ABSTRACT The recent "explosion" in the number of extrasolar planets, or exoplan... more ABSTRACT The recent "explosion" in the number of extrasolar planets, or exoplanets, is perhaps the most exciting phenomenon in all of science. Two decades ago, no planets were known beyond the Solar System, and now there are more than 770 confirmed exoplanets and several thousand more candidates, while the mass detection limit has marched steadily downwards from Jupiter mass in 1995 to Neptune mass in the early 2000s to Earth mass now. The vast majority of these exoplanets are detected indirectly, by their gravitational influence on the parent star or the partial eclipse they cause when they periodically pass in front of it. Doppler detection of the planet's reflex motion yields a period and an estimate of the mass, while transits or eclipses yield the size. Exoplanet detection taxes the best observatories in space, yet useful contributions can be made by amateur astronomers armed with 6-inch telescopes. The early discoveries were surprising; no one predicted "hot Jupiters" or the wild diversity of exoplanet properties that has been seen. It is still unclear if the Solar System is "typical" or not, but at current detection limits at least 10 % of Sun-like stars harbor planets and architectures similar to the Solar System are now being found. Over a hundred multiple planet systems are known and the data are consistent with every star in the Milky Way having at least one planet, with an implication of millions of habitable, Earth-like planets, and of which could harbor life. Doppler and transit data can be combined to give average density, and additional methods are beginning to give diagnostics of atmospheric composition. When this work can be extended to rocky and low mass exoplanets, and the imprint of biology on a global atmosphere can be measured, this might be the way that life beyond Earth is finally detected for the first time.
Cosmology presents intriguing issues for the understanding and tracking of time. The big bang the... more Cosmology presents intriguing issues for the understanding and tracking of time. The big bang theory says that the universe began 13.8 billion years ago, in a situation of almost unimaginable temperature and density. The age of the universe is highly constrained by the world model, as long as there are reliable measurements of the current expansion rate (the Hubble constant), and amounts of baryonic matter, dark matter, and dark energy. A crucial cross-check on the model age comes from stellar chronometers and the ages of the oldest stars in the Milky Way. Landmarks in cosmic evolution reach back to about 380,000 years (recombination), 40,000 years (matter domination), and a few minutes (light element creation) after the big bang.
Astronomy is the oldest science, with connections to development of the most important concepts i... more Astronomy is the oldest science, with connections to development of the most important concepts in physics. A course is described that covers its evolution from prehistory to modern cosmology, giving due weight to the philosophical implications of the subject. The pedagogy is designed to let students develop their writing and reasoning skills. The newly developed course has been delivered to three distinct audiences: non-science majors at a major public university, adult community members taking the course for enrichment, and a worldwide audience of lifelong adult learners who enroll in a massive open online course (MOOC). Class content is informed by the scholarly literature on philosophy and the history of physics and astronomy. Subject matter is divided into thirteen chronological topics: Ancient Skies, Greek Science, Revolutions, Telescopes, Gravity, Evolution, Mapping, Relativity, Quantum Theory, Stars and Atoms, Galaxies, the Big Bang, and Life in the Universe. The topics are presented at a rate of one per week during the standard university semester, and they are parsed into five two-hour sessions for the local community audience and seven weeks of self-paced video lectures for the online MOOC audience.
Personal endings carry the most emotional weight, but our growing awareness of the universe has a... more Personal endings carry the most emotional weight, but our growing awareness of the universe has acquainted us with a spectrum of endings on different cosmic scales. First, there is the occasional intrusion of large pieces of debris from the solar system, which can be triggered by the approach of a nearby star. Then, there is the disruption to life and the biosphere caused by stellar death and cataclysm. Finally, there are endings that play out on the largest backdrop of space and time, such as the gradual dimming of the Milky Way as the lowest mass stars expire and the removal of galaxies from view and the possible disruption of space-time caused by dark energy. The Copernican awareness of cosmic evolution helps to put our own modest endings in perspective.
