Slashdot Mirror
How Would an Astronaut Falling Into a Black Hole Die?
ananyo writes "According to the accepted account, an astronaut falling into a black hole would be ripped apart, and his remnants crushed as they plunged into the black hole's infinitely dense core. Calculations by Joseph Polchinski, a string theorist at the Kavli Institute for Theoretical Physics in Santa Barbara, California, though, point to a different end: quantum effects turn the event horizon into a seething maelstrom of particles and anyone who fell in would hit a wall of fire and be burned to a crisp in an instant. There's one problem with the firewall theory. If Polchinski is right, then either general relativity or quantum mechanics is wrong and his work has triggered a mini-crisis in theoretical physics."
Locate a black hole and start shooting monkeys at it! "Science can not progress without heaps [of monkeys]"
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
The /. I knew and loved a decade ago is gone.
Hell is in the black hole. And pray you don't go there with a psychotic red robot.
TFA is an interesting article about a physicist apparently discovering an inherent contradiction between general relativity and quantum mechanics. The "black hole" stuff is really just the context that led to the apparent contradiction: the real issue is much deeper than that. It's depressing that the real underlying hypothesis isn't considered newsworthy, and the editor feels the need to lead with the "black hole" stuff.
[Sir Garlon] is the marvellest knight that is now living, for he destroyeth many good knights, for he goeth invisible.
Have gnu, will travel.
Unicorns would stampede the astronaut as he enters the event horizon. There's one problem with the unicorn theory. If I'm right, then either general relativity or quantum mechanics is wrong.
Heck, considering what we know about the environments around black holes, not only will the gravitational tides kill you before you reach the event horizon, so will the radiation.
Everybody repeat after me: "Black holes ain't yer friend. Don't try to hug them, you will die."
try to avoid falling into a black hole
JADBP
well, technically, wouldn't the convicted murder BECOME an astronaut by definition the moment we shot him into space?
slashdot is really provoking the deep questions today.
i could live a little longer in this prison
The other way around: The universe dies of old age around the astronaut and black hole.
I thought that black holes were still theoretical. Or have they been scientifically proved, and I'm just an asshat?
They've been observed - just because there's theoretical work being done about something doesn't mean it hasn't been shown to exist.
Leave your crappy sitcom references at the door and let the adults talk.
Take the time to read too, you might learn something that isn't some comic book fantasy.
Besides, if anyone knows the answer, it's Dr. Hans Reinhardt.
This isn't true.
QM and *special* relativity get along just fine. When you combine them in a simple way you get predictions like antimatter, the fine structure of the hydrogen atom, and so on. If you do this in a more detailed way, using quantum field theory, you get the fantastically accurate predictions of quantum electrodynamics, the theory of quantum chromodynamics that can't be solved with pen and paper but which still gives accurate predictions when done on supercomputers, and so forth.
And there's nothing forbidding QM from playing nice with general relativity, either; we just don't know how it works yet. There are some models, like lattice quantum gravity, that seem quite promising.
How would he die?
Of old age, on the multimillion year journey to the nearest black hole, I suppose.
But don't let me be the one to interrupt your little rec time, on the holodeck. ;-)
"Flyin' in just a sweet place,
Never been known to fail..."
If the astronaut gets across the event horizon, then he will never die relative to us. So, there really isn't a problem here as far as I can tell.
Umm... He's a string theorist, so...
Listen to Zombie Feynman kids: Unscientific:
It must have been something you assimilated. . . .
There was an SF short story in which an interstellar alien being was psychically-linked with a human and was helping her team study a black hole. The alien is unable to escape the gravity well and is quickly destroyed. Unfortunately, for the human, the alien's time frame is different, so the human will experience its psychic scream for her entire life.
Heck, considering what we know about the locations of black holes and the speed of manmade spacefcraft, old age will probably kill you before you get close enough to notice the gravity.
Everybody repeat after me: "Space is big. Don't mind Sarten-X, he is a jackass."
You do not have a moral or legal right to do absolutely anything you want.
They've found numerous stellar objects of various sizes that conform to the preditions of black holes. (Mass, diameter, etc) Though none have been directly observed, their 'feeding' does generate a lot of energy that is detected when something falls in. Just recently one that had been relatively quiet for some time gave of a nice 'burp' of radiation as it apparently 'ate' a planet.
:D
Have we been to a black hole? No.
Have we taken photos of an actual black hole? No.
Have we seen gravitational effects that look exactly like what a black hole should have? Yes.
Do those gravitational effects calculate out as something of several to millions of solar masses in a tiny volume that can't exist in any non-black hole way that we are aware of? Yes.
Have we seen the radiation from an accretion disk falling into and being destroyed by a black hole as predicted? Yes.
