/sci/ - Science & Math

It's certainly possible, and there are alternate theories of gravity attempting to explain the anomaly without resorting to dark matter.

So far they haven't performed well, though.

>>7449796
General Relativity, and by extension Newtonian Gravity, are extremely correct though. There are many examples of how accurate the theories are, and predictions they have made. Gravitational Lensing, Planetary Orbits, solar system and planet formaton, the list goes on.

So, even if we are not completely correct about Gravity, since it is not reconcilable with our other major theories, QFT and the Standard Model, and new theory of gravity must at least make those same predictions and reduce to newtonian gravity at the correct reference frames, and since the conservation of angular momentum is part of newtonian gravity, and therefore things closer to the center of mass of a galaxy should be rotating faster, which they experimentally are not, dark matter should also be a part of any new theory of gravity.

>>7449803
Further, good theories use mathematics to make predictions of new particles before they are discovered regularly throughout history. Dirac predicted the positron, and it took 5 years to verify, but that is a "lower" energy particle.

>>7449796
It's probably just another universe bleeding through

>>7449803
>General Relativity, and by extension Newtonian Gravity, are extremely correct though.
Phlogiston theory was a better performing, more consistent, and more mature theory than Lavosier's oxygen theory, and when you actually dig down into it Lavosier was kind of a nutcase and his theory was ridiculous.

There's plenty of cases in history where well-performing theories were abandoned, justifiably so in hindsight. Being well-performing is not in and of itself sufficient justification to prefer it to other theories.

>>7449866
Phlogiston didn't have an incredible amount of mathematical back up and experimental results.

That is what it comes down to, we do experiments, and build mathematical models to fit those results. Whichever models fit them best are accepted, the rest are discarded.

Conservation of Angular momentum is easily tested on a merry-go-round, or anything else that is spinning. And it must be a part of any mathematical theory of gravity we come up with, because it is experimentally true. That galaxies don't seem to obey it requires explaination regardless of everything else.

>>7449796
the fabric of space time is "dark matter"
our reality is two different universes
slightly out of phase with each other.
that overlap and can interact with each other

A "dimension" is in actuality a 2 dimensional brane
that can exist as either a brane
or can be rolled into a string.
Branes and strings can attach to other branes and strings
or can form a loop with themselves.
these branes are the basic building blocks
of the matrix of space time
and quantum manifolds of subatomic particles

Space time is composed of 3 Spacial dimensions
and 2 Temporal Dimensions
this is evidenced by the fact that science has documented
quantum wave effects in particle experiments
which is evidence of a 5th dimensional Spacetime.

what we call particles are actually 6 dimensional manifolds
composed of 6 Quantum dimensional branes
that create all the different particles that make up matter.

trying to mix space time and quantum particles
is like trying to mix oil and water
they repel each other.

in the act of repelling each other the branes of spacetime go taut
and a resonance starts to build up in the brane and propagates along the matrix
resonance attracts resonance and causes force feedback
pulling particles towards other particles
this resonance is Gravity
and the Double conversion resulting in a weaker resonance effect
is why gravity is the weakest of the fundamental forces.

>>7449901
>This is what popsci fans actually believe

>>7449909
Actually it's my own personal theory of gravity.
100% original

>>7449796
>>7449816
pic related, it's the dark lord's answer bleeding through

>>7449796
That's why a lot of peole have worked, and some are still working, on modifications of gravity. However, as far as I know, no such a model has been presented yet that explains all the things that the Dark Matter hypothesis does. Or, rather: they can explain many things, but eventually there are always situations (like the Bullet Cluster, if I'm not wrong) where they need at least some Dark Matter.

So, yes, of course we have tried to have an alternative explanation to all those problems that doesn't involve Dark Matter, but we haven't found one yet.

This *doesn't* mean that the Dark Matter scenario is necessarily true, but most of the community is pretty convinced of it because of the overwhelming amount of evidence there is (across many orders of magnitude, also).

what is the most accredited option regarding what composes dark matter?

a new kind of neutrinos?

