According to our current understanding of physics, there is no universally agreed-upon notion of "now" that applies simultaneously across the entire universe. This concept is known as simultaneity. The theory of relativity, specifically special relativity and its treatment of spacetime, provides insights into this issue.
In special relativity, the concept of simultaneity depends on the observer's reference frame. Different observers moving relative to each other or situated in different gravitational fields will have their own perspectives of "now." This means that events that appear simultaneous to one observer may not be simultaneous to another.
Additionally, the speed of light plays a fundamental role in relativity. Information and signals can only travel at or below the speed of light, limiting how quickly we can receive information from distant parts of the universe. Since the universe is vast, and light from distant objects takes time to reach us, observing events "now" in remote regions of the universe is not possible in practice.
Therefore, there is no universal "freeze frame" that captures the entire universe in a single moment. Our ability to observe events in the universe is constrained by the finite speed of light and the limitations of our observational technology.