(English version at the end)
De la matière noire: où ça? (No 19)
Si l'explication du professeur de physique Brian Cox est correcte, la mienne l'est également. Je soupçonnais l'existence d'un phénomène sans pouvoir le démontrer et le décrire. De toute évidence, ce phénomène est connu auprès de la communauté scientifique. Quel impact ce phénomène peut-il avoir sur notre compréhension du fonctionnement d'une galaxie?
Depuis des lunes, pour expliquer le fonctionnement des galaxies, on cherche une force autre que la gravité que l'on croit être une force trop faible. C'est ainsi qu'on parle de matière noire et d'énergie noire: noire parce qu'on ne parvient pas à l'identifier, à la mesurer et à la définir.
Un festival de théories
Et si cette matière noire alléguée n'existait pas? Les efforts à date pour la découvrir n'ont donné aucun résultat, des efforts qui dépassent l'entendement et mobilisent des énergies déconcertantes. Les expériences et les théories ne cessent de se multiplier à ce sujet surtout depuis qu'on constate que l'univers est en expansion et que la vitesse de cette expansion ne cesse d'augmenter. Cependant, dans la quasi-totalité des théories actuelles, la gravité ne fait pas partie de l'équation. Il faut admettre que, vu la taille des galaxies, on tend à imaginer une force drôlement plus puissante que la gravité pour expliquer leur fonctionnement.
Un cadre conceptuel général
Dans un récent documentaire publié par BBC Earth, le professeur Cox a soutenu que le fonctionnement d'une galaxie s'apparente avec celui d'un ouragan qu'on observe à partir de la Station spatiale internationale. Au centre de tout ouragan on retrouve une sorte de vide spatial dont la nature diffère du reste de l'ouragan. C'est une illusion d'optique de croire que ce centre retient le reste de la matière de l'ouragan. En fait, il s'agirait plutôt de l'inverse. Cet aspect de l'ouragan classique s'applique au fonctionnement d'une galaxie, selon le professeur Cox. Curieusement, je me sers de cette comparaison depuis quelques années déjà. Mais, la comparaison s'arrête là: une galaxie, ce n'est pas un ouragan!
Le professeur Cox, du même souffle, soutient que les lois de la physique ne peuvent être différentes à différents endroits de l'Univers: un autre concept que j'ai souligné dans des documents précédents. Ce qui explique un phénomène dans une région de l'Univers doit être également valable dans une autre région.
Nous savons que la formation des galaxies a débuté immédiatement après le Big Bang sous l'influence de la gravité. Pourquoi croit-on que la gravité est nettement insuffisante pour assurer le fonctionnement des galaxies si elle est responsable de leur formation? C'est comme prétendre qu'une autre force prend le relais de la gravité après un certain temps. Si on croit qu'il existe une force supérieure à la gravité, est-il possible que notre conception de la gravité soit déficiente? Est-il possible qu'on sous-estime la puissance de la gravité?
La rotation au centre d'une galaxie
Nous savons que le trou noir au centre d'une galaxie n'est pas passif ou inerte, mais plutôt en rotation. Cette rotation dépasse même la vitesse de la lumière. Donc, rien n'en sort. Aucune matière n'a pu être observée dans ce trou noir qui représente toujours 3% de la galaxie, nonobstant la taille de la galaxie. Intriguant, n'est-ce pas?
Or, si rien n'en sort parce que tout ce qui y entre est détruit, il va de soi qu'il n'y a aucune matière dans ce soi-disant trou noir. Qui dit absence de matière dit absence de gravité ou toute autre forme d'énergie, puisque la gravité est produite par la matière. Voilà la contradiction qui contamine les théories modernes destinées à expliquer le fonctionnement d'une galaxie. Un espace où rien n'existe serait responsable de retenir des milliards de planètes à plus de 100 000 années-lumière de diamètre. Trop, c'est comme pas assez!
