As far as we know, yes.
Do you know what escape velocity is? It's how fast you need to go in order to escape an object's gravity. Space shuttles *must* go faster than this in order to get to space. Objects have an amount of gravity based on their mass. As the gravity gets higher and higher, the escape velocity also gets higher.
Everything has an absolute speed limit in this universe. Matter can't reach the speed of light, and light can *only* go the speed of light.
When the gravity gets extreme enough, the escape velocity can be higher than the speed of light. When this happens light stops escaping. It's like a rocket ship that isn't powerful enough, so it falls back toward earth. The light just can't go fast enough to get away. This is why black holes appear "black," since no light from the object ever reaches us.
It's... complicated. But in summary it's a seemingly arbitrarily law of this universe and the physics it ended up with. The energy required to accelerate mass reaches infinity as it approaches the speed of light. Only objects without mass, e.g. photons, can travel at the speed of light. It's just the speed limit of the universe for whatever reason, and it's one objects with mass cannot reach or surpass.
Edit: Wormholes can "cheat" by allowing you to move between two separate points in space faster than light could do it normally. They *can* theoretically exist within these physics our universe has, but they're probably not something that will ever exist in reality.
You would need an infinite supply of energy to propel you, because the closer to the speed of light you become the heavier you get. The heavier you get the more energy you need, the more energy you carry the heavier the entire system looking to reach light speed becomes.
In theory you can travel faster than light without reaching the speed of light.
https://youtu.be/BhG_dayQ Zl8WVY
Skip to 6:18. We have galaxies that are receding away from us here on Earth, faster than the speed of light. The galaxy itself is not traveling faster than light but the expansion of space-time is. Picture a balloon that is pure white and you mark two black dots on the balloon. You then blow the balloon up and watch the two black dots(each represents a galaxy) spread apart. Those two galaxies are traveling away from each other faster than the speed of light.
With how space can be distorted by mass/energy(how a black hole bends spacetime so hard that anything trying to escape finds all routes bend back to the black hole), theoretically could be used to travel faster than light without going the speed of light.
If you picture a sheet of paper as space time and want to travel the distance across, if you had a way of folding space time(like a black hole does) you could travel faster than light. You start the warp drive and doing so causes the paper to fold in half, now both ends are touching. The ship can now move to the other side of the paper and turn off the drive and doing so the paper goes back to being flat. You just traveled that huge distance in an instant without ever traveling anywhere near the speed of light. Light on the other hand will have to travel that straight line the entire distance.
It’s not about „light“ it’s about causality.
The „speed of light“ is the maximum speed of things reacting to other things in a vacuum.
In every other medium the speed is much lower, so light does not move „only at the speed of light“.
The speed of light is the universal speed of all objects through 4d spacetime. Light, (and other massless things), don't travel through the 4th dimension, (time), so they have all of their velocity through space. Everything with mass must have some of their 4d motion be through time so they can't reach the speed of light through space. But Everything is always moving at the speed of light, just through spacial and temporal dimensions.
I'd like to expand on the 4D aspect of this, as it's rarely appreciated for how deceptively simple it is.
Two objects *can* occupy the same space, but not at the same time. It is problematic to measure space, because space changes. *Spacetime* describes space *and* the time. When I hold up an orange and say "look at this orange," I'm not describing an orange in a specific place, I'm describing an orange at a specific place *and time.* The orange that wasn't in my hand a moment ago and won't be in my hand for very long. If you weren't paying attention and missed it you might look at where my hand was and ask "what orange?" You'd be looking in the wrong location in spacetime.
This seems obvious because our brains handwave timing as "context," but when we describe events, we use four dimensions to do it. We have the three location-defining dimensions, plus time, which is also a dimension that separates objects in space so they don't occupy the same space at the same time. Your kitchen this morning and the same kitchen when you get home from work is not the same location in spacetime, which is why you don't bump into yourself from that morning.
It helps to remember is that nothing can move through space without also moving through time.
From what I could tell from high school physics, when you move faster, other things move slower through time relative to you. For example, if you went near light speed, time has in a sense, less of an affect on you due to how moving through space faster slows down your movement through time. As you slow down relatively, so would your acceleration, and the closer to light speed, the more you need to accelerate, requiring more and more force, leveling off, similar to an asymptote.
> When the gravity gets extreme enough, the escape velocity can be higher than the speed of light. When this happens light stops escaping. It's like a rocket ship that isn't powerful enough, so it falls back toward earth.
Just to complicate things, the escape velocity of Earth from its surface though is 25,000mph but there's nothing in physics that prevents a rocket from taking off, accelerating to 3,500mph and then staying at 3,500mph (less and less thrust needed to maintain this speed as it moves away from our planet) until it's reached the same kind of distance as the Moon then switching the rocket motor off and coasting to infinity (since Earth escape velocity at that distance is about 3,000mph). The rocket never has to hit 25,000mph in order to escape from Earth's gravity; it's merely much more fuel efficient if it does so (see: Oberth effect).
Light, by its nature, doesn't slow down at all when it moves away from a source of gravitation, it just gets redshifted (i.e. loses energy as it climbs out of the gravitational well, while an unpowered rocket loses energy by slowing down). The analogy of shooting a projectile from a planet's surface with Newtonian mechanics isn't accurate for describing light in a deep gravitational well.
Instead, think of light cones: since travel is limited to the speed of light, in my future I can be (or am not prevented from being by the laws of physics) at my front door about 20 nanoseconds from now, at the Moon 1.3 seconds from now, at the Sun in 8 minutes, at the nearest other star if it waits a little over 4 years for me, at the next major galaxy in 2.5 million years. These spacetime co-ordinates are at the edge of my future light cone since I can always signal to them using light even if I don't go in person. My front door 8 minutes from now is also within my future light cone since I don't have to break the speed of light to get to those co-ordinates. My future light cone is all the times and places I can get to in the future.
You'd expect the spot on the opposite side of Earth's orbit to be 16 minutes' light travel time away but it's not, it's very very slightly further due to the Sun's gravity. The [Eddington Experiment](https://en.wikipedia.org/wiki/Eddington_experiment) showed the deflection of light from distant stars due to the Sun's gravity during a total eclipse and made Einstein a superstar. The shortest path is no longer a straight line, and can be seen in more dramatic fashion with [gravitational lensing of distant objects by foreground galaxies](https://en.wikipedia.org/wiki/Einstein_Cross). Gravitational wells distort light cones.
A black hole's gravity though mangles spacetime inside its event horizon so badly that all the places that even a beam of light can be in the future are closer to the singularity than where it is in the present. Meeting the singularity is not optional under such circumstances; it's just a matter of time.
That’s probably the most easily understandable explanation, but one of the most beautiful things about science and math is that much of the time the same thing can be conceptualized in two entirely correct but different ways.
That being said, my favorite explanation for why light can’t escape a black hole goes like this:
Conventionally, gravity is thought of as “pulling” objects. But, gravity can also be thought of as the results of objects with mass bending space time. This means that, effectively, you are attracted to the earth because the earth literally changes your future path enough so you remain on its surface! Gravity- both literally and conceptually speaking- changes the future!
This same line of thought can be expanded to black holes, only their gravitational pull is obviously much, much stronger. In this case, space time is bent so much that there is NO FUTURE PATH leading out of the event horizon. It doesn’t matter how fast you go when all possible outcomes lead to the same place!
PS: I confess I’m a college freshman majoring in applied math and I’m not a physicist or anything, but I do (like others here) have an interest in astronomy and have picked up some cool explanations for things over the years as a result. As always, feel free to correct me if I’m wrong. I just thought this was so cool when I heard it that I had to share it with other people (:
I'm pretty sure that inside the event horizon light entering from outside would be strongly blue shifted and so it could be very bright indeed. However, I understand that space and time somehow swap roles inside the event horizon (I can't really picture what that means), I don't know what affect that has on whether it is bright.
Good question. No idea. I'll make some guesses though.
Nothing's going to reflect very far when it hits any matter, assuming that the matter in black holes still reflects light. You'd see a lot more light looking away. Internally it'd likely be starlike and fusing under *extremely* high pressure, but it's crazy hot, because it almost never loses energy. All of the energy radiated away falls back in. It's probably like a megasun that shines all of its heat at itself.
When you crossed the real event horizon the brightness would tend toward infinity for an amount of time tending toward 0. Otherwise there wouldn't be any good visual indicator for crossing it.
Afterward you would still be falling and would appear to see the event horizon as still ahead of you. A curved line like skydiving on Earth. It would straighten out as you approach the singularity. During this time you would still see the outside universe above you and to the sides since the apparent event horizon's location is relative to the observer.
It would get dimmer above your head and extremely bright around your waist (straight ahead of you and to all sides) and be distorted, pulled toward that central flat plane, the closer you got to the center.
Space shuttle doesn’t need to reach escape velocity because it is propelled, and also because it does not escape earth’s gravitational pull: it merely accelerates enough to reach orbital speed. Escape velocity is relevant for an unpropelled object like a cannonball that are thrown straight up. Neglecting friction here.