>>7449796
Has /sci/ really not found Moshe Carmeli yet? His equations regarding the expansion of the universe can be measured, and do not rely on any fudge factors like "dark matter" or "dark energy".

>>7449898
>Phlogiston didn't have an incredible amount of mathematical back up and experimental results.
Yes it did. It was a well-performing theory that satisfactorily explained and predicted many chemical reactions.

It was wrong, but it worked.

>>7449950
They are "a new kind of neutrinos" in the sense that they should barely interact with us (i.e. the Standard Model particles), apart from gravitationally.

The sad truth is that we basically know nothing of what DM actually is. We have been able to put a lower and upper bound on its mass, with a range that spans almost 50 orders of magnitude (pic related).

Because of something called "the WIMP miracle", for many years now it has been widely believed that it would make sense to have DM in elementary particles form with a mass of some 100 GeV. This was ok also because people had a lot of faith in SUSY, which was expected to solve other problems by feeding us with a bunch of particles around that mass.

However, so far we haven't either observed Superymmetry nor any WIMP (Weakly Interacting Massive Particle) that could be DM, so...

In any case, I'm doing my Ph.D. in High Energy Phenomenology and I can tell you that most phycisists work in models where Dark Matter is some kind of elementary particle. It might be something more exotic, of very big size, but most models for the moment assume that, as you say, are "some kind of neutrinos".

>>7449953
>Implying muh space-velocity isn't just an assertion to remove both dark matter and dark energy.

You do realise that the existence of a 5th macroscopic dimension is a much larger, and much more revolutionary than dark matter/energy, right?

>>7449972

thanks for the informative response mate

also what is the role that dark matter could have had during the Big Bang?

>>7449901
Nice poem.

>>7449963
>Yes it did.

Not really, it was more of an ad hoc justification for experimental results, but it couldn't predict those results beforehand, at least not with any consistency. And then when Magnesium was found to have gained mass on combustion...well the rest is history.

>>7449796
Yes. Specifically, we are wrong about inertia. I will let you know when I finish my PhD thesis.

>>7449796

I've got my money on a mechanical interpretation of gravity. There are several and some are explored here:

https://en.m.wikipedia.org/wiki/Mechanical_explanations_of_gravitation

To my small mind, there appears to be an abundance of observations that fit well with an aetheric model of the universe - eg. Space having properties, light travelling as a wave in space (something that all other types of waves require is a medium, why not light too?), etc.

>>7449972
>They are "a new kind of neutrinos" in the sense that they should barely interact with us
we have detected neutrinos though even if the interaction is small. Imagine how small it must be for us to not have detected dark matter. Maybe it doesn't even interact at all besides gravitation

>>7449796

The issue is that there's not really any hint of where we're wrong about Gravity that would predict everything speeding up. Any theory that would replace Gravity would have to explain the same phenomena that are experimentally verified while also taking into account dark matter.

The other issue with dark matter is that it's gravity lensing had been directly observed in galaxies and is actually, factually there. It's not a mathmatical problem but an observed one

This must be the least amount of shitposting I've seen on /sci/. Good job all

>>7450001
Anon, pls don't exhume the aether. I promise you there's nothing new to find there.

>>7449998
>ad hoc justification for experimental results
many theories with predictability have begun that way though. this one just didn't pan out

>>7450001
Look up "flowing space" or the "river model of black holes" (actually it applies to any mass). This is the answer you've been looking for.

>>7450008
But then it isn't a theory. So things that eventually grow into theories might start with phenomenological rules-of-thumb, but the point is these rules must still be able to predict some out comes, phlogiston couldn't do that. And this is my point, it was used to justify results after experiments have been preformed, as such it could be used to justify practically any result, except when the chemists of the day found that some substances would gain mass on combustion, the exact opposite of how it should work.

