Does Dark Matter Come From Black Holes Formed Before the Big Bang? (livescience.com) 104
"The Big Bang may not have been the beginning of the universe," writes LiveScience, citing "a theory of cosmology that suggests the universe can 'bounce' between phases of contraction and expansion."
The recent study suggests that dark matter could be composed of black holes formed before the Big Bang, during a transition from the universe's last contraction to the current expansion phase... In the new study, researchers explored a scenario where dark matter consists of primordial black holes formed from density fluctuations that occurred during the universe's last contraction phase, not long before the period of expansion that we observe now. They published their findings in June in the Journal of Cosmology and Astroparticle Physics ... In this "bouncing" cosmology, the universe contracted to a size about 50 orders of magnitude smaller than it is today. After the rebound, photons and other particles were born, marking the Big Bang. Near the rebound, the matter density was so high that small black holes formed from quantum fluctuations in the matter's density, making them viable candidates for dark matter.
"Small primordial black holes can be produced during the very early stages of the universe, and if they are not too small, their decay due to Hawking radiation [a hypothetical phenomenon of black holes emitting particles due to quantum effects] will not be efficient enough to get rid of them, so they would still be around now," Patrick Peter, director of research at the French National Centre for Scientific Research (CNRS), who was not involved in the study, told Live Science in an email. "Weighing more or less the mass of an asteroid, they could contribute to dark matter, or even solve this issue altogether."
The scientists' calculations show that this universe mode's properties, such as the curvature of space and the microwave background, match current observations, supporting their hypothesis.
"If this hypothesis holds, the gravitational waves generated during the black hole formation process might be detectable by future gravitational wave observatories, providing a way to confirm this dark matter generation scenario..."
The recent study suggests that dark matter could be composed of black holes formed before the Big Bang, during a transition from the universe's last contraction to the current expansion phase... In the new study, researchers explored a scenario where dark matter consists of primordial black holes formed from density fluctuations that occurred during the universe's last contraction phase, not long before the period of expansion that we observe now. They published their findings in June in the Journal of Cosmology and Astroparticle Physics ... In this "bouncing" cosmology, the universe contracted to a size about 50 orders of magnitude smaller than it is today. After the rebound, photons and other particles were born, marking the Big Bang. Near the rebound, the matter density was so high that small black holes formed from quantum fluctuations in the matter's density, making them viable candidates for dark matter.
"Small primordial black holes can be produced during the very early stages of the universe, and if they are not too small, their decay due to Hawking radiation [a hypothetical phenomenon of black holes emitting particles due to quantum effects] will not be efficient enough to get rid of them, so they would still be around now," Patrick Peter, director of research at the French National Centre for Scientific Research (CNRS), who was not involved in the study, told Live Science in an email. "Weighing more or less the mass of an asteroid, they could contribute to dark matter, or even solve this issue altogether."
The scientists' calculations show that this universe mode's properties, such as the curvature of space and the microwave background, match current observations, supporting their hypothesis.
"If this hypothesis holds, the gravitational waves generated during the black hole formation process might be detectable by future gravitational wave observatories, providing a way to confirm this dark matter generation scenario..."
With enough dimensions you can fit anything (Score:2)
AFAICS while the standard model has made some predictions, cosmology can't really lay claim to that. Cosmology seems to me a craft of fitting. Big bang was to fit red shift, inflaton/inflation was to fit CMB, dark matter was to fit galaxy rotation, dark energy was to fit accelerating expansion.
If you are going to fit something, just fit an oscillating universe ... it's more aesthetically pleasing.
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PS. I suggest Darker Energy to make the universe contract again against the force of Dark Energy.
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Or you just break it and the whole thing shuts down
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I think that's called "collapse of the false vacuum".
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Neil Degrassi High'son thinks we're 50-50 living in a simulation....
(1) create paradox
(2) escape the simul.
(3) ???
(4) profit!
Wait, shouldn't we be worried? Once Mario discovers he's in a simulation, he'll create a paradox and escape the simulation! Donkey Kong too!
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50/50: Either we are or we aren't?
Think of it this way: we're getting pretty close to making a very realistic simulation. If you can imagine that we will be able to make a simulation, then it's natural to assume that, eventually, the simulation will be able to make a simulation. And that simulation can make a simulation. In addition, if we can make a single-layer simulation, we can make multiple copies of that simulation. So given an unknown number of possible simulated universes, the odds are increasin
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50/50: Either we are or we aren't?
