A hidden population of black holes, born less than one second after the Big Bang, could solve the mystery of dark matter
- The nature of dark matter—the invisible substance that keeps galaxies intact through its gravity—is a profound cosmic puzzle.
- Many researchers suspect that dark matter is made of "wimps": particles with mass that manage weak interactions, and they search for them in experiments. However, so far no such wimps have been found.
- "Primordial" black holes that may have formed shortly after the Big Bang are an alternative candidate for dark matter. But they too have escaped detection so far.
- Additional evidence for the existence of primordial black holes may appear in new data coming from gravitational wave detectors and other observatories. If their existence is confirmed, these objects could solve the mystery of dark matter, and crack several more cosmic puzzles.
More than a billion years ago, Mon Black holes In the distant universe they circled each other in a deadly dance until they merged. This spiral collision was so violent that it shook the fabric of space-time, and sent disturbances - gravitational waves - that spread out at the speed of light, like ripples throughout the cosmos. In September 2015, after traveling more than a billion light years, these ripples washed over our planet, and were recorded as a "chirp" in the sensors of the Advanced Gravitational Wave Observatory using laser interferometry (Advanced LIGO).
This was the first direct detection of gravitational waves, and this observation confirmed Albert Einstein's century-old prediction of their existence. However, this tweet showed that each of the black holes that caused this merger were 30 times heavier than the Sun. That is, their masses were two to three times greater than the masses of ordinary black holes born from supernova explosions of massive stars. These black holes were so massive that it's hard to explain how they even formed from stars. Moreover, even if two such black holes did form independently from the deaths of very massive stars, they would have to find each other and merge—an event whose probability of occurrence is incredibly low at the current age of the universe. It would therefore only make sense to suspect that these massive black holes were formed by some other, more exotic process, possibly unrelated to the stars at all. It is possible that LIGO not only detected gravitational waves, but also lifted the lid on something much more amazing: black holes that predate the formation of the stars themselves.
Although such "primordial" black holes have never been observed before, there are several theoretical models that raise the possibility that they could have formed in astronomical numbers from the hot, dense plasma that filled the cosmos less than a second after the Big Bang. This hidden population may solve some amazing mysteries in modern cosmology. In particular, primordial black holes could be one of the components, if not the only component, of the dark matter – The invisible 85 percent of matter in the universe that acts as a gravitational glue that keeps galaxies and galaxy clusters intact. Further studies using LIGO and other facilities will soon put these ideas to the test, possibly revolutionizing our understanding of the cosmos.
The fall of the machos, the rise of the wimps
Black holes would seem like the perfect candidates for dark matter, since they emit no light at all. Indeed, along with other dark bodies such as planets and brown dwarfs, they were proposed a long time ago as a solution to the dark matter problem: machos, English acronyms for "compact and massive halo bodies" (Massive Compact Halo Objects). If such bodies are found both in the globular halos surrounding each galaxy and near the center of the glow of each galaxy, their gravitational pull could provide an explanation for the inconceivable motions of the stars and gas that astronomers observe in observations of the fringes of galaxies. Simply put, the galaxies appear to be spinning around at too high a speed for the apparent mass of the observed stars to keep them intact. The dark matter provides the extra attraction that will prevent the swirling galaxies from throwing their stars outwards.
If machus make up most of the galaxy's dark matter, then they must also provide an explanation for other observations. Whatever dark matter is, it shapes the largest structures of the universe, determines the origin and growth of galaxies and clusters and superclusters of galaxies. These bodies are formed by the gravitational collapse of gas clusters within dark matter halos. The cosmologists precisely mapped the spatial distribution of these clusters using latitudinal and depth surveys of galaxies and checked their correlation with tiny temperature fluctuations that appear in the cosmic microwave background radiation (CMB), the residual glow after the Big Bang, filling the entire sky. The diffuse mass of dark matter in large galaxies and large clusters also warps space and distorts the light coming from very distant objects in the background - a phenomenon known as gravitational dimming.
However, the machoi hypothesis decreased from its greatness ten years ago, when it became clear that machoi did not appear in indirect and uncoordinated searches conducted to find them. In particular, the search conducted by astronomers should be noted micro-recycling - A type of gravitational clouding in which a black hole, brown dwarf or even a planet passes by a star in the background and increases the star's light for some period of time. Several micro-scanning surveys spanning several years and surveying millions of stars in the Large and Small Magellanic Clouds, the main satellite galaxies of the Milky Way, have found no evidence that machus make up our entire galactic halo. These results were conclusive enough to rule out the possibility that machos up to about 10 solar masses in size are the main component of dark matter. At the time these surveys were conducted, theorists built a set of arguments for an alternative hypothesis - WIMPs (literally: "weak"), English acronyms for particles with mass that conduct weak interactions (Weakly Interacting Massive Particles).
The existence of the wimps has been predicted by certain extensions of the standard model of particle physics, but they remain elusive, at least as much as the machos. As of today, no evidence of their existence has been found despite decades of searches with the help of particle accelerators, underground detectors and space telescopes. In the face of the increasingly negative results piling up in the search for wimps, some researchers have begun to reconsider the macho hypothesis, focusing specifically on primordial black guys. However, what process could have scattered these strange objects throughout the visible universe, and how did they manage to escape detection for so long?
Black holes from the big bang
Physicists Bernard Carr and Stephen Hawking proposed the idea of primordial black holes in the 70s. They looked at the possibility of black holes whose masses are smaller than the mass of Mt. Such tiny black holes would have already evaporated and disappeared within the time frame of the age of our universe, almost 20 billion years, through a process rooted in quantum mechanics - a process discovered by Hawking and hence named "Hawking radiation". But they also explored the possibility that more massive, non-evaporating black holes make up the missing material in galaxy clusters.