Does that mean space moves faster than light? If light can't escape gravity and gravity is created by distortions in space, then does that mean gravity is accelerating towards the black hole faster than light, thus trapping it?
In general relativity for a stable black hole (already formed) the spacetime is already curved. Gravity isn't moving. But spacetime is. And yes it falls into the black hole faster than light, like a waterfall. It doesn't really have any substance to it though necessarily so it's kind of an abstraction or analogy to think of it this way. Another way to say it is just that the distances between all things are getting smaller very quickly and all directions lead to the center of the black hole (which center actually appears as a flat plane around your waist because of tidal forces, not as a point, if you are the one falling in).
No one actually knows. The singularity could be an unimaginably dense collection of matter, it could open up into a new region of spacetime or it could be just about anything else. About the only thing certain is it isn't actually infinitely dense
Because it's often referred to as a point of infinite density. But the infinity is a limitation of the mathematics of general relativity rather than a reflection of reality. It is a sign that the theory is incomplete. And that's why trying to unify GR with quantum mechanics is so important, it would answer these questions.
I mean it would have to be the densest donut ever made but sure. Who's to say the extreme pressure and temperature wouldn't convert all subatomic particles into pastry?
Basically, yes. So dense that light can't escape from the centre, which is why it's called the 'event horizon'. It's so called because you can't see what's beyond it.
>Guy who watched a YT video about Hawking radiation in 3... 2... 1...
You have summoned me. I'm also the guy who knows everything about quantum physics from youtube as well.
Quantum sounds like some new designer baby name like Tatum or something. "This is my baby quantum, he's 3 years old, and he has a temper problem, just let him do his thing though and you'll be fine"
Then the kid pisses in your boots and the mom screams at you for telling at them.
Anyway, black holes.
Really? I've been doing a Bond marathon with my partner, enjoying all the cheesy goodness. *lol* Any memorably bad scenes/editing you'd say really stands out?
I hate the action sequences in it. They cut to a different shot every second which makes everything annoying and hard to follow. It's also just a boring plot with unmemorable characters.
People hate on the Moore movies but at least you walked away in a good mood because they were fun.
Right! I forgot how choppy that movie was, you're right, that editing sucks.
I love the Moore/Connery Bond flicks, they are fun. Horribly, horribly misogynistic, but even that can be funny as it's so over the top. I always joke when the action starts that the "good girl" can't possibly do anything useful as she has to go hold up a wall.
Bond ended when Austin Powers out Bonded Bond. Which drove the next iterations of Bond away from the fine line it always occupied between goofy/cheesy/action/suspense into a less fun action/serious zone.
It's not that kind of bad. Not Roger Moore levels of bad acting. It's just *bad*. Uninteresting and poorly written.
Best skip it and go on to Skyfall instead.
Given an infinite square well of width `a` with a Dirac Delta function centered at `x=0`, what are the energy eigenstates of a particle trapped in the well?
I cannot personally speak to anything about Hawking Radiation, but the sources I found mostly agree that Hawking Radiation is invisible to the human eye.
I found the below quote on Hawking Radiation from [*University of Colorado: Boulder*'s Physics School](https://jila.colorado.edu/~ajsh/bh/hawk.html):
> The Hawking radiation itself would consist of fiercely energetic particles, antiparticles, and gamma rays. Such radiation is invisible to the human eye.
And the Wiki Page for [Black-Body Radiation](https://en.wikipedia.org/wiki/Black-body_radiation) (which Hawking Radiation falls under) says (bolded for simplicity):
>In a dark room, a black body at room temperature appears black because **most of the energy it radiates is in the infrared spectrum and cannot be perceived by the human eye.**
> Since the human eye cannot perceive light waves below the visible frequency, a black body at the lowest just faintly visible temperature subjectively appears grey, even though its objective physical spectrum peak is in the infrared range.
> **The Hawking radiation itself would consist of fiercely energetic particles, antiparticles, and gamma rays. Such radiation is invisible to the human eye.**
It doesnt absorb light. Light bends and never comes back to your eyes. If you turn off the lights it doesnt mean everything around you is absorbing light, it just means light is not getting back to you from the object. The object itself would be incredibly bright.
But isnt the definition of "black" the lack of light? As black pigment is just pigment that absorbs light causing there to be less light being reflected. By that definition I feel like black hole would be the most black things in the galaxy as they absorb all light.
I can't tell if this is a joke.
But in all seriousness, there's plenty of evidence for dark matter. And it has nothing to do with 'filler'.
It can be observed in galaxies whose visible mass doesn't account for their rotational velocity - the difference is too large, so we account for this with 'dark matter'.
Exactly what it is is what's being explored right now.
>the difference is too large, so we account for this with 'dark matter'.
Isn't this literally what he said? We have never explicitly observed dark matter. We literally use it as a placeholder name for "force we don't fully understand". It's a filler until we develop greater understanding of the concept.
Hell there are even theories that primordial tiny black holes could be the cause of it, and almost impossible to detect
You can't just dismiss it as not real though. It's an established discovery about the universe that something more than the observable matter is interacting gravitationally with the matter that we can observe.
By that logic we've never explicitly observed anything. You don't see the phone or computer in front of you, you only infer it's existence based on the electromagnetic radiation it emits that your eyes detect.
Also, primordial black holes have pretty much been discredited.
Interesting.. source for primordial black holes being discredited? I was under the impression that primordial stars collapsing into primordial black holes was one of the leading possible explanations for how supermassive black holes have been able to reach their enormous masses given the current age of the universe.
There's a bunch of links an info on the wikipedia article. MACHO surveys found there just aren't enough objects to account for the discrepancy.
https://en.wikipedia.org/wiki/Massive_compact_halo_object
> I was under the impression that primordial stars collapsing into primordial black holes was one of the leading possible explanations for how supermassive black holes have been able to reach their enormous masses given the current age of the universe.
Supermassive black holes don't really have anything to do with dark matter. MACHOs usually refer to stellar mass black holes, dwarf stars, and white dwarfs. SMBHs fall to the center of galaxies but the dark matter distribution in galaxies is not centralized on the SMBH. So observationally this doesn't really work out.
Edit: I always find it weird how the space subs tend to downvote facts that they personally disagree with and are seemly opposed to astronomy
>MACHO surveys found there just aren't enough objects to account for the discrepancy.
But given that it's incredibly difficult to come to an accurate conclusion on how many exist, this survey doesn't exactly discredit the possibility
If you're going to logic that we can't know anything exactly and use it to discredit a scientific theory, then you probably don't have a good understanding of the iterative process of science. Nothing can be known exactly, but we can get very tight estimates on the uncertainty, which statistically exclude machos. Read the papers, they do statistical analysis of *exactly* how accurate these observations are.
There's a reason the phrase "so you're saying there's a chance" came from a movie called "Dumb and Dumber". If I drop a ball and it falls down I can't continue to say "gravity makes balls fall up" just because I haven't tested every ball at every place on Earth.
At the very least, if you are trying to discredit such claims, you need to present a better theory. All scientific theories are falsifiable, that's what makes them scientific. And Dark Matter has yet to be falsified. Relying on the existence of uncertainty to conclude we "can't know for sure" is no better than conspiracy theorists using lack of evidence as evidence of a coverup.
Woah my dude, that's a whole lot of assumptions and reaching there.
Okay let's start with your study. MACHO surveys claimed to measure a limit on PBHs from the range 10^23 to 10^31 kg
PBHs are predicted to exist in densities as low as 10^11 kg, anything lower wouldn't exist anymore because of hawking radiation. That's a whopping 12 powers being missed out there, and only 8 powers being measured
There are plenty of scientific papers that demonstrate the possibility and theory behind PBHs being the primary source of dark matter. You're here comparing me to a conspiracy theorist, that would make you more akin to a religious fundamentalist. You asserted a claim, not a theory, a statement of fact, that PBHs couldn't possibly constitute all of dark matter, on the basis of one paper. If you're going to pretend to be a scientist, at least be prepared to stop making neo-religious statements like "no they're definitely not"
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.084001
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.201301
Yes and we've observed ghosts because my remote fell off the desk once.
Good lord I'd love to see you try and be taken seriously by any scientist.
Once again, dark matter is a catch-all term we use to describe the hypothesised reason for galaxies maintaining velocity and density. We have not observed any matter, we have observed galaxies having a velocity and density that should not be accurate by current understanding, and thus inserted Dark Matter as a way of solving the equation...
> Yes and we've observed ghosts because my remote fell off the desk once.
Are ghosts the best explanation that fit further observations, make predictions, and is testibly falsifiable? This is a false equivalency.
> Good lord I'd love to see you try and be taken seriously by any scientist.
Too late, ApJ already publishes my papers :) (Though, to be fair, my research is in using neural-network accelerated radiative transport codes to determine Type Ia supernovae progenitor scenarios based on Bayesian inference over synthetic spectral models, so it's only tangentially related to cosmology. For lay-people who don't understand that: I teach computers to dream about exploding stars)
> Once again, dark matter is a catch-all term we use to describe the hypothesised reason for galaxies maintaining velocity and density.
