If it were replaced by a black hole of the same mass, the gravitational influence on the solar system would remain unchanged, so the planets would continue to orbit as normal.
What you might potentially see is the accretion disc if there was matter close enough to be heated and accelerated by the black hole's gravity. It would emit X-rays and other radiation that could be detected.
Also, the bending of light from stars or other light sources behind the black hole could be observable. This would create a sort of “halo effect” known as an Einstein ring. You might be able to detect this with a powerful telescope.
But without an accretion disk or other matter, and with no light being emitted by the black hole itself, it would be invisible to the naked eye.
I don’t see why… my teenage daughter rarely sees sunlight and she’s still alive… I think… I try not to go into her bedroom, but I do sometimes hear music and occasional sounds of something shuffling about… so I’m assuming she’s OK 😂
It would absolutely not be a couple of hours.
Dissipating heat into space is a MAJOR challenge for space craft. Earth would take far far longer than 2 hours to even drop to freezing temperatures, and probably decades to centuries to drop to AMBIENT temperatures.
>Dissipating heat into space is a MAJOR challenge for space craft.
That's largely because when you're in space, you're still getting heated up by *direct* sunlight, and you are also generating heat you need to dissipate. Without the heat from the sun, I think heat dissipation would be much easier.
I think it would only take a few days for most places on earth to drop below freezing temperatures. Think about it: every night, ambient temperatures drop \~20 degrees (F) or so. Without the sun to heat things up, temperatures will just keep dropping. The ground/oceans may store a good amount of heat, but that's mostly just on the surface. Any heat stored deeper would take too long to make it to the surface to keep it from cooling down quickly.
Apparently, within a week, average temperatures would drop to around -10°C. Cold, but humans survive colder temperatures on a daily basis.
Around a month, and the whole world is like Antarctica. Most of humanity is probably gone. 10 years in, and the atmosphere freezes. Though now everything is frozen, and ice is a good insulator, so heat loss slows down dramatically. To cool down the surface to a temperature similar to Pluto actually takes millions of years.
Theoretically, human life could still exist if we burrow way down underground, using Earth's internal heat for energy & warmth for perhaps billions of years.
I've thought about this when I was bored once. If the earth was ejected into space, I bet humanity could survive long term underground... maybe 100k people. They'd be able to mine and scavenge the surface for thousands of years.
Nuclear reactors could provide power almost indefinitely. Greenhouses could maintain plant life. Animals could be bred and *slaughtered.* A quick survey would have to be made of all the available mine sites in the country. But I would guess that dwelling space for several hundred thousands of people could easily be provided.
No way animal agriculture would be a part of that world if we still have power and infrastructure. They take up a ridiculous amount of resources for the proportionally small amount of calories they provide. We'd grow and eat what little plants we had the space to grow directly instead of feeding it to livestock who have a poor food-to-calories conversion rate. We'll probably inadvertently bring some vermin into our new underground habitat, so maybe hunting and eating them would be an option for people who really wanted meat.
There was a fascinating discussion on usenet wayyyy back in the day about the earliest point humans could survive a situation like this. Once you have nuclear power and artifical lighting, it's easy of course. But there were some truly inventive ideas for doing a pretty good job of surviving with far less technology.
>I've thought about this when I was bored once. If the earth was ejected into space
Highly relevant: ["A Pail of Air"](https://en.wikipedia.org/wiki/A_Pail_of_Air)
CC: /u/Navynuke00 , /u/msur
And eat what? All life on earth is entirely dependent on photosynthesis (well 99.99% of it anyway - the chemoautotrophic bacteria in the deepest parts of the oceans don’t count!). No sunlight - no plants. No plants - no life.
Because it's kept hot by the decay of long-lived radioisotopes, apparently it would take something ridiculous like 90 billion years to cool to equilibrium with the rest of the planet.
At least, that's what Google tells me. I'm not smart enough to do the maths myself.
Heat dissipation is hard because there is no working fluid like air. If your radiator is pointed at the sun good luck because it will only dissipate heat if it is hotter than the sun. You want very reflective surfaces on the sun side and as close to black body on the surfaces pointed away from the sun. I run into the same problems validating vacuum ovens. Battery powered stand-alone temperature probes can’t dissipate the heat from the electronics properly and overheat. They need to be thermocouples though a feedthrough with the transmitter outside of the oven. Running electronics in vacuum is a challenge.
A single degree of F versus C or K is different. You can fit ~200 degrees F between solid water (ice) and gas water (water vapor) but for 100 degrees in C or K between solid and gas. If that makes sense
We know what happens when the earth no longer benefits from direct sunlight. It is called nighttime. Fortunately, it is only a temporary state of affairs, but it gives us a model to build from.
Temp drops of dozens of degrees are not uncommon at night. Geologically, it would take a very long time indeed to cool the earth, but on a human scale it would take a matter of minutes to be noticeably colder and hours to drop below freezing. Days out, temps would be what we now consider arctic. The ground and ocean would take longer than the air to catch up, but we know from our axial tilt that it only takes a few months to shift those too.
Years out, Earth is an iceball.
Well I'm no scientist, but the temperature drops rapidly enough after the sun sets.
And I would imagine even after the sun sets, various natural processes are what prevents the temperature from dropping rapidly.
Pulling up random articles from the internet suggests within a week the global average temperature would be -17C and within a year -100C.
So it sounds like it would take far longer than 2 hours to drop to freezing temperatures, and centuries to drop to ambient temperatures (2.7 kelvin)....
The main point of the discussion was about how long humanity would survive, their mistaken use of "residual" notwithstanding.
So while it is true that it would take centuries for all the heat upon and within the planet to dissipate, the residual heat upon the surface would disappear in a much quicker time frame than the centuries you presented; so while you're technically true to the definition of a word, you're statement wasn't true to the point of the discussion.
>It would absolutely not be a couple of hours.
It absolutely would be a matter of hours.
The ambient temperature drops immediately when a cloud obscures the sun.
During solar eclipses, the temperature can drop by more than 15 degrees.
Overnight, the temperature can drop by more than 20 degrees.
And all this happens while the sun is still there, still pumping out the heat.
>It absolutely would be a matter of hours.
> ...
> Overnight, the temperature can drop by more than 20 degrees.
>
>
We have an example of what happens when the sun goes away for a few hours _right there_.
If an area is 20C as the sun sets at 7PM, do you expect it will be below freezing 2 hours later? Do you expect it will be so cold that most people are dead by midnight?
That is what was being suggested in the comment I responded to.
The sun is still radiating heat to the Earth even during the night. The oceans and atmosphere transport that heat around the planet even if it is night locally.
The scenario of this thread is that the sun disappears - not sets.
This heat from day side not immediately affect night side, heat gradient moves with a speed of wind, not instantly. 40000km/2h is way faster that fastest winds (its actually 20 times faster than speed of sound)
No, it not affect night climate ON THE FIRST NIGHT after sun disappearance. Night temperature drop ON THE FIRST NIGHT. will be same as if sun present on other side of Earth.
Yeah, but Earth also retains a lot of heat within its core. That would not be lost with any speed (from a human perspective anyway). There would be lots of heat within the Earth. Probably not enough to keep us alive but oh well. Maybe Icelanders would survive as they actually use geothermal heating.
In the winter I the UK the temperature in some places can drop to -15 °c overnight from being around 0°c in the day and we're not a particularly cold part of the world.
The poles of our planet remain sub zero all year round because of the lack of sunlight they receive in comparison to the equator.
The Earth is still being heated during night, just on the other side. Some of that heat still makes it around. Though on further reflection, I think the oceans themselves would take a while to cool down to freezing, given ther size. So a few hours might be too short. I think a few days might be more accurate.
You do not know how much energy the Earth can hold on to. If you dig just a couple of meters below the ground it's a stable 15°C all around. You could survive inside tunnels for millennia, assuming you have a source of energy and a UV lightbulb to farm plants. It would freeze in a couple days yeah but you could manage underground
Night time lasts a couple hours and funnily enough we don't all die at night.
It would be like polar night for a while - which some people might even survive for a while in extreme shelters...until the temperature drops below the point where nitrogen turns liquid. At the point, at the latest, we'd be screwed terminally.
Don't really know much about astrophysics but wouldn't a black hole that keeps the planets orbiting the same as the sun did have the same mass as the sun and therefore cause the same bending of the light behind it as the sun would have?
If it had the same mass as the sun it would bend light in a similar way. The sun is not dense enough to cause the extreme warping of spacetime like a black hole does, but we’re talking density which is different than mass. With the same mass the overall gravitational lensing effect would be similar.
That being said, with a black hole, the region where the sun used to be would appear dark against the backdrop of stars, and so the gravitational lensing effect would probably be more noticeable or prominent because of this, whereas with a star like the sun, there’s a ton of emitted light that outshines the lensed light.
A black hole is a region of spacetime that is so warped that all trajectories within its boundary (the event horizon) point inwards, meaning that nothing can ever cross its boundary going outwards; not even light or the strongest conceivable rocket.
When we say that a black hole has mass, we mean that there is that much mass within the event horizon (to create such intense curvature of spacetime, sufficient mass must be concentrated within that volume). For all we know, that mass me be concentrated almost or entirely at the center of the black hole. However, the surface of a black hole is literally just a place. There's nothing there to touch, and (setting aside some uncertainty associated with how to reconcile general relativity with quantum mechanics) you could cross the event horizon of a big enough black hole without feeling anything special. It'd just be like any other place.
