The long and short of this lecture, like every other talk about Dark Matter, seems to be we are still in the dark about the matter.

"We know dark matter exists by the way the universe is shaped." ...Which we don't actually KNOW at all, but have calculated mathematically and also built a whole mathematical framework to support, and if that's wrong, well, we know nothing. We made our equations agree with each other and input variables we can't explain to make them come out right. Proof! Great science there.

Yes the trumpet shaped Universe, the big band theory.

The missing mass is dilated mass. We have all heard the phrase "mass becomes infinite at the speed of light" this phenomenon is illustrated in a common relativity graph with velocity (from stationary to the speed of light) on the horizontal line and dilation (sometimes called gamma or y) on the vertical line. Mass that is dilated is smeared through spacetime relative to an outside/stationary/Earthbound observer. Wherever you have an astronomical quantity of mass, dilation will occur because high mass means high momentum. There is no place in the universe where mass is more concentrated than at the center of a galaxy. In the 1939 journal "Annals of Mathematics" Einstein wrote about dilation occurring in regions that would have less mass than that which would exist at the center of common spiral galaxies. Therefore it is safe to say that according to Einstein's math the mass at the center of our own galaxy must be dilated, in other words that mass is all around us. It was recently discovered that low mass galaxies (like NGC 1052-DF2) have normal star rotation rates. This is what relativity would predict because there is an insufficient quantity of mass at the center to achieve relativistic velocities. A simple way to confirm this would be to calculate the star rotation rates of a large number of galaxies. This would show that all the high mass galaxies would have star rotation rates that seem to defy the known laws of physics and all the low mass galaxies would have predictable star rotation rates.

I have long found, I get as much understanding out of reading many of the comments, as I do from the lecture itself. The questions raised are answered by other watchers, or the presenter, and they typically are questions beyond and outside of the direct aspects of the lecture. This is certainly true regarding this lecture. Thanks!

Great talk! Thank you!

I can’t believe he’s written a book on something which almost certainly doesn’t exist, some people have spent a career on it.

Thank you sir.

56 minutes to say "we don't know"

"we know dark matter exists because all our suppositions and theories about how the universe works can't possibly be wrong."

Fascinating thankyou

This video was worth spending an hour. Very informative indeed.

That's honestly super interesting

Whilst true that most of this is already available in many other lectures with the only addition being some unique speculation by the speaker we should see it as a good thing! Keeping it in the mouths of the scientific community keeps the research alive!

Takes me back to a maths lecturer I had who couldn't make eye contact...

I think you should please explain and discuss the findings of Subid Sarkar's team. Thank you very much!

Coming at this as a layperson, I find it fascinating that the fact dark matter forms a halo suggests it acts like a field; perhaps even the "donut," if you will, to the "donuthole" of the galactic matter that the former flattens or locks together gravitationally. I often wonder if the supermassive and other black holes might create this halo by some quantum or other effect. Questions I have include: How are we sure dark matter is even present WITHIN our galaxy? Do we see absolutely NO hesitation before galaxies collide that might reveal dark matter? If not for dark matter, would stars near the edge of galaxies simply fly away moving at 220km/s? And would the universe then be more uniform (chaotic) with rogue stars and planets? What part of a spiral galaxy still remain in that case? About a half? A third? 3/4?

thank you for the lecture

"Information is information, not matter or energy. No materialism, which does not admit this, can survive at the present day" by Norbert Wiener, the Father of Cybernetics. If physics wish to survive, than have to recognize the same ontological status of Information, Matter and Energy. That is a key for paving the way to new physics. Because of the fact that physics treats the information as just an artifact of interaction of matter and energy, even at quantum level - no way to detect Dark Matter. Physics should embrace the idea that information can play also a cause role, not only as an effect's one. Thanks for nice and instrumental talk - very interesting.

Humanity needs a major breakthrough in particle / Quantum physics. I know it is a marathon, not entirely under control...but without a major breakthrough, the knowledge and this branch of science are becoming stagnant. To be clear, I am not undermining the objectives of countless physicists, and scientists working in the field. I hope we find a major breakthrough soon.

Dark matter is a hypothesis which allows a mathematical description of "local" anomalies in the fabric of space-time. Dark energy allows a description of the observed anomaly of accelerating cosmic expansion. Both hypotheses require a total of 20 times more stuff than the observable universe to fudge a correspondence between observation and theory. New physics is needed, but I don't know what it would look like.

