People are saying that The Pillars Of Creation have been destroyed, and will take 400-500 Million light years to reach us. Can someone explain how do we know it when the light hasn’t reached us?

Question

People are saying that The Pillars Of Creation have been destroyed, and will take 400-500 Million light years to reach us. Can someone explain how do we know it when the light hasn’t reached us?

In: 1444

Answer 1

We don’t know it. It’s partly why the commonly repeated phrase “…the light from this thing has travelled millions of years to reach us” is problematic. There is no cosmic clock. All information travels at the speed of light. So for all intents and purposes, the pillars of creation are still there until we don’t see them anymore. In fact their gravitational effect on us is also just now reaching us.

Another example. If the sun disappeared “right now” we would continue to orbit it. And see it, and sunbathe in it. 8 minutes later the lights would go out. But what does it mean to say that happened in the past? what past? It happens IMO when the light and gravity change reaches you.

of course if someone discovers FTL travel then i’m wrong.