I've got my FTL boots on (another silly black hole question)

In summary: I'm not sure if he still holds to that view.Anything free falling into a black hole will perceive light from the outside is redshifted. You would have to be stationary to see it blueshifted, which is of course impossible for an object in free fall.
  • #1
Spourk
55
0
Good Afternoon, to those of you that are existing in the afternoon. For all else, good morning, good evening and so on.

Before I begin, this is more of a question about the behavior of light in immense gravity than anything else. I'm well aware that under the best of circumstances, or the worst, I'm spaghetti'd and anyone outside observing me fall into a black hole will see me slow down and turn red. I mean, after all, it IS pretty embarassing to voluntarily point your self at a black hole and fall in.

Alright, to the meat and potatoes, as they say.

I've got my FTL boots on. I'm falling into a black hole. Nevermind an outside observer, I'm hoping there are none to record my silly actions from this point forward.

Right as I pass the EH falling toward the singularity, I flip my FTL boots on and I hover, just inside the EH and take a gander back at the universe.

Nevermind that in mere seconds I will realize that my logic is completely wrong, and my FTL boots will cease to exist and I shall be sucked into the singularity against all whims or wishes.

My question is, what do I see as the light falls into the Black Hole and hits me, hovering just inside the EH?

I've read Larry Niven's "Neutron Star" and in it, as I'm sure anyone who's read it knows, the light falling on the ship passing close to the star ends up giving the pilot/astronaut "star burns".

Because I'm able to hover in my ill-logic for a couple seconds, and I'm not falling at the speed of light, is the light blue shifted?

Thanks for your patient answers. :)
 
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  • #2
Take a look here for a realistic view of falling into a black hole: http://casa.colorado.edu/~ajsh/schw.shtml
 
  • #3
Drakkith said:
Take a look here for a realistic view of falling into a black hole: http://casa.colorado.edu/~ajsh/schw.shtml

Hi Drakkith, thank you for that link. I'm actually pretty familiar with Andrew Hamilton's site, however, I can't seem to find an answer that tells me what the behavior of observed light is hovering just inside the EH. I'm pretty sure that as you fall into the singularity, if you were somehow able to observe the light falling in as you fell it would be red shifted, since it has to catch up with you as you fall at the speed of light.

I'm curious to know that if you aren't falling, and yet stuck just inside the EH, is the light blue shifted? More intense/bright because it's trapped there etc?

Edited to add: I'm also aware that the answer is probably in there somewhere, it's just not very apparent to a layman like myself.
 
  • #4
Not sure honestly. Off the top of my head I would guess that the light is more blue shifted since you aren't moving away from it anymore, but that's just a guess.
 
  • #5
Anything free falling into a black hole will perceive light from the outside is redshifted. You would have to be stationary to see it blueshifted, which is of course impossible for an object in free fall.
 
  • #6
Hovering inside the horizon of a black hole is impossible, so asking what you'll see makes no sense.
Still a small region of spacetime inside a black hole will look no different to you than a region outside the black hole, and you can still get the light as blue-shifted as you want by accelerating hard enough.
 
  • #7
Chronos said:
Anything free falling into a black hole will perceive light from the outside is redshifted. You would have to be stationary to see it blueshifted, which is of course impossible for an object in free fall.

Actually that answered it perfectly for me, thanks Chronos. My FTL Boots would hold me right inside the EH, so I would not be falling at that point. (Until logic kicked in and with a terrible realization the whole "got my ftl boots on" thing becomes apparently impossible and I do get spaghettified immediately after). I would be stationary at the EH, so would the light not be blueshifted at that point, since I'm facing away from the singularity and the light would be trapped as it came towards me?

Chronos said:
Hovering inside the horizon of a black hole is impossible, so asking what you'll see makes no sense.

Well. It could be said that following a beam of light is impossible too, and yet, that impossible thought experiment changed physics. (Einstein). Sometimes people, curious people especially, like to use an impossible situation to get a better understanding of the concept as a whole, so I'd tend to disagree. Also, you might want to address that with Andrew Hamilton, as he actually visualized the impossible, falling into a black hole AND rendering a visual of it for all to see. ;) (Impossible being that nothing can send back that kind of information from inside a black hole)
 
  • #8
I would say that your view would be no different from any point of the universe. I do not know why you should see something differet as far as i understand physics.
 
  • #9
minio said:
I would say that your view would be no different from any point of the universe. I do not know why you should see something differet as far as i understand physics.

Can you explain that a little further?

Considering you get an Einstein ring around a black hole or neutron star just approaching it, your view of the universe is already drastically changed by the immense gravity's effects on the light around a black hole. As you're falling into a black hole, light would be red shifted because you're moving at the speed of light already, (once you pass the EH and are doomed to hit the singularity), and that light has to catch up to you as you fall in. Both the redshift, and the Einstein ring are examples of a very different view from in and around a black hole.
 
  • #10
We don't have to use FTL boots to keep us from falling into the black hole to see the effects on light. Simply accelerating against the gravity will allow us to see the light being less redshifted than when we were freefalling.
 
  • #11
Spourk said:
Actually that answered it perfectly for me, thanks Chronos. My FTL Boots would hold me right inside the EH, so I would not be falling at that point. (Until logic kicked in and with a terrible realization the whole "got my ftl boots on" thing becomes apparently impossible and I do get spaghettified immediately after.
Much like the cartoon character who runs off the cliff and hovers in air until he realizes there is no ground under him?
 