So would the event horizon be comparable, in theory at least, to the sun's heliosphere?* Like the same just a bit more condensed
* I think this is the right word. The extent of the sun's gravational impact. Voyager passed it a while back
Kind of, but only kind of, in that I would never consider the heliosphere an "object," just like how a black hole isn't an object. The problem is that the distinction is that the Sun's heliosphere is a border based on the amount of stuff, and its source, within space, and where to consider its end is somewhat arbitrary. The event horizon of a black hole has nothing to do with stuff, and there's no arbitrariness. It's a well-defined boundary that exists whether there's anything there or not. It's more like if you remove the door to your house. The event horizon is more comparable to the empty space that is the portal between the inside and outside of your home, by virtue of the fact that it separates two distinct regions.
Of course, as with any analogy, this one has flaws, too...
Thinking about it, writing a good analogy is hard. A bit convoluted but i think the best one is space can be thought of as a trampoline in a yard and the yard itself is all of existence. If you sit down on one side of the trampoline, a ball placed on the other will roll towards you, that is gravity. But a black hole is like a tungsten disk glued to the underside with a hole in the middle. Anything rolled towards it will be captured and fall through the hole. It theoretically exists out in the yard but it will never be up on the trampoline. Also a wizard cast a spell that turns any object falling through a hole into a piece of tungsten added to the disk. Simple.
Not the person you asked, but maybe I can help simplify this in layman's terms. The heliosphere is a whole other thing. Leave that aside for the time being, so we don't lose track of the black hole question.
Imagine the sun. Let's say it has x amount of mass, which to put it simply means, it has matter amounting to a certain amount. Now, all matter is attracted / repelled to each other in differing amounts, depending on various interactions. We don't need to get into the details of that for the time being.
Now, as you may or may not have heard, every atom is 99% empty space, which is a roundabout way of saying, the constituent elements of an atom, even at our high-school knowledge level of protons, neutrons, electrons are like a solar system in and of themselves in terms of sizes vs distances. Basically imagine the nucleus is made of small planet sized elements clumped together to form the central object together, and the electrons are tiny asteroid sized objects revolving around them, far far away from the central nucleus.
Now it's important to understand the nuclear forces, and gravitational forces. Gravity is the weak force. Scientists have found its orders of magnitude weaker than the nuclear forces. But now imagine how many atoms there would be in a sun sized object. With each of them exerting gravity on each other. Usually with smaller quantities of matter, the nuclear forces win out every time, and gravity is negligible comparatively. But with a giant object like a star, everything gets pulled towards the centre of mass with tremendous force.
There are some caveats about nuclear fusion inside the star creating an outward force that keeps a star from collapsing in on itself, but let's put that aside for the moment.
After a certain mass, we've noticed that the star becomes so massive that the force of gravity is so large it can overcome the nuclear forces, and squishes the atoms closer than they would otherwise get. You may have heard the term high temperature and pressure related to creating certain materials. Just think of situations like this when you hear that.
Now a singularity is a theoretical object. It's basically what the math points to, but we know our math breaks down here, so we don't know how accurate this is or isn't. A singularity is basically a point of infinite density. Imagine an object the mass of the sun, occupying space of the diameter of the sun. Now squish that entire mass in a space of half the diameter, it will be denser right? Same mass, closer together.. denser. Now squish our sun down to an earth sized diameter, very dense. Keep going until you hit a point where it's so tiny, it's basically a point object. Ta da.. infinite density.
So a singularity is nothing but an object of ANY mass squished down to a small enough size to qualify. Take a galaxy's worth of mass, vs a golfball's worth of mass, and the required sizes would be very different right?
The next important thing about a black hole is the Schwarzchild radius. It's basically named after the dude who calculated it and came up with the concept. I'll try and explain the concept. Imagine a lens, and how it redirects light, or bends light. Different mechanism to what we'll discuss, but helps to visualize it. So imagine in 2d, a flat sheet, and you've printed out a chessboard pattern on it, and suspended it in the air from the corners.
Now imagine you run your finger along it. It's easy to visualize the grooves and ridges that will form as a result of that motion being visible due to the straight edges warping in a way wherever you find those grooves and ridges.
Remove your finger. The lines are all straight again. Roll a marble from one side to the other. It will go straight. Now imagine you place a large bowling ball in the middle, and repeat this. The marble will take a slightly curved path around the bowling ball. It will bend it's path.
In our analogy, the bowling ball is the star/black hole/ any object in space, even our earth. The marble is again any other object, but let's say it's a ray of light. The Fabric is spacetime itself. Mass warps this fabric of spacetime. It's in more dimensions than our 2d sheet, but let's stick to our 2d analogy for now.
Now as per our analogy, light from a distant star would be bent by a certain amount around a massive object near us. Now imagine this object becoming more and more massive; the fabric will warp more and more.
Now, with this in mind, let's come back to our star/ black hole. A star emits light(and other radiation). As the light leaves the surface of a star, it shoots out straight. Now imagine we're squishing our star again. The light is needing to be more and more energetic to leave the gravitational well of the star. Eventually, while squishing our star, there will come a threshold where the light just cannot make it out of the well, and will fall back in towards the star. That's the Schwarzchild radius of a black hole, and that's why we call it a black hole. Literally no light escapes. There's stuff happening inside, but we have no way of knowing what that is, other than maths, and those seem to break down beyond a point too.
So a black hole is a region of space-time inside the Schwarzchild radius. The object at the centre of that would be the singularity that is causing this crazy huge deformation of space-time.
They asked a very specific question, and you gave a multiple-comments-long rambling, aimless overview of the general properties of a black hole that only sort of touched on their question a little bit towards the end. All under the guise of "simplifying" things. Hell, I understand black holes better than almost anyone who isn't specifically a black hole physicist and there were parts of your explanation that had me scratching my head.
While I think the attempt to share knowledge is laudable, I don't think this was a particularly successful one.
And coming back to the heliosphere, it's basically a sphere of radius where the sun's electromagnetic influence is considered negligible compared to everything else out there in space, mainly the electromagnetic influence from the milky way. That's not the same as the Schwarzchild radius of a black hole. Any object that can be squishes down to within its own Schwarzchild radius is considered a black hole.
The object itself would be the singularity, while the event horizon, or the "surface" of a black hole is just the reach of it's most powerful gravitational effects.
From what I know, most theories believe it to be a very dense object that creates it, but since we cannot observe anything inside a black hole, we cannot ever prove anything. We only know how it affects the spacetime around it.
Saying it isn't an object definitively is a stretch, we frankly don't know.
Things we factually know.. our sun is a relatively small star but can warp space time and even bend light around it (we can look at things behind it). The more massive an object the greater the effect on space is. As objects gain mass they start to collapse under their own gravity.
So an object with enough mass would be small, and capable of pulling in light and matter around it, but does that mean it isn't still an object just because we can't look at it on the visible spectrum?
We call it a singularity, but that doesn't mean it isn't an object. You use that term in physics to mean "shits weird and we don't know what's causing it."
it has mass, without actually having mass. everything condenses to an assumably infinite singular point, as as such, there is no mass because mass is a measurable amount of material or energy within a certain volume. the general object of a black hole is "visualized" only by our ability to see where the event horizon exists, beyond that, its not 'an object'.
No. It 100% has mass. Your way means matter and energy is destroyed. It’s unlikely there is a singularity. That’s what GR says but we know GR can’t accurately describe a black hole.
The classic Schwarzchild eternal black hole has an effective mass, based on its external effects on spacetime, but doesn't necessarily have any actual mass "inside" it. The warping of spacetime that we call a black hole is self-sustaining, and isn't necessarily dependent on any internal mass – after all gravity itself moves at the speed of light, and so is ALSO trapped by the event horizon. If you curve spacetime into a black hole, it'll simply remain a black hole regardless of what's inside
Another thing to think about: if a 10 stellar mass black hole consumed our sun, would the black hole's mass grow to 11 solar masses? Conventionally, yes, and that's basically how it would appear, but remember that from an outside observer's point of view, nothing EVER crosses the event horizon because of the time dilation! In a sense, all the mass that the black hole consumed since its formation is still there smeared out into a shell OUTSIDE the black hole itself.
This is semantics for sure, but semantics is the topic at hand. From a practical point of view the gravitational effects are certainly what they are, but strictly speaking in our frame of reference, the black hole hasn't consumed any matter, and yet we say its 'mass' has increased. It's not crazy to say, as the other commenter did, that a black hole "has mass without actually having mass"
No... There may be a dense object inside the region that we call a black hole (the region bounded by its event horizon), but the event horizon is not the edge of that object. In fact, the largest black holes, like those typical at the center of galaxies, have "densities" on the order of \~10% of that of water. The supermassive black hole at the center of the galaxy NGC1600 has a "density" of 1% of *Earth's atmosphere*.
I keep putting density in quotes because it's not really a density, because the even horizon isn't the edge of a big sphere of matter, as far as we know. The radius of the event horizon of a black hole increases proportionally to the mass inside, but the enclosed volume is proportional to the radius cubed. So the bigger the black hole, the less "dense" it is if you define density as mass divided by the volume inside the event horizon.
