Empiricism and Rationalism in the Advancement of Astronomy
Odysseus Quarles
Undergraduate Honors Thesis in Astrophysical and Planetary Sciences University of Colorado Boulder
Thesis Defense Date: March 20, 2018
Advised by:
Thesis Advisor: Asst. Prof. Dave Brain, Ph.D. Department of Astrophysical and Planetary Sciences
Honors Council Representative: Asst. Prof. Ann-Marie Madigan Ph.D. Department of Astrophysical and Planetary Sciences
Third Reader: Assoc. Prof. Dominic Bailey, Ph.D. Department of Philosophy
Abstract
Astronomy is advancing quickly, with resources being allocated to the cutting edge of our understanding of the universe while the more basic understanding and confirmation aspects of astronomy research are still underway. Research in both areas is conducted according to two differing philosophies of knowledge: empiricism, which holds observation and direct experiment as the most reliable source of information, and rationalism, which holds conclusions reached through pure reasoning from first principles above all others. This investigation seeks to explore how the empiricist and rationalist approaches each serve the pursuit and advancement of astronomy as a science. Using a thorough analysis of the existing literature on empiricism and rationalism in astronomy, as well as data from interviews of several practicing expert astronomers in and around the University of Colorado Boulder who take empiricist and rationalist approaches to astronomy research, this investigation finds that astronomy as a productive, growing field of research achieves its greatest successes when empiricists and rationalists can work in close proximity. Increased communication and collaboration between researchers of the two approaches, as well as a stronger understanding of the applications and implications of empiricist and rationalist thought, can help to maximize these advantages. Table of Contents
Introduction ...... 1 Purpose ...... 1 Definition of Terms...... 2 Investigative Methodology ...... 3 Basic Background ...... 4
History ...... 7 Copernican Revolution: Birth of Scientific Astronomy ...... 7 Philosophy...... 10
Modern Day Astronomy ...... 15 Interviews ...... 16 Trends from Interviews ...... 22
Conclusions ...... 26
References ...... 29
Special Thanks to Interviewees...... 30
Appendix 1: Interview Response Summaries ...... 31
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Introduction
Purpose
While scientific research is typically characterized as investigation into the nature of the world according to the scientific method, various incarnations of the scientific method have been used as tools for discovery and learning. Equipped with our senses, humanity has witnessed and recorded countless events and phenomena – yet observation is but one step of the process. Far more than our senses, the pursuit of science demands the use of our wits. In fact, parallel to the more commonly recognized school of empiricist science, which relies upon observation and experimentation to achieve results and draw conclusions, there is the school of rationalist science, governed only by reasoning and inferences made from prior knowledge. There is a longstanding debate in the philosophy of science regarding the merits and limitations of each.
Of all the sciences, it is astronomy that is affected most profoundly by this debate. The nature of astronomy, with a subject matter so broad, so large, and so distant that direct experimentation akin to studies of chemistry or medicine is in essence impossible in many cases, dictates that an empiricist pursuit of astronomy is highly limited. At the same time, the vast majority of accepted physical models of the universe in the last few centuries have assumed a universe governed by laws that apply as well to the largest and most distant galaxies as they do to ten-kilogram projectiles fired off the back of fifty-kilogram carts in high school physics textbooks. This homogeneity greatly eases and enhances the scope of the discoveries, or at the very least the reasonable inferences, that can be made via rationalist thought.
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This investigation examines the extent to which astronomy as a scientific pursuit benefits from a rationalist approach as compared to an empiricist one. These two schools of thought are not necessarily mutually exclusive, but instead may be codependent and often build on one another. This paper is concerned with that particular interaction between rationalism and empiricism, as both are used extensively to expand the current body of knowledge in astronomy.
In order to assess and compare the relative breadth and effectiveness of either approach, it is not sufficient to simply compare the results of each; it is instead necessary to examine their relative strengths and weaknesses, and apply those to the needs of astronomy today.
This investigation hypothesizes that while empiricism provides a necessary step in the advancement of astronomy by confirming rationalist theory and providing new questions to be explored, the bulk of new advancements in astronomy comes from the rationalist approach.
Definition of Terms
In order to present a coherent and meaningful discussion of the merits of rationalism and empiricism in the context of astronomy, certain critical terms require definition. For the purposes of this paper, these definitions are as follows:
Rationalism: Merriam-Webster defines rationalism as “a theory that reason is in itself a source
of knowledge superior to and independent of sense perceptions.” In the context of
astronomy, this denotes an approach to research that is built around known natural laws
and the basic principles of mathematics. In a purely inductive epistemology, the basic
principles of mathematics and a simple understanding of natural law are sufficient to
predict and describe all possible natural phenomena, independent of any observations. An
astronomer who practices rationalism is a rationalist.
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Empiricism: Again using the Merriam-Webster definition, empiricism is “the practice of relying
on observation and experiment especially in the natural sciences.” In contrast to
rationalism, empiricism holds observational data above inductive reasoning. Even if a
hypothesis is mathematically proven beyond doubt, a strict interpretation of empiricism
demands that conclusive observations be made. An astronomer who practices empiricism
is an empiricist.
Theory: A scientific theory is the generally accepted description or explanation of a natural
phenomenon. The theory of a phenomenon can predate or be more in-depth than its
observation. Theories in astronomy are typically heavily grounded in mathematics and
computer models, and as such are associated with the rationalist school of thought. A
theorist is an astronomer who manipulates and develops theory. Theorists are rationalists.
Observation: Observation is the practice of collecting data on a natural phenomenon, typically
for the purpose of better understanding it or similar phenomena. Observation can predate
theory, though this is rarer than the reverse since theory is not subject to the same strict
technological limits of observation. An astronomer who practices observation is an
observer or an observationalist. Observers are empiricists.
Investigative Methodology
This investigation focuses on the potential for growth in the current body of knowledge, and as such takes into account recent advances and trends such as gravitational wave observations and the ongoing explosion of exoplanet research. However, as the present does not exist in a vacuum, certain critical results of the recent and historical past of astronomy research
(primarily, the Copernican Revolution and the implications of 20th century space-time theories)
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are also considered. Initial and preliminary research examined the historical driving factors and limitations of astronomy research, again with a focus on the Copernican Revolution and 20th century space-time theories. This research was later supplemented by interviews of practicing expert astronomers, working actively in front-line research at nationally-recognized research centers. The interviews were designed to examine the nature of current cutting-edge astronomy research, with particular attention to what is being researched, how that research is being conducted, and which motivating factors drive current research. The interviews focus on the nature of the research as either empiricist or rationalist, but with particular interest in the specifics of the astronomers’ conscious relationship with both schools of thought as it is unlikely for any researcher to work entirely within one approach and have no experience with the other.
