Hey Fermilab, I am a teenager who is greatly admired by physics (especially relativity and quantum mechanics). Your videos helped me develop a very good understanding towards them. Best wishes from my side for creating more such videos often
TH-cam is awesome... Free knowledge (almost free .. I pay for the ad free version) in almost any domain .... Music theory, mathematics, physics ... This is such a great time to be alive !!!!
In Dan Bauer’s slides “Dark Matter Cluster Collisions” he shows that matter does not interact with dark matter, but the next slides argue matter would not have formed galaxies without a dark matter lattice to attract it. I am probably missing some key points, but this inconsistency doesn’t make sense to me.
Dark matter can still interact gravitationally. It has mass and can warp spacetime around it. When they say it doesnt interact, they mean through electromagnetic interaction. Dark matter is "invisible" in terms of electromagnetism
I understand, but it seems like there is an inconsistency. The galaxy clusters normal mass interacts gravitationally, while the dark matter continues past the normal matter without (significant?) interaction. I may not be understanding the point of the galaxy cluster collision simulation.
I think the x-ray observations showed intergalactic gas clumping toward the center of the colliding clusters but the gravitational lensing showed most of the mass of the cluster was out in front of the two systems that colided
What is the basis for the assumption that the "dark" source of the "extra" gravitational attraction is some form of matter? In other words, that the sources are highly localized in 3D-space, like "particles" are.
The extra mass seems to be around galaxies, confined to them in a gaseous way. If the were massless or near massless they would escape the gravitational wells of the galaxies similarly to photons or neutrinos.
@@ristopaasivirta9770 You complicate things too much; when we fit observed density profiles for an ideal fluid to Friedman's eqs, we get, i.a., a term independent of the scale factor (we call that "dark energy"), and one proportional to the scale factor^-3, part of which is accounted by "ordinary" (luminous) matter, and the rest we call "dark matter". I.e., it's a fitting job. Simple as that.
I thing historically, the thing went like this. Astronomers measured the masses and the rotation curves of galaxies and saw that didn't follow Newton's law. So, they had two options. One, our gravity laws are wrong and have to make others, or two, we must be missing matter when weighting the galaxies. From their point or view, I think the second option was the most logical. For more histories from the underbelly of Cosmology, I recommend tritonstation.com
The paper where is described a solution of the rotational velocities observed in spiral galaxies and of their spiral geometry from the general relativity, without using dark matter, is the following: article.sapub.org/10.5923.j.astronomy.20200902.01.html
Isn't the question regarding dark matter forming structures already answered with the idea that it clumped together to form the galactic filaments? It might not be the same as molecules as we know it, but it is something. Perhaps the filaments are a small part of a larger structure beyond the observable universe?
Could dark matter possibly interact via the Higgs Field and the Higgs Field only? I’m not very knowledgeable on the subject (just a first year college student who reads about physics as a hobby) but I do know that mass is a result of interactions with the Higgs Field.
If we know that Higgs field exists and mass of a particle is due to their interaction with the field. Then mass of a particle is extrinsic in quantum physics. But in string theory mass of a string (particle) is given by the energy it creates with the tension or something of that sort which makes mass Intrinsic. In a way one theory contradicts the other. I couldn't find any answer to this on the web could you help me?
@@averycuriousclumpofatom2159 Within the framework of the standard model, given the lack of gravitons in the standard model, wouldn’t dark matter have to interact with some non-gravitational field that also interacts with normal matter to have a mass? This frame of thought may only be relevant for gauge bosons, but I’m not sure since I’m pretty sure the Higgs fields main purpose was to provide a mechanism by which gauge bosons could have mass.
@@mdnadeemazam4382 From what I read, it seems that the mass provided by the Higgs field is mostly (if not only) relevant for gauge bosons. I’m not very familiar with string theory since a lot of my particle physics knowledge comes from particle astrophysics and cosmology (I kind of get field theory by also I am nearly clueless about the mathematical concepts and equations applied in the theory so I’m kind of at a loss )
@@averycuriousclumpofatom2159 - But mass and gravitational force seem to be the same thing, sorta. Technically gravity is not a "force" but the bending of spacetime because of another "force": mass. Anyhow, unraveling this beyond what I just is like the Gordian Knot of fundamental physics. So the Higgs field is still relevant but probably not enough. Something like a "neutron" (but that is stable) would work better (as it's much more massive than fundamental particles only massified by the Higgs field).
21:18 Ya know... I wasn't concerned until you said I shouldn't be. The *probability* of a dark matter interaction is low but uhhhh... what happens if all the particles passing through my head decided its their time to shine all at once?
I thought the same thing years ago, I always figure if I can come up with ideas like that, and so can you in this case, then so can the people who understand the math much better than you or I. If I guess i would say that like so many other explanations of dark matter, this effect has likely been calculated and found to be too small to explain dark matter alone
@@kx4532 I would start with a subscription to brilliant, the best educational TH-cam's all seem to love it.. Youd need to be able to use calculus effectively and learn a lot of different notations.. Im not sure where to start but I would suggest checking out brilliant i guess it's .com
Perhaps you know this already, but "frame-dragging" is really just the GR equivalent of Foucault's pendulum; the clearest examples to date are the Lense-Thirring effect, which is approximate, and in the Kerr solution. Because of this, I don't think anyone has seriously considered to apply it to galaxies specifically - though in principle it might be done, and I myself suspect this is prolly the case/(partial) expo for DM due to things like the Einstein-de Haas experiment and certain gauge generalizations of GR which people have proposed over the years; there's a ECSK guy in particular (Nikodem J. Poplawski) who loves to proclaim spin as a panacea - so maybe he _did_ make a frame-dragging calculation, in one of his many papers...
