Open Physics
"Physics is an attempt conceptually to grasp reality as something that is considered to be independent of its being observed. In this sense one speaks of physical reality." Albert Einstein
Physics Open Educational Resources
Bookboon.com contains free eBooks and textbooks that can be downloaded as a pdf, no registration needed.
InTech publishes more than 2,300 open textbooks and 6 journals in a variety of subjects that fall under the heading of science, technology, and medicine.
MIT OpenCourseWare (OCW) is a web-based publication of virtually all MIT course content. OCW is open and available to the world and is a permanent MIT activity.
Hippocampus offers educators a wide variety of multimedia content online, including videos, animations, and simulations. An additional feature offers educators the ability to create "playlists" for their students, which correlate specifically to their particular instruction material.
The AAPT ComPADRE Digital Library is a network of free online resource collections supporting faculty, students, and teachers in Physics and Astronomy Education.
Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations. PhET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.
Explore Nano Science/Technology
https://www.ncbi.nlm.nih.gov/search/all/?term=Nanoscience%20and%20Nanotechnology
http://www.jurn.org/#gsc.tab=0&gsc.q=introduction%20to%20nano%20science%20&gsc.sort=
https://www.semanticscholar.org/search?q=introduction%20to%20nano%20science&sort=relevance
Additionally
Several open textbooks on a variety of physics topics.
Explore courses, textbooks, homework exercises and ancillary materials. Topics include: Optics TextMaps, Quantum Mechanics, and Relativity.
Lumen Learning provides a textbook on Physics with various chapters such as Two-Dimensional Kinematics, Magnetism, and Geometric Optics.
MERLOT is a curated collection of free and open online teaching, learning, and faculty development services contributed and used by an international education community.
Milne Library Publishing at SUNY Geneseo manages and maintains Milne Open Textbooks, a catalog of open textbooks authored and peer-reviewed by SUNY faculty and staff.
This is a great resource that provides textbooks on various topics on astronomy, astrophysics, and space exploration.
Both a collection of open access publications and a publishing platform with a focus on social sciences and humanities.
OER Commons provides a curated collection of physics and astronomy resources and textbooks.
Published by Rice University's OpenStax, these free College Physics textbooks can be read online, in PDF, or on an iPad.