  • #12
HallsofIvy said:
Much like the cartoon character who runs off the cliff and hovers in air until he realizes there is no ground under him?

Exactly! He has a few moments of false lucidity to consider, and then remembers Newton in a stomach lurching drop, resulting in a small poof somewhere down... there...

wile_e_coyote_gravity.jpg
 
  • #13
Drakkith said:
We don't have to use FTL boots to keep us from falling into the black hole to see the effects on light. Simply accelerating against the gravity will allow us to see the light being less redshifted than when we were freefalling.

Agreed. The only reason I used the "FTL boots" was to keep ahead of the gravitation pull, (gotta move faster then the speed of light to not be sucked in completely). I really just wanted to understand more about the behavior of light around the EH.

This was all inspired to me by Larry Niven's "Neutron Star". I thought it was a brilliant detail to add in how badly blue shifted the light was in the vicinity of the Neutron Star, being that it has a harder time escaping there, than in pure vacuum.
 
  • #14
Spourk said:
This was all inspired to me by Larry Niven's "Neutron Star". I thought it was a brilliant detail to add in how badly blue shifted the light was in the vicinity of the Neutron Star, being that it has a harder time escaping there, than in pure vacuum.

Harder to escape the neutron stars gravity than pure vacuum? I don't follow you.
 
  • #15
Drakkith said:
Harder to escape the neutron stars gravity than pure vacuum? I don't follow you.

Bah, bad wording there. I meant that the light has a harder time escaping/moving through the neutron star's gravity than moving through vacuum, hence the blue shift. Apologies for the confusion! :)
 
  • #16
Spourk said:
Bah, bad wording there. I meant that the light has a harder time escaping/moving through the neutron star's gravity than moving through vacuum, hence the blue shift. Apologies for the confusion! :)

The light is blue shifted because it is heading into a gravity well and gains energy. Which is only noticeable if the observer is also inside the gravity well. If you were on the opposite side of the neutron star from a flashlight the light would appear the correct color, as it gained then lost energy equally as it made its way to you. It doesn't really have a "harder" time moving through this than open space nowhere close to a massive object.
 
  • #17
Drakkith said:
It doesn't really have a "harder" time moving through this than open space nowhere close to a massive object.

This part confused me a little bit, the rest of your post made a lot of sense. I guess by "harder time" I meant that light gets altered around a massive object, hence the disturbance in it's path. It really ends up being rhetoric, (on my part, not yours, I just don't have the terminology to frame it correctly), but in the end I understand exactly what you're saying, and it actually adds a lot of clarity to my concept of light around massive objects.
 
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  • #18
In free fall, by the time you reach the event horizon you are also traveling near light speed, so light from the outside is struggling to keep up.
 
  • #19
Has anyone here read "Neutron Star"?

Would blue shifted light actually be harmful if you were exposed to it going close to c?

Or stuck in a gravity well for that matter, around a Neutron star...

I mean, nevermind tidal effects, mass increase, dust particles nipping you and causing thermonuclear reactions...
 
  • #20
Spourk said:
Would blue shifted light actually be harmful if you were exposed to it going close to c?

Absolutely. Get to a high enough speed and the microwave radiation background blue shifts into high energy gamma rays.
 
  • #21
Drakkith, what is up with your icon? Are you a Doom player? }=D (I love Doom)
 
  • #22
Spourk said:
Drakkith, what is up with your icon? Are you a Doom player? }=D (I love Doom)

Is it from Doom? I thought so, but wasn't 100% sure. I used to play Doom as a kid.
 
  • #23
Drakkith said:
Is it from Doom? I thought so, but wasn't 100% sure. I used to play Doom as a kid.

You can still play it! :D Check out "www.zdaemon.org" [Broken]. It's basically a multiplayer Doom interface, and you can pick up .wad files just about anywhere.
 
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  • #24
Spourk said:
You can still play it! :D Check out "www.zdaemon.org" [Broken]. It's basically a multiplayer Doom interface, and you can pick up .wad files just about anywhere.

I have the whole series on Steam I think. But anways, back to the topic, did you have any more questions regarding blueshift and redshift or anything?
 
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  • #25
Drakkith said:
I have the whole series on Steam I think. But anways, back to the topic, did you have any more questions regarding blueshift and redshift or anything?

Nope, sorry to deter from the topic, that was mostly a personal curiosity.

My own question was answered, though, and thanks. :)
 

1. What are FTL boots?

FTL boots are a fictional concept often used in science fiction, which stands for Faster Than Light boots. These boots are designed to allow the wearer to travel at speeds faster than the speed of light, which is currently thought to be impossible according to the laws of physics.

2. How do FTL boots work?

As FTL boots are purely fictional, there is no scientific explanation for how they work. In most science fiction stories, FTL boots are often powered by advanced technology or some sort of energy source that allows them to manipulate space and time to achieve faster than light travel.

3. Can FTL boots really exist?

Currently, there is no scientific evidence or technology that suggests FTL boots could exist in reality. The concept of faster than light travel goes against the laws of physics, and it is not yet known if it will ever be possible to achieve such speeds.

4. Are FTL boots similar to black holes?

No, FTL boots and black holes are two completely different concepts. Black holes are objects in space with such strong gravitational pull that not even light can escape, while FTL boots are a fictional technology that allows for faster than light travel.

5. Are there any real-world applications for FTL boots?

No, as FTL boots are currently only a fictional concept, there are no real-world applications for them. However, the idea of faster than light travel has been explored in scientific research and could potentially have implications for space exploration and understanding the universe in the future.

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