What I don't understand is why it is referred to as matter, dark gravity actually describes what is seen. Dark matter displays no properties of matter except gravitation, especially not mass. I suppose it's our inability to conceive of gravitation in the absence of mass that causes this. This is exactly what must be accepted. This describes a novel particle class.
Simply modifying gravity does not explain why we see some galaxies with much dark matter than they should have or extremely little. Also it doesnt explain observations like the bullet cluster. Basically it has to be some kind of "stuff" to fit observation
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I'm just gonna throw my two hypotheses about dark matter out there and watch them get torpedoed. 1. Dark matter may be very large and broad in scale, and may not have sub-atomic particles at all (like trying to measure the tide compared to waves). 2. Dark matter might actually be a semi-permanent "dent" in the fabric of space-time. We know that matter bends space-time to cause the effect we call gravity (and gravity is the (only way?) we're able to observe dark matter), but what if space-time isn't perfectly uniform? What if space-time can be curved in places, without having matter directly affecting it?
Why are we actually so sure, we can measure the mass of galaxies by observing their light? Why there aren’t just more stars and black holes inside galaxies, which we don’t see? What if our measuring is just wrong and we don’t get the real amount of stars, black holes or other “normal objects”?
This was cool, though I wonder how annoyed these people were to drop their research to draw up simplified and understandable presentations good for even curious laymen. I'm wondering if there's any possible test for string theory; a proposed next dimension, which might account for unexplained gravity. I also wonder if there's a way to test for a possible link with dark energy. Even weirder, if loop quantum gravity has any weight, that would throw a curve ball at this research
The solar system is 5 billion years old and is traveling at about 500,000 mi/h. So if no force was acting upon the sun except the weak nuclear force producing a slow acceleration as new energy is produced from nuclear fusion then we would simply take it's age and divide it by it's current velocity in order to get it's acceleration rate over time. 5 billion / 500,000 = 10,000 Meaning for every 10,000 years the solar system increased in speed or accelerated 1 mi/h. So if we break down this distance to time we get a slow acceleration rate of 0.0000002007 inches a second. That is an acceleration rate less than the width of a proton per second. Talk about extremely slow acceleration rate. Every second of every day the solar system increases it's velocity by 0.0000002007 in/s. It takes a full 10,000 years for the solar system to increase it's velocity by just 1 mi/h (1.609344 km/h) The Milky Way galaxy is 13.7 billion years old and is traveling about 1.37 million mi/h. It has the same acceleration rate as our solar system. A 1 mi/h increase in velocity every 10,000 years. Dark matter is a wild way to say Einstein's general relativity and Newtons laws of gravity equations are incomplete.
Going by their description of it, no it wouldn't. DM doesn't interacts with electromagnetic waves aka light so you wouldn't notice a difference with the source
Hi, maybe you mean that the amount of Dark Energy is increasing as the Universe expands( its density remains constant,no,no kidding,remains constant) and Dark Matter( and Barionic too) densities are diluting with that expansion.
In 2013 the Planck spacecraft observations of the cosmic microwave background gave an estimate of *68.3%* dark energy, *26.8%* dark matter, and *4.9%* baryonic matter. 💕 ☮ 🌎 🌌
Maybe dark matter is not an exotic form of matter but is really just cold neutral hydrogen in its lower 1 s ground state? Hydrogen in this state would not emit light but would have mass and be very slow moving. Through atomic excitation, dark matter becomes visible matter. We know that clouds of hydrogen gas surrounds most galaxies at 5 to 10x the size of what we see as the visible galaxy. One way to prove whether or not dark matter is actual the lower ground state of Hydrogen is to look at two galaxies on a collision course. You should see visible matter where dark matter once was. We know hydrogen is the most common atomic element in the universe. I always take the approach that it’s better to validate or reject a simpler explanation before exploring more complex and exotic theories.
Hi, I think not. Atomic H spectroscopy has been a very important measure in Astrophysics from the moment the first radiotelescopes were turned on. Look for the 21 cm line and Ltman series. Bottom line, H atoms are very easy to see in the sky.
Also if Dark Matter does not interact with matter how is it that seeded Galaxy formation is thought of as proof IE forming the cosmic web... What would it be that causes matter to follow the same path if not interaction? 5:56
So first off, you’re telling me dark matter is everywhere. Then you go on telling me that dark matter can be black holes at the beginning of the universe. Then you say that the big bang was infinitesimally small and happened everywhere. Then would it not make sense that the dark matter is the big bang still happening at a really small scale because it’s really really small and it’s everywhere. Don’t take my word for it, I’m just another Joe
Expansion of the universe is not actually acceleration, it's an illusion caused by a gravitational dopplar shift. For the same reason that gravitational lensing happens, gravity distorts the frequency of light emitted from distant galaxies. Gravity causes a time-space distortion that redshifts its photons throughout their journey to you. The further away a galaxy is, the more time its photons are distorted at an exponentially reduced value as their distance from the galaxy's gravitational field increases. Galaxies are much further away than measurements indicate, although they typically aren't accelerating away from you. Dark energy is an illusion caused by a spacial distortion caused by the gravitational fields of the distant galaxies emitting the light, there is no mysterious energy accelerating galaxies away from you, no dark energy causing acceleration, no unaccounted for dark matter, and certainly, no big bang. This universe is eternal, without beginning or ending. Cosmic background microwaves are but distant galaxies who's light has been gravitationally distorted beyond your visible spectrum.