The possibility that massive primordial black holes might make up most or even all of dark matter was further explored in the 90s, based on the idea of the Cosmic inflation, an idea first proposed by physicist Alan Guth in the early 80s. Inflation is an assumed phase of capital expansion that took place immediately after the Big Bang. within 10-35 seconds, two points that were less than an atomic radius apart were separated by up to four light-years, like the distance between the nearest stars. Moreover, during inflation, tiny quantum fluctuations are magnified to macroscopic scales by the rapid expansion, seeding the growing universe with under- and over-density regions of matter and energy, from which all cosmic structures eventually emerged. Strange as it may sound, the theory of inflation has received considerable support from observations of such fluctuations in the density of the cosmic background radiation.
In 1996, one of us (Garcia-Balido), in collaboration with Andrei Linda of Stanford University and David Wandes of the University of Portsmouth in England, discovered a way in which inflation could create sharp jumps in the spectrum of density fluctuations in the early universe [see box]. In other words, we have shown how quantum fluctuations that have been massively amplified by inflation can naturally create superdense regions that will collapse to form a population of black holes less than a second after inflation ends. Such black holes would therefore behave like dark matter and be the main component of the matter content of the present-day universe. This model created a population of black holes with the same mass, determined by the amount of energy inside the collapsed region. At this point, many other groups began to explore these ideas within various inflation models.
In 2015, we both (Cels and Garcia Belido) proposed a scenario, similar to the 1996 scenario, in which these primordial fluctuations would have a broad jump in their energy densities and spatial size, a jump that would result in the creation of black holes with a wide range of masses. One of the important consequences of this scenario is the fact that large density fluctuations collapse when they are spatially close to each other, forming clusters of black holes with different masses - from one-hundredth the mass of our Sun to 10,000 times its mass. Within half a million years from the Big Bang, any growing and developing cluster could contain millions of primordial black holes in a volume whose diameter does not exceed a few hundred light years.
Such clusters of primordial black holes could be dense enough to explain LIGO's mysterious black hole mergers, because without these clusters, we wouldn't expect such mergers to occur routinely. From time to time, the trajectories of two primordial black holes within a cluster can cross, so that the two objects will be bound together by gravity. They will then approach each other in a spiral motion for a time that can reach millions of years, radiating gravitational waves, until they merge. In January 2015, we actually predicted that LIGO would detect gravitational waves from such massive mergers—waves identical to those that LIGO did detect later that year. Our estimate of the rate of merger events within primordial black hole clusters fits precisely within the limits set by LIGO. If LIGO and other similar facilities detect many more mergers in the coming years, it may be possible to determine the mass range and spin rate of all unmerged black holes. Statistical analysis of black hole mergers will provide essential information to check if they are indeed of primordial origin.
One of the significant features of this scenario is the release from the constraints previously imposed on the machos by the gravitational micro-mass experiments - constraints that eliminated the possibility of black holes up to 10 solar masses in size as the main component of dark matter. If primordial black holes do exist and indeed have a wide range of masses, only a small percentage of them will be visible to the eyes of these microcosm experiments, and the vast majority will remain invisible. And if primordial black holes are clustered, this organization means there is a less than one in 1,000 chance that a cluster will happen to be within line of sight of the stars in nearby satellite galaxies, which are being monitored for micro-clogging events.
To avoid this phenomenon, one can look for micro-cleaning events in other places in the sky, look for increased light coming from stars in the neighboring galaxy to the Milky Way, Andromeda, or even from quasars in very distant galaxies. In this way, it will be possible to check a much larger volume of galactic halos and look for signs of machos in them - that is, for primordial black holes. Recent observations raise the possibility that even if machus whose mass is up to 10 solar masses do not make up the entire halo of an average galaxy, still machus whose mass ranges from a tenth of a solar mass to a few solar masses could easily account for about 20% of the mass In a typical galactic halo. This value is consistent with our wide mass spectrum primordial black hole scenario.
Simply put, it is still impossible to rule out the possibility that dark matter is made mostly of primordial black holes. And the truth is that this proposed scenario could unravel several other cosmic mysteries related to dark matter and galaxy formation.
Many problems, one solution
Clusters of primordial black holes could shed light on the problem known as "The missing satellite problem” – the apparent absence of "dwarf" satellite galaxies that should have formed around massive galaxies like our Milky Way. Recent simulations that have modeled the cosmic distribution of dark matter are able to accurately reproduce the observed large-scale structure of the universe, where haloes of dark matter attract galaxy clusters and form giant filaments and sheets surrounding vast, lower-density voids. However, on smaller scales these simulations predict the existence of several dark matter subhaloes orbiting massive galaxies. Within each of these subhaloes is supposed to be a dwarf galaxy, and hundreds of them are supposed to surround our Milky Way. But the number of dwarf galaxies found by the astronomers is much smaller than expected.
There are many possible explanations for the problem of the missing satellite - mainly the idea that the simulations fail to fully describe the effect of normal matter (hydrogen and helium in stars) on the formation and behavior of the dwarf galaxies that are supposed to exist according to the predictions. Our scenario raises the possibility that if accreted primordial black holes make up most of the dark matter, they will be the main component of the subhaloes surrounding our Milky Way, swallowing some of the normal matter and slowing the rate of star formation in the subhaloes. Moreover, even if these subhaloes were to produce stars vigorously, these stars could easily be ejected from their contents by close encounters with massive primordial black holes. Both of these phenomena will significantly reduce the brightness of the satellites, making them very difficult to detect without super-sensitive wide-field cameras. Happily, such cameras exist today, and astronomers have already used them to discover dozens of ultra-dim dwarf galaxies that surround the Milky Way. The amount of dark matter these objects contain appears to be several hundreds of times greater than in the luminous stars they contain, and our model predicts that there are thousands more like them around our galaxy.
