21 Subatomic Stories: What mysteries might dark matter solve?
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- čas přidán 22. 05. 2024
- There are mysteries in the cosmos that general relativity can’t explain, things like how galaxies rotate and how clusters of galaxies move. Scientists have ideas as to possible explanations. In this episode of Subatomic Stories, Fermilab’s Dr. Don Lincoln lists some of the most pressing mysteries. In the next episode, he’ll talk about the quest for solutions.
Natural nuclear reactor in Africa
www.iaea.org/newscenter/news/...
Are supernovae or neutron star collisions the origin of heavy elements?www.quantamagazine.org/did-ne...
Complex dark matter long form video
• Complex Dark Matter
Scientific American article on complex dark matter (paywall)
www.scientificamerican.com/ar...
Fermilab physics 101:
www.fnal.gov/pub/science/part...
Fermilab home page:
fnal.gov
Wu experiment schematic credit:
Pen88, with English translation by Stigmatella aurantiaca
Neutron star animation credit:
ESO/L. Calçada. Music: Johan B. Monell (www.johanmonell.com) - Věda a technologie
I love how nicely Dr. Don Lincoln explains physics, he should get a Nobel prize form us! :)
Or rather say people's prize
Nobel Prize is mostly political/bigotry. As you see by his choices two incredible women didn’t get prizes because of these reasons. I’m not a liberal feminist but their contributions should be recognized by us common folk as well as many others. Simply we need more young people to read more history and deeply appreciate the incredible accomplishments of our giants who’s shoulders we all stand upon.
@@john-paulsilke893 I agree. It is not just about gender bias, but political too. For example Mahatma Gandhi did not get Nobel.
But good news is, Dr. Don Lincoln has won the greatest prize of humanity: our hearts! :)
Navin Singh yes it’s not the greatest “prize” and has a nasty history. But it does still represent a tremendous accomplishment. (Not the Nobel Peace Prize, that’s complete BS). Obviously like everything it’s complicated.
@@john-paulsilke893 A Nobel Prize is still pretty impressive, even if the selection process isn't perfect. Its not like those awarded it weren't very good. And the selection process is probably better now than 50-70 years ago.
You may or may not have earned yourself a Nobel for physics Dr. Lincoln. I am not qualified to judge, but, I can say that if they gave out Nobel's for educating people about physics, you would definitely have earned one. Thank you!
This series is an amazing rundown of physics topics. I can imagine showing it to someone not at all interested in physics to get them hooked.
For some reason I just can’t stop listening to your lectures. Great job, thanks!
Hi, Dr. Lincoln. Thank you so much for teaching us about two great physicists who don't seem to get much attention: Rubin and Wu.
After a few weeks, I have finally caught up! Thank you so much for this series! I hope you continue it until a Theory of Everything is found!
Dr. Lincoln rocks! Those videos are extremely good at making you want to know more about the subject! Thanks!
It been some years now and this guy blows all youtubers out of the water. All I know is I need a cup of coffee and some tobacco to listen and I don't have that all the time. But he is efficient and explain things with ease it seems. So if you wonder this is the go to channel. Now, where are the 200 youtube clips about other things I am supposed to watch.
Question: Dr. Lincoln, I understand that heavier elements are unstable because each proton experiences electromagnetic repulsion from all other protons but only experiences strong force attraction from adjacent protons and neutrons. That being the case, why can't we make heavier elements more stable by adding more neutrons to make the protons further apart? Is there some other mechanism, perhaps the weak force, that causes these high neutron isotopes to decay more rapidly as you add neutrons?
Edit: Thank you for all of your responses. I'm also looking forward to see what Dr. Lincoln has to say about it.
Its not just the electrostatic repulsion. Yes the weak force plays a big role. In the end, if a decay path to a lower energy state exists, then, sooner or later, the nucleus will experience radioactive decay.
That's why Tritium is unstable, but Helium3 is stable.
Here are my thoughts from a high school frame:
The neutrons are almost the same size as protons, so unless you add too many neutrons, you won't make a difference.
And if you add too many neutrons, you make it unstable and susceptible to decay.
Any corrections would be highly appreciated.
