The concept of a universe refers to the entirety of space, time, matter, and energy that exists. So, if we imagine a scenario where there is no universe at all, it becomes challenging to conceptualize what would be left.
The absence of a universe implies the absence of space, time, matter, and energy as we understand them. It would mean that there would be no galaxies, stars, planets, or any other celestial bodies. There would be no physical laws or constants governing the behavior of matter and energy.
In such a scenario, it is difficult to speculate about what might exist or what conditions would prevail. Our current scientific understanding is based on observations and measurements within the framework of our universe. Without the universe, the very foundations of our knowledge and understanding would cease to exist.
It is important to note that discussing what might exist outside or beyond the universe is purely speculative, as our scientific knowledge is limited to studying and understanding phenomena within the universe itself. Speculations about the nature of existence without a universe often fall into the realm of philosophy or metaphysics, where various theories and ideas exist but lack empirical validation.