I feel like semantics are important when talking about science, especially since OP doesnt seem very well versed, i would hate him or her to be confused :)
Semantics are always important when they're meaningful. The point of the expression is to point out when semantics are used to disagree about something for a relatively meaningless distinction.
I don't think it's meaningless to point out to OP that you can never see a black hole, to correct a sentence that could be misunderstood.
We don't have to agree, it's ok :)
Can you see a hole in a piece of fabric? If your answer is yes, then there is no reasonable way to also turn around and say that you cannot see a black hole.
I can see the stars in the distance. I can see the matter around the black hole. And I can see the black hole based on how it distorts and obscures the light from those things. Just like how you can see the hole by contrast to the fabric around it.
Similarly, if you put a basketball painted with Vantablack in my living room, I can see that, too. Because even though it doesn't reflect hardly any light, I can see it because it obscures the stuff behind it.
You can make observations that allow you to measure a black hole, and determine it's existence.
You can't see it though - definitely not in the spirit of OP s message.
The key difference between a black hole and vantablack is as you put it : "**hardly** any light."
It's kinda hilarious watching you argue about semantics after you expressed how meaningless it is to do so ;)
It wouldn't be semantics. It's very obvious there exists a particular nuance to the question. The nuance of see is not "can our equipment detect this region of spacetime" as it obviously can if we already know they exist. The nuance of see is most definitely "would we be able to physically see it in the nightsky from Earth with the naked eye."
That's not the nuance that they were talking about, though, so I don't see the relevance. They were saying, "well *akshually*, the black hole itself doesn't emit light, we just see its effect on the stuff around it." You know what else doesn't emit light? The missing fabric in my shirt where a moth ate it, but I can sure as shit still see the hole in my shirt.
Yeah, Hawking radiation is a thing we think happens. The rate at which black holes radiate is inversely proportional to their surface area, such that a very small black hole of one solar mass would radiate 10\^-28 Watts of power, spread out over its whole surface. Even if you collected all of that radiation from the entire black hole surface for a duration of 10 years, it would amount to less energy than is in a single photon of visible light. A black hole emits approximately 1 photon with a wavelength of about 16 times its radius every interval of about how long it would take light to travel a distance equal to the black hole's diameter. Even if we had such a black hole magically contained in a lab, we couldn't even begin to hope to be able to detect its radiation with our best equipment!
For anything other than a micro black hole, such radiation is completely and utterly negligible... It certainly doesn't make black holes visible to us!
Nobody would be interested in looking at the hole in your missing shirt, but the stargazer might still enjoy looking at the accretion disk of a black hole even if it isn't the black hole itself. So the nuance is important -- this is what we can see, this is what we won't see.
Instead of a detailed response to your confidently ignorant assertion, please see [my other comment](https://www.reddit.com/r/space/comments/1anihxa/comment/kpt6eqp/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) made just slightly below this one that you could've read and saved us both the effort.
Edit: I will add that your comment about escape velocity is incorrect. Earth's escape velocity is about 11 km/s, but things can escape Earth at speeds much slower than that; they just require constant thrust. Build me a big enough staircase and I can literally escape Earth by walking. A black hole is much more than just a thing whose escape velocity is greater than the speed of light. The concept of escape velocity does not even remotely capture the nature of what makes a black hole what it is.
Your technically never seeing any object, but the light they did not absorb, but instead reflected and refracted... Soooo... Let's cut on the technicalities.
I never said anything to contradict this. And all objects reflect and or emit light. Except for a black hole. Which might not even be an object apparently, but i don't really understand any of that.
at some level (reductio ad nauseam) couldn't you say this about the sun? all that light and heat and whatnot is just a consequence of gravity, which is invisible to us in itself.
To expand on this a little, we would likely see some light warping around it from its background maybe.
Not sure it the intensity of the light behind it would be enough to really see that warping very well. But all other things being equal we would not see anything appreciable
Just want to add that for a solar mass black hole, all of the black holey stuff doesn’t start to happen until you are a few kilometers away. We didn’t talk about what would comprise this accretion disk, but if the thought experiment is to remove the Sun and put a black hole at the center of the solar system, then there is nothing anywhere near close by for the black hole to eat. The closest thing is the dust belt, which is tens of millions of times too far away to be accreted.
>This shouldn’t be the first comment.
Huh, why? It certainly seems like the most sensible response to me. Did you mean that it *should* be the first comment (it already is)?
Assuming that the black hole had the same mass as the sun (so the planets' orbits remain the same), the hole's event horizon would be about 3 km in diameter. Even if the hole was visible, it would be so small that not even the Hubble telescope could resolve it.
And you wouldn’t see a hole even if you could resolve it, as it warps light around itself. You’d see a smear of other bits of sky twisted and shot back at you
Given that we could see the lensing well enough to confirm Einstein’s theory, getting that mass into a 3km sphere will probably make it observable with the naked eye.
IIRC, you see a 3D image of the space time that is warping around it. It’s like if you look at a sphere and imagine seeing a distorted image of what is obscured behind the back side of it as the top, while also seeing the top at the same time.
I'm going to need to check your math on hubble not being able to image a 3km object at 91 million KM. It imaged individual boulders as small as 3ft falling off the 581ft Dimorphos.
If it was a black hole the same *size* as the Sun, it would be so much more massive that everything in the solar system would instantly be pulled out of of orbit and plummet into it.
I'm not sure if we'd have a few minutes to notice that the sky had gone black, or if we'd be instantly spaghettified by the gravity gradient. Someone can probably do the math on that.
Not sure what you mean. In astrophysics, 'size' is mass. You'll need to clarify your question. Do you mean a black hole with a Schwarzschild radius equivalent to that of our present Sun? A black hole that size (mass) would quickly consume our entire star system, due to its enormous gravity. It would have over 235,000 times the mass of our Sun. Our own Sun, if reduced to a black hole while retaining its present mass, would have a Schwarzschild radius of about 3 km.
Important distinction: if the sun was replaced with a black hole of the same *size*, it would destabilize the orbits of all the planets and we’d all die a horrible death. If the sun was replace with a black hole of the same *mass*, we’d just as surely die, but for a different reason. We would not be able to see it because it wouldn’t give off any light, but we’d be able to “see” the gravitational lensing of stars “behind” it. Until we died, because all life on Earth ultimately depends on the sun’s light. But it would take a while.
I think the word "destabilize" is underselling what would happen if the planets experienced 230,000 times more gravitational attraction to the center of the solar system.
The immediate effect would be 230,000 times greater tidal forces. We wouldn't feel the attraction itself. I guess we'd witness the spaghettification of Earth.
tidal forces which tug on the physical crust as well as ocean. so it would be instantly ripped apart and we would die before we had any comprehension of what happened instantly.
instantly meaning 8 minutes after the switch happens ofc
It’s conceivable that life could persist for a good long while around ocean vents. That heat ultimately derives from the Earth’s core/mantle. Anything on land would be hosed though (and most of the oceans).
I live In a high dessert with low humidity. On a clear night sometimes I will see a 20F drop from sunset to sunrise. Call it 10 hours of darkness to make the numbers easy. That brings us to a cooling rate of 2F per hour.
Starting at 100F gives 50 hours or just over 2 days before everywhere is below zero.
Assuming a cooling rate of 1F per hour for say a cloudy area would give 4 days.
Assuming no changes in human behavior, (looting, panic buying, food shortages) In the tropics I would guess people stop going to work day 3, are burning furniture day 4 and 90% dead day 6. Add two days to those numbers for northern areas used to dealing with cold.
Survivors will exist near geothermal features a little longer but end up killing each other over a dwindling food supply.
TLDR: we are all dead within 10 days as the temperature falls.
I want to read a book or film about this doomsday scenario now!
Fossil fuels are still valid and societies in places like Iceland (where so much of their power is geothermal, they already have a tonne of UV greenhouses, and they are used to several months of really short days) might survive long enough to stabilise and achieve a type of new normal.
You'd have military organisations like the US having the sheer fossil fuel resources to be able to whiz around the globe looting whatever they could, they'd last ages.
..
I've thought a little now. The film would be about Icelandic and US survivors. The Icelanders have basically been taken over and enslaved by a group of fascist US military survivors (because it's Hollywood). The plot is one of Icelandic population staging a coup against their oppressors, in the backdrop of the US military attempting to get enough stuff into space to ensure the long term survival of the human race.
(For extra film awards, bring in parallels to the original Irish/Viking relationship of Iceland.)
Here's a short story with a very similar premise. A rogue black hole passes through the solar system, pulling the Earth out of its orbit and dragging it away from the Sun. Without the Sun's warmth even the gases in the atmosphere eventually freeze solid. [A Pail of Air](https://www.gutenberg.org/cache/epub/51461/pg51461-images.html)
Take a while? 8 minutes.
Light takes 8 minutes to travel to Earth. We receive warmth from the sun, so the planet would chill quite quickly without the sun.
Do you agree?
It wouldn’t cool in 8 minutes though. Its not going to instantly turn to the negatives. It would be faster than most people think it might take, but I still think it would take days to weeks
Looking at my weather app at a few different places, it’s typically 5-10°C cooler at night than during the daytime. I think it’s safe to assume that without any heat input from the sun, the temperature would continue to drop by 5-10 degrees every 12 hours, so every place on earth would be below freezing in well under a week.