I ain't a scientist and was looking for something more on black matter but came across this. I found it interesting and thanks for the video. Merry Christmas from Canada

Just throwing out an idea here: we're told that large bodies create gravity by 'bending' space-time, like a bowling ball on rubber sheet, to use a common analogy. Maybe the reason the galaxies spin the way they do is because, instead of bending, the fabric of space-time itself is spinning like an enormous disc, carrying the stars and galaxy with it. That's why they all move at the same speed. I fully expect any half-way competent astrophysicist to explain why I'm wrong. I'd appreciate the lesson.

At 3:16 Dr.Fisher refers to the expansion of the universe as acceleration, several times,which took me a while to tease out what he was actually saying. Kind of cast a pall over the rest of the lecture

Gravity Defined: Gravity can be defined as the Electromagnetic force that matter excerpts on the Universe, on Dark energy, that causes a "Dark Energy Field Effect" or "Gravity"

Three scientific lines without dark substances - 1. "First test of Verlinde's theory of Emergent Gravity using Weak Gravitational Lensing measurements" "Understanding galaxy rotation curves with Verlinde's emergent gravity" 2. "Testing the Strong Equivalence Principle: Detection of the External Field Effect in Rotationally Supported Galaxies" 3. "Galactic rotation curve and dark matter according to gravitomagnetism"

We always see the graphics of mass warping a space time grid. What if when extremely massive objects (galaxies, black holes, etc) warp space time, it doesn’t just pop back to “neutral” when they move on? If it left a trail, something like a ditch on the space time grid graphic, wouldn’t gravitational effects still be observed? I don’t even know if this makes sense mathematically, I just like to brainstorm.

Was the heavy neutrino experiment Mr. Fisher talked about the same as the hypothetical sterile neutrinos?

This picture seems to suggest that matter is reducing over time (into black holes) and the vacuum energy or the space between matter and things is expanding - the less matter of both kinds, the bigger the vacuum thus increasing that vacuum energy and the expansion

The real story starts at 30:20 .

Dark matter is a theory to explain another theory they’re having trouble to explain.

21:30 "this is a great screensaver" This is a great screen destroyer, do you not remeber why we had screen savers?

Existential Physics: Do all galaxies eventually collapse in upon themselves? Modern science claims that 'gravity' is matter bending the fabric of spacetime. There is a lot of matter in a galaxy which would make a huge dent in spacetime. How could galaxies not eventually collapse in upon themselves if spacetime were bent to make it so? (Or is modern science wrong about 'gravity', 'space', and/or 'time'?)

Perhaps because we cannot still quantify dark matter with the standard model, we may have to find another field of matter in the space/time metric from which we can propose a dark matter particle related to but not included in the standard model. Just a thought.

“We know that dark matter exists.” LOLno. We know that some observations don’t match what we expect from certain physical models. That doesn’t mean we should go drawing epicycles.

how do we rule out a modification of the gravity equations

A fascinating talk - thank you. As dark matter is proving so elusive, is the notion of Modified Newtonian Dynamics - MOND- becoming a viable option? And as an aside, is the model ship behind you the Titanic? Lets hope the standard model proves more unsinkable !

what these thinkers always fail to explain is that dark matter and dark energy are theoretical notions, which have not been observed and are not consistent with all observable date - but dark matter does exist as a subject to talk about to support a career to pay mortgage and get the kids through school.

TLDR: Dark matter is a theoretical magical matter that was invented over 100 years ago by some guy who applied newtons law while looking at a galaxy and realized that the outer most objects were not spinning around the galactic center as slow as orbital mechanics dictated. They did move at the right speed if the guy toke into account that the galaxy was heavier then he estimated the weight to be at. To him, fudging the numbers to get the right answer meant that the problem was that he was not seeing the missing matter instead of assuming the math to be wrong. Because maths in a era they had not gone to the moon yes was obviously not flawed, he theorized that there is somehow a dark, invisible form of matter. Modern dark matter believers say that over 70% of the universe matter is dark matter, how every they are not able to detect or prove that it exist. In essence dark matter is the modern version of "i dont understand lighting, therefore it is god who is angry". Currently there is a lot of scientist who are working with models to fix the equation that we use for gravity. In essence fixing the math instead of inventing something that clearly does not exist. Turns out, most of these works require just a minute adjustment, Sadly, the belief in dark matter which goes against the scientific principle is so encrusted now that to prove the dark matter believers wrong, their mathematical formula has to essentially also account for all the dumb shit they also say is the work of dark matter which is ridiculous since they basically have to prove the earth is round and as far as we know also show that the same proof explains why the mitochondria is the powerhouse of the cell, too things that as far as we know are unrelated except they have no proof. Basicaly, Dark matter believes are religious extremist with no proof for anything because its all theoretical since we are stuck on this planet.

