is it just something imaginary or does it really curve? and since there's no directions in space then how does the space-time curve? not up nor down, how?
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Space itself doesn't emit or reflect electromagnetism (light) and our eyes need light in order to see. Space does really curve along with time. The effects of curving space can be seen in gravitational lensing of light and accurately predicts gravitational effects (is concurrent with Newtonian predictions and refines Newtonian predictions).
There is direction in space, it's called ;forward and back; side to side; up and down, it just depends on the reference frame.
There is direction in space, it's called ;forward and back; side to side; up and down, it just depends on the reference frame.
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What is it that we would see? We can not see space at all, whether curved or flat.
Additionally, photons, which we can see, carry no history. If a photon comes from direction x it is assumed that the emitter was in direction x.
However, we can keep a history of the emitters. If the position of a star is observed at midnight zenith and then again when it is milliarc-seconds away form the limb of the Sun it is farther from the Sun than expected. This is an expected effect of gravitationally curved space. There are other effects of gravitational lensing that we observe. Most commonly, multiple images of the same quasar, and galaxies smeared into arcs as if seen through a piece of wavy glass. Is this what is meant by seeing curved space?
And there certainly are directions in space. Just not absolute ones. To explain to someone the shape of a curved space one needs to establish an arbitrary, common reference of a zero point, a scale and three directions. Over my head, behind me, to my left; all are as meaningful in space as they are on Earth.
Furthermore, your "up and down" are arbitrary. Anyone more that a few dozen miles from you will have a different "up and down". Are there no directions outside of the town you live in either?
Additionally, photons, which we can see, carry no history. If a photon comes from direction x it is assumed that the emitter was in direction x.
However, we can keep a history of the emitters. If the position of a star is observed at midnight zenith and then again when it is milliarc-seconds away form the limb of the Sun it is farther from the Sun than expected. This is an expected effect of gravitationally curved space. There are other effects of gravitational lensing that we observe. Most commonly, multiple images of the same quasar, and galaxies smeared into arcs as if seen through a piece of wavy glass. Is this what is meant by seeing curved space?
And there certainly are directions in space. Just not absolute ones. To explain to someone the shape of a curved space one needs to establish an arbitrary, common reference of a zero point, a scale and three directions. Over my head, behind me, to my left; all are as meaningful in space as they are on Earth.
Furthermore, your "up and down" are arbitrary. Anyone more that a few dozen miles from you will have a different "up and down". Are there no directions outside of the town you live in either?