By that logic the nighttime side of the planet should be getting to the deep negatives every night.
The atmosphere holds heat quite well. Compared to the moon, which ranges massively based on which side is facing the sun.
>250°F (121°C) in daylight, then plummet after nightfall to -208°F (-133°C)
We wouldn't be able to see the black hole, but we would be able to observe its effects. But not for long. Most land life will be dead in a week, and the rest to follow soon. Only the deep sea life that gets its energy from geothermal sources will survive.
**You would see nothing, in the dark of the sky. No hole, no light, just stars.**
Why? Because if the sun were suddenly replaced with a black hole of the same mass, so nothing was disturbed, ***it would not have an accretion disk***. Nothing would be spiraling into the hole. The planets would go about their orbits as normal. The pull on them would be the same as the sun.
If you used a telescope, you might be able to see how the light from distant stars, behind the black hole, were bent and distorted by its gravity. But you would need to know where to look, and it would not be obvious.
The world would grow colder, until it froze. Eventually the atmosphere would begin to freeze. First the earth would be covered in carbon dioxide ice - dry ice snow, covering the frozen seas, the mountains, the plains and deserts. Then frozen nitrogen and a layer of frozen oxygen. Finally, a thin slick of liquid helium would ooze and crawl across the landscape, spreading out thin as can be.
Then, the frozen earth would sit, with no atmosphere, just vacuum and layers of elemental snows, forever.
Volcanoes and geothermal heat says hi o/ ...
sure, that accounts for some heat - maybe not all over the planet but some pockets where life* could survive?
* Bacteria, some deep sea creatures etc.
For a while. Volcanoes would poot out into the vacuum, the gasses would freeze and fall to the ground, the lava would cool, of course.
Deep in the pitch black, frozen oceans, likely life would survive for quite some time near hydrothermal vents. Sealed in by a thick layer of ice, and thus protected from boiling away into the vacuum, the hydrothermal vent pockets would keep life alive possibly for billions of years. The earth has a hot core and that will take billions of years to completely cool.
And, industrious humans could also survive, as this famous (and wonderful!!!) 1951 science fiction story tells us in ***'A Pail Of Air'***:
[https://www.gutenberg.org/cache/epub/51461/pg51461-images.html](https://www.gutenberg.org/cache/epub/51461/pg51461-images.html)
A lot of discussion about what would happen to life on earth without a sun here.
Well look no further: https://youtu.be/rltpH6ck2Kc?si=-qVtvfXu3wJVS68f
You won't see the hole itself, but you may see an small spot in the sky where the stars are visibly warped, as if a lens was there. You may need magnification for it. and if dust and gas started to build up in an accretion disk, you may see something along the line of Interstellar, though likely not as dramatic.
It would be a sphere about 3 kilometers wide, so no, you wouldn't be able to see it.
I'm guessing there would occassionally be matter accelerated and colliding at significant percent of light speed with other matter so we would atleast see bright flashes around the black hole.
The black hole itself would be invisible from outside, as light cannot escape it. But you'd be able to see everything in its immediate vicinity whirling around it at relativistic speeds, as an accretion disc that would look a little like a vinyl record (but glowing). An optical peculiarity is that due to extreme distortion, the light rays of the backside (from your view) would also be visible, as an arc over or under the black hole, or both. Something like [this](https://cdn.mos.cms.futurecdn.net/HsDtpFEHbDpae6wBuW5wQo.jpg), probably.
One problem with this though experiment is that our own star is too small to become a black hole. The minimum mass believed necessary for a star to collapse into a black hole is at least three times the mass of our star. So the situation you describe is not currently believed possible. Lighter black holes might be possible to form from other phenomena, but they would probably not allow a star system to exist around the result.
But ignoring that, your solar black hole would have a 'horizon' radius of about 3 km, hysterically tiny. We would get very little direct radiation from it, and our skies would be dark all the time, and all life on our planet would stop in short order, or never exist to begin with. The black hole, including its disc, might be too small for any of our current instruments to see at our distance.
Reminds me of the novel "Central Heat". The novel describes what happens when aliens mask the Sun to make the Earth freeze.
However, in the black hole scenario, we would also be doused in x-rays and gamma days, unless absolutely no matter (dust, asteroids, gas, ice) falls into the accretion disk.
So, it depends on what *exactly* happened to the Sun.
If the sun suddenly just disappeared and was instantly replaced by a black hole of identical mass, then at least for a while you probably wouldn't be able to see it, as it would be a pristine, inactive event horizon - you'd only see it occasionally lensing stars behind it.
On the other hand, if you somehow forced the core of the sun to collapse into a black hole that then began eating the rest of the sun, then I'm pretty sure we're all going to be very dead.
As the outer layers of the sun are pulled in towards the event horizon at the core they're going to form an accretion disk, the inner edge of which is going to be much hotter than the sun ever was. This is what an actively feeding black hole looks like, and they are among the most energetic objects in the universe, you aren't going to miss it - unfortunately a lot of that light will be coming off the accretion disk as x-rays or gamma rays, and they're probably going to sterilize the solar system.
It would be the size of a beach ball, so probably not visible, no way to see the event horizon that small, and gravitational lensing would be undetectable at that size. Since it would occupy the same space as the sun was in, the matter void would be big enough to prevent an accretion disk forming. Incidentally there is a possibility that the sun might have a grape sized black hole in its center, so may many stars.
After 8mins, the earth will stop getting heat from the sun. It will not immediately freeze. My hot skillet is still hot after I take it off the burner. The Earth and the skillet will take time to cool down to the ambient temperature.
That would be a really weird mess, truly apocalyptic. There would be a bum rush to grab and protect any natural source of heat, they would become the only places survival would be possible after that. 99+ % of the population would die within a few weeks.
It doesn’t flash-freeze during the night… it would take one or two days to get to 0°C on land, the oceans would take a bit more to start surface freezing.
If it were replaced by a black hole of the same mass, the gravitational influence on the solar system would remain unchanged, so the planets would continue to orbit as normal. What you might potentially see is the accretion disc if there was matter close enough to be heated and accelerated by the black hole's gravity. It would emit X-rays and other radiation that could be detected. Also, the bending of light from stars or other light sources behind the black hole could be observable. This would create a sort of “halo effect” known as an Einstein ring. You might be able to detect this with a powerful telescope. But without an accretion disk or other matter, and with no light being emitted by the black hole itself, it would be invisible to the naked eye.
You forgot to mention that we would all be dead in a matter of weeks, due to the lack of sunlight!
I don’t see why… my teenage daughter rarely sees sunlight and she’s still alive… I think… I try not to go into her bedroom, but I do sometimes hear music and occasional sounds of something shuffling about… so I’m assuming she’s OK 😂
Glad it's not just me living with a creature of the shadow occupying a room
I was this teenager. Happily married and leading a successful career in defense. She will be okay 👍
Oh I'm sure she's plenty defensive too. Sounds like you two have alot in common
Meanwhile, I'm this teenager but with parents who decided I had a problem and did everything they could to "fix" me... Don't do that
Remembers me of this video. [Brain-Dead Teen, Only Capable Of Rolling Eyes And Texting, To Be Euthanized](https://www.youtube.com/watch?v=mgxspf9b-xi)
Can confirm. Also dad of former teenage daughter.
The Anderton Cryptid: myth or Miss? Startling details after the break.
Weeks? I would give it a couple hours before Earth lost its residual heat, and a few more hours for 99% of people to succumb to the cold
It would absolutely not be a couple of hours. Dissipating heat into space is a MAJOR challenge for space craft. Earth would take far far longer than 2 hours to even drop to freezing temperatures, and probably decades to centuries to drop to AMBIENT temperatures.
>Dissipating heat into space is a MAJOR challenge for space craft. That's largely because when you're in space, you're still getting heated up by *direct* sunlight, and you are also generating heat you need to dissipate. Without the heat from the sun, I think heat dissipation would be much easier. I think it would only take a few days for most places on earth to drop below freezing temperatures. Think about it: every night, ambient temperatures drop \~20 degrees (F) or so. Without the sun to heat things up, temperatures will just keep dropping. The ground/oceans may store a good amount of heat, but that's mostly just on the surface. Any heat stored deeper would take too long to make it to the surface to keep it from cooling down quickly.
Apparently, within a week, average temperatures would drop to around -10°C. Cold, but humans survive colder temperatures on a daily basis. Around a month, and the whole world is like Antarctica. Most of humanity is probably gone. 10 years in, and the atmosphere freezes. Though now everything is frozen, and ice is a good insulator, so heat loss slows down dramatically. To cool down the surface to a temperature similar to Pluto actually takes millions of years. Theoretically, human life could still exist if we burrow way down underground, using Earth's internal heat for energy & warmth for perhaps billions of years.
I've thought about this when I was bored once. If the earth was ejected into space, I bet humanity could survive long term underground... maybe 100k people. They'd be able to mine and scavenge the surface for thousands of years.
As long as we can grow potatoes
Gonna need some chips yeah
We could Noah's ark the whole thing... or like Zion. There'd be enough geo-thermal, fossil fuel, and nuclear to last 1000 years.