Basic Background
This investigation will consider to what extent the pursuit of astronomy as a science may be better suited for a rationalist approach, primarily concerned with reasoning, mathematical calculations and inferences from first principles, as opposed to an empiricist one, focused on experiment and observation. Preliminary research for this investigation utilized texts and essays on the nature of astronomy, primarily as this issue emerges in the history and nature of new discoveries in the field. Although the nature of astronomy as an investigative science is not always given the attention it deserves, the scientific and philosophical communities, and particularly the individuals whose expertise exists where the two approaches converge, have directed some attention towards that particular aspect of astronomy. In part, the relatively small degree of attention devoted to the topic is the result of segmentation and compartmentalization within the scientific and academic communities. The people responsible for collecting data and testing hypotheses within the scientific community are often not the same people who take the
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sum of observed astrophysical phenomena and attempt to describe them with the universal, monolithic expressions we call natural physical law. Consequently, the empiricist and rationalist sides of astronomy do not often seem to coincide, and there is little motivation to examine the suitability of each approach to advancing the science. Interestingly, it is during times when this compartmentalization is absent that some of the greatest advances in astronomy have occurred: as both an observational – that is, empiricist – astronomer under the instruction of Tycho Brahe, and an independent – rationalist – researcher and mathematician, Johannes Kepler derived his
Three Laws of Planetary Motion (Goldstein 1997) which, with greater refining from Sir Isaac
Newton (Harper 1997), remain to this day as some of the most useful tools in planning manned and unmanned space exploration, and the search for exoplanets – one of the newest and fastest growing fields of astrophysical science.
Perhaps as a direct result of the surprising success of Kepler and his contemporaries
(Goldstein 1997), the majority of the academic literature discussing the methods and philosophy of astronomy focuses on the work done during the Copernican Revolution and the birth of the post-renaissance, pre-industrial New Astronomy. Through a relatively small amount of observational data and comparatively primitive tools, Kepler and his contemporaries achieved a pace of advancement in astronomy not exceeded until Einsteinian relativity and Big Bang cosmogony, three hundred years later. However even today, a century after the birth of
Einstein’s cosmology, the methods and philosophy that facilitated perhaps the largest revolution in cosmological theory have not received the attention that their 17th century counterparts still enjoy. Perhaps this is because philosophers are reluctant to examine the mindsets that give rise to theories with such advanced notations and implications: Kepler and Galileo are taught to teenagers, while the intricacies of Einstein and Schwarzschild are reserved for highly specialized
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and advanced academic study. Even so, those with the greatest understanding of the theory (the astronomers themselves) do not often partake in the analytical examination of the nature of astronomy, as such an academic pursuit is seen as firmly within the purview of philosophical questions. In turn, philosophical questions do not typically attract the same kind of mathematical mind that is more common within the hard sciences like astronomy, so the analytical challenges are left to philosophers who may not have as solid a grounding in general astronomy knowledge, advanced mathematics, or the observational techniques used by astronomers. But if one is to describe how a theory came to be, it is prudent first to have at least a basic understanding of the theory itself. Therefore, the question receives less attention than it might otherwise if the fields of astronomy and philosophy were not so distinctly separate.
The body of literature on the nature of astronomy as an empirical and rationalist science raises several concerns that must be addressed where astronomy and philosophy intersect. In order to address the question of rationalism and empiricism as a means of expanding knowledge in astronomy, there must first be at least some discussion of the nature of scientific knowledge, as well as the degree to which either approach can be truly independent of the other. In recent years authors have pursued a greater insight into the practices and philosophies of more modern astronomers (Goldstein 1997). An investigation into these intersecting junctures may lead to valuable insights for the ongoing evolution of astronomy as a science in the present period when it is moving more and more to the forefront of the objectives and demands on the scientific community. Even so, there is a noticeable separation between those who practice astronomy and those who analyze the history, nature, and philosophy of the science.
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History
As with any science, the contemporary work in astronomy is the direct and indirect result of the precedents and body of knowledge established by a historical process. The science of astronomy is ancient, and the process that laid the groundwork for the modern practice stretches back millennia, to Ptolemy at the very least. However, the turning point for modern astronomy – the point at which the body of accepted knowledge begins to be recognizable to the research astronomer of today – is in the 17th century, at the birth of the Copernican Revolution. It must be acknowledged that the specific conclusions of Galileo and Kepler would be considered incomplete and vague by today’s standards. However, allowing for the observational and conceptual tools available in their time, and the consequent limitations on their efforts, the approach and methods used by the first heliocentricists represented one of the largest leaps forward in the history of astronomy as a science.
Copernican Revolution: Birth of Scientific Astronomy
The German astronomer Johannes Kepler is widely regarded as one of the most important and influential astronomers of all time. As a well-documented and fruitful era in the history of astronomy, Kepler and his contemporaries serve as an excellent introduction to the nature of astronomy, particularly in appreciating the relationships between observational techniques and mathematical reasoning. Professor Bernard Goldstein of the University of Pittsburgh, an expert in the history of science, provides this grounding in his 1997 essay “What’s New in Kepler’s
New Astronomy.” Goldstein lays out the meticulous methodology of Kepler’s research, explaining how the German astronomer progressed from hundreds of discrete data points to his three laws governing planetary motion. Kepler, Goldstein explains, did not start out seeking to
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upset two thousand years of what was then the dominant scientific understanding of the universe.
He only sought to reaffirm Copernicus’s work: first using similar a posteriori methods (that is, taking empirical data and discerning a pattern), and then using a priori reasoning – a rationalist approach, seeking to derive the same pattern using first principles of mathematics and geometry.
It was only when his rationalist, geometric model based on ellipses predicted the locations of planets in the sky far more accurately than perfect circles (which had been associated with the heavens since Ptolemy and before) that he realized there must be a flaw in the older models.
Goldstein takes particular care to say that Kepler did not make physical models of the paths of the planets, as many of his contemporaries continued to do even late into the 17th century. Even after Kepler had published his works, some astronomers failed to realize what Kepler had reasoned out: along with his contributions to the descriptions of the paths planets take around the sun, Kepler was one of the first astronomers to realize that planets do not orbit on shells or
“orbs” around the sun, but rather are pulled along their orbits by a physical force. He did incorrectly assume that the planets move through a significant fluid medium, but this assumption did not affect the accuracy of his geometric results. Several of Kepler’s incorrect assumptions, as well as the incompleteness of his expressions for planetary motion that prevented them from describing a universal law, were resolved in the late 17th century when Sir Isaac Newton refined
Kepler’s work with the benefit of calculus and his own three laws of mechanics.
While Kepler made his advances through a priori rationalist reasoning, Newton’s further contributions are owed to a posteriori empiricism. While Newton is primarily regarded as a physicist and mathematician, his contributions building on Kepler’s laws of planetary motion were a critical step forward in the advancement of astronomy, as his universal equations would later be used to describe phenomena at every scale of astronomical study. A strong counterpart to
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Goldstein’s description of Kepler comes from Professor William Harper, a philosopher at the
University of Western Ontario. In his 1997 essay “Isaac Newton on Empirical Success and
Scientific Method,” Harper gives an in-depth illustration of Newton’s methodology in his search for an expression of universal gravitation, and it becomes clear how the two scientists differ.
Where Kepler set out only to confirm the results of his predecessor using a separate, perhaps less fallible method, the goal of Newton’s search was always a universal law of gravitation. When
Newton’s derivations implied that the Moon’s orbit seemed to come from a gravitational force slightly weaker than the inverse square law he had already determined from the orbits of the planets, rather than adjust his calculations to correct for the more complicated Earth-Moon-Sun system he assumed that the (extremely small) discrepancy was the result of the Sun’s influence on the Moon. While this assumption turned out to be well-justified and correct, it illustrates the stark difference between a purely empiricist approach and a rationalist one. Harper is quick to add that along with Newton’s perhaps surprisingly less mathematically-grounded methodologies, the English physicist attempted to impose upon his own work a more demanding qualification of success: not only must a theory accurately and reliably predict phenomena, but the parameters of the theory must be accurately and completely described by the phenomenon it describes.