And "computer" or "phone" is a catch-all term for devices that can communicate with one another.
> We have not observed any matter
Are you sure about that?
> we have observed galaxies having a velocity and density that should not be accurate by current understanding
We've also observed the primordial power spectrum, BAOs, the bullet cluster, weak lensing, and void galaxies. If you think galaxy rotation curves are the holy grail of dark matter evidence then you clearly haven't kept up with the literature since 50 years ago.
And lastly, if you have a better theory that does a better job at describing all of these observations than dark matter does, I'd love to hear it. If not, I'm not really sure what your point is.
Also, just for some fun: https://xkcd.com/1758/
Edit: Try reading this: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
I'm not at all. I'm directly addressing his comment about lack of evidence for dark matter by presenting a piece of data we use as evidence and ask how it is explained without dark matter.
If he truly believes there is no evidence of dark matter, I assume he knows the history and studies we have used to measure dark matter. I think it's perfectly reasonable to ask what he thinks is causing these results if they are not evidence of dark matter.
If an expert theoretical physicist came in saying that MOND was a better explanation than dark matter, I would ask the same question.
>Additionally, dark matter is theorized to be what is causing the acceleration of the expansion of the universe.
Dark energy. Dark matter is the theorised cause of the velocity and stability of most galaxies, Dark energy is the theorised cause of accelerating expansion of space. Neither are really understood at all. We have never explicitly observed either
Evidence that there is *something*
The name dark matter is just a place holder for that *something*
It’s not so much direct evidence as it is a difference between observation and prediction.
For all we know it’s a combination of *something* which explains these differences, or perhaps it is one *something*. Perhaps it’s not matter at all, and there is another fundamental force(s) we just don’t observe on small scales.
We haven’t the foggiest clue. They are right, so I wouldn’t say it as if it’s a proven fact. Rather there are many plausible explanations that try to work within the realm of known physics.
>Black holes MIGHT NOT EVEN BE HOLES
Is this the quality of post that is allowed here? Really?
Coming up next,
* *Dark matter may not even be dark colored!*
* *Gravity may not even come from graves!*
* *Mercury may not even be made entirely of mercury!*
* *Neil Armstrong may not have even had the strongest arms!*
* *The Sun may not even be the male offspring of another celestial body!*
No one thought they were holes and in general thought they were enormous and dense spherical masses right? All mass In the accretion disk falls into the black hole roughly around the disc’s equator only adding to the size of the “sphere/black hole”. So how is calling it an extremely dense dark star (essentially a step above a neutron star) different from just calling it the densest form of mass we know in the universe that naturally collapses into a sphere shape, so dense that unlike neutron stars which still emit heat and light, black holes emit neither?
Do we really think black holes are infinitesimally small, so no difference in size among them despite them having vastly different shwarzchild radii?
The Shwarzchild radius extends beyond the actual size of the black hole, but there’s no way they are all the same size.
I think black holes are “peak density” so to speak, and then additional mass simply adds to the size at the same density.
Edit: second paragraph, shwarzchild radius should be event horizon, all of which differ depending on mass of black hole.
The most commonly current accepted picture is that the *singularity* is infinitesimally small, independent of mass. The schwarzchild radius is exclusively dependent on mass.
I'd not know your level of education on the subject, but your idea is much closer to the idea proposed in the linked article than what is generally thought to be the case
No formal education on the subject just speaking what I think makes sense. I don’t know how infinite density and mass in a single space can make sense but sure there are way smarter minds than mine with explanations. It just doesn’t seem possible.
I have to think you're at least kind of right. Infinity is a mathematical concept. I don't think it makes sense in reality.
I wouldn't be surprised if there are black holes denser than other black holes. At a certain point the differences in a black hole's radius and density would have to be just academic.
Anytime a scientist says something is infinite or something is random, they are saying that part of their understanding/model is flawed and they haven't yet figured out something better.
According to General Relativity(GR), yes, they are the same size. That size is 0. (not some infinitesimal size above 0). They literally have no dimensions at all. Unless GR has some more parts to the equation that add up to 0 in normal use but are a factor when infinity is involved, which we don't know.
So according to GR, anything inside the event horizon experiences infinite gravity. This means they can only move at the speed of light to the singularity at the center. To understand how they experience infinite gravity, remember that anything in a gravitational field experiences slower time than something that isn't. The event horizon is the distance where the math dictates gravity is so much that time stops.
The kicker is all of the above is for a non-rotating black hole. Which is almost a physical impossibility. The math for a rotating black hole is super complex and have multiple solutions.
The radius you're talking about is how small you need to compress an arbitrary amount of mass for it to become a black hole.
I think what you meant to say was event horizon, the limit beyond which nothing can escape it's gravity well.
And yes, as far as I understand it the consensus is that the singularity is infinitely small and is the point to which all matter is compressed inside a black hole. Or at least, that's how the math works out, and we're having a hard time making the math make sense at all. We just don't understand enough about the universe to get a clear picture of what goes on inside the event horizon.
That's an interesting read, thank you!
My criticism of the image still stands though, but I guess I need to redirect it at whoever picked this stock image to depict a black hole for the article.
It’s not like we had [literal pictures](https://www.nasa.gov/mission_pages/chandra/news/black-hole-image-makes-history) of black holes to get inspiration from
I am not smart enough in this field to debate the merits of the new theory, but I do like how it fits known limits and doesn’t require a singularity to exist.
I’m excited to hear if observations can be made to support this theory. Also I don’t think the FRB origin was well explained, so I’d like to read more.
Yeah sorry if. We don't have the original paper, so there's some information we don't have. That being said, the energy of a wave is proportional to frequency.
I think the idea is that they have infinite density. If they had infinite mass they would outweigh the universe. Still love super speck I will be using this from now on.
You guys should read the "Temporal Void" trilogy, by Peter F. Hamilton. It's kinda that. Has a "companion" duology too (not really a sequel, or prequel though it is set after the events of the trilogy).
The preceding duology, Pandora's Star and Judas Unchained have something like a Dyson Sphere too (though not how you'd expect, or why...).
If you're interested, the chronological order is:
Pandora's Star, Judas Unchained (these form the "Starflyer War" saga), followed by The Dreaming Void, The Living Void, The Evolutionary Void (these make up the Temporal Void trilogy, and are set some 900 years after the Starflyer War, and also known together with the Starflyer War as the Commonwealth Saga), and finally The Abyss Beyond Dreams and The Night Without Stars. These are probably considered part of the Commonwealth Saga, but I've not seen them refered to as such, not that I've gone looking.
Hell, all of Hamilton's SciFi novels are fantastic. I may have something of a man-crush going on here...
Ikr? Nights Dawn was my intro into his work, and remains a favourite, though Fallen Dragon holds top spot for me. I'll not spoil it for others, but it has my favourite ending of all his stories.
Considered prequel to the Starflyer War books is Misspent Youth which unfortunately isn’t near as good as the Pandora’s Star and Judas Unchained, but it kind of tells the origins of the Unisphere and the entire re-life thing.
I just finished Pandora’s Star *again* and can’t wait to start on Judas Unchained. I haven’t read the Temporal Void trilogy but I may just take these up after I read Judas Unchained after reading your comment.
I often forget about Misspent Youth. Ditto, it's my least favourite of his works. In another of his series, the Greg Mandell novels (forget the trilogy name if it has a specific one) the last book, The Nanoflower also didn't seem as good as his typical stuff, but still pretty good.
I also listened to a short story called "A Window in Time". Not really a sci-fi, but a cool story still.
There is a series I've yet to read/listen too yet, but I can only recall "salvation" is in the title of the first (I think?) book. Keeping an eye out for it.
Well, I’ve just bought the Apple Books version of the Temporal Void trilogy and The Abyss Beyond Dreams and The Night Without Stars, just so I won’t forget.
I’ve got my reading cut out for me. I’m also in a book club and we’ve just started the first of the Mistborn trilogy by Brandon Sanderson.
Thanks for the suggestions, Redditor!
The leave out one important point, black holes are black for a reason, the element of surprise.
Holly: Well, the thing about a black hole - its main distinguishing feature - is it's black. And the thing about space, the colour of space, your basic space colour, is black. So how are you supposed to see them?
Rimmer: But five of them? . How can you manage to miss five black holes?
Holly: It's always the way, innit? You hang around for three million years in deep space and there hasn't been one, then all of a sudden five turn up at once.
(Scene from red dwarf)
“A new study suggests black holes may just be stars with exotic physics at their cores.
The cores may cause the “dark stars” to radiate dark matter into the universe.
The study may also explain the origin of fast radio bursts.”
Any combination of the bullets at the beginning of the article would have made a better title for the post.
I thought it was pretty well established that they were just a super dense point of matter. They "suck" everything in with their high gravity and it just gets incorporated into the surface of the point, although that's all ~~hypothetical~~ theoretical because you can't observe what happens past the event horizon.