>>7450016
>except when the chemists of the day found that some substances would gain mass on combustion
if it is as you say, then they would have tried to justify that too, attribute some property to those substances that makes them different from others, ad hoc as you say.

>>7449998
Yes, phologiston theory did reach a point where it became a system of ad hoc modifications, but that wasn't always the case. For a time, it did a pretty good job of describing combustion and (aside from the weight issue) oxidation/reduction of metals. Oxygen theory was just as full of holes at the time, too. Caloric was just as silly an idea as phologiston, and the early theories of the functions of acids was just dumb.

Besides, all theories start out as explanations of a jumble observations. If we discounted theories on that basis we'd have nothing left.

>>7450022
nevermind, just read that they did.

>>7449986
It effectively does both, and exposes them for the fudge factors that they are.

When theories can be measured, and predictive, they have standing. When theories rely on imaginary things, they do not have standing.

It's really not that difficult. As the objects in the universe are moving away from us, so too is space itself.

>The idea that the progress of the phlogiston program ended in 1770 (while the oxygen program continued in its smooth progress) is contradicted by Musgrave’s own statements earlier in the paper (p. 199): “While Lavoisier was failing, Priestley was having great success with the 1766 version of phlogistonism. . . . the most impressive experiment of all came in early 1783.” This was the confirmation of the phlogistonist prediction that calxes would be reduced to metals by heating in inflammable air. In order to sustain Musgrave’s thesis convincingly, we need to find successful novel predictions that Lavoisier’s research program made after the phlogiston program stopped making any, and that is 1783, not 1770. Where are these predictions? Are we thinking of the prediction that the oxidation of inflammable air (hydrogen) would
produce an acid? 13 Or the prediction that muriatic (hydrochloric) acid would be decomposed into oxygen and the “muriatic radical”?

>>7450002
Expermients have put bounds (on some certain range of masses) on how small the interaction with nuclei (for example) should be, so well, we don't need to imagine: we know it has to be fucking small.

Technically yes, you could say it might not interact at all with the Standard Model. The argument most people use not to work in this direction is because it's a Scientific dead-end: if it doesn't interact in any way, we will never detect it through experiment, so we would be done here as far as Science is concerned. Since we like to make predictions that can be tested, all models of DM allow for some interaction with the SM.

>>7449990

I know almost nothing about Cosmology so I can't tell you a lot. In any case, nowadays more accepted paradigm in Cosmology is what is called Inflation. This assumes that (very) shortly after the Big Bang, the Universe went through a period of extremely fast expansion. It's not easy to explain, but essentially anything that happened before inflation (between the Big Bang and the beginning of inflation) is irrelevant.

So, well, I guess one could translate the answer to "what role had Dark Matter during or right after inflation?". Well, not much; for a long cosmological time, Dark Matter is not different from the rest of matter, at least for cosmological purposes.

It is however true that, at later periods of the Universe, Dark Matter is essential to understand the structure of the Universe.

So, well, tl;dr: maybe not at the very beggining of time, but for sure the Universe wouldn't look at all like it does without DM.

>>7449953
Serious question: what's your level of education in Physics? Not saying it's low, I'm just curious.

Dark matter and dark energy have terrible names, and maybe they are not the most beautiful and elegant ideas in the History of Physics, but right now are regarded by the majority of the community as the most possible hypothesis to explain a shitload of things.

Well, at least for sure Dark Matter. To be honest, we know even less about Dark Energy, but still.

>>7450036
>all models of DM allow for some interaction with the SM.
what if we detect them only through gravitational wave detectors?

>>7450042
Gravitational waves experiments are really fucking hard. We are investing a lot of money in direct detection experiments, but they're hard, and we'll be happy if we measure *any* kind of gravitational waves. Even detecting an event that released a massive amount of gravitational waves (i.e. a supernova, etc) is hard to detect, let alone detect via gravitational waves the dark matter that we think permeates almost everything around us.

