Is it possible to pull something out of a black hole? (Synopsis)

“Nobody ever did, or ever will, escape the consequences of his choices.” -Alfred A. Montapert

So you’re passing by a black hole in a massive, fast-moving spaceship, and you want to do an experiment: you tether a small mass outside of the ship and let it fall into the black hole, just allowing it the tiniest bit inside, while your ship takes off to try and escape. If you can keep the tether from breaking and your ship from getting stretched apart, what’s going to happen?

Even something as massive as a star, if brought too close to a black hole, will find itself stretched-and-compressed into a long, thin filament: spaghettified. The effects on a human being are equally severe if the black hole is low enough in mass. Image credit: ESO, ESA/Hubble, M. Kornmesser.

Will you manage to make off with your object, despite dipping it into the abyss, perhaps even obtaining information about the inside of the black hole in the process? Or will the gravitation of the black hole inevitably suck you in, forcing you to either cut the tether or wind up at the core singularity, where you’ll be unable to avoid being torn apart?

Once you cross the threshold to form a black hole, everything inside the event horizon crunches down to a singularity that is, at most, one-dimensional. No 3D structures can survive intact. Image credit: Ask The Van / UIUC Physics Department.

Physics holds the answer, and one thing is clear: don’t bet against the laws of Einstein!

More like this

Ethan Siegel wrote: "No matter how much energy you have, you can never move faster than the speed of light"

Can you deduce this explicitly from Einstein's 1905 two postulates, by a series of valid logical steps? If not, do you repeat it just because people around you often repeat it?

By Pentcho Valev (not verified) on 07 Jul 2017 #permalink


MM experiment shows speed of light is constant and independent of observers. Which leads to Special Relativity where its equations show to reach speed of light, one would need infinite amount of energy.

Also out of curiosity:
Have you ever read the famous classic novel "Don Quixote"?

Frank wrote: "MM experiment shows speed of light is constant and independent of observers."

No. Initially, the Michelson-Morley experiment UNEQUIVOCALLY confirmed the variable speed of light posited by Newton's emission theory of light; later Lorentz and FitzGerald introduced ad hoc idiocies - length contraction etc., confused everything and paved the way for Einstein's science killing "theory":

Wikipedia: "Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. [...] The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)."

John Norton: "The Michelson-Morley experiment is fully compatible with an emission theory of light that CONTRADICTS THE LIGHT POSTULATE."

Banesh Hoffmann, Relativity and Its Roots, p.92: "Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether. If it was so obvious, though, why did he need to state it as a principle? Because, having taken from the idea of light waves in the ether the one aspect that he needed, he declared early in his paper, to quote his own words, that "the introduction of a 'luminiferous ether' will prove to be superfluous."

Albert Einstein: " is impossible to base a theory of the transformation laws of space and time on the principle of relativity alone. As we know, this is connected with the relativity of the concepts of "simultaneity" and "shape of moving bodies." To fill this gap, I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz's theory of the stationary luminiferous ether..."

Yes I have read "Don Quixote" - we even analyzed it at school, many years ago.

By Pentcho Valev (not verified) on 07 Jul 2017 #permalink


Maybe study some logic too? The MM experiment most certainly did NOT conclusively demonstrate emission theory. It was consistent with emission theory, but other experiments ruled out emission theory. The MM experiment is also (obviously) consistent with the isotropy of light speed. Deciding between isotropy and emission theory required other experiments. These came down on the side of isotropy.

Pentcho valev

The factor relating rest mass and accelerated mass is tau (t).

accelerated mass= rest mass * 1/t

t =1-(v^2/c^2)

v is the velocity of your spaceship and c is the speed of light.

This is non-linear. At 86% off mass doubles, but beyond that velocity tau drops rapidly and mass increases rapidly as you go faster.

When v=c tau goes to zero and accelerated mass= rest mass * 1/0 = infinity.

At c it takes an infinite amount of energy to accelerate that intfinite mass. Therefore no further increase in velocity is possible.

By Entropic man (not verified) on 07 Jul 2017 #permalink

Sean T wrote: "The MM experiment most certainly did NOT conclusively demonstrate emission theory."

Of course. It proved just an aspect - the variation of the speed of light posited by the emission theory. And accordingly disproved the antithesis - the constancy of the speed of light posited by the ether theory and later adopted by Einstein as his second postulate.

