we be confident in our understanding of chemical evolution when the question of dark matter is not settled, since dark matter may constitute as much as 27% of the mass-energy in the universe? Is it possible and by what mechanism could dark matter be either responsible for or a significant contributor to chemical evolution? Finally, in recent years, we are confronted with the acceleration of the expansion of the universe by dark energy. Could dark energy, if real, influence chemical evolution by controlling the spacing between reacting particles or in some other manner? Participants: 
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| 2. | Large-Scale Structure of the Universe |
| From the first use of the telescope for astronomical purposes, we have known that clustering of galaxies exists even if we were not sure that galaxies were separate entities from our own Galaxy. Since our Galaxy blocks roughly 20% of the entire sky from detailed investigation, is it possible that the other 80% does not give us an accurate picture of the large-scale structure of the universe? Although, there is general agreement that clustering of galaxies occurs on a range of scale sizes, why should we believe that clustering is not present on the largest scale sizes, but that the Universe becomes homogeneous and isotropic as stated in the Cosmological Principle? If the Universe is an evolutionary one, when and how did the observed large-scale structure impose itself? On the other hand, if the history of the Universe extends to the infinite past and the infinite future and the large-scale universe remains pretty much the same over time, why does any significant clustering of galaxies occur at all? Finally, dark matter makes its presence known only through its gravitational effects, and it may constitute 90% or more of all matter in the Universe, and its nature and distribution in the universe are not known. Thus, how can we have any confidence that we not only can recognize the large-scale structure of the universe, but also understand how it was achieved? Participants: 
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| 3. | Gravity as the Source of Motion and Structure in the Universe |
| The "falling body" is one of the most common of all human experiences, but understanding its details and the reasons behind that behavior continues to perplex science today. The historical evolution from Aristotle's "like-seeking-like" explanation, to "action-at-a-distance," to Newtonian gravitational fields of force, to Einstein's general relativity and its many variations, to particle exchange, there has been an increasing emphasis on what is the means of communication between bodies such that they can mutually influence each others motion as clearly they do. It is motion, along with the nature of space and time in which that motion occurs and the material structure of moving bodies, that is at the heart of our understanding of physical existence. And, it is the various scales of structure from atomic to the universe itself that are the consequence of what motion is and is not. But, what distance for gravitational interaction determines various scale sizes of organization and structure? If space is growing all the time, as we agree that it is, will gravity become less and less effective in imposing structure on the universe? Why does motion, like the proverbial "bull in the china shop," not destroy all structure reducing the universe to smoothed-out rubble? Or, will gravity cause everything to coalesce into one or several great bodies? If 90% or more of the matter in the universe is dark matter, what is its role in controlling motion and determining the structure of the universe? Finally, why is a limit imposed on the speed at which bodies can move relative to each other and what is the subsequent consequences of that limitation? Participants: 
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| 4. | Nature of Space and Time |
| The historical evolution of conceptual understanding of space from being a gulf of nothingness that separates pieces of matter to our present understanding that space is a physical entity possessing a host of properties has been a fascinating journey. Our ideas of space and time are intimately connected with concepts of motion. Since motion can be both forwards and backwards, why does our experience with time show us that it advances in one sense, past to future, when the mathematical expressions for physical laws work perfectly well if time goes backward? Where is that experience of time running the other way? Why does our experimentation with motion tell us that space can have a far more involved geometry locally than the simple Euclidean geometry of our everyday experience? On the global scale of the universe, does space also possess non-Euclidean geometry different from that of local space? If so, why are they not the same? If the human mind can fashion geometries that are extremely different from that of experience, why does the universe not display these to us – are we not part of the universe? Certainly, our observation of the large-scale nature of space suggests that if it is not Euclidean it is not far from it. Or, is it and we do not recognize such is the case? Also, our minds can produce a world of many more spatial dimensions than three, why then do we not experience them? Participants: 
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| 5. | Steady State and Evolving Universes |
| The historical contest between the Greek idea that time is infinite into the past and infinite into the future with a universe that remains approximately the same, known as the Athens Hypothesis, and the idea that time is not infinite into the past but finite with a universe that experiences continuing change, known as the Jerusalem Hypothesis, has in many respects shaped the development of intellectual thought over the last 2500 years, particularly in the Western World. In the interval, we have refined, modified, and augmented these two notions of the nature of the universe, but cosmology is still pursuing the definitive argument that will allow us to finally settle the question of which is correct. Is new thinking about and observations concerning the structure of the universe actually changing the nature of the debate about the Athens and the Jerusalem hypotheses? What are the consequences for the existence of life, such as us, imposed by different cosmological models? In an evolutionary universe, the laws of physics could have an origin and could conceivably change over the course of the evolution of the universe. Do we address such possibilities in our study of the universe in cosmology? And, what are the consequences of changing physical laws on the existence of intelligent life as we understand it? What evidence do we have today that favors one cosmological model over another? Does that evidence allow us to eliminate with great confidence one or the other of the many possibilities for a cosmological model? Participants: 
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| 6. | The Early Universe and the Expansion of Spacetime |
| As recently as twenty years ago, almost no one could envision that in a very short period we would be well along in our understanding of the early universe that was produced by the initiation of the expansion of the spacetime continuum. How definitive is the observational basis for the current expansion of spacetime? Are there possibilities that alternative interpretations of the observations exist besides the expansion of spacetime? Keep in mind that there is no early universe if spacetime is expanding. New technologies have made possible over the last twenty years or so the mapping of the Cosmic Background Radiation (CBR) in conjunction with observations of supernovae outbursts, galaxies, clusters of galaxies, and large scale structure at reasonably large redshifts (earlier periods in the history of the universe). What evidence do we have that all the laws of physics may not be known or that they have changed sufficiently over time that we are unable to actual interpret the observations from the new technologies? What do these various categories of studies reveal about the early universe? Does the mapping of the CBR give us true incite to the early universe? How much is our interpretation of the early universe predicated on theoretical cosmological models? Are there conflicting results concerning a discrimination between cosmological models? What is the possibility that our understanding in cosmology is not even close to a “real universe” assuming such a thing actually exists? Participants: 
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