L'erreur me semble due au fait que l'on croit que ce centre retient le reste de la galaxie, alors que je crois plutôt que ce centre est produit par le reste de la galaxie. Ceux qui croient qu'il existe au centre de toute galaxie une forme d'énergie d'une extrême puissance représentent la majorité, présentement. Ce raisonnement semble le plus logique: qui oserait prétendre l'inverse? Pourtant, cette explication me semble erronée. Les commentaires du Professeur Cox me laissent croire qu'il ne croit pas dans l'existence d'une matière noire au centre des galaxies.
Si, au centre d'une galaxie, il existait une force, une forme d'énergie d'une puissance telle qu'elle permettrait de retenir des étoiles et de planètes à 50 000 années-lumière plus loin, en moins de deux cette énergie avalerait la galaxie au complet: ce serait déjà fait depuis longtemps si c'était le cas, d'ailleurs. Comme l'existence des galaxies date du début de l'univers tel que nous le connaissons, il va de soi qu'il ne peut exister une telle énergie au centre d'une galaxie.
Le professeur Cox prétend que cette rotation au centre d'une galaxie est attribuable au principe physique suivant: la conservation du moment cinétique. La gravité entraîne une pression sur la matière qui, sous cet effet de contraction, pivote. Simplement dit, ce principe opère lorsque votre évier se vide de son eau. Cette notion particulière me semble suffire pour expliquer l'existence et le fonctionnement d'une galaxie. Eureka!
La gravité produit une pression sur la matière
Il y a une raison simple qui justifie la présence d'un trou noir au centre d'une galaxie et non ailleurs dans la galaxie: la pression est distribuée de manière uniforme de sorte qu'elle est maximale au centre et minimale à la périphérie. Plus on s'approche du centre, plus forte est la gravité. Autrement dit, la gravité augmente avec l'augmentation du nombre de corps célestes par unité d'espace.
Cependant, ça n'explique pas pourquoi il n'y a qu'un centre dans une galaxie. Ne serait-il pas plus réaliste de simplement soutenir qu'une galaxie se forme autour d'un trou noir puissant qui attire la matière de sa région. Cette conception exige qu'on assume qu'un trou noir précède la formation d'une galaxie, un préalable qui me semble irréaliste.
Note: Une année-lumière = 9 461 000 000 000 km
La gravité attire et repousse la matière: attraction-répulsion
En même temps que la gravité attire la matière de la galaxie vers un centre, une force contraire empêche l'effondrement de la galaxie sur elle-même. On observe un phénomène similaire pour toute étoile, notre Soleil par exemple. La gravité produit tellement de pression sur la matière de notre Soleil qu'il s'en dégage de l'énergie, de la chaleur. En même temps que cette contraction permet la formation de l'étoile, l'énergie qui en découle l'empêche de s'effondrer sur elle-même. Ce pourrait bien être ce qui se produit dans le cas d'une galaxie. Des recherches ont démontré que la gravité a la capacité de produire de la pression sur la matière, ce qui est nettement plus visible lorsqu'il s'agit de gaz. Cet aspect est crucial pour mon hypothèse: pas de pression pas d'hypothèse, j'en suis fort conscient...
La gravité: où ça?
La gravité existe partout où il y a de la matière. Il n'y a aucun endroit sans gravité, si minime soit-elle. Parce que cette gravité est peu perceptible dans une matière de petite taille, ça ne signifie pas qu'elle n'existe pas. À mesure que la taille d'un objet quelconque augmente, il y a une augmentation de la pression au centre de cet objet, ce qui entraîne plus une production de chaleur due à la friction. Encore faut-il qu'il y ait de la friction: une matière solide ne peut dégager de la chaleur.
Cette idée s'applique bien à un seul corps. Mais, qu'en est-il d'un ensemble de corps célestes, une galaxie par exemple? Qu'arrive-t-il lorsqu'il y a une accumulation de corps célestes dans un même voisinage, comme un million de planètes dans un espace de la taille de notre système solaire? Il semble que c'est ainsi que les galaxies se forment et qu'un trou noir apparaît au centre: c'est mon hypothèse. En accumulant de la matière dans un espace donné, le phénomène de conservation du moment angulaire surgit progressivement et se traduit par un effet de rotation.
