The center of a black hole is not so much a place as  a moment in time. It is literally as inescapable as tomorrow.

The center of a black hole is not so much a place as  a moment in time. It is literally as inescapable as tomorrow.

Originally shared by Jonah Miller

Falling into a black hole with a flashlight.

It’s a common misconception that, because an observer falling into a black hole appears to stop, time stops for that observer. That’s not really true.

Think of it this way. The event horizon is the point where light cannot escape the black hole, right? Well, suppose I jump into a black hole carrying a flashlight and you watch. As I get closer to the event horizon, the light rays from my flash light will have a harder and harder time getting away from the black hole to your eyes.

Eventually, they won’t be able to get to your eyes at all… after I pass the event horizon. But, the instant before I fall in, the light rays will take a huge, but finite time to reach you. 

The effect is that, for the age of the universe, you will see the light rays I emitted just before I passed the event horizon. And I will appear to have stopped.

Past the event horizon

Although to outside observers, I appear to have stopped. I may not actually notice anything strange as I pass the event horizon (depending on the size of the black hole). I will eventually be torn apart by tidal forces, but for a large black hole, these are weak near the event horizon.

From my perspective, I’m just travelling through space, and I experience time somewhat normally. This is the difference between proper time and coordinate time. Proper time is the time experience by a person. Coordinate time is just a label.

However, one strange thing will happen to me inside the black hole… and that is that the singularity, the center of the black hole, is irrevocably in my future. The center of a black hole is not so much a place as  a moment in time. It is literally as inescapable as tomorrow.

This post was inspired by a question on the Science on Google+ community by Dustin Thurston . Original post here:

https://plus.google.com/u/0/100608294723698772664/posts/iTKKMR5HPVb

Image is a simulation of gravitational of the milky way by a black hole. (Said black hole does not exist.) The creator, Ute Krauss, has a 

lot of great relativity visualizations. You can find them here:

http://www.spacetimetravel.org/expeditionsl/expeditionsl.html

Source: The description I just gave can be found in most general relativity textbooks. For a free treatment, I recommend Sean Carroll’s lecture notes, published online:

http://preposterousuniverse.com/grnotes/

#physics   #astrophysics   #science  

Join the Conversation

35 Comments


  1. I feel as if my life has entered into a BLACK HOLE and no matter what I do I can’t just stop time so there won’t be a tomorrow because for some reason tomorrow never becomes better than today.


    Fortunately I’m able to forget about yesterday because of my mind being in the early stage of dementia so I’m able to forget yesterday’s troubles due to the fact I have absolutely no short term memory.


    Falling into the BLACK HOLE could be an advantage to me because it causes TIME TO SLOW DOWN,,,


    Reminds of the old TV series from the 70s called,,,


    THE TIME TUNNEL

    Like


  2. Hey Jonah Miller,,,


    I just have to say that for a brief moment in time my life gave me peace of mind.


    All because of the words of concern and hope you sent me from your heart.


    I THANK YOU MY FRIEND AND MAY GOD BLESS YOU.


    I believe life is all about how you perceive it to be.


    A problem only becomes a problem when you perceive it to be a problem.


    I have no problems,,, Only challenges,,, and if I can beat this challenge I will receive a gift,,, a gift of knowledge and with knowledge comes WISDOM,,, and with WISDOM comes answer’s and with answers comes ACCEPTANCE,,, That’s where I’m at in my mind at this exact moment in time,,, THANK GOD,,,


    I’D TAKE DEMENTIA ANY DAY OVER CANCER,,,


    Very interesting post Johna,,, keepem coming my friend,,,


    GODNIGHT TO ALL,,,

    Like


  3. Igor Kolosha​ Roger Harris​ nobody knows what happens when you reach the singularity.


    Wade Willson​ that’s not true. The image a distortion of the light from the galaxy behind the black hole due to gravitational lensing.

    Like


  4. Wade Willson mind your language. We know that it is an artist’s image.  Jonah Miller was responding to your second point, that “in reality you wouldn’t see anything”. He explains how the image illustrates “gravitational lensing”. Hope this makes sense now. 

    Like


  5. Roger Harris for a true singularity, the spacetime ends, this is true. But most likely a singularity indicates that our mathematical description breaks down near the center of a black hole.