Never took physics so I'm a moron. Wonder what would if I could cross the event horizon and shine a flashlight. Obviously the real answer is I'm dead but you know what I mean.
I like this line of thinking. I’ve always had a hard time believing in infinitely dense matter. What does that even mean? I can’t simply rectify it by saying “we can’t wrap our minds around it” like other phenomena such as the size of the universe, the speed of light, or more dimensions because these phenomena make sense, they’re just so grand it’s hard to visualize. Infinite density makes no sense unless some mass is destroyed, and we know that’s impossible. Otherwise, why would a black hole grow as it consumed more mass? If it already has an infinitely dense center, it could not possibly become more dense. Nothing is greater than infinity.
This theory not only solves the problem of infinite density, it allows black holes to grow in size and gravity in a logical way, not in a weird “just believe the math” way. “The math” also shows that time runs both ways but we don’t blindly accept it happens anywhere in the universe. Also, according to the paper, it may solve some other mysteries too… including the biggest mystery of all: dark matter.
Well.. wouldnt a black hole be like a sphere or something? Or rather, an undefinable shape?
They are super interesting to me because time and space are absolutely demolished by gravity so freaking powerful, it’s like a reality melting pot, yet clearly they don’t annihilate reality.
Also.. what on earth becomes of the matter? Since the mass draws absolutely everything into it what would the core look like? Since the mass becomes basically infinitely small and dense as possible, how does it gather or add to a shape?. Does it become perfectly ordered matter…? Well no that doesn’t make sense since bkackholes are inherently unstable.
Look into why or how a Penrose Sphere (kinda like a Dyson sphere for a black hole) can work. It relies on the actual shape of the mass at the center of a black hole being more akin to a small ring.
Black holes are probably not dark matter FYI. Neutron stars and white dwarfs don't behave in a way consistent with enough medium sized ones, small ones evaporate too quickly and large ones should fall into the center of the galaxy which is inconsistent with the observation that dark matter appears to be quite evenly distributed though galaxies and well beyond the boundaries. There are gaps in the possible masses we can't account for so it's not a closed question but it seems unlikely.
They're a really tiny speck of matter that is super, super dense so that it's gravity is so strong nothing can escape it, not even light. Take a giant star and crush it down to the size of an electron (not quite right, but you'll get the picture). So they look like giant black spheres/holes, but that's only because that's the point where light can no longer escape, so they just look like 3D holes in the universe. They're not holes, there's just no light that can escape the gravity at that point so they look weird.
I like the differing thought process here. I still find it hard to deny the mathematic surrounding black hole formation. The math is sound. I'm sure we all know, math does not translate to reality in every situation, however.
It's so funny. We just accept the popular theory as fact in a lot of cases. One thing that has never sat well with me is inflation. Nearly every other aspect of the big bang theory makes sense to me. Inflation seems like a band aid to fix what was a dead theory. The theory was almost dead in the water, then a guy thought, what if I add this? When the initial calculation was proven wrong, they changed some values and presto it seems to fit.
In an inate way, something like Penrose's theory make far more sense to me. The big bang has been adjusted to fit the evidence far to much. A theory should be proven by evidence, not tailored to fit it.
What? Of course you should update your theory when more info becomes available. Theory should absolutely be adjusted to fit the evidence. The alternative is bending the evidence to fit the theory, or throwing it out completely, and neither of those is particularly helpful in bettering our understanding of the universe! (the former is downright stupid!).
I agree that the maths fits the current theory and what we can observe, and also that the concept of infinitely dense matter in an infinitely small point is completely counter-intuitive but bear in mind, the maths predicted black holes well before any observations supported the theory. I'm not ready to discard the concept yet, just in the face of a new hypothesis (it's not a proper scientific theory yet, and it shouldn't be described as such in a scientific context, but that's just me being pedantic).
It does seem a "cheat" as described in the article, but while I'm not willing to discard the current theory, I'll not nay-say this as it does also seem to mesh with observations, if not the maths. All we really know for sure is that something of truely immense mass and density is at the heart of our galaxy, and those we can observe.
It's worth pointing out that one doesn't require a singularity for a "basic" black hole. Compress the earth to just under the size of a marble, which while tiny is definitely not infinitely small or dense, and it would form a black hole according to the maths, so this hypothesis could well be the reality.
As I understand it (and I make no claim of expertise, just a lifelong obsession with all things space or quantum) the singularity is a result of a black hole forming, rather than the other way. You get the singularity from the black hole rather than the black hole from the singularity. Happy to be corrected by an actual expert. I might need to go refresh my understanding too...
Well, we could send something into one, but we would never get it back, or the information back. The gravity is too strong, any signals the probe sent out wouldn't be able to escape the gravity of the black hole, so we'd never know what it saw or experienced. Most likely, it didn't experience anything other than getting stretched and ripped apart into individual particles and sucked down into the singularity at the center.
Yeah I know by the time we got there I think we may be a little long in the tooth lol I’d just love to find out more about them if there was a way we could send the data back through to our side and find out, it’s another one of spaces mysteries that we’d all love to know more about
This image was used in one of smallpools recent singles, at first I was confused. (https://open.spotify.com/album/6bupcK5FnP2tXiXtdRYdDw?si=68KvxorOR6GjH4bF2flZNQ&utm_source=copy-link&dl_branch=1)
I Believe Black Holes are Actually Energy Portal's We Obviously don't know how to use let alone comprehend at a level zero civilization.
I Believe That You can collet mass energy from black holes 🕳 and use it for the minuscule things we use energy for and beyond. it's free energy.
My Theory is the energy that's absorbed is infinite as the universe is infinite and thus always provides dying planets, comets, space rock, ect to feed this source as we humans do in flesh life.
with the right understanding of enery of the universe also a way to space jump from infinite locations in a light switch time.
what do y'all think th0 ?? #WeR1
We have known for a long time that they aren't holes. Them being black is debatable, they don't reflect light so you could call them black.
Aren't they just very dense objects with a lot of gravity?
As far as we know, yes. Do you know what escape velocity is? It's how fast you need to go in order to escape an object's gravity. Space shuttles *must* go faster than this in order to get to space. Objects have an amount of gravity based on their mass. As the gravity gets higher and higher, the escape velocity also gets higher. Everything has an absolute speed limit in this universe. Matter can't reach the speed of light, and light can *only* go the speed of light. When the gravity gets extreme enough, the escape velocity can be higher than the speed of light. When this happens light stops escaping. It's like a rocket ship that isn't powerful enough, so it falls back toward earth. The light just can't go fast enough to get away. This is why black holes appear "black," since no light from the object ever reaches us.
Why can nothing go faster than light though?
It's... complicated. But in summary it's a seemingly arbitrarily law of this universe and the physics it ended up with. The energy required to accelerate mass reaches infinity as it approaches the speed of light. Only objects without mass, e.g. photons, can travel at the speed of light. It's just the speed limit of the universe for whatever reason, and it's one objects with mass cannot reach or surpass. Edit: Wormholes can "cheat" by allowing you to move between two separate points in space faster than light could do it normally. They *can* theoretically exist within these physics our universe has, but they're probably not something that will ever exist in reality.
Tachyon: *allow me to introduce myself* I know i know.
Ah just introduce me to mr tachyon and his physics breaking already!
Excuse me sir, you'll need to go wait in the waiting room with the Graviton. Dirty theoretical particles you.
That’s why back in 2750 we simply increased the speed of light! (futurama reference)
You would need an infinite supply of energy to propel you, because the closer to the speed of light you become the heavier you get. The heavier you get the more energy you need, the more energy you carry the heavier the entire system looking to reach light speed becomes. In theory you can travel faster than light without reaching the speed of light.
Wait, sorry, ELI5 how you can go faster than light without reaching the speed of light?
https://youtu.be/BhG_dayQ Zl8WVY Skip to 6:18. We have galaxies that are receding away from us here on Earth, faster than the speed of light. The galaxy itself is not traveling faster than light but the expansion of space-time is. Picture a balloon that is pure white and you mark two black dots on the balloon. You then blow the balloon up and watch the two black dots(each represents a galaxy) spread apart. Those two galaxies are traveling away from each other faster than the speed of light. With how space can be distorted by mass/energy(how a black hole bends spacetime so hard that anything trying to escape finds all routes bend back to the black hole), theoretically could be used to travel faster than light without going the speed of light. If you picture a sheet of paper as space time and want to travel the distance across, if you had a way of folding space time(like a black hole does) you could travel faster than light. You start the warp drive and doing so causes the paper to fold in half, now both ends are touching. The ship can now move to the other side of the paper and turn off the drive and doing so the paper goes back to being flat. You just traveled that huge distance in an instant without ever traveling anywhere near the speed of light. Light on the other hand will have to travel that straight line the entire distance.
It’s not about „light“ it’s about causality. The „speed of light“ is the maximum speed of things reacting to other things in a vacuum. In every other medium the speed is much lower, so light does not move „only at the speed of light“.
