The edge of human understanding of the universe is a vague and scary place. When we dug deep below the atom level everything we took for granted fell apart. We had to invent an entirely new model of physics to make sense of our observations, which is complex and counter-intuitive (quantum mechanics)

Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the super-galactical? Could the rules at such scales necessitate a new form of physics that we have yet to derive because of the difficulty of observation?

I ask this because "dark matter" and "dark energy" always make me think of past primitive attempts to align unexpected data to existing models of understanding. Is it possible that they are just "echoes" or "shadows" of concepts that exceed the very nature of "matter" and "energy"?

The point I always make when this comes up is: epicycles, negative-mass phlogiston, æther and all the rest were good physics at the time. People who used them made more accurate predictions than any alternatives.

So yes, dark matter and dark energy are probably not the full story. But they are the best model we currently have, and it's very easy to criticize and much harder to offer a positive counterproposal.

A great book on good physics which did not pan out is http://www.amazon.com/Higher-Speculations-Theories-Revolutio...

Vortex theory was very cool, but not how the world worked.

True, but we've come to seek more than just predictive models, we want understanding and "truth".

I'd say the opposite; we've come to realise that accurate predictions are the truest benchmark and notions of understanding can often be misleading.

But supposing you're right, so what? Unless you'd prefer a more understandable but inaccurate model, there's still no better alternative to dark matter or dark energy.

You need deep understanding to develop the next set of accurate models and - perhaps - turn them into useful technology.

Agreed, but I don't think going back to theories that don't explain all current observations is a fruitful path there.

Until you have a better predictive model there's no way to tell what you had before wasn't the "truth".

Yes there is. Models can be disproved by empiricism without needing another model.

However, even if a model doesn't work all the time, it doesn't mean it is useless for prediction. Newtons laws is still in use, for example.

He means the most common definition of truth is 'The best predictive model' (in the scope of the problem). I would add the principle of parsimony, truth is 'The simplest available formulation of the best predictive model'.

In both cases you cannot know that no better predictive models exists (and hence if your truth is absolute), even if you experimental error is zero (which is essentially impossible in most sciences unless you grossly overfit), since there may be unobserved phenomena as well.

Newton's laws weren't disproved, they were just shown to be less general than originally assumed. Quantum theories usually assume Newton's laws to be true axiomatically, otherwise the quantum theory would be under-specified and practically useless.

Truth is just a sufficiently correct predictive model

phlogiston was actually better than the theory which immediately replaced it (oxidation, etc.) - they were close to discovering electrons ... but by involving oxygen delayed that realization for quite awhile

In a way relativity theory was such a new model, classical theory (Newton) worked well at all Earth scale observations of the time, it took quite few years after the theory was formulated before the first experimental evidence came in and relativistic effects are far more visible to us on a larger scale (but they're there on a smaller scale too, just harder to quantify).

Who knows, there may be yet another theory that explains things on a larger scale even better than our current understanding. This may also increase or change our understanding of what happens at the smallest scales. Laws of physics trend towards unification, a single model to explain all scales at once.

That's right. Things in this Universe are not scale-invariant. We are so enmeshed in the human-scale models, that anything beyond (above, below, far away from) this scale look alien.

Growing up and bumping your head, as a toddler, into the kitchen table, you learn about a Universe that follows newtonian physics, euclidean geometry, and boolean logic. But then you look at vastly different scales and you learn that all these are human-scale approximations. The universe is post-newtonian and non-euclidean; and deep in the science of complexity boolean models are challenged by fuzzy logic.

The newtonian/euclidean/boolean model we carry in our heads is just our little insular view of the universe.

Perhaps we don't have the capacity to understand how the universe works?

I can't remember where I read it but someone made the point that no matter how hard you try you can never teach a mouse to understand French.

So I'll zig to your several replier's zags and suggest a mechanism that could potentially explain that effect. Right now we believe that the universe has an approximate spatial granularity of Planck's distance, which is ~1.6E-36, and approximate temporal granularity of 1E-43 seconds.

(Unless you can improve upon those numbers by a good 40 or 50 orders of magnitude, please don't quibble in the replies. I am aware it's not a "grid" or something, but that is the approximate resolution.)