Think of it this way: we're getting pretty close to making a very realistic simulation.
There are obvious flaws in the realism such as bumble bees being able to fly and the popularity of current pop music.
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That's an urban legend based on a misunderstanding of a scientific paper. What was proved was that if the bumblebee's wings were rigid, they wouldn't provide sufficient lift for flight, and that therefor, they must be flexible, although the researcher wasn't able to explain how flexible wings would provide enough lift. And yes, further research provided an explanation. As for current pop music, that's still a mystery.
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" standard model has made some predictions, cosmology can't really lay claim to that"
Wrong, Cosmology does have its standard model, it is called, get this, the Standard Model of Cosmology. And if you think the particle and field standard model is some sort of Holy Document, it is merely a collection of cobbled together mathematics that seems consistent (that we know). It was the craft of fitting what we could see in experiments with mathematics that at least did not contradict it and seemed produce, in inst
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The math was mostly invented after the justification for it ... it's a fit, not a prediction. One discarded parameter in general relativity being dis-discarded is not really a prediction.
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This is semantic quibbling.
Whether it's a prediction or not depends on which decade you're in. Certainly when Einstein introduced lambda it was curve-fitting. After he removed it, it became a discarded prediction. So when it's reinserted it's a prediction.
They're basically the same thing looked at from different perspectives. If you have a bunch of data and you PREDICT that an equation will match it, then you are testing your prediction. If you adjust it slightly to better fit the data, then you're cur
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AFAICS while the standard model has made some predictions, cosmology can't really lay claim to that. Cosmology seems to me a craft of fitting. Big bang was to fit red shift,
The big bang theory had a large number of consequences that later measurements showed correct, in particular, the cosmic microwave background is an observable consequence of the big bang, and nucleosynthesis predicts the relative abundance of the light elements which were synthesized in the big bang. https://phys.libretexts.org/Co... [libretexts.org]
inflaton/inflation was to fit CMB, dark matter was to fit galaxy rotation, dark energy was to fit accelerating expansion.
Well, dark matter is a pretty straightforward hypothesis: if trajectories we observe can't be fully explained by the gravitational effects of the stuff we see, it may be due to
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Fortunately big bang is enough to explain nucleosynthesis all by its lonesome, that doesn't require a singularity.
Singularity and CMB on the other hand required something entirely new to make it fit, inflation, which doesn't just roll out of general relativity and the big bang. The theory in the article tries to fit something other than inflation and uses dark matter as justification. Given the stretch which inflation clearly is, it might pass Occam's Razor as well or even better if it gets popular (unlikel
CMB [Re:With enough dimensions you can fit any...] (Score:4, Informative)
The existence of Cosmic Microwave Background is a consequence of the big bang. The average temperature of the CMB is a prediction that can be calculated from the big bang. The extraordinary uniformity of the average temperature at cosmologically-large distances across the sky, however, is not a prediction of the big bang, and is what inflation was proposed to account for. The even smaller deviations from complete uniformity of temperature is a measurement that may tell us which theory of inflation to look at.
Plausibly there might be some alternate theory than inflation to explain the uniformity of the CMB, but so far none have been hypothesized.
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So far none have had broad acceptance, you can find almost anything hypothesized ... and with a bit of effort and a couple extra fields plucked from the ether you can fit almost anything.
https://scholar.google.com/sch... [google.com]
Science? Or at least Math? (Score:2)
Or just publish or perish untestable "pass whatever you're smoking"?
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Damn, yer on to us. Those quantum theories we did back in the aughts and 1910s? Complete bunk, and they we not testable. Yet we somehow persisted and grew more exquisite untestable theories and then we ran into experimental evidence supporting them. Why did we collect that evidence? We were looking for the artifacts the theories said should be there. The nerve of those physicists publishing their "untestable" theories.
Re: Science? Or at least Math? (Score:3)
You think you're so clever bilking tax payers for research grants for "science". But if you were farmers instead of scientists you could have gotten 1000x more from corn and dairy subsidies.
Science does not say the Big Bang is the beginning (Score:4, Informative)
Science says that there is a state early in the big bang, where we have no clue what happened before. Why is it that so many people cannot deal with the unknown?