3 ปีที่แล้ว +1
Since dark matter doesn't exist how do they also look for big foot?
Definitely not a myth lol we already can detect it by observing it's influence. What they mean is other ways of detecting in order to rule out what it isn't, as opposed to revealing what it is.
Can't find something if it doesn't exist. General relativity is incomplete. Einstein and Newton never addressed the action causing gravity in their equations. If they included the action causing gravity they would have predicted the slow acceleration that occurs to solar systems and galaxies. Stars and galaxies accelerate at the same rate regardless of the amount of mass they contain or the distance between. Gravitation lensing is a mirage because light bends and distorts as it passes through a heated medium, like the corona of the sun or the heated gas between clusters of galaxies that are near one another. The reason why stars have not reached the escape velocity of galaxies is because the stars in the galaxy accelerate so slow that they are not able to escape. I deduced the acceleration rate of stars and galaxies to be 2.007x10-7 in/s. That is an acceleration rate less than the width of a proton per second. Thus no matter how much speed they build over time they will never reach the velocity to escape the galaxy's gravity. Dark matter is simply the mistake assuming that gravity is the only force in the universe able to move mass when it is not. Mass and gravity are not causing stars and galaxies throughout the universe to accelerate at 2.007x10-7 in/s. For if gravity was causing the acceleration then the acceleration would always be different for stars and galaxies. But their velocities are clearly the same. Do the math yourself. The image of the Bullet cluster was done in X-ray, gamma ray and visual light. It does not indicate any dark matter. Assuming so would be grasping for straws and getting forked.
There is no dark matter. It is a misunderstanding caused by the finite speed of light. Read the explanation in a Short Treatise on the Space Time Continuum by Piankh.
@@Hookooo I am not an expert. Scientists have noticed that their isn t enough matter to keep galaxies together. They should not stick together due to the speed rotation. So there is dark matter that has been introduced to explain the observation and complete the mass that we can t observe. And in the other hand as we noticed that the expansion of the universe is accelerating we introduced dark energy to explain it. But all over the world there are experiments that try to find neutrinos (particle of dark matter). Nothing has bee. Found yet. There are other scientist that try to find another theory to explain the missing matter and the expansion of the universe. They are just another theory as the negative mass for exemple. My comment was just a call to find another solution to dark matter which is supposed to represent around 70% of the mass of the universe. And sorry it was not meant to criticize or to be negative. Just a call for fresh ideas
Dark matter now is so embedded in the lambdaCDM model of Cosmology that is really a paradigm. If you look at History, you see that a lot of people have to die off before a paradigm changes, no matter its troubles. Another problem is what will sustitute it. I am parcial to MOND, but a convincing relativistic extension is still in the future, there istha CMB data to account to... A messy problem. Time will tell, hopefully.
@@eljcd I absolutely agree. I just regret that there are very few people that try to find another path to darkmatter. And it looks like it is very difficult for many scientists to just be allowed to look in other directions just because as you said it it is too much embedded in the theory...
the problem with mond isn't that "there's no way GR could be wrong", the problem with mond is that it doesn't work. From reddit: Below is basically a historical approach to why we believe in dark matter. I will also cite this paper for the serious student who wants to read more, or who wants to check my claims agains the literature. In the early 1930s, a Dutch scientist named Jan Oort originally found that there are objects in galaxies that are moving faster than the escape velocity of the same galaxies (given the observed mass) and concluded there must be unobservable mass holding these objects in and published his theory in 1932. Evidence 1: Objects in galaxies often move faster than the escape velocities but don't actually escape. Zwicky, also in the 1930s, found that galaxies have much more kinetic energy than could be explained by the observed mass and concluded there must be some unobserved mass he called dark matter. (Zwicky then coined the term "dark matter") Evidence 2: Galaxies have more kinetic energy than "normal" matter alone would allow for. Vera Rubin then decided to study what are known as the 'rotation curves' of galaxies and found this plot. As you can see, the velocity away from the center is very different from what is predicted from the observed matter. She concluded that something like Zwickey's proposed dark matter was needed to explain this. Evidence 3: Galaxies rotate differently than "normal" matter alone would allow for. In 1979, D. Walsh et al. were among the first to detect gravitational lensing proposed by relativity. One problem: the amount light that is lensed is much greater than would be expected from the known observable matter. However, if you add the exact amount of dark matter that fixes the rotation curves above, you get the exact amount of expected gravitational lensing. Evidence 4: Galaxies bend light greater than "normal" matter alone would allow. And the "unseen" amount needed is the exact same amount that resolves 1-3 above. By this time people were taking dark matter seriously since there were independent ways of verifying the needed mass. MACHOs were proposed as solutions (which are basically normal stars that are just to faint to see from earth) but recent surveys have ruled this out because as our sensitivity for these objects increase, we don't see any "missing" stars that could explain the issue. Evidence 5: Our telescopes are orders of magnitude better than in the 30s. And the better we look then more it's confirmed that unseen "normal" matter is never going to solve the problem The ratio of deuterium to hydrogen in a the present universe is known to be proportional to the density of the universe. The observed ratio in the universe was discovered to be inconsistent with only observed matter... but it was exactly what was predicted if you add the same dark mater to galaxies as the groups did above. Evidence 6: The deuterium to hydrogen ratio is completely independent of the evidences above and yet confirms the exact same amount of "missing" mass is needed. The cosmic microwave background's power spectrum is very sensitive