A mysterious light from the center of the Milky Way may be the first revelation to our eyes of dark matter particles
Dark matter is one of the most insidious and elusive elements in the universe. It may take up about a quarter of the total mass and energy of the universe, but we can't know for sure because no one has actually seen it. Well, it may be finally unfolding before us.
NASA's Fermi Gamma-ray Space Telescope picked up high-energy gamma radiation originating from the center of the Milky Way, radiation that fits well with the theoretical prediction of dark matter. "To me, this is the most fascinating signal we've detected so far," said physicist Raphael Lang of Purdue University, who is not involved in the research, at the American Physical Society conference held in Savannah, Georgia in April 2014. If this light is indeed emitted from dark matter, then this is the first indirect detection of The particles that make up this dim mass.
Dark matter is apparently composed of what are called "weakly interacting mass particles" (WIMPs), particles that are their own antimatter, and therefore ionize each other when such a pair meets. Such ionization of WIMP particles produces normal matter particles and these generate gamma radiation photons. Since the dark matter is supposed to be most dense in the heart of the Milky Way, this is the best place to look for this light.
There have already been some hints that the Fermi telescope is picking up more light than expected from the center of the galaxy. But unlike the initial analysis that did not yield an unequivocal result, the new study found a clear signal: a larger-than-expected amount of gamma rays whose source extends at least 5,000 light-years from the center of the Milky Way (above). "It looks exactly like we've always thought dark matter should look," says Dan Hopper, one of the study's authors from the US Fermi National Accelerator Laboratory in Batavia, Illinois.
Obviously, extraordinary claims need extraordinary evidence. Most scientists refrain from expressing an opinion one way or the other before the signal is received by other devices or similar signals are also received from other places. But it is possible that the dark matter is already a little more visible.
The article was published with the permission of Scientific American Israel
29 תגובות
Israel
Do you know what expensive materials you are talking about? For an apple nanogram I would buy Gaza and with a basket of antimatter I would blow it up!
Yoda
If dark matter makes up most of the matter in the universe, why would it take its place here in Israel? Why can't you buy 2 kilos of dark matter and a basket of anti-matter in the market?
Bullying for its own sake.
Dear Israel
Regarding your question about the dark side of tomatoes, well for Friday Shabbat I made stuffed tomatoes and I didn't notice any dark side in them, not even in the peppers that were brilliantly added to them. But we will not deny that Albanzo's claim that there can be a dark side in the galaxy in general and in tomatoes in particular is within the framework of uncertainty (an apparently true claim) and since I cannot prove that this is not the case because dark matter has almost no taste and smell that is only dedicated to the expensive and good baryonic matter in general and tomatoes in particular, I will let Albanzo enjoy sex Doubt and I will enjoy the near lunchtime and the taste of the stuffed animals that playfully wink at me
Good Day
Sabdarmish Yehuda
Yoda
Why do you think that the sellers in the market don't really add some dark mass on the side of the tomatoes in the scales and that's how they bring a boost?
Yehuda,
You are systematically ignoring my words. First, I showed you explicitly (read the link I sent you!) that you are simply wrong when you write that the dark matter should not (or almost should not) be found in the center of the galaxy. Your assumption that if the deviation is far from the center then dark matter is needed there is simply wrong. Look at the models, look at the math, you will see that you are simply wrong. To correct the deviation away from the center you need to add dark matter *both* away from the center *and* in the center. It's in the formulas, black and white. Just read.
Second, you cannot choose which data to ignore and which not to. The fact that if you look only in the center you don't see a deviation from the expected speed from the centrifugal force alone is worth nothing if a little further away there is a deviation. You don't have the authority to choose which measurements you listen to and which you don't.
Bottom line - 1. There is a huge deviation between centripetal force alone and the measured speed. It needs to be fixed.
2. The correction of dark matter clearly contains dark matter in the center of the galaxy as well and not only at the edges as you claim in an obviously unfounded manner.
3. There is currently no other solution that both gives theoretical results that match the measurements and meets all the theoretical tests (such as, for example, that negative entropies and arbitrary temperatures that cannot be interpreted physically will not appear in it).
Keep arguing whatever you want, it doesn't change the reality. You are of course completely entitled to your opinion and entitled to express it in any forum you feel like, but when you simply ignore the facts - you cannot expect to be taken seriously.