The simulations also predict a population of intermediate-sized galaxies, more than dwarf galaxies and less than massive galaxies. Such objects should be too large to disappear, as they would be large enough to easily form stars, and should also be easily seen. However, they did not appear in the searches conducted by the astronomers near the Milky Way. This "too big to disappear" problem has a similar solution to the missing satellite problem: massive primordial black holes at the cores of medium-sized galaxies may cause stars and star-forming gas to be ejected from these objects, rendering them virtually invisible in most surveys.
Primordial black holes could also settle the question of the origin of supermassive black holes (Supermassive Black Holes, SMBH). The weight of these monsters ranges from millions to billions of solar masses and they are found in observations at the center of quasars and massive galaxies in the very early stages of the universe's history. However, if these SMBHs were formed and grew from the gravitational collapse of the first stars in the universe, they should not have accumulated such enormous masses in such a relatively short time - less than a billion years after the Big Bang.
In our scenario, although most primordial black holes have only a few tens of solar masses, a very small percentage of them will be much heavier, in the range of hundreds to tens of thousands of solar masses. These monstrous objects, born less than a second after the Big Bang, could therefore function as giant seeds from which the first galaxies and quasars grew, objects that quickly develop SMBHs at their centers. Such seeds could also explain the existence of intermediate-mass black holes, with a thousand to a million solar masses, observed orbiting SMBHs and at the centers of globular star clusters. In short, primordial black holes may be the missing link between ordinary stellar-mass black holes and SMBHs. The observational arguments in favor of this scenario are accumulating rapidly: unexpected sources of X-ray abundance have recently been identified in the early universe, and the simplest explanation for their existence is large numbers of primordial black holes producing X-rays as they devour gas, less than a billion years after the Big Bang.
see in the dark
Although primordial black holes can solve both the dark matter mystery and many other stubborn problems in cosmology, it is still not the end of the game. Other models and explanations are also possible, and future observations should allow us to choose between the alternatives. Indeed, in the coming years some observations will be able to examine the primordial black hole scenario [see good to know]. These observations include the detection of ultra-dim dwarf galaxies, the effect of primordial massive black holes on the positions of stars in the Milky Way, the mapping of neutral hydrogen during the first epoch of star formation, and the study of distortions in the cosmic background radiation.
Apart from these experiments, we now also have a completely new tool for revealing the mysteries of the universe - the Advanced LIGO detector and other detectors of gravitational waves. If LIGO has indeed detected a merger of two members of a hidden population of primordial massive black holes, then we should expect many more such mergers to be discovered in the coming years. In June 2016, Advanced LIGO scientists presented to the community a second detection of gravitational waves, emitted during the merger of two black holes, with 14 and eight solar masses, respectively, as well as a tentative hint of another merger of black holes with 23 and 13 solar masses. As we were finishing writing this article, they claimed to have identified six more merger events. These detections raise the possibility that black binaries are much more common than expected and that their mass distribution is much wider, things that are consistent with our scenario for massive primordial black holes.
The combination of these experiments and observations could confirm the existence of primordial black holes and their possible connection to the missing matter in the universe. Soon we will no longer be in the dark about dark matter.
Good to know - is dark matter made of primordial black holes?
These observations will determine:
1. Detection of more gravitational waves
Gravitational wave detectors such as the Advanced Gravitational Wave Observatory using laser interferometry (Advanced LIGO) in the USA and the Advanced Virgo in Italy are supposed to detect more mergers of black holes. The detection of a larger than expected number of black hole mergers would be a clue pointing to a primordial origin, but this detection by itself would not be able to prove that primordial black holes make up the dark matter. Proof of this will have to come with corroboration by other observations. Ultimately, the detection of a black hole whose mass is smaller than the so-called "Chanderskar limit" (1.45 solar masses), below which stars cannot become a black hole, would be an unequivocal signal that it is a primordial source. Happily, LIGO may very soon reach a sensitivity that would allow it to detect such a black hole, if its companion is more massive (more than 10 solar masses). Finally, on cosmological scales, an abundance of binary black holes will produce a background of scattered gravitational waves, detectable by The space antenna using laser interferometry (LISA) that will be placed in space and with the help of pulsar timing arrays that will be placed on the ground.
2. Discovery of more ultra-dim dwarf galaxies
In 2015, astronomers discovered with the help of data from the "Dark Energy Survey" collaboration (Dark Energy Survey) dozens of ultra-dim dwarf galaxies in the galactic halo, a finding that raises the possibility that perhaps hundreds of those dwarf galaxies that are composed mainly of dark matter orbit the Milky Way. If dark matter is made from primordial black holes, then most of them should be found inside such dwarf galaxies, a large number of which will be detectable by future instruments placed in space, such as the Euclid mission (Euclid) of the European Space Agency and the Wide-Field Infrared Survey Telescope (WFIRST) of NASA.
3. Measuring changes in the position of stars
The European Space Agency's Gaia mission, now underway, is measuring the positions and velocities of about a billion stars in the Milky Way with unprecedented precision. These measurements may reveal the presence of many isolated massive black holes through the slight changes these objects create in the motions of neighboring stars.
4. Mapping the neutral cosmic hydrogen
Before and during the formation of the first stars, the universe consisted mainly of neutral hydrogen, which emits characteristic radiation in radio waves whose wavelength is 21 centimeters. already in 2020, The square kilometer array (Square Kilometer Array, SKA), which is planned to be the largest radio telescope ever built, will begin scanning the entire sky and mapping this 21-centimeter signal. The accumulation of matter by primordial black holes creates strong X-ray radiation, which ionizes the surrounding neutral hydrogen and leaves a mark on this 21-centimeter map, which spans the entire sky. SKA will therefore be able to detect the presence of primordial black holes, if they do explain dark matter.
5. Search for distortions in the cosmic microwave background radiation
X-rays from primordial black holes devouring gas and dust in the early universe are also supposed to induce distortions in the spectrum of the cosmic microwave background radiation. The importance of this phenomenon is still controversial, especially in models where primordial black holes are grouped in dense clusters. Nevertheless, NASA proposed an idea called the Primordial Inflation Explorer (PIXIE) mission, to accurately measure such distortions, which should impose strong constraints on models of dark matter made of primordial black holes.