to how much matter is in the universe. As this plot shows here, only if the observable matter is ~4% of the total energy budget can the data be explained. Evidence 7: Independent of all observations of stars and galaxies, light from the big bang also calls for the exact same amount of "missing" mass. This image may be hard to understand but it turns out that we can quantify the "shape" of how galaxies cluster with and without dark matter. The "splotchiness" of the clustering from these SDSS pictures match the dark matter prediction only. Evidence 8: Independent of how galaxies rotate, their kinetic energy, etc... is the question of how they cluster together. And observations of clustering confirm the necessity of vats of intermediate dark matter" One of the recent most convincing things was the bullet cluster as described here. We saw two galaxies collide where the "observed" matter actually underwent a collision but the gravitational lensing kept moving un-impeded which matches the belief that the majority of mass in a galaxy is collisionless dark matter that felt no colliding interaction and passed right on through bringing the bulk of the gravitational lensing with it. Evidence 9: When galaxies merge, we can literally watch the collisionless dark matter passing through the other side via gravitational lensing. In 2009, Penny et al. showed that dark matter is required for fast rotating galaxies to not be ripped apart by tidal forces. And of course, the required amount is the exact same as what solves every other problem above. Evidence 10: Galaxies experience tidal forces that basic physics says should rip them apart and yet they remain stable. And the amount of unseen matter necessary to keep them stable is exactly what is needed for everything else. There are counter-theories, but as Sean Carroll does nicely here is to show how badly the counter theories work. They don't fit all the data. They are way more messy and complicated. They continue to be falsified by new experiments. Etc... To the contrary, Zwicky's proposed dark matter model from back in the 1930s continues to both explain and predict everything we observe flawlessly across multiple generations of scientists testing it independently. Hence dark matter is widely believed. Evidence 11: Dark matter theories have been around for more than 80 years, and not one alternative has ever been able to explain even most of the above. Except the original theory that has predicted it all. Conclusion: Look, I know people love to express skepticism for dark matter for a whole host of reasons but at the end of the day, the vanilla theories of dark matter have passed literally dozens of tests without fail over many many decades now. Very independent tests across different research groups and generations. So personally I think that we have officially entered a realm where it's important for everyone to be skeptical of the claim that dark matter isn't real. Or the claim that scientists don't know what they are doing. Also be skeptical when the inevitable media article comes out month after month saying someone has "debunked" dark matter because their theory explains some rotation curve from the 1930s. Skeptical because rotation curves are one of at least a dozen independent tests, not to mention 80 years of solid predictivity.
You may be correct that Dark Matter does not exist however there is data on the motions in our galaxy and universe at large that need an explanation, Dark Matter is one hypothesis that if found could explain what we observe within the current framework of our understanding. Perhaps dark matter is just an artifact of current theory. Without the science being done we should not know.
@@woodstockjon420 : A devil's advocate would point out the difference between spending tax dollars searching for dark matter versus spending private dollars "searching" (philosophizing?) for God. (A devil's advocate might also recommend wasting a lot more dollars.) It's unknown whether the search to understand dark matter will ever deliver any practical public benefits (beyond peace of mind for a few thousand physicists and cosmologists) but presumably there's a chance it will someday deliver major benefits. (Assuming the vast bulk of humanity doesn't first get enslaved by weaponized advances in neuroscience research).
This was great. The value of this content and the access to professors and professionals at the top of their respective fields for free is priceless.
Wheres is Doc Lincoln? Release the Lincoln.
The cages are opening, releasing the beast
@@manavmnair6975 Jurassic vibes?
@@littlechineseladyv2517 yes
i miss him so bad 😟
Oh, great! I'll take a nice break from my constant Zoom conferences with a... Oh.
Good one mate
ZOOM HELL
This will blow your mind. Find the "About" tab on my channel with info to read and a link, go to the link and click on "created playlists".
Oh yeah. Im in the same boat
Count Dooko gave a lovely talk
Hey Fermilab,
I am a teenager who is greatly admired by physics (especially relativity and quantum mechanics). Your videos helped me develop a very good understanding towards them. Best wishes from my side for creating more such videos often
TH-cam is awesome... Free knowledge (almost free .. I pay for the ad free version) in almost any domain .... Music theory, mathematics, physics ... This is such a great time to be alive !!!!
In Dan Bauer’s slides “Dark Matter Cluster Collisions” he shows that matter does not interact with dark matter, but the next slides argue matter would not have formed galaxies without a dark matter lattice to attract it. I am probably missing some key points, but this inconsistency doesn’t make sense to me.
Dark matter can still interact gravitationally. It has mass and can warp spacetime around it. When they say it doesnt interact, they mean through electromagnetic interaction. Dark matter is "invisible" in terms of electromagnetism
I understand, but it seems like there is an inconsistency. The galaxy clusters normal mass interacts gravitationally, while the dark matter continues past the normal matter without (significant?) interaction. I may not be understanding the point of the galaxy cluster collision simulation.
I think the x-ray observations showed intergalactic gas clumping toward the center of the colliding clusters but the gravitational lensing showed most of the mass of the cluster was out in front of the two systems that colided
What is the basis for the assumption that the "dark" source of the "extra" gravitational attraction is some form of matter? In other words, that the sources are highly localized in 3D-space, like "particles" are.
The extra mass seems to be around galaxies, confined to them in a gaseous way. If the were massless or near massless they would escape the gravitational wells of the galaxies similarly to photons or neutrinos.