Perhaps this is why Newton’s work in astronomy came directly from observational data rather than the mathematical expressions for motion and force that he derived himself: by using only what the phenomena could tell him, Newton was able to avoid describing phenomena with unmeasurable parameters. Whatever his reasons, Newton’s empiricist approach refined Kepler’s expressions for planets within our solar system into a universal expression that, three hundred years later, would be used alongside Einstein’s relativity to plan missions exploring our solar system, and to predict the properties of planets detected around other stars.
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While the 17th century astronomers laid the groundwork and set the bar for future work in the field, theirs is not the ultimate determining influence on the state of astronomy in the 21st century. Instead, this honor is attributed to the numerous and momentous advances in astronomy made in the 20th century. Perhaps the single most revolutionizing of these advances, and the one that set into motion a resurgence of mathematical, scientific, research and philosophical issues for the science of astronomy would be Einstein’s Special and General Theories of Relativity, published in stages from 1907 to 1915. The scope and extent of the consequent re-examination of fundamental and established questions of physical laws, their mathematical proofs, and their complex philosophical underpinnings continues to this day, dramatically affecting both the scientific and philosophic fields of inquiry. Both science and philosophy, and in turn, research, are grappling with issues of space-time and motion relationships that lie at the very core of each of their bodies of knowledge. In the context of this essay, suffice here to say that the current fertile conceptual environment of debate, redefinition and conflicting theoretical projection occurring throughout the branches of physics, puts astronomy front center in the public eye and scholarly worlds in substantive ways that recall the Ancient Greeks. As Dr. Jennan Ismael of the
University of Arizona affirmed to the discomfort of some of the physicists, philosophers and researchers in attendance at the June 2016 Time in Cosmology conference at the Perimeter
Institute for Theoretical Physics in Waterloo, Canada, “This is a moment — and I know everybody here is going to hate this — but physics could do with some philosophy.”
Philosophy
With or without their conscious recognition, astronomers are both driven and held back by philosophical factors. While the empirical approach to astronomy is typically limited by the quality and quantity of observations that can be taken and recorded, the rationalist approach is
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primarily bounded by the limits of existing scientific knowledge. Though it may take time for scientific knowledge to grow to the point of encompassing certain natural laws, rationalism holds that the laws themselves had always been there. With enough a priori information – particularly the calculus and geometry pioneered by Newton, Leibniz, and their contemporaries – there is little reason Kepler could not have derived the universal expressions of gravitation and orbital energies himself. However, for this rationalist approach to astronomy to be truly effective, particularly where the laws that govern the evolution and birth of the cosmos are concerned, two things must be true: the laws of nature must be logically necessary, and the first principles of mathematical reasoning must be known. If there are multiple possible conclusions from the same set of correct fundamental axioms, it is impossible to deduce the correct conclusion through a priori reasoning alone. Similarly, the mathematical expressions that describe the universe cannot be derived without first knowing the laws of mathematics – this would be akin to winning a game of chess without knowing how the pieces move.
Professor George F. R. Ellis of the University of Cape Town tackles this predicament in his 2013 essay “Why Are the Laws of Nature and the Universe as They Are? What Underlies
Their Existence?”. He builds his essay around what he calls the three fundamental issues:
1. “Why do they [the mathematically expressed laws of nature] exist at all, and why do they have
the nature they have, leading to our physical and mental existence?
2. “Is the ultimate reason pure happenstance, probability, necessity, or purpose?
3. “What is the nature of their existence -- is it prescriptive or descriptive?”
(Ellis 2013)
While the first and third issues are fascinating in their own right, the answers to the questions they pose do not have a direct implication for the nature of the study of astronomy. The
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second issue, however, could severely limit the extent to which rationalist pursuits can assist in the advancement of astronomy. If natural law does not necessarily follow from mathematical law, there must be a limit to how much can be reasoned out independently of observational data.
Fortunately for the rationalist perspective, Ellis invokes a Platonic world of abstract realities
(philosophers might refer to these realities as Platonic Forms, abstract entities that represent the ideal forms of objects, of which tangible objects are simply shadows or poor imitations) in which the fundamental laws of nature might reside, independent of the physical reality. If this is the case, fundamental natural law would be unchanging and, in fact, necessary. Less fortunately for rationalism, Ellis adds a qualification: many, and perhaps all mathematical expressions we use to describe physical and astronomical phenomena, particularly our theories of gravity (as was shown in the beginning of the 20th century when Einstein’s macroscopic Theory of Relativistic
Space-Time displaced Newton’s Theory of Universal Gravitational Attraction, and again when
Relativity was found to be discontinuous with the equally powerful predictive tools of microscopic Quantum Mechanics), are emergent properties, not fundamental laws. Even if the fundamental laws exist in some ontologically pure sense, Ellis argues that we do not yet have access to them.
Even generously granting the assumption that the laws of nature do exist in an ontologically pure state, and even more generously granting that we, as conscious beings, do have at least the potential to access them as such, it can be argued that the purely rationalist approach is unreliable at best. Professor Frederick Suppe of the University of Maryland presents one such argument in his 1997 essay “Science Without Induction.” Suppe, a philosopher by training and career, describes an epistemology of science in which all scientific knowledge, from the newest raw data to the most well-supported theories of cosmology, is held as non-inductive –
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that is, while reasonable conclusions can be drawn from scientific research, at the broadest level no sound scientific claim necessarily entails any other sound scientific claim. Suppe’s argument is based not in the methodology or traditions of scientific research, but rather on the sociology and philosophy of the scientific community itself. Because scientists communicate in such vastly different ways (and, regrettably, with such vastly varying degrees of success) depending on whether they are addressing each other, their publishers, the media, or the public directly, Suppe argues that scientific knowledge as we are familiar with it is not necessarily a reliable inductive tool.
The problem is only compounded when we consider that scientific information may travel through tens if not hundreds of stopping points – each of which may alter the information, even unintentionally – before it reaches a consumer. In Suppe’s epistemology of science, rationalism (which depends wholly on the integrity of inductive reasoning from scientific principles, as rationalism holds induction to be the most valuable tool available to scientists) is essentially invalidated. If it is to be held as an acceptable and equal alternative to empiricism, the objections raised in Suppe’s argument, many of which are reminiscent of objections Plato raises against the communication of knowledge in the Meno, must be satisfied or otherwise resolved.
Some of these objections may be addressed by a more thorough description of empiricism. While observation is the critical feature that separates empiricist practice from rationalism, the empirical process does not start and end with a single observation. Empiricist science can involve just as much communication and collaboration among scientists as rationalist science, and arguments similar to Suppe’s can be made for limits on the human ability to interpret observations. In any case, we must acknowledge that the evolving theories provided by
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rationalist and empiricist approaches move continually towards a more complete answer, with each new theory improving significantly on its predecessor.