Higher education has an enormous potential to provide economic opportunities and career advanceme... more Higher education has an enormous potential to provide economic opportunities and career advancement for people in developing countries. Technology and the Internet can help reach the billion people who will be looking for affordable access to college instruction in the next few decades. Two promising strategies for serving this population are a for-credit version of a massive open online classes (or MOOC), and a microcampus where American universities partner with universities in the developing world to offer dual degree programs. Although MOOCs started as free courses for lifelong adult learners the mechanisms now exist for them to offer transferrable college credit. The microcampus mechanism offers highly scalable college education using a flipped classroom model. Both ideas hold out the promise of helping to democratize higher education and spread its economic benefits more widely.
ABSTRACT Personal endings carry the most emotional weight, but our growing awareness of the unive... more ABSTRACT Personal endings carry the most emotional weight, but our growing awareness of the universe has acquainted us with a spectrum of endings on different cosmic scales. First, there is the occasional intrusion of large pieces of debris from the solar system, which can be triggered by the approach of a nearby star. Then, there is the disruption to life and the biosphere caused by stellar death and cataclysm. Finally, there are endings that play out on the largest backdrop of space and time, such as the gradual dimming of the Milky Way as the lowest mass stars expire and the removal of galaxies from view and the possible disruption of space-time caused by dark energy. The Copernican awareness of cosmic evolution helps to put our own modest endings in perspective.
Video is an excellent vehicle for astronomy education and outreach. Usage patterns and user demog... more Video is an excellent vehicle for astronomy education and outreach. Usage patterns and user demographics are presented for short videos covering a variety of astronomy topics, delivered to public audiences from three websites, three YouTube channels, and three massive open online classes, or MOOCs. The data spans over a decade in some cases. The modality of the content ranges from short lecture presentations of sub-topics in astronomy to longer scripted pieces created by students to Q&A sessions held by the MOOC instructor with live audiences of 100-200. In the aggregate, the videos have attracted 1.2 million views, and those viewers have watched 77,300 hours of astronomy content. Most of the viewers are not based in the United States. Viewership rose dramatically at the outset of the COVID-19 pandemic and has not yet returned to pre-pandemic levels. The videos watched by lifelong learners taking a MOOC show a decline in usage as they progress through the online course. But on these...
We have compiled a large sample (N rv 600) of low redshift (z S; 0.3) Lya absorbers from HST arch... more We have compiled a large sample (N rv 600) of low redshift (z S; 0.3) Lya absorbers from HST archival data taken with the FOS (GI30H) and GHRS (GI40L) spectrographs. Comprised of 60 QSO sight lines, this dataset samples roughly 50 Gpc (tlz rv 10) of the local Lya forest. The resulting statistics are a dramatic improvement on what has been previously available for moderate column densities and compliment work being carried out with high resolution, narrow path length spectra that are sensitive to much lower column densities. We find that dN / dz = 35.16 ± 2.27 for a limiting equivalent width of 0.24 A, and dN 2 /dzdw exceeds an exponential distribution for w < 0.3 A. While preliminary results reveal no evidence of clustering, this large sample allows us to address line strength in future investigations. Additionally, low-redshift evolution, cosmic variance, and void statistics will be considered.
The Formal Darwinism project probes the connections between the dynamics of natural selection and... more The Formal Darwinism project probes the connections between the dynamics of natural selection and the design of organisms. Here, I explain why this work should be of interest to philosophers, arguing that it is the natural development in a long-running scholarly enquiry into the meaning of life. I then review some of my own work which has applied the tools of Formal Darwinism to address issues concerning the units of adaptation in social evolution, leading to a deeper understanding of the adaptation of individual organisms. Finally, I sketch some directions Formal Darwinism to explore beyond the biological sciences, with a focus upon cosmology.
StellarScape is an immersive multimedia performance synthesizing music, science, visual art, and ... more StellarScape is an immersive multimedia performance synthesizing music, science, visual art, and technology. The performance includes live musicians, sensors, electronic music, and dance, collaborating through interactive cinematography. The result combines kinesthetic and acoustic sensing with astrophysical simulations of star formation, in real time. This convergence research collaboration is catalyzed by the union of concepts at the confluence of astronomy, humanity, artistic expression through music and dance, and socio-technical experience. This paper summarizes the motivation for the project, the interdisciplinary collaboration required to execute it, goals for the audience experience, early results of the first performances, and ways the piece can be delivered in the future for entertainment, outreach, and education.