Rijul and the other Michael are both correct. To add a tiny bit more detail, the nucleus is not just sitting there, it is a very dynamic place. Protons and neutrons move all over the place, and the shape of the nucleus changes constantly. Look for "liquid drop nucleus model" if you want to see pictures and animations. The nucleus can come into configurations where it is separated into two blobs with a relatively thin area connecting them, so then it is not hard to push it over the edge and see it split. Those dynamics also help neutrons to decay via the weak force. While they are safely within the nucleus they don't decay very often, but in some configurations they have more energy and can decay more easily. It is a great question, and I'd love to hear Dr Lincoln's explanation :)
@@michaeldamolsen oh I didn't know that. Thanks.
Part of this is a fundamental problem, but another part is just a technical problem:
1) Larger nuclei do have more neutrons-per-proton: en.wikipedia.org/wiki/Valley_of_stability. This protects them from beta-decay, proton-drip, and neutron-drip; however, large enough nuclei do still decay by alpha decay, spontaneous fission, and cluster-decay, which become progressively more common as the number of particles in a nucleus goes up. Alpha-decay is the first main reason why the "valley of stability" ends after a certain point. I don't really understand the mechanism, but it might help to consider that, barring beta-decay, which is charged-current weak interaction, nuclei decay by quantum tunneling, i.e., the positions and velocities of particles randomly ends up being enough to eject individual protons or neutrons (proton or neutron emission or "drip"), or clusters of protons and neutrons (alpha-decay, cluster-decay, spontaneous fission). Also, the protons and neutrons are both "fermions" with spin=1/2, and so obey the Pauli exclusion principle, just like electrons. (The same spin means they even can only have 2 protons or 2 neutrons per "orbital", unlike spin=3/2 particles, which could have 4. Protons and neutrons occupy completely different "orbitals", though.) This means that adding more protons or neutrons requires them to enter higher and higher energy-states, which have higher average momenta: en.wikipedia.org/wiki/Nuclear_shell_model This is presumably why binding-energy goes up with mass. I can see how this might make it more likely for the positions and momenta of the particles to eventually randomly align into separate groups that aren't touching each other and which have high enough relative momenta to escape each other, especially since more nuclei might make this statistically more likely.
In that vein of thinking, you might consider that there is a conjecture that many more nuclei than we realize, perhaps including all nuclei heavier than Iron-56, do eventually decay into lower-energy nuclei, but that this process is so ridiculously slow that we have never observed it for "observationally stable" nuclei. (It's also possible that any mass of lighter atoms would eventually spontaneously fuse by quantum tunneling to reduce internal energy and emit it as radiation, increasing entropy, turning rogue planets, etc. into "iron stars" in a universe long after astrophysical black-holes evaporated by Hawking radiation, and it's even possible that protons themselves might decay, and/or that all normal matter might eventually decay into some more stable state like strange matter might be.) We do periodically detect decays from nuclei that had never been detected to decay before: For one example, bismuth used to be considered to have 1 stable isotope, but then it was discovered in 2003 that that it alpha-decayed with a 19 quintillion year half-life; for another example, the XENON1T detector attempted to to detect dark matter using an underground tank of xenon-124 that was supposed to be more sensitive than any other device made to minute non-gravitational interactions that novel particles might have, and this last year ended up discovering that xenon-124 decays by double electron capture with an 18 sextillion year half-life.
2) If you look at a chart of known nuclides with half-life noted by color, you will notice that the "valley stability" seems to quickly die off around polonium to actinium, with astatine's longest-lived isotope having a half-life of 8.1 hours, but then it partially comes back around thorium to plutonium, with thorium and uranium occurring naturally on Earth and with thorium-232 having a 14 billion year half-life, similar to the age of the universe as we know it. (Interestingly, this doesn't really show up in a chart of binding energy, so it must be mostly about increased BARRIERS to decaying, rather than the actual thermodynamic favorability of doing so.) You might mix metaphors and call this return of the "valley of stability" an "island of stability" on the chart. The term "island of stability", however, is generally used to refer to further regions of partial stability later on along the continuation of the "valley", which have been predicted but not yet observed: en.wikipedia.org/wiki/Island_of_stability These are predicted to be regions in the chart where barriers to spontaneous fission, alpha decay, and cluster-decay will all be high, leading to longer half-lives than the surrounding nuclides in the chart.