Albanzo
First of all, the rotation in the center of the galaxy corresponds exactly to the gravitation of the material found there and this is clearly visible in the graph I sent you. True there is some uncertainty that you rely on, but I see no reason to add dark or non-dark matter there. There is also uncertainty in any measurement that depends on gravity, even of tomatoes in the market. Is it because of this that we are also sold dark tomato mass in the market or in the supermarket?, I find it hard to accept this. And if it appears that the tomatoes suddenly glow, will that mean that the glow is from a dark mass of tomatoes?, again I find this difficult to accept. There is also a bigger question, why do we only see the dark glow in the center of the galaxy where it should not be (almost), and not see it at the distances of the galaxy at a distance of one hundred to three hundred thousand light years from the center of the galaxy where most of the dark mass of the galaxy is concentrated in an amount of approximately A thousand billion solar masses. This figure is also theoretically supported.
In short, I don't think the dark mass is the explanation for the light shining in the center of the galaxy.
good week
Sabdarmish Yehuda
The profile I mentioned.
http://en.wikipedia.org/wiki/Navarro%E2%80%93Frenk%E2%80%93White_profile
Yehuda,
Ok. So you repeat your claim that it is impossible for there to be dark matter in the center of galaxies, and admit that it is possible but "with a low probability". Complete step one where you admit that your assertion that it is not possible was wrong. Now begins phase B where you will see that your assertion that the probability is low is also an assertion that is based on nothing but your principled hatred of dark matter.
1. First, if you admit that there is room for play with the distribution of dark matter that will still leave the graph in the area of the error crosses - how do you know exactly that the probability is low? Did you take the raw data, add dark matter and look at how much the graph moved? Have you checked how much dark matter has to be added before the graph moves more than a reasonable number of standard deviations away from the error cross? I guess not. If the answer is yes, please post your results and I will publicly and sincerely apologize. But assuming you haven't checked what is the gray range of dark matter that can be added in the center of the galaxy, how can you claim that the probability of this is low?
2. And as usual, you ignore that there is no need to play with the graph and add dark matter to it! As I already told you and you ignored, the beautiful graph you see, which fits the data perfectly, already includes dark matter in the center of the galaxy. The deduction that it includes dark matter only outside the galaxy is simply a mistake. For proof, I am attaching a link to the most popular profile of dark matter halos at the end of the comment.
If you look at the profile, you will see that if you look at a sphere of radius r around the center of the galaxy, where r is small relative to the typical width of the halo, you find that the amount of dark matter in this sphere (that is, right in the center of the galaxy) goes as the surface area of the sphere times the characteristic length times the average density of the dark matter. For galaxies with relatively large haloes this can reach *astronomical* amounts of dark matter, which is concentrated right in the center of the galaxy. And these are the models you see that give really perfect fits to the data. So in conclusion, our whole discussion about how much the graph would shift if we added more dark matter in the center and whether it would still fit the observations or not is a pointless discussion. Models with dark matter in the center of the galaxy fit the observations fantastically and you can even see it from the graphs you yourself brought!
Albanzo
Indeed, the uncertainty in measurements close to the center of the galaxy gives room for a dark mass in the center, but I still see this possibility as a small possibility. True [ small, but not zero.
Good night
Sabdarmish Yehuda
Yehuda,
Now I understand that you think that if the aberration is located far from the center of the galaxy, that means that the dark matter should sit far from the center of the galaxy. This is simply not true in general. Dark matter halos are *not* just outside the galactic center, but simply decay more slowly than baryonic matter and are therefore *also* outside the galactic center.
In addition, as you can see from the graphs you yourself referred to - all the measurements have error crosses (the measurement is not a point but a dashed line) and in the center of the galaxy the crosses are large. These crosses express exactly the inaccuracy in our measurements so even if you were right that a deviation away from the center means that dark matter can only exist far from the center, you clearly see that there is still freedom to move the theoretical graph without going beyond the observed data. And that is exactly what I was talking about and which you claimed was impossible. That is, your claim that if we add dark matter the theory and the observations will not match is not based on data (or theory), and these actually point to exactly the opposite claim (the dark matter halos that make the graphs match so beautifully with reality contain a large amount of dark matter also in the center of the galaxy and in addition There is a fairly large error factor so that there is no possibility of saying that "if we add dark matter everything will go wrong").
And as I said earlier, the problem you are exclusively focusing on - a mismatch between the rotation speed and the radiating mass - is only one aspect, and dark matter has evidence from other directions in physics as well. When several seemingly unrelated problems are solved by the same solution, this is very strong evidence of the correctness of the solution.