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Cosmology is not a science, it's a sport. Singularity has been winning for a while, but nothing lasts forever.
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Every human endeavor is a sport. What's your point?
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"Cosmology is not a science, it's a sport."
False choice, and also bullshit.
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The pursuit of science is literally the quest to discover the unknown. Whenever something is unknown, and we figure out that we don't know it, there is something inside us humans that is drawn to this. It's an irresistible force driving us to study, to learn, to theorize, until we have put that missing piece of the puzzle in its place. This is why the study of science exists...the need to *know*.
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Well, yes. But when you actually follow the scientific way, you do not just fill in things to fake-"know". (That approach is called "belief" and often comes in the form or religion and ersatz-religion.) Here, "The big Bang was the start" is a non-scientific and in fact anti-science statement, as it simply is a claim of truth without evidence. It is _very_ important to always understand the areas where we do not (hopefully "no yet") know.
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Well, yes. But when you actually follow the scientific way, you do not just fill in things to fake-"know". (That approach is called "belief" and often comes in the form or religion and ersatz-religion.) Here, "The big Bang was the start" is a non-scientific and in fact anti-science statement, as it simply is a claim of truth without evidence.
There is plenty of very convincing evidence for the big bang; it's not at all "non scientific", but to the contrary, is well supported by evidence.
Big bang cosmology really only goes back to the era of nucleosynthesis (the "First three minutes," to use the phrase in the book of that title.) You may be thinking of the part before that. Eventually, going backwards, you get to the era of the quark-gluon plasma, and before that the density where quantum gravity needs to be taken into account, and we don't have
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Unless you can prove that there's no way to know, then your question needs refinement. And proving that is extremely difficult.
OTOH, a lot of people *do* find it difficult to accept that there are a bunch of things we are uncertain about. That's definitely a true observation.
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Oh, I am not advocating to stop looking. Looking, modelling and trying to understand is important. But you always need to be clear on what you actually know and what not or Science goes out the window.
OTOH, a lot of people *do* find it difficult to accept that there are a bunch of things we are uncertain about. That's definitely a true observation.
And you are already using the weakened version here. There are plenty of things we do not know anything (!) about. Personally, I do not understand the stance of those people that cannot deal. I never had any issues with the unknown. To me it always was a case of "venture there if interested or there is a need,
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The standard model suggests that time itself began with the Big Bang. https://philsci-archive.pitt.e... [pitt.edu] If this is correct, then it's meaningless to talk about "before" the Big Bang. So it's not just an aversion to the "unknown," but suggesting that things existed before the Big Bang, is a contradiction to the current understanding of cosmology. When a theory comes along that contradicts what scientists generally agree upon, the threshold is very high for any theory that upends that model.
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The standard model is a model, not reality and does not apply close to the big bang. Hence there is actually no threshold at all to overcome. You just failed to understand how Science works. Incidentally, your own language gives you away: The standard model does not model the Big Bang and anything you think it "suggests" is just a misinterpretation on your part. A model either models something or it does not. It does not "suggest" things. Sure, you can _speculate_ about things based on a model, but that doe
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The standard model suggests that time itself began with the Big Bang. https://philsci-archive.pitt.e... [pitt.edu]
I would not rely on an essay by a professor of philosopher to clarify the standard model of big-bang cosmology, but I do point out that the very first paragraph says "However, not everybody agrees with this verdict."
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Not everybody agrees with *any* scientific finding.
sometimes your theory is wrong (Score:1)
Re:sometimes your theory is wrong (Score:4, Insightful)
Hmmm....good point. One's theory is wrong. What does one do? Come up with a new theory. Hah, you've solved the problem, theories are dime a dozen. Maybe you could tell the physicists their theories are wrong and show them how to correct them. Should be easy, you could probably do it in an afternoon.
Every attempt at changing Einstein's gravity has failed. That does not mean scientists have not and are not currently trying. Newton's theory was not wrong, his mathematics was spot on. The interpretation of that theory was wrong is many instances and required us to limit its area of use, but we still use it. We build bridges using it. Einstein did not do away with Newton's math, he improved it. And just so you know, Newton's constant for gravitation is still used in modern relativity.
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at a certain point this gets ridiculous. Why can't general relativity plot the rotation of stars? Must be that 90 percent of everything is invisible. Can't find the invisible stuff? Must be because the invisible stuff was made before everything else.