ABSTRACT The recent &quot;explosion&quot; in the number of extrasolar planets, or exoplan... more ABSTRACT The recent &quot;explosion&quot; in the number of extrasolar planets, or exoplanets, is perhaps the most exciting phenomenon in all of science. Two decades ago, no planets were known beyond the Solar System, and now there are more than 770 confirmed exoplanets and several thousand more candidates, while the mass detection limit has marched steadily downwards from Jupiter mass in 1995 to Neptune mass in the early 2000s to Earth mass now. The vast majority of these exoplanets are detected indirectly, by their gravitational influence on the parent star or the partial eclipse they cause when they periodically pass in front of it. Doppler detection of the planet&#39;s reflex motion yields a period and an estimate of the mass, while transits or eclipses yield the size. Exoplanet detection taxes the best observatories in space, yet useful contributions can be made by amateur astronomers armed with 6-inch telescopes. The early discoveries were surprising; no one predicted &quot;hot Jupiters&quot; or the wild diversity of exoplanet properties that has been seen. It is still unclear if the Solar System is &quot;typical&quot; or not, but at current detection limits at least 10 % of Sun-like stars harbor planets and architectures similar to the Solar System are now being found. Over a hundred multiple planet systems are known and the data are consistent with every star in the Milky Way having at least one planet, with an implication of millions of habitable, Earth-like planets, and of which could harbor life. Doppler and transit data can be combined to give average density, and additional methods are beginning to give diagnostics of atmospheric composition. When this work can be extended to rocky and low mass exoplanets, and the imprint of biology on a global atmosphere can be measured, this might be the way that life beyond Earth is finally detected for the first time.
Cosmology presents intriguing issues for the understanding and tracking of time. The big bang the... more Cosmology presents intriguing issues for the understanding and tracking of time. The big bang theory says that the universe began 13.8 billion years ago, in a situation of almost unimaginable temperature and density. The age of the universe is highly constrained by the world model, as long as there are reliable measurements of the current expansion rate (the Hubble constant), and amounts of baryonic matter, dark matter, and dark energy. A crucial cross-check on the model age comes from stellar chronometers and the ages of the oldest stars in the Milky Way. Landmarks in cosmic evolution reach back to about 380,000 years (recombination), 40,000 years (matter domination), and a few minutes (light element creation) after the big bang.
Astronomy is the oldest science, with connections to development of the most important concepts i... more Astronomy is the oldest science, with connections to development of the most important concepts in physics. A course is described that covers its evolution from prehistory to modern cosmology, giving due weight to the philosophical implications of the subject. The pedagogy is designed to let students develop their writing and reasoning skills. The newly developed course has been delivered to three distinct audiences: non-science majors at a major public university, adult community members taking the course for enrichment, and a worldwide audience of lifelong adult learners who enroll in a massive open online course (MOOC). Class content is informed by the scholarly literature on philosophy and the history of physics and astronomy. Subject matter is divided into thirteen chronological topics: Ancient Skies, Greek Science, Revolutions, Telescopes, Gravity, Evolution, Mapping, Relativity, Quantum Theory, Stars and Atoms, Galaxies, the Big Bang, and Life in the Universe. The topics are presented at a rate of one per week during the standard university semester, and they are parsed into five two-hour sessions for the local community audience and seven weeks of self-paced video lectures for the online MOOC audience.
Personal endings carry the most emotional weight, but our growing awareness of the universe has a... more Personal endings carry the most emotional weight, but our growing awareness of the universe has acquainted us with a spectrum of endings on different cosmic scales. First, there is the occasional intrusion of large pieces of debris from the solar system, which can be triggered by the approach of a nearby star. Then, there is the disruption to life and the biosphere caused by stellar death and cataclysm. Finally, there are endings that play out on the largest backdrop of space and time, such as the gradual dimming of the Milky Way as the lowest mass stars expire and the removal of galaxies from view and the possible disruption of space-time caused by dark energy. The Copernican awareness of cosmic evolution helps to put our own modest endings in perspective.
