Newton on Space

Absolute space, of its own nature without reference to anything external, always remains homogenous and immovable. Relative space is any movable measure or dimension of this absolute space; such a measure or dimension is determined by our senses from the situation of the space with respect to bodies and is popularly used for immovable space, as in the case of space under the earth or in the air or in the heavens, where the dimension is determined from the situation of the space with respect to the earth. Absolute and relative space are the same in species and in magnitude, but they do not always remain the same numerically. For example, if the earth moves, the space of our air, which in a relative sense and with respect to the earth always remains the same, will now be one part of the absolute space into which the air passes, now another part of it, and thus will be changing continually in an absolute sense.

Absolute, relative? Which one do we ‘measure’?

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3 thoughts on “Newton on Space

  1. Previously I had replied to and forgotten to click on post comment, what I believe was Newton’s ideas about space to which you have just previously referred. Newton of Einstein But I have just scanned down a little and not found these statements of Newton about space. However, I believe I now remember from the long past that I was taught Newton’s physics was just a special case of Einstein’s physics which applied to small particles of matter which Newton’s did not and could not. But as the matter involved became larger Einstein’s physics transitioned into Newton’s physics. So Newton was not wrong as some seemed to consider or the Einstein’s physics did not refute Newton’s physics as some considered. But with regards to my actual understanding of these issues, the proceeding are just words.

    • Now I discover that your post was about Newton’s idea of space and not Einsteins as I suffered under the illusion that it was Einsteins.
      “For example, if the earth moves, the space of our air, which in a relative sense and with respect to the earth always remains the same, will now be one part of the absolute space into which the air passes, now another part of it, and thus will be changing continually in an absolute sense.” My previous comments about this, which I did not post yesterday, went something like this.

      I ordinarily never paid much attention to such statements as this, because like some you posts, I have no idea what is being stated. But now I give it shot to describe what this statement could mean to me. Newton explained the semi-diurnal tides observed at many locations, but not all. I can imagine it appeared easy to explain a semi-diurnal tide when the sun and moon were opposite each at the time of the full moon. However, the same reasoning could not be used at the time of the new moon. Newton’s explanation is simple to understand once it is stated for the case of the new moon during which it might seem there should only be a diurnal tide. The water toward the sun and moon is pulled more strongly than the planetary body is and the planetary body is pulled more strongly toward the sun and moon that is the water opposite the sun and moon are. Hence, because of the different accelerated motions of the three bodies, bulges of the water, relative to the planetary body, are created toward the sun and moon and opposite these heavenly bodies. And even though the gravitational influence of the sum is greater than that of the moon because the difference of their masses, the difference between the distance of the moon and sun are such that the differences in the ‘pull’ upon the water nearest, the earth, and the water furtherest by the two heavenly bodies gives the moon the greater influence. Simple once it is explained but not simple until it is explained.

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