@@ristopaasivirta9770 You complicate things too much; when we fit observed density profiles for an ideal fluid to Friedman's eqs, we get, i.a., a term independent of the scale factor (we call that "dark energy"), and one proportional to the scale factor^-3, part of which is accounted by "ordinary" (luminous) matter, and the rest we call "dark matter". I.e., it's a fitting job. Simple as that.
I thing historically, the thing went like this. Astronomers measured the masses and the rotation curves of galaxies and saw that didn't follow Newton's law. So, they had two options. One, our gravity laws are wrong and have to make others, or two, we must be missing matter when weighting the galaxies. From their point or view, I think the second option was the most logical. For more histories from the underbelly of Cosmology, I recommend
tritonstation.com
“The triumph of mind over matter.
What is mind? No matter.
What is matter? Never mind.”
/”Carry on doctor” - the movie 1967/
Hahaha great movie
The paper where is described a solution of the rotational velocities observed in spiral galaxies and of their spiral geometry from the general relativity, without using dark matter, is the following:
article.sapub.org/10.5923.j.astronomy.20200902.01.html
Isn't the question regarding dark matter forming structures already answered with the idea that it clumped together to form the galactic filaments? It might not be the same as molecules as we know it, but it is something. Perhaps the filaments are a small part of a larger structure beyond the observable universe?
Could dark matter possibly interact via the Higgs Field and the Higgs Field only? I’m not very knowledgeable on the subject (just a first year college student who reads about physics as a hobby) but I do know that mass is a result of interactions with the Higgs Field.
If we know that Higgs field exists and mass of a particle is due to their interaction with the field.
Then mass of a particle is extrinsic in quantum physics.
But in string theory mass of a string (particle) is given by the energy it creates with the tension or something of that sort which makes mass Intrinsic.
In a way one theory contradicts the other.
I couldn't find any answer to this on the web could you help me?
Well dark matter interacts with the gravitational force
@@averycuriousclumpofatom2159 Within the framework of the standard model, given the lack of gravitons in the standard model, wouldn’t dark matter have to interact with some non-gravitational field that also interacts with normal matter to have a mass? This frame of thought may only be relevant for gauge bosons, but I’m not sure since I’m pretty sure the Higgs fields main purpose was to provide a mechanism by which gauge bosons could have mass.
@@mdnadeemazam4382 From what I read, it seems that the mass provided by the Higgs field is mostly (if not only) relevant for gauge bosons. I’m not very familiar with string theory since a lot of my particle physics knowledge comes from particle astrophysics and cosmology (I kind of get field theory by also I am nearly clueless about the mathematical concepts and equations applied in the theory so I’m kind of at a loss )
@@averycuriousclumpofatom2159 - But mass and gravitational force seem to be the same thing, sorta. Technically gravity is not a "force" but the bending of spacetime because of another "force": mass.
Anyhow, unraveling this beyond what I just is like the Gordian Knot of fundamental physics.
So the Higgs field is still relevant but probably not enough. Something like a "neutron" (but that is stable) would work better (as it's much more massive than fundamental particles only massified by the Higgs field).
Anxious for exciting results from G-2 sometime in 2021!
21:18
Ya know... I wasn't concerned until you said I shouldn't be. The *probability* of a dark matter interaction is low but uhhhh... what happens if all the particles passing through my head decided its their time to shine all at once?
Can someone tell me if were sure dark matter isn't frame dragging on a galactic scale.
I thought the same thing years ago, I always figure if I can come up with ideas like that, and so can you in this case, then so can the people who understand the math much better than you or I. If I guess i would say that like so many other explanations of dark matter, this effect has likely been calculated and found to be too small to explain dark matter alone
@@seionne85 Where do you look up this kind of math. Everything I find is vague and nothing really walks you through it.
@@kx4532 I would start with a subscription to brilliant, the best educational TH-cam's all seem to love it.. Youd need to be able to use calculus effectively and learn a lot of different notations.. Im not sure where to start but I would suggest checking out brilliant i guess it's .com
@@kx4532 hey look up Parth G he does great detailed explanations of the "maths" lol
Perhaps you know this already, but "frame-dragging" is really just the GR equivalent of Foucault's pendulum; the clearest examples to date are the Lense-Thirring effect, which is approximate, and in the Kerr solution. Because of this, I don't think anyone has seriously considered to apply it to galaxies specifically - though in principle it might be done, and I myself suspect this is prolly the case/(partial) expo for DM due to things like the Einstein-de Haas experiment and certain gauge generalizations of GR which people have proposed over the years; there's a ECSK guy in particular (Nikodem J. Poplawski) who loves to proclaim spin as a panacea - so maybe he _did_ make a frame-dragging calculation, in one of his many papers...
Please also make video on dark energy
What I don't understand is why it is referred to as matter, dark gravity actually describes what is seen. Dark matter displays no properties of matter except gravitation, especially not mass. I suppose it's our inability to conceive of gravitation in the absence of mass that causes this. This is exactly what must be accepted. This describes a novel particle class.
Simply modifying gravity does not explain why we see some galaxies with much dark matter than they should have or extremely little. Also it doesnt explain observations like the bullet cluster. Basically it has to be some kind of "stuff" to fit observation
Theres nothing wrong with the idea of matter that only interacts via gravity.
If you are interested in innovation, check here. Find the "About" tab on my channel with info to read and a link, go to the link and click on "created playlists".
I'm just gonna throw my two hypotheses about dark matter out there and watch them get torpedoed.
