This book is a journey through the world of physics and cosmology, and an exploration of our role in this universe. We will address questions such as: What if the force of gravity were a little stronger? What if there were more of fewer atoms in our universe? What if Newton and not Einstein had been right? Would we still be here? Can the universe exist without us to observe it? Can chance explain the world around us, as well as us?

The purpose of this book is to phrase these questions and pursue the consequences of potential answers through rigorous scientific reasoning; in the process we will learn how the very small and the very large are interconnected, and even how we can affect events that happened six billion years ago.

Licensed CC-BY-4.0 with attribution instructions on page 2 of the document.

Table of Contents

Introduction 7
The fundamental forces 10
The force of gravity 18
What if … the force of gravity were different? 23
The electric and magnetic forces 26
The electric force 27
What if … the electric force were different? 39
The magnetic force 48
What if … the magnetic force were different? 58
The strong and weak forces 59
What if … ? 65
How do forces work? 74
The history of the universe 85
What if … ? 94
The history of our species 106
Odds 124
The building blocks of the universe 128
What if … ? 140
Dark energy 150
What if … dark matter were more interesting? 159
When you do not look…. 162
Manifestations of the wave nature of matter 169
The delayed choice experiment: Affecting the past 186
What if … ? 191
The story so far 195
Unification and our role 199
Fine-tuning? 214
The Multiverse and aliens 226
The laws of physics 234
The Anthropic Principle and Puddle Theory 237
Post mortem 249
Further reading and chapter notes 251

The Massachusetts Institute of Technology (MIT) OpenCourseWare (OCW) is a free and open educational resource for faculty, students, and self-learners around the world. OCW is a publication of MIT course materials both from the undergraduate and graduate levels. It does not require any registration, is not a degree-granting or certificate-granting activity, and does not provide access to MIT faculty. The course sites often contain lecture notes, problem sets, readings, assignments, exams, study materials, and other resources. Open courseware is available on a variety of subjects, including Earth, atmospheric, and planetary sciences, and can be used for self-study or curriculum development.

Applications of physics (Newtonian, statistical, and quantum mechanics) to fundamental processes that occur in celestial objects. Includes main-sequence stars, collapsed stars (white dwarfs, neutron stars, and black holes), pulsars, supernovae, the interstellar medium, galaxies, and as time permits, active galaxies, quasars, and cosmology. Observational data discussed. No prior knowledge of astronomy is required.

Discussion of the redesign of AST 1002 Descriptive Astronomy using a mashup of OER resources. Many of these tools could be replicated in other disciplines.

The slideshows that go with OpenStax Astronomy are PowerPoint, which is great for editing and improving, but a bit awkward for instructors who need to load MS PowerPoint in order to present. I used the cc-by license to place them on Wikiversity.

I also invite others to collaborate on developing OpenStax materials on Wikiversity and/or Miraheze.

Textbook for ASTRON 102 THE SOLAR SYSTEM at College of the Canyons
Surveys the solar system, including the earth and its motions and seasons; the moon, eclipses, and tides; the content and dynamics of the solar system; planets and their satellites, asteroids, comets, and meteorites; and the evolution of the solar system.

Walking up and down the hallways of Davey Lab at Penn State, you can find astronomers searching for and characterizing exoplanets, monitoring supernovae and other exploding stars, and measuring the details of the accelerating expansion of the Universe to determine the nature of dark energy. In Astro 801, we learn that with only the ability to measure the light from these distant, unreachable objects, we can still determine how the Solar System, stars, galaxies, and the Universe formed and evolved since the Big Bang. We are all citizens of the Universe, and in fact, you are made of starstuff. Come learn where the atoms in your body came from, and what will happen to them long after we are gone.

"2010 marks the 400th anniversary of Galileo's astonishing sightings of features on the moon, stars, and moons around Jupiter that no one had seen before. Recreate these new ways of seeing and exploring from the materials and techniques Galileo had on hand, while you reflect on the times and works of Galileo. What was it like to improvise new ways of seeing and exploring from the materials and techniques on hand? What do we notice? What surprises us? How can we relate to past experience and ideas? What are we curious to research? How does our experimenting grow into our learning? Let your own curiosity drive your explorations."

Global Satellite Navigation Systems (GNSS), such as GPS, have revolutionized positioning and navigation. Currently, four such systems are operational or under development. They are the American GPS, the Russian Glonass, the European Galileo, and the Chinese Beidou-Compass. This course will address: (1) the technical principles of Global Navigation Satellite Systems (GNSS), (2) the methods to improve the accuracy of standard positioning services down to the millimeter accuracy level and the integrity of the systems, and (3) the various applications for positioning, navigation, geomatics, earth sciences, atmospheric research and space missions. The course will first address the space segment, user and control segment, signal structure, satellite and receiver clocks, timing, computation of satellite positions, broadcast and precise ephemeris. It will also cover propagation error sources such as atmospheric effects and multipath. The second part of the course covers autonomous positioning for car navigation, aviation, and location based services (LBS). This part includes the integrity of GNSS systems provided for instance by Space Based Augmentation Systems (e.g. WAAS, EGNOS) and Receiver Autonomous Integrity Monitoring (RAIM). It will also cover parameter estimation in dynamic systems: recursive least-squares estimation, Kalman filter (time update, measurement update), innovation, linearization and Extended Kalman filter. The third part of the course covers precise relative GPS positioning with two or more receivers, static and kinematic, for high-precision applications. Permanent GPS networks and the International GNSS Service (IGS) will be discussed as well. In the last part of the course there will be two tracks (students only need to do one): (1) geomatics track: RTK services, LBS, surveying and mapping, civil engineering applications (2) space track: space based GNSS for navigation, control and guidance of space missions, formation flying, attitude determination The final lecture will be on (scientific) applications of GNSS.

This is an introduction to the study of the solar system with emphasis on the latest spacecraft results. The subject covers basic principles rather than detailed mathematical and physical models. Topics include: an overview of the solar system, planetary orbits, rings, planetary formation, meteorites, asteroids, comets, planetary surfaces and cratering, planetary interiors, planetary atmospheres, and life in the solar system.

The emergence of Western science: the systematization of natural knowledge in the ancient world, the transmission of the classical legacy to the Latin West, and the revolt from classical thought during the scientific revolution. Examines scientific concepts in light of their cultural and historical contexts.