69 תגובות
I realised. We'll leave it in "requires review" for now.
Raphael
You're right, and it really is a shallow approximation. But that describes the principle.
There is a physical concept called proper time, which is the time that measures each particle. That is, this is the time each particle will see on its wristwatch. This wristwatch started working 13.8 billion years ago.
This is also very superficial of course. I don't think there are particles today that last that long.
I'm sure that Albenzo will explain much better, but there is nothing illogical here.
Miracles
This is too superficial a method that does not take into account the distortions created by gravity which had a very large effect at the beginning of the universe, nor the speed at which the bodies move in the universe. I didn't just ask what clock they measure by because the theory of general relativity revealed to us that in fact every particle in the universe has its own private clock.
Raphael
Crudely, it is easy to extend the age of the universe. We see that distant bodies move away from us, at a speed that is directly proportional to the distance from us. Therefore, if you divide the distance to some particular object by its speed, you will get a constant time. This constant time is the age of the universe.
Regarding the first question - all these times and in general everything that happened, is a theory. The theory is based on many observations, such as the cosmic background radiation. In particle accelerators like the LHC we study how particles behave in extreme conditions, which are similar to those at the time of the Big Bang.
One of the assumptions is that all points in the universe are equal. That is - intelligent beings on a planet 40 billion light years away will see what we see.
I am asking a question that I have asked before but I did not receive a satisfactory answer for me.
How is it possible to measure time at the beginning of the universe and be more precise to the 10th power of minus 36 of a second when the space-time curvature was so extreme?
Even today it is not clear how one can say that the big bang happened 13.8 billion years ago? Before what clock is this time measured? Will other galaxies moving away from our galaxy at a speed higher than the speed of light also measure the same time?
albentezo,
Speaking of black holes, when two black holes collide, what actually collides?
to Albenzo
OK. I respect your opinion.
Shabbat Shalom
Yehuda
definitely not. I don't think there is a problem with the existence of dark matter. I think there is a challenge. that the work is not yet complete and that the level of reliability is not yet up to the same standard as the existence of the electron or the proton, but every scientific theory - every single one that has ever been practiced - has gone through a process from its pronunciation to its acceptance. The dark matter theory is still a work in progress but for now it successfully meets scientific standards and it seems (although we still don't know for sure) that it will pass it successfully.
The Higgs boson also took 40 years to find. In the meantime, was there a "problem" in the standard model of the particles? No, the work is simply not done yet. Only recently have we been able to measure gravitational waves, more than a century after their existence was predicted. Was the theory of relativity "problematic" during these hundred years? No. A problem with a theory is an internal contradiction, a contradiction with observed data, or simply a lack of evidence for its correctness. The theory of dark matter does not include internal contradictions, does not contradict observed data (just the opposite, it is the only one that fits all the data) and there is a good amount of evidence for its correctness. The collection of evidence is not yet such as to rule out the possibility of an alternative explanation, but it is impressive and growing every day. The search for dark matter particles did not last that long (it is important to remember that they did not start looking for it from the day the idea was uttered, nor did the appropriate technology suddenly appear at the same time as the idea), and if we were to apply the principle of "it takes a long time then there is no point, it must be wrong" Then half of the achievements of modern physics would go to waste.
Albanzo
Is it possible to draw the conclusion that we both think there is a problem with the existence of dark matter only that from this you conclude that it still exists because it has many reasons to be true, and I conclude that it apparently does not exist? Would you agree to that? Because if not then I don't know what to conclude.
Good day Albanzo
Yehuda
Miracles, Albanzo
Yehuda arrived 18 years ago on Earth.. He arrived from a parallel location. There the rules are different. He still hasn't gotten used to being on Earth. So forgive him..
Yehuda,
We have already talked dozens of times about the fact that I am not trying to convince anyone of the existence of dark matter. I am not a blind supporter of the theory and do not "give great confidence" to their existence as you claim. You say I hardly doubt, even though I have made it clear many times in the past that I certainly do. Even here, a few comments ago, I explained to Raphael that dark matter particles have not been detected microscopically and therefore their existence is by no means a settled fact. Do you even read what I write? It seems not.
I have told you many times that I have colleagues who are also trying to find alternative theories to gravity that do not include dark matter, and that I fully respect their research and efforts. What I've been trying to explain to you for years is that there is a right way to do it (look at all the data and look for an alternative theory that fits them) and there is a wrong way to do it (ignore everything that doesn't suit you, accuse people of fabricating data, rely on materials that don't reflect physical reality but intended for high school students, to maintain double standards and refuse to read evidence or testimonies because they are above your level).
Yehuda
We have not yet found the chemical process that explains how life began. Decades of searching…… so maybe your particles are the explanation?
How about some answer to what I asked you?
Albanzo
I am surprised by the great confidence you give to the existence of dark matter and energy, and do not doubt them (almost), despite decades in which their particle structure has not been revealed. But maybe you're right and I'm just insisting.
Good day Albanzo and thank you for your patience.
Yehuda.
Miracles
The laws of nature were invented and tested as you know only in our solar system by Homo sapiens found there. It is allowed to use them even in places where they have not been tested, but with great care and doubt. As soon as there is a discrepancy between the formula and the measurements we make in the field, it is ridiculous that we change the measurements by all kinds of strange additions such as dark matter and dark energy. You need to understand that although the formulas we created seem very stable and absolute, there are actually an infinite number of other formulas that will give the same measurable result within the uncertainty that always exists in measurements. Out of all the infinite results, we conveniently choose the simplest one to deal with (according to Ockham's Razor), but it absolutely does not have to be the correct one and it is possible that if we measure to greater distances we will have to choose another one from among the infinite others and the formula will take a slightly different form.
