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Jakz

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- Physical meaning of null spacetime interval

Hi all,

I've been trying to wrap my mind around the physical meaning of null spacetime intervals. I understand the metric of Minkowski geometry. And I understand that photons have no proper time and no reference frame: the spacetime interval between the emission and absorption of a photon is zero. They are the same event.

My question is: What does this mean? Is the fabric of spacetime warped to infinity by every photon passing through it? If I look up at Polaris at night, from my reference frame it appears to be 433 light years away in space, and 433 years away in time. But in spacetime, the emission of that photon and its absorption by my eye are the same event. Is this accommodated by a weird spacetime topology in which the worldlines of massive particles that are light-years apart in space intersect in spacetime for the exchange of energy? With "light" just being the way the interaction looks in our 3-dimensional perspective? Or am I off-track here? Thanks for any pointers you all can provide.

I've been trying to wrap my mind around the physical meaning of null spacetime intervals. I understand the metric of Minkowski geometry. And I understand that photons have no proper time and no reference frame: the spacetime interval between the emission and absorption of a photon is zero. They are the same event.

My question is: What does this mean? Is the fabric of spacetime warped to infinity by every photon passing through it? If I look up at Polaris at night, from my reference frame it appears to be 433 light years away in space, and 433 years away in time. But in spacetime, the emission of that photon and its absorption by my eye are the same event. Is this accommodated by a weird spacetime topology in which the worldlines of massive particles that are light-years apart in space intersect in spacetime for the exchange of energy? With "light" just being the way the interaction looks in our 3-dimensional perspective? Or am I off-track here? Thanks for any pointers you all can provide.