The next "island of stability" predicted by most current theoretical models actually lies in the range of elements that have already been made - specifically, somewhere in the vicinity of flerovium-298, since that has 114 protons and 184 neutrons, which are both predicted by modern models to be "magic numbers" where proton and neutron shells fill up, somewhat similar to how noble gasses are chemically stable due to having full electron shells. The problem is that we don't have a good way to make nuclides with that many neutrons yet: the highest neutron-count isotope of flerovium ever made was either flerovium-290 or flerovium-289, depending on which observations were actually real. Part of the reason why it's so hard to create nuclides with so many neutrons becomes apparent when you look back at the "valley of stability": Smaller nuclei that are even remotely stable have less neutrons per proton than larger nuclei that are even remotely stable; thus, smashing together two smaller stable nuclei that are stable enough to actually do this with will pretty much always result in the heavier combined nucleus being neutron-poor for it's size, and thus less stable.
In principle, one of these nuclei could decay by proton-emission or beta-decay, which could make it possible to produce by fusion proton-rich nuclei that would follow a decay-chain that would lead them to a point on the "valley of stability" - perhaps an "island of stability" in the case of superheavy nuclides. In fact, this does happen frequently with smaller nuclides: for example, two protons fuse together to form the ridiculously proton-rich "helium-2" (i.e., 2 protons close to each other), which then occasionally beta-decays decays into deuterium (hydrogen-2) in the tiny amount of time before it falls apart. This is the first step in the P-P Chain which is the main power source for the sun and smaller-mass main-sequence stars (but not for much larger stars, where more energy comes from the CNO-Cycle or Triple-Alpha-Process, the former of which also involves proton-capture followed by beta-decay onto the "valley"). Unfortunately, no such decay path leading to any "island of stability" has yet been found among the superheavy nuclides, which mostly all decay via either spontaneous fission or alpha decay, both of which take away neutrons as well as protons.
One other potential way to get superheavy nuclides you might suggest would be to go the other way and simply shoot lots and lots of neutrons at them and let them decay onto the valley from the other side. This is how it is possible to make relatively large amounts of elements up to einsteinium(Z=99), however, this ends up running into the same problem as making proton-rich nuclei: neutron-rich isotopes of fermium(Z=100) all decay via spontaneous fission or alpha-decay, which the most neutron rich do long before they could ever be hit by another neutron. The short half-life problem, with things decaying long before they can be hit by another neutron with any neutron source we're remotely capable of making would presumably only get worse with higher nuclides, though I don't really know. (Neutron star collisions would create high enough neutron fluxes, though, which is why there is a possibility that they make some superheavy nuclides we can't, maybe even ones on "islands of stability", as one of the questions in the video may have been trying to ask. Even islands of "stability" would probably not contain nuclides stable enough to still be detectable on solar-system bodies, so our lack of detection of them doesn't rule this out. As far as I know, strontium is the only really heavy element that has been spectrally confirmed to have come out of the single gravity-wave-confirmed neutron-star collision to be electromagnetically detected, and theoretical models of electron orbitals in superheavy atoms that have never been made aren't necessarily good enough to detect tiny amounts of them in the cloud produced by such an event, even if they did have relatively long half-lives and we had already managed to sort out the effects of all the smaller nuclei and of thermal radiation, molecular orbitals, vibrations, and rotations, observational noise, etc. in the spectrum.)
One thing that occurs to me is that maybe they could try mixing neutron-fluxes with fluxes of proton-rich particles in some way, but this would probably still have a lot of problems and would likely require ridiculously intense fluxes for any superheavy nuclides to receive both before decaying. The point is, though, that people are working on this problem and just haven't managed to make nuclides in any predicted "island of stability" to test the theories yet.
My favorite science channel
Hello Dr. Lincoln, I am catching up on the Subatomic Stories. Some episodes back you were asked whom you would award two Nobel Prizes to and you chose Vera Rubin and Chien-Shiung Wu. I´d like to add another brilliant physicist: Lise Meitner for the discovery of nuclear fission, but only Otto Hahn had been on the ticket for the Nobel Prize in 1944
Sure. But they asked for two. In my examples, the women were the leaders.
Thank you so much for your awsome video's for all those who are involved in the process.
Thanks Don (if I may be so casual) Another excellent and informative video.
Such an epic series.
Good Morning Dr. Lincoln. You are an amazing and great person.
I have two questions. I recently watched a physics program on cable
where I heard something like this -- "Why is there something instead
of nothing? In the beginning there was ZERO but even ZERO is unstable
and because ZERO is unstable bubble forms." So my questions are -
what does it mean that ZERO is unstable and why do we have probably
"multiverse" instead of nothing or at least our universe instead of nothing.