Whether or not the laws of nature exist as Platonic forms or in some other ontologically pure state, they must be both necessary and sufficient to define the past, present, and future state of the universe. In astronomy, the dominant framework for interpreting and describing the universe as a whole is space-time. Space-time theories have existed in some sense since Newton and Leibniz’s attempts to describe the universe as a physically consistent whole, but the most widely recognized use of space-time is Einstein’s adoption of the concept to explain the unusual asymptotic behavior of both space and time as various parameters increase. Professor John
Earman, a specialist in the History and Philosophy of Science at the University of Pittsburgh, discusses the implications of multiple classical and modern theories of space-time in his 1992 book World Enough and Space-Time. He divides these theories into two groups based on how they define space-time: absolutist theories like Newton’s, which have a defined and knowable
“origin point” and coordinate system; and relational theories like Leibniz’s and Einstein’s, in which particles only move in space and time relative to each other (and in the case of Einstein’s model, space itself does not have a rigid structure).
In some sense, this division is similar to the empiricist-rationalist split, as Newton preferred observational methods and therefore was more comfortable describing space-time with a defined system of coordinates (even though relational principles can be used to simplify his equations in some contexts). According to Earman, Newton held that with enough information it is possible to determine the alignment of an absolute space-time from the inside. Newton used a thought experiment of two rotating systems, each alone except for an observer within an absolute space-time, to justify this: first, a bucket of water spinning on its axis. Knowing the properties of
Quarles Empiricism and Rationalism in the Advancement of Astronomy 15
water, the speed of rotation can be found by observing how high the water is “pushed” up the edges of the bucket as it spins. Similarly, the direction of spin can be observed by applying a torque and observing how the water level at the edge of the bucket changes. In his second model, a pair of globes spin around each other, connected by a rope. The speed and direction of the spin can be found by observing the tension in the rope, again as a torque is applied to the system. In both cases, an observer spinning with the objects would perceive the system as remaining stationary with respect to itself, as rotating an object does not inherently alter its shape. These thought experiments are also strong examples of the empirical approach to problem solving: observations are made, and the data are used to construct a model that is mathematically consistent with existing knowledge. In the rationalist approach of Leibniz, Einstein, and many others, existing expressions are mathematically manipulated to give models that accurately describe the data. In relational models of space-time, this method is more successful as there is a danger that purely empiricist results could be contaminated by a difference in frames of reference: Kepler could not have solved the orbits of the planets as ellipses if he had kept the
Earth as a stationary center point, as pure empiricist reasoning from the apparent motion of stars and planets would (and did) dictate.
Modern Day Astronomy
While the discussion of the history and philosophy of astronomy provides a valuable context, this investigation seeks to examine the extent to which astronomy benefits from rationalism and empiricism today. In order to do this, current trends and research must be investigated.
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Interviews1
To create a more complete image of astronomy in the present day, seven practicing experts in various fields of astronomy were interviewed on their research and experience. Their areas of expertise included orbital dynamics of stars around supermassive black holes and of small bodies in the outer solar system, collisional and dynamical evolution of small bodies in the outer solar system, planet formation, Jovian planet and icy body atmospheres, terrestrial planet upper atmospheres, massive star formation, protoplanetary disks, the interstellar and intergalactic media, high-redshift cosmology, and the surfaces and interiors of small worlds in the outer solar system. Based on both self-identification and interpretation of their answers, three interviewees were theorists (practicing rationalists), and four were observers (practicing empiricists). The questions posed in the interviews were designed to investigate the nature of the interviewees’ research as either empiricist or rationalist, but with particular interest in their conscious relationships with either or both schools of thought. The goals and motivations of research were investigated, as well as methods and secondary approaches. Care was taken to formulate questions in an objective manner, giving equal validity to rationalist and empiricist thought to avoid creating a bias in the responses.
Two interviewees, Assistant Professors Dave Brain and Ann-Marie Madigan of CU
Boulder, are on the evaluating committee of this thesis and thus were more acutely aware than the other interviewees of the context for the questions during their interviews. Both were aware of individual questions before their interviews, but neither participated in the original formulation of those questions.
1 A full summary of all interview responses, sorted by question and then interviewee, can be found in Appendix 1, beginning on page 31.
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Question 1: Was there an event, discovery, or unanswered question that pulled your
attention towards the specific project or part of the field you work in today?
By looking at the factors that motivated the beginnings of astronomers’ careers, this question sought to find patterns in the inspiration for and execution of research. This question was not as closely related to the goal of this paper as the later questions, however it does serve a valuable purpose: the advances made in this generation will not only inspire the advances of future generations, they will inspire the people who make those advances. If a certain type of research inspires others to be theorists over observers, or vice versa, then that research plays a more important role in how research will be conducted in the future.
There was no expectation of a trend in the responses to Question 1. However, a clear trend did emerge. Foremost, all respondents did identify that their attention was pulled to the field by curiosity about current projects or unanswered questions. These respondents were inspired to fill perceived holes in the body of knowledge of astronomy. Of the seven respondents, five were primarily inspired by a discovery or unanswered question that had been
(or could be, in the case of unanswered questions) resolved with an approach that matched their preferred methods – that is, a theoretical approach for theorists, or an observational approach for observers. Only one theorist and one observer differed from this trend and were inspired by the opposite approach from the one they primarily rely on in their own research, however, both indicated a high level of experience with both theory and observation. This implies that astronomers may be inclined to conduct their research in a similar fashion to the research or questions that originally inspired them to become astronomers.
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Question 2: In your opinion, what is the single most important discovery in your field (as
recent or as far back as you want)? Why?
The purpose of this question was to determine how theorists and observers value theory and observation in relation to each other. While the expectation was a strong tend towards favoring the results of the more familiar approach, this question was also meant to catch discrepancies between the expectation and actual responses.
As expected, all observers considered an observational discovery to be the most important development in their field, and all but one theorist gave that honor to an advancement of theory. The one theorist who chose an observation chose the detection of the cosmic microwave background, a critical discovery that helped to strengthen Big Bang theory and spawned several other theories of cosmology and the evolution of the universe.
Question 3: When you have a new research question, what is your first step in
investigating? Where does that take you?
This question was originally designed to find trends in the practices of self-identified theorists and observers. The expected trend was consistent with strict interpretations of rationalism and empiricism, in that theorists would start similarly to each other (likely with back- of-the-envelope calculations or other examinations of basic principles as applied to the research in question), while observers would also have similar initial steps to each other (probably organized around close examination of the available data).
The responses did not exhibit this trend, or any similar trend. Two theorists and two observers started by examining the available data, a first step that was only expected of the observers. One theorist and one observer started by doing preliminary back-of-the-envelope
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calculations, which was only expected of theorists. The remaining interviewee, an observer, said that her first step was to look at the available project grants in the community, and to determine which of those, if any, were applicable to her research question. This brings up an interesting consideration: no matter how valuable a particular research question may be, the investigation has to be funded in order to take place at all. This can lead to compromises to fit a research proposal to a particular grant: it may be preferable to apply to a grant that funds many projects but is not exactly aligned with the original question, rather than to a grant that matches the question but will fund fewer of the proposed projects (Howett).
The lack of a trend in the responses to this question hints at a deeper phenomenon: while theorists and observers may not typically and actively use each other’s approaches, they are aware of and utilize the same basic methods of scientific investigation. In practice, rationalism and empiricism are not so strongly opposed as their implementations in theory.
Question 4: Have you ever encountered a problem in your research that couldn’t be
resolved with your usual methods? What was it? How did you solve it? (Did
you solve it?) With the advantage of hindsight, how would you approach it
differently?
Like Question 3, Question 4 was designed to find trends in the practices of self-identified theorists and observers. This question was focused on how the interviewees responded when their typical methods did not bear fruits. Though this question was, in part, designed to indicate whether theorists would turn to empiricist methods and observers to rationalist methods, no such trend was expected.