1. Dark matter may be very large and broad in scale, and may not have sub-atomic particles at all (like trying to measure the tide compared to waves).
2. Dark matter might actually be a semi-permanent "dent" in the fabric of space-time. We know that matter bends space-time to cause the effect we call gravity (and gravity is the (only way?) we're able to observe dark matter), but what if space-time isn't perfectly uniform? What if space-time can be curved in places, without having matter directly affecting it?
Why are we actually so sure, we can measure the mass of galaxies by observing their light? Why there aren’t just more stars and black holes inside galaxies, which we don’t see? What if our measuring is just wrong and we don’t get the real amount of stars, black holes or other “normal objects”?
Very informative - thanks for sharing!
Has anyone observed why CERN youtube channel, PBS spacetime and Fermilab, all have posted dark matter videos on the same day?? 🤔🤔
I've observed them doing it, not "why" tho, i think it'd be very hard to observe such a thing from an outsider's pov
@@Ebani thanks
This will blow your mind. Find the "About" tab on my channel with info to read and a link, go to the link and click on "created playlists".
Could dark matter be related to magnetism?
This was cool, though I wonder how annoyed these people were to drop their research to draw up simplified and understandable presentations good for even curious laymen.
I'm wondering if there's any possible test for string theory; a proposed next dimension, which might account for unexplained gravity.
I also wonder if there's a way to test for a possible link with dark energy.
Even weirder, if loop quantum gravity has any weight, that would throw a curve ball at this research
The solar system is 5 billion years old and is traveling at about 500,000 mi/h. So if no force was acting upon the sun except the weak nuclear force producing a slow acceleration as new energy is produced from nuclear fusion then we would simply take it's age and divide it by it's current velocity in order to get it's acceleration rate over time. 5 billion / 500,000 = 10,000 Meaning for every 10,000 years the solar system increased in speed or accelerated 1 mi/h. So if we break down this distance to time we get a slow acceleration rate of 0.0000002007 inches a second. That is an acceleration rate less than the width of a proton per second. Talk about extremely slow acceleration rate. Every second of every day the solar system increases it's velocity by 0.0000002007 in/s. It takes a full 10,000 years for the solar system to increase it's velocity by just 1 mi/h (1.609344 km/h)
The Milky Way galaxy is 13.7 billion years old and is traveling about 1.37 million mi/h. It has the same acceleration rate as our solar system. A 1 mi/h increase in velocity every 10,000 years. Dark matter is a wild way to say Einstein's general relativity and Newtons laws of gravity equations are incomplete.
Does dark matter leave a shadow?
Going by their description of it, no it wouldn't. DM doesn't interacts with electromagnetic waves aka light so you wouldn't notice a difference with the source
We want more Don Lincoln!
After reading all the comments, I feel like I may have lost some brain cells.
With a flashlight, duh!
Is dark matter weakly interacting with photons?
No
Is the amount of dark matter increasing as the universe expands, or is dark matter diluting with expansion of universe?
Hi, maybe you mean that the amount of Dark Energy is increasing as the Universe expands( its density remains constant,no,no kidding,remains constant)
and Dark Matter( and Barionic too) densities are diluting with that expansion.
@@eljcd sounds good
In 2013 the Planck spacecraft observations of the cosmic microwave background gave an estimate of *68.3%* dark energy, *26.8%* dark matter, and *4.9%* baryonic matter.
💕 ☮ 🌎 🌌
Maybe dark matter is not an exotic form of matter but is really just cold neutral hydrogen in its lower 1 s ground state? Hydrogen in this state would not emit light but would have mass and be very slow moving. Through atomic excitation, dark matter becomes visible matter. We know that clouds of hydrogen gas surrounds most galaxies at 5 to 10x the size of what we see as the visible galaxy. One way to prove whether or not dark matter is actual the lower ground state of Hydrogen is to look at two galaxies on a collision course. You should see visible matter where dark matter once was. We know hydrogen is the most common atomic element in the universe. I always take the approach that it’s better to validate or reject a simpler explanation before exploring more complex and exotic theories.
Hi, I think not. Atomic H spectroscopy has been a very important measure in Astrophysics from the moment the first radiotelescopes were turned on.
Look for the 21 cm line
and Ltman series.
Bottom line, H atoms are very easy to see in the sky.
Does dark matter move the earth and stars inside galaxies?
Axions = dark matter
I've been searching for pixies.......
Looking for dark matter? Can you even find a fatty liver? Start with that.
It's my opinion that it is just a flaw in our understanding of gravity... regardless of the many viewpoints I hope we find the solution in my lifetime
Also if Dark Matter does not interact with matter how is it that seeded Galaxy formation is thought of as proof IE forming the cosmic web... What would it be that causes matter to follow the same path if not interaction? 5:56
Can the corona virus be the dark matter clump ?
Sooo coooool
its funny how everyone think they scientists in the comments when they didn't conduct 1 experiment in their lives🤣
You be surprised what could cc
Could count as a experiment everyone watching this video probably has done one
One can learn a lot of theory without doing exprriments, just as you can learn a lot about how your car works without being an auto mechanic.
Hmmm, interesting topic.
So first off, you’re telling me dark matter is everywhere. Then you go on telling me that dark matter can be black holes at the beginning of the universe. Then you say that the big bang was infinitesimally small and happened everywhere. Then would it not make sense that the dark matter is the big bang still happening at a really small scale because it’s really really small and it’s everywhere. Don’t take my word for it, I’m just another Joe
Bro 40:00 mr ah over there
Expansion of the universe is not actually acceleration, it's an illusion caused by a gravitational dopplar shift. For the same reason that gravitational lensing happens, gravity distorts the frequency of light emitted from distant galaxies.