Our best theories of the universe will have to work at that level, or even potentially below it in the case of string theory. A full theory of the universe ought to be able to describe how everything works down there. However, all the phenomena we care about and have concrete data about are literally 40 orders of magnitude bigger, at a minimum, in spatial and temporal extent.

We have proposals for how the simplest elements of the universe work. Heck, for all we know one of them may even be right. But proving that is extraordinarily difficult because of this huge order-of-magnitude gap. You'd love to be able to just plug in the theory, set yourself up a universe, and start computing, but the incredible gulf of magnitudes makes that essentially impossible. And the theories are sufficiently complicated that attempts to approximate break down in various rather distressing ways.

Even if the Great Simulator simply handed us the equations that our universe is based on, could we verify that claim?

Honestly, my guess is that with enough effort, yes... but even with the answer it could well be extraordinarily difficult. Without the answer it's even harder.

>no matter how hard you try you can never teach a mouse to understand French.

humans couldn't so far teach mouse a human language. That doesn't mean that mouse doesn't have something like several thousands or tens of thousands of basic sounds and combinations of them into meaningful (for mouse) sequences. http://blogs.scientificamerican.com/running-ponies/catch-the...

After all as a mouse says to another mouse - "no matter how hard you try you can never teach a human to understand mouse language".

The same is through the history of physics/mathematics. It takes a change in fundamental point of view. The notion of derivative took decades of work to develop by geniuses of that time. Imagine how physics/mathematics looked without it.

When i look at strings theory of today i see epicycles, a very intricate and complex system of epicycles in 11 dimensions :) We need a genius like Newton or Einstein to again see and tell us what is behind that apparent complexity.

> After all as a mouse says to another mouse - "no matter how hard you try you can never teach a human to understand mouse language".

But mice don't say that. They can't. jahnu's statement wasn't a parable.

It doesn't look like they're having conversations. It looks like they're seeing some sort of stimulus, and are making relevant noises. It's a pretty impressive reflex, but it's not a conversation - it's an announcement. It's no more of a conversation than a hungry baby crying.

> Mice and other animals do say that

Okay, find me a link that says mice complain about humans not learning their language.

>>check the various articles on animal language decoding. Mice and other animals do say that or similar complexity things.

You aren't stating the solution, you are stating the problem.

You didn't get the point. If all of humanity had limited capabilities to speak and express. Say we could all utter only 3 kinds of sounds namely x,y,z- due to that sheer limitation our language and written systems have to be expressed in permutations and combinations of x, y, z.

That sort of stuff works only for simple things. The moment you start venturing into any complexity, trying to express those concepts in only 3 ways will lead to verbosity and interplay that will blow up beyond practical ability to grasp, given limited resources to interpret them.

And take note if the animal has no means of recording information somewhere and check over time, keeping that level of verbosity in one's brain and workout complex physics is just out of question.

No but the point is a mouse simply does not have the capacity to understand French.

Maybe humans do not have the capacity to understand the complete workings of physics.

Does a human have the capacity to understand the complete workings of an Intel CPU? I doubt it.

But we augment our capacities with tools, something mice don't do.

But that could only be the case if those laws are very, very complicated. So far physical laws have been on the side of "understandable if you invest a couple years of study as a reaonably intelligent person".

We wouldn't have discovered the impossible to understand laws no matter if they exist or not.

Or we have already discovered some of the impossible to understand laws and we are desperately throwing any theory at these inconsistencies in our understanding to no avail.

> As result we're using only like 10% of capacity of our brain.

This myth needs to die in a fire. https://en.wikipedia.org/wiki/Ten_percent_of_the_brain_myth

It's been said (I don't know how accurately) that some people do use 100% of their brains. They just happen to be in the midst of a grand mal epileptic seizure.

> This dog knows 1000 words in human language. That's more than i know in Chinese, and the task of learning a 1000 Chinese hieroglyphs scares the hell out of me.

Okay; but that dog can't have a conversation. It doesn't know what they mean, it just knows that follows a certain stimulus. It's like saying I understand cloud language, because I can tell when it's going to rain after looking at the sky.

