I Theoretically, can perfectly flat spacetime exist in the Universe?

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Perfectly flat spacetime cannot exist in the presence of mass and energy, as general relativity states that these factors cause spacetime curvature. Theoretically, a perfectly spherical shell of matter can create a flat region of spacetime inside, but this requires specific conditions and does not apply to the surrounding area. Achieving absolute flatness is impossible due to the Heisenberg Uncertainty Principle and the inherent limitations of physical matter. Discussions also highlight that while gravitational waves can interact with matter, no materials can effectively shield against them, making the concept of perfect flatness practically unattainable. Ultimately, while flat regions can be approximated, true flat spacetime remains a theoretical ideal rather than a physical reality.
  • #31
Alien101 said:
Perfect flatness would require absolutely nothing in the entire universe
This is not correct. As already discussed in this thread, a spherical shell of matter in an otherwise empty universe has flat spacetime in the cavity inside.

You still can't have perfectly flat spacetime in the real universe, but your claim misses a case.
 
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  • #32
This thread is now closed since the OP question has been well addressed.
 

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