The term "Newton's emission theory of light" is somewhat misleading, even a red herring. In fact there is no consistent model so the "theory" cannot be falsified as a whole. Only aspects of it can be tested, and the confirmation or refutation of an aspect is irrelevant to the confirmation or refutation of another aspect. The term was introduced by Einstein in 1909:

Albert Einstein 1909: "A large body of facts shows undeniably that light has certain fundamental properties that are better explained by Newton's emission theory of light than by the oscillation theory. For this reason, I believe that the next phase in the development of theoretical physics will bring us a theory of light that can be considered a fusion of the oscillation and emission theories. The purpose of the following remarks is to justify this belief and to show that a profound change in our views on the composition and essence of light is imperative. [...] Then the electromagnetic fields that make up light no longer appear as a state of a hypothetical medium, but rather as independent entities that the light source gives off, just as in Newton's emission theory of light. [...] Relativity theory has changed our views on light. Light is conceived not as a manifestation of the state of some hypothetical medium, but rather as an independent entity like matter. Moreover, this theory shares with the corpuscular theory of light the unusual property that light carries inertial mass from the emitting to the absorbing object."

By Pentcho Valev (not verified) on 07 Jul 2017 #permalink

@Pentcho Valev

Can you deduce this explicitly from Einstein’s 1905 two postulates, by a series of valid logical steps?

Can you? Because if you can't even follow the math on Wikipedia, then you're in position to be dismissing the theory.

By Naked Bunny wi… (not verified) on 07 Jul 2017 #permalink

This explains some:
" A small bit of light was shed by [b]Mr Valev[/b] himself in January 2000 in a message to the UK chemical education news group:
'I am not an educator not even a scientist.' "

But I'm guessing this was already obvious.

@Entropic man #5

Unjustified assumptions, no deduction from Einstein's 1905 postulates. This abuse of logic was started by Einstein in 1905:

Albert Einstein, On the Electrodynamics of Moving Bodies, 1905: "From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by tv^2/2c^2 (up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B."

The conclusion

"The clock moved from A to B lags behind the other which has remained at B"

does not follow from Einstein's 1905 postulates - the argument is INVALID. The following two conclusions, in contrast, VALIDLY follow from the postulates:

Conclusion 1: The clock moved from A to B lags behind the other which has remained at B, as judged from the stationary system.

Conclusion 2: The clock which has remained at B lags behind the clock moved from A to B, as judged from the moving system.

Conclusions 1 and 2 (symmetrical time dilation) in their combination give no prediction for the readings of the two clocks as they meet at B. In contrast, the INVALIDLY deduced conclusion (asymmetrical time dilation) provides a straightforward prediction - the moving clock is slow, the stationary one is FAST. The famous "travel into the future" is a direct implication - the slowness of the moving clock means that its (moving) owner can remain virtually unchanged while sixty million years are passing for the stationary system:

Thibault Damour: "The paradigm of the special relativistic upheaval of the usual concept of time is the twin paradox. Let us emphasize that this striking example of time dilation proves that time travel (towards the future) is possible. As a gedanken experiment (if we neglect practicalities such as the technology needed for reaching velocities comparable to the velocity of light, the cost of the fuel and the capacity of the traveller to sustain high accelerations), it shows that a sentient being can jump, "within a minute" (of his experienced time) arbitrarily far in the future, say sixty million years ahead, and see, and be part of, what (will) happen then on Earth. This is a clear way of realizing that the future "already exists" (as we can experience it "in a minute")."

The year 1905 can be regarded as the year of the death of physics. Science died and idiotic ideology was born:

Peter Woit: "I think the worst thing that has happened to theoretical physics over the past 25 years is this descent into ideology, something that has accelerated with the multiverse mania of the last 10-15 years."

Correct, except for the number 25 - it should be replaced by 112.

By Pentcho Valev (not verified) on 07 Jul 2017 #permalink

I don't understand this bit at the end of the article:

This doesn’t necessarily mean that your tether will snap; it more likely means that the rushing ride towards the singularity will pull your entire ship in.

Why wouldn't it snap? The atoms of the rope are held together by electromagnetic forces. If the atoms that are inside the event horizon can't emit any virtual photons outward anymore, then what keeps the rope connected enough to slurp it in?

My guess is the virtual photons of the atoms outside the event horizon still maintaining the connection with those inside. It's one-directional, so to speak, but I suppose that's enough?

By Naked Bunny wi… (not verified) on 07 Jul 2017 #permalink

The article describes that the gluons inside a neutron trying to move from the quark nearest to the singularity cannot reach each the other quarks because that would require traveling faster than the speed of light. If we assume gravity to be a quantum field, then wouldn't the same reasoning apply to gravitons and would the singularity not be able to pull in more mass by exchanging gravitons?

This doesn’t necessarily mean that your tether will snap; it more likely means that the rushing ride towards the singularity will pull your entire ship in.

Ethan, I think it's exactly the opposite . In order for the tethered object to exert any force on the tether outside of the BH, it would have to be exchanging photons "up" the tether. It can't do that. Because of the effect of the event horizon, you must get a clean, forceless separation right at the event horizon. So long as something is pulling "up" on the tether with enough force to escape the BH's gravity, the BH will function as the ultimate knife through butter - slicing apart any tether or other matter at the event horizon, regardless of whether it's held together by the strong, weak, or electromagnetic force. There can be no "pull" from anything inside the event horizon on anything outside the event horizon, except for the pull of gravity.