So, I'm not "dismissing science" in faraway places, but I'm just being cautious.
Details on my website article 20, 25 on this topic.
I do not think that an elastic collision cannot create gravitation and I have already said that I am organizing an experiment to prove it. Until then there is no point in arguing about it. If only plastic collision will explain the pushing gravity, then there will be a problem that the bodies will go and "fat" because of the plastic collision and this will require in some way to put them on a "diet" (or, of course, to accept your opinion, and give up the idea of pushing gravity.)
The design of the experiment is progressing.
Good Day
Sabdarmish Yehuda
http://yekumpashut.freevar.com/
Raphael,
The indirect evidence I'm talking about are indeed things that can be measured by physical means, simply indirectly. You can of course believe whatever you think is true, but this discussion has nothing to do with what can be physically measured and what can't. All the evidence within science are things that can be measured by physical means, some directly and some indirectly.
Yehuda,
You pour a lot of words and ignore the basic thing. You didn't answer any of the questions I asked you, you just evaded with an answer like "I don't agree, like that".
If you yourself admit that dark matter has a multitude of consequences in a multitude of subjects, and therefore there are a multitude of ways in which the theory can be tested, how can you claim that it is not nonsense to ignore all this spoils and refer to only one thing because that's what you want? Let's look at an example. Quantum mechanics was born when Planck tried to find a way to explain the energy density per unit frequency in the radiation spectrum of a black body. If someone comes to the site tomorrow and says, "Quantum mechanics is a mistake, there is no such thing. The black body problem can be solved by manually changing the power in the spectrum" (by the way, this is true). The man completely ignores all the other things that quantum mechanics explains, all its implications, Bell's experiments, the two-slit experiment, the duality of light, all the hundred or so years of research that support the theory. He deliberately ignores all this, looks only at the black body problem, and says that he has another way to solve it and therefore quantum mechanics is wrong. Is it nonsense or not nonsense?
If your answer is that it is nonsense, then you must understand that this is exactly what you are doing - choosing one aspect of a theory, ignoring the rest of the aspects (simply because they do not suit you), and from this aspect creating a false representation that the theory is wrong or unnecessary. If your answer is that the man in the quantum mechanics example is not talking nonsense, then I think we can end the discussion here and there is no need to add a word.
to Albenzo
You write that I say dark matter exists only to preserve Newton's gravitation formula. I don't think so. And the word "only" should be deleted. There are certainly other reasons such as for example that he helps in building large structures of the universe or that he helped during the Big Bang. Well I don't understand it, and you probably understand it more than I do. But when discussing dark matter, the conservation of Newton's gravitation formula determined by the rotation of the galaxies and its amount in galaxies and galaxy clusters is mainly determined by Newton's gravitation formula and it is clear to me how much and why. And I protest. And I do not accept your words that it is nonsense. I claim and will repeat and claim that Newton's formula was only proven for a distance of less than one light year and to deduce from it for a distance of millions and billions of light years this "nonsense" is not acceptable to me, mainly because this requires a huge amount of dark matter with strange properties of transparency, lack of friction and building on particles They have been looking for them for decades without much success. Even if you prove to me that it is "terrible" it helped in the big bang or in other cases. So maybe you're right and that would be a breaking point, but I don't understand it and I won't respond. So thank you for your learned answer but we remain divided.
Please respond gently
Yehuda
Raphael
That's not what Albenzo said, and you know it…
albenza,
I just wanted to find out for sure. I have no problem with indirect evidence for the existence of a thing.
I'm not one of those who only believe in things that can be measured with physical devices 🙂
Raphael,
This is indirect evidence. If we ignore for a moment what Nissim said and simplify to direct and indirect evidence, then there is still no direct evidence - no one has yet created a particle of dark matter in a laboratory, and as explained in the article, there are still differing opinions regarding exactly what the particles that make it up are. This is why there are still physicists who are looking for other solutions to problems, which do not include dark matter (but are not looking for solutions that do not include electromagnetism, for example).
The existence of dark matter is in the scientific consensus, but no one claims that it is a settled fact and that its existence should not be challenged or alternative solutions sought precisely because it has not even been observed microscopically yet. But what I have been trying to explain to Yehuda for several years now is that such alternative solutions would require a fundamental change of all our theories of gravity, which most physicists think is unlikely (because they are very good) and even those who think it is likely have been failing to do so for many years (no one He has not yet come close to formulating an alternative theory of gravity that scrapes the ankles of general relativity in its adaptation to observations and experiments). There is nothing wrong with looking for solutions that do not include dark matter, but it has to be done correctly - not by selectively choosing what is treated and what is not, not by ignoring everything that does not fit, and not by conspiracy theories.
Yehuda
The theory of relativity claims that gravity distorts space. Two phenomena that this Torah predicts are the bending of light and the slowing down of time. Two phenomena that were indeed observed.
Your Torah does not predict these phenomena. On the other hand - your Torah predicts that a rotating body will encounter drag and even change its trajectory in space. She also predicts that bodies will become very hot. It also predicts a eddy flow of the particles, doesn't it?
I don't think there are observations for the phenomena you observe.
Raphael
There is a serious problem with the concept of "direct evidence". Is the fact that Galileo saw 4 moons orbiting Jupiter evidence that there is gravity there? Yehuda will tell you no.
Is the fact that every night Galileo saw the 4 moons at other points around Jupiter evidence that the moons orbit Jupiter?
Are even the points that Galileo saw moons? A common response to Galileo's claims in his article "Siderius Nuncius" is that what Galileo saw were distortions in his telescope.
In general - philosophers will tell you that all evidence is not direct. Descartes is of course in their mind.
albenza,
You write that there is a very large amount of observational evidence and evidence for the existence of dark matter. Is it direct or indirect evidence? And if it is direct evidence, why are they still trying to discover it using special detectors (and not succeeding).
