# Black holes and time dilation: how we could see interaction with other objects?

I have a question on the observable behavior of a Black Hole. So, I am not asking what is going on “now” at the Event Horizon or how can I “see” (get particles or waves). The question is how should it look like for a faraway observer.

Taking into account time dilation near the Black Hole the observer will see it as “always collapsing” to the Event Horizon, since time dilation at it will be close to stopping (intervals between events will be huge for external observer). So, for me (observer), the Black Hole should freeze, infinitely getting to existence (needed mass under the Event Horizon).

But if at the same time the Black Hole, let’s say moves through the cloud of other objects, let’s say gas, dust, planets or stars, it should affect them. But for me it is still faraway from them and “frozen”. How the Black Hole can be “frozen” and “almost moving”? Where it is for me – at the place where it is still forming in dilated time or here, near the star it is tearing apart?

If it moves in the “almost frozen” state, how should the interaction look like?

Am I correct in thinking that in this case time “dilated” near the Black Hole and time considered when it moves through space are “different ones” and the latter is not affected by dilatation?

(I saw many similar questions, but they consider slightly different question - namely, the falling of the object to the Black Hole, which is different, since consider only "dilated" time. My question about interaction with the large-scale world.)

• Imagine a smartphone showing a video in a slow motion. If you throw the smartphone away, it will fly fast while still showing the video in a slow motion. What happens at or in the smartphone is different from what happens to the smartphone as a whole. Sep 1, 2021 at 18:57
• @safesphere, it would if the smartphone (Black Hole) didn't affect time around it. So the question is more "how this frozen affected space-time interacts with alive surrounding space-time". In your example, the cell phone should stay in my hand, since time is stopped around it. Sep 1, 2021 at 19:19
• Yes, because your hand is close to the phone. Now consider the phone is on a long selfie stick. When you throw it, the stick will fly wth the phone, the phone will keep showing a video in a super slow motion, but will fly very fast with no problem. Sep 1, 2021 at 19:47
• @safesphere, great example with the stick, it makes even easier for me to explain the question. Two moments: (1) When the phone "stops" time, I will move stick around me and the part of the stick in my hand should move while the part of the stick near the phone should "hang" since it is frozen in time; first question here is how will the stick look after that while one end moves (maybe two rounds around me) and other one hangs? (2) if time hands for phone, how this will coexist if I trust by this stick some other object? The end of the stick doesn't seem to move, but it should in reality. Sep 1, 2021 at 21:20
• "the part of the stick near the phone should 'hang' since it is frozen in time" - It is frozen relative to the phone, not relative to you. So when you push, the phone will fly away from you with the stick "glued" to the phone by the effect called "linear frame dragging" (same "freezing" as what you are asking about). All this of course is over simplified to give an illustration of the idea that things near the horizon are "frozen" relative to the horizon, but they are free to move together with the horizon relative to you or relative to any remote object. Sep 1, 2021 at 23:01