Philosophy of Physics: Spacetime
What is space? Is it something that exists in its own right (as an object, or substance)? Or does it consist in a network of relations between material objects? What is time? Does it exist? Does it have a direction, and does it "flow"? Is time travel possible? What does modern physics tell us about the nature of space and time?
This NASA/ESA Hubble Space Telescope image shows Messier 96, a spiral galaxy just over 35 million light-years away in the constellation of Leo (The Lion)
Image credit: ESA/Hubble & NASA and the LEGUS Team, Acknowledgement: R. Gendler Text credit: European Space Agency