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No particular trend emerged, though the responses did provide more valuable insights.
The most common response, given in some form by three of the seven interviewees, was to seek out input from colleagues. All three interviewees who responded this way sought out assistance from experts in rationalist and empiricist approaches, and did not have a preference for researchers with a similar approach to their own. This again showed direct and practical interaction among between rationalists and empiricists, indicating that the two schools of thought are not strictly isolated, and that the process of research itself may require their interplay. The same two respondents who indicated that they started with back-of-the-envelope calculations
(one theorist and one observer) indicated that they again took a rationalist approach, double- checking their work with simplified and order-of-magnitude calculations to ensure that they did not make an error in assumptions or approach. One observer mentioned turning to other rationalist approaches, particularly computer-based models, for a clearer view of what the trends in the data should be, but that observer qualified that he did not consider models reliable enough to substitute for observing data and preferred to wait until more complete observations were available (Brain).
The remaining respondent, an observer, admitted that rather than trying to work around problems he encounters in his research, he often finds himself taking on the problem itself as the new focus of his research. The problem, he found, is often more interesting and more valuable than the question that created it in the first place (Spencer).
Question 5: Has your approach to new questions changed with experience?
While the main goal of this question was to see how the methods of empiricist and rationalist astronomers evolve within a single generation, this question also sought to see if any
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theorists had started as observers, or vice versa. Since neither rationalism or empiricism says anything about how one should adapt to new experience, and neither school of thought is more prone to conversion to the other, no specific trend in the responses was predicted. It was held as unlikely that any practicing researchers would make a full switch from rationalist to empiricist thought, or vice versa.
The responses showed no trend, and no respondents indicated a shift in their methodology great enough to be considered a credible transition from one school of thought to the other. The most common response was that experience begat a greater understanding of the basics, along with an accelerated progression in research even in the face of unexpected results.
Some respondents, notably the younger experts, indicated that with experience they became more willing to approach colleagues for assistance and input. This leads to the possible conclusion that more experience fosters a greater understanding and respect for the methods of the opposing school of thought, a conclusion further reinforced by one observer’s realization that he has grown more familiar with and trusting of mathematical models -- though, as in Question
4, he still prefers hard data to its simulated counterpart (Brain).
Question 6: Do you find that you rely more on observations and data, or models and
calculations? Why?
This was a clarification and self-identification question, designed to find discrepancies between overall practice, and the stated and implied approach to scientific problem solving. No discrepancies were expected; that is, it was expected that all empiricists would indicate a greater reliance on observations and hard data, while rationalists would be more concerned with models and mathematical calculations.
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All responses to Question 6 were consistent with responses to previous questions: as predicted, all empiricists focused in some manner on observation and data, and all rationalists preferred models and calculations. Two respondents (one theorist and one observer) claimed a reasonably equal reliance on both, but clarified that their results and conclusions from research typically relied on the methods more consistent with their preferred overall approaches.
Trends from Interviews
Ideally, the interviews would have included a greater number of experts, from a wider range of specialties and situated at various locations, perhaps even internationally. A future expansion of this study would include a similarly organized survey, as one-on-one interviews become impractical with large numbers of respondents. Despite the relatively small number of respondents interviewed for this iteration of the investigation, care was taken to include a range of specializations on the cutting edge of modern astronomy. However, there is still a potential bias from location, both geographically and considering the proximity to a large, publicly-funded research university and multiple publicly-funded research organizations. The relatively high concentration and availability of researchers and research funding created by the presence of the university and research groups is not necessarily typical, and may afford local astronomers more resources and more access to their colleagues than they might have in a less concentrated setting.
At the same time, the presence of this concentration made it more easily possible to contact and engage with a wider range of specialists in the area.
A further consideration regarding the premises and responses to the interview questions derives from the fact that the survey was conceived of and designed by someone with training in both astronomy and philosophy, with the implicit goal of investigating the intersection of the two
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fields. Among the other stated goals, part of the purpose of the interview was to elicit, indirectly, whether any philosophical premise underlaid the approaches to research of any of the interviewees. The respondents, however, were all answering as practicing researchers in the field of astronomy. Responses were more concerned with the results of research, and the applicability of those results, than with the particular philosophy driving the research. This reflects an important difference between the contemporary research climate for astronomy and the long- standing history, going back at least to Kepler and Galileo’s time: proportionally, astronomy research is far more expensive to conduct today than it was in the sixteenth century, and, proportionally to the number of people with access to higher education and training, there is less funding available to pursue said research (Galilei 1637). This echoes one of the more unusual but insightful responses from the survey: when asked what her first step after selecting a new research question, Dr. Howett responded that she seeks to find the most practical and reliable sources of research funding for the project. In a more competitive funding environment, astronomers must not only consider how valuable the potential results of their research could be, but also what opportunities for funding exist, and how likely their research proposal is to secure that funding. This factor did not come up elsewhere in the interviews, but it is important to consider as the trends in responses are investigated.
The clearest trend implied by these interviews is that there appears to be a greater level of communication, collaboration, and correspondence between practicing rationalists and practicing empiricists in astronomy than the existing literature would suggest. However, it is important to keep in mind the unusually high density of researchers in the area this survey sampled: on and within walking distance of the university campus, there are offices and research spaces for over five hundred professors, graduate students, and non-academic researchers studying various
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cutting-edge questions in astronomy. Communication and collaboration among researchers and across research disciplines is a natural consequence of this high concentration of specialists in this field. Three of the seven interviewees specifically indicated that, when they encounter a problem that they cannot solve via their regular methods, they seek out advice from colleagues in their field, whether those work differently from them or in the same way: rationalists and empiricists would seek out both. The free exchange of ideas between empiricists and rationalists means that the vast majority of projects are, at some point, seen from empiricists and rationalist perspectives. The benefit to this is twofold: the initial project will progress more swiftly and smoothly to a publishable result, thus increasing the productive output of the researchers involved in the project, and it will inspire further empiricist and rationalist research.
Interestingly, if one looks back on the history of the largest steps forward in astronomy, one finds this process of interchange between an observation-driven origin, a theoretical explanation, and later further substantiation of the new theory in new observation. This process has historically opened up at least as many questions as it has answered. From Brahe’s observational data on the motions of the planets, and their apparent inconsistency with the then- accepted Ptolemaic model, Kepler was able to derive a much more accurate theory of physical laws to predict the orbits of the planets. This he did almost concurrently with Galileo’s observations of the moons of Jupiter, which unbeknownst to either of the early modern astronomers would eventually be used to help prove the general case of Kepler’s laws. In the next century, Newton expanded the mathematical laws of motion and physics, using his own advancements in theoretical mathematics to solve a general case of Kepler’s laws that worked for all pairs of orbiting bodies – or rather most pairs of orbiting bodies, as it turned out that
Newton’s predictions for the orbit of Mercury matched the observations far less accurately than
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his predictions for the planets that orbited further from the Sun. This discrepancy was not fully corrected until Einstein’s theories of relativity, with space-time models that, when pushed to the limits of plausibility, produced unforeseen effects like time dilation, redshift, and thanks to
Schwarzschild’s mathematical work, gravitational singularities that could bend and trap light.