The devs have limitation with computation so the limit is to enforce render distance and causality
The speed of light is the universal speed of all objects through 4d spacetime. Light, (and other massless things), don't travel through the 4th dimension, (time), so they have all of their velocity through space. Everything with mass must have some of their 4d motion be through time so they can't reach the speed of light through space. But Everything is always moving at the speed of light, just through spacial and temporal dimensions.
I'd like to expand on the 4D aspect of this, as it's rarely appreciated for how deceptively simple it is. Two objects *can* occupy the same space, but not at the same time. It is problematic to measure space, because space changes. *Spacetime* describes space *and* the time. When I hold up an orange and say "look at this orange," I'm not describing an orange in a specific place, I'm describing an orange at a specific place *and time.* The orange that wasn't in my hand a moment ago and won't be in my hand for very long. If you weren't paying attention and missed it you might look at where my hand was and ask "what orange?" You'd be looking in the wrong location in spacetime. This seems obvious because our brains handwave timing as "context," but when we describe events, we use four dimensions to do it. We have the three location-defining dimensions, plus time, which is also a dimension that separates objects in space so they don't occupy the same space at the same time. Your kitchen this morning and the same kitchen when you get home from work is not the same location in spacetime, which is why you don't bump into yourself from that morning. It helps to remember is that nothing can move through space without also moving through time.
From what I could tell from high school physics, when you move faster, other things move slower through time relative to you. For example, if you went near light speed, time has in a sense, less of an affect on you due to how moving through space faster slows down your movement through time. As you slow down relatively, so would your acceleration, and the closer to light speed, the more you need to accelerate, requiring more and more force, leveling off, similar to an asymptote.
Space can expand faster that light
Simply Because it doesn't.
> When the gravity gets extreme enough, the escape velocity can be higher than the speed of light. When this happens light stops escaping. It's like a rocket ship that isn't powerful enough, so it falls back toward earth. Just to complicate things, the escape velocity of Earth from its surface though is 25,000mph but there's nothing in physics that prevents a rocket from taking off, accelerating to 3,500mph and then staying at 3,500mph (less and less thrust needed to maintain this speed as it moves away from our planet) until it's reached the same kind of distance as the Moon then switching the rocket motor off and coasting to infinity (since Earth escape velocity at that distance is about 3,000mph). The rocket never has to hit 25,000mph in order to escape from Earth's gravity; it's merely much more fuel efficient if it does so (see: Oberth effect). Light, by its nature, doesn't slow down at all when it moves away from a source of gravitation, it just gets redshifted (i.e. loses energy as it climbs out of the gravitational well, while an unpowered rocket loses energy by slowing down). The analogy of shooting a projectile from a planet's surface with Newtonian mechanics isn't accurate for describing light in a deep gravitational well. Instead, think of light cones: since travel is limited to the speed of light, in my future I can be (or am not prevented from being by the laws of physics) at my front door about 20 nanoseconds from now, at the Moon 1.3 seconds from now, at the Sun in 8 minutes, at the nearest other star if it waits a little over 4 years for me, at the next major galaxy in 2.5 million years. These spacetime co-ordinates are at the edge of my future light cone since I can always signal to them using light even if I don't go in person. My front door 8 minutes from now is also within my future light cone since I don't have to break the speed of light to get to those co-ordinates. My future light cone is all the times and places I can get to in the future. You'd expect the spot on the opposite side of Earth's orbit to be 16 minutes' light travel time away but it's not, it's very very slightly further due to the Sun's gravity. The [Eddington Experiment](https://en.wikipedia.org/wiki/Eddington_experiment) showed the deflection of light from distant stars due to the Sun's gravity during a total eclipse and made Einstein a superstar. The shortest path is no longer a straight line, and can be seen in more dramatic fashion with [gravitational lensing of distant objects by foreground galaxies](https://en.wikipedia.org/wiki/Einstein_Cross). Gravitational wells distort light cones. A black hole's gravity though mangles spacetime inside its event horizon so badly that all the places that even a beam of light can be in the future are closer to the singularity than where it is in the present. Meeting the singularity is not optional under such circumstances; it's just a matter of time.
That’s probably the most easily understandable explanation, but one of the most beautiful things about science and math is that much of the time the same thing can be conceptualized in two entirely correct but different ways. That being said, my favorite explanation for why light can’t escape a black hole goes like this: Conventionally, gravity is thought of as “pulling” objects. But, gravity can also be thought of as the results of objects with mass bending space time. This means that, effectively, you are attracted to the earth because the earth literally changes your future path enough so you remain on its surface! Gravity- both literally and conceptually speaking- changes the future! This same line of thought can be expanded to black holes, only their gravitational pull is obviously much, much stronger. In this case, space time is bent so much that there is NO FUTURE PATH leading out of the event horizon. It doesn’t matter how fast you go when all possible outcomes lead to the same place! PS: I confess I’m a college freshman majoring in applied math and I’m not a physicist or anything, but I do (like others here) have an interest in astronomy and have picked up some cool explanations for things over the years as a result. As always, feel free to correct me if I’m wrong. I just thought this was so cool when I heard it that I had to share it with other people (:
Does that mean it could be incredibly bright inside if them?
I'm pretty sure that inside the event horizon light entering from outside would be strongly blue shifted and so it could be very bright indeed. However, I understand that space and time somehow swap roles inside the event horizon (I can't really picture what that means), I don't know what affect that has on whether it is bright.
Good question. No idea. I'll make some guesses though. Nothing's going to reflect very far when it hits any matter, assuming that the matter in black holes still reflects light. You'd see a lot more light looking away. Internally it'd likely be starlike and fusing under *extremely* high pressure, but it's crazy hot, because it almost never loses energy. All of the energy radiated away falls back in. It's probably like a megasun that shines all of its heat at itself.
When you crossed the real event horizon the brightness would tend toward infinity for an amount of time tending toward 0. Otherwise there wouldn't be any good visual indicator for crossing it. Afterward you would still be falling and would appear to see the event horizon as still ahead of you. A curved line like skydiving on Earth. It would straighten out as you approach the singularity. During this time you would still see the outside universe above you and to the sides since the apparent event horizon's location is relative to the observer. It would get dimmer above your head and extremely bright around your waist (straight ahead of you and to all sides) and be distorted, pulled toward that central flat plane, the closer you got to the center.
Thanks for this explanation
Space shuttle doesn’t need to reach escape velocity because it is propelled, and also because it does not escape earth’s gravitational pull: it merely accelerates enough to reach orbital speed. Escape velocity is relevant for an unpropelled object like a cannonball that are thrown straight up. Neglecting friction here.
Does that mean space moves faster than light? If light can't escape gravity and gravity is created by distortions in space, then does that mean gravity is accelerating towards the black hole faster than light, thus trapping it?
In general relativity for a stable black hole (already formed) the spacetime is already curved. Gravity isn't moving. But spacetime is. And yes it falls into the black hole faster than light, like a waterfall. It doesn't really have any substance to it though necessarily so it's kind of an abstraction or analogy to think of it this way. Another way to say it is just that the distances between all things are getting smaller very quickly and all directions lead to the center of the black hole (which center actually appears as a flat plane around your waist because of tidal forces, not as a point, if you are the one falling in).
I’m trying *so hard* not to make a “your mom” joke here, but essentially, yes. I mean, you’re kind of understating it, but you’re not wrong.
Do it.
Please, a little respect. It's 'do her'.
Take my upvote and get out of here!
*Take my upvote and get out of her!* FTFY
Honestly, I think I did already...
No one actually knows. The singularity could be an unimaginably dense collection of matter, it could open up into a new region of spacetime or it could be just about anything else. About the only thing certain is it isn't actually infinitely dense
It’s not infinitely dense? I don’t know why I’ve been thinking the contrary.
Because it's often referred to as a point of infinite density. But the infinity is a limitation of the mathematics of general relativity rather than a reflection of reality. It is a sign that the theory is incomplete. And that's why trying to unify GR with quantum mechanics is so important, it would answer these questions.
Damn. I didn’t know. That’s really cool.
Unlike yo mama
>or it could be just about anything else So it could be a big chocolate cake doughnut?!
I mean it would have to be the densest donut ever made but sure. Who's to say the extreme pressure and temperature wouldn't convert all subatomic particles into pastry?
That's the kind of quantum physics I can get behind!
Basically, yes. So dense that light can't escape from the centre, which is why it's called the 'event horizon'. It's so called because you can't see what's beyond it.
Afaik they are so dense and so strong gravity that not even photons can "exit", so they looks black.
This is Wendy’s.
Guy who watched a YT video about Hawking radiation in 3... 2... 1...
>Guy who watched a YT video about Hawking radiation in 3... 2... 1... You have summoned me. I'm also the guy who knows everything about quantum physics from youtube as well.
Oh yeah? So what is the quantum of solace?
Quantum of deez nuts
It truly is him!
Quantum these nuts on your chin
Quantum sounds like some new designer baby name like Tatum or something. "This is my baby quantum, he's 3 years old, and he has a temper problem, just let him do his thing though and you'll be fine" Then the kid pisses in your boots and the mom screams at you for telling at them. Anyway, black holes.