And even if that dog "understands" a thousand words, and you're scared of learning a thousand Chinese characters, you still have the capacity for learning Chinese. Or French. Or Spanish, or Esperanto, or Russian, or Thai. You could spend a year learning Russian, and we could have this conversation in that language; I will never be able to explain this conversation to a dog, in any language.

>Okay; but that dog can't have a conversation.

dogs do have conversations. And other animals too. Check the link on the prairie dogs for example.

>I will never be able to explain this conversation to a dog, in any language.

it is the deficiency of human-to-dog communication, not the dog's lack of mental capacity to handle the complexity of conversation.

> to the comment below on 10% - there is a difference between 10% capacity and 10% neurons. The fact that most of our brain is physiologically participating while producing that little capacity most of the time in most of the people is exactly the low efficiency i was talking about.

And still no. Phrase it however you like, it's still wrong. You are not using just 10% of your brain in any manner or means, there is not some great untapped potential waiting to be turned on, your brain is not low efficiency.

You'd probably be better off linking to something like this: http://www.rifters.com/crawl/?p=6116

Or this: http://rifters.com/real/2009/01/iterating-towards-bethlehem....

Less than a million neurons and Portia's interpreting complex visual scenes and making detailed attack plans.

While "we only use 10% of our brains" is clearly bollocks, the implication that our brains may not be particularly efficient for our level of intelligence doesn't seem too unlikely given the way evolution works - our brain's a crudely scaled-up pile of accidental hacks guided by endless local maxima it can't readily escape from, it'd be very surprising if you couldn't improve on it.

You might draw parallels with modern computers. All these transistors to play with, but we're certainly not using them as well as we could - we're limited by the software we want to run and know how to write using our existing tools.

Does the dog have the capacity to understand how the universe works? Does the dog have the capacity to understand physics to the degree that we understand it now?

No. So the dog has its limits, as we have ours. Where the limits are is certainly up for debate, but hard to believe there is no limit.

Chinese characters are not 'hieroglyphs.'

And they are logograms, or at least they compose a logographic system.

Well, the irony is that string theory IS the attempt at the elegance behind the apparent complexity of the standard model. But I agree with you that dark matter and dark energy are undoubtedly works in progress (if that's what you were trying to say)

That point of view is inherently untrue. We have an extremely good understanding of how the universe works. The Standard Model has been worked on since the 40's and has been experimentally proven and refined ever since.

There are things the SM doesn't account for yet, such as dark energy, dark matter, and gravity. That doesn't mean it's beyond human understanding, just that there's more to the universe we haven't discovered yet.

In the worst case, those things will have interesting but not surprising answers. Slight modifications to the SM to account for some new particle types, etc.

In the best case, they turn out to be something completely unexpected and the SM turns out to be the equivalent of Newtonian theory. Perfectly good and accurate theories about the nature of the universe that are just a subset of a wider physics model, like how Newtonian theory exists within the Standard Model.

> Perhaps we don't have the capacity to understand how the universe works?

We don't understand QM but we can still use the equations to make predictions..

You're suggesting that we can't create better equations which explain more the universe? That's quite a bit early to say that.. I'm more worried about our possibility of creating experiments which can be used then to select which equation is the right one.

I think they meant that maybe we can't discover the final entirely correct ones.

That depends on how long the mouse has to be taught. If we had 1,000 years I bet we could do it.

I don't think mice live for 1,000 years so there is a slight problem with your theory.

My point was that humans can pass acquired knowledge to future generations. Given enough time, we can figure out things that would take too long for any one generation to understand on their own.

Yes, but your example is both irrational, poorly chosen and simply will not work, no matter how much time we have since it requires the co-operation of the subject which simply does not have the neural apparatus to comprehend speech as we generally understand it. So no, given 1,000 years we will not be able to teach mice French, nor Russian, Chinese, English or any other human language.

There's more to that than simply wanting it to be so, no matter how much information we can pass on to future generations.

Individually, probably not, but as a eusocial organismwe quite likely do.

Possible! There certainly is a lot that feels inelegant in the dominant model, and nobody has yet proposed a reason that so much of the universe would be so oddly invisible to us.

