Can a falling feather inside a rocket ship create a black hole?

  • Context: Graduate 
  • Thread starter Thread starter Ray Eston Smith Jr
  • Start date Start date
  • Tags Tags
    Black hole Form Hole
Click For Summary
SUMMARY

The discussion centers on the theoretical implications of dropping a feather inside a rocket ship that partially resides within a Schwarzschild radius. Participants debate whether the addition of mass from the feather could create a black hole and the observable consequences of such an event. Key points include the misunderstanding of black hole definitions, the effects of time dilation, and the potential for tidal forces to impact the ship. The conversation highlights the complexities of event horizon formation and the conditions necessary for a black hole to exist.

PREREQUISITES
  • Understanding of Schwarzschild radius and black hole physics
  • Familiarity with concepts of time dilation in general relativity
  • Knowledge of tidal forces and their effects on objects near a black hole
  • Basic principles of mass-energy equivalence as described by Einstein's theory
NEXT STEPS
  • Research the properties and definitions of black holes, focusing on Schwarzschild solutions
  • Study the effects of time dilation near event horizons in general relativity
  • Examine tidal forces and their implications for objects near black holes
  • Explore the concept of event horizons and their formation in astrophysical contexts
USEFUL FOR

Astronomy enthusiasts, physicists, and students of general relativity who are interested in black hole formation and the effects of gravity on mass and time.

Ray Eston Smith Jr
Messages
32
Reaction score
0
I'm in a rocket ship hovering at a non-black-hole Schwarzschild radius. The bottom half of my ship is inside the radius. I drop a straw. As the straw crosses the Schwarzschild radius, at mid-ship, it adds just enough mass within the radius to form a black hole. What would I see? Would the bottom half of my ship suddenly black out?
 
Physics news on Phys.org
If the Schwarzschild radius of the mass is inside the bounds of mass itself (i.e. it's not compact enough to be a black hole), you'd have to be doing something pretty magical to be hovering above it -- you'd be in it.

- Warren
 
I don't understand your response. The bottom half of my spaceship is part of the interior mass. The top half, with me and the feather, is part of the exterior mass. I drop the feather and it falls to the bottom half which is inside the radius. That additional interior mass is just enough to make the black hole form. So what happens next?
- Ray
 
The first sentence of your post is a contradiction due to you using the wrong definition of a black hole: if it has a Schwarzschild radius, then it already is a black hole. More on this in your other thread...
 
Too convenient. You would never see the 'straw' hit the event horizon. A time dilation thing.
 
Okay, you say the straw would "freeze" above the event horizon. But what about the bottom half of my spaceship? Would I have a breached hull? Would I be torn apart by tidal forces? All this because I dropped a straw? What about an observer on the other side of the radius? When I dropped the straw would his side of the sphere instantly become an event horizon (allowing me to use the straw in the hole to send a faster-than-light message) or would the event horizon formation spread from my side to his side at the speed of light? If he withdrew matter from the far side before the event horizon wrapped around it, would the event horizon then unwrap back around to me, telling me that it's not really a black hole after all? (These difficulties would not occur if the event horizon at a spatial radius of zero.)
 
If the feather were to fall on something and add just enough mass to that thing so that it collapses and forms a BH, then the EH of that BH would beb less than the original radious of the mass before the feather landed, wouldn't it?

So you couldn't have the feather fall onto the mass and make it collapse unless the original mass was inside your ship. If that were the case, then the mass that was occupying some amount of space inside your ship would now be replaced by a BH occupying less space inside your ship.
 

Similar threads

  • · Replies 73 ·
3
Replies
73
Views
2K
  • · Replies 89 ·
3
Replies
89
Views
6K
  • · Replies 114 ·
4
Replies
114
Views
9K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 44 ·
2
Replies
44
Views
4K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 63 ·
3
Replies
63
Views
5K
  • · Replies 6 ·
Replies
6
Views
1K