Un doute légitime
Pourquoi cet effet de rotation n'a pas comme conséquence ultime d'avaler ou d'absorber tout ce qui s'en approche? Vous songez sûrement à l'image de votre évier qui se vide. La gravité à proximité du trou noir (endroit désigné comme l'horizon des événements) ne provient pas du trou noir, mais de la matière entourant le trou noir. La matière près du trou noir est retenue par le reste de tout ce qui compose la galaxie. Cette gravité répandue dans la galaxie me semble suffisante pour maintenir un équilibre et empêcher une absorption rapide vers le centre. Certes, toute galaxie finira par s'écraser sur elle-même lorsqu'elle sera davantage concentrée.
Ce qui est vrai pour une étoile me semble vrai pour une galaxie. Pourquoi pas? Une raison de plus pour continuer mon interrogation.....
Black matter: really?
If physics professor Brian Cox's explanation is correct, so is mine. I suspected a phenomenon but could not demonstrate and describe it. Obviously, this phenomenon is well known to the scientific community. What impact can this phenomenon have on our understanding of how a galaxy works?
For ages, to explain the functioning of galaxies, we have been looking for a force other than gravity, which we believe to be too weak. This is how we talk about dark matter and dark energy: dark because we cannot identify it, measure it nor define it.
A festival of theories
What if this alleged dark matter did not exist? Efforts to date to discover it have not yielded any results, efforts that are beyond comprehension and mobilize disconcerting energies. Experiments and theories continue to multiply on this subject, especially since it has been observed that the universe is expanding and that the speed of this expansion continues to increase. However, in almost all current theories, gravity is not part of the equation. We must admit that, given the size of galaxies, we tend to imagine a force much more powerful than gravity to explain their functioning.
A general conceptual framework
In a recent documentary published by BBC Earth, Professor Cox argued that the functioning of a galaxy is similar to that of a hurricane observed from the International Space Station. At the center of any hurricane there is a kind of vacuum in space that is different in nature from the rest of the hurricane. It is an optical illusion to believe that this center holds the rest of the hurricane's matter. In fact, the opposite is true. This aspect of the classic hurricane applies to the functioning of a galaxy. I have been using this comparison for some years now. But the comparison ends there: a galaxy is not a hurricane!
Professor Cox, in the same breath, maintains that the laws of physics cannot be different in different parts of the Universe: another concept that I have highlighted in previous papers. What explains a phenomenon in one region of the Universe must also be valid in another region.
We know that the formation of galaxies started immediately after the Big Bang under the influence of gravity. Why do we believe that gravity is clearly insufficient to ensure the functioning of galaxies if it is responsible for their formation? It is like claiming that another force takes over from gravity after a certain time. If we believe that there is a force greater than gravity, is it possible that our conception of gravity is deficient? Are we underestimating the power of gravity?
The rotation at the center of a galaxy
We know that the black hole at the center of a galaxy is not passive or inert, but rather in rotation. This rotation exceeds even the speed of light. Therefore, nothing comes out of it. No matter can be observed in this black hole which still represents 3% of the galaxy, notwithstanding the size of the galaxy. Intriguing, isn't it?
If nothing comes out of it because everything that goes in is destroyed, it goes without saying that there is no matter in this so-called black hole. The absence of matter means the absence of gravity or any other form of energy, since gravity is produced by matter. This is the contradiction that contaminates modern theories that try to explain the functioning of a galaxy. A space where nothing exists would be responsible for holding billions of planets more than 100,000 light-years across. Too much is like not enough!
The error seems to me to be that this center is believed to be holding back the rest of the galaxy, whereas I believe that this center is produced by the rest of the galaxy. Those who believe that there is some form of extremely powerful energy at the center of every galaxy are the majority at present. This reasoning seems the most logical, though: who would dare to claim the opposite? However, this explanation seems wrong to me.
If, at the center of a galaxy, there was a force, a form of energy of such power that it could hold back stars and planets 50,000 light-years away, this energy would swallow the entire galaxy in no time. Since the existence of galaxies dates back to the beginning of the universe as we know it, it goes without saying that such energy cannot exist at the center of a galaxy.
