/sci/ - Science & Math

>>16252838
>Well supported Bodies of evidence for the Big bang?
The big bang predicted the CMB, and it's fluctuations (pic related), it predicted the abundance of light elements formed in the early universe, galaxy evolution and signatures of expansion.
All of these things were tests of the big bang, and more continue. Any alternative model should explain these observations, and eventually make novel testable predictions. The big bang already did that, multiple times.

>It's just shadows
Says the person who definitely knows for sure how the universe really works, god must have told him. It is incredible how delusional people are while being completely ignorant of cosmology.

>>14538611
>It would be hilarious if dark matter turned out to be cold baryonic gas, behaving in a way that just eludes telescopic detection.
That doesn't fit the data. The primary arguments against baryonic dark matter is not the lack of detections from telescopes, it's cosmology. Both the abundances of light elements from primordial nucleosynthesis and the powerspectrum of the Cosmic Microwave Background are sensitive to the baryon density. Both give a consistent value, which is nowhere near high enough to explain all of dark matter with baryons. The CMB constrains both the baryon density and the total matter density, they cannot be forced to be equal without rewriting cosmology and possibly gravitation. Many have tried to do that and have failed. The Cold Dark Matter model doesn't just fit the CMB powerspectrum, it predicted it years in advance of measurements.

>>12648110
You conveniently ignored all the successful predictions of Cold Dark Matter, wouldn't want reality to get in the way of your shitty narrative. Models without dark matter have still not explained the statistics of the CMB, even decades after it was first measured. CDM predicted the form of these curves.

>make prediction on matter content in universe
This wasn't a prediction, it was a guess. None of the cosmological models which existed at the time had any way of predicting the amount of normal matter, neutrinos or anything else.

>>12648151
>Cosmological constant 2.0, some new concept that was introduced to fill in the holes in an existing theory.
The Cosmological Constant is constant of integration in the derivation of GR. You cannot just decide you don't want it. Assuming it is zero is an assumption.

>>12554224
It's been more than 20 years since standard theory correctly predicted the powerspectrum of the cosmic microwave background. 20 years later there are zero alternatives to dark matter that have even explained this data after the fact.

"Muh electrons" doesn't really cut it. If you really think you know better then pull your finger out of your ass and build a quantitative model.

>>12468039
>You haven't observed anything that confirms it though
What do you mean? Cold Dark Matter has made numerous successful predictions. Probably the most spectacular was the form of the power spectrum of the fluctuations in the Cosmic Microwave Background. Models without dark matter have still not explained these observations 15 years later, while DM predicted it.

>you have cosmological observations that are at odds with our understanding of a theory
Which observations are in conflict with Lambda CDM?

>Claiming that 'dark matter' can bridge this gap to be valid is not science
I don't think you understand. Dark matter is not some "god of the gaps" in cosmology. It is a very well defined model, which can be calculated and simulated in detail. This model makes predictions, and several have been confirmed.

>Precisely, just like physicists now assume what gravity is in order to justify dark matter.
Nope. GR (and classical) gravity faced numerous tests.

>The Big Bang is none of those things
Wrong. The big bang model has faced dozens of tests.

>>12245116
That's not how it happened, at all. People did consider alternative models where gravity or dynamics were modified, but these models have had far less predictive success. The smoking gun for dark matter cam in it's prediction of the statistics of the Cosmic Microwave Background, which independently measures the amount of normal matter and total matter. Dark matter