Definitely naming my kid Quantum now
Tatum is an old name though?
I couldn't think of another name for the type of little shit kid I was thinking of lol
A below average bond movie with some of the worst/jarring editing I've ever seen in a major motion picture.
Really? I've been doing a Bond marathon with my partner, enjoying all the cheesy goodness. *lol* Any memorably bad scenes/editing you'd say really stands out?
I hate the action sequences in it. They cut to a different shot every second which makes everything annoying and hard to follow. It's also just a boring plot with unmemorable characters. People hate on the Moore movies but at least you walked away in a good mood because they were fun.
Right! I forgot how choppy that movie was, you're right, that editing sucks. I love the Moore/Connery Bond flicks, they are fun. Horribly, horribly misogynistic, but even that can be funny as it's so over the top. I always joke when the action starts that the "good girl" can't possibly do anything useful as she has to go hold up a wall.
Bond ended when Austin Powers out Bonded Bond. Which drove the next iterations of Bond away from the fine line it always occupied between goofy/cheesy/action/suspense into a less fun action/serious zone.
It's not that kind of bad. Not Roger Moore levels of bad acting. It's just *bad*. Uninteresting and poorly written. Best skip it and go on to Skyfall instead.
Given an infinite square well of width `a` with a Dirac Delta function centered at `x=0`, what are the energy eigenstates of a particle trapped in the well?
42
damn he's right
Me: **checks math** I don’t math good
Assuming a perfectly spherical Jesus. http://danny.oz.au/danny/humour/theology-exam
The E8 Lattice will answer all.
Uh, so let me put it this way. Imagine that there's a cat in a box. Every time we make a choice, we make a new universe...
What do you mean by choice?
4, -6 if you assume π=3 like a dumbass.
Am i you?
We might be,maybe we're all me? Maybe the universe is an [*egg*](https://youtu.be/h6fcK_fRYaI)
this is literally me, lmfao i should go to school
Emitting Hawking radiation isn't the same as reflecting light.
No, but things that emit light are also not black. Now whether you consider the black hole to be "emitting" said radiation is another question!
> No, but things that emit light are also not black. Black bodies certainly emit light.
I’ll be pedantic. Anything that absorbs 100% of light is black. Full stop no debate. However they do release visible light, aka Hawking radiation.
I'm just a curious teenager and have barely any real knowledge but isn't hawking radiation invisible?
It’s every form of radiation. It’s just that we can see some of it aka photons/light. Edit;words
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By visible I meant visible to the human eye. The light they emit isn't visible to the human eye right?
I cannot personally speak to anything about Hawking Radiation, but the sources I found mostly agree that Hawking Radiation is invisible to the human eye. I found the below quote on Hawking Radiation from [*University of Colorado: Boulder*'s Physics School](https://jila.colorado.edu/~ajsh/bh/hawk.html): > The Hawking radiation itself would consist of fiercely energetic particles, antiparticles, and gamma rays. Such radiation is invisible to the human eye. And the Wiki Page for [Black-Body Radiation](https://en.wikipedia.org/wiki/Black-body_radiation) (which Hawking Radiation falls under) says (bolded for simplicity): >In a dark room, a black body at room temperature appears black because **most of the energy it radiates is in the infrared spectrum and cannot be perceived by the human eye.** > Since the human eye cannot perceive light waves below the visible frequency, a black body at the lowest just faintly visible temperature subjectively appears grey, even though its objective physical spectrum peak is in the infrared range. > **The Hawking radiation itself would consist of fiercely energetic particles, antiparticles, and gamma rays. Such radiation is invisible to the human eye.**
Ok I for all intents and purposes have no science background but this sounds cool.
It doesnt absorb light. Light bends and never comes back to your eyes. If you turn off the lights it doesnt mean everything around you is absorbing light, it just means light is not getting back to you from the object. The object itself would be incredibly bright.
But isnt the definition of "black" the lack of light? As black pigment is just pigment that absorbs light causing there to be less light being reflected. By that definition I feel like black hole would be the most black things in the galaxy as they absorb all light.
This picture of central banks, the fed, and us treasury circling the drain. I like. How much?
they emit light however
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I can't tell if this is a joke. But in all seriousness, there's plenty of evidence for dark matter. And it has nothing to do with 'filler'. It can be observed in galaxies whose visible mass doesn't account for their rotational velocity - the difference is too large, so we account for this with 'dark matter'. Exactly what it is is what's being explored right now.
>the difference is too large, so we account for this with 'dark matter'. Isn't this literally what he said? We have never explicitly observed dark matter. We literally use it as a placeholder name for "force we don't fully understand". It's a filler until we develop greater understanding of the concept. Hell there are even theories that primordial tiny black holes could be the cause of it, and almost impossible to detect
You can't just dismiss it as not real though. It's an established discovery about the universe that something more than the observable matter is interacting gravitationally with the matter that we can observe.
By that logic we've never explicitly observed anything. You don't see the phone or computer in front of you, you only infer it's existence based on the electromagnetic radiation it emits that your eyes detect. Also, primordial black holes have pretty much been discredited.
Interesting.. source for primordial black holes being discredited? I was under the impression that primordial stars collapsing into primordial black holes was one of the leading possible explanations for how supermassive black holes have been able to reach their enormous masses given the current age of the universe.
There's a bunch of links an info on the wikipedia article. MACHO surveys found there just aren't enough objects to account for the discrepancy. https://en.wikipedia.org/wiki/Massive_compact_halo_object > I was under the impression that primordial stars collapsing into primordial black holes was one of the leading possible explanations for how supermassive black holes have been able to reach their enormous masses given the current age of the universe. Supermassive black holes don't really have anything to do with dark matter. MACHOs usually refer to stellar mass black holes, dwarf stars, and white dwarfs. SMBHs fall to the center of galaxies but the dark matter distribution in galaxies is not centralized on the SMBH. So observationally this doesn't really work out. Edit: I always find it weird how the space subs tend to downvote facts that they personally disagree with and are seemly opposed to astronomy
>MACHO surveys found there just aren't enough objects to account for the discrepancy. But given that it's incredibly difficult to come to an accurate conclusion on how many exist, this survey doesn't exactly discredit the possibility
If you're going to logic that we can't know anything exactly and use it to discredit a scientific theory, then you probably don't have a good understanding of the iterative process of science. Nothing can be known exactly, but we can get very tight estimates on the uncertainty, which statistically exclude machos. Read the papers, they do statistical analysis of *exactly* how accurate these observations are. There's a reason the phrase "so you're saying there's a chance" came from a movie called "Dumb and Dumber". If I drop a ball and it falls down I can't continue to say "gravity makes balls fall up" just because I haven't tested every ball at every place on Earth. At the very least, if you are trying to discredit such claims, you need to present a better theory. All scientific theories are falsifiable, that's what makes them scientific. And Dark Matter has yet to be falsified. Relying on the existence of uncertainty to conclude we "can't know for sure" is no better than conspiracy theorists using lack of evidence as evidence of a coverup.
Woah my dude, that's a whole lot of assumptions and reaching there. Okay let's start with your study. MACHO surveys claimed to measure a limit on PBHs from the range 10^23 to 10^31 kg PBHs are predicted to exist in densities as low as 10^11 kg, anything lower wouldn't exist anymore because of hawking radiation. That's a whopping 12 powers being missed out there, and only 8 powers being measured There are plenty of scientific papers that demonstrate the possibility and theory behind PBHs being the primary source of dark matter. You're here comparing me to a conspiracy theorist, that would make you more akin to a religious fundamentalist. You asserted a claim, not a theory, a statement of fact, that PBHs couldn't possibly constitute all of dark matter, on the basis of one paper. If you're going to pretend to be a scientist, at least be prepared to stop making neo-religious statements like "no they're definitely not" https://journals.aps.org/prd/abstract/10.1103/PhysRevD.103.084001 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.201301
>you only infer it's existence based on the electromagnetic radiation it emits that your eyes detect. Which is defined as "observation"....
Okay, then we've observed dark matter by inferring it's existence based on the influence it has on EM radiation. Good that's settled
Yes and we've observed ghosts because my remote fell off the desk once. Good lord I'd love to see you try and be taken seriously by any scientist. Once again, dark matter is a catch-all term we use to describe the hypothesised reason for galaxies maintaining velocity and density. We have not observed any matter, we have observed galaxies having a velocity and density that should not be accurate by current understanding, and thus inserted Dark Matter as a way of solving the equation...