Thank You very much.
I love this series! You can tell Don likes to answer questions haha
Thank you. This series of videos is excellent.
Well explained..thanx
Enjoyed this very much, thank you.
Thanks for the great video don!
Your videos are just epic. You simply explain quantum principles. Thank you!!
Dr. Lincoln, I once worked at HUHEPL. You bring clarity to the many. Lay on.
Thank you for your amazing content
Amazingly Awesome Video
Dark matter is like my hopes and dreams, invisible.
THANK YOU... PROFESSOR LINCOLN...!!!
Awesome editing.
Hello Dr. Don. Thank you for your answer.
I would also be extremely interested to hear you talk about the shape of the nucleus and its inner structure, a hypothetical island of stability for super heavy elements!
love that you point out how women in STEM have been sleighted by the nobel organization. love you
In all fairness, there are also men who deserved Nobels who didn't get them. But there is no question that a combination of society and the Nobel committee has overlooked female contributions to the advancement of science. At least things are slowly getting better.
DrDon
that's fair :)
Always a pleasant surprise to hear a reference to a researcher at my alma mater. I'll have to read up on Stacy McGaugh's work some more. Looking forward to your videos on some of these explanations!
nice 'stash bro... good book collection you got there too...
Wonderful thankyou !
I like your Nobel Prize award wishes.
. . . and I like the way you think about wanting to see the Sun become a red giant.
Thanks for mentioning Wu. It means a lot
Brilliant picks for a posthumous Nobel, even if they were a bit obvious for fans of Fermilab and the Good Doctor Don.
I think that Rudolf Christian Karl Diesel deserves one. He, more than any other I can think of, except maybe Tesla and Edison, made something that radically changed the world and improved the lives of many millions of people.
The picture at 0:58 deserves a caption. “Zwicky calmly explaining a point of zero controversy, no personal stakes, and purely academic interest.” There ya go.
I've always wondered why dark matter doesn't form its own version of stars, planets, black holes, etc. Thanks for the explanation.
Side note: wouldn't it be neat if it did? I wonder what a "dark matter star" would look like...
It's possible dark matter is more than one thing, so your hopes might still be possible
One would expect clumped dark matter to attract clumped normal matter and vice versa -- both forming coincident objects and objects orbiting invisible companions that are nevertheless not black holes.
@@Lucius_Chiaraviglio this is what i am wondering about ever since i learned about dark matter. shouldn't we see it mixed into "normal" stars, dark matter planets (or clouds, if they don't clump) modifying orbits of other planets etc.
If it did it would be so cool.
We could have a parallel earth made of dark matter, and we would never know about it. All we would know is its gravity, so we might conclude there's a lot of heavy metals in our core.
But otherwise a dark matter human might be right next to us, it would be invisible, we would go straight through them (because there's no electromagnetic force affecting them)... we'd both just live our lives and never meet.
But they say dark matter doesn't stick to each other, so there's probably no parallel dark earth
@RDE Lutherie Gravitational lensing comes to rescue! :)
Dear Dr. Lincoln, as you mentioned Chien-Shiung Wu I am sure it is finally the right time to tell more about CP Violation. I would love to hear your story.
You deserve a nobel prize!!!
Fritz was an underrated genius.
Love that picture of Fritz Zwicky!
Hi Dr. Lincoln,
Really love your videos! A silly question: since according to the general theory of relativity, gravitation is not a force but just the distortion of space-time, does it mean that two absolutely stationary objects won't attract each other?
Nice haircut Don! Are you giving us a demo on the effects of static electricity? Fabulous video, very enjoyable - thank you.
I know this comes in late in the series but I wonder if you could explain Princeton’s Maldacena idea of time traveling through wormholes. Thank you, you rock!
On the Nobel question, those were the same two that I immediately thought of :)
Dr Lincoln, could you do a video detailing the E8 lattice?
hey Dr. Lincoln, I love your videos, thank you and your team for being both entertaining and educating!
you mentioned in this episode, how dark matter is "a single leaf" on this tree of mystery. why is that? is it not also possible, that there are several "dark matters", each contributing to mass, but otherwise having different properties?
No he means that dark matter could be:
Particles (most likely)
Some people say it could be primordial black holes or it could be that we need better theory of gravity, and answer lies in better understanding of gravity.