So, yes, of course, that is hard doesn't mean that it's false, but in general people working on DM want to propose candidates that could be measured in some way or another in a realistic way.

Life is hard.

>>7450048
so you're basically saying
>maybe we'll consider the possibility once we've detected gravitational waves first

>>7450062
I honestly would have to think of how exactly to detect DM via gravitational waves, but well, yes, if at some point we're able to detect them and have nice spectrums, then I'm sure people will start considering, if it makes sense. Or, rather, probably if there's an interesting way to do it people have already written those papers and are waiting, but nothing that I know about, sorry.

>>7450040
>we know even less about dark energy

I disagree. General Relativity had the cosmological constant built in. Quantum Mechanics gives a reason for the vacuum to have a non-zero energy (though QM's prediction is the worst in physics ever, there is at least a reason for the energy to be there.) Further, the inflationary model built off of the cosmological constant existing has matched very well with current CMB spectrum data, with dark matter factored in. Calling it "dark energy" still is a bit misleading. It's the cosmological constant, we've known it can exist since the early 1900s, we've experimentally verified it's existance, and it's fitting other models we're making. What we don't know is why it is the number it is, much like we don't know why the coupling constant of electrodynamics (the charge of the electron) is what it is.

Dark matter was invented to explain how fast the galaxies were rotating. That is, they were rotating faster than predicted, and the only way of explaining this speed was extra matter.

What's really going on here is that our model of the universe and how it's evolved is fundamentally wrong. That's not too big of a deal - this is science, we can get it right. Dark matter is an attempt to get it right.

The thing is, when you add more matter, the new model predicts the speed of galactic rotation pretty well. Therefore, either our understanding of the mass of various particles is wrong, or there's a bunch of matter floating around we can't see.

There are other reasons why people go with the dark matter theory. Have you heard of WIMPS, and primordial black holes? Well, some people think that the extra matter is bound up in a mass of black holes that exist beyond the borders of the galaxies. Recent evidence of an ultra-pressurized substance in inter-galactic space supports this notion.

Also, we would interact with this matter. A tiny black hole - like the kind that would compose this inter-galactic dark matter - could drift right through Earth undetected. But it would interact with particles on a very small scale.

>>7450040
And again I will refer you to Moshe Carmeli, whose work in this field has demonstrated that there is no need to speculate about the existence of "dark matter" and "dark energies" to explain observed phenomenon.

"I think what the mob thinks" is why science is always wrong.

>>7449796
>dark matter

more like 'doesn't matter', am i right?

>>7450090
Again, read some of the word done by Moshe Carmeli whose equations explain the observed phenomenon without the invention of fictitious dark matter/energy.

How "dark matter" and "dark energy" pass the laugh test is beyond me. Can't you tell they're fake just by the nomenclature?

serious question
when did moshe carmeli become a meme on here? I'm thinking recently

>>7450103
>invention of fictitious dark matter/energy.

This is very true, it just requires the invention of a completely new macroscopic dimension, yep, Carmeli's theory is clearly simpler and requires fewer assumptions then Lambda-CDM.

>>7450103
>Can't you tell they're fake just by the nomenclature?
what's the name of this science?

I know people are always trying to reconcile quantum mechanics and gravity to get 1000 nobel prizes, but what happens if you actually scale up quantum mechanics to the macroscopic world? Do you just get no gravity at all?

>>7449796
Gravity doesn't exist as an entity, it's more of a result of matter occupying space, where larger, denser amounts of matter will have a stronger pull because they occupy more space.

Gravitons don't exist and this model of gravity works in line with the fact that gravity becomes so miniscule that once you get down to a small enough size, it becomes a non-factor in equations.

>>7450142
>but what happens if you actually scale up quantum mechanics to the macroscopic world?