Gravity produces pressure on matter
There is a simple reason why there is a black hole at the center of a galaxy and not elsewhere in the galaxy: the pressure is uniformly distributed so that it is maximal at the center and minimal at the periphery. The closer to the center, the stronger the gravity. In other words, gravity increases with the increase of the number of celestial bodies per unit of space. However, this does not explain why there is only one center in a galaxy. Wouldn't it be more realistic to simply argue that a galaxy forms around a powerful black hole that attracts matter from its region? This view requires the assumption that a black hole precedes the formation of a galaxy, a prerequisite that seems unrealistic.
For ages, to explain the functioning of galaxies, we have been looking for a force other than gravity, which we believe to be too weak. This is how we talk about dark matter and dark energy: dark because we cannot identify it, measure it nor define it.
A festival of theories
What if this alleged dark matter did not exist? Efforts to date to discover it have not yielded any results, efforts that are beyond comprehension and mobilize disconcerting energies. Experiments and theories continue to multiply on this subject, especially since it has been observed that the universe is expanding and that the speed of this expansion continues to increase. However, in almost all current theories, gravity is not part of the equation. We must admit that, given the size of galaxies, we tend to imagine a force much more powerful than gravity to explain their functioning.
In a recent documentary published by BBC Earth, Professor Cox argued that the functioning of a galaxy is similar to that of a hurricane observed from the International Space Station. At the center of any hurricane there is a kind of vacuum in space that is different in nature from the rest of the hurricane. It is an optical illusion to believe that this center holds the rest of the hurricane's matter. In fact, the opposite is true. This aspect of the classic hurricane applies to the functioning of a galaxy. I have been using this comparison for some years now. But the comparison ends there: a galaxy is not a hurricane!
Professor Cox, in the same breath, maintains that the laws of physics cannot be different in different parts of the Universe: another concept that I have highlighted in previous papers. What explains a phenomenon in one region of the Universe must also be valid in another region.
We know that the formation of galaxies started immediately after the Big Bang under the influence of gravity. Why do we believe that gravity is clearly insufficient to ensure the functioning of galaxies if it is responsible for their formation? It is like claiming that another force takes over from gravity after a certain time. If we believe that there is a force greater than gravity, is it possible that our conception of gravity is deficient? Are we underestimating the power of gravity?
The rotation at the center of a galaxy
We know that the black hole at the center of a galaxy is not passive or inert, but rather in rotation. This rotation exceeds even the speed of light. Therefore, nothing comes out of it. No matter can be observed in this black hole which still represents 3% of the galaxy, notwithstanding the size of the galaxy. Intriguing, isn't it?
If nothing comes out of it because everything that goes in is destroyed, it goes without saying that there is no matter in this so-called black hole. The absence of matter means the absence of gravity or any other form of energy, since gravity is produced by matter. This is the contradiction that contaminates modern theories that try to explain the functioning of a galaxy. A space where nothing exists would be responsible for holding billions of planets more than 100,000 light-years across. Too much is like not enough!
The error seems to me to be that this center is believed to be holding back the rest of the galaxy, whereas I believe that this center is produced by the rest of the galaxy. Those who believe that there is some form of extremely powerful energy at the center of every galaxy are the majority at present. This reasoning seems the most logical, though: who would dare to claim the opposite? However, this explanation seems wrong to me.
If, at the center of a galaxy, there was a force, a form of energy of such power that it could hold back stars and planets 50,000 light-years away, this energy would swallow the entire galaxy in no time. Since the existence of galaxies dates back to the beginning of the universe as we know it, it goes without saying that such energy cannot exist at the center of a galaxy.
Note: One light-year = 9 461 000 000 000 km
Professor Cox claims that this rotation at the center of a galaxy is due to the following physical principle: the conservation of angular momentum. Gravity puts pressure on matter, which, under this contraction effect, rotates. Simply put, this principle operates when your sink empties of its water. For me, this particular notion is enough to explain the existence and functioning of a galaxy. Eureka!Gravity produces pressure on matter
There is a simple reason why there is a black hole at the center of a galaxy and not elsewhere in the galaxy: the pressure is uniformly distributed so that it is maximal at the center and minimal at the periphery. The closer to the center, the stronger the gravity. In other words, gravity increases with the increase of the number of celestial bodies per unit of space. However, this does not explain why there is only one center in a galaxy. Wouldn't it be more realistic to simply argue that a galaxy forms around a powerful black hole that attracts matter from its region? This view requires the assumption that a black hole precedes the formation of a galaxy, a prerequisite that seems unrealistic.