What i really like about physics is that there is an answer if you want to escape reality; you gather the required energy/mass and you 've got a hole in the fabric of space and time! Probably you won't survive but it's a first step. It's really fascinating!
I don't have the background to comment on the work of Chien-Shiung Wu, but it did get me thinking: Assume there there are two people in cooperation, the one poses a profound question and proposes an experiment that could revolutionize our understanding, but lacks the technical skill and insight needed to bring to practice the experiment and get the answer. The other person, the one who didn't come up with the question, takes knowledge and techniques, refines and extends them and thought great skill and ingenuity develops the ability to construct, assemble and execute the experiment to get the answer to the question, despite very possibly not actually knowing (or caring) about it implication to the grating understanding of the universe. Both are clearly exceptionally skilled people but in different ways. They both deserve accolades for their application of those skills, but for different reason. (I'm not a scientist, but rather an engineer by training, but this strikes me as rather similar to the traditional rivalry between engineers and technician, between the people who "merely" design something and those who "merely" build and maintain it.)
Granted, that described case is an intentionally extreme division of labor, and I don't know how Chien-Shiung Wu relates to that, but the thought does, I think, suggestion that there may be good cause to formally acknowledge exceptional advancements in experimental technique and practice as a distinct endeavor from the questions and result those experiments are in pursuit of.
5:09
World Yggdrassill is confirmed
Gravity seems to exert a pull over distances great enough to bind together not just galaxies, but whole galaxy clusters. Yet we observe galaxies flying away from us - accelerating actually. So at what scales does the repulsion that causes everything to fly apart "win over" gravity?
One explanation I heard why Dark Matter doesn't form solid structures was quite intriguing.
When ordinary matter clumps together, it converts the potential energy into kinetic energy by heating up, that is, by accelerating the particles, which then release the energy as electromagnetic waves. As Dark Matter does not interact with electromagnetic waves, it cannot release the kinetic energy of its particles that way. Thus the particles are getting higher and higher speeds until some of them reach the second cosmic velocity and leaving the gravitational field of the clump again. Any concentration of Dark Matter will disperse itself again because it can't release the energy as electromagnetic waves. In general, Dark Matter will always remain an amorphous blob of something that keeps running on ballistic trajectories.
Qualitative Dark Matter idea I've had for a while. In GR space deforms. It is the stiffest substance in the universe actually. But, GR postulates that space is 100% elastic. All physical solid substances. like steel, deform both elastically and plasticity. (i.e. creep) Question. Has anyone tried with any success to explain dark matter by adding a "creep" to GR? It would be observational and testable, since you would see more dark matter around a galaxy as it ages. This idea would predict phenomena like the "Bullet-Cluster".
Also, I love the series. I enjoy every episode immensely.
Sherlock Holmes’ (or rather Sir Arthur Conan Doyles’) statement is actually a logical fallacy, because it should actually state: “Once you rule out the impossible, whatever remains *provided it is within the spectrum of options you are considering to begin with*, must be the truth”. It’s a subtle but critically important distinction because if you aren’t considering a full spectrum of possibilities, however outlandish those may seem a priori, you’ll end up with a biased conclusion. It’s sort of like what mathematicians mock as “reductio ad importable”: you must actually show what you’ve reduced to is utterly absurd and not merely unbelievably outlandish.
What are the upcoming experiments you are most looking forward to? I know one of them has to be the G-2 experiment
Hi Don, thanx for these brilliant shorties. I have a question. As far as i know Dark Matter is the webs in space holding clusters of galaxies together and hence I assume mirrors or drives the trajectories of those clusters. Considering that each cluster may house inside one or more massive black holes (or perhaps just hanging out somewhere close), and with Hawking radiation helping would it be outrageous to believe that Dark Matter may be entangled particles with those stuck inside the holes of doom? Like no electromagnetism and retaining some heavy gravity action due to the nature of their forever sorry partners. thanx
Hey Dr. Don,
I have a slightly off-topic question on some slightly fringe topics.
So youve discussed the three generations of matter before and I cant remember if youve talked on quantum fluctuations and false vacuums, but Im pretty sure Matt O'Dowd has (and for some reason I associate your channels). I dont have much formal education in these physics topics (Im in biotech) so Im sure im about to mess something up (or sound non-sensical) but from what I understand, through inflation, a locally flat area of a not-so-flat area can stretch into a flat universe, which given the right constants would expand infinitely, and that this would cool that universe (eventually) to the vacuum energy. Youve also stated in your leptogenesis video that the earliest moments of the universe would have had temperatures too hot to have a non-zero Higgs field resulting in a state in which some funky physics could take place. Also from what I understand, quantum fluctuations may lead to changes in universal constants or more likely the collapse of a false vacuum state which would result in a lower-energy vacuum state in the effected area. I also believe that we havent observed the other two higher-energy generations of matter(?).
