What happens to the final image of a person falling into a black hole?

  • Context: High School 
  • Thread starter Thread starter jBase
  • Start date Start date
  • Tags Tags
    Image
Click For Summary
SUMMARY

The final image of a person falling into a black hole appears to slow down and freeze at the event horizon due to the effects of spacetime stretching, which alters the perception of time for distant observers. This 'frozen' image does not remain visible indefinitely; rather, it fades as the redshifted light waves from the person reach the observer. The source of this image is not the person themselves, but rather the light emitted during their fall, which is always a reflection of past events. Ultimately, the black hole redshifts light infinitely, making the last observable emissions long wave radio signals.

PREREQUISITES
  • Understanding of black hole physics and event horizons
  • Familiarity with concepts of spacetime and redshift
  • Basic knowledge of light propagation and photon emission
  • Awareness of the implications of time dilation in relativity
NEXT STEPS
  • Research the effects of gravitational redshift on light near black holes
  • Study the concept of the event horizon in general relativity
  • Explore the relationship between spacetime curvature and time perception
  • Learn about the emission of long wave radio signals from astronomical objects
USEFUL FOR

Astronomy enthusiasts, physicists, and anyone interested in the implications of black hole physics and the nature of light in extreme gravitational fields.

jBase
Messages
3
Reaction score
0
Apparently, when viewed from a distance, the motions of a person approaching the event horizon of a black hole will appear to first slow down and then come to a complete stop as they pass through the horizon. Then, as I'm led to believe by what I've seen and read, that final 'frozen' image of the person remains forevermore, motionless and stuck at/on the horizon.

The 'slowing down' phase makes sense if I think about the observed motion of the person's fall as being divided into consecutive instants of time (or information) and each instant being recorded on the individual frames of a film strip. Without the black hole, the movie camera projects the film strip at a frame rate such that any motion appears fluid and 'normal', but with the black hole present, the stretching out of spacetime outside the horizon is equivalent to slowing down the frame rate, thus giving the appearance of slow-motion. Eventually, at the horizon, the camera stops at the final frame, and all motion has ceased.

What I don't get is how that final frozen image remains visible to observers long after the person has actually gone through the event horizon boundary! What is the source of that continuous image if nothing is there anymore? Wouldn't this make the black hole some kind of photo album or montage displaying a snapshot of everything that has ever fallen into it? Surely that would make the invisible black hole visible.

I'm quite sure I've misunderstood this concept, or the film strip analogy is flawed (probably both), so I'd appreciate any info or guidance on how to visualise this process without invoking any maths.

One further question: Using the same film strip analogy, would the observed fall into the black hole transition from smooth, fluid motion into jumpy, discrete steps of motion as the stretching of spacetime at the atomic scale decompresses the atomic-fluctuation information (in terms of photons) and makes it observable on our macroscopic scale? I guess this comes down to a question on the photon emission process.

Thanks
 
Physics news on Phys.org
jBase said:
What I don't get is how that final frozen image remains visible to observers long after the person has actually gone through the event horizon boundary! What is the source of that continuous image if nothing is there anymore?

Hi. Welcome to PF. The image doesn't remain visible forever. It fades away until you can no longer see it. The source of the image are redshifted lightwaves that are just reaching your eyes.
 
jBase said:
What is the source of that continuous image if nothing is there anymore?
The source of an image is never "what is there" it is always "what was there". You are always looking looking at light from events on your past light cone. Many of the stars you see at night you still see even though nothing is there anymore.

The black hole just redshifts the light infinitely.
 
Last edited:
I guess that the last detectable thing which could be observed of an object falling into a black hole would be a long wave radio emission.
 
Ok, that's a little clearer...Thanks for your replies.
 

Similar threads

  • · Replies 51 ·
2
Replies
51
Views
5K
  • · Replies 22 ·
Replies
22
Views
906
  • · Replies 40 ·
2
Replies
40
Views
3K
  • · Replies 67 ·
3
Replies
67
Views
6K
  • · Replies 73 ·
3
Replies
73
Views
2K
  • · Replies 43 ·
2
Replies
43
Views
4K
  • · Replies 31 ·
2
Replies
31
Views
2K
  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 35 ·
2
Replies
35
Views
4K
  • · Replies 11 ·
Replies
11
Views
3K