Is a black hole what astrophysicists think it is? Probably.
Is a black hole what non-scientists (hollywood, general public, dentists, etc) think it is? Probably not.
Do you really exist? This is about black holes, but your existence is only a bit less theoretical than that of a black holes, though some of the specifics of either may not be what is generally thought about them.
And no, a black hole is not god dividing by zero. It's more likely an alien mad scientist multiplying by the square root of negative zero.
Actually, it is also possible that there is no such thing as a black hole - but cetain parts of the universe just suck. I have known some towns like that.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
He would die of shock [...] And then her body would be torn asunder.
So you think a black hole would accomplish a gender change on the subject? Interesting theory.
While yes, one of the things you would have to deal with is the incredibly hot material swirling around the event horizon which, in and of itself, should produce enough X-rays to fry you, I think this article is actually talking more about an actual characteristic of the event horizon, as opposed to what is in orbit around it, or even what is infalling.
In short, space is supposed to look the same to an observer no matter what side of the event horizon they are on. Instead, a special condition where you smack into something that is there beyond what you would expect from a black hole with infalling matter occurs. That "wall of fire" obviously consists of stuff that has entered the event horizon of the black hole, but it is structured in such a way as to form a highly energetic barrier that should not be there based on our current understanding of relativity or quantum mechanics.
This reminds me of the two unknowns: how can a black hole be created if the matter falling to it can never get there? The another one is of course: how can gravitons escape event horizon and attract anything?
I think good theorists can answer both - I cannot either.
That was when Slashdot IDs were negative numbers. Ahhh... I was so much older then, I'm younger than that now.
First answer: Alone.
But I saw this rather interesting video of a lecture by Leonard Susskind : http://www.youtube.com/watch?v=pf0D8A0jRiY ;)
It will probably not answer your question, but it's about black holes and they're very cool! Or hot. Depending on the observer
Privacy is terrorism.
The whole "what would happen to an astronaut"
...is part of a collection of classic thought experiments by real scientists which predate the internet. Your concerns are misplaced.
Don't worry, I can fix that...
Now, Wikipedia says "In addition, a convicted murderer shot through space toward a black hole for experimental purposes."
"astronaut" - Someone on who has gone into space.
"fall" - 'to descend under the force of gravity"
"Into" - "to the inside of"; Also "toward or in the direction of:"
"black hole" - "an object in space so dense that its escape velocity exceeds the speed of light"
"die" - "to cease to live; undergo the complete and permanent cessation of all vital functions; become dead."
Or possible in this case: "to cease to exist" literally.
"Ass" - You.
The Kruger Dunning explains most post on
And there's nothing forbidding QM from playing nice with general relativity, either; we just don't know how it works yet.
Translation: As currently formulated, at least one of quantum mechanics and general relativity is wrong, although like Newtonian mechanics or pre-relativistic optics, they will undoubtedly continue to be practical and very accurate approximations.
We knew this as soon as quantum mechanics was developed.
The idea is that the two particles form, and one is closer to the black hole than the other. One of them barely falls in, while the other barely makes it out. No difference in how gravity effects them, just a difference in initial positions.
Then why would the particle be affected differently than the antiparticle? Why wouldn't *both* fall into the black hole equally?
Both the particle and the antiparticle are affected equally by gravity, but gravity is the weakest force in nature. Think about it: a simple chair, held together by the electromagnetic force, supports you above the ground by counteracting the gravitational attraction of the entire Earth pulling you down.
Since virtual particle pairs start from vacuum, they are always created with equal but opposite momentum. This momentum can't be very big because the attraction between the pair (usually electromagnetic) has to be strong enough to quickly counteract that initial momentum (and bring the particles back together fast enough for them to still count as "virtual"). But just because the momentum can't be very big doesn't mean it can't be big enough for one particle to escape a black hole, if the particles happen to pop into existence with one of them pointing in just the right direction to escape. Hawking predicts that the odds are 50/50 on whether it's the matter particle or the antimatter particle that does the escaping; it has nothing to do with the particles responding differently to gravity.
(Keep in mind that the escaping particle doesn't have to rocket out in a straight line at escape velocity. Instead, it can take a few swings around the black hole in a rapidly decaying orbit, until it slingshots out on a hyperbolic path. The smaller the black hole gets, the more definite the position is for every matter/antimatter particle pair, and by Heisenberg's uncertainty principle applied to position-momentum, this makes it easier for one of the two particles to escape. A smaller black hole also has the bonus that, looking out from just above the event horizon, more directions point away from the black hole, giving more chances to escape.)
You could actually make a black hole that radiates away Hawking radiation with a bias toward antimatter over matter, or vice versa. It's easy: black holes can have an electric charge, so just electrically charge the black hole! Like charges repel, so if the black hole is positively charged, it will preferentially eject positrons instead of electrons. However, the absorbed electrons neutralize the black hole's electric charge, bringing it back to neutral and making the Hawking radiation return to a 50/50 ratio between matter and antimatter.
(We suspect that the universe has a small preference for matter over antimatter, and this is why the universe is made of matter. But this mostly happens for some heavy uncharged mesons, not for lightweight simple particles like electrons. Here, "heavy" means "high energy" means "unlikely to appear in Hawking radiation". So the radiation may not strictly be 50/50, but it should be very close.)
Range Voting: preference intensity matters
Assuming you're not trolling, that's a nice story, but that's not how science works.
The trouble is that "what we know about black holes" is all theoretical and mathematical.
Usually, the first step in science is to observe something. In the case of black holes, our knowledge of their existence can be traced back to a few experiments, which provided pretty solid evidence against the prevailing theories of aether. The observation that doesn't match the expectation means that the theories aren't right, and must be changed.
In fact, many of today's experiments are simply re-running old trials, but with more precise technology. Rather than dropping rocks off a tower, we can measure how fast individual atoms fall, giving us a more exact understanding of gravity. Usually the results are a perfect match for what's expected, but sometimes they aren't.
Black holes were invented to explain present-day theories about the motion of stars and galaxies.
Next comes the theory. Starting from the results of those experiments, Einstein hypothesized his theories of relativity, which are really little more than a collection of relationships derived from the assumption that the speed of light in a vacuum is constant. His theories explained the results of previous experiments, and importantly, provided a set of formulas that can be used to make predictions for future experiments.
Mathematics are very useful in describing measured experiments and observations in the physical universe. As soon as mathematics and computer simulations go beyond what is actually observed and measured, it no longer describes the real world were living in.
The relationships in the physical world are described with mathematics. Sometimes, when math is insufficient to easily describe a particular relationship, new mathematical forms are invented to accommodate the real world. Ultimately, though, every physicist knows that the mathematical models do not prescribe reality, but describe our understanding of it. Again, we use those models to predict the outcome of future experiments.
At the center of these hypothetical, theoretical black holes is this mathematical entity that has been called a "singularity". This is another mathematical fiction that can't exist in the known universe.
That depends on the rules of the known universe. in 1915, Karl Schwarzchild transformed Einstein's theories of relativity into a form that would require black holes. This means that Einstein's formulas can only be correct if the universe allows black holes. If the universe does not allow black holes, then Einsteins formulas must be wrong - though less wrong than the aether theory they replaced.
Perhaps it is time to examine some of these widely held theories that require these mathematical fictions.
That's what experiments are for.
No one has ever directly observed a black hole and thereby shown that these things even exist in the real world.
Black holes have been observed many times.
In 1929 an astronomer named Edwin Hubble discovered that "red shift" of distant galaxies. Then he made the assumption (belief, faith) about the cau
You do not have a moral or legal right to do absolutely anything you want.
All so-called "discoveries" of black holes are attributed to their supposedly enormous gravitational effects on their surroundings, but they never themselves have been found. The same is true of dark matter. The link you gave is all about how the gravity supposedly affects the surroundings of a black hole.
http://www.cfa.harvard.edu/seuforum/bh_reallyexist.htm
ALL the observations in that article can be explained by the operation of a force 36 orders of magnitude greater than gravity. This force is electromagnetism as evidenced by cosmic plasmas that can be accurately modeled not only with computers, but with real physical experiments in the lab. Most of the universe is not nicely electrically neutral, like here on earth, but consists of highly charged electrically active plasma. Most atoms in the universe don't have all their electrons nice and neatly orbiting their nuclei.
Scientists are observing immensely powerful cosmic rays and other radiation from many sources in the universe. All this radiation involves the electric force and has nothing to do with gravity. Scientists have postulated that there should be gravity waves and have spent gobs of money to try and detect these, but so far that has been money wasted since they have not found such waves. In addition, there are measurements of immense magnetic fields in space and on the sun. It is a firmly established principle of science, that magnetic fields can be generated easily by the motion of electric charges.
The large-scale universe is controlled by electrical forces that are far greater than gravity. Gravity is only a controlling factor in electrically neutral environments such as we have here in our corner of the universe. Even if only one atom in 100 billion loses one of its electrons, the force generated by this tiny charge imbalance is far greater than the gravity generated by those 100 billion atoms. You can verify that by doing an experiment right in your own home. Just pick up a few bits of Styrofoam with a charged glass or plastic rod. Charge the rod by rubbing it with a silk cloth. The electric charge on the glass rod will easily overcome the gravity generated by the entire Earth.
A sufficiently advanced simulation is indistinguishable from reality.