C'mon. These are definitely not the first people to posit a cyclic universe. It's an open question whether the universe is closed, flat, or open and bright sparks are busy trying to find ways to measure the overall curvature. It's quite reasonable to hypothesize "if the universe is closed and cyclic, what might be a predictable effect?"
What these people are saying is "We can't explain the observed rotational curves and gravitational lensing. If the universe is cyclical, here's a plausible idea of what might
Weighing more or less the mass of an asteroid (Score:2)
Is that a European asteroid, or an African asteroid?
But seriously, asteroids come in a wide range of sizes.
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If dark matter were asteroids, we'd see trillions of times more asteroids than we actually observe.
They would occlude stars and emit IR. Many would fall into stars, creating stars rich in iron and silicon in their outer layers.
We see none of that.
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If dark matter were asteroids, we'd see trillions of times more asteroids than we actually observe. They would occlude stars and emit IR. Many would fall into stars, creating stars rich in iron and silicon in their outer layers.
Actually, not necessarily. If they're large enough, the surface area to mass ratio is quite small, so they wouldn't emit enough IR (per unit mass) to see. And you wouldn't see them occlude stars because they are too small-- they'd have to be planet sized to occlude stars, and if they are planet sized, they'd be very sparse. And, as for falling into stars, quoting Douglas Adams, "space is big".
But that last factor is really it. It's not so much falling into stars now, but, why weren't the heavy elements (stu
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The problem is that if it were the mass of an asteroid originally, it would be rapidly evaporating and emitting radiation now.
I suspect that the actual answer is that small black holes can't completely evaporate. Once they get small enough they can no longer capture have of a pair of virtual particles, so they stop evaporating. And those are the black holes that are "dark matter". They're black holes, alright, but they're of minimal size. Too small to eat anything. Which means that they can travel thro
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The problem is that if it were the mass of an asteroid originally, it would be rapidly evaporating and emitting radiation now.
If the mass of the black hole is greater than about 10^11 kg, it wouldn't have evaporated in the lifetime of the universe to date. Seems like a lot, but 100 million tons is small for an asteroid.
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Ok, but why would they all be the same size? If you're going to have the big bang generating massive asteroids, then I'd expect a range of sizes, with some being a lot smaller than others. So you should be able to detect them spewing radiation. Unless you've got some reason for a particular minimum size. (E.g. it only happened when things were at a particular density that yielded a certain Schwarzschild radius.)
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Ok, but why would they all be the same size? If you're going to have the big bang generating massive asteroids, then I'd expect a range of sizes, with some being a lot smaller than others. So you should be able to detect them spewing radiation. Unless you've got some reason for a particular minimum size. (E.g. it only happened when things were at a particular density that yielded a certain Schwarzschild radius.)
Since I don't know the model of how the big bang generates black holes, I don't have a good guess as to the size range.
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So black hole evaporation time is based on the cube of the mass, about 3.396*10^-16*(Mass in kg)^3 seconds. The time transitions quickly from "basically instantly" to "basically never". So a black hole weighing about 1.0861*10^11 kg would evaporate before humans existed, and one weighing 1.0862*10^11 kg would evaporate 3.8 million years later, by which time humans might not exist.
I'm not a statistician nor astronomer so I can't say what that means in regards to being able to see one now with our tech. Also,
"If this hypothesis holds" (Score:1)
That's a very big IF.
We are made of evaporated black holes! (Score:2)
If I understand correctly in this model all the photons and particles result from the too small black holes which have evaporated into photons and particles, the rest of matter would still be trapped in larger black hole. This is a refreshing perspective of our origins.
Remains just to explain 2/3 of the rest of the universe, dark energy.
LiveScience does not know what space-time means? (Score:2)
"The Big Bang may not have been the beginning of the universe..."
For some redefining of "beginning", "universe" and/or "Big Bang" that could be true, but for a "universe" of space-time as we know it, the "Big Bang" is the "beginning of the universe". That doesn't mean there isn't something outside the scope of space-time, but "beginning" has a particular meaning with respect to "time" that is defined within the "universe". Not very sciencey, this "LiveScience".
Black holes are detectable (Score:2)
So whether or not they existed "before" the Big Bang (whatever that means, since time was created with the Big Bang), we should be able to "see" them as we can see "regular" black holes.
