Time dilation and spaghettification

**Effects of gravity#1**

 What is Time Dilation?

'Is it possible for a person to survive a black hole alive?'

Well, the answer to this simple question is clearly 'No'. Reason? It's Time dilation. Time dilation is a phenomenon where time practically slows down and becomes infinitely curved. This curvature of space-time is a result of the black hole's infinite density (see Time Warp in black holes). The effect of time dilation changes the linear characteristic dimension of time and makes it highly curled up or stretched, which in turn causes you to be stretched vertically and squeezed horizontally, a process we call spaghettification.

We live in a four-dimensional universe where the first three dimensions include length, breadth and height. These three parameters represent the x, y and z axes of our cartesian plane. Then what about the fourth dimension? Of course, it's time. As the direction of time is linear (because time cannot travel backwards or can be stopped), we live in a scenario where time always goes on in a forward and uniform manner. This perspective of space-time changes in the case of black holes. 

The density of the black holes causes time dilation where time gets 'bent'. For a person that falls into the black hole, he will feel his whole body being stretched slowly along space-time. As he falls further into it, the stretching pull will get more intense. More likely, if the person is falling onto the black hole in his standing position, the gravitational pull on the person's foot will be more compared to his head, and because of the slowing time, he will be stretched like spaghetti by the time he reaches the event horizon. 

This process is called spaghettification. 

So, before he knew it, he would be drawn like a thread and unfortunately, that would be the end of his life. Now, a viewer far away who is viewing the whole incident won't see the person being ripped, but instead, the viewer will see the person falling in much slower and will notice that the person appears to be reddish and fainter until he finally fades away from viewer's point of vision. This is another effect of time dilation. This happens because time is not as slower (curved) as it is near the black hole. Einstein's general theory of relativity also predicts this effect of gravity on time.

 

 The reddish appearance of an object whilst falling into a black hole is because the light rays emerging from the object are also being elongated or stretched due to time dilation or the effect of relativity. Since red is the longest wavelength, the light waves from the object appear to be reddish to the viewer's eye. This phenomenon is called the 'red shift'. Black holes and distant galaxies can create large redshifts.