But (as I just noted in some detail in a different comment here) the "Lambda-CDM" model of a universe evolving in the presence of a cosmological constant and cold dark matter has proven to be quite remarkably consistent under a wide variety of very different observational tests. Everything from supernova data to the cosmic microwave background to large-scale cosmological structure/cluster formation is not just in agreement with the general outline of that model but even gives consistent (and increasingly precise) values for the parameters of the model. (They all lead to pretty much the same value for the percentage of dark matter in the universe, for example. Here's a typical graph from 2003 that I found from a Google image search: https://ned.ipac.caltech.edu/level5/Sept09/Einasto/Figures/f... The different-colored ovals near the middle-left represent entirely different observational data.)

So I would love to learn someday that all these weird phenomena are manifestations of some deeper, more elegant truth. (I've done some limited research vaguely connected to the area myself, though that was long ago and my current focus is much less directly relevant to this topic.) But whatever that deeper truth turns out to be, we can have a whole lot of confidence that it will manifest in a way that behaves an awful lot like the dark matter and dark energy models that are being studied today.

> nobody has yet proposed a reason that so much of the universe would be so oddly invisible to us.

IANAP, but it seems pretty consistent with the brane element of M-theory to me.

If you have a bunch of 3-dimensional branes sitting next to each other in a hyperdimensional bulk, and gravity is the only force which can pass between them, then of course you're going to end up with what appears to be invisible matter. It's the aggregate mass that has clumped together in the respective 3D branes, as close as is possible to the adjacent branes.

E.g. dropping one dimension, stack some glass sheets and magnets, with the two interleaved. The magnets on one level will be affected by the fields on other levels, but any 2D flatlanders on any given level will be unable to actually see those other magnets. It will be as if some ghostly "dark magnets" are passing right through their own.

Poor phrasing on my part, I think. Brane models (whether in M-theory or elsewhere) are certainly one way of producing this sort of phenomenon theoretically. (I've done research on branes in both string and M-theory.) But ultimately, what you've described is just as arbitrary as declaring "this quantum field has no electric or color charge": there's no reason known that we'd happen to have those two brane stacks in the right positions to mimic ordinary matter interacting with dark matter. (Why exactly the right branes and intersections to reproduce the standard model? Why also this separate brane or branes at a carefully chosen distance to have meaningful gravitational interactions but not gauge interactions? What stabilizes the separation of the branes over cosmological timescales? etc.)

> nobody has yet proposed a reason that so much of the universe would be so oddly invisible to us.

Whilst I don't claim to have an answer to this question, I still wouldn't call it "odd".

We know of four fundamental forces (strong, weak, electromagnetic and gravitational) and we know that some particles are unaffected by some of these; e.g. leptons don't feel the strong force and neutrinos don't feel the electromagnetic force.

I would say the odd part is our assumption that matter should be visible (AKA electromagnetically interacting).

(Note: I'm only talking about dark matter here; dark energy is odd ;) )

> Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the super-galactical?

Isn't special relativity complex and counter-intuitive enough?

I don't think special relativity is quite on the same level of strangeness (no pun intended) of quantum physics. For one, the axioms of special relativity are actually pretty believable, not to mention the incredible elegance of its integration with classical electromagnetism.

And the metaphors for relativity hold up longer than a few seconds once you start asking questions.

Interesting point. Also, if you look at the time scales, QM wasn't really discovered until we could get tech to go that fast. We had to 'see' it at the 'speed' it was going, otherwise it just blurred out (not just speed but distance and many other units had to be very very finely tuned).

Perhaps with the super large, everything seems to be more static than we'd like it to be. To get a good sense of the systems, we need to let it happen for longer than we have thus far. Dark Matter is an example. We had to watch the stars to figure out they were not spinning at the right rates, and that took a long time to be certain of.

There is a balance here though. With QM it was just a few things, with astro, it is a universe of things and that takes a lot more 'eyes' to be certain of stuff.

I leave out black holes and the interface of QM and GR, because that is a hell of a lot of stuff happening really fast at really small sizes. Granted, it's the interesting stuff, but I feel we have to get real experiments going first before it is prudent to look at. That means some really big telescopes looking for really tiny variations for a really long time. Something funding bodies are not able to justify as of yet.

"Would it be reasonable to assume that the same applies at the opposite end of the spectrum: from the sub-atomic to the super-galactical?"

