According to our current understanding of physics, there is no universally agreed-upon notion of "now" that applies simultaneously to the entire universe. This is due to a fundamental concept called "relativity of simultaneity" in Einstein's theory of relativity.
In special relativity, simultaneity is relative to the observer's frame of reference. Different observers moving relative to each other will disagree on what events are happening "now" at different locations in space. This is because the concept of "now" depends on the synchronization of clocks in a specific reference frame.
In general relativity, which describes gravity and the curvature of spacetime, the situation becomes even more complex. Gravitational fields can influence the flow of time, causing it to be experienced differently in different regions of spacetime. This means that even if observers could somehow synchronize their clocks across the entire universe, the effects of gravity would still cause their experiences of "now" to differ.
Furthermore, the universe is vast, and information cannot travel faster than the speed of light. Therefore, even if we were to attempt to take a "freeze frame" of the entire universe, the information from distant regions would take time to reach us. This means that what we observe is always a snapshot of the universe's past, rather than its instantaneous state.
In summary, due to the principles of relativity and the limitations of information propagation, there is no universally agreed-upon "now" across the entire universe. The concept of simultaneous events is relative to the observer's frame of reference, and the vastness of the universe coupled with the finite speed of light prevents us from having a real-time, instantaneous understanding of events occurring in distant regions.