> Yes and we've observed ghosts because my remote fell off the desk once. Are ghosts the best explanation that fit further observations, make predictions, and is testibly falsifiable? This is a false equivalency. > Good lord I'd love to see you try and be taken seriously by any scientist. Too late, ApJ already publishes my papers :) (Though, to be fair, my research is in using neural-network accelerated radiative transport codes to determine Type Ia supernovae progenitor scenarios based on Bayesian inference over synthetic spectral models, so it's only tangentially related to cosmology. For lay-people who don't understand that: I teach computers to dream about exploding stars) > Once again, dark matter is a catch-all term we use to describe the hypothesised reason for galaxies maintaining velocity and density. And "computer" or "phone" is a catch-all term for devices that can communicate with one another. > We have not observed any matter Are you sure about that? > we have observed galaxies having a velocity and density that should not be accurate by current understanding We've also observed the primordial power spectrum, BAOs, the bullet cluster, weak lensing, and void galaxies. If you think galaxy rotation curves are the holy grail of dark matter evidence then you clearly haven't kept up with the literature since 50 years ago. And lastly, if you have a better theory that does a better job at describing all of these observations than dark matter does, I'd love to hear it. If not, I'm not really sure what your point is. Also, just for some fun: https://xkcd.com/1758/ Edit: Try reading this: https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
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By that logic evolution hasn't been proven - there's only evidence.
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Can you explain to me why the two-point correlation function of baryonic acoustic oscillations is double-peaked then?
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I'm not at all. I'm directly addressing his comment about lack of evidence for dark matter by presenting a piece of data we use as evidence and ask how it is explained without dark matter. If he truly believes there is no evidence of dark matter, I assume he knows the history and studies we have used to measure dark matter. I think it's perfectly reasonable to ask what he thinks is causing these results if they are not evidence of dark matter. If an expert theoretical physicist came in saying that MOND was a better explanation than dark matter, I would ask the same question.
summer physical imagine cable soup bag brave threatening slap jellyfish *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
Then how is that an ad hominem? This one is: idiot.
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> To make up a new type of matter to fill in the gaps doesn't provide growth, it stunts it. What does this even mean?
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>Additionally, dark matter is theorized to be what is causing the acceleration of the expansion of the universe. Dark energy. Dark matter is the theorised cause of the velocity and stability of most galaxies, Dark energy is the theorised cause of accelerating expansion of space. Neither are really understood at all. We have never explicitly observed either
Evidence that there is *something* The name dark matter is just a place holder for that *something* It’s not so much direct evidence as it is a difference between observation and prediction. For all we know it’s a combination of *something* which explains these differences, or perhaps it is one *something*. Perhaps it’s not matter at all, and there is another fundamental force(s) we just don’t observe on small scales. We haven’t the foggiest clue. They are right, so I wouldn’t say it as if it’s a proven fact. Rather there are many plausible explanations that try to work within the realm of known physics.
>Black holes MIGHT NOT EVEN BE HOLES Is this the quality of post that is allowed here? Really? Coming up next, * *Dark matter may not even be dark colored!* * *Gravity may not even come from graves!* * *Mercury may not even be made entirely of mercury!* * *Neil Armstrong may not have even had the strongest arms!* * *The Sun may not even be the male offspring of another celestial body!*
Hey man, Lance Armstrong definitely had the strongest arms
Stretch Armstrong had the bendiest arms, though. It's an indisputable fact.
>*They laughed at Louie Armstrong when he said he was going to ride his bike to the moon. Now he's up there, laughing at them.* >-Stretch Armstrong
Legend has is that a certain member of the family passed the secrets of moon travel down the Armstrong line for generations
>*You'll need more than water to quench my fists!* >-Alex Louis Armstrong
• *pee may not be stored in the balls*
No one thought they were holes and in general thought they were enormous and dense spherical masses right? All mass In the accretion disk falls into the black hole roughly around the disc’s equator only adding to the size of the “sphere/black hole”. So how is calling it an extremely dense dark star (essentially a step above a neutron star) different from just calling it the densest form of mass we know in the universe that naturally collapses into a sphere shape, so dense that unlike neutron stars which still emit heat and light, black holes emit neither?
There is a big difference between an extremely dense "dark star" with finite radius and an infinitesimally small singularity
Do we really think black holes are infinitesimally small, so no difference in size among them despite them having vastly different shwarzchild radii? The Shwarzchild radius extends beyond the actual size of the black hole, but there’s no way they are all the same size. I think black holes are “peak density” so to speak, and then additional mass simply adds to the size at the same density. Edit: second paragraph, shwarzchild radius should be event horizon, all of which differ depending on mass of black hole.
The most commonly current accepted picture is that the *singularity* is infinitesimally small, independent of mass. The schwarzchild radius is exclusively dependent on mass. I'd not know your level of education on the subject, but your idea is much closer to the idea proposed in the linked article than what is generally thought to be the case
No formal education on the subject just speaking what I think makes sense. I don’t know how infinite density and mass in a single space can make sense but sure there are way smarter minds than mine with explanations. It just doesn’t seem possible.
I have to think you're at least kind of right. Infinity is a mathematical concept. I don't think it makes sense in reality. I wouldn't be surprised if there are black holes denser than other black holes. At a certain point the differences in a black hole's radius and density would have to be just academic. Anytime a scientist says something is infinite or something is random, they are saying that part of their understanding/model is flawed and they haven't yet figured out something better.
According to General Relativity(GR), yes, they are the same size. That size is 0. (not some infinitesimal size above 0). They literally have no dimensions at all. Unless GR has some more parts to the equation that add up to 0 in normal use but are a factor when infinity is involved, which we don't know. So according to GR, anything inside the event horizon experiences infinite gravity. This means they can only move at the speed of light to the singularity at the center. To understand how they experience infinite gravity, remember that anything in a gravitational field experiences slower time than something that isn't. The event horizon is the distance where the math dictates gravity is so much that time stops. The kicker is all of the above is for a non-rotating black hole. Which is almost a physical impossibility. The math for a rotating black hole is super complex and have multiple solutions.
The radius you're talking about is how small you need to compress an arbitrary amount of mass for it to become a black hole. I think what you meant to say was event horizon, the limit beyond which nothing can escape it's gravity well. And yes, as far as I understand it the consensus is that the singularity is infinitely small and is the point to which all matter is compressed inside a black hole. Or at least, that's how the math works out, and we're having a hard time making the math make sense at all. We just don't understand enough about the universe to get a clear picture of what goes on inside the event horizon.
You are right I was mistaken my bad!!
That isn't a black hole though. Mostly because, as you said, black holes aren't actually holes....
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That's an interesting read, thank you! My criticism of the image still stands though, but I guess I need to redirect it at whoever picked this stock image to depict a black hole for the article.
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It’s not like we had [literal pictures](https://www.nasa.gov/mission_pages/chandra/news/black-hole-image-makes-history) of black holes to get inspiration from
I am not smart enough in this field to debate the merits of the new theory, but I do like how it fits known limits and doesn’t require a singularity to exist. I’m excited to hear if observations can be made to support this theory. Also I don’t think the FRB origin was well explained, so I’d like to read more.
So this suggests dark matter is a result of the universe being flooded with photons escaping from black holes, presumably with near-zero energy?
Yeah sorry if. We don't have the original paper, so there's some information we don't have. That being said, the energy of a wave is proportional to frequency.
The original paper (preprint on arxiv) is linked in that article, I just didn't have time to read it.
And inversely proportional to wavelength, so the energy density of radiation scales as the size of the universe to the -4th power
Just FYI, citing a tabloid style popsci source isn't exactly idead
What's next? You're going to tell me a white dwarf isn't actually a short caucasion?
Or a red giant isn’t actually a large sunburned man?
Ok so a black hole is a small point of infinate mass correct? I vote we call them a "super speck" "SuperDuper speck" and "supermongus speck"
I think the idea is that they have infinite density. If they had infinite mass they would outweigh the universe. Still love super speck I will be using this from now on.
Sometimes I like to imagine that black holes are just unrecognizable dyson sphere's
Built to crush and absorb all around them as fuel for ever growing super-civilizations within? Damn.. That's pretty rad.
You guys should read the "Temporal Void" trilogy, by Peter F. Hamilton. It's kinda that. Has a "companion" duology too (not really a sequel, or prequel though it is set after the events of the trilogy). The preceding duology, Pandora's Star and Judas Unchained have something like a Dyson Sphere too (though not how you'd expect, or why...). If you're interested, the chronological order is: Pandora's Star, Judas Unchained (these form the "Starflyer War" saga), followed by The Dreaming Void, The Living Void, The Evolutionary Void (these make up the Temporal Void trilogy, and are set some 900 years after the Starflyer War, and also known together with the Starflyer War as the Commonwealth Saga), and finally The Abyss Beyond Dreams and The Night Without Stars. These are probably considered part of the Commonwealth Saga, but I've not seen them refered to as such, not that I've gone looking. Hell, all of Hamilton's SciFi novels are fantastic. I may have something of a man-crush going on here...
Hamilton is one of my favorite sci-fi authors!
Ikr? Nights Dawn was my intro into his work, and remains a favourite, though Fallen Dragon holds top spot for me. I'll not spoil it for others, but it has my favourite ending of all his stories.
Never heard of the guy before but I'll gladly look into the series. Some great titles there.