So my question is this:
Is it possible that there is a non-infinite/closed geometry universe(?) thing that could have a very high false vacuum state that randomly drops a bit every now and then (I dont know how time would work here) producing local inflation events with slightly lower vacuum energy. I would assume that these higher energy "patches" could have the energy densities to produce the other generations of matter(?), though Im iffy on this due to the higgs/mass breakdown at these proposed temperatures. But if this isnt a series of non-sequiturs, would it stand to reason that a potential conclusion is our patch is a "cooler" patch with-in a patch, etc.
Or in a different way, could there be "generations" of universes nested within each other with potential dead universes having a quantum fluctuation event resulting in a vacuum state collapse which would be the inflation event of a new universe which was "powered" by the energy released by the collapse.
I understand most of the stuff in here is purely conjecture and unfalsifiable, but Im trying to understand how a bunch of the more "fantastical" bits of physics work with each other. Ive always been fascinated with origins and "why?" so any feedback you could give would be greatly appreciated. Like, I MUST know how everything works and its sad that thats not really a feasible goal, lol.
PS: you answered one of my other questions and I am extremely appreciative. It was, like all your work, super simple and succinct and easy to understand :)
Double slit experiment. If you extend the distance of the screen from the slits to a significantly large degree such that the diffusion pattern covers a large area. So you have your photon emitter at A and four stations B, C, D & E a large distance away and away from each other who each have a screen and receive a single band of the diffusion pattern. B & C receive the main two bands and D & E receive outer bands . If station B or C has a detector setup just before the screen, the detection of the photon before it hits the screen would force the photon to have gone through only one of the slits, this would mean D & E never see the bands for that photon and they only arrive at stations B & C. If the detector can be switched on and off by a switch would that cause the bands at D & E to flash on and off at the same time, thus transferring superluminal information?
Thanks for your videos Dr. Lincoln, they are always very interesting, I 'm not a perfect English speaker, consequently I loose some words or verbs...., anyway I go to watch it a second time, take care and greetings from the land of Democritos....
Black hole question. What happens with space if a black hole evaporates due to Hawking Radiation? A black hole has a singularity which has infinite density and infinite curvature of space.
Yes, Wu deserved that Nobel prize definitely!
Regarding the formation of heavy elements there was an interesting paper last year which showed that to get the observed metallicities of galaxies in the local group based off what we know about their star formation history that there needs to be at least two different phenomenon acting on distinct timescales one of these appears to dominate in galaxies with lots of sustained active star formation suggesting timescales of a few million years as is typical for massive dying stars. The other process is delayed by a few billion years after pulses of star formation.
From this is seems safe to conclude there are at least two processes. The latter of these perfectly matches up with the expected time for Neutron star binaries to in-spiral so that seems to support the observations of neutron star mergers as a source of r process elements, however the other one has a timescale typical of massive dying stars suggesting something related to core collapse supernovae.
As for the elephant in the room of dark matter clearly there is something going on. right now the best evidence for particle based dark matter seems to be limited but things like Sterile neutrinos or axions seem to be far better fits than WIMPs as they don't require the same load of assumptions as super symmetry particularly as the more plausible candidates have largely been ruled out. The similarity in the speed of light to gravitational waves and discrepancies in cluster structures seems to strongly hinder the main competitor MOND and related empirical models. Plus there is the whole lack of a relativistic MOND model and more importantly a lack in the explanation for the variation as MOND is empirical based on observations of the rotation curves of fairly isolated calm galaxies. Over on Sabines channel I did hear about an interesting hypothesis based off noticing the additional terms from MOND apparently looking similar to the equations of state of a super fluid thus suggests that the discrepancy in galaxy rotation curves might be explained by a form of dark matter which undergoes a phase transition. It seems like an interesting idea because in principal if you can observe rotation curves of ancient galaxies if true there should be some epoch where the rotation curves of galaxies would change from cluster like to isolated galaxy like. With its non interacting nature I don't know for sure how such a phase transition could happen but perhaps something related to the formation of a Bose Einstein condensate? The possibility of some observational test is what interests me as it would answer at least some part of Dark mater's mysterious nature.