I suspect that its what we don't understand about quantum mechanics what finally will explain the macro observations that we don't understand.

After all, macro observations have to derive from the fundamentals and it seems that the fundamentals are in the quantum realm.

I have a similar sentiment. I know nothing's of physics beyond high school stuff and popsci, but to me Dark Matter feels like "aether 2.0". I'm probably wrong.

That is exactly which brought me to the BSM-SG model. When nothing seems to fit well and the physics appear stranger and stranger, you should ask yourself: did we do everything right ? Did we do some mistakes in measurements ? Do we have some some wrong assumptions ?

Turns out: yes. If you remove those wrong assumptions, you end up with a classic logical model that makes sense in very aspect. QM is just to raw for explaining the quantum world.

Things seen as fundamental particles that are huge, huge structures. Even to look only at energy and ignore form and geometry (by definition), becomes absurd with deeper understanding.

When googling "BSM-SG", the top result is a thread (by poelzi) on a cold fusion forum... Which contains this nugget:

"If Quantum Mechanics describes the Atom, why does it not provide the angles atom create for chemical bindings, every chemistry student has to learn?"

Really? You couldn't be bothered to sit down with an organic chemistry textbook and discover that QM is the basis for our entire understanding of how atoms form chemical bonds? You've never heard of sp3 hybridisation? E.g. Paula Bruice's book "Organic Chemistry" starts with QM as the most fundamental piece and builds everything from that. Read it.

Hybridization is this wierd fiction. It's trivially true because you can create any orbital via conservative linear combination of other orbitals, but only some of them will be energetically meaningful.

What hybridization would you expect water to have? You're wrong. It's not.

http://www1.lsbu.ac.uk/water/images/h2o_orbitals.gif

But our current qm are really bad at predicting bond angles. Vsepr is basically a geometric argument, and most of our understanding of bond angles is strictly emperical.

> Compare the Atlas of BSM-SG model with what QM provides and you will see, that the angles of the BSM-SG model are much more precise what complex chemical structures look like.

So I looked at all those pictures in the viXra paper, and there is not a single chemical bond or molecule anywhere. Care to explain?

There is a more detailed paper about it:

http://goo.gl/U2BHBL

I don't expect you to understand, took me month before it clicked and started to make sense. In fact, at some point I had to take a week off because I was so into the theory, I could not think about my dayjob ;)

Currently the main book is the only way to understand the theory more deeply, but one of our projects is, to do a video series explaining the model in a simple way. As a scientists, you will need the book until somebody writes a comprehensive one as well.

http://www.amazon.com/Basic-Structures-Matter-Supergravitati...

The papers helped me to get into the theory, but real deep understanding is not possible from them.

http://vixra.org/pdf/1107.0031v1.pdf

What you see in the atlas are the proton and their geometric structure as they grow. These are not electrons ! There are some electrons drawn in on the H atom to show some of the different energy states.

You seem to be acquainted in physics, so, whats your explanation for our well tuned universe. The number of basic constants in the standard model is so high and simulations have shown, that small changes cause an unstable universe. In the BSM-SG model, all those constants and relations are derived. In fact, after some month you understand this: the fundamental growth principle and the geometric configuration nearly always lead to stable atomic structures and galaxies as we know them.

(There are some open questions and there is the possibility that when a matter - antimatter galaxies collide, some unstable galaxy could result. Maybe ill-formed galaxies are an result of such mergers).

Anyway, if somebody gives me a theory that is self stabilizing, derives all constants with very high rescission, fits so well to observed data and uses only 3 dimensional euclidean space. 1 fundamental force and 2 fundamental particles. Sorry, this is just the better theory.

Many people are not firm with logic and only know mathematical logic. Every logic is based on different fundamental assumptions, this is something you have to believe in for a logic to have a truth value for you. Classical logic is simply stricter then mathematical logic and has therefor a higher truth value.

In classical logic this you can't do: https://www.youtube.com/watch?v=q43sqytcdLE

What are you talking about? QM is the most elegant, beautiful, and empirically verified theory ever. What does your "classical logical model" say about the Bell inequalities?

This seems like something straight out of SciFi. Dark matter actually forming invisible rods that go through the Earth? Can we interact with these "hairs" if they are all around us? Can we at least detect it?