Through the course of the twentieth century, each of these phenomena was observed, and as more observations of black holes and other dense, massive objects began to provide a clearer picture of their behavior under relatively typical conditions, rationalists began to consider the behavior of massive objects under atypical conditions, like the seconds immediately before the collision of co-orbiting black holes. From such considerations the first iteration of a hypothesis of gravitational waves was formed, and after decades of attempts to detect gravitational waves
(with everything from piezoelectric sensors to laser interferometers), the first gravitational waves were detected in September of 2015. This is only one of many similar patterns in astronomy, and by decreasing the distance – both in space and time – between the empiricists and the rationalists, the rate that this pattern progresses has increased.
Whether a particular astronomer tends towards rationalist or empiricist methods in their research seems to be an accident of chance rather than a conscious decision. Personality, education, and exposure to the various results of different approaches to research all play a role in an aspect of professional and academic work that would benefit from a more deliberately interconnected process, even at the level of training. A more rigorous understanding of the relationship between rationalist and empiricist work, perhaps informed by a philosophical perspective and experience in both approaches to research, would facilitate astronomers in taking full advantage of the concentrated environment that naturally arises around large research institutions. This would allow the field as a whole to make the most of the resources it is already
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using. The work itself is already rigorously conducted in accordance with clearly-established methodologies, and a comparably systematic understanding of the advantages and limitations of theory and observation would certainly accelerate progress.
Conclusions
During the research and interview processes for this investigation, persistent evidence emerged that achievements in astronomy, historically and in the present period, involve a continuous and productive interplay between the empiricist and rationalist approaches of separate, individual astronomers. Whether we consider the way Kepler’s observations and
Newton’s calculations together made possible the Copernican Revolution, or how Einstein’s
Specific and General Theories of Relativity (which drew upon both empirical and theoretical predecessors) were substantiated and clarified through the essential rational and empirical contributions of Einstein’s contemporaries Karl Schwarzschild and Edwin Hubble – to name just a few – or anecdotally when contemporary researchers describe how they work through impasses in their research efforts, this pattern of interplay appears to be a necessary part of the advancement of the science. Neither approach on its own appears to be sufficient for rapid and sustainable progress in astronomy. It is always important to remember the limitations of theoretical knowledge, and to allow time for direct observation to confirm – or at least provide strong evidence for – any hypothesis before it is truly accepted as fact. However, as Sir Arthur
Stanley Eddington wittily advised his fellow astrophysicists and astronomers with a reverse dictum, “It is a good rule not to put overmuch confidence in the observational results that are put forward until they are confirmed by theory.”
At present there may appear to be a clear and distinct delineation between the specialties within astronomy that are populated more by empiricist or by rationalist researchers. Cosmology,
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cosmogony, and large population orbital dynamics tend towards rationalist approaches; while planetary science, solar physics, and stellar evolution attract mostly empiricist researchers.
However, this distribution is neither necessary nor constant through time. Rather, the distribution is contingent on the existing body of knowledge and the available techniques, technologies, and resources available to researchers at any given time. In the past, empiricism and rationalism have
“leapfrogged” to some degree: observations are made until something is found that theory cannot adequately explain, then theory is improved and refined until it begins to accurately predict the existing body of knowledge, as well as other, as-yet-unobserved phenomena. Observers then take to their instruments – often using improvements suggested by the implications of new theory – to confirm the theory’s predictions, and the cycle starts again. This cycle can be accelerated by continuing to promote large research institutions where hundreds of astronomers can work on different cutting-edge problems in close proximity, and by equipping astronomers with some degree of training in empiricist and rationalist techniques as well as an understanding of the implications and applications of both from a philosophical perspective.
Contrary to this investigation’s hypothesis, this conclusion indicates that it is not rationalism that independently provides the bulk of astronomy’s advancements, but rather it is the interplay between rationalism and empiricism that facilitates astronomy in moving forward.
Neither approach should be set aside or considered simply as a stepping stone for the other to use on its path to new breakthroughs, instead, the pattern of “leapfrogging” should be embraced by empiricist and rationalist researchers, in order to facilitate smoother transitions between each phase of the cycle.
Further, among the greatest astronomers, historically, there is a discernible tendency to wax philosophical after making the largest forward leaps in the science, possibly as an after-
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effect of glimpsing and elucidating something of the eternal. This suggests how essentially inseparable these two domains of study may be. Just as we can neatly differentiate astronomy from philosophy, we also can simultaneously recognize their inseverability throughout history.
We may do the same with the empiricist and the rationalist approaches utilized by the practitioners of the science: they differ fundamentally and at the same time are interdependent for scientific progress. Judging by the preliminary revelations of the interviews and research that led to this paper, this is an area deserving further and deeper investigation and analysis.
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References
Earman, John. World Enough and Space-Time: Absolute versus Relational Theories of Space and Time. MIT Press, 1992. Eddington, Arthur Stanley. New Pathways in Science. Macmillan, 1935. Ellis, George F. R.. ‘Why Are the Laws of Nature and the Universe as They Are? What Underlies Their Existence?’ The Causal Universe. Eds. George F. R. Ellis. Michael Heller, and Tadeusz Pabjan. Copernicus Center Press, 2013. 21-56. Falk, Dan. “A Debate Over the Physics of Time.” Quanta Magazine, Simons Foundation, 19 July 2016. Galilei, Galileo. Dialogues Concerning Two New Sciences. 1638. Translated from Latin and Italian by Alfonso De Salvio and Henry Crew, Macmillan, 1914. Goldstein, Bernard. ‘What’s New in Kepler’s New Astronomy’ The Cosmos of Science: Essays of Exploration. Eds. John Earman and John D. Norton. University of Pittsburgh Press, 1997. 3-23. Harper, William. ‘Isaac Newton on Empirical Success and Scientific Method’ The Cosmos of Science: Essays of Exploration. Eds. John Earman and John D. Norton. University of Pittsburgh Press, 1997. 55-86. Merriam Webster Online, Merriam Webster, n.d. Suppe, Frederick. ‘Science Without Induction’ The Cosmos of Science: Essays of Exploration. Eds. John Earman and John D. Norton. University of Pittsburgh Press, 1997. 386-429.
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Special Thanks to Interviewees:
Prof. Dave Brain, CU Boulder/LASP. 1 November 2017. Prof. J Michael Shull, CU Boulder/CASA. 9 November 2017. John Spencer, Ph.D., Southwest Research Institute (Boulder CO). 10 November 2017. Prof. Ann-Marie Madigan, CU Boulder/JILA. 10 November 2017. Howett, Carly, Ph.D., Southwest Research Institute (Boulder CO). 14 November 2017. Bill Bottke, Ph.D., Southwest Research Institute (Boulder CO). 28 November 2017. Prof. John Bally, CU Boulder/CASA. 29 November 2017.
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Appendix 1: Interview Response Summaries
Self-Identification: Would you consider yourself a theorist (rationalist) or an observationalist (empiricist)?
Answers:
Ann-Marie Madigan: Theorist! Have never taken observations.
Bill Bottke: Theorist. But the two must work together! Don’t let models get in the way of data. Observers can have a better understanding of the concepts. More data = better; leads to more opportunities
Carly Howett: Observer. Looking at real data over models.
Dave Brain: Observationalist
John Bally: Mostly an observer, but fascinated by theory. Interested in quantum gravity, started in cosmology.