You wouldn't happen to have the title or document id of that paper? (not sure whether links are allowed here)
@@michaeldamolsen I may have gotten the year wrong since they all blur together particularly 2020 or the wording in the preprint abstracts has been changed since it was something I saw on my Astro PH feed
arxiv.org/abs/1809.03525
arxiv.org/pdf/1905.12016.pdf
arxiv.org/pdf/1909.06328.pdf
arxiv.org/abs/2008.04660
or somewhat more exotic and related thing I found.
arxiv.org/abs/2003.00972
@@Dragrath1 That's excellent! Thank you so much for taking the time to look up those links :)
10:41 =))) brilliant
He's got the brains and the looks.
Hey Dr. Don, if we can both watch the Sun grow into a Red Giant from a nice bar, I'll buy you a drink!
There’s a restaurant I’ve heard of with a nice view of such things, though I suppose one of you will have to invent a Heart of Gold first.
@@altortugas5979 Lots of patrons seem to have made it there without such a vehicle.
Excellent, video Dr Don! I don't know if I watch your videos to be enlightened or to catch your wry humor!... OK it's both!
Thus establishing that you are a person of impeccable taste.
Great video as always Dr. Don! So, is Dark Matter (DM) similar to Gravity (G)? I mean we can't see "G" but we can measure & observe it's effects on objects, etc.. Therefore, why can't we do the same for DM? IF we do manage to find DM, what would be the implications of such a find other than simply knowing it's there? Thanks!
Dark matter, pretty much by definition, IS a source of observed gravity, for which that gravity is the only sign of it we've seen.
My Question for the week: How do physicist tease out the difference between a star/galaxies true position vs it's apparent position due to gravitational lensing, particularly when talking about dark matter lensing when you can't reference the nearby object's mass? There are some cases where it's fairly obvious (Einstein Rings & Crosses).. but when the distortion isn't that extreme, how do we figure that out? (I'll admit, this might be better targeted at Dr. Becky Smethurst over on her channel, but the topic this week make it leap to mind.)
Dr. Lincoln, the conjecture is that dark matter only interacts with regular matter via gravitation. But as we know, gravitation is spacetime curvature due to the presence of energy (typically in the form of an aggregation of the mass-energy of matter). Therefore, isn't it reasonable to conclude that dark matter represents a form of energy? If so, what, then, is the difference between "dark matter" mass-energy and "dark energy"? Thanks!
Hi Don. In which direction is Einsteins equation E=mc2 moving for the universe. Is energy gradually being converted to matter or the other way around. Or in balance?
Thank you for shedding some light on such a... dark matter! If such particle exists and emits no radiation, does that means it also cannot absorb any thus be at absolute zero?
Hi Don, I am wondering if there is relation between the ferromagnetic properties of iron and its nuclear stability? I will be grateful if you can shed light upon this topic. Thank you!
Dr. Lincoln, thank you for your interesting video.
I have a question: can dark matter be another family of neutrinos, or sterile neutrino?
Thanks Dr. Lincoln! Chemistry Cat agrees, physics is everything
What about axion??? It's is also related to super symentry. What's ur thoughts sir??
Dear Sirs. As reference, the paper where is described a solution of the rotational velocities observed in spiral galaxies, without using dark matter (but adding the Coriolis force in the rotating system, from the General Theory of Relativity), is the following (from 2020):
article.sapub.org/10.5923.j.astronomy.20200902.01.html
Please don't forget to include variable speed of light (VSL) theories in the next video, which perfectly explain observations without need of nor dark matter, nor dark energy.
Except that VSL is ruled out by lots and lots of empirical data, just like the Electric Universe bunk.
Along the lines of “Who would you give a Nobel to”, I often play the game of “Who would you visit if you could go back in time and what would you bring to show them?” Any thoughts, Dr. Don? Others? (A derivative game, “How would things be different today if you filled them in using current knowledge or dropped off a modern object of relevance to what they worked on”) These are best contemplated laying in a hammock on a cool, sunny Saturday afternoon.
I am sure you have a lot of questions Dr. Lincoln but I would like to know how if am moving through space, how do I know I know how I am moving through space as well?
Hi, Don! Can dark matter fall into black holes? What signs of this might we look for in quasars?