It seems that all question I and any non-specialist can ask are stupid and irrelevant, but it's still so exciting to think of all the possibilities.

My vague understanding of this article is that what's being described is more like the bright "caustics" that you see when light shines through a glass of water (https://en.wikipedia.org/wiki/Caustic_%28optics%29).

The notion is that a massive object like the Earth would act something like a lens, gravitationally. That isn't usually apparent, because most types of matter and energy would simply be absorbed when they hit the Earth. But dark matter (according to our best guesses today) can pass straight through the Earth just like light through a transparent object. So if there really are "streams" of dark matter all moving the same direction passing through us, they would act analogously to light rays through an ordinary lens. (And since there could be multiple streams going different directions, it could wind up looking like several light sources shining through that glass of water, with these "hairs" or focal points extending out in several directions.)

The two questions that come to my mind after reading this brief article are, 1) does the same thing happen with, say, solar neutrinos? (Maybe they're just too fast for the effect to be meaningful?) And 2) if they're going to talk about how much more Jupiter does this focusing than the Earth does, is there a reason they didn't go all the way and talk about potentially even stronger "hairs" created by the Sun itself? (Maybe those wind up focusing inside the star?)

>This seems like something straight out of SciFi.

I really don't see why!

"He now seated me near the machine, so that it was on my right, and turned a switch somewhere below the crowning cluster of glass bulbs.

[...]

I felt the huge animate things brushing past me and occasionally walking or drifting through my supposedly solid body [...] Suddenly I myself became possessed of a kind of augmented sight.[...] Indescribable shapes both alive and otherwise were mixed in disgusting disarray, and close to every known thing were whole worlds of alien, unknown entities. It likewise seemed that all the known things entered into the composition of other unknown things and vice versa. Foremost among the living objects were inky, jellyfish monstrosities which flabbily quivered in harmony with the vibrations from the machine. They were present in loathsome profusion, and I saw to my horror that they overlapped; that they were semi-fluid and capable of passing through one another and through what we know as solids."

- H.P. Lovecraft, From Beyond

As I understand, we can detect them through their gravitational effects and not much else. If we fully account for the pulls of all the non-dark bodies in the vicinity (Earth, Sun, Moon) and then manage to measure an anomalous gravitational pull (say on a mass connected to an extremely fine sensor) that changes with the motion of the measuring apparatus, that (I think) ought to do it.

Disclaimer: not physicist.

actually, there is something that it is not really understood: the 5.9 years period of gravitational constant variation. [1]. Maybe the Earth is passing through such a filament?

[1] http://phys.org/news/2015-04-gravitational-constant-vary.htm...

Interesting! But... it's been 15 years since my last university level physics course, but those error bars in the plot doesn't exactly lend lot of confidence to the idea of a periodic pattern?

There's been a follow-up paper from three scientists whose independent G-measurements reach some of the lowest-claimed uncertainties.

http://arxiv.org/abs/1505.01774

Not a physicist either. But from what I understand from Lawrence Kraus's lecture 'A universe from nothing' is they found light bending(A phenomenon similar to gravitational lensing) around a massive start cluster, the amount observed and the mass in that area was insufficient to explain how that kind of phenomenon was possible.

When looked at from the perspective of Gravitational lensing[A phenomenon that bends light] there is some kind of aether 2.0 with a mass that causes the gravitational lensing effect.

Personally I think this is the wrong approach to work with this. We know that a cause c1, was the result of phenomenon p1. We are assuming another cause c2, which is very similar to c1 MUST also be happening due to p1.

It might very well be there is a phenomenon p2 responsible for c2.

We seem to be trying to state cause(dark matter) in terms of its side effect(phenomenon similar to gravitational lensing) without understanding what it actually is.

It says in the article that the "root" is twice as far as the moon, and the "tip" is twice as far away as that. So the dark matter passes through the Earth momentarily (which I thought was accepted and the whole point of those deep underground observation experiments), but the "hair" itself forms quite far away. Hence the mention of being able to pinpoint one or more and sending a probe to gather information.

