Zhiyong Deng I think it is important to put quantum theory in the right context. Quantum theory is a statistical theory which uses mathematical models to correctly and accurately predict the outcome of experiments. It does not give an insight into the true nature of matter.

This is why there have been so many difficulties with trying to provide a physical interpretation of the QM mathematical models. Once we accept this understanding of the scope of quantum theory we can stop worrying about the measurement problem, cats being alive and dead, Dirac’s sea, virtual particles, many worlds etc. etc.

Instead it is better to go back to first principles to explain the fundamental nature of matter and unify the fundamental forces.

This approach does not lead to the quantisation of Spacetime. Instead it explains the quantisation of the electron and light in continuous Spacetime. Here is an example of how this approach is applied to the hydrogen atom:

Preprint The Hydrogen Bond (June 2022)

Richard

In Special Relativity, space time is defined by relativistic invariant. In Periodic Relativty space time is defined by periodic invariant and quantum invariant.

Periodic relativity: basic framework of the theory.

General Relativity and Gravitation, Vol.42, No.6,

pp.1345-1374, (June, 2010).

http://dx.doi.org/10.1007/s10714-009-0908-5

https://www.researchgate.net/publication/225712819_Periodic_relativity_basic_framework_of_the_theory?ev=prf_pub

I am a philosopher on this question. I lean toward Carlo Rovelli.

As Hay says space and time as two distinct ontic things may be XOR XNOR oscillations "to draw distinctions".

But as Whitehead said long ago, with respect to the special theory of relativity, the key concept is the absolute interval, in other words, spacetime interval relative to participant observers.

With respect to gravity and the general theory of relativity, I find Rovelli mostly convincing: Gravity is geometrically granular and spacetime. In current view of the universe we currently live in, I suggest that spacetime itself is accelerating expansion that may be viewed as constantly pulling itself apart in all directions.

Funniest joke

Article Earth Gravity is not Newtonian

“Does space and time exist outside of matter?”

- to answer to this question it is necessary before to understand – what are “space”, “time”, and “matter” , more correctly “Matter”?, what is possible only in framework of the 2007 Shevchenko-Tokarevsky’s “The Information as Absolute” conception, recent version of the basic paper see

https://www.researchgate.net/publication/363645560_The_Information_as_Absolute_-_2022_ed

- and concretely in this case in the Shevchenko-Tokarevsky’s informational physical model

https://www.researchgate.net/publication/354418793_The_Informational_Conception_and_the_Base_of_Physics, where really fundamental phenomena/notions above are rigorously scientifically defined.

Brief answer is : all, space , time, and Matte absolutely fundamentally really exist, and coexist simultaneously. Matter fundamentally can exist only in its specific spacetime, i.e. in the fundamentally absolute, fundamentally flat, and fundamentally “Cartesian”, [5]4D spacetime with metrics (cτ,X,Y,Z,ct), where Matter is absolutely obligatorily is placed, it fundamentally cannot exist outside.

Cheers