Someone told me that spacetime is a matter. I know that matter must be a mass or energy. Is spacetime a matter (mass or energy) , and if it is a mass. why can't we see it? Is it due to the presence of dark matter? If it is an energy. what is its source? The sun?? If it is not mass or...
I thought about this question for a long period of time. why time is elastic? I thought that if time is elastic ,so it must be able to deform. My imagination told me that deformation of time is represented by time dilation. If time can dilate (deform) ,so it must be elastic. In case you...