Last years Nobel prize in physics was won by three physicists who proved that quantum entanglement effects are instant or faster than light across vast distances meaning it’s possible that aliens are communicating with quantum entanglement which possibly has the added advantage/disadvantage that not only will the receiver know the question before he’s received the question but the transmitter will know the answer before he’s sent the question.

The understanding of the presence of Dark Energy and Dark Matter can be found in: "Atomic Gravity" International Journal of Physics.

If dark matter can polarize light through gravity, then could our sun's light that reaches earth be effected by having different polarization, would the earth heat up or cool down? I know someone did a study on solar panels about using polarized light .

if the expansion of the galaxy is counteracted by gravity, so we're not getting bigger, what would happen if you were just floating between galaxies? would you expand?

Thank you for the presentation. Question: By when will we be able to use dark matter and especially dark energy for our daily needs?

Speed of light being fixed is an assumption that holds in the near space around us. Assumptions are not always valid.

I greatly enjoyed your descriptions of your work. This dark matter and energy stuff - well - I think we need to remain skeptical. Last year I read an article by an E. European scientist who claims dark matter clearly doesn't exist. For dark matter, he argues, to "work" - to explain galactic rotation - it has to be a sort of donut structure outside our galaxy. But, this scientist maintains, almost everyone in physics ignores the obvious problem, that small galaxies or clusters orbit galaxies where this donut of dark matter is supposed to be. And these small galaxies or clusters are NOT impacted by this supposed dark matter. So dark matter can't exist. Well, that's one argument. MOND is looking better and better. There is a great chance that Dark Matter isn't real - doesn't exist. Dark Energy may also not exist. The universe may not be expanding in an accelerated sense. The so-called acceleration we seem to detect may be related to the idea that "uniformity" or "sameness" - that our assumptions about how this works in space were wrong. That you need a much, much bigger region of space before uniformity is real. We have detected structures that definitely throw off our old data, which was used to guesstimate uniformity of space. If space is not uniform at the vast region we thought it was, then some of the galactic redshif/blueshift we detect may be caused by something much simpler than "dark energy". Dark energy - and acceleration of expansion - may very well be myths/errors. There is a prominent physicist at Oxford, iirc, advocating what I'm saying."" Super symmetry has suffered a number of serious disappointments in the past 10 or so years. I don't want to sound disrespectful, but Dark Energy and Dark Matter are under serious attack in academia. There are strong reasons to believe these are flawed theories.

I was reading an article that brought up something I found to be interesting...in that it was a new-ish idea and not yet disproven. The 2nd law of infodynamics I believe it was called. It was posited that the universe contains a ton of information, what if information has a weight (even if infinestimal) and that's what constitutes dark matter. Again, I found it to be interesting. Could information have a weight?

I still don't understand what is dark matter after attending this lecture.

Great video. But I get a bit concerned when I hear scientist say we know all there is to know about what makes up the universe when we are still discovering stuff even in the last 20 years. Need to be a bit more humble and then we might actually move the unexplained area forward. One of the areas that I dont understand is that if the universe itself is expanding, why is is natural to try to associate that with a regular force in the same way as a force that occurs in regular matter. There is fabric and then is the content. different things..

The particle mass seems to be a mathematical solution for something like Andromeda data, but they never give the math of the first 500M years and galaxy formation from maybe a sphere 100 time the galaxies eventual size with very very weak initial gravitational attraction. You turn on a switch and the dark matter makes a quick trip 100 times the size of the galaxy in 500M years, then the switch is turned off and parks in position to make the Andromeda calculations work for the next 5, 10, 100 billion years with maybe a massive black hole pulling on it at a much closer distance than that original 300M years. It doesn't make sense that it would move so fast to a very weak gravitational force and sit in some theoretical perfect position thereafter.

Did i miss the answer ? I still don’t know what dark matter is, i know what it isn’t

Dark matter = we have no idea wtf it is... Update today = we still have no idea wtf it is.. until next time. Brought to you by experts you have to trust.

Linier expansion early on, then polynomial :) Interesting

Seems no surprise that the past is getting further away faster in order to prevent time travel and all the complex paradoxes that would create. It's a natural barrier to stop us screwing with the past.

I like his point on the time between Newton and Einstein .... Don't expect any new events here on this subject till another real genius is on the scene.

Perhaps gravity isn’t as much of a monopole after all.

Once two galaxies' Halo's have significantly begun to merge what is the probability that the two galaxies' will fully merge? Is the bullet cluster going to regroup into the dark matter or will a significant portion of each galaxy continue on and escape the dark matter in the middle?