Higher education has an enormous potential to provide economic opportunities and career advanceme... more Higher education has an enormous potential to provide economic opportunities and career advancement for people in developing countries. Technology and the Internet can help reach the billion people who will be looking for affordable access to college instruction in the next few decades. Two promising strategies for serving this population are a for-credit version of a massive open online classes (or MOOC), and a microcampus where American universities partner with universities in the developing world to offer dual degree programs. Although MOOCs started as free courses for lifelong adult learners the mechanisms now exist for them to offer transferrable college credit. The microcampus mechanism offers highly scalable college education using a flipped classroom model. Both ideas hold out the promise of helping to democratize higher education and spread its economic benefits more widely.
ABSTRACT Personal endings carry the most emotional weight, but our growing awareness of the unive... more ABSTRACT Personal endings carry the most emotional weight, but our growing awareness of the universe has acquainted us with a spectrum of endings on different cosmic scales. First, there is the occasional intrusion of large pieces of debris from the solar system, which can be triggered by the approach of a nearby star. Then, there is the disruption to life and the biosphere caused by stellar death and cataclysm. Finally, there are endings that play out on the largest backdrop of space and time, such as the gradual dimming of the Milky Way as the lowest mass stars expire and the removal of galaxies from view and the possible disruption of space-time caused by dark energy. The Copernican awareness of cosmic evolution helps to put our own modest endings in perspective.
Video is an excellent vehicle for astronomy education and outreach. Usage patterns and user demog... more Video is an excellent vehicle for astronomy education and outreach. Usage patterns and user demographics are presented for short videos covering a variety of astronomy topics, delivered to public audiences from three websites, three YouTube channels, and three massive open online classes, or MOOCs. The data spans over a decade in some cases. The modality of the content ranges from short lecture presentations of sub-topics in astronomy to longer scripted pieces created by students to Q&A sessions held by the MOOC instructor with live audiences of 100-200. In the aggregate, the videos have attracted 1.2 million views, and those viewers have watched 77,300 hours of astronomy content. Most of the viewers are not based in the United States. Viewership rose dramatically at the outset of the COVID-19 pandemic and has not yet returned to pre-pandemic levels. The videos watched by lifelong learners taking a MOOC show a decline in usage as they progress through the online course. But on these...
We have compiled a large sample (N rv 600) of low redshift (z S; 0.3) Lya absorbers from HST arch... more We have compiled a large sample (N rv 600) of low redshift (z S; 0.3) Lya absorbers from HST archival data taken with the FOS (GI30H) and GHRS (GI40L) spectrographs. Comprised of 60 QSO sight lines, this dataset samples roughly 50 Gpc (tlz rv 10) of the local Lya forest. The resulting statistics are a dramatic improvement on what has been previously available for moderate column densities and compliment work being carried out with high resolution, narrow path length spectra that are sensitive to much lower column densities. We find that dN / dz = 35.16 ± 2.27 for a limiting equivalent width of 0.24 A, and dN 2 /dzdw exceeds an exponential distribution for w < 0.3 A. While preliminary results reveal no evidence of clustering, this large sample allows us to address line strength in future investigations. Additionally, low-redshift evolution, cosmic variance, and void statistics will be considered.
The Formal Darwinism project probes the connections between the dynamics of natural selection and... more The Formal Darwinism project probes the connections between the dynamics of natural selection and the design of organisms. Here, I explain why this work should be of interest to philosophers, arguing that it is the natural development in a long-running scholarly enquiry into the meaning of life. I then review some of my own work which has applied the tools of Formal Darwinism to address issues concerning the units of adaptation in social evolution, leading to a deeper understanding of the adaptation of individual organisms. Finally, I sketch some directions Formal Darwinism to explore beyond the biological sciences, with a focus upon cosmology.
StellarScape is an immersive multimedia performance synthesizing music, science, visual art, and ... more StellarScape is an immersive multimedia performance synthesizing music, science, visual art, and technology. The performance includes live musicians, sensors, electronic music, and dance, collaborating through interactive cinematography. The result combines kinesthetic and acoustic sensing with astrophysical simulations of star formation, in real time. This convergence research collaboration is catalyzed by the union of concepts at the confluence of astronomy, humanity, artistic expression through music and dance, and socio-technical experience. This paper summarizes the motivation for the project, the interdisciplinary collaboration required to execute it, goals for the audience experience, early results of the first performances, and ways the piece can be delivered in the future for entertainment, outreach, and education.
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Papers by Chris D. Impey