# Why wouldn't this simple idea to escape a black hole from below the event horizon work? **URL:** \ **Category:** Factual Questions\ **Created:** [August 26, 2009, 8:07pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809 "2009-08-26T20:07:27Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Stealth\_Potato](https://avatars.discourse-cdn.com/v4/letter/s/d78d45/32.png) [@Stealth\_Potato](https://boards.straightdope.com/u/Stealth_Potato)\ **Post date:** [August 27, 2009, 2:46am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/21 "2009-08-27T02:46:23Z")
> [@Xema](#): > > Right - but note that as you approach that infinite distance, you are also asymptotically approaching escape velocity. Only because the escape velocity approaches zero as distance approaches infinity. And in any case, you could always slam on the brakes now and then or simply use your magic fuel source to hold a single position for all eternity to disrupt the asymptote if you felt like being a mathematical contrarian. 😃 ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [August 27, 2009, 2:58am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/22 "2009-08-27T02:58:34Z")
A question (that possibly hijacks the thread): If protons have no mass, then how does gravity affect them? ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [August 27, 2009, 3:04am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/23 "2009-08-27T03:04:45Z")
> [@RadicalPi](#): > > A question (that possibly hijacks the thread): If protons have no mass, then how does gravity affect them? Protons certainly have mass, did you mean photons? ---
**Author:** ![ivn1188](https://avatars.discourse-cdn.com/v4/letter/i/e480ec/32.png) [@ivn1188](https://boards.straightdope.com/u/ivn1188)\ **Post date:** [August 27, 2009, 3:06am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/24 "2009-08-27T03:06:01Z")
> [@RadicalPi](#): > > A question (that possibly hijacks the thread): If protons have no mass, then how does gravity affect them? Photons, not protons. Gravity curves spacetime itself. The light travels in a straight line across a curved “surface”, which is why you get lensing, etc. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [August 27, 2009, 3:14am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/25 "2009-08-27T03:14:24Z")
As Chronos hinted at the light cone tips at the event horizon and in effect space and time trade places. Therefore no matter what you do you can’t avoid the singularity any more than you can escape tomorrow. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 27, 2009, 4:30am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/26 "2009-08-27T04:30:00Z")
> [@](#): > > Once something is inside, it effectively ceases to exist in this universe, which is why normal black holes can be described by only three variables – there is no other possible information we can obtain. Four variables, actually, and one of them is a (pseudo)vector, so there’s actually the equivalent of six scalars. But I’ll forgive you for thinking three: Everyone always forgets about magnetic charge, just because it appears that there aren’t any magnetic charges in the Universe. Still, that’s considerably less information than you can have in, say, a hydrogen atom. ---
**Author:** ![cerberus](https://avatars.discourse-cdn.com/v4/letter/c/71e660/32.png) [@cerberus](https://boards.straightdope.com/u/cerberus)\ **Post date:** [August 27, 2009, 6:09am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/27 "2009-08-27T06:09:49Z")
If it helps, think of the event horizon as a boundary: inside the boundary, space itself is so profoundly warped that conventional movement is impossible. ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [August 27, 2009, 6:31am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/28 "2009-08-27T06:31:32Z")
Falling into a black hole is almost like being eaten by a monster made of space-time. The closer you get to the event horizon, the more your local space curves around so that what’s “below” you (the event horizon) takes up more and more of your field of view, and your possible paths. Right above the event horizon, everything that would normally be in front, behind, and above you is condensed into a tiny circle, making it so there are many ways to go down and only a few ways to go up. Once you cross the event horizon, it swallows your whole field of view, so now the only possible direction to go is down. You can go slightly less down if you can remember which way was originally “up”, but ultimately you’ll find that the bottom of the black hole is literally in every direction you try to go. This is what is meant when it’s sometimes said that space and time switch places. The bottom of the black hole becomes a point in the future rather than a typical point in space, since inside, all possible paths through space-time eventually lead to it. Just like how here on Earth all possible paths through space-time will at some point lead to next Thursday, however fast or slow you go. ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [August 27, 2009, 7:37am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/29 "2009-08-27T07:37:48Z")