It seems at times as though "dark energy" is simply code for the mystery of how space itself expands. Space grows and is warped by mass. Space is rather more "thing like" than one would ever have guessed.

is dark matter as defined by it's gravitational properties evident in the rotational velocities of stars very near the event horizon of a black hole?

Dark matter and energy are placeholders for "that yet to be discovered'.

Could anyone enlighten me, “ghost” particles are emitted from all stars, and the shear numbers emitted are beyond comprehension, where do these particles end up in the fabric of space, one assume’s that these tiny neutrinos have mass so given their numbers over time will cause gravitational effects, since the birth of the very first stars the number of neutrino’s must be colossal plus I wonder if neutrino’s are recycled in any way or do they simply exist as massive ash heaps (so to speak) between the stars and the galaxies.

not really understanding this "expanding image" shouldn't be going 720 degrees in every direction?

What if our universe is "just" another form of black hole, and both the expansion we observe, the background radiation, and the regions of more and less clustered areas that are attributed to dark matter are all just the effect of the internal fabric of our universe being twisted and crumpled under extreme forces that we don't observe because of our frame of reference? That there is no dark matter or actual expansion, only corruption of the laws of physics caused by us being inside a black hole like extreme event inside another universe? These are just shower thoughts, but it would make sense and be coherent with everything I know about astronomical phenomena

If you've seen one lecture on dark matter, you've seen them all.

There are other fields of force that need to be in place that interact with dark matter.

If dark matter has mass, it does interact with at least the Higgs, right?

You don't know dark matter exists because of the way things are shaped in our universe, you know there is an extra gravitational effect, you then make a rational presupposition (the bane of Science), & conclude it's because of some type of extra matter, I've come up with five hypotheses that don't require it, relative mass caused by dark energy, probability mass of the quantum wave-functions, nested gravity wells or contextual gravity, ambient mass of the photonic & phononic energy coming into our Galaxy from outside of it & curvature differentials between the negatively curved galactic space-time & the positively curved intergalactic space-time, it's tufted space-time.

Working on the fundamental question how universe is created and is working since its creation is a tribute man pays for immense favours showered on him by the creator. I salute you and the people like you who selflessly spend their days and nights hunting for truth. Thank you very much sir.

Based on our limited knowledge of this subject, is it possible that the "Stuff we know about" and dark matter is 50/50 with dark energy? Entangled pairs could be split into matter and energy.

Fantastic talk

This is utterly in watchable. This guy is just maddening to listen to… I made it to about halfway before giving up

I may be a bit OCD, but as I'm trying to listen to your talk, that model behind you is bugging me. Smoke didn't come out of the fourth stack from the boilers (maybe a bit from the kitchen and smokers lounge, which wouldn't have been visible). Could the amounts of matter between stars be, underestimated? Our star (and the planets) have cleared the local area of stray molecules, but could interstellar space have more than we have estimated in our calculations?

I though the blue parts on the cmb were the denser parts

At 20 seconds: We don't know what dark matter actually is but my book.....? Nuf said.

I think it's more likely that there's not this invisible magic stuff but it's just a lack of understanding of how things work over long distances.

The search for Dark Matter is likely to end up like the search for Phlogiston or the Luminiferous Aether.

I'm pretty sure dark matter isn't some quantum thing. I think it's a more primordial information state intermediate to dark energy and quantum field related information. Also it is mostly a relic/initiator of the process that created the inflationary transition in the first place...

18min in, I'm daydreaming, but what if dark energy/matter are like a sort of ocean, a form of matter that reacts in a similar way to water, as in well we're floating in something we don't understand, like a gas or a liquid. So then I wondered, isn't Hydrogen a funky particle, Hydrogen bonding is a big deal here on earth at least. Perhaps there is something more to hydrogen that we are unable to comprehend just yet with our current technology.

We know a huge amount about what dark matter does and where it is, and a great deal about what it isn't, but its microscopic properties are a complete mystery! If you're a physicist these days, then this is reason to be both frustrated (because of the lack of positive data) and creative (since there is a great deal of freedom to theorize). It's an interesting time

E=MC2? The energy, includes? Do you acknowledge the electric universe and plasma? If not you might get your pie graph.

Dark Energy and Dark Matter May Be Anti Gravity. This drawing makes a case for anti gravity, not gravity, as the force that comes from acceleration.