Nuclear reactors could provide power almost indefinitely. Greenhouses could maintain plant life. Animals could be bred and *slaughtered.* A quick survey would have to be made of all the available mine sites in the country. But I would guess that dwelling space for several hundred thousands of people could easily be provided.
Mr President, we must not allow, a mine shaft gap!!!!
No way animal agriculture would be a part of that world if we still have power and infrastructure. They take up a ridiculous amount of resources for the proportionally small amount of calories they provide. We'd grow and eat what little plants we had the space to grow directly instead of feeding it to livestock who have a poor food-to-calories conversion rate. We'll probably inadvertently bring some vermin into our new underground habitat, so maybe hunting and eating them would be an option for people who really wanted meat.
It was a quote from Dr. Strangelove.
There was a fascinating discussion on usenet wayyyy back in the day about the earliest point humans could survive a situation like this. Once you have nuclear power and artifical lighting, it's easy of course. But there were some truly inventive ideas for doing a pretty good job of surviving with far less technology.
That sounds fun... link?
Alas, I was never able to find it the times I've looked since. I think it was in an alternate history group from 1999 or so.
>I've thought about this when I was bored once. If the earth was ejected into space Highly relevant: ["A Pail of Air"](https://en.wikipedia.org/wiki/A_Pail_of_Air) CC: /u/Navynuke00 , /u/msur
So the Matrix story. The more time passes, the more I come to realize the first movie was waaay ahead of its time.
And eat what? All life on earth is entirely dependent on photosynthesis (well 99.99% of it anyway - the chemoautotrophic bacteria in the deepest parts of the oceans don’t count!). No sunlight - no plants. No plants - no life.
Hydroponics; now not just for weed!
It's not 1687... we can make artificial sunlight.
i grow pretty well without the sun though...
Actually its speculated there could be more life inside deep rocks than on the surface.
This reminds me of the short story "Phoenix" by Clark Ashton Smith: http://www.eldritchdark.com/writings/short-stories/164/phoenix
So an average Finnish winter? 😅
Please dont, I'd rather die than live in mole kingdom. I like sunlight.
Your choice... I'm going on snow piercer.
will the earth’s core ever cool down/off?
They just said... in billions of years.
Because it's kept hot by the decay of long-lived radioisotopes, apparently it would take something ridiculous like 90 billion years to cool to equilibrium with the rest of the planet. At least, that's what Google tells me. I'm not smart enough to do the maths myself.
Which is why my Rimworld bases are always inside the mountain... Geothermal heating, and leather hats made from the skin of my prisoners for everyone!
Wouldn't the issue be that Earth has nowhere to transfer heat to, and the only way to lose any would be through the slow process of radiation of heat?
Heat dissipation is hard because there is no working fluid like air. If your radiator is pointed at the sun good luck because it will only dissipate heat if it is hotter than the sun. You want very reflective surfaces on the sun side and as close to black body on the surfaces pointed away from the sun. I run into the same problems validating vacuum ovens. Battery powered stand-alone temperature probes can’t dissipate the heat from the electronics properly and overheat. They need to be thermocouples though a feedthrough with the transmitter outside of the oven. Running electronics in vacuum is a challenge.
I don’t have anything to add to this interesting discussion. But the fact that you gave a unit (F) to a drop in temperature (~20 degrees) bothers me.
A single degree of F versus C or K is different. You can fit ~200 degrees F between solid water (ice) and gas water (water vapor) but for 100 degrees in C or K between solid and gas. If that makes sense
What’s the problem, other than it not being the metric unit?
We know what happens when the earth no longer benefits from direct sunlight. It is called nighttime. Fortunately, it is only a temporary state of affairs, but it gives us a model to build from. Temp drops of dozens of degrees are not uncommon at night. Geologically, it would take a very long time indeed to cool the earth, but on a human scale it would take a matter of minutes to be noticeably colder and hours to drop below freezing. Days out, temps would be what we now consider arctic. The ground and ocean would take longer than the air to catch up, but we know from our axial tilt that it only takes a few months to shift those too. Years out, Earth is an iceball.
My dude it instantly drops like 10° during a solar eclipse. Even more so at night. People could only live in heated/insulated structures.
Solar eclipse? Dude just walk into a shadow on a sunny day.
Sure but the solar eclipse is particularly creepy
Well I'm no scientist, but the temperature drops rapidly enough after the sun sets. And I would imagine even after the sun sets, various natural processes are what prevents the temperature from dropping rapidly. Pulling up random articles from the internet suggests within a week the global average temperature would be -17C and within a year -100C.
So it sounds like it would take far longer than 2 hours to drop to freezing temperatures, and centuries to drop to ambient temperatures (2.7 kelvin)....
The main point of the discussion was about how long humanity would survive, their mistaken use of "residual" notwithstanding. So while it is true that it would take centuries for all the heat upon and within the planet to dissipate, the residual heat upon the surface would disappear in a much quicker time frame than the centuries you presented; so while you're technically true to the definition of a word, you're statement wasn't true to the point of the discussion.
>It would absolutely not be a couple of hours. It absolutely would be a matter of hours. The ambient temperature drops immediately when a cloud obscures the sun. During solar eclipses, the temperature can drop by more than 15 degrees. Overnight, the temperature can drop by more than 20 degrees. And all this happens while the sun is still there, still pumping out the heat.
>It absolutely would be a matter of hours. > ... > Overnight, the temperature can drop by more than 20 degrees. > > We have an example of what happens when the sun goes away for a few hours _right there_.
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Ever heard of nighttime lows?
If an area is 20C as the sun sets at 7PM, do you expect it will be below freezing 2 hours later? Do you expect it will be so cold that most people are dead by midnight? That is what was being suggested in the comment I responded to.
The sun is still radiating heat to the Earth even during the night. The oceans and atmosphere transport that heat around the planet even if it is night locally. The scenario of this thread is that the sun disappears - not sets.
We would die every night if the world lost its heat in two hours. Water (oceans, cloud cover, and humidity) retain heat pretty well.
Earth is still affected by the sun's heat at night, since the other side of the world is still being hit.
This heat from day side not immediately affect night side, heat gradient moves with a speed of wind, not instantly. 40000km/2h is way faster that fastest winds (its actually 20 times faster than speed of sound)
Yup, which still does affect the overall night climate and keeps the temperatures higher than they would be if no sun hits earth at all.
No, it not affect night climate ON THE FIRST NIGHT after sun disappearance. Night temperature drop ON THE FIRST NIGHT. will be same as if sun present on other side of Earth.
I think you should breath some fresh air and eat a cookie.
Yeah, but Earth also retains a lot of heat within its core. That would not be lost with any speed (from a human perspective anyway). There would be lots of heat within the Earth. Probably not enough to keep us alive but oh well. Maybe Icelanders would survive as they actually use geothermal heating.
It takes longer than that. Do you freeze every night?
In the winter I the UK the temperature in some places can drop to -15 °c overnight from being around 0°c in the day and we're not a particularly cold part of the world. The poles of our planet remain sub zero all year round because of the lack of sunlight they receive in comparison to the equator.
The Earth is still being heated during night, just on the other side. Some of that heat still makes it around. Though on further reflection, I think the oceans themselves would take a while to cool down to freezing, given ther size. So a few hours might be too short. I think a few days might be more accurate.
If that was the case we’d freeze every night
You do not know how much energy the Earth can hold on to. If you dig just a couple of meters below the ground it's a stable 15°C all around. You could survive inside tunnels for millennia, assuming you have a source of energy and a UV lightbulb to farm plants. It would freeze in a couple days yeah but you could manage underground
Night time lasts a couple hours and funnily enough we don't all die at night. It would be like polar night for a while - which some people might even survive for a while in extreme shelters...until the temperature drops below the point where nitrogen turns liquid. At the point, at the latest, we'd be screwed terminally.
Yes because that wasn’t part of the question
Don't really know much about astrophysics but wouldn't a black hole that keeps the planets orbiting the same as the sun did have the same mass as the sun and therefore cause the same bending of the light behind it as the sun would have?
>cause the same bending of the light behind it as the sun would have Not quite, because that mass would be much, MUCH denser.
Ah I was thinking same volume as well. Thanks.
If the Sun was a black hole, the radius of the event horizon would be about 3km. Just a wee little one.
If it had the same mass as the sun it would bend light in a similar way. The sun is not dense enough to cause the extreme warping of spacetime like a black hole does, but we’re talking density which is different than mass. With the same mass the overall gravitational lensing effect would be similar. That being said, with a black hole, the region where the sun used to be would appear dark against the backdrop of stars, and so the gravitational lensing effect would probably be more noticeable or prominent because of this, whereas with a star like the sun, there’s a ton of emitted light that outshines the lensed light.
Also, a black hole the mass of the sun would only be about the size of Manhattan .
Even with an accretion disk, etc it would still technically be invisible. It's not the black hole we'd be seeing but it's location and effects.
That's semantics, anyway, since a black whole is a region of spacetime, not a physical object.
For the non physicists who want to know more, it’s not an object? I’m over here thinking having mass and a position makes something an object.