Sir is it possible to learn from you that too a course completely filled with basics of particle physics??
Dr Lincoln: How do astronomers determine the mass of distant objects like galaxies just by looking at them? Is it possible that the rotation speed discrepancy is just due to astronomers' methods for measuring the mass of galaxies was wrong in the first place? Help me understand.
Amazing Awesome Cool Video
Q for Dr. D , is entropy the opposing force to gravity? If so, is there a particle that convey's the force? Thanks Nick.
Here's a question I have asked many respected astrophysicists, cosmologists, and astronomers, and none have answered so far: How can an instrument like Planck see through the 200000+ galaxies (and growing) , many with trillions of stars that exist in a single pixel as demonstrated by the Hubble Extreme Deep Field, to resolve the tiny signal from CMBR? Forgiving the "cancelling" of the Milky Way, which is not possible with any known non-coherent blind adaptive cancellation technique, cancelling quadrillions of stars which definitely have plenty of signal throughout the microwaves is not explainable by anyone so far.
I really cannot understand why it's expected that stars near the center of galaxies orbit slowly, as they suffer much more acceleration from the black hole's pull than stars far from it !
Chien-Shiung Wu was one of my guesses for people you would award a Nobel to, but if we expand the number of prizes you'd give out, I'd say Lise Meitner should probably be high on that list as well.
Sure. There are lots. And not all are overlooked women. Hubble comes to mind.
@@drdon5205 And I was so shocked that Hubble didn't get one that I had to Google that to see why it happened.
Taking note of the books in the library
Thank you very much for the free education that you produce everyday. I have a question: If dark matter is matter but it doesn't interact with light, could you 'be walking on space' and stumble (feel you collided with) an "invisible object'?
That is essentially what happens to light that gets lensed by dark matter. It seems it doesn't clump up enough to actually trip over it or bump into it, though, and if it did, you'd only feel its gravity. tripping over stuff or bumping into stuff while walking is an electromagnetic interaction.
Michael Bishop thanks for the answer. So if this kind of matter does not care for electromagnetic interaction, we would just “walk right through it”? Only our gravities would interact?
@@alanboro That is correct, according to our current understanding.
When you feel the bump of an object you are "feeling" the electromagnetic interaction between your molecules and that object's molecules.
Talk about why does entropy always increases with time
LINCOLN! Just to mess with people you should lodge an odd book, like a kid's book, in that book shelf. I did this to the law-enforcement library where I work. RUNAWAY RALPH is still there, 6 years later.
Okay, so emulsify olestra, water, and lecithin, add tagatose, carrageenan, and vanilla, put it in an ice cream churn, and you have calorie-free non-dairy frozen dessert. It may taste bad, and would have horrible GI effects, but it's calorie-free "ice cream".
If Dr. Don Lincoln lives for five billion years, he might see a theory of everything in his lifetime :)
I'd like to hear how they measured the mass of galaxies. Margin of error?
If you know the apparent brightness of the galaxy and the distance, you can figure out the actual brightness. Since you know the brightness from a single star, you can use the mass of a single star to work out the mass of the galaxy. There's more to it, but that's the big picture.
@@drdon5205 And even if you don't know the exact mass of a galaxy, you can figure out the distribution of mass from observations. At least, the distribution of visible matter.
Using that, we can still arrive at the conclusion that the galactic rotation does not match our predictions.
Hi Don.. isnt it possible that in the middle.of galaxies those supermassive blackholes make things move slower and more far from their influence it is just kind of constant, like a constant speed of starts or smth? That chart seemed to show that
Question for next episode, how do we know that "dark matter" isn't just weird space-time geometry?
If dark matter is weird space-time geometry, there would be an explanation for why there's weird space-time geometry, which scientists would then need to explore (because that's what scientists do).
@walentaz let's wait for answer, I'm afraid it may work in both directions
Can you Do a show about Niel Zuruc . I Think He is on to some thing ! But i need more expert to back or dismiss my hypotese ( some even theory )
I think Edwin Hubble was worth a Nobel Prize as well.
He's also on my list.
I second your Nobel choice!! 👍👍
Hi. I would like to ask that, all the stars , black holes everything is changing matter to energy . So at last we might don't have any matter left, is that right ? And could we turn energy into matter like stars convert matter in to energy in a huge scale ?
one day the universe will be made only of neutrinos and photons with the lowest possible frequency...