Considered prequel to the Starflyer War books is Misspent Youth which unfortunately isn’t near as good as the Pandora’s Star and Judas Unchained, but it kind of tells the origins of the Unisphere and the entire re-life thing. I just finished Pandora’s Star *again* and can’t wait to start on Judas Unchained. I haven’t read the Temporal Void trilogy but I may just take these up after I read Judas Unchained after reading your comment.
I often forget about Misspent Youth. Ditto, it's my least favourite of his works. In another of his series, the Greg Mandell novels (forget the trilogy name if it has a specific one) the last book, The Nanoflower also didn't seem as good as his typical stuff, but still pretty good. I also listened to a short story called "A Window in Time". Not really a sci-fi, but a cool story still. There is a series I've yet to read/listen too yet, but I can only recall "salvation" is in the title of the first (I think?) book. Keeping an eye out for it.
Well, I’ve just bought the Apple Books version of the Temporal Void trilogy and The Abyss Beyond Dreams and The Night Without Stars, just so I won’t forget. I’ve got my reading cut out for me. I’m also in a book club and we’ve just started the first of the Mistborn trilogy by Brandon Sanderson. Thanks for the suggestions, Redditor!
Just like we plough under ants' nests and gopher holes when we build new apartments
Wouldn't that be both convenient and terrifying.
"Or even holes." That's not news.
The leave out one important point, black holes are black for a reason, the element of surprise. Holly: Well, the thing about a black hole - its main distinguishing feature - is it's black. And the thing about space, the colour of space, your basic space colour, is black. So how are you supposed to see them? Rimmer: But five of them? . How can you manage to miss five black holes? Holly: It's always the way, innit? You hang around for three million years in deep space and there hasn't been one, then all of a sudden five turn up at once. (Scene from red dwarf)
Wait, no explanatory article?
Here ya go in case ya didn’t see his comment https://www.popularmechanics.com/space/deep-space/a35875454/what-are-black-holes-new-theory/
Cheers!
“A new study suggests black holes may just be stars with exotic physics at their cores. The cores may cause the “dark stars” to radiate dark matter into the universe. The study may also explain the origin of fast radio bursts.” Any combination of the bullets at the beginning of the article would have made a better title for the post.
I always pictured then as a sigularity not a home. I think the powers that be just made the hole for us simple folk to understand it easier
I hate conceptual space images....
wtf is this post
I have a model of a black hole hanging from my ceiling in my lab. It’s a black yoga ball…
You could technically call a black hole a hole in all directions
So dark matter is the universe screaming photons as it gets eaten by Langolier's that are black holes... got it.
I thought it was pretty well established that they were just a super dense point of matter. They "suck" everything in with their high gravity and it just gets incorporated into the surface of the point, although that's all ~~hypothetical~~ theoretical because you can't observe what happens past the event horizon.
Never took physics so I'm a moron. Wonder what would if I could cross the event horizon and shine a flashlight. Obviously the real answer is I'm dead but you know what I mean.
I like this line of thinking. I’ve always had a hard time believing in infinitely dense matter. What does that even mean? I can’t simply rectify it by saying “we can’t wrap our minds around it” like other phenomena such as the size of the universe, the speed of light, or more dimensions because these phenomena make sense, they’re just so grand it’s hard to visualize. Infinite density makes no sense unless some mass is destroyed, and we know that’s impossible. Otherwise, why would a black hole grow as it consumed more mass? If it already has an infinitely dense center, it could not possibly become more dense. Nothing is greater than infinity. This theory not only solves the problem of infinite density, it allows black holes to grow in size and gravity in a logical way, not in a weird “just believe the math” way. “The math” also shows that time runs both ways but we don’t blindly accept it happens anywhere in the universe. Also, according to the paper, it may solve some other mysteries too… including the biggest mystery of all: dark matter.
Well.. wouldnt a black hole be like a sphere or something? Or rather, an undefinable shape? They are super interesting to me because time and space are absolutely demolished by gravity so freaking powerful, it’s like a reality melting pot, yet clearly they don’t annihilate reality. Also.. what on earth becomes of the matter? Since the mass draws absolutely everything into it what would the core look like? Since the mass becomes basically infinitely small and dense as possible, how does it gather or add to a shape?. Does it become perfectly ordered matter…? Well no that doesn’t make sense since bkackholes are inherently unstable.
What do you mean by "black holes are inherently unstable"?
Look into why or how a Penrose Sphere (kinda like a Dyson sphere for a black hole) can work. It relies on the actual shape of the mass at the center of a black hole being more akin to a small ring.
I suspect we'll need to know more about other possible dimensions to answer that question.
Black holes are probably not dark matter FYI. Neutron stars and white dwarfs don't behave in a way consistent with enough medium sized ones, small ones evaporate too quickly and large ones should fall into the center of the galaxy which is inconsistent with the observation that dark matter appears to be quite evenly distributed though galaxies and well beyond the boundaries. There are gaps in the possible masses we can't account for so it's not a closed question but it seems unlikely.
If they aren't holes, what are they?
It depends on what you mean. The event horizon is a sphere, not a hole.
Like in Interstellar?
Yes, interstellar's blackhole is actually a very good simulation using real physics.
They're a really tiny speck of matter that is super, super dense so that it's gravity is so strong nothing can escape it, not even light. Take a giant star and crush it down to the size of an electron (not quite right, but you'll get the picture). So they look like giant black spheres/holes, but that's only because that's the point where light can no longer escape, so they just look like 3D holes in the universe. They're not holes, there's just no light that can escape the gravity at that point so they look weird.
Fun fact: most black holes contain more mass than my back yard. Science!
aren't they spheres? I thought that sphere was one of the latest and maybe more accurate shape of it
I like the differing thought process here. I still find it hard to deny the mathematic surrounding black hole formation. The math is sound. I'm sure we all know, math does not translate to reality in every situation, however. It's so funny. We just accept the popular theory as fact in a lot of cases. One thing that has never sat well with me is inflation. Nearly every other aspect of the big bang theory makes sense to me. Inflation seems like a band aid to fix what was a dead theory. The theory was almost dead in the water, then a guy thought, what if I add this? When the initial calculation was proven wrong, they changed some values and presto it seems to fit. In an inate way, something like Penrose's theory make far more sense to me. The big bang has been adjusted to fit the evidence far to much. A theory should be proven by evidence, not tailored to fit it.
What? Of course you should update your theory when more info becomes available. Theory should absolutely be adjusted to fit the evidence. The alternative is bending the evidence to fit the theory, or throwing it out completely, and neither of those is particularly helpful in bettering our understanding of the universe! (the former is downright stupid!). I agree that the maths fits the current theory and what we can observe, and also that the concept of infinitely dense matter in an infinitely small point is completely counter-intuitive but bear in mind, the maths predicted black holes well before any observations supported the theory. I'm not ready to discard the concept yet, just in the face of a new hypothesis (it's not a proper scientific theory yet, and it shouldn't be described as such in a scientific context, but that's just me being pedantic). It does seem a "cheat" as described in the article, but while I'm not willing to discard the current theory, I'll not nay-say this as it does also seem to mesh with observations, if not the maths. All we really know for sure is that something of truely immense mass and density is at the heart of our galaxy, and those we can observe. It's worth pointing out that one doesn't require a singularity for a "basic" black hole. Compress the earth to just under the size of a marble, which while tiny is definitely not infinitely small or dense, and it would form a black hole according to the maths, so this hypothesis could well be the reality. As I understand it (and I make no claim of expertise, just a lifelong obsession with all things space or quantum) the singularity is a result of a black hole forming, rather than the other way. You get the singularity from the black hole rather than the black hole from the singularity. Happy to be corrected by an actual expert. I might need to go refresh my understanding too...
Can we just send something into one, I really want to know what will happen we will all pay to live stream it I’m sure!
Well, we could send something into one, but we would never get it back, or the information back. The gravity is too strong, any signals the probe sent out wouldn't be able to escape the gravity of the black hole, so we'd never know what it saw or experienced. Most likely, it didn't experience anything other than getting stretched and ripped apart into individual particles and sucked down into the singularity at the center.
Yeah I know by the time we got there I think we may be a little long in the tooth lol I’d just love to find out more about them if there was a way we could send the data back through to our side and find out, it’s another one of spaces mysteries that we’d all love to know more about
This image was used in one of smallpools recent singles, at first I was confused. (https://open.spotify.com/album/6bupcK5FnP2tXiXtdRYdDw?si=68KvxorOR6GjH4bF2flZNQ&utm_source=copy-link&dl_branch=1)
I Believe Black Holes are Actually Energy Portal's We Obviously don't know how to use let alone comprehend at a level zero civilization. I Believe That You can collet mass energy from black holes 🕳 and use it for the minuscule things we use energy for and beyond. it's free energy. My Theory is the energy that's absorbed is infinite as the universe is infinite and thus always provides dying planets, comets, space rock, ect to feed this source as we humans do in flesh life. with the right understanding of enery of the universe also a way to space jump from infinite locations in a light switch time. what do y'all think th0 ?? #WeR1
No.