And just out of interest, I went to the entry of dark matter in the Hebrew Wikipedia. Of course, it also says that dark matter is the solution to several problems in physics, and not just one. There are roughly two examples of such problems - the problem of the missing mass in galaxies and the problem of creating structures. So even according to this source, there is no debate that dark matter is a phenomenon that is necessary to solve a variety of problems, and evidence for its existence comes from a variety of sources, and that it is ridiculous and completely dishonest to pick just one point from the fabric and completely ignore all the others.
First of all, it really doesn't matter (to me or anyone else) what is written on the Hebrew Wikipedia. This is just one source among thousands of sources, and not just any source, but one of the worst sources out there. But it really doesn't matter, because you agree that theoretically dark matter has many more roles and importance in physics, and if you agreed to read one of the many articles I sent you over the years, you would also know that there is a very large amount of observational evidence and evidence for its existence. So please explain two things to me:
1. If you know that dark matter has a lot of important implications for physics, why do you always write that it is only due to the stubbornness of physicists not to get rid of Newton's formula of gravity? Why don't you ever write that even if we forget about the formula, there will still be plenty of evidence for its existence and there will still be plenty of problems in physics that have no other solution than the dark matter solution that wears them like a glove? You are misrepresenting in your claim that if we were to change Newton's formula, there would be no need for dark matter, which is simply false. Not only would changing the formula completely contradict everything we know about gravity (as explained to you at length last month) but also this is only a drop in the sea of reasons to believe in the existence of dark matter.
2. If there are many roles for dark matter, why did you specifically choose the orbits as one role to address? You admit that you ignore the other implications of dark matter. Why not ignore the problem of orbits and concentrate on dark matter as a solution to the problem of the temperature spectrum of the background radiation? Of course this is a rhetorical question - your choice of what to ignore and what to address is arbitrarily based on the result you want to achieve. You have already decided what is true and what is not and now you choose in your heart what to consider and what to ignore in order to produce the distorted image that best fits what you want to be true.
to Albenzo
Dark matter may have many roles, but it comes to solve the huge lack of mass in spiral galaxies, elliptical galaxies, and in galaxy clusters, if you want to preserve Newton's formula or the general theory of relativity that deals with gravity. This explanation seems nonsense to you. Quote: - "Your (Yehuda's) absurd mantra that "dark matter exists only to preserve Newton's gravitation formula" (which I (Albanzo) personally have already explained to you dozens of times why this is nonsense)." End quote. So dear Albanzo, maybe in the English writings it is different, but in the Hebrew Wikipedia they really, really explained the need for the dark matter as I - Yehuda, explains. So we disagree. I am willing to agree that dark matter has another role in building the vast structures in the universe. Unfortunately, I am not well versed in this subject, but this does not rule out the importance of dark matter in galaxies of all kinds.
for miracles
You brought me Newton's law of persistence so that I could explain it to you again. You touched my heart. I will answer your question again:- "The reason we invent "laws of nature"? I will do so in my next response
Yehuda
Newton also has perseverance...
Miracles
Sorry you didn't understand and I don't feel like explaining again. Let us decide to differ. And regarding the theory of attribution I will respond when I study the subject.
good evening
Yehuda
Yehuda
You dismiss science by repeatedly claiming that we have no way of knowing what happens in distant places, or in distant times. This is *exactly* why we invent "laws of nature".
Your explanation of gravitational mass is based on persistence mass. You ignore the fact (to my understanding a fact) that elastic collisions cannot produce a gravity-like force, and ignore the fact that plastic collisions are supposed to produce warming.
You ignore observations like the slowing down of time and the bending of light.
Why?
Thanks
1. Do you know how to explain? up to a certain level. There are mathematical models that predict exactly such behavior. Theoretically there is no problem to build such a model, but as of today our ability to test them is not optimal. You must have heard that inflation theory (such a model) is very popular among theorists and is indeed supported by a lot of indirect evidence, but there is still no "smoking gun" for it. Cosmology in a period that is very close to the big bang is a very interesting field that has a lot of research (both observations and theories) but it is a difficult field that we still have to learn about.
2. Dark energy can be thought of in terms of the density of energy in a vacuum. That is, the energy that an empty space contains by virtue of being space, and not by the very things that exist within it. In the standard models this density is constant (also called cosmological constant). It is not customary to actually talk about the amount of dark energy because if its density is constant and space is infinite - then its amount is infinite. In any case, the quantity is not an interesting quantity because it is not a local quantity (for that matter, I currently care about how much dark energy there is around me and not how much there is in Pluto, so I will be interested in the energy density and not the total energy in space).
3. Dark energy is a property of space and is therefore everywhere, including black holes. But as I said earlier, in the current era its influence is very small (it produces a weak repulsive force) and therefore does not play a significant role in the creation processes of black holes. In the early universe the picture was different.
Albanzo thanks for the answer.
Do we know how to explain why at the beginning of the universe the force of repulsion was great and now it is small but in the process of growing?
Does this mean that the amount of dark energy in the universe changes with time?
Is it assumed that blacks also contain dark energy that "fights" gravity?
Yehuda,
Maybe if for once you would study the evidence and evidence for the existence of dark matter (or dark energy) instead of repeating over and over again your absurd mantra that "dark matter exists only to preserve Newton's gravitation formula" (which I personally have already explained to you dozens of times why it's nonsense), so you shouldn't have "believed" in this or that.
Raphael,
The simple answer is this: if you take two particles and put them next to each other, they will attract each other. At first slowly, then faster as the distance between them decreases, until they meet each other and collapse into a black hole. But, if you take two particles and in addition to the gravity that pulls them together you add an additional force that pushes them in opposite directions, it is possible that they will not collapse into a black hole (depending on the strength ratio of the attraction and repulsion forces). The expansion of the universe is just such a force, which pushes all bodies away from each other. Its force of rejection is not constant. Today it is very, very small but has grown over time. Once, close to the Big Bang, it was very big. To see exactly why the whole universe will not collapse into a black hole in the big bang model you have to look at the equations, but this is the principle in two words.