Thanks zombywoof and ivn1188. I did mean photons. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [August 27, 2009, 9:52am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/30 "2009-08-27T09:52:32Z")
> [@Chronos](#): > > Four variables, actually, and one of them is a (pseudo)vector, so there’s actually the equivalent of six scalars. But I’ll forgive you for thinking three: Everyone always forgets about magnetic charge, just because it appears that there aren’t any magnetic charges in the Universe. > > Still, that’s considerably less information than you can have in, say, a hydrogen atom. I wanted to ask for clarification on what exactly are these six scalars: The four variables you mention, I assume, are three directions (x,y,z) which define space - and time (T)? And, if time is your pseudo-vector, are you saying it has three components (or three scalars) giving a total of six scalars? Are these components Tx, Ty, and Tz…time along each direction of space? Or, did you have something else in mind? (Not a nit-pick, just wondering what else may be known about quantifying time-space.) ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [August 27, 2009, 10:01am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/31 "2009-08-27T10:01:56Z")
> [@enipla](#): > > I also don’t see why you need to reach c. > > Just travel at 10,000 a hour or so for as long as it takes. The same could be done on earth. With enough fuel, escape velocity could be 1mph. > > I’m not talking about the need to orbit either. Just go straight up, and keep going. Sounds simple enough, but you’re picturing someone driving from pt A to pt B at only 1mph. This is possible, but slow. Now, going striaght up, you are doing work against earth’s gravity. So, going 1mph won’t cut it. If that were possible, then a pitcher throwing a 90mph fast ball could launch baseballs into orbit, or beyond. Ultimately, you need to accelerate to reach escape velocity. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [August 27, 2009, 10:15am UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/32 "2009-08-27T10:15:20Z")
Posted here [Tesseract - Wikipedia](http://en.wikipedia.org/wiki/Tesseract) is perhaps the closest visual demonstration as to how space and time can reverse themselves. This is a rotating image of a hypercube. I see a small cube inside a larger cube, but as the image rotates, it looks like the inner cube is (a) pushed out the near side of the larger cube while (b) the larger cube is pulled in to reform the inner cube. (This is the best I can describe what I think I see.) Watch this for awhile and see what illusion you see. (Sorry, I couldn’t get the “post link” feature working correctly.) You may need to scroll down the page. The image is in the right margin. Note: This was not meant to be such a demo, but it is…to me! ---
**Author:** ![Uncertain](https://avatars.discourse-cdn.com/v4/letter/u/6a8cbe/32.png) [@Uncertain](https://boards.straightdope.com/u/Uncertain)\ **Post date:** [August 27, 2009, 12:37pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/33 "2009-08-27T12:37:18Z")
> [@Jinx](#): > > Now, going striaght up, you are doing work against earth’s gravity. So, going 1mph won’t cut it. If that were possible, then a pitcher throwing a 90mph fast ball could launch baseballs into orbit, or beyond. Ultimately, you need to accelerate to reach escape velocity. Major League Baseball does not permit the use of balls with thrusters (though the American League, to the chagrin of purists, is considering it). ---
**Author:** ![groman](https://avatars.discourse-cdn.com/v4/letter/g/73ab20/32.png) [@groman](https://boards.straightdope.com/u/groman)\ **Post date:** [August 27, 2009, 12:45pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/34 "2009-08-27T12:45:06Z")
> [@Jinx](#): > > Sounds simple enough, but you’re picturing someone driving from pt A to pt B at only 1mph. This is possible, but slow. Now, going striaght up, you are doing work against earth’s gravity. So, going 1mph won’t cut it. If that were possible, then a pitcher throwing a 90mph fast ball could launch baseballs into orbit, or beyond. Ultimately, you need to accelerate to reach escape velocity. Simply put, escape velocity is a function of a massive object and location relative to that massive object. If you define escape velocity as being always where **you** are in relation to the planet or whatever you are trying to escape, then yes, you have to accelerate to escape velocity to _escape_. If you define escape velocity as being always where **you started** , then no, you don’t have to reach it. I don’t have to reach 11.186 km/s with respect to Earth to escape Earth. I can do it by maintaining 1 mm/s with respect to Earth if I could achieve such a feat – eventually escape velocity where I will be at will fall below 1 mm/s, so I would “reach escape velocity” but I think that’s a rather silly way of putting it. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [August 27, 2009, 1:08pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/35 "2009-08-27T13:08:30Z")