I know that many physicists believe today that infinities are a sign of breaking of a physical theory. I think the same. So I don't think BHs have a singularity in their center so that means they must be made of some kind of particle. And I think there is only one particle that fits the bill (and it does perfectly). It is a hypothetical particle called Planck particle. Its Wikipedia page was saying it already naturally shows up in physical equations/calculations.

Also I think BHs must be in some kind of fluid state, similar to Neutron stars.

For example, I remember reading complex numbers were showing up in solutions of polynomial equations long before they discovered.

Extreme speculation mode:
I know complex numbers are extremely useful in physics.
It could be said complex numbers are more powerful by being 2D, instead of 1D.
I think if universe is some kind of cellular automata (computer) operating in Planck scale,
it is quite possible its calculations done using quaternions(4D), octonions(8D), maybe even sedenions (16D).

Please contact me. I have questions that i cannot answer on my own

By Christopher Dunn (not verified) on 07 Jul 2017 #permalink

Please contact me, i will get the notify...

By Christopher Dunn (not verified) on 07 Jul 2017 #permalink

Also if there are singularities in the centers of BHs, how it is possible singularities (objects of zero size) can be different from each other to create different sizes of BHs around them?
Or should be really accept properties like mass/energy is just an absolutely abstract number so that an object of zero size can contain them (just as pure information) no problem?

Basing a theoretical gravitational phenomena on a size-less abstract entity is literally an exercise in futility.
If you have a physical point of zero size or extension, you have no way you can assign mass to it. Pretending that zero is a small number is ridiculous, and incorrect. Density is equal to mass divided by volume. If your volume is zero, you have no way to calculate a density, unless of course you believe you can divide by zero, and in that case you can believe in anything you like, but it won't be physics or mathematically valid. If you wish to claim your mass was infinite (which you would not be able to determine anyhow), how could you divide it by any finite number, much less a zero?
Singularities do not really belong in physics at all. Nor does the term 'infinity', except when used euphemistically. In physics, a physical point has use, but only as a diagrammatic tool or location.

Singularities do not have a size. They do not have the capacity to carry a density, mass, or volume...except in fantasy.


Infinities are not necessarily indicators that a theory breaks down.
They can indicate limits or boundary conditions. In this case the limit is that a massive particle cannot travel at the speed of light.

By Entropic man (not verified) on 07 Jul 2017 #permalink

@Entropic man:
Then my interpretation of meaning of infinity is different than yours.

@Entropic man:
In case what I mean is unclear:
Your viewpoint is yes the theory does not apply in the center of BH but it still applies all around. (Or is it, the theory also apply in the center that is why we must accept the existence of a real singularity?)
But my viewpoint is that the theory breaks in the center and that means. what we think about the structure of BHs must be wrong completely. (Like trying to build a skyscraper on a really bad foundation.)


Infinities can be an indication that a theory is incomplete, not necessarily that it is wrong. It is another limits problem.

Newtonian gravity works well enough to describe and predict the orbits of planets and spacecraft around the solar system. Go outside those field strength limits and it becomes apparent that Newtonian gravity as a theory must be a subset of something more complex.

Similarly the singularity at the centre of a black hole is an indicator that relativity is a subset within a larger theory capable of predicting conditions when density approaches infinity.

I do not regard the infinity which occurs as tau tends to zero as similar to the infinite density of the black hole singularity.

Firstly because it represents a real condition. It can be approached but not reached, just as absolute zero temperature can be approached but not achieved

Secondly because the impossibility of reaching c only applies to massive particles. Massless particles, ie. photons normally travel at the speed of light.

Thus c is a limit to what can be achieved within the constraints of a physical system, not a limit to our understanding of that system.

I hope you see my point. I accept that SOME infinities reflect incomplete understanding of a system. I do not regard this as correct for EVERY infinity.

By Entropic man (not verified) on 09 Jul 2017 #permalink

It sure sounds like the parts of the tether passing through the event horizon would just disintegrate immediately as their force mediating particles take off and spiral into the singularity without stopping on the way to their original destination (even if they are normally virtual particles).

@CFT #18
Ever since Hawking came up with the idea of singularities with "zero volume and infinite mass density" I have been amused by the gullibility of his followers. This is the result of using math without a referent in the "real world" of physic.

Obviously a point is just a nominal locus with no volume to contain anything, but physicists keep chattering about singularities as if they actually exist and "contain" mass.

What is wrong with a black hole just being a ball (with whatever Schwarzschild radius) of extremely dense energy/matter?... from which nothing can escape. If it were that simple what would astrophysicists specializing in black holes do for a living?