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"since time was created with the Big Bang"
If time didn't exist then the big bang couldn't have happened as changing state requires time to happen in. The universe (or whatever it was) would be in suspended animation.
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There is certainly debate among scientists on this topic.
Not sure if this idea works thermodynamically (Score:2)
Some physicists these days like Sean Carroll think that the arrow of time and causality arise thermodynamically. All fundamental physical laws are time-reversible, so the only way for there to be a difference between "forward" and "backward" in time is because one direction was closer to the Big Bang than the other. Increases of entropy are the engine of time asymmetry and causation; there's no other way for us to sensibly say the past causes the future (and not vice versa) since at a fundamental level th
Little black holes flying around everywhere? (Score:2)
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Cosmologically, it is a lot harder to have massive objects, moving at different speeds and directions, actually hit. Even when they get close, the speeds involved often just mean they careen off in different vectors. But if they do manage to come together just right, they are just as likely to form an orbit around it other. It would be easier for you to hit an arrow, with ANOTHER arrow, while both are in flight than for a random object to slam into another random object on such a scale.
But since the univ
Tau zero? (Score:1)
This reminds me of hard sci-fi book Tau Zero from Poul Anderson
Didn't we agree big bang is t=0 (Score:1)
Didn't we agree that big bang is when time started or came into existence and there's absolutely NO 'before the big bang' ?
Because otherwise it's all turtles..
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I guess you missed the thing about the gravitational waves possibly being observable. You know, if you ignore half of a story, things will forever looks incomplete and meaningless to you.
Re:Dark matter? (Score:5, Insightful)
Galaxies that should fly apart do not. Why is that? The only thing we know that keeps galaxies shit together is mass and mass creates gravity. Hence there must be a lot of mass we cannot see. So physicists put a pin on the map and call it dark matter. Yes, we do not understand it in the sense we cannot create it in a lab and test its properties.
Just to explain the obvious to you. Do you know what an electron is? Yes, well then you are smarter than all the physicists who merely posit a theory explaining its properties. They cannot tell tell you precisely what it or any other kind of matter is, yet they seem to have built a coherent picture of the universe.
Science is like that. Your idea of science is right out of the 1600s that requires a definition and hence can say what is and what is not. However, we have learned since that those definitions do not define their terms, if they did, there'd be an infinite regress.
To give you an analogy, you are probably satisfied with Euclid's idea of geometry. That worked until Hilbert came along and "redefined" geometry. People like Poincare, who was a brilliant mathematician, and Frege, a brilliant logician, had the notion that math proceeded from definitions. When Hilbert defined his geometry system, Poincare threw a sprocket and complained there were no definitions. Hilbert's response was that it was the interconnections between the elements of his system that provided the "definitions", if you still need them. That does not prevent us from using Hilbert's geometry or defining new geometries.
A system of axioms and rules is just that, deductions follow. More cannot be said unless you include a collection of models. Which model is the true model? Answer: they all are. A statement derived in the system is either true or false of a model. Similarly, a statement in physics, written in the language of mathematics, and stemming from some assumptions (axioms), is either true or false of a model.
What the physicists are saying is that the statements about mass and galaxies and gravity make sense in a model that included primordial black holes. Is that a model of our Universe? We don't know but they have a way of testing that hypothesis. Are the statements contradicted by the model? Not yet.
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but they have a way of testing that hypothesis.
Gravitational waves are one way to test the theory.
Looking for black holes would be another.
TFA says they are big enough not to decay in the universe's lifetime, which means at least 200 million tonnes. There would have to be quintillions of them in our galaxy. They would be millions of times more common than stars. Some of them would merge and grow.
We would see them everywhere through lensing events, radiation from their accretion disks, and Doppler effects on stars and gas clouds.
Yet, we see nothing like
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A 200 million tonne black hole would have a diameter which is a tiny fraction of the size of a proton. Its cross section would be so small that it would be unlikely for anything at all to fall into it, much less merge with an equally small black hole. It's doubtful anything would be captured into orbit around it to form a disk, and any lensing would also be as negligible and undetectable as that caused by an asteroid.
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If it moves fast enough not to get captured. If it orbits inside the diameter of a star for a bit then eventually there is no star any more.