    Like


  6. Tomorrow is very escapable. If you’re in a frame where timing against the rotation of the earth’s rotation in the frame of the sun doesn’t make sense, then you’ve escaped tomorrow. By contrast, you can’t even get to the event horizon of a black hole, much less leave it. 

    Like


  7. Also, just a point of clarification, time stops at the event horizon, (also the schwarzschild radius), hence the name. If there is anything inside of the event horizon, it’s either violating relativity or not observable to the rest of the universe. 

    Like


  8. Charles Bosse , the sunrise is escapable. The future is not. 😛


    Time does not stop at the event horizon (which by the way is the same as the Schwarzschild radius for a Schwarzschild black hole.) That is the whole point of my post. If something passes behind the event horizon, it is never accessible again and, as you say, it is not observable. But that doesn’t mean time stops!

    Like


  9. Roger Harris interesting. I was not expecting that article to take the track it did.


    Here’s my perspective. Infinity is not so much a number as it is an algorithm. It is a self-consistent statement saying that “no matter what number you give me, I can make a bigger one.”


    In physics, infinity is a tool, with no true physical meaning. But it is a tool that makes many many calculations vastly easier… Mathematics without the infinitessimally small is ridiculously difficult, though often very powerful.


    So to me, these philosophical discussions about the physical meaning of infinity are a little strange. Nature tells us what it is like. In the world of physics, mathematics is the language in which Nature speaks, but that is all.


    (Obviously mathematics has merit beyond this crude description. But to a physicist, this is what matters.)

    Like


  10. Jonah Miller time, as Einstein (and most physicists) define it does indeed stop at the event horizon, as the interactions that we use to create the concept of ‘time’ as defined in the rest of our experience becomes undefined. Interactions can only happen in one direction, at the event horizon, and so anything beyond that ceases to exist through any known interaction (gravity is only a “probably” here, but as far as we know, ‘c’ applies to gravitation too).


    If you’re approaching a black hole time will not stop for you, of course. If you could continue to make observations in that hostile environment time would appear to speed up until the the entire time to the evaporation of the black hole elapsed in a single “flash” that is to “blinding” as the width universe is to a plank length. Of course, well before you ever reach that point, things like “photons” will have started to loose all meaning, much less the distinction between mass and energy, so you can’t exactly just jump in and find out. 

    Like


  11. Charles Bosse 


    You say:


    time, as Einstein (and most physicists) define it does indeed stop at the event horizon


    I am a working physicist, studying gravity. I actually do know what I’m talking about.


    You say If you’re approaching a black hole time will not stop for you, of course


    Yes. That’s exactly my point.


    You say:


    If you could continue to make observations in that hostile environment time would appear to speed up until the the entire time to the evaporation of the black hole elapsed in a single “flash” that is to “blinding” as the width universe is to a plank length.


    I’m not really sure where you’re getting this idea from. You may be thinking that time dilation increases as you approach the singularity… but as I said above, the singularity is probably nonphysical. Trying to say that it causes you to observe the black hole evaporate is… tenuous.

    Like


  12. Charles Bosse 


    Yous say:


    I mean ” stop” like you might say division stops at a zero denominator.


    ..what? That implies some quantity diverges or becomes ill defined. But, as I keep saying, that’s not the case at the event horizon of a black hole.


    You say:


    Time dialation does increase as you approach a singularity, at least until you reach the event horizon. If you continue approaching the event horizon, incoming signals will pile up on each other and seem to come in at the same time, until the pile up ends (the black hole evaporates). Thus the seeming flash. This happens as you approach the event horizon asymptomaticly, and has nothing to do with the physicality of the event horizon itself.


    The very point of my post is that this does not happen. You are getting confused (as I describe in my post) about the difference between time experienced by the in-falling observer and what an observer far from the black hole sees. They are very different!

    Like


  13. Charles Bosse it depends on the observer. The person viewing far away sees the motion near the event horizon slow down and eventually stop. But this is, in some sense, an illusion due to that observer’s incomplete information.


    The person actually falling into the black hole experiences things very differently. That observer sees things far away accelerate. But near the black hole, the doomed in-falling observer doesn’t see anything strange.


    This is a really hard idea and it took physicists many decades to understand after Karl Schwarzschild wrote down the equations for a black hole.


    I’m struggling to find an intuitive way to explain this without invoking the equations, which I don’t want to do. So I’m afraid for now, you’re going to have to take my word for it. But I’ll try and think about what I can say.

    Like

Leave a comment

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: