What Would We Experience If Earth Spontaneously Turned Into A Black Hole? (medium.com) 126
Ethan Siegel, writing at Medium's Starts with a Bang: Either way, the first thing that would happen would be a transition from being at rest -- where the force from the atoms on Earth's surface pushed back on us with an equal and opposite force to gravitational acceleration -- to being in free-fall: at 9.8 m/s2 (32 feet/s2), towards the center of the Earth. Unlike most free-fall scenarios we experience on Earth today, such as a skydiver experiences when jumping out of an airplane, you'd have an eerie, lasting experience. You wouldn't feel the wind rushing past you, but rather the air would accelerate down towards the center of the Earth exactly at the same rate you did. There would be no drag forces on you, and you would never reach a maximum speed: a terminal velocity. You'd simply fall faster and faster as time progressed.
That "rising stomach" sensation that you'd feel -- like you get at the top of a drop on a roller coaster -- would begin as soon as free-fall started, but would continue unabated. You'd experience total weightlessness, like an astronaut on the International Space Station, and would be unable to "feel" how fast you were falling. Which is a good thing, because not only would you fall faster and faster towards the Earth's center as time went on, but your acceleration would actually increase as you got closer to that central singularity.
That "rising stomach" sensation that you'd feel -- like you get at the top of a drop on a roller coaster -- would begin as soon as free-fall started, but would continue unabated. You'd experience total weightlessness, like an astronaut on the International Space Station, and would be unable to "feel" how fast you were falling. Which is a good thing, because not only would you fall faster and faster towards the Earth's center as time went on, but your acceleration would actually increase as you got closer to that central singularity.
Not a good time for such hypotheticals (Score:5, Insightful)
Please don't post such stories in 2020 and just after an overly-close contentious election.
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Not to mention that this question is more appropriate for a What If... from XKCD. In any case, the writer is incorrect on the most basic speculation. If the entire Earth's mass suddenly became a point in the center, it would be be 3958 miles, give or take, from the people on the former surface. Consider that, at 3958 miles above the surface of the Earth, acceleration due to gravity is only about 2.45 m/s^2. So, it will be similar if the Earth suddenly became a point mass at the center.
Also, the air wouldn't
Re:Not a good time for such hypotheticals (Score:5, Informative)
Eh? Unless I'm misremembering my physics, for the purposes of calculating gravity the distance is calculated from the center of mass. Not the surface. Instead of being 3958 miles from the center of the earth, we'd be 3958 from the center of a black hole of equal mass.
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You're right. I've got to stop posting too quickly without doing the actual math. You get further from the near side of Earth but closer to the far side and it all evens out. Ugh. Apologies. I've made this same mistake before and somehow I seem to keep messing it up.
Of course, the rest of it still happens about the same way I described, the atmosphere just doesn't expand as much at the start. It still doesn't freefall towards the center though, The faster molecules still rocket into the vacuum at the center
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Yeah. That makes sense. The atmosphere would get you long before tidal forces would, I should think. Still, I'd imagine you'd have a minute or two of freefall to ponder your life choices before things got unsurvivable. (Either from rapidly changing pressure and temperature or just getting smacked with some flying debris.)
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Life choices like: why did I choose to live on a divide by zero error in the universe?
Incidentally, "I made poor life choices!" is exactly what I scream at the top of roller coasters.
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Or in terms of normal literary use as implied, a black hole the size of the earth and hence, what would you feel if that happened. Taking into account relative acceleration at that proximity, your nerves would break up into their constituent subatomic elements faster than you could ever possibly feel it happening. You would feel nothing, at a normal space level, but at a quantum conscious level, you would note the loss of your normal space body and go on to do what ever unbound quantum consciousness does. D
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I messed up. The acceleration would still be normal, to start. Sorry.
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Basically the problem I have is that clearly when you're on the surface of a planet, the matter nearest to you is what attracts you the most, whereas the matter on the other side of the planet attracts you the least. So, the trap I fell into, and that I fell into here is thinking that the density distribution therefore matters and you can't think of a volume as being the same as a point source. That is true, but only up to a certain point. The reality is, on a planet, any significant variation in density is
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If you replace the earth by a black hole with the same mass and you just keep the thin shell at the surface then in principle the pull of the earth stays exactly the same and you wouldn't notice the difference. Obviously there would be some stability problems. David Brin wrote a book about a small black hole which was accidentally released into the earth. As it eats the earth it does not increase gravity, but it does increase instability and causes earthquakes which increase in size. Such things do not end
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Yep, I messed up on that part.
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No, gravitational acceleration is determined by the distance between the centers of mass, the distance to the surface is irrelevant unless you're actually beneath it. g = G(M/r^2), r is radius from the center of mass, not distance to the surface.
Since gravity at all points above the previous surface would remain unchanged, air would (initially) fall alongside you - however, as you fell the volume of the spherical shell of air that had been near the surface would rapidly shrink - by the time you fell 10% of
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It's also worth noting the the event horizon of an Earth-mass black hole would be only 17mm across, so the trickle of hot gas falling into it would be quite slow, and most of the gas cloud might remain in orbit for centuries.
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Hard to measure how fast it would enter the even horizon. It wouldn't be like at the center of the Earth, where gravity is in balance from all of the other surrounding mass. The atmosphere would be under incredible pressure and hyper-compressed and superheated.
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True, but you're also no longer talking about material being held up by the material beneath it - it's now a cloud of orbitting gas , and only material ejected from the cloud will be able to collide with the black hole at it's center.
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Not sure about this. It's a cloud of very dense gas/plasma. It's not going to act like loose orbiting rocks. There will be constant collisions between the atoms, not to mention powerful magnetic fields. All of that will cause pressure that will push particles into the center.
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Maybe - or it may form a dense ring with very little ever reaching the black hole. I certainly don't have the expertise to offer an informed opinion - I just know that accretion disks seem to be far more common around black holes than big clouds of gas.
My guess is that it would initially resemble a very small synestia, but that's pure intuition in a field outside my expertise. Possibly worth two grains of salt, but probably not a spoonful.
Also, where would those magnetic fields come from? They can't come
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My understanding was that black holes were supposed to have magnetic fields, but I'm not really sure of the mechanism either. As for the accretion disk, I thought that would be a more of a later stage thing with the disk being made up of the material that was on the right trajectory early on to end up in orbit rather than ejected or sucked in early on. Atmosphere at the equator will be spinning around the black hole and should accelerate into a faster spin as it collapses inwards. Atmosphere at the poles m
Black hole math (Score:2)
There's no known natural way to form such a small black hole from normal matter, however primordial black holes formed in the first moments of the universe could be any size.
It should also be possible to create an artificial black hole of arbitrary size by concentrating enough energy into a small enough volume, traditionally classical EM radiation was used, though a Bose-Einstein condensate might be easier (I really don't know QM or relativity well enough to say anything conclusively). Since bosons aren't
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The question that raises for me is what level of radiation output an earth mass black hole that instantaneously forms would be putting out. Would it be able to fry people on the former surface by shear output, or would it be mild. Then there's the question of the makeup of the radiation. Would it be harmless, or deadly, and how quickly? So many questions about what would actually happen here, but they all basically boil down to the question of what would kill everyone first
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Ironically, it's only truly tiny black holes that produce much Hawking radiation.
The calculator says a 1 Earth-mass black hole would have an effective temperature of 0.02 K, and emits a total of 10^-19 W with a peak photon frequency of 1.7GHz. So no, not remotely a problem - a 4G phone puts out insanely more radiation, and at a higher frequency.
In fact, to climb to all of one watt of radiation you've got to reduce the mass to 3-billionths of an Earth mass. It would then have a peak frequency of 530,000 THz,
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So the flash-frying waits until the crunch of the atmosphere cycling inwards. So, asphyxiation/freezing in short order for the majority, followed by flash frying shortly after for anyone who happens to be wearing an insulated pressure suit at the time (provided they're not killed by collisions with other people/objects).
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Oh, this is much better than I was able to do. From my (admittedly rusty) post-it note math, it would take about 800 seconds to fall from the former surface of the Earth to the new black hole, but I forgot about the rotation.
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Not bad. You might find this orbital calculator (and others) interesting - I just found it when replying to a comment above, and foresee using it many times in the future. https://www.omnicalculator.com... [omnicalculator.com]
Anyway, I misremembered equatorial speed (460m/s = 1000mph), and with corrected numbers the calculator says a pebble sitting on the erstwhile equator would take about 900 seconds to fall to a minimum altitude of 6.7miles , where it would be whipping around the black hole at a speed of 168 miles per seco
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Yep. Sorry, messed that up. Mea Culpa. Didn't think that part all the way through. The violent, swirling plasma that the atmosphere would turn into is still the logical outcome though.
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I'm not sure about plasma, but certainly hot. Even if it did become a plasma for a while, it would cool off fairly rapidly as heat was radiated away into space. Unless the black hole was "eating" fast enough for the radiation to keep the gas superheated.
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It would definitely last long enough that all of people (corpses) falling towards the center would be completely vaporized early on.
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No argument there - except I'm not not sure it would actually be a plasma. There's a reason plasma is considered a different state of matter - it's more than just a really hot gas, it also has to be subjected to a powerful magnetic field to split it into ionized gas and free-flowing electrons.
Black holes can't generate magnetic fields themselves (that would be information escaping the event horizon), and we don't have a good understanding of how they're generated around them.
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I assumed there would be an extremely powerful magnetic field close to the black hole from the concentration of the Earth's original magnetic field and that the superheated gases would end up rotating rapidly through that field. I'm not really all that sure though. Would the magnetic field just go dead? Now I'm thinking about what would happen to the free electons in a plasma in contact with the event horizon of a tiny black hole. Obviously, atoms would be sucked into the black hole, but so would electrons
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I think it's believed that the only properties a black hole has are mass, speed, angular momentum (expressed as frame dragging), and electrostatic charge. Everything else would depend on the internal state of the black hole, and thus require transmitting information from inside the event horizon, which can't happen.
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at the equator you're traveling 400mph eastward with the surface of the Earth, which if not for the air would put you in an elliptical orbit around the black hole, which would repeatedly bring you back to your initial 3958 miles from the center at every perigee.
Using your given radius, at the equator you're traveling at about (24,869 mi circumference/24 hrs) ~= 1040 mph. You'll accelerate as you fall, but still won't reach anywhere near the speed needed to achieve an orbit.
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Okay, I was wrong in my math - you still won't reach orbital velocity when falling, but you'll get close at 9.8 m/s^2 for 800 seconds or so. So, you'll go around a few times, but still won't be in a true orbit.
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Sure you will. Plug in the numbers https://www.omnicalculator.com... [omnicalculator.com]
A pebble sitting on the erstwhile equator would take about 900 seconds to fall to a minimum altitude of 6.7miles , where it would whip around the black hole at a speed of 168 miles per second.
Remember too, you won't be falling at 9.8m/s except for the first few moments - gravitational acceleration increases as 1/r^2 - each time you halve your distance to the center, you increase your acceleration by a factor of 4
Yeah black holes suck as much as 2020 (Score:3)
That would be about the only way 2020 could suck more.
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Please don't post such stories in 2020 and just after an overly-close contentious election.
I for one am glad to find out that the "rising stomach" sensation I've been feeling lately was due to gravitational collapse and not Donald Trump.
BHM...? (Score:5, Funny)
Re:BHM...? (Score:5, Funny)
"Black Holes Matter?"
If you spend any amount of time in bing.com video search with their version of safe search disabled, you will quickly learn that ALL holes matter. Even with search terms you would never expect, the internet finds a way.
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[as Jeff Goldblum]
The internet... finds a way...
gravity (Score:2)
At what point would the tidal forces rip you in two and how long would you get to enjoy this part?
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At what point would the tidal forces rip you in two and how long would you get to enjoy this part?
Two? I'm pretty sure there would be many more than two parts...
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More like they would stretch you into a piece of meat-spaghetti.
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No need to worry about tidal forces ripping you in two. You would be dead and completely vaporized before that could happen.
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Except you've got 60 miles of atmosphere above you - if there's a downwards wind (I'm unconvinced) you would be blown downwards along with it and rapidly match speed.
The Earth rotates relatively slowly, and at ~18mm even a few mm more or less in one plane isn't going to make a whole lot of difference to the giant swirling cloud of gas around it. And I suspect even the solid objects would rapidly become superheated gas as the atmosphere collapsed to a much smaller volume under much greater gravity. Eventua
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Re: gravity (Score:2)
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Atmospheric pressure is not particularly high, so if we assume that everything below the immediate surface of the earth (do we include buildings?) spontaneously transformed into a black hole of the same mass and center, you'd get a violent downdraft of rapidly expanding atmopshere
A spherically-symmetric mass exhibits the same gravitational force above it regardless of how concentrated it is - from a uniform mass to a tiny clump at the center. This is true regardless of whether the tight clump is inside an
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LSD (Score:2)
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So, dude, are there any laws against voting high? Inquiring for a friend.
Nope. (Shouldn't be, either: If you'd fight a civil war, or decide to enlist in one, while high, you should decide about what vote to cast while in the same state. Elections are about modelling civil wars sufficiently well to convince the losers of the election to not bother trying the war.)
Also: Restrictions on voting (other than whether you're eligible and only voting once) are suspect - because they have historically been used b
Re: LSD (Score:2)
Winners arenâ(TM)t Losers. I donâ(TM)t like losers.
instant death from intense radiation (Score:4, Informative)
Well if you go that close to a black hole you'd already be dead. And if you were far away you'd not actually feel anything at all. That's what the theory of relativity says. You cannot sense any graity field inwhich you are orbiting or frefalling in. Period. So you would not feel yourself in elevator like free fall at all. The exception to this rule is when you, as a quasi rigid body, have a length dimension that is long compared to the gradient of the gravity field distortion. Then you can notice you are being ripped in two by differential acceleration. This still would not manifest as a feeling of free fall. It would be like being put on a Rack instead. But before you reached that steep gradient region you would have been fried by the radiation emission which is much longer in range.
That feeling is no gravity (Score:2)
> You cannot sense any graity field inwhich you are orbiting or frefalling in. Period. So you would not feel yourself in elevator like free fall at all.
I wonder if it occurred to you that your argument implies you can't feel "elevator like free fall" in Earth's normal gravity? You've essentially said that feeling doesn't exist.
If you can't sense free-fall under ANY gravity field, you can't sense free-fall under normal Earth gravity. So clearly that's false.
I believe the resolution to that is that we ar
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> You cannot sense any graity field inwhich you are orbiting or frefalling in. Period. So you would not feel yourself in elevator like free fall at all.
I wonder if it occurred to you that your argument implies you can't feel "elevator like free fall" in Earth's normal gravity? You've essentially said that feeling doesn't exist.
If you can't sense free-fall under ANY gravity field, you can't sense free-fall under normal Earth gravity. So clearly that's false.
I believe the resolution to that is that we are accustomed to feeling 1G. In free fall, that 1G goes to zero. We feel that stomach rising feeling when we go from 1G to zero, when we fall.
I think it would be accurate to say:
In free fall, one cannot internally sense the magnitude of the gravity under which one is falling; only that you *are* falling (experiencing zero internal G).
One can, of course, look externally and notice you are approaching the ground quite quickly.
I don't disagree with your reasoning except that you inverted one key thing. There is no gravity. THere is instead a floor pushing up. That is we don't ever feel gravity. We only feel things blocking the path of our acceleration.
When an elevator descends it reduces the blockage of the acceleration.
if the earth were to get smaller but left you at the same radius, it's not longer blocking your acceleration.
The difference is this. The florce blockage is applied from your feet and then successively from on
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Well, keep in mind that this theoretical black hole only has the mass of one Earth, meaning it would be close to the size of a small marble. You'd have to fall for quite a few hundred miles at relatively low acceleration before you'd get close enough to experience spaghettification. That also assumes you're at rest at the start of your fall, and not still orbiting at close to 1,000 MPH due to the rotation of the Earth. Also, this assumes that a black hole can even sustain itself at that mass. I'm not a
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that's incorrect. your stomach and you will "fall" together. and you are not "falling" or even being accelerated at all. Gravity is not a force, it's a distortion of space. Einstein's opinions, not mine. You cannot tell you are falling if everything around you is falling too.
Here's what they really are trying to describe. They are really saying what if the earth suddenly got smaller but you were left levitating above it. Forget the black hole part as that's not germane. In that case, what you experi
Re: instant death from intense radiation (Score:2)
But without the surface the atmosphere would rapidly expand to fill the void left by the absence of the planet so you'd also feel the air rushing past you. And be propelled by it to a certain degree, lessening over time as it became less dense. But would probably pass out due to lack of oxygen within a few minutes regardless
What would a physicist feel? (Score:4, Funny)
A certain unease that everything that was understood about general relativity and energy were in fact wrong.
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True, but I would take solace in the fact that that would no longer be a concern of mine in a few minutes.
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the election count would be over.
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We wouldn't have time the inevitable recounts, either.
Probably nothing (Score:5, Informative)
Death would be instantaneous. Because whatever process that collapsed the Earth into a singularity would not differentiate between the rocks, oceans, trees and the other little bits of biological material stuck to the surface commonly known as people.
Energy (Score:2)
Probably right. The amount of mass and energy needed to create a black hole in the first place would obliterate the earth in a fraction of a second.
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They will converge and stuff will soon crush you from the sides (if the air pressure increase does not get you first) but that is not instantaneous.
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And if a black hole magically appeared at the center of the earth, either you are outside the Schwartchild radius and you get get crush
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You are correct that the Earth cannot spontaneously turn into a black hole. This article appears to be more of a what-if thought-experiment.
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Since there's no known mechanism by which the Earth could be suddenly turned into a black hole, I think it's safe to say the process would be magic. And once we invoke magic, there's no reason to assume it couldn't tell the difference between rock and living things.