Gravity attracts and repels matter: attraction-repulsion
At the same time that gravity attracts the matter of the galaxy towards a center, an opposite force prevents the collapse of the galaxy on itself. We observe a similar phenomenon for any star, our Sun for instance. Gravity produces so much pressure on the matter of our Sun that it releases energy, heat. At the same time that this contraction allows the formation of the star, the energy that comes from it prevents it from collapsing on itself. This could well be what happens in the case of a galaxy. Research has shown that gravity has the ability to produce pressure on matter, which is much more visible when it comes to gas.
Gravity: where?
Gravity exists wherever there is matter. There is no place without gravity, no matter how small. Because gravity is not very perceptible in small matter, it does not mean that it does not exist. As the size of any object increases, there is an increase in pressure at the center of that object, which leads to more heat generation due to friction. But there must be friction: solid matter cannot give off heat.
This idea applies well to a single body. But what about a group of celestial bodies, a galaxy for example? What happens when there is an accumulation of celestial bodies in the same vicinity, like a million planets in a space the size of our solar system? It seems that this is how galaxies are formed and that a black hole appears in the center: this is my hypothesis. By accumulating matter in a given space, the phenomenon of conservation of angular momentum arises gradually and results in a rotation effect.
A legitimate doubt
Why doesn't this rotation effect have the ultimate consequence to swallow or absorb everything that comes near it? You are probably thinking of the image of your sink emptying. The gravity near the black hole (the place called the event horizon) does not come from the black hole, but from the matter surrounding the black hole. The matter near the black hole is held back by the rest of the stuff that makes up the galaxy. This widespread gravity in the galaxy seems to me to be sufficient to maintain an equilibrium and prevent a rapid absorption towards the center. Of course, any galaxy will eventually crash into itself when it becomes more concentrated.
What is true for a star seems to me to be true for a galaxy. Why not? One more reason to continue my questioning.....
At the same time that gravity attracts the matter of the galaxy towards a center, an opposite force prevents the collapse of the galaxy on itself. We observe a similar phenomenon for any star, our Sun for instance. Gravity produces so much pressure on the matter of our Sun that it releases energy, heat. At the same time that this contraction allows the formation of the star, the energy that comes from it prevents it from collapsing on itself. This could well be what happens in the case of a galaxy. Research has shown that gravity has the ability to produce pressure on matter, which is much more visible when it comes to gas.
Gravity: where?
Gravity exists wherever there is matter. There is no place without gravity, no matter how small. Because gravity is not very perceptible in small matter, it does not mean that it does not exist. As the size of any object increases, there is an increase in pressure at the center of that object, which leads to more heat generation due to friction. But there must be friction: solid matter cannot give off heat.
This idea applies well to a single body. But what about a group of celestial bodies, a galaxy for example? What happens when there is an accumulation of celestial bodies in the same vicinity, like a million planets in a space the size of our solar system? It seems that this is how galaxies are formed and that a black hole appears in the center: this is my hypothesis. By accumulating matter in a given space, the phenomenon of conservation of angular momentum arises gradually and results in a rotation effect.
A legitimate doubt
Why doesn't this rotation effect have the ultimate consequence to swallow or absorb everything that comes near it? You are probably thinking of the image of your sink emptying. The gravity near the black hole (the place called the event horizon) does not come from the black hole, but from the matter surrounding the black hole. The matter near the black hole is held back by the rest of the stuff that makes up the galaxy. This widespread gravity in the galaxy seems to me to be sufficient to maintain an equilibrium and prevent a rapid absorption towards the center. Of course, any galaxy will eventually crash into itself when it becomes more concentrated.
What is true for a star seems to me to be true for a galaxy. Why not? One more reason to continue my questioning.....