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I'm too lazy right now to search for it properly, so I'll let ChatGPT sum it up:
Summary:
If a small primordial black hole were to be caught inside a star, its growth rate would be slow, especially if its initial mass is small. The timescale for significant growth might be extremely long, potentially longer than the star's lifespan, meaning the PBH might only grow modestly before the star's eventual demise
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You are only considering normal stars.
But the Milky Way contains a billion neutron stars.
Neutron stars have a density of 600 trillion tonnes per cubic meter.
A black hole of a billion tonnes or so would rapidly lose momentum from tidal forces when moving through something so dense and settle to the center, where immense pressure would push the neutrons into it.
Since the Milky Way would have to contain quintillions of these billion-tonne black holes to account for the missing mass, each neutron star would lik
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Show us your math for the capture rate of a neutron star for black holes of the expected density in the local Universe, and the expected lifetime of neutron star for this event to occur. Because you would have had to do this (or found someone else who had) to know that you conclusion is not wrong.
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Show us your math for the capture rate of a neutron star for black holes
The Milky Way has about 100 billion stars. [source: Google]
The Milky Way has about one billion neutron stars. [source: Google]
The Milky Way has a mass of about 1.5 trillion solar masses or 3e39 tonnes. [source: Google]
If 80% of that is black holes, each with a mass of 200 million tonnes, that would be 1.5e31 black holes.
According to this webpage: Stellar collisions [wikipedia.org], there is a star merger in the Milky Way every 10,000 years.
Neutron stars are 100 times less common, but the primordial black holes are 1e20 mor
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Dark matter has to have more mass than normal matter, so presumably there have to be lots of these asteroid mass black holes. Does that mean we would likely have these black holes passing through the earth, or at least the sun, unnoticed on a very regular basis?
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IIRC, yes. Such a black hole would have such a small cross section that it could pass through the earth without actually colliding with anything.
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Re: Dark matter? (Score:2)
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+1 insightful.
Yes, saying that the density of dark matter is high compared to the average density of non-dark matter does not mean that the density is high in any absolute sense, because the average density of non-dark matter is extremely low.
Also, stars and gas in our galaxy mostly forms a disk, while dark matter, being apparently non-interacting (or only weakly interacting), is spherically distributed around the galaxy. So, the dark matter occupies a much larger volume of space.
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dark matter, being apparently non-interacting (or only weakly interacting), is spherically distributed around the galaxy. So, the dark matter occupies a much larger volume of space.
But if dark matter were black holes, it would not be spherically distributed.
Tidal forces would pull the BHs into the same disk as the stars.
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Well, this must be a well know result then. You can't be the only person to notice this effect. So kindly provide a link showing us that this is do.
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dark matter, being apparently non-interacting (or only weakly interacting), is spherically distributed around the galaxy. So, the dark matter occupies a much larger volume of space.
But if dark matter were black holes, it would not be spherically distributed. Tidal forces would pull the BHs into the same disk as the stars.
I'd be interested in seeing that calculation.
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Well, this must be a well know result then.
Yes, it is very well known.
An object orbiting a spherical planet will be pulled into an equatorial orbit. All of the moons in the solar system are in equatorial orbits, or close. The quadrillions of particles in Saturn's rings are also in equatorial orbits.
An object orbiting a disk is pulled into an equatorial orbit even faster, for obvious reasons. When it is above the disk, it's pulled down. When it is below, it's pulled up.
But what would happen if the object was a point? How would that change the gravita
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A 200 million tonne black hole would have a diameter that is a tiny fraction of the size of a proton. Its cross section would be so small that it would be unlikely for anything at all to fall into it, much less merge with an equally small black hole. It's doubtful anything would be captured into orbit around it to form a disk, and any lensing would also be as negligible and undetectable as that caused by an asteroid.
A 200-million tonne BH would have a Schwarzschild radius about half that of a proton.
Half isn't a "tiny fraction".
Also, 200 million tonnes is the lower-bound. Anything smaller would've decayed long ago.
Above 500 million tonnes, and they're bigger than protons.
A 500 million tonne BH in the center of a neutron star would grow rapidly. It would triple its mass just by sucking up one cubic centimeter of matter and grow exponentially.
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but they have a way of testing that hypothesis.
Gravitational waves are one way to test the theory.
Looking for black holes would be another.
TFA says they are big enough not to decay in the universe's lifetime, which means at least 200 million tonnes. There would have to be quintillions of them in our galaxy. They would be millions of times more common than stars. Some of them would merge and grow.
