Surprisingly, it was recently discovered that dark matter is absent from the inner regions of some galaxies, especially those larger than our Milky Way galaxy, and especially in the early universe of about ten billion years ago
One of the central insights of cosmology, which was formulated on the basis of many and varied astronomical observations, is that most of the matter in the universe is "dark matter". This material does not emit any light and therefore cannot be directly observed in telescopes, but it is measured through the high speeds of the luminous bodies, which are caused by the gravitational force that the dark matter exerts on them. The exact nature of the dark matter particles is not yet known, and intensive research is being done in laboratories and particle accelerators in the hope of identifying them.
Surprisingly, it was recently discovered that dark matter is absent from the inner regions of some galaxies, especially those larger than our Milky Way galaxy, and especially in the early universe about ten billion years ago. The "missing mass problem" became the "missing dark matter mystery". Using the large European telescope in Chile, and with the help of advanced adaptive optics techniques, astronomers measured rotation speeds of hydrogen gas around massive galaxies in the early universe, and learned that about a third of them lacked dark matter. Is this discovery supposed to undermine confidence in the existence of dark matter? Or does it indicate his unexpected qualities?
Prof. Avishai Dekel and his colleagues from the Rakah Institute at the Hebrew University provide for the first time an explanation for the mystery, in a scientific article published in the journal of the Royal Astronomical Society, within the standard cosmological model of dark matter. The explanation combines two known physical processes that link the dark matter and the normal luminous matter through the force of gravity, processes that cause the dark matter to be pushed out of the luminous galaxy.
The proposed scenario is two-stage. In the first stage, small galaxies, which move around and towards the center of the large galaxy in question, "heat" the dark matter in it, that is, increase the random movement speeds of the dark matter particles. This happens through a well-known process of "dynamic friction", which originates from the force of gravity. The velocities of the particles, now approaching the "escape velocity" from the galaxy, make the dark matter more sensitive to being pushed from the inner regions to the outside of the galaxy. In the second stage, winds emitted strongly from the surroundings of the giant black hole at the center of the galaxy blow gas (mostly hydrogen) from the central region. This weakens the gravitational force acting on the dark matter toward the center, and it responds by spreading out from the center to the outer edges of the galaxy. This creates a central region that has no dark matter, as the observations show. The stars remain in this region because they were initially high density in the center, bound more strongly to the center of the galaxy by gravity.
"The proposed scenario explains why the missing dark matter phenomenon occurs mainly in massive galaxies and at early times," says Prof. Dekel, "We know from previous studies that only in such massive galaxies, and only in the distant past when the universe was much denser, the small galaxies colliding with the dark matter were compact enough for the purpose of heating the dark matter. Also, only in such massive galaxies, and at early times, did the giant black holes at their centers absorb matter into them at a fast enough rate, producing powerful winds from some of it before it was swallowed up by the black hole itself.'
Prof. Dekel adds and points out that there is now surprising new observational evidence of a lack of dark matter even in a small part of the dwarf galaxies. "This challenges us to propose a similar scenario, with the necessary changes, which could possibly be responsible for pushing the dark matter out of dwarf galaxies as well," he concludes.
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Hello dear Israel Shapira!
how are you these days
I am very interested in communicating with you directly and not only through science.
I would appreciate it if you could contact me at the following email:
sevdeleon@gmail.com
waiting for your reply.
All the best
Sabdarmish Yehuda
Israel my friend
The pushing also works on the pushing particles themselves and they move to a certain extent around the sun just like the planets just like leaves fly in the wind without feeling almost any friction. Therefore, the friction that Feynman discovered will only be felt when the movement is not in the direction of the general movement of the planets, for example in the Pioneer anomaly, the movement is perpendicular to the orbits of the planets and therefore a certain friction is felt.
Regarding the elastic collisions I have a disagreement with our friend Nisim. I went to the Weizmann Institute and they agreed to do an experiment which unfortunately did not produce clear results.
Good Day
Sabdarmish Yehuda
Yehuda
Until you find an adequate solution to Feynman friction and elastic collisions, it will be extremely difficult to accept pushing as an explanation for gravity.
There is still no response from my father regarding recent comments. So count the commenters or ignore?
Dear Israel Shapira!, A voice from the past,
How are you??
I am happy that the voices opposing dark matter are getting stronger and the day is not far when it will pass from the world.
And as for my solution to dark matter it is not necessarily related to my simple universe. What I did is a simple thing, I looked for all the possibilities for a solution with a certain method that does not neglect any possibility for a solution. I came up with 20 possibilities, and it is clear that most of them are not correct, and then I checked them all by elimination, and I was left with two possible solutions:- the well-known solution of gravitation with the dark matter, and a solution of the pressure differences that I think exists in the space of the universe and does not require gravitation at all and of course does not need to dark matter and energy. Obviously I prefer this simple solution.
Everyone can own the solution they prefer.
All the best
And please respond gently
Sabdarmish Yehuda
Yehuda ach Salno.
For years you have been fighting your (righteous! 🙂 ) war on dark matter.
But your alternative - the simple universe - also suffers from difficulties that do not fall from the difficulties of dark matter.
Regarding my father - his honor rests in his place and his work is blessed. But sometimes I also feel that he doesn't completely count the commenters. Several times I asked him about recent comments and I didn't answer. So let's see if he will address the issue now or continue to ignore it.
to the anonymous user
You obviously don't know my father at all. He loves science and loves the science site and it is true that it is a job without adequate compensation and only an Aram with a love for science can last in it. Be strong and brave, my father!