Final comments: We now have access to many new windows: full EM spectrum, gravitational waves, and neutrinos. LOTS of new opportunities for observations! Science drives society, is fundamental to economy. Astronomy is at the forefront with new mysteries (dark matter, dark energy) - new technologies will lead to better science and better world.
J. Michael Shull: Started out a theorist. Have done work in observations, but stayed focused on theory.
John Spencer: Primarily an observer, some theory.
Self-Identification: What is your particular area of expertise?
Answers:
Ann-Marie Madigan: Dynamics -- started in galactic center (how stars around supermassive black holes interact with each other), including fundamental dynamics and gravitational waves. More recently into planetary systems, particularly in outer solar system. Same principles apply, same tools.
Bill Bottke: Planetary scientist: outer solar system evolution. Small bodies (asteroids, comets, KBOs), collisional and dynamical evolution, planet formation, evolution of small satellites. Bombardment, craters, understanding the solar system in terms of small bodies
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Carly Howett: Ph.D. in planetary atmospheres: interactions with infrared light. Started on Jovian planets, but moved to icy worlds after arriving at SWRI. Also work on instrument development. Observations, research, and instrumentation.
Dave Brain: Terrestrial planet upper atmospheres.
(Alternate Question): Why did you become an astronomer? Like the feeling of being an explorer - the first person to understand something new on an intellectual level. Astronomy has a lot of frontiers - it’s vast, lots of opportunities to understand how our own planet works. Planetary science is just turning knobs to different settings.
John Bally: Star formation, formation of star clusters and planetary systems from the interstellar medium. Trained as a mm radio astronomer, did work on cmbr and galactic star formation. IR provided better resolution, sword in visual wavelengths as well. More recently, observations of Orion proplyds (protoplanetary disks, ppds) use of long wavelengths - survey of galactic plane. Current interest: impact of massive star birth on interstellar environment.
J. Michael Shull: Broad range: interstellar and intergalactic matter, galaxies at high redshift, first stars and galaxies, supernovae, sn remnants. Mostly theoretical, some use of Hubble for imaging and spectroscopy.
John Spencer: Outer solar system satellites and small worlds. Space missions (New Horizons, Cassini), earth and space based telescopes. Planetary science.
Q1: Was there an event, discovery, or unanswered question that pulled your attention towards the specific project or part of the field you work in today?
Answers:
Ann-Marie Madigan: Separate science not taught in school until 16. Very quickly decided: wanted to do physics. Astronomy is the coolest part of physics, so of course gravitated towards it. Wasn’t sure of field of study until almost Ph.D., needed a research project but had nothing. Post-doc gave a short talk to group of scientists on how stellar remnants distribute around black holes. Latched on to topic, became specialty.
Bill Bottke: First inspiration: watched Apollo 11 and other moon landings, inspired but thought science would be more fun.
Carly Howett: “I’m inquisitive, I like answering questions, and I like working alone.” Sort of “fell into it:” looking at Ph.D.’s, planetary science had an interesting mix of hardware and software development. Stayed in planetary science because of the discovery of activity on Enceladus - “beautiful and intriguing.” Also: student involvement in research.
Dave Brain: President George Bush commissioned the “Ride Report:” what should the United States focus on in space? Humans on Mars. Mars is the most similar to Earth, life could
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have possibly developed there. Potential for new knowledge about Earth from studying Mars.
John Bally: Lack of understanding of star formation - knowledge focus on stellar interiors and stellar deaths, not much on births. Main source of stars (molecular clouds) only discovered in 1971 thanks to mm-range radio telescopes. Cold interstellar medium = best birthing place for stars. mm-range telescopes are different from optical: one pixel with a full spectrum instead of many monochrome pixels. Early research included 100,000-point map of Orion in mm wavelengths, high velocity CO detection in young star outflows,
J. Michael Shull: Really a physicist, by training. Started in particle physics and theory, took classes in astrophysics. Saw more applications, breadth appealed. Ph.D. thesis in astrophysics. Astrophysics as a conjoined application of astronomy and physics, using theory to figure out how the universe works.
John Spencer: New exciting missions! Voyagers in the Jupiter system. Broad approach: what’s out there, what can we learn about small bodies?
Q2: In your opinion, what is the single most important discovery in your particular field (as recent or as far back as you want)? Why?
Answers:
Ann-Marie Madigan: Heliocentric solar system? Understanding gravity (as a force [Newton] and then as the distortion of space-time [Einstein]), exoplanet discovery explosion.
Bill Bottke: The Nice Model. Started in 2005: solar system formed in a different, tighter configuration. Giant planet orbits become unstable, migrate to current location and disrupt outer solar system (creating Kuiper belt) -- affects every body in the solar system. Keeps answering major questions in ss formation; attempts to find problems just answer more questions instead.
Follow-up Question: Without the Nice Model, would it be possible to have our current understanding? Based on observation rather than theory?
Possible, but hard to say. Some exoplanet systems seem to have had major upheavals - something had to cause that. Nice Model came from Kuiper belt hypotheses, but could have come from exoplanet observations.
Carly Howett: Advancements of observation tools! Classical astronomers were limited by what kinds of glass they had access to, but now we have full-spectrum access and even non- light-based instruments! Much more to see!
Dave Brain: Two: 1, realization that Earth is not the center of the universe. 2, first discovery of an exoplanet. Both inform knowledge of our place in the universe. Earth is not fundamentally special; knowing that there are “other earths” reinforces that.
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John Bally: Bipolar outflows: jets from poles of forming stars leads to self-regulation of star formation; release of power and momentum disperses a typical cloud after 5-10% is converted into protostar. Also: cataclysmic explosions (supernova scales) from massive star formation (detected by ALMA, a ground-based millimeter space telescope with 10x resolution of Hubble) - Luminous Infrared Transients
J. Michael Shull: Cosmic Microwave Background Radiation: confirmation of Big Bang theory, confirms one hypothesis and facilitates several more. Birth of Precision Cosmology, high accuracy in study of the universe. In specific fields: solar neutrinos for stellar physics, black holes (binary x-ray sources, quasars) for x-ray astronomy.
Follow-up Question: Clarification on the increase in accuracy of the Hubble Constant since Hubble’s first derivations?
Better characterization of distance indicators: poor correction for dust extinction, development and improved definition of standard candles.
John Spencer: Realization that life is uncommon, at least in our solar system. No vegetation on Mars, no jungles on Venus. Places where life could exist, but no evidence of actual extraterrestrial life. Better appreciation for life on Earth, because it’s not common! Others: diversity of worlds in solar system. “We assumed that everything was as Earth- like as was consistent with the data.” Solar system is amazing and diverse, but not in ways that are hospitable to life.
Q3: When you have a new research question, what is your first step in investigating? Where does that take you?
Answers:
Ann-Marie Madigan: First, read EVERYTHING on the topic before doing original research. Looking for an interesting angle. Discover something in numerical simulations or calculations that looks weird or exciting. Research: figure out why! How does it work? How can it be tested in the real world?
Example: 3 years ago, was simulating disks of stars around massive black holes. Encountered challenging question, decided to tackle it head on instead of avoiding the problem. Question: does the average eccentricity of various stars affect the dynamics of the disk? Hypothesis: no significant effect. Observations: sudden change in behavior at 0.6 eccentricity! Wound up working on this discrepancy between expectations and observations exclusively for 2 years. New problem, very little literature. Lots of documentation on instabilities by Russian scientists, no documentation there.