An astrophysicist needs to invent a new type of maths which models three dimensional space with numerous mass gravity warps over time and then run the maths on a supercomputer which I believe may show the accumulation of gravity warps bends space outwards causing galaxies to move away from each other. It may be necessary to begin with star clusters which mysteriously seem to lose stars and drift apart. The constellation Ursa Major, the Great Bear, is an opened star cluster, all it’s stars are the same age and with similar chemistry, so what made a star cluster fly apart? surely they should spend eternity in each other’s orbits with perhaps one or two stars being hurled out resulting in the cluster tightening but that’s not what has happened, the stars are flying apart. This is where to find the answers to why galaxies are moving apart.

What if Dark Matter is on a nearby brane, but not the brane we're on composed of length, width, height and time? The string/brane guys say gravity can leak from one brane to another. So you can't find Dark Matter by searching through our brane using experimental apparatus. We actually would need to go somewhere else that had either more dimensions or different dimensions to find it.

What is the universe expanding into?

It seems to be remarkably smooth on the galaxy chart (34:30) - it has me wonder what the density gradient to distance from the center is... Does it follow the square law, where double the distance equal a 4th the gravity? Or something else? Because - imagine a nearly 0 interacting particle making orbits in that cloud. Probably very light, lots of dark matter particles, and also traveling very fast. That cloud size must narrow down the posibilities for the mass of dark matter, right?

we know dark matter exists because of the shape of things , OR we need to have a theory of Compound linked Gravity fields

the question is: what is dark physics? It seem to be devolving into mathematicians scrawling reams of formulas that very few understand. Many tap out ti infinities that are “renormalized”.

Maybe inflation happens faster as you get away from the blackhole. The rate of inflation keeps the star systems moving at a faster pace the further they get from the galaxy. This is how galaxy systems are kept stable inspite of the gravitational and inflationary forces. How exactly do black holes interfere with the process of inflation?

It would be exremley interesting if it is a text in english languagae to the video. I am swedish and understand much better written english than a lot of strange dialects!

Very interesting stuff. However all the math falls apart at the point of origin so the big bang is not proven. It's still a theory, not a law. And the fact we can only account for 4% of energy/matter/gravitational forces suggests that we know so very little still about all the laws, forces, and particles at work in the Universe. We simply have a lot to learn and discover still.

There is no dark matter, the reason why the stars in the arm of the galaxy are all traveling at the same speed is because they are travelling in a straight line , linear path. .. The arm appears curved due to the gravitational lens effect. The second arm is a reflection due to gravitational mirroring from the gravitational lens. If the arm of stars were rotating then their speeds would increase towards the outside edge, but they do not. All the stars travel at the same speed, as if in a straight line. .. The influence on the stars positions is optically perceptual, from gravity lensing, and mirroring, and not physically gravitational. .. i.e. our galaxy is really just a comet shaped line of stars, swimming into a curvature of space, that lenses and mirrors... That curvature of space may be a source of great power... I think it's important for us to try to work out exactly what we are looking at when we look out into space. The gravitational curvature may have the power to gravitationally sling shot a craft to huge speeds, much more so than the weaker gravity of a planet .. Also there may be much to be learnt from studying the intense power of curved space... In short, ,, in my opinion,,,Dark matter doesn't exist, it's just an absence of straight space...

It's very simple

Occam's razor I think we are just wrong about the masslessness of photons and we are trying to find the mass of a spec of dust on a home bathroom scale we need too a better tool before we can find is tiny tiny tiny mass. Super ironic name for it if true

SOUND?

We observe from a tiny point in an obscure part of our galaxy, and fill in blanks with magic.

Reworked either theory . It's something for hard heads who will do anything but consider the bubble tension is telling us expansion is telling us to reform.

Missing mass? Something that should be there but can not be uncovered? What changes if the speed of light is not a constant? Can you really age the universe by Doppler shift of light? Of course there are things we can not see, consistent in our reality; The air we breathe, the forces of gravity, magnetism, electricity, and more. Physics is the study of properties of matter. Can we uncover dark properties of our universe?

I have heard that there are at least a couple of galaxies that appear to have no dark matter. If this is the case, then it seems to me that perhaps ironically these galaxies seemed to disprove theories such as MOND because surely gravitational laws should be consistent across all galaxies?

I wish I knew math as good as Mr. Steven Weinberg

I probably sound like an idiot, but I can't stop wondering if not only mass, but also energy has gravity. If e=mc^2 and F= G(m1*m2/r^2) then by combining these two equations, can't we conclude that not only mass, but also energy should have gravity? As such, the speed of the rotation of galaxies which need more gravity to explain is in itself energy and if we can conclude that energy also has gravity, then we may find our solution to where the gravity is coming from is the energy from the motion which we are trying to explain, as well as the temperature of the galaxy, etc. I'm not very well educated in this field, so be kind :)