Yes I know it is a question that had troubled philosophers since ancient times. The answer to this question has been remarkably similar among most cultures. Plato felt it is not possible to tell dreams from reality. Ancient Indian sages said reality is not what you see or experience. Those are the workings of Maya, a camouflage created by god to make us feel live.
When you outgrow these misconceptions you realise that there is no reality. Not in the sense in which you asked the question anyway.
Quantum physics or the physics of the minute goes rather along this path. Here, particles appear in many places at the same time, a phenomenon which is described in most ancient texts. Although this description is not at the quantum level.
Time flies as it likes. I have tried to explain this in my few novels, but the red idea is tough to accept. I mean suppose I move myself a bit in time regardless of the speed of time. If we are talking and I pull this trick I will just vanish although I would still be right next to you in space.
This sleight of time travel has been described about Jesus, Krishna. I am certain that the ancients who wrote these scenarios had no idea what was going on. Yet they knew it had happened.
Any sufficiently advanced technology is indistinguishable from magic. That Arthur C Clarke. That was also the thesis of the Avadhuth. These phenomena are not in the so called quantum scale. But do we know what we are talking about when we call some effects quantum and others relativistic.
The only difference is in size. Suppose a Type V civilisation exists. I doubt that the people there would have a physical corpus. They would fill their space and overlap each other. There will no longer be any individuals. Tat Twan Asi.
I cannot believe that people will have separate existence in such a vastly superior world. In this situation universes would also overlap. You won’t have to look for a space time warp. You are yourself warped into the fabric of the minuscule and imponderably large.
Why do we say something is large, say a galaxy or even universe. That is because it requires a lot of time for you to travel from one end to the other. is Time itself is traversable then size becomes irrelevant.
I know this sounds silly. But wait for what is coming.