> [@The\_Tao\_s\_Revenge](#): > > On earth you want to journey to the moon, but you’re old and frail and would never survive the acceleration needed to reach earth escape velocity. So you develop a fuel energetic enough to give a slow 1.01 G acceleration all the way to the moon. Thus you’ve escaped earth’s gravity without reaching escape velocity. > > Assuming strong enough fuel, couldn’t a black hole’s event horizon be escape in a similar manor? > > I’m thinking maybe my understanding of event horizons is off. Your question is kind of like “why can’t I lower a rope into the event horizon of a black hole and slowly climb out?” A fair enough question. It’s more useful to think in terms of paths in space than velocity because just considering velocity implies that you can still escape if you just go fast enough or long enough. As you may know, mass deforms space. As you get closer to a body of mass like a planet, there are fewer paths that will take you away from the planet’s center of gravity. With a black hole, once you go passed the event horizon, space has becomed warped to the extent that there are no longer any paths away from the center of the black hole. All roads, in a sense, now lead to the singularity at the center. [Here is a useful illustration.](http://en.wikipedia.org/wiki/File:BH-no-escape-1.svg) Ff I were to lower you into a black hole on a rope, from your point of view you would never seem to reach the event horizon. I, OTOH, would apear to be infinitely far away. From my point of view you would disappear across the event horizon and the rope would simply break somewhere on my side of the EH if I tried to pull you back. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [August 27, 2009, 1:11pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/36 "2009-08-27T13:11:39Z")
> [@Jinx](#): > > I wanted to ask for clarification on what exactly are these six scalars: The four variables you mention, I assume, are three directions (x,y,z) which define space - and time (T)? And, if time is your pseudo-vector, are you saying it has three components (or three scalars) giving a total of six scalars? Are these components Tx, Ty, and Tz…time along each direction of space? Or, did you have something else in mind? (Not a nit-pick, just wondering what else may be known about quantifying time-space.) No, the four variables he mentions are mass, electric charge, angular momentum, and magnetic charge, which are the only characteristics by which black holes _can_ differ from each other, and the first three of which are the only characteristics by which they actually _do_ differ from each other. 😛 (cf. [No-hair-theorem](http://en.wikipedia.org/wiki/No_hair_theorem)) ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [August 27, 2009, 1:13pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/37 "2009-08-27T13:13:04Z")
> [@Jinx](#): > > Sounds simple enough, but you’re picturing someone driving from pt A to pt B at only 1mph. This is possible, but slow. Now, going striaght up, you are doing work against earth’s gravity. So, going 1mph won’t cut it. If that were possible, then a pitcher throwing a 90mph fast ball could launch baseballs into orbit, or beyond. Ultimately, you need to accelerate to reach escape velocity. Exactly. We are NOT talking about a conventional launch, but, as you put it ‘A person driving from point a to point B’. So escape velocity has nothing to do with it. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [August 27, 2009, 1:18pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/38 "2009-08-27T13:18:04Z")
[Some interesting videos.](http://jilawww.colorado.edu/~ajsh/insidebh/schw.html) ---
**Author:** ![ExTank](https://avatars.discourse-cdn.com/v4/letter/e/35a633/32.png) [@ExTank](https://boards.straightdope.com/u/ExTank)\ **Post date:** [August 27, 2009, 1:22pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/39 "2009-08-27T13:22:19Z")
> [@Stealth\_Potato](#): > > Well, yes, but it no longer applies to you because you are moving under thrust. If you have continuous thrust instead of a single initial speed, you needn’t ever meet or exceed the escape velocity _at any point_ with respect to the body in order to come to rest an infinite distance away from it, asymptotically speaking. I hate it when people speak asymptote. ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [August 27, 2009, 1:47pm UTC](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809/40 "2009-08-27T13:47:00Z")
Never mind [Previous page](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809.md?page=1) [Next page](https://boards.straightdope.com/t/why-wouldnt-this-simple-idea-to-escape-a-black-hole-from-below-the-event-horizon-work/507809.md?page=3)