> which I thought was accepted and the whole point of those deep underground observation experiments

Those are mostly neutrino detectors https://en.wikipedia.org/wiki/Neutrino_detector

The arxiv pre-print is http://arxiv.org/pdf/1507.07009.pdf

Thanks! (I usually link to the arXiv abstract page rather than to the PDF: http://arxiv.org/abs/1507.07009 .)

I find this fascinating, but still purely hypothetical, yes? Basically:

IF the observed expansion of the universe is indeed due to dark matter as we think of it, and

IF such dark matter exist as streams, and

IF such streams mix with ordinary galaxies, and

IF the solar system is passing through such a stream

THEN Earth MAY have dark matter filaments in its vicinity.

IF we locate such a filament and send a probe, we might be able to learn about dark matter directly.

Fingers crossed. That would be an amazing discovery.

@ 'berntb, you've been shadowbanned for unclear reasons IMO, FYI.

Their dead comment:

    You are mixing up dark matter and dark energy. The main effect of dark matter
    is not universal expansion, it is from both influences of gravity on galaxies
    and theory.
    See e.g. https://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

I don't see their comment as shadowbanned, even when not logged in.

It was shadowbanned before, but apparently it isn't anymore.

> IF the observed expansion of the universe is indeed due to dark matter as we think of it, and

The accelerating expansion of the universe is thought to be caused by dark energy, not dark matter.

You are mixing up dark matter and dark energy. The main effect of dark matter is not universal expansion, it is from both influences of gravity on galaxies and theory.

See e.g. https://en.wikipedia.org/wiki/Dark_matter#Observational_evid...

The universe does not expand: www.cosmology.info/newsletter/2014.05.pdf

I follow the BSM-SG model in which dark matter/dark energy is absolutely clear what it is and how it functions. The illustration is even a bit similar to the BSM-SG model, if you see it as the CL dimensions. Larger astronomical bodies have their own CL space, which means they carry a bubble with them those geometry is dependent on the body itself. This is why the photons get into a gravitational pull on heavy bodies, time goes differently, ...

The Big Bang model of cosmological history is one of the most exquisitely tested ideas in science. Just for starters, any competing model would need to duplicate the highly sensitive predictions of Big Bang Nucleosynthesis (https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis), the results of detailed simulations of structure formation (https://en.wikipedia.org/wiki/Structure_formation), and the existence of the cosmic microwave background (https://en.wikipedia.org/wiki/Cosmic_microwave_background) (and at this point it would probably need to match the detailed spectrum of the CMB at least as well as inflationary models do).

That's not an impossible task, but it's an awfully high bar: the widely accepted "Lambda-CDM" model (a specific Big Bang scenario involving both dark energy and cold dark matter) and its parameters have proven to be amazingly consistent under a whole bunch of very different observational tests. The odds that it has passed all of those tests so very consistently purely by dumb luck, while the universe actually follows some entirely incompatible set of rules and history, seem vanishingly small.

In case this isn't immediately clear, BSM-SG is crackpottery akin to https://en.wikipedia.org/wiki/Time_Cube

explain: I take logic errors or math errors seriously, everything else is just crackpot talk.

Do not forget errors of fact (which are not logic errors).

A statement can be logically deductive, and contain no arithmetic errors; yet be based on propositions which do not have true interpretations in this universe.

What I meant to say was: our observations with regards to expansion (or lack thereof). Thanks for the clarification (although you could have explained some of tho acronyms you used for the benefit of non-physicists).

The previous poster probably ought to have explained those acronyms for the benefit of physicists, too: I'm a tenured physics professor specializing in high energy theory (with some research experience in relativity and cosmology), and I've never heard of that model. (Most physicists I know are also hesitant to flat out contradict widely accepted and observationally verified models without at least a bit of caution in their language, too: just saying "the universe does not expand" without qualification is unusually bold. To my knowledge I have never met a professional physicist who doesn't buy into at least the basic framework of the Big Bang model.)

First thing that occurred to me: could/would this look something like iron filings around a magnet if the dark matter stuff could be seen? Something like this. http://www.google.com/imgres?imgurl=https://apex-emovendollc...

One thing I can't figure out from the arxiv preprint is the lifetime of these hairs, which I assume are a transient and dynamic phenomenon. Does anyone have an idea of how long a hair remains near the planet in question and retains its shape?