Gravity causes a time-space distortion that redshifts its photons throughout their journey to you.
The further away a galaxy is, the more time its photons are distorted at an exponentially reduced value as their distance from the galaxy's gravitational field increases.
Galaxies are much further away than measurements indicate, although they typically aren't accelerating away from you.
Dark energy is an illusion caused by a spacial distortion caused by the gravitational fields of the distant galaxies emitting the light, there is no mysterious energy accelerating galaxies away from you, no dark energy causing acceleration, no unaccounted for dark matter, and certainly, no big bang. This universe is eternal, without beginning or ending. Cosmic background microwaves are but distant galaxies who's light has been gravitationally distorted beyond your visible spectrum.
Since dark matter doesn't exist how do they also look for big foot?
Is it impossible that this is the Æther that Einstein unintentionally proved false? Apologies, newb here with newb questions. :D
This will blow your mind. Find the "About" tab on my channel with info to read and a link, go to the link and click on "created playlists".
@@gameresearch9535 I've only watched 200 or so of those videos/clips... SOO much information... NEED MORE INPUT! STEPHANIE!
Why does matter matter?
It must be great going home from work a failure EVERYDAY!
Could dark matter be the spiritual world??
They may as well look for pixies while they're at it as they're just as real as dark matter!
I like how they explain how to detect dark matter, when we have never detected it. I know, I know. Have to start somewhere. It could be a myth too.
Definitely not a myth lol we already can detect it by observing it's influence. What they mean is other ways of detecting in order to rule out what it isn't, as opposed to revealing what it is.
Dark matter I am 667 just because
envolk that tooth fairy
Can't find something if it doesn't exist. General relativity is incomplete. Einstein and Newton never addressed the action causing gravity in their equations. If they included the action causing gravity they would have predicted the slow acceleration that occurs to solar systems and galaxies. Stars and galaxies accelerate at the same rate regardless of the amount of mass they contain or the distance between.
Gravitation lensing is a mirage because light bends and distorts as it passes through a heated medium, like the corona of the sun or the heated gas between clusters of galaxies that are near one another.
The reason why stars have not reached the escape velocity of galaxies is because the stars in the galaxy accelerate so slow that they are not able to escape. I deduced the acceleration rate of stars and galaxies to be 2.007x10-7 in/s. That is an acceleration rate less than the width of a proton per second. Thus no matter how much speed they build over time they will never reach the velocity to escape the galaxy's gravity.
Dark matter is simply the mistake assuming that gravity is the only force in the universe able to move mass when it is not. Mass and gravity are not causing stars and galaxies throughout the universe to accelerate at 2.007x10-7 in/s. For if gravity was causing the acceleration then the acceleration would always be different for stars and galaxies. But their velocities are clearly the same. Do the math yourself.
The image of the Bullet cluster was done in X-ray, gamma ray and visual light. It does not indicate any dark matter. Assuming so would be grasping for straws and getting forked.
In the same way nuns search for God.. praying.
Key word: "scientists".
@@Ebani Correct
There is no dark matter. It is a misunderstanding caused by the finite speed of light. Read the explanation in a Short Treatise on the Space Time Continuum by Piankh.
Dark Matter matters!
Searching for something that doesn't exist is a waste of time
25 years and billions spend all over to find dark matter. Isn t it time to change the theory??
Which theory?
@@Hookooo I am not an expert. Scientists have noticed that their isn t enough matter to keep galaxies together. They should not stick together due to the speed rotation. So there is dark matter that has been introduced to explain the observation and complete the mass that we can t observe. And in the other hand as we noticed that the expansion of the universe is accelerating we introduced dark energy to explain it. But all over the world there are experiments that try to find neutrinos (particle of dark matter). Nothing has bee. Found yet. There are other scientist that try to find another theory to explain the missing matter and the expansion of the universe. They are just another theory as the negative mass for exemple. My comment was just a call to find another solution to dark matter which is supposed to represent around 70% of the mass of the universe. And sorry it was not meant to criticize or to be negative. Just a call for fresh ideas
Dark matter now is so embedded in the lambdaCDM model of Cosmology that is really a paradigm. If you look at History, you see that a lot of people have to die off before a paradigm changes, no matter its troubles. Another problem is what will sustitute it. I am parcial to MOND, but a convincing relativistic extension is still in the future, there istha CMB data to account to... A messy problem. Time will tell, hopefully.
@@eljcd I absolutely agree. I just regret that there are very few people that try to find another path to darkmatter. And it looks like it is very difficult for many scientists to just be allowed to look in other directions just because as you said it it is too much embedded in the theory...
the problem with mond isn't that "there's no way GR could be wrong", the problem with mond is that it doesn't work. From reddit:
Below is basically a historical approach to why we believe in dark matter. I will also cite this paper for the serious student who wants to read more, or who wants to check my claims agains the literature.
In the early 1930s, a Dutch scientist named Jan Oort originally found that there are objects in galaxies that are moving faster than the escape velocity of the same galaxies (given the observed mass) and concluded there must be unobservable mass holding these objects in and published his theory in 1932.
Evidence 1: Objects in galaxies often move faster than the escape velocities but don't actually escape.