Bill Bottke: As a grad student, listened to talks but rarely engaged in the content. Took notes to help focus attention. Wrote down interesting ideas and connections - has someone considered it before? Looks at work of other observers or modelers on relevant topics,
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sets up a team of relevant experts. Models are the end goal - start simple (proof of concept) then tweak it until it produces a sufficiently accurate physical model. Interacting with other scientists is paramount!
Carly Howett: The best projects are the ones that get funding. First, make sure a question is viable: is there data? Has someone done this before? How does this fit into open RFPs? Demonstrate that the idea will work (work around pitfalls) - takes a month or two to be sure. Also: getting invited to other people’s projects. Challenges: finding the right question for interesting data, finding the right data for interesting questions.
Dave Brain: Make a measurement, or look at someone else’s measurement. Observations are the go-to tool for science. Spacecraft are immensely valuable tools, but models can be useful as well.
John Bally: Rough estimate BOTE calculations, then full analytical calculations -> computer programs. Also look at feasibility: can the phenomenon even be observed? Also, look into hunches. Private telescopes are great, but if you don’t work for a corporate research institute, you can still budget an extra 10% observing time for hunch observations. Sometimes this leads to very interesting projects! New data! Example: expecting jets from ppds, found them - over 3pc in length! Pumping material and energy into interstellar medium.
J. Michael Shull: New objects: Fast Radio Bursts have dispersion (arrival time depends on wavelength) - implies that there is a plasma medium in the way. Look at other parts of specialty -> intergalactic medium. Does it make sense: calculations and theory can lead to a different answer.
John Spencer: Classical approach: ask question, design experiment, take observations, answer question with results. Practical, real world approach: get data, see questions presented by data, try to answer questions. Most important work is typically NOT the research originally planned in proposals. Best questions are the ones you don’t expect, so you can’t ask them in advance.
Q4: Have you ever encountered a problem in your research that couldn’t be resolved with your usual methods? What was it? How did you solve it? (Did you solve it?) With the advantage of hindsight, how would you approach it differently?
Answers:
Ann-Marie Madigan: See example above. 3d orbital dynamics much more complicated, harder to visualize what’s happening. Simplified system to essential parts. Change to approach: talk to lots of people about the problem. Nobody has the answer, but everyone has different questions. Talk more = learn faster.
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Bill Bottke: Insufficient proof on the paper? Talk to more people! Someone will have the information you need! More information makes the model stronger, but you might need to cross discipline boundaries - or just wait - to find it.
Carly Howett: One of the benefits of working at SWRI is access to other experts. Talking to others always helps! Someone knows the answer (or knows someone who knows). Conferences are even better.
Dave Brain: Encountered exactly this in Ph.D. thesis. Measurements of magnetic field and electrons, but no measurements of ions (field and electrons stay put, ions escape the atmosphere. Can’t count what you can’t measure…) Accustomed to working with incomplete picture; available data gives clues for guesses. Guesses have uncertainty, depending on how good and how complete the data is. Identify what would help fill the gaps and reduce uncertainty. Long-term solution (decades): send a spacecraft to look at the problem up close. Short term: look at models for better understanding - NOT fully accurate in value, only in trend.
Look at individual event (useful for finding anomalies) or overall trend (useful for finding patterns). Neither approach is complete on its own. Anomalies relative to statistics; statistics relative to anomalies
John Bally: BOTE, numbers, formulae. Must know constants and equations! Plug everything in and get BOTE estimates, check assumptions and see what’s right or wrong.
J. Michael Shull: First: check your math! Check your units! Check your assumptions! Do a sanity check: do a BOTE, or a try another approach.
John Spencer: If the problem is more interesting than the original research, might just drop the first and pursue the second instead. (“Partly because I’m not that disciplined.”) Published papers don’t have to be identical to proposed research, as long as there is similarity and acknowledgement of original goals.
Q5: Has your approach to new questions changed with experience?
Answers:
Ann-Marie Madigan: More knowledge and experience speeds up the process. Even when overwhelmed and confused, it is easier to see the necessary steps. More methodical, knowing how to tackle the problem. (“Boring, but true.”)
Bill Bottke: More experience = more connections, more knowledge, more doors to look through. Connections between fields lead to more connections. Problems: “old scientist disease”: getting stuck in old models, dismissing new before they’ve been disproven.
Carly Howett: Initial approach was “this helps, so it should be funded.” Recently, bigger focus on specific and powerful questions + proof-of-concept for ideas. Have all the necessary
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people on a proposal, but nobody you don’t absolutely need. The right sets of qualifications! Learn from rejections, don’t get defeated.
Follow-up Question: Do you think your approach would be different in an environment where you have more or less access to research funds?
Yes. Grant sizes are important, but even more important is funding rate: a tangential RFP with a 40% funding rate is better than a spot-on RFP with a 4% funding rate. It takes time to write a proposal; why waste time on something that probably won’t create results?
Dave Brain: More acceptance of the value of models. Right way and wrong way, but still a strong preference for observation data Models have uses that observations don’t (tweaking knobs to see what matters and how much), but needs observations to be grounded in reality.
John Bally: n/a
J. Michael Shull: Absolutely! Intuition, expertise, experience makes up for lack of stamina for long calculations. Going to colloquia and conferences is always useful, too. Experience: faster to know what you’re looking for. Less time spent poring over old journal articles. More work in teams - small teams are better! Some papers have over 100 authors (rare, but it happens -- Sloane DSS), but small groups are easier to work with.
John Spencer: Less jumping between projects - probably due to involvement with group projects (responsible for a specific role that others depend on). The field may be changing; harder to be sure that problems are completely new. Harder to get observing time without being attached to a specific goal.
Follow-up: Other astronomers I have talked to have mentioned preferring smaller groups. Do you agree?
“Small fish in a big pond” effect: more room to move, easier to change direction, faster reactions to new discoveries. Large groups have benefits too! Designing observations for New Horizons post-Pluto, to enable science for other observers.
Q6: Do you find that you rely more on observations and data, or models and calculations? Why?
Answers:
Ann-Marie Madigan: Both! Depends on the project. Often more theory. Example: intermediate- mass black holes in dynamical systems. Purely theoretical: there are supermassive and stellar-mass black holes, but no observed intermediates! Outer solar system projects are more driven by observation. Overall more of a theorist. Sufficient knowledge of theory leads to insight into biases and inaccuracies in observations. Observations still crucial, but interesting theory is sometimes more useful.
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Bill Bottke: As a modeler, better at manipulating computer code than numbers. Need constraints. “The most important question is what problem are you trying to solve?” - Hal Levinson. The data is already there, but how to explain it? Can’t tackle a problem without constraints from data. Models are best used to explain anomalous data.
Carly Howett: Both are used closely: models explain what we see in the data. Models drive perceptions of data, and data drives creation of models
Dave Brain: More on observations, models have uses. See answer to Q6
John Bally: n/a
J. Michael Shull: Both - they lead to two different kinds of papers. Theorists, observers, and experimentalists (usually everyone is at least two of the three). Focus on the theory, but observation data is useful for inspiration and confirmation. Simple models can be used to support observational conclusions.
John Spencer: Have done theoretical work, but direct observations are much more satisfying. Example: Temperature anomaly (10-15 degrees colder) on Mimas - what could cause this? Other observations to understand and explain the phenomenon; filling in the picture for others to model.