Albanzo
Of course, no one has studied the Milky Way from the outside and measured it, but we know that the Milky Way is a spiral galaxy and most likely the graphs expressing the speed of rotation of the galaxy as a function of distance are similar in all spiral galaxies and hence the dark mass is not required in the center of the galaxy but in the more distant periphery. You will understand that if they add the dark mass arbitrarily to the center of the galaxy it will spoil the equilibrium in the velocity measurement near the center of the galaxy. If that didn't convince you then I have no better proof.
In addition, Bell planted that I absolutely do not like the dark mass solution, because the problem in the galaxy is not a problem of gravitation at all, but rather a problem of incompatibility between two formulas: - of the gravitational force and the centrifugal force. The dark mass solution is only one of many possible solutions. But that's for another discussion.
Good night
Sabdarmish Yehuda
Sorry, it's not 1700 persec but about double the distance, as Yehuda said.
In any case, the huge deviation between the effect of the radiating mass alone and the true distribution as shown by the observations remains the same.
And now you just sent me a link to google images... ok. Sorry for the double post, don't know how it happened.
Yehuda,
What you presented does not in any way strengthen your claim that it is not possible for there to be a dark mass for milk. First, the graph refers to a different galaxy altogether. Second, it actually shows very clearly (regarding the galaxy in question) that your original claim is completely wrong - after a distance of about 1700 persec there is no longer a match between the radiating mass and the rotation speed and something must be added to explain the huge deviation. This article is about another possibility where the correction comes from masses that are not dark but are distant, based on Carati's proposal. This proposal is very problematic (and part of the criticism of it appears in the article you sent), mainly because it does retrofitting and cherry picking. Also, it has very, very non-trivial assumptions about the distribution of the distant matter. All in all, this is a rather lame explanation in my opinion.
That is, you did not answer the question at all (you did not show evidence that dark matter cannot be found for the Milky Way), but you changed the subject and pointed to an alternative explanation for the speed of rotation in spiral galaxies. This explanation is problematic, not exhaustive, and of course ignores the other evidence for the existence of dark matter (which stems from cosmological considerations - baryonic matter can only make up about 5% of the content of our universe).
Yehuda,
What you presented does not in any way strengthen your claim that it is not possible for there to be a dark mass for milk. First, the graph refers to a different galaxy altogether. Second, it actually shows very clearly (regarding the galaxy in question) that your original claim is completely wrong - after a distance of about 1700 persec there is no longer a match between the radiating mass and the rotation speed and something must be added to explain the huge deviation. This article is about another possibility where the correction comes from masses that are not dark but are distant, based on Carati's proposal. This proposal is very problematic (and part of the criticism of it appears in the article you sent), mainly because it does retrofitting and cherry picking. Also, it has very, very non-trivial assumptions about the distribution of the distant matter. All in all, this is a rather lame explanation in my opinion.
That is, you did not answer the question at all (you did not show evidence that dark matter cannot be found for the Milky Way), but you changed the subject and pointed to an alternative explanation for the speed of rotation in spiral galaxies. This explanation is problematic, not exhaustive, and of course ignores the other evidence for the existence of dark matter (which stems from cosmological considerations - baryonic matter can only make up about 5% of the content of our universe).
to Albenzo
Here is another collection of graphs that explain the situation in the spiral galaxy:
https://www.google.co.il/search?q=dark+matter+spiral+galaxy&client=firefox-a&hs=6EJ&rls=org.mozilla:en-US:official&channel=sb&tbm=isch&tbo=u&source=univ&sa=X&ei=leoJVLfIEtOO7Qb2l4HQDA&ved=0CFkQsAQ&biw=1266&bih=864
to Albenzo
There are many sources on the Internet that explain the location of the dark mass in the spiral galaxy
for example:
http://www.universetoday.com/91520/astronomy-without-a-telescope-could-dark-matter-not-matter/
The graph shows that up to a distance of about ten thousand light years from the center of the galaxy, the measured rotation speed and the rotation speed calculated from the apparent mass are the same. Beyond that, the calculated speed is getting smaller while the measured speed is increasing or maintaining its size and the possible explanation is the reality of another mysterious mass beyond ten thousand light years and up to hundreds of thousands of light years.
Yehuda
I forgot to put a link to Visser's article.
http://arxiv.org/pdf/1108.5240v4.pdf
Joseph,
I never said that the idea is a "vanity idea", but only that its evidence base does not come close to that of Lambda-CDM. I know the work of the Verlinda twins very well (and I also know them personally, one of the nicest people in the field. By the way, Herman is also a physicist and not a mathematician), but that does not change the fact that this idea is a sketch without "meat" and that no one has yet succeeded pick up the gauntlet and give her a boost of any kind in the last five years, including Eric Verlinda.