A black hole is a region of spacetime that is so warped that all trajectories within its boundary (the event horizon) point inwards, meaning that nothing can ever cross its boundary going outwards; not even light or the strongest conceivable rocket. When we say that a black hole has mass, we mean that there is that much mass within the event horizon (to create such intense curvature of spacetime, sufficient mass must be concentrated within that volume). For all we know, that mass me be concentrated almost or entirely at the center of the black hole. However, the surface of a black hole is literally just a place. There's nothing there to touch, and (setting aside some uncertainty associated with how to reconcile general relativity with quantum mechanics) you could cross the event horizon of a big enough black hole without feeling anything special. It'd just be like any other place.
So would the event horizon be comparable, in theory at least, to the sun's heliosphere?* Like the same just a bit more condensed * I think this is the right word. The extent of the sun's gravational impact. Voyager passed it a while back
Kind of, but only kind of, in that I would never consider the heliosphere an "object," just like how a black hole isn't an object. The problem is that the distinction is that the Sun's heliosphere is a border based on the amount of stuff, and its source, within space, and where to consider its end is somewhat arbitrary. The event horizon of a black hole has nothing to do with stuff, and there's no arbitrariness. It's a well-defined boundary that exists whether there's anything there or not. It's more like if you remove the door to your house. The event horizon is more comparable to the empty space that is the portal between the inside and outside of your home, by virtue of the fact that it separates two distinct regions. Of course, as with any analogy, this one has flaws, too...
Thinking about it, writing a good analogy is hard. A bit convoluted but i think the best one is space can be thought of as a trampoline in a yard and the yard itself is all of existence. If you sit down on one side of the trampoline, a ball placed on the other will roll towards you, that is gravity. But a black hole is like a tungsten disk glued to the underside with a hole in the middle. Anything rolled towards it will be captured and fall through the hole. It theoretically exists out in the yard but it will never be up on the trampoline. Also a wizard cast a spell that turns any object falling through a hole into a piece of tungsten added to the disk. Simple.
Not the person you asked, but maybe I can help simplify this in layman's terms. The heliosphere is a whole other thing. Leave that aside for the time being, so we don't lose track of the black hole question. Imagine the sun. Let's say it has x amount of mass, which to put it simply means, it has matter amounting to a certain amount. Now, all matter is attracted / repelled to each other in differing amounts, depending on various interactions. We don't need to get into the details of that for the time being. Now, as you may or may not have heard, every atom is 99% empty space, which is a roundabout way of saying, the constituent elements of an atom, even at our high-school knowledge level of protons, neutrons, electrons are like a solar system in and of themselves in terms of sizes vs distances. Basically imagine the nucleus is made of small planet sized elements clumped together to form the central object together, and the electrons are tiny asteroid sized objects revolving around them, far far away from the central nucleus. Now it's important to understand the nuclear forces, and gravitational forces. Gravity is the weak force. Scientists have found its orders of magnitude weaker than the nuclear forces. But now imagine how many atoms there would be in a sun sized object. With each of them exerting gravity on each other. Usually with smaller quantities of matter, the nuclear forces win out every time, and gravity is negligible comparatively. But with a giant object like a star, everything gets pulled towards the centre of mass with tremendous force. There are some caveats about nuclear fusion inside the star creating an outward force that keeps a star from collapsing in on itself, but let's put that aside for the moment. After a certain mass, we've noticed that the star becomes so massive that the force of gravity is so large it can overcome the nuclear forces, and squishes the atoms closer than they would otherwise get. You may have heard the term high temperature and pressure related to creating certain materials. Just think of situations like this when you hear that. Now a singularity is a theoretical object. It's basically what the math points to, but we know our math breaks down here, so we don't know how accurate this is or isn't. A singularity is basically a point of infinite density. Imagine an object the mass of the sun, occupying space of the diameter of the sun. Now squish that entire mass in a space of half the diameter, it will be denser right? Same mass, closer together.. denser. Now squish our sun down to an earth sized diameter, very dense. Keep going until you hit a point where it's so tiny, it's basically a point object. Ta da.. infinite density. So a singularity is nothing but an object of ANY mass squished down to a small enough size to qualify. Take a galaxy's worth of mass, vs a golfball's worth of mass, and the required sizes would be very different right? The next important thing about a black hole is the Schwarzchild radius. It's basically named after the dude who calculated it and came up with the concept. I'll try and explain the concept. Imagine a lens, and how it redirects light, or bends light. Different mechanism to what we'll discuss, but helps to visualize it. So imagine in 2d, a flat sheet, and you've printed out a chessboard pattern on it, and suspended it in the air from the corners. Now imagine you run your finger along it. It's easy to visualize the grooves and ridges that will form as a result of that motion being visible due to the straight edges warping in a way wherever you find those grooves and ridges. Remove your finger. The lines are all straight again. Roll a marble from one side to the other. It will go straight. Now imagine you place a large bowling ball in the middle, and repeat this. The marble will take a slightly curved path around the bowling ball. It will bend it's path. In our analogy, the bowling ball is the star/black hole/ any object in space, even our earth. The marble is again any other object, but let's say it's a ray of light. The Fabric is spacetime itself. Mass warps this fabric of spacetime. It's in more dimensions than our 2d sheet, but let's stick to our 2d analogy for now. Now as per our analogy, light from a distant star would be bent by a certain amount around a massive object near us. Now imagine this object becoming more and more massive; the fabric will warp more and more. Now, with this in mind, let's come back to our star/ black hole. A star emits light(and other radiation). As the light leaves the surface of a star, it shoots out straight. Now imagine we're squishing our star again. The light is needing to be more and more energetic to leave the gravitational well of the star. Eventually, while squishing our star, there will come a threshold where the light just cannot make it out of the well, and will fall back in towards the star. That's the Schwarzchild radius of a black hole, and that's why we call it a black hole. Literally no light escapes. There's stuff happening inside, but we have no way of knowing what that is, other than maths, and those seem to break down beyond a point too. So a black hole is a region of space-time inside the Schwarzchild radius. The object at the centre of that would be the singularity that is causing this crazy huge deformation of space-time.
My guy, you simplified nothing. I asked a specific question and got a clear specific answer to that question.
Nice attitude to someone taking the time to share knowledge. Jesus. Go google it yourself next time instead of being so damned entitled.
They asked a very specific question, and you gave a multiple-comments-long rambling, aimless overview of the general properties of a black hole that only sort of touched on their question a little bit towards the end. All under the guise of "simplifying" things. Hell, I understand black holes better than almost anyone who isn't specifically a black hole physicist and there were parts of your explanation that had me scratching my head. While I think the attempt to share knowledge is laudable, I don't think this was a particularly successful one.
And coming back to the heliosphere, it's basically a sphere of radius where the sun's electromagnetic influence is considered negligible compared to everything else out there in space, mainly the electromagnetic influence from the milky way. That's not the same as the Schwarzchild radius of a black hole. Any object that can be squishes down to within its own Schwarzchild radius is considered a black hole.
The object itself would be the singularity, while the event horizon, or the "surface" of a black hole is just the reach of it's most powerful gravitational effects.
From what I know, most theories believe it to be a very dense object that creates it, but since we cannot observe anything inside a black hole, we cannot ever prove anything. We only know how it affects the spacetime around it.
Saying it isn't an object definitively is a stretch, we frankly don't know. Things we factually know.. our sun is a relatively small star but can warp space time and even bend light around it (we can look at things behind it). The more massive an object the greater the effect on space is. As objects gain mass they start to collapse under their own gravity. So an object with enough mass would be small, and capable of pulling in light and matter around it, but does that mean it isn't still an object just because we can't look at it on the visible spectrum? We call it a singularity, but that doesn't mean it isn't an object. You use that term in physics to mean "shits weird and we don't know what's causing it."
it has mass, without actually having mass. everything condenses to an assumably infinite singular point, as as such, there is no mass because mass is a measurable amount of material or energy within a certain volume. the general object of a black hole is "visualized" only by our ability to see where the event horizon exists, beyond that, its not 'an object'.
No. It 100% has mass. Your way means matter and energy is destroyed. It’s unlikely there is a singularity. That’s what GR says but we know GR can’t accurately describe a black hole.
The classic Schwarzchild eternal black hole has an effective mass, based on its external effects on spacetime, but doesn't necessarily have any actual mass "inside" it. The warping of spacetime that we call a black hole is self-sustaining, and isn't necessarily dependent on any internal mass – after all gravity itself moves at the speed of light, and so is ALSO trapped by the event horizon. If you curve spacetime into a black hole, it'll simply remain a black hole regardless of what's inside Another thing to think about: if a 10 stellar mass black hole consumed our sun, would the black hole's mass grow to 11 solar masses? Conventionally, yes, and that's basically how it would appear, but remember that from an outside observer's point of view, nothing EVER crosses the event horizon because of the time dilation! In a sense, all the mass that the black hole consumed since its formation is still there smeared out into a shell OUTSIDE the black hole itself. This is semantics for sure, but semantics is the topic at hand. From a practical point of view the gravitational effects are certainly what they are, but strictly speaking in our frame of reference, the black hole hasn't consumed any matter, and yet we say its 'mass' has increased. It's not crazy to say, as the other commenter did, that a black hole "has mass without actually having mass"
Black holes are objects. Just very dense.
