Everything you need to know about Black Holes - PART 2

  Hey guys! I am Rahul and I am back again with the second part of the series “Everything you need to know about Black Holes” as promised. In this part I will be telling you what will happen if we fall into a black hole.  

For part 1 click here.

  Okay so today we(Yes you and me) will be jumping inside the black hole and we will see what happens to us once we are inside. First things first, any object in this universe can become a black hole if and only if we compress it so much that there is no space left between its constituent particles. Every object having some mass, say M, has a Schwarzschild radius. If that object is compressed so that its size becomes less than that, it becomes a black hole. Schwarzschild radius(R) is given by following formula:  

                                                   R=2GM/c2  

                       (G is gravitational constant, c is speed of light) 

The center of a black hole is called singularity. It is infinitesimally dense.  

Okay so before jump into a black hole let’s see how it looks from outside. Since in reality we have never encountered a black hole so we don’t really know how it looks like from outside but thanks to Einstein’s Theory of General Relativity, which explains how space and time behaves under action of strong gravity, we can predict the consequences without actually rendezvousing with one. So as you know in his theory he said that fabric of space curves in the presence of gravity, energy, matter and momentum. It looks something like this: 

 

Source

  Due to this bending of space, as shown in the following image the path of light coming from a far away star also bends due to the gravitational pull of our sun.  

   

Source 

  Due to which the star appears to be somewhere else in space. This phenomenon is called gravitational lensing.   So now after learning some laws of physics we can predict how a black hole wandering in space will look like from outside. It will look something like this:  

Source

  As you can see when the black hole comes in front of the galaxy, everything around it looks distorted. Now what happens is that the light coming from the galaxy bends because of the enormous gravitional pull of black hole. This bending of light is highly significant unlike the bending due to our own sun. The light is contorted, twisted and distorted and makes the far away galaxy look like a ring.  

Okay so after finding a black hole wandering in space let’s go near it. Assume that both of us are in a spaceship like this  

 

Source                          

  After a while we would have reached photon sphere. Its that area from where light neither gets sucked inside the black hole and nor it can escape from its clutches. In this sphere light can only orbit the black hole. Once we are inside the photon sphere and you look on your side, theoretically you can actually see the back of your head. I know right now you will be like  

 

 We haven’t reached to our destination(inside black hole) yet. You know what? If you are that scared let me help you. Now instead of both of us, only I will be going inside the black hole.  

 

  You just observe from outside that what happens to me as I get more closer. 

As I am getting more closer and closer I am getting more close to event horizon. Event horizon is that boundary around a black hole beyond which no light or other radiation can escape. That is there is no coming back for me. A gravitational field not only warps space, it also warps time which causes time dilation. For the sake of simplicity let’s just only see its definition. Time dilation means that if someone(say A) is travelling with a speed x respective to say B, then the clock for person A will tick slower than the clock of B. That is time gets slower w.r.t someone else if we are travelling with some speed w.r.t to someone else.  

Since when I will be getting more closer my speed will also be increasing due to high gravitational pull of black hole. So as a observer what you will see is as I approach event horizon I am getting slower and slower until I reach event horizon because time is ticking slower for me. I would seem almost frozen in space. The light coming out off my body will be becoming red shifted until I fade into nothingness. You will never see me crossing the event horizon. Surprising huh! But it is true.  

But for me observation is little different. For me time is passing as usual. I am getting closer more quickly than ever for my inevitable death. Once I am inside event horizon and now going near the singularity where all the mass is concentrated the view of the universe behind me will be getting smaller and smaller. 

 

Source

  If a black hole is big enough I will be quite comfortable inside it until is starts to hurt. But why will it hurt me? Because as I am getting more closer to singularity the difference between gravitational pull at two positions is also becoming more significant. The gravitational pull on my feet would be so much stronger than that on my head that I would be pulled apart like string cheese pretty quickly. This  vertical stretching and horizontal compression according to the scientists is called sphagettification.   

 

Source

  But what once I reach the singularity. Well even physicists don’t know what will happen then. Maybe I will completely disappear in violation of all the laws of physics or maybe I would reappear elsewhere in the universe. Some people believes that a moving or spinning black hole might actually create what is known as “wormhole”, a way of teleportation i.e. travelling faster than light in other words. 

What’s your opinion? What do you think will happen? Or are we missing something? Tell me in comments section. 

Tomorrow I will be uploading the Part 3 of this series. 

So don’t forget to follow me and upvote and resteem it if you really like it. 

signing off......  @rahulk200013