I don't know which Stringai review you're referring to (I'd appreciate it if you told me, and also if you told me what you think are the problems with his review), but there are a lot of unpublished reviews. In fact, the very fact that no one is actually working on the idea reflects the fact that it does not hold the same level of promise as many other ideas in the field of gravity that are being studied all over the world from morning to night. Besides, at the end of the day you don't need a fatal criticism that will make 100% sure that the idea should go to waste - it's enough that no one succeeds in promoting it and then even if we don't know if it's true or not, it's worthless as a scientific theory. This is exactly the criticism of string theory (and if you would like the opportunity I would be happy to explain why I think that in the case of strings this criticism is wrong. Full disclosure - I research string theory).
And two final things - the first is an inaccuracy regarding the Spinoza Prize. Eric received it for all his work in recent years, since his doctoral thesis until today. He did quite amazing things that won him world fame, with the leader probably being the fusion rules of the algebra you mentioned (which shed light on the tool that is probably the most important in string theory, the OPE in two-dimensional theory on the worldsheet). It's like saying that Gandhi deserves a Nobel Peace Prize for the non-violent protest in India and for the fact that he managed to reconcile a husband and wife who were fighting in the checkout line at the supermarket next to him.. 🙂
The second thing is Visser's criticism. I don't know if you talked about it or not (I have a feeling that not because he is not a string player and his criticism is not related to strings), but it is quite simple and therefore I think it is worth addressing. Although the article is poorly written, I do not find fault with it. At least not to the level that eliminates the need to refer to it - that is, someone has to pick up the gauntlet and show why his criticism is incorrect, and this has not happened in the last three years to the best of my knowledge.
Most importantly, I believe that string theory is correct, and there will be a unification of ideas, but of course I have no scientific basis for this belief.
I agree with your words about the scientific way. In the era of Daesh, and I think I said before that we may be entering the Second Intermediate Period, the scientific way is a light that must be guarded and never extinguished.
Verlind's "immature" idea received the Spinoza Prize, the Dutch Wolf Prize - a grant of about 2.5 million euros. is not a vanity idea. The algebra of the Verlind brothers is considered a serious mathematical work. There is a gifted mathematician brother to this Eric Verlind. like the Bernoulli brothers.
I read the criticism of the theory. The main article of the string theory researcher is long and written by a senior researcher, but I read it with a certain degree of depth out of a desire to discover the cracks from the mouth of a senior researcher, and in my opinion it is not convincing.
There was another article written by a Chinese researcher, who criticized gravitational entropy and he at least explained that the theory is consistent with basic principles of general relativity physics, currently only assuming the existence of conservation of energy and the existence of conservation of momentum at the moment. In this sense it is the beginning. We both agree that the debate is not settled.
Joseph,
You have presented these claims in the past and to the best of my recollection you have received answers.
First, you are absolutely right that currently the existence of matter is based on theoretical evidence only. I mean, we didn't find it, so we can't say that we know for sure that it exists. But it is important to understand the enormous importance of theoretical evidence - mathematical models do not turn out to be correct "by chance". The history of science is littered with theories that were supported only on paper and were found to be correct years later, when the means of measurement had advanced enough to allow them to be tested. I emphasize again that this is not a proof and that one cannot rely on theory alone, but if we did not underestimate the importance of theoretical evidence we would not have a standard model of the particles today, we would not have antiparticles, and it is even probable that there would be no general relativity.
So although it is possible that an alternative theory of gravity could explain all phenomena in the world without the need for dark matter, there is a problem with this: today, there is no such theory! Specifically, the theory you presented - Verlinda's entropic gravity, is not a theory. It is an immature idea that arose quite a number of years ago in scientific terms and since then no one, Verlinda or otherwise, has been able to promote it in any sense. Not to show that it explains phenomena that have not yet been explained, not to find a basis for an experiment that disproves the idea, and not even to deal with a fairly large number of mathematical problems in the model. So that doesn't mean the idea is definitely wrong, but it doesn't have a hundredth of the evidence or the theoretical foundation that a Lambda-CDM cosmological model that includes dark matter has.
In conclusion, all we have in science are hypotheses. But the scientific method is the tool through which we distinguish between hypotheses that are definitely not true (have been refuted), those that may be true, and those that are true with a very high degree of certainty. Until we hold dark matter in our hands, we cannot say that it exists, but it is impossible to put the theory that holds that it exists on the same shelf with theories of modified gravity in terms of the amount of evidence that supports them, as of today.
maybe one day…
Today, physics is looking for meanings for its importance in the important work being done at the LHC, and in the study of the universe. The importance of the other sciences has increased: computer science, medicine, biology, artificial intelligence. The time is not for mistakes and deceptions but for those who try, when it is clear that time may pass before a decision is made.