Medium (Score:5, Interesting)
The only thing I really want to know is what timezone (of the proposed 10 minute increments) the Medium writers would recommend as we fall.
Seriously can we get Medium blacklisted from Slashdot? It reminds me of years ago where every other day Slashdot posted one of those god awful "science" stories from Forbes.
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Medium is for morons. Everything posted there is garbage.
Medium is essentially just a blog platform that anyone can post to. (I guess, I haven't tried to create an account, but that's what their about page says.) The major "thing" it does differently from any other blogging platform is provide a way for people to pay to read it.
I'm not disagreeing with you or anything, I'm just explaining why.
Define "spontaneously" (Score:2)
The tidal forces will rip us apart (Score:2)
Next question?
At rest (Score:2)
Either way, the first thing that would happen would be a transition from being at rest -- where the force from the atoms on Earth's surface pushed back on us with an equal and opposite force to gravitational acceleration -- to being in free-fall: at 9.8 m/s2 (32 feet/s2), towards the center of the Earth.
Actually, this is a common misconception about gravity.
In the framework of General Relativity, in curved spacetime, you are at rest during free fall.
When standing on the surface, you're actually accelerating upwards (caused by electrostatic repulsion between the ground and you).
Relief (Score:2)
Transmutation (Score:3)
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And if my grandma had wheels... (Score:2)
...she'd be a bicycle.
What is the point of all this? It's not like it's gonna happen any time soon.
How about what if a black hole passed through the solar system and you'd turn so it passes right in the direction where your sexy bits point at? .... Hey, if I die, at least I'm gonna do it with some fun! :D
Cause you can bet that's what I'd do!
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Doing science is hard.
So is communicating it to a lay public. Describing "what if" situations is one method. I think that's what this article attempts.
it depends on how big it is (Score:2)
are we talking about a black hole with the mass of Earth or a black hole the size of Earth? if the latter, it would mean the instant destruction of all life on Earth, the rapid destruction of the solar system, the eventual collapse of this area of the galaxy over many years, and perhaps the disruption of the entire galaxy over thousands of years.
a black hole as big as the Earth suddenly exist would emit quite a substantial gravitational surge. one with the mass of the Earth would do no more in gravity than
Is there some reason we're talking about this? (Score:2)
CERN performing a new experiment, perhaps?
We'll feel some pressure points (Score:2)
Black hole: Omae wa mou shindeiru.
Everybody: NANI???
Realistically (cough, cough) (Score:2)
Actually if 'the earth' refers just to the non human matter & non atmosphere components of the system, the black hole would be very small (about 1" diameter) and the population would converge near the center of mass. As air and the inner group of people contacted the event horizon there would be create a violent plasma outburst which would then consume the rest of us and blow most of our remains away.
Instant death (Score:2)
What Would We Experience If Earth Spontaneously Turned Into A Black Hole?
Instant death. Saved you from having to read the article. You're welcome.
Tangental Velocty (Score:3)
Further, "Uranium is a relatively common element in the crust of the Earth (very much more than in the mantle). It is a metal approximately as common as tin or zinc, and it is a constituent of most rocks and even of the sea." ( from https://www.world-nuclear.org/... [world-nuclear.org] ) and at some point the volumetric concentration would be sufficient to create conditions of critical mass, and certainly where there are local ore concentrations, the resulting radioactive flux would just kill everybody dead, but also propel ejecta.
Their description if overly simplistic.
Death. (Score:2)
Sun made of fire, sun made of ice (Score:2)
I thought we had already (Score:2)
A black hole where Biden et al are charging into it, pulling all and sundry with them.
What is the point of this? (Score:2)
I can dream up any number of absurd hypothetical scenarios, but why? Anyway, this reminds me of a Greg Egan novel. Not that he wrote one about this, just that it's something he might write about.
Ummm, (Score:2)
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trip-sitting...lol first time I've heard that term
but truly.... having a sober, reliable friend on stand-by is the smart way to do these types of things; also be in a safe, comfy place that you can sleep if necessary; and drink *plenty* of water
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The entire thing is about a change in mass, not a single bit about a change in density, proving the fucking writer doesnt actually know jack fucking all about black holes in actuality, because only one of these fucking makes a black hole and it aint the fucking one he said.
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I was expecting the ending of that Disney movie.
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Then it would evaporate very quickly since it would pass through solid matter without interacting, unless it happened to pass directly through an atomic nucleus so that it could absorb at least part of it. Statistically, that wouldn't happen nearly often enough to replace the mass being continuously emitted as Hawking radiation.
Unless we fundamentally misunderstand something about the physics which would cause it to evaporate much more slowly than we believe. In which case it would orbit around inside the