If only it was so simple, unfortunately you can't just scale QM like that. In a certain sense there's a disconnect between the classical and quantum world's at a very fundamental level, you see the classical word is deterministic, so it will always follow a certain set of rules, slightly more formally in classic mechanics motion is described by differential equations that will always yield the same conclusions. In Quantum mechanics it's probabilistic, so say you want to measure the distance of an electron from the nucleus then all QM can tell you is that, given a large ensemble of hydrogen atoms, the most probable place to find the electron is three halves the Bohr radius. However it's important to realise that you'll find the electron in different positions upon different observations, even if you have your atoms in identical conditions.

>>7449796
>I was thinkin of this the other day
HERE'S THE ANSWER OP!

In open space the massing of photons creates a lightning rod style slipstream of potential energy that does fucky stuff with space

That's what's happening at the edge of the universe and is what we consider dark matter

#soberperspective.jpg

>>7450158
That being said I'm an M theory fan and would go as far to say as this is what is propelling the density of mass

>>7450164
matter*

wow a thread on /sci/ talking about science

what's going on

>>7449796
In the Bullet Cluster, a collision between two galaxy clusters appears to have caused a separation of dark matter and baryonic matter. X-ray observations show that much of the baryonic matter (in the form of 107–108 Kelvin[51] gas or plasma) in the system is concentrated in the center of the system. Electromagnetic interactions between passing gas particles caused them to slow down and settle near the point of impact. However, weak gravitational lensing observations of the same system show that much of the mass resides outside of the central region of baryonic gas. Because dark matter does not interact by electromagnetic forces, it would not have been slowed in the same way as the X-ray visible gas, so the dark matter components of the two clusters passed through each other without slowing down substantially. This accounts for the separation. Unlike the galactic rotation curves, /////this evidence for dark matter is independent of the details of Newtonian gravity,///// so it is claimed to be direct evidence of the existence of dark matter.[51]

Just to clarify for the cheap seats, dark matter is clumpy throughout the universe, right? It is in some places and not others, and denser in some places and thinner in others.

On the other hand, dark energy is uniform throughout all of space, meaning I contain a very tiny amount of dark energy (something on the order of 7.92e−26 grams) and a similarly tiny amount is floating around in the space in front of me. Right?

>>7449796
>Isn't it much more likely that we're just wrong about gravity as opposed to 98% of existence being composed of something we can neither sense or interact with ?

Not really. Attempts to form a Modified Newtonian Dynamics (MOND) keeps running headfirst into various walls that arise when you try altering such basic physical laws to make them fit.

There was no particular reason why (to use an analogy) the loudest men in your town are the only men in your town. In other words, there's no particular reason why the most visible matter was the only matter.

>>7450103
Wrong. His model has never explained the expansion history of the universe probed in BAO or the CMB, not to mention dozens of other tests. It doesn't actually explain dark matter, it derives the Tully fisher relation, which is an in exact relation in observations. He derives it exactly, that's wrong. No explanation for all the other evidence. No attempt to explain dark energy so far as I can see.

Alternative models are fun but don't pretend you know better than cosmologists because you've heard of something.

>>7450122
Fewer assumptions is great but only if you can actually explain the observations. It doesn't. LambdaCDM doesn't exist because people love it, quite the opposite, it only exists because it's accurate.

>>7450477
>Fewer assumptions is great...

I was being sarcastic anon.

>>7450285
Dark matter is clumpy just like regular matter, not as clumpy because there are no hydrodynamic forces.

Dark energy in it's simplest mode, a cosmological constant, is constant thought the universe. Other models are not. Dark energy isn't necessarily a thing, it could be that empty space has an energy density or that gravity is modified on very large scales. Dark energy unlike dark matter is a broad class of models.

>>7450484
Sorry, skimmed. But it is true. Even inventing a new dimension all that really matters in a like for like Bayesian comparison is your number of free parameters. LambdaCDM has quite a lot but explains many observations. His model does not.

i have the theory of everything. >>7450482

>>7450492
Fair enough.