They are present as long as there is dark matter flowing through the earth. In essence the gravity of the earth just changes the density pattern of the stream of dark matter particles the same way a lens focuses photons in the focal point [1]. So the interesting question is how persistent the stream of dark matter particles is. Also the earth is moving all the time around the sun and the centre of the galaxy and this alone should create a continuous stream because the earth moves through the dark matter background. So the even more interesting question is how dark matter is distributed - is there a more or less uniform distribution or is it patchy and the earth alternates between moving through essentially dark matter free regions and regions filled with dark matter. Unfortunately I have no answer for that.

[1] https://en.wikipedia.org/wiki/Caustic_(optics)

The good news is the idea has been put forward now.

That means, through the wonders of experimental physics, sometime in the next 10, 20, 50 years we will find out if the idea sinks or swims.

I wish the idea the best of luck, as we do need to figure out this issue once and for all.

You're not the first, second, or ten thousandth person to have this thought. But dark matter fits the phenomena better than any proposed modification of gravity. See the https://en.wikipedia.org/wiki/Bullet_Cluster for a textbook example.

Also, look at the Bolshoi Cosmological Simulation (https://en.wikipedia.org/wiki/Bolshoi_Cosmological_Simulatio...). Simulating the universe with the currently accepted model of dark matter successfully predicted the large scale structure of the universe. As a model for explaining observations, dark matter does hold some merit.

Modification of gravity has been found wanting. See e.g., the bullet cluster, https://en.wikipedia.org/wiki/Bullet_Cluster

One more interesting explanation I read in Hawking's Universe in a Nutshell, was that dark matter is extra gravity coming from parallel universes/extra dimension. Basically, what if gravity warps not just this plane, but other realities as well. It would explain why gravity is so weak compared to other forces.

Well from what I know, gravity was once a misunderstood component of spacetime bending, so it would be proper.

I had some longer talk with a friend that is much more into logics about the MOND theory. The problem I have with this theory is, that I don't think that the MAX function used, is classical logic. Unfortunately, I have not found a real explanation, but we came to the standpoint, that you require some more complex logic to satisfy the MAX function and for physics, I stopped believing in anything beyond classical logic.

I love theoretical physics - I do get tired of all the fluff articles churned out. It's like medical research. You'd think they've cured cancer by now.

If you google around for dark matter, you'll find sources, including nasa.gov saying "direct proof" of dark matter has been found already. This was back in 2006.

Theoretical physicists: disprove MOND, TeVeS, Mass in other dimensions, Scale relativity, or better yet, get better data before throwing around theoretical speculation with such confidence?

These types of questions seem to come up a lot, and while I'm not an expert, here are some typical responses, from one of the last dark matter threads (in particular, the two top replies): https://news.ycombinator.com/item?id=10550732

I assume the tendency for the general public to give higher consideration to "other explanations," relative to professional physicists who seem to lean heavily towards the "matter" hypothesis, is lack of expertise in the current state of research. If you don't have a lot of good evidence one way or the other, all options seem about equally likely, so why take WIMPs more seriously than MOND or other hypotheses? Not that considering those alternatives is silly, but I think this might explain why this question keeps coming up even though the physics community seems pretty focused on the dark-matter-as-matter hypothesis.

Though whatever the answer should turn out to be, it will certainly be an interesting development.

Essentially the defining property of dark matter is that it does not interact electromagnetically, so there is no point to consider it.

I never vote someone down, maybe three or so exception - can I look that up somewhere? That aside the page you linked to contains unscientific and plainly wrong nonsense and clearly shows no understanding of physics. I totally understand that you get downvoted for that content because it does almost the equivalent of saying that air doesn't exist because I can't see it.

That being said, it must be stated first, and bluntly, that we don't think black holes exist. If not even light can get out, how is it the cores of galaxies are shooting out massive amounts of x-rays and material?

If I was in the market to downvote someone, that last line would've sold me.

Can we please try to keep our delicate egos out of the discussion? If I wanted to see people gripe bitterly about their comments being downvoted, I'd go to reddit.

You aren't thinking outside the box, you're just spewing pseudo science about things you don't understand because the real science makes you feel uncomfortable.