By Michael Mooney (not verified) on 12 Jul 2017 #permalink

"What is wrong with a black hole just being a ball (with whatever Schwarzschild radius) of extremely dense energy/matter?"

As explained ad infinitum, 3D particles that make up that 3D ball cannot have molecular bonds in those 3 spatial dimensions when all energy can only go in one direction. You cannot have one particle farther away from the "center" than any other particle when light can't even get away from the center.

By That'sNotHowAn… (not verified) on 12 Jul 2017 #permalink

Michael Mooney

A sphere (planet, star, etc) stops getting smaller when the inward force of gravity is balanced by an outward force.

In a planet that is the resistance of atoms to further compression. In a star it is radiation pressure. In a neutron star it is the repulsion.between neutrons.

What force stops your hypothetical high density ball collapsing into a singularity?

By Entropic man (not verified) on 12 Jul 2017 #permalink

@Entropic man:
"What force stops your hypothetical high density ball collapsing into a singularity?"
That is exactly why I was suggesting BHs must be made of Planck particles.
From Wikipedia about Planck Particle:
"its Compton wavelength and Schwarzschild radius are about the Planck length"
Planck particles are smallest possible particles. Imagine if any particle is compressed in an unstoppable way, its Compton wavelength gets smaller and smaller and finally it is reduced Planck length, where it cannot get any smaller.

I think BHs being made of Planck particles is theoretically possible and it does not lead to any contradictions with neither Quantum Mechanics nor Relativity.
But I am not a physicist and I would like to see Ethan writing a post evaluating this idea. if possible.

That'sNotHowAnyOfThisWorks and Entropic Man,
Please read CFT's #18 and consider the fact that a point has no volume to contain anything. Then consider how Schwarzschild came up with the radius of various BALLS of extremely dense matter, gravity wells from which nothing can escape.

"You cannot have one particle farther away from the “center” than any other particle when light can’t even get away from the center."
Light can't escape a black hole, regardless of its radius, but a point doesn't have a radius. Consider the event horizon as the surface of the bh sphere.

"What force stops your hypothetical high density ball collapsing into a singularity?"
Again... the fact that a "singularity" is just an imaginary point, not a volume as required to contain compressed matter. Whatever the density, a black hole is still a ball of a given radius.

By Michael Mooney (not verified) on 13 Jul 2017 #permalink

"Then consider how Schwarzschild came up with the radius of various BALLS of extremely dense matter, gravity wells from which nothing can escape."

No, that isn't what his radius represents. It is purely a mathematical representation. The mathematical radius where a given mass becomes a black hole. It does not stipulate, nor does it follow from the computation itself, that the black hole that results must be a sphere with that radius. That's not how that works.

By That'sNotHowAn… (not verified) on 13 Jul 2017 #permalink

..........Works: "No, that isn’t what his radius represents. It is purely a mathematical representation."
So you don't know that a radius is the distance from the center of a circle or sphere to the circle's perimeter or the sphere/ball's surface.
"Pure math" means nothing until it is applied to "the world" of actual things/ phenomena. And again, a point has no radius or volume and can't contain anything.

By Michael Mooney (not verified) on 14 Jul 2017 #permalink

edit: ... circle's circumference...

By Michael Mooney (not verified) on 14 Jul 2017 #permalink

^^^^^ That's funny stuff right there.

By That'sNotHowAn… (not verified) on 14 Jul 2017 #permalink


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By Elle H.C. (not verified) on 15 Jul 2017 #permalink

I am having the same problem with both Firefox and Chrome.
"Exceeded the maximum global requests per minute for crawlers or humans."
I am guessing the servers having a really busy day maybe?

me as well

By Sinisa Lazarek (not verified) on 15 Jul 2017 #permalink

It' s a security program that sometimes doesn't play well with certain server caches. Certain specific caches end up caching and serving up the message even if the security program is uninstalled. The hosting outfit likely has to clear their server cache.

My access has been cut off too. I presumed I was banned and unsubscribed. Was that premature? Ethan invited relativity critics to say what it would take to address our criticism. My reply was not answered and then I got the error page. Coincidence?

By Michael Mooney (not verified) on 17 Jul 2017 #permalink

@ MM

give it a rest MM.. not everything revolves around you!! What an ego! If you had been banned, you wouldn't bee able to post anything... obviously you can.

Instead try reading what's been posted. PJ and rest have pointed that out. But you must have been obsessed about your relativity issues to not actually read what ethan posted:

"And finally, it looks like there are some problems with a couple of plugins on Scienceblogs: Jetpack (for anyone on the back-end) and Wordfence (for anyone trying to comment). Until the admins get things in order, the best I can recommend is to wait ~10 minutes and try and comment again if you get blocked. "

By Sinisa Lazarek (not verified) on 17 Jul 2017 #permalink