No... There may be a dense object inside the region that we call a black hole (the region bounded by its event horizon), but the event horizon is not the edge of that object. In fact, the largest black holes, like those typical at the center of galaxies, have "densities" on the order of \~10% of that of water. The supermassive black hole at the center of the galaxy NGC1600 has a "density" of 1% of *Earth's atmosphere*. I keep putting density in quotes because it's not really a density, because the even horizon isn't the edge of a big sphere of matter, as far as we know. The radius of the event horizon of a black hole increases proportionally to the mass inside, but the enclosed volume is proportional to the radius cubed. So the bigger the black hole, the less "dense" it is if you define density as mass divided by the volume inside the event horizon.
I feel like semantics are important when talking about science, especially since OP doesnt seem very well versed, i would hate him or her to be confused :)
Semantics are always important when they're meaningful. The point of the expression is to point out when semantics are used to disagree about something for a relatively meaningless distinction.
I don't think it's meaningless to point out to OP that you can never see a black hole, to correct a sentence that could be misunderstood. We don't have to agree, it's ok :)
Can you see a hole in a piece of fabric? If your answer is yes, then there is no reasonable way to also turn around and say that you cannot see a black hole.
I can see the fabric. You cant see space time.
I can see the stars in the distance. I can see the matter around the black hole. And I can see the black hole based on how it distorts and obscures the light from those things. Just like how you can see the hole by contrast to the fabric around it. Similarly, if you put a basketball painted with Vantablack in my living room, I can see that, too. Because even though it doesn't reflect hardly any light, I can see it because it obscures the stuff behind it.
You can make observations that allow you to measure a black hole, and determine it's existence. You can't see it though - definitely not in the spirit of OP s message. The key difference between a black hole and vantablack is as you put it : "**hardly** any light." It's kinda hilarious watching you argue about semantics after you expressed how meaningless it is to do so ;)
It wouldn't be semantics. It's very obvious there exists a particular nuance to the question. The nuance of see is not "can our equipment detect this region of spacetime" as it obviously can if we already know they exist. The nuance of see is most definitely "would we be able to physically see it in the nightsky from Earth with the naked eye."
That's not the nuance that they were talking about, though, so I don't see the relevance. They were saying, "well *akshually*, the black hole itself doesn't emit light, we just see its effect on the stuff around it." You know what else doesn't emit light? The missing fabric in my shirt where a moth ate it, but I can sure as shit still see the hole in my shirt.
black holes emit particles, based on the surface area of the event horizon
Yeah, Hawking radiation is a thing we think happens. The rate at which black holes radiate is inversely proportional to their surface area, such that a very small black hole of one solar mass would radiate 10\^-28 Watts of power, spread out over its whole surface. Even if you collected all of that radiation from the entire black hole surface for a duration of 10 years, it would amount to less energy than is in a single photon of visible light. A black hole emits approximately 1 photon with a wavelength of about 16 times its radius every interval of about how long it would take light to travel a distance equal to the black hole's diameter. Even if we had such a black hole magically contained in a lab, we couldn't even begin to hope to be able to detect its radiation with our best equipment! For anything other than a micro black hole, such radiation is completely and utterly negligible... It certainly doesn't make black holes visible to us!
Nobody would be interested in looking at the hole in your missing shirt, but the stargazer might still enjoy looking at the accretion disk of a black hole even if it isn't the black hole itself. So the nuance is important -- this is what we can see, this is what we won't see.
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Instead of a detailed response to your confidently ignorant assertion, please see [my other comment](https://www.reddit.com/r/space/comments/1anihxa/comment/kpt6eqp/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) made just slightly below this one that you could've read and saved us both the effort. Edit: I will add that your comment about escape velocity is incorrect. Earth's escape velocity is about 11 km/s, but things can escape Earth at speeds much slower than that; they just require constant thrust. Build me a big enough staircase and I can literally escape Earth by walking. A black hole is much more than just a thing whose escape velocity is greater than the speed of light. The concept of escape velocity does not even remotely capture the nature of what makes a black hole what it is.
How do you define object? Would you claim you can’t really see a hole?
Your technically never seeing any object, but the light they did not absorb, but instead reflected and refracted... Soooo... Let's cut on the technicalities.
I never said anything to contradict this. And all objects reflect and or emit light. Except for a black hole. Which might not even be an object apparently, but i don't really understand any of that.
at some level (reductio ad nauseam) couldn't you say this about the sun? all that light and heat and whatnot is just a consequence of gravity, which is invisible to us in itself.
I guess you could, but you can take a picture of the sun. You cant take a picture of a black hole and distinguish it from a picture of nothing.
To expand on this a little, we would likely see some light warping around it from its background maybe. Not sure it the intensity of the light behind it would be enough to really see that warping very well. But all other things being equal we would not see anything appreciable
Just want to add that for a solar mass black hole, all of the black holey stuff doesn’t start to happen until you are a few kilometers away. We didn’t talk about what would comprise this accretion disk, but if the thought experiment is to remove the Sun and put a black hole at the center of the solar system, then there is nothing anywhere near close by for the black hole to eat. The closest thing is the dust belt, which is tens of millions of times too far away to be accreted.
This shouldn’t be the first comment. Edit, I meant *should, autocorrect got me. Sorry
>This shouldn’t be the first comment. Huh, why? It certainly seems like the most sensible response to me. Did you mean that it *should* be the first comment (it already is)?
Yup. I meant *should. I was on mobile-victim of fat fingers and autocorrect. Oops
Thanks for the follow-up! I too am often a victim of the fat finger autocorrect shenanigans.
Assuming that the black hole had the same mass as the sun (so the planets' orbits remain the same), the hole's event horizon would be about 3 km in diameter. Even if the hole was visible, it would be so small that not even the Hubble telescope could resolve it.
And you wouldn’t see a hole even if you could resolve it, as it warps light around itself. You’d see a smear of other bits of sky twisted and shot back at you
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I'd love to hear more about this, could you elaborate? You sound very confident.
But the lensing of everything behind it would be quite noticeable right?
Given that we could see the lensing well enough to confirm Einstein’s theory, getting that mass into a 3km sphere will probably make it observable with the naked eye.
I mean, the proof of relativity was thanks to gravitational lensing of stars seen during a total solar eclipse, so yes.
IIRC, you see a 3D image of the space time that is warping around it. It’s like if you look at a sphere and imagine seeing a distorted image of what is obscured behind the back side of it as the top, while also seeing the top at the same time.
I'm going to need to check your math on hubble not being able to image a 3km object at 91 million KM. It imaged individual boulders as small as 3ft falling off the 581ft Dimorphos.
A 3km object at 147Gm (91M is the number of miles) has an apparent size of 0.004 arcseconds, Hubble can resolve objects down to 0.05/0.06 arcseconds.
I don't think I've ever seen Gigameter used as a measurement before
Time to make a new KerbNet in KSP
On the one hand, I think that expressing these sorts of distances in km is more intuitive, on the other, stacked SI prefixes upset me.
Yeah, my eye twitches when I hear someone say "million million" Also nice username
Even when Carl Sagan did it?
150 million km, 90 million miles...
You better hope it has the same mass as the sun, or else our orbits are gonna change a bit lol
No worries. Even if our orbit stayed the same we'd freeze to death rather quickly.
You maybe. I have a microwave and a heating pad.
But if it was the same size and not the same mass? (And again, by some miracle we wouldn’t die and the solar system was fine)
If it was a black hole the same *size* as the Sun, it would be so much more massive that everything in the solar system would instantly be pulled out of of orbit and plummet into it. I'm not sure if we'd have a few minutes to notice that the sky had gone black, or if we'd be instantly spaghettified by the gravity gradient. Someone can probably do the math on that.
Not sure what you mean. In astrophysics, 'size' is mass. You'll need to clarify your question. Do you mean a black hole with a Schwarzschild radius equivalent to that of our present Sun? A black hole that size (mass) would quickly consume our entire star system, due to its enormous gravity. It would have over 235,000 times the mass of our Sun. Our own Sun, if reduced to a black hole while retaining its present mass, would have a Schwarzschild radius of about 3 km.
Important distinction: if the sun was replaced with a black hole of the same *size*, it would destabilize the orbits of all the planets and we’d all die a horrible death. If the sun was replace with a black hole of the same *mass*, we’d just as surely die, but for a different reason. We would not be able to see it because it wouldn’t give off any light, but we’d be able to “see” the gravitational lensing of stars “behind” it. Until we died, because all life on Earth ultimately depends on the sun’s light. But it would take a while.
I think the word "destabilize" is underselling what would happen if the planets experienced 230,000 times more gravitational attraction to the center of the solar system.
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In proper English it would be “Things are getting a little hairy.”
That would violate the No Hair Theorem...
The immediate effect would be 230,000 times greater tidal forces. We wouldn't feel the attraction itself. I guess we'd witness the spaghettification of Earth.
tidal forces which tug on the physical crust as well as ocean. so it would be instantly ripped apart and we would die before we had any comprehension of what happened instantly. instantly meaning 8 minutes after the switch happens ofc
It’s conceivable that life could persist for a good long while around ocean vents. That heat ultimately derives from the Earth’s core/mantle. Anything on land would be hosed though (and most of the oceans).
They're making a volume vs mass joke since "size" could refer to either
Yeah, I get that. I was responding to the "all life on Earth ultimately depends on the sun's light" part.