Zwicky, also in the 1930s, found that galaxies have much more kinetic energy than could be explained by the observed mass and concluded there must be some unobserved mass he called dark matter. (Zwicky then coined the term "dark matter")
Evidence 2: Galaxies have more kinetic energy than "normal" matter alone would allow for.
Vera Rubin then decided to study what are known as the 'rotation curves' of galaxies and found this plot. As you can see, the velocity away from the center is very different from what is predicted from the observed matter. She concluded that something like Zwickey's proposed dark matter was needed to explain this.
Evidence 3: Galaxies rotate differently than "normal" matter alone would allow for.
In 1979, D. Walsh et al. were among the first to detect gravitational lensing proposed by relativity. One problem: the amount light that is lensed is much greater than would be expected from the known observable matter. However, if you add the exact amount of dark matter that fixes the rotation curves above, you get the exact amount of expected gravitational lensing.
Evidence 4: Galaxies bend light greater than "normal" matter alone would allow. And the "unseen" amount needed is the exact same amount that resolves 1-3 above.
By this time people were taking dark matter seriously since there were independent ways of verifying the needed mass.
MACHOs were proposed as solutions (which are basically normal stars that are just to faint to see from earth) but recent surveys have ruled this out because as our sensitivity for these objects increase, we don't see any "missing" stars that could explain the issue.
Evidence 5: Our telescopes are orders of magnitude better than in the 30s. And the better we look then more it's confirmed that unseen "normal" matter is never going to solve the problem
The ratio of deuterium to hydrogen in a the present universe is known to be proportional to the density of the universe. The observed ratio in the universe was discovered to be inconsistent with only observed matter... but it was exactly what was predicted if you add the same dark mater to galaxies as the groups did above.
Evidence 6: The deuterium to hydrogen ratio is completely independent of the evidences above and yet confirms the exact same amount of "missing" mass is needed.
The cosmic microwave background's power spectrum is very sensitive to how much matter is in the universe. As this plot shows here, only if the observable matter is ~4% of the total energy budget can the data be explained.
Evidence 7: Independent of all observations of stars and galaxies, light from the big bang also calls for the exact same amount of "missing" mass.
This image may be hard to understand but it turns out that we can quantify the "shape" of how galaxies cluster with and without dark matter. The "splotchiness" of the clustering from these SDSS pictures match the dark matter prediction only.
Evidence 8: Independent of how galaxies rotate, their kinetic energy, etc... is the question of how they cluster together. And observations of clustering confirm the necessity of vats of intermediate dark matter"
One of the recent most convincing things was the bullet cluster as described here. We saw two galaxies collide where the "observed" matter actually underwent a collision but the gravitational lensing kept moving un-impeded which matches the belief that the majority of mass in a galaxy is collisionless dark matter that felt no colliding interaction and passed right on through bringing the bulk of the gravitational lensing with it.
Evidence 9: When galaxies merge, we can literally watch the collisionless dark matter passing through the other side via gravitational lensing.
In 2009, Penny et al. showed that dark matter is required for fast rotating galaxies to not be ripped apart by tidal forces. And of course, the required amount is the exact same as what solves every other problem above.
Evidence 10: Galaxies experience tidal forces that basic physics says should rip them apart and yet they remain stable. And the amount of unseen matter necessary to keep them stable is exactly what is needed for everything else.
There are counter-theories, but as Sean Carroll does nicely here is to show how badly the counter theories work. They don't fit all the data. They are way more messy and complicated. They continue to be falsified by new experiments. Etc...
To the contrary, Zwicky's proposed dark matter model from back in the 1930s continues to both explain and predict everything we observe flawlessly across multiple generations of scientists testing it independently. Hence dark matter is widely believed.
Evidence 11: Dark matter theories have been around for more than 80 years, and not one alternative has ever been able to explain even most of the above. Except the original theory that has predicted it all.
Conclusion: Look, I know people love to express skepticism for dark matter for a whole host of reasons but at the end of the day, the vanilla theories of dark matter have passed literally dozens of tests without fail over many many decades now. Very independent tests across different research groups and generations. So personally I think that we have officially entered a realm where it's important for everyone to be skeptical of the claim that dark matter isn't real. Or the claim that scientists don't know what they are doing.
Also be skeptical when the inevitable media article comes out month after month saying someone has "debunked" dark matter because their theory explains some rotation curve from the 1930s. Skeptical because rotation curves are one of at least a dozen independent tests, not to mention 80 years of solid predictivity.
Why are you screaming it at us lady
Huge waste of money looking for something that doesn't exist.
@lightdark00 no problem. If you just prove your thought, you can save money for all scientists and get a Nobel Prize while you're at it😊
Not to mention... how much $$ is wasted on searching for god?🤣🤣
I’d love to see the paper you wrote that provides evidence for this!
You may be correct that Dark Matter does not exist however there is data on the motions in our galaxy and universe at large that need an explanation, Dark Matter is one hypothesis that if found could explain what we observe within the current framework of our understanding. Perhaps dark matter is just an artifact of current theory. Without the science being done we should not know.
@@woodstockjon420 : A devil's advocate would point out the difference between spending tax dollars searching for dark matter versus spending private dollars "searching" (philosophizing?) for God. (A devil's advocate might also recommend wasting a lot more dollars.) It's unknown whether the search to understand dark matter will ever deliver any practical public benefits (beyond peace of mind for a few thousand physicists and cosmologists) but presumably there's a chance it will someday deliver major benefits. (Assuming the vast bulk of humanity doesn't first get enslaved by weaponized advances in neuroscience research).