Do We Need a NEW Dark Matter Model?

Always excited to see a new spacetime episode

Physicists: We like 5 sigma 0.00001 P value results to be confident of our data. Also Physicists: Interacting baryonic Matter is only 20%. Don't worry about adding it to the models.

I'm always amazed at physicist's ability to invent catchy names. Not all of their names are winners, but for a profession necessarily dominated by math people, physicists have a pretty good track record for coming up with memorable nomenclature.

Imagine living in one of these dark satellite galaxies, with only a few stars in them. The night sky would be almost black, save for a few whisps of the nearby large galaxies. Then after the discovery of the telescope the inhabitants find the sky is full of stuff. How do they make sense of it given their strange predicament?

I must have picked up a disturbance in Space Time because I randomly decided to open YouTube and saw this 27 seconds after it was posted. 🤣

Matt is Definately in my top 10 of science communicators. I would love to see more videos on the physics/ mathematics of superconductors

It'd be really cool to have dark matter's nature uncovered in my lifetime, but in the meantime I'll keep appreciating these updates on scientists' best guesses. Love the video!

I'm currently studying about both these problems in college (the Too big to fail problem and the density diversity problem). One of the explanations for not seeing the sub halos is that in some of these ultra faint dwarf satellites their star formation stopped sometime during the epoch of reionization and therefore we receive much less amount of light from them. Either reionization or ram-pressure stripping could have pushed the gas out of those subhalos very efficiently. Although this "fix" isn't completely sufficient to solve the problem entirely it's one of the explanations why it could cause such variations.

Maybe the real dark matter is the friends we made along the way.

I would love to see some FDM simulations. Should be very interesting. At the same time, perhaps we should consider hybrid solutions - those where dark matter isn't all the same, but perhaps a myriad of particles.

i'm still not convinced an invisible particle is the key to everything. with each iteration, DM becomes weirder and weirder. I've always thought it doesn't have to be a "one theory fits all" situation, to me it seems a variation of MOND plus some invisible particle (or, more likely, several types of particles) will finally be the key. Once you modify the behaviour of gravity at ultra small accelerations, you don't need quite as much DM

I can't say I understood everything, but the visuals are hypnotizing

I'm still betting that the real answer is "many of the above", with multiple dark matter candidates turning out to exist in meaningful quantities

I wonder if a mix of types of dark matter could be at play, with different mixtures having different properties; it does seem odd that so much of the universe's mass would be a single type of thing

Every time CDM is discussed I get more confused. not only about the how/why, but also about the scientific conduct surrounding this topic. I work in biomedical sciences, a different field of science, but the scientific principle is a pretty universal one and I have a lot of difficulty accepting CDM as being truly scientific. If I'd grow cells in a lab and they grow weird and my professor asks me which serum I use and I'd answer "don't worry, it's just 20% of the medium" he would tell me I'm an idiot and he would be totally right. It's a simplistic example perhaps, but I was flabbergasted to just learn that phycisists made this flaw in the simulations and that you are so forgiving about it in this video. Though I know/understand why you are, as these are your colleagues. I have always assumed normal matter was included, because that would make the most scientific sense and to my memory it was never mentioned that these were CDM-only w/o normal matter. Especially because the other 80% is so vaguely defined you'd definitely want to add the 20% of the mix which you know most about. If so, then you did an absolutely great job unveiling this. I'm not the first who argues it's strange scientific conduct to invent a particle, which is completely invisible, only interacts gravitationally, then tweak the parameters of this elusive particle in such a way that it fits observations again and then fully adopt its existence and validity. Then more particles with more assumptions are added into the mix and simulations, those also being tweaked based on...nothing?...no experimental validation or whatsoever. How's that scientific? I'm not surprised simulations show similarity with reality, as the simulation is biased by the same assumptions. This whole field of research on CDM seems to lean heavily on circular reasoning to me. We are being educated that a scientific theory is not just an idea as many think of when they hear theory. A (good) scientific theory not only describes reality, but also makes correct predictions. CDM does neither, for decades. I'm totally fine with the idea that I'm not a cosmologist, therefore it's likely way over my head and that I simply don't understand enough about it, but the scientific conduct of this whole field of science is so alien to me. I'd love to see a video which discusses the scientific argumentation and especially scientific validity for each step in the development of this model.

Great work -- this channel is phenomenal.

It seems that dark matter is dish best served cold.

every time a new space time video gets out I have to put on my thinking cap,

Wonderful dive into the challenges of explaining things

Reading through the comments, I think it’s worth a mention of why Baryonic matter was excluded from earlier simulations. My guess is that computer simulations and compute power available to scientists to run these simulations has vastly improved over the years, and it wasn’t a “lazy” oversight.