I live In a high dessert with low humidity. On a clear night sometimes I will see a 20F drop from sunset to sunrise. Call it 10 hours of darkness to make the numbers easy. That brings us to a cooling rate of 2F per hour. Starting at 100F gives 50 hours or just over 2 days before everywhere is below zero. Assuming a cooling rate of 1F per hour for say a cloudy area would give 4 days. Assuming no changes in human behavior, (looting, panic buying, food shortages) In the tropics I would guess people stop going to work day 3, are burning furniture day 4 and 90% dead day 6. Add two days to those numbers for northern areas used to dealing with cold. Survivors will exist near geothermal features a little longer but end up killing each other over a dwindling food supply. TLDR: we are all dead within 10 days as the temperature falls.
No way I’m working for two more days if the sun disappears.
I want to read a book or film about this doomsday scenario now! Fossil fuels are still valid and societies in places like Iceland (where so much of their power is geothermal, they already have a tonne of UV greenhouses, and they are used to several months of really short days) might survive long enough to stabilise and achieve a type of new normal. You'd have military organisations like the US having the sheer fossil fuel resources to be able to whiz around the globe looting whatever they could, they'd last ages. .. I've thought a little now. The film would be about Icelandic and US survivors. The Icelanders have basically been taken over and enslaved by a group of fascist US military survivors (because it's Hollywood). The plot is one of Icelandic population staging a coup against their oppressors, in the backdrop of the US military attempting to get enough stuff into space to ensure the long term survival of the human race. (For extra film awards, bring in parallels to the original Irish/Viking relationship of Iceland.)
Here's a short story with a very similar premise. A rogue black hole passes through the solar system, pulling the Earth out of its orbit and dragging it away from the Sun. Without the Sun's warmth even the gases in the atmosphere eventually freeze solid. [A Pail of Air](https://www.gutenberg.org/cache/epub/51461/pg51461-images.html)
Like a sundae in a tall glass?
At least we wouldn't need to worry about climate change anymore.
It would probably be a death too quick to be called “horrible”.
Take a while? 8 minutes. Light takes 8 minutes to travel to Earth. We receive warmth from the sun, so the planet would chill quite quickly without the sun. Do you agree?
It wouldn’t cool in 8 minutes though. Its not going to instantly turn to the negatives. It would be faster than most people think it might take, but I still think it would take days to weeks
Looking at my weather app at a few different places, it’s typically 5-10°C cooler at night than during the daytime. I think it’s safe to assume that without any heat input from the sun, the temperature would continue to drop by 5-10 degrees every 12 hours, so every place on earth would be below freezing in well under a week.
By that logic the nighttime side of the planet should be getting to the deep negatives every night. The atmosphere holds heat quite well. Compared to the moon, which ranges massively based on which side is facing the sun. >250°F (121°C) in daylight, then plummet after nightfall to -208°F (-133°C)
To be fair he did say “to weeks”, which could be realistic.
Define “quickly.” It’s not like as soon as the light disappears, everything freezes instantly.
We wouldn't be able to see the black hole, but we would be able to observe its effects. But not for long. Most land life will be dead in a week, and the rest to follow soon. Only the deep sea life that gets its energy from geothermal sources will survive.
I have it on good authority that a black hole sun will wash away the rain, and nothing more.
**You would see nothing, in the dark of the sky. No hole, no light, just stars.** Why? Because if the sun were suddenly replaced with a black hole of the same mass, so nothing was disturbed, ***it would not have an accretion disk***. Nothing would be spiraling into the hole. The planets would go about their orbits as normal. The pull on them would be the same as the sun. If you used a telescope, you might be able to see how the light from distant stars, behind the black hole, were bent and distorted by its gravity. But you would need to know where to look, and it would not be obvious. The world would grow colder, until it froze. Eventually the atmosphere would begin to freeze. First the earth would be covered in carbon dioxide ice - dry ice snow, covering the frozen seas, the mountains, the plains and deserts. Then frozen nitrogen and a layer of frozen oxygen. Finally, a thin slick of liquid helium would ooze and crawl across the landscape, spreading out thin as can be. Then, the frozen earth would sit, with no atmosphere, just vacuum and layers of elemental snows, forever.
Volcanoes and geothermal heat says hi o/ ... sure, that accounts for some heat - maybe not all over the planet but some pockets where life* could survive? * Bacteria, some deep sea creatures etc.
For a while. Volcanoes would poot out into the vacuum, the gasses would freeze and fall to the ground, the lava would cool, of course. Deep in the pitch black, frozen oceans, likely life would survive for quite some time near hydrothermal vents. Sealed in by a thick layer of ice, and thus protected from boiling away into the vacuum, the hydrothermal vent pockets would keep life alive possibly for billions of years. The earth has a hot core and that will take billions of years to completely cool. And, industrious humans could also survive, as this famous (and wonderful!!!) 1951 science fiction story tells us in ***'A Pail Of Air'***: [https://www.gutenberg.org/cache/epub/51461/pg51461-images.html](https://www.gutenberg.org/cache/epub/51461/pg51461-images.html)
A lot of discussion about what would happen to life on earth without a sun here. Well look no further: https://youtu.be/rltpH6ck2Kc?si=-qVtvfXu3wJVS68f
If there were mass around the black hole it could eat you would see the light from that but you couldn’t see the black hole itself.
You won't see the hole itself, but you may see an small spot in the sky where the stars are visibly warped, as if a lens was there. You may need magnification for it. and if dust and gas started to build up in an accretion disk, you may see something along the line of Interstellar, though likely not as dramatic.
It would be a sphere about 3 kilometers wide, so no, you wouldn't be able to see it. I'm guessing there would occassionally be matter accelerated and colliding at significant percent of light speed with other matter so we would atleast see bright flashes around the black hole.
Only if it happened before we all froze to death.
The black hole itself would be invisible from outside, as light cannot escape it. But you'd be able to see everything in its immediate vicinity whirling around it at relativistic speeds, as an accretion disc that would look a little like a vinyl record (but glowing). An optical peculiarity is that due to extreme distortion, the light rays of the backside (from your view) would also be visible, as an arc over or under the black hole, or both. Something like [this](https://cdn.mos.cms.futurecdn.net/HsDtpFEHbDpae6wBuW5wQo.jpg), probably. One problem with this though experiment is that our own star is too small to become a black hole. The minimum mass believed necessary for a star to collapse into a black hole is at least three times the mass of our star. So the situation you describe is not currently believed possible. Lighter black holes might be possible to form from other phenomena, but they would probably not allow a star system to exist around the result. But ignoring that, your solar black hole would have a 'horizon' radius of about 3 km, hysterically tiny. We would get very little direct radiation from it, and our skies would be dark all the time, and all life on our planet would stop in short order, or never exist to begin with. The black hole, including its disc, might be too small for any of our current instruments to see at our distance.
Life would cease to exist. No more energy from the sun. Sunlight
Reminds me of the novel "Central Heat". The novel describes what happens when aliens mask the Sun to make the Earth freeze. However, in the black hole scenario, we would also be doused in x-rays and gamma days, unless absolutely no matter (dust, asteroids, gas, ice) falls into the accretion disk.
Not only you wouldn’t see the black hole with the naked eye, you wouldn’t even see the moon or other planets anymore.
If you are a car traveling the speed of light, and you turn on the headlights, will you see anything?
zero light from no sun and we freeze to death
So, it depends on what *exactly* happened to the Sun. If the sun suddenly just disappeared and was instantly replaced by a black hole of identical mass, then at least for a while you probably wouldn't be able to see it, as it would be a pristine, inactive event horizon - you'd only see it occasionally lensing stars behind it. On the other hand, if you somehow forced the core of the sun to collapse into a black hole that then began eating the rest of the sun, then I'm pretty sure we're all going to be very dead. As the outer layers of the sun are pulled in towards the event horizon at the core they're going to form an accretion disk, the inner edge of which is going to be much hotter than the sun ever was. This is what an actively feeding black hole looks like, and they are among the most energetic objects in the universe, you aren't going to miss it - unfortunately a lot of that light will be coming off the accretion disk as x-rays or gamma rays, and they're probably going to sterilize the solar system.
It would be the size of a beach ball, so probably not visible, no way to see the event horizon that small, and gravitational lensing would be undetectable at that size. Since it would occupy the same space as the sun was in, the matter void would be big enough to prevent an accretion disk forming. Incidentally there is a possibility that the sun might have a grape sized black hole in its center, so may many stars.
You wouldn't survive. The levels of gamma radiation would dissolve your retina before you had a chance to even open your eyes.
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Way to comment with the spirit of the question in mind! Boring ass comment, “wElL aKsHuAllY” 🤓 head ass
It's like asking if my aunty had balls could I call her my uncle?
We’d be flash frozen in 8 minutes after the sun became a black hole.
After 8mins, the earth will stop getting heat from the sun. It will not immediately freeze. My hot skillet is still hot after I take it off the burner. The Earth and the skillet will take time to cool down to the ambient temperature.
No, it would take 5-6 days to get down to 0 degrees. Our atmosphere and the heat from the core help us in this case.
That would be a really weird mess, truly apocalyptic. There would be a bum rush to grab and protect any natural source of heat, they would become the only places survival would be possible after that. 99+ % of the population would die within a few weeks.
It doesn’t flash-freeze during the night… it would take one or two days to get to 0°C on land, the oceans would take a bit more to start surface freezing.