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Physical reality
We are faced with distinguishing the actual condition from the appearances. This is difficult, to say the least.
Albert Einstein had an interesting comment about the hidden reality we do not perceive directly without technical and imaginative assistance.
Light travels at 300,000 meters per second.
At that speed, you can deduce that the outer space that you see on a starry night is quite large, indeed.
Take for example when you look at the night sky. First realize the sun's light take 8 minutes to reach the Earth's surface; that is how far away the sun -- our start is from the Earth. Looking at the evening sky at the stars and the galaxies that stretch before you, you are really looking into the past. Light traveling from distant parts of the universe to our Milky Way Galaxy and our star cluster takes millions of years to traverse space. light also is affected by massive objects that warp space, life our sun, and force light to bend around the gravitationally strong obstacle, like water sliding around a rock.
a depiction:
A light ray bends as it passes a dense object.
Orion Nebula, as seen from the Hubble Space telescope
Physical is from the Greek root --physis-- the word for material existence. It conveys the ideas of form and function of the objects, conditions, and things we see, feel, touch, smell, taste, measure or otherwise observe around us.
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