There are alternative theories for dark matter and the debate is not at all settled as shown in the article. They are called modified gravity, similar to the non-delusional ideas that Yehuda expresses. In addition, there is a theory by Dutch professor Erik Verlind, that by using the entropy of matter and without gravity at all, he derives gravity. This theory is also not as closed as it is not clear how the law of conservation of energy and momentum were created if Newton's laws are not assumed. Most importantly: dark matter is a hypothesis and there are other hypotheses that do not contain dark matter.
Yehuda,
Please provide a reference to the fact that the measurements of the rotation speed of the milky way versus the measurements of the light flux show that dark matter cannot exist in its center, and that every gram of dark matter in its center, if it were found, would result in a rotational movement that contradicts the one we measure.
Maybe I wasn't clear enough in my previous response: what I said was also true for spiral galaxies. In *certain* spiral galaxies it has been found that dark matter must exist far from the center of the radiating mass, but this does not mean that in other spiral galaxies, or even in the same spiral galaxies, dark matter cannot also exist within the distribution of the radiating mass. And contrary to your claim, our measurements of galaxy rotation and comparison to the amount of radioactive material do not approach the levels of precision that would allow us to rule out the existence of dark matter. After all, even estimating the amount of radiating mass is done in a rather crude way through the light flux. And in the published results from Fermi there is no guarantee that there will be a huge amount of dark matter in the center of the galaxy.
I would be very happy if you find an error in what I said and bring evidence with reference to sufficiently accurate measurements that can rule out the existence of dark matter for the milk. Before you go on a quest to find such evidence, remember that today there are relatively many experiments on the surface of the Milky Way aimed at detecting dark particles, and ask yourself if anyone would invest many millions of dollars in these detectors and experiments if we had proof that there is no dark matter in the Milky Way, as you Claims my understanding.
to Albantezo
I'm just referring to the article right now and they're talking about the center of the Milky Way. And about the Milky Way which is a reactive spiral galaxy. You can't just put dark matter into any place and ignore the gravity it contributes to that place. If there is dark matter in the center of the Milky Way in addition to the normal mass then it will cause an additional rotation of the matter around it, which contradicts the measurements. The centrifugal force corresponds exactly to that due to the mass near the center. Anyone who adds mass (dark or not) to a region detracts and spoils the calculations!
It seems to me that this is a phenomenon that can possibly be explained by the black hole in the center of the Milky Way.
In the meantime, this phenomenon has not been seen in other galaxies, so there is a great deal to be said about it, and maybe I'm missing something?
Good Day
Sabdarmish Yehuda
Sabdarmish Yehuda,
Just because the first motivation for dark matter came from spiral galaxies doesn't mean that's all we know about it. Today there are very precise ways to locate dark matter with the help of investigating the effects of gravitational dusting that shows where and how the matter is distributed in space, and comparing it to the light emitted from the area (and thus it is possible to separate between radiating gravitational material and non-radiating gravitational material, i.e. - dark).
You claim that since the motivation for dark matter came (in part, DA) from the fact that there seemed to be a lack of matter at the edges of certain galaxies, then dark matter can only be found at the edges of galaxies. But this is not true and today's observations show that dark matter can also be found in the centers of galaxies, in the interstellar medium or inside our toaster. Obviously - the place where we first detected evidence of its existence is the place where most of the dark matter is far from most of the normal matter because in these places it causes the most obvious deviation from the predictions of gravity without dark matter.
This is equivalent to the arrival of invisible people. Obviously, the first places where they will discover the people are deserts (where they will see footprints suddenly appear without a person leaving them), very rainy places (where they will notice that it is raining but part of the ground remains dry, as if someone is standing on it and protecting it from the rain), etc. It will be very difficult to recognize them when they walk around to their pleasure in the Haaretz Museum, but that doesn't mean they aren't there.
Physics is a bit lost in unclear areas while fields such as artificial intelligence, biology and medicine are making great strides. Where are the spirit giants of physics.
From calculations of gravitation and centrifugal force of a spiral galaxy, the dark matter should be very far from the center of the galaxy and there is no need for dark matter in the center of the galaxy because the gravitation of the normal mass in the center is sufficient for the rotation resulting from it in the center. So it's strange that any phenomenon in the center of the galaxy would be explained by dark matter that shouldn't be there at all.
But what do I understand?
Good night
Sabdarmish Yehuda