Nissim and Raphael
The universe expands only about 20 km per second per million light years, which is about 70 km per second per megafarsec. The expansion of the universe and the accelerated one can only be done if there is energy in the expanses of the universe that accelerates it and that is the dark energy. I believe in it just like I "believe" in dark matter.
And for miracles
You sometimes find things and draw conclusions that I didn't say
Where did you see that I conclude that all science is wrong??, there are parts of science that I think are inaccurate such as dark matter, dark energy, singular points and more, but that is not all science.
How did you infer from the fact that I said "tremendous masses" that there is no mass?, I don't understand.
And regarding your question about mass and gravity, I am currently studying the subject in connection with relativity and am not currently preparing to answer that. Please do not demand.
Bye, I'll be back in the evening
Until then please respond gently
Thanks
Yehuda
If at small distances gravity overcomes expansion then why did the universe expand when it was very small (like a black hole)?
Raphael
The universe does not expand at a certain "speed", but at a speed per unit distance. This is the "Hubble constant", and its value is approximately 160 km per second per million light years. You are right that this rate increases, and you are also right that at large distances the speed is higher than the speed of light.
But - at small distances gravity overcomes the expansion. Even the Andromeda galaxy, 2 million light years away, is approaching us, and one day it will collide with us. A black hole is much smaller than that, so the expansion of space has a negligible effect.
I'm qualifying this answer because I don't understand what dark energy is at all…. But by and large I think what I wrote is convincing.... 🙂
Yehuda
I was talking about a time span of much less than 1 millionth millionth millionth millionth millionth millionth of a second, and you are talking about distances of tens and hundreds of thousands of light years. Do you understand? We don't talk in the same units at all 🙂
No one claims that the laws of nature were as they are today at the time of the big bang, or at the center of a black hole. Do you conclude that all science is wrong?
You talk about "huge masses", but if I understand what you are saying, you claim that there is no such thing as a "mass".
Here's another question you won't answer - does your model have both gravity and persistence? Newton has two meanings for mass, do you also?
Miracles
I understood that even today the universe is expanding at a speed that exceeds the speed of light and not only that, but that the speed is accelerating all the time. And all this because of dark energy. So the question arises - assuming that black holes also have dark energy in the same ratio as in the universe, then why don't black holes spread?
In short, I want to understand what is the fundamental difference between a black hole and the universe at its beginning, and I mean the point where *all* the laws of physics known to us (including gravity) began to operate, which according to my understanding happened less than a second after the big bang.
Miracles
Started from the sipa of your previous comment. What you wrote:- "Assuming there was gravity at this point" end quote. is the most important thing I read from you! To understand that relying on the laws of physics known to us from the yard closest to us in the solar system, in the vast reaches of the cosmos, or in the conditions of enormous masses or in the conditions of the big bang. This is something that cannot be done with confidence. It is appropriate that this paragraph of yours should appear in every response of a common scientist (and I am not disrespecting, God forbid), therefore, relying on the gravitation formula at the enormous distances of the galaxies and from this to conclude the "glorious creation - the dark matter" is something that will not be done, and you said that miracles, unless you deny to that now.
Therefore the dark mass explanation for any gravitational problem has its origin in doubt.
And in the same style I will answer your second response/question: - "What do you mean by dampers?"
The answer:- I really don't know how my gravitationally pushing particles will behave near bodies of enormous mass, and no one does! Is the collision elastic?, or maybe plastic?, or maybe both?
And although no one can know, I only guess that in this situation or close to it the maximum gravitation per unit of mass will be obtained.
Is it a black hole?, what do you say miracles in light of your previous answer, and assuming that gravitational pushing exists?? Your answer will be no less good than mine in the great uncertainty that exists here.
Good day miracles!
Please respond gently
Yehuda
Raphael
At the beginning of the Big Bang, and to this day, space itself is inflating. At first, the rate of inflation was far beyond the speed of light so there was no time for matter to collapse in on itself.
This is of course assuming there was gravity at this point.
Yehuda
What do you mean shock absorbers? Are they swallowed by the body, or is there an elastic collision?
To Raphael
Perhaps the conclusion should really be that the primordial universe was not centered in one singular point. In general, the laws of physics are not necessarily defined in the extreme conditions of 13.8 billion years ago as they are today, and all conclusions are with many question marks.
Please respond gently
Yehuda
I have a question, the answer to which may be very trivial.
If all the matter of the universe was compressed at a certain time (less than a second after the big bang) in such a small place - then how did this place expand and not immediately shrink again to a singular point like we see black holes?
Of course I understand that the difference between a compressed universe and a black hole is black black is inside the universe while the universe is inside something that is not scientifically defined and can never be scientifically defined.
Miracles and Israel
Regarding black holes, there are bodies in Pushing Gravity that are so dense that they absorb all the particles that hit them, which means that the gravity they create is the greatest possible according to Pushing Gravity. Is it a black hole?? Not sure. The black hole by its very definition absorbs even the radiation of light. I'm not sure that the gravity will be sufficient according to the pushing gravity to slow down the light as well.
Good Day
Yehuda
Yoda
There is no problem with black holes in pushing, and Reuven Nir explains this in the book "Attraction". What simple bodies have a high density that stops all the particles.
Joshua
How do you explain the attraction of the earth to the moon?
Yehuda
I ask a very specific question - are there possible black holes in your model? In my understanding, the answer is no.
Miracles
Joshua is a poor man. I proved several months ago that he only responds to the name Sabdarmish Yehuda and that turns him on. He is unable to understand science and he "shoots" in all directions. Arguing with him is useless and don't try to understand him because it won't help. He accuses me of mental fixation?, of senility, being a board head and a few other things but I assure you that he is not at all familiar with what I say or write. The mental fixation is with him, so leave him alone.