We would see them everywhere through lensing events, radiation from their accretion disks, and Doppler effects on stars and gas clouds.
Yet, we see nothing like that.
Do you have a citation for a paper showing these claims in a reasonably rigorous manner? Or are you just gassing?
Just saying "Some of them would merge and grow. We would see them everywhere through lensing events, radiation from their accretion disks, and Doppler effects on stars and gas clouds.Yet, we see nothing like that." doesn't make any of the words true. You actually have to show with real physics and astronomical considerations that these suppositions really work out as you assert.
There is pretty go
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Here is an actual paper discussing the constraints so far developed on the prevalence asteroid size black holes [scipost.org] . There are many others, like this one [arxiv.org] and so one, googling will bring up many and their references will point to many more.
But what you won't find yet is a paper that makes the conclusions that you seem to believe have been firmly established -- that the possibility of primordial black holes as being a significant contributor to dark matter has been ruled out entirely. If any such papers have bee
Re: Dark matter? (Score:2)
The only thing we know that keeps galaxies shit together is mass and mass creates gravity.
There is no such thing as gravity. It's just curved space-time. And it's possible that Einstein's equations for this curvature just need an additional term to cover cases involving large distances and/or masses.
Einstein might have been correct in initially proposing a Cosmological Constant. But of a different form and for different reasons.
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There is no such thing as gravity. It's just curved space-time.
Are you ruling out gravitons [wikipedia.org]? If so, why? Is there more than a just reasonably based hatred of string theory?
Dark thoughts - Margin of error (Score:2)
These 'news' stories should be classified 'speculative science' because we don't have any way to know how close they are to any possible real factual event.
These are all guesses at this point with an unknown and unquantifiable error factor.
Re: Dark matter? (Score:2)
Re: Dark matter? (Score:4, Insightful)
Dark matter was never indented to be a real and definable thing. Once we figure out where thr extra mass and gravity in the universe comes from we wilk give it a proper descriptive name. It isn't a religion. It is science pointing at somewith we don't understand and saying effectively: oh, well will you look at that!
Re: Dark matter? (Score:2)
gravitational waves generated during the black hole formation process might be detectable by future gravitational wave observatories,
So, they actually haven 't been detected yet. Time to scrape togeter a few billion dollars to build them.
Gravitational waves [Re:Dark matter?] (Score:3)
Those gravitational waves are the unexplainable thing that dark matter was invented to account for.
No.
Gravitational waves are an unavoidable consequence of the general theory of relativity, they are not in any way "unexplainable", and were understood decades before anybody hypothesized dark matter. (In fact, they are an inevitable result of any theory of gravity in which gravity does not have an instantaneous effect at a distance.)
Dark matter was originally invented to account for the rotation curves of galaxies (essentially, the fact that stars in the outer fringes of galaxies seem to be bound to galaxi
He only ignored the parts he didn't understand. (Score:2)
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Yep, looks like it. And also a Dunning-Kruger case, because he seems to think he is really smart.
Re: Dark matter? (Score:2)
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i thought gravational waves were created by massive catastrophes like supernovaes or two stars merging or two black holes merging, stuff like that
Not a physicist, but as I understand it any accelerated mass creates gravitational waves. Existing detectors aren't however sensitive enough and can only detect really strong ones, like the ones created by supernovae or other very violent events.
As a matter of fact, (AFAIK) the first (indirect) confirmation of gravitational waves didn't come from either supernovae or merging black holes. It came from studying the decay of the orbital period of binary pulsars. As the two pulsars in a binary system rotate aro
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Yes, pretty much.
The other thing is that gravitational wave detectors are still pretty primitive. Apparently people though for the longest time they were not feasible at all. Hence significant improvements are to be expected.
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So, here's yet another theory that can never be proved, untestable, with no evidence to explain the existence of a material...
I wouldn't go so far as to call it a theory yet. It's a hypothesis and it makes some predictions we could test. Here's at least three ways we might test it.
As TFA and others have pointed out, it might generate gravitational waves. We can detect some of these already so it's possible we might detect the predicted waves in the future.
Swarms of primordial black holes ought to have predictable behavior during galaxy collisions. From gravitational lensing, we have some ideas how dark matter behaves during the co
Great Arkleseizures (Score:2)
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