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It does not exist in the real world but [[relativists]] still don't know why Einstein called it ''"the biggest blunder of my life"''. Just know that he did.

It does not exist in the real world but [[relativists]] still don't know why Einstein called it ''"the biggest blunder of my life"''. Just know that he did.

Couldn't figure it out why though<ref>Misner, Thorne, and Wheeler, 1973, ''"Gravitation"'', page 410.</ref>. They use it as "[[dark energy]]", not having slightest idea what it might be. And sending astronomers on wild goose chase to find it somewhere in the universe,

Couldn't figure it out why though<ref>Misner, Thorne, and Wheeler, 1973, ''"Gravitation"'', page 410.</ref>. They use it as "[[dark energy]]", not having slightest idea what it might be.

===Symmetric metric tensor of 4D spacetime===

===Symmetric metric tensor of 4D spacetime===