Let us narrow down to the article and what is written in it. I do not agree to write in it even though it was written by the best scientists. It could be that blacks are the dark matter, but they have already checked this and apparently it is not true. We should have seen gravitational disturbances most often in astronomical observations. Unfortunately, these wastes do not exist to the required extent.
And regarding black holes, I believe in bodies with a huge mass that will do gravitational dust according to the theory of relativity. They do not have to be black holes, contamination is also done by bodies that are not black holes such as the sun.
Please respond gently
Yehuda
Joshua
I find it hard to argue with what you say…. Judah, help me?
Miracles
I'm not disrespecting. I analyze Yehuda's reactions. You explain to him all the time and it doesn't help, others also explain where he is wrong and it doesn't help. What should you understand from this? A mental fixation that leads him to some sort of grandeur complex. Everyone is wrong, only he is right. More than once you have pointed out to him that mathematical knowledge at the high school level is not enough and he ignores it. Apparently he has stepped into shoes that are several sizes bigger than him and he is drowning in his mental fixation without being aware of it.
Yehuda
1. What does faith have to do with science?
2. Why do you ignore guys in your theory? It does not explain changes over time. She doesn't explain gravity (and you don't understand why at all). It does not explain the bending of light. It rejects general relativity.
I'll ask you again - is the idea of a black hole ridiculous in your eyes?
for miracles
A theory is ridiculous if it tries, for example, in seemingly scientific ways to prove scientific correctness. The article deals with dark matter and shows a way in which its existence is proven. Regardless of my known opinion on dark matter, I show that the way to prove the existence of dark matter with bodies that do not yet exist is refutable. My theory accepts the existence of very large bodies in terms of valve, but the gravitation they create will not be a prop for the mass but for the cross section of the mass. In addition, it does not accept singular points of any kind or infinite gravitation of bodies.
But why are you drawn to my theory? Concentrate on what is written in the article. Do you believe that somewhere in the cosmos there are black holes that make up the dark mass? Good for you, but don't you think you are ahead of the curve? First you will find the black holes and then you will decide why they are good.
And as for poor Joshua, I have nothing to add. Wretches like him usually don't identify.
Good Day
Please respond gently
Yehuda
Joshua
Belittling someone's opinions will not make them change their opinions. It is better to try to show him why, in your opinion, he is wrong.
Miracles
Judah cannot be aware. He lost this ability. He suffered from chronic fixation syndrome.
Yehuda
Why do you consistently ignore basic questions about your theory?
And here's another question - are you aware that your theory prevents the existence of black holes?
Yehuda
To me, a theory is debunked if it contradicts the observations, or there is no way to test its correctness. Is your opinion different from mine?
And in particular - is the existence of a black hole ridiculous in your eyes?
Joshua
Aren't you the wretch who responded to Professor Avi Lev's words in an insulting way just because you thought it was Yehuda??, haven't you learned yet that Yehuda is not worth messing with? People like you have no place on the science site?
Yehoshua, you are a poor man who is not worth a response!
Yehuda
Please respond gently
Yehuda
Your rudeness crosses the line of good taste. They explain and explain to you and you forcefully insist on nonsense. I'm sorry for you Yehuda, but you already show signs of senility. In the street language it is called Rosh Kresh. Nissim is right
hot or nice
The speed of the waves is written explicitly in the current article.
for miracles
I show you a ridiculous solution, and prove to you the ridiculousness of it, and from that you conclude that this is my opinion on all the solutions I don't agree with??
I'm sorry if that's your rebuttable conclusion.
Good Day
Yehuda
hot or nice
Gravitational force waves travel at the same speed as electromagnetic force waves - the speed of light.
Yehuda
You're right. Any solution that is not your solution is ridiculous.
very mature
Miracles
Things are proven with what is, not with what is not. It seems ridiculous to me that with "there are no black holes" they are trying to prove the "there is no dark matter"
But don't want to get into an argument, if you think it's not ridiculous then so be it
Yehuda
Yehuda
So you don't notice it….
Someone with a Doctor of Physics education in the field of cosmology, with many years of experience in the field, publishes a scientific article that has undergone tough peer review, an article that you are unable to understand (and neither am I, unfortunately).
And you are the one who sees it as ridiculous.
Yehuda, I don't think it's necessary to point out that what's ridiculous here is...
Miracles
I'm not mocking, but sometimes I want to show the ridiculousness in the words of this or that scientist.
Let us accept my words with a smile and respond gently.
I'm interested in how fast gravity waves move. Can something enlighten my eyes? They are not moving in space-time but a distortion of space-time itself, so do they move at a speed lower than light or....?
Yehuda
You mock any scientist who thinks differently than you.
Did you notice that?
Miracles
Is there evidence for black holes?, maybe, but it's a little funny to me that additional black holes that have not yet been discovered form the basis of new evidence for dark matter that has not yet been discovered. just funny
And as the trackers say:- The world is funny so I laugh!
And regarding "my" particles I will not comment for the time being until Minkowski space and matrices are clearer to me.
So good morning Nissim, and have a good week everyone
Yehuda
Yehuda
My grandson, a 10-year-old boy, is a gifted child and is active in classes for youth seeking science. He is willing to give you astronomy lessons for free.
Yehuda
You will surely agree that there is more evidence for black holes than for your particles.
Beyond that, behind black holes there is an excellent theory, which itself has a lot of evidence, evidence that your theory cannot explain at all. You have to agree to that too.
To be clear - "must agree" means you have no rational reason not to agree.
What a beauty!. Black holes that no one can see, will explain the dark matter that no one can see, really, really, blind science and all this to preserve a formula that has barely been proven in the solar system.
And besides, for anyone interested in my gravity studies, I'm currently confronting the four-dimensional explanation of Minkowski space. All the best, and have a good week!
Please respond gently
Yehuda