Sabdarmish Yehuda
To the anonymous commenter who writes that "My father has long been indifferent to commenters, he doesn't seem to care about them or the site." You, what is wrong and you apparently do not know Avi Blizovsky at all!. Years of conversations with my father only bring me to the opposite conclusion. My father loves science and he cares a lot about what we think about the site. Thank you Avi Blizovsky
Yehuda
My father has not treated the commenters for a long time, he doesn't seem to care about them or the site.
One thing is agreed and clear: the galaxies do not move at the speed dictated to them by the gravitation formula and/or the amount of visible-baryonic matter present in the galaxy. Therefore, the solution to the problem can be one of two options: either change the amount of matter in the galaxy with the help of additional matter that appears somewhere in the galaxy or leave the amount of matter but slightly change the formula.
The solution of additional matter explains another phenomenon of contamination in the galaxy but it requires giving the additional matter strange properties such as the lack of friction and also being dark and invisible.
I think a different or different formula should be tried.
Sabdarmish Yehuda
One can try to explain phenomena by assuming the existence of hypothetical particles. This was done with the netrins and even with the well-remembered omega-minus Professor Yuval Neman, and with the well-known Higgs boson. And several years must be allowed to discover them. But in the case of the dark matter particles the situation will continue from the beginning of the twentieth century and without much success. Science must take into account the possibility of the non-existence of these dark matter particles, with all that follows.
My dear father
The last three commenters really deny the existence of dark matter like me, why don't you approve of publishing my response? It's really sad to think, God forbid, that the science website is taking steps of scientific censorship?, sad.
The dark matter is "absent" from galaxies - because the theory is simply wrong!! No one will admit it, and cosmologists will continue to come up with imaginary theories that no one can prove (and therefore cannot disprove). The 'scientists' will continue their musings, and it doesn't matter to anyone anyway...
Dark matter hasn't been proven yet and they already say it doesn't exist?
Towers are being built on a foundation that does not yet exist
Maybe this is part of the properties of dark matter? Not much is known about him.
Maybe this is a sign that the explanation for the 2 phenomena is different and not necessarily dark matter?
Maybe we start by disproving or confirming its existence before running to build a theory on top of the theory of dark matter?
I am not a physicist, astronomer or scientist. I am an avid reader of discoveries and research in the field of space exploration. Decades of research and thousands of theories brings us to the conclusion that the more we discover, the less we understand. We may never understand. Every day we are informed of discoveries that actually contradict what we thought.
I don't like it, but you are completely confused with the big bang hypothesis
After all, we have to keep it existing, otherwise all the research falls into disrepair
All basic explanation falls away
As Professor Avishai discussed in his lecture on the formation of the universe
Brings three or two basic conditions according to which the theory is established
Even if one of them does not exist, the theory is not true
And suddenly we see that there is no uniformity in the universe
So how should he stabilize the theory
So we formulate some kind of solution
which contradicts the basis on which the theory exists
You don't believe me, he is contradicting himself
So write on YouTube
Avishai Dekel the Big Bang
Come to his lecture
Dear Avi Blizovsky!
Please confirm my last response to this article.
Thanks
Sabdarmish Yehuda
The beginning of the article can also be read differently:
One of the central insights of cosmology, which was formulated on the basis of many and varied astronomical observations, is
Most of the matter in the universe is "dark matter".
should be written:
Most of the universe does not follow the known gravity formulas!
An attempt to explain in the rest of the title the tremendous rotational movement of spiral galaxies with the help of a magical, vile and illusory substance (the dark matter) is unscientific and goes against Popper's requirement that it be possible to put the claim to the test of refutation experiments!, because (quote):
This material (the dark) does not emit any light and therefore cannot be directly observed in telescopes" (end of quote).
The unproven assertion that: (quote):
"The high speeds of the luminous bodies, which are caused by the gravitational force that the dark matter exerts on them" (end quote).
It is only one of the possibilities for explaining the high speed of the visible radioactive material, and there are 20 other possibilities, of which apparently only one is correct. Just for Dugmar, other possibilities that are no less good than dark matter are: the change of the gravitational constant G to the enormous distances of the universe, differences between gravitational mass and inertial mass under the conditions of large galaxies, the change of the gravitation formula to large distances, the change of Newton's second law at low accelerations (the "Mond" theory of Professor Milgrom), pressure differences in the universe, and much more. I counted 20 options and preferred one. There is no reason why a gravitation formula that correctly explains the movement of the solar system, which is a thousand light years in size, will be accurate in explaining the rapid movement of bodies, which are millions or trillions of times larger than the solar system. Just like donkeys (maybe) pull carts but big trains move differently.
The exact nature of the dark matter particles is not yet known, and it is a shame for the intensive research in laboratories and particle accelerators that is done in the hope of identifying them, but unfortunately, they do not exist.
Dark matter is the biggest scientific mistake of twentieth century scientists. Let us be brave and free ourselves from this mistake!!
Please respond gently,
Happy New Year to all science readers
Sabdarmish Yehuda
Wait - so how did similar massive galaxies, closer to us, get the dark matter back later???
The subject of dark matter is waiting for a serious breakthrough in new measurements or calculations - either they will see what it is or they will see that it does not exist. There is a long list of claims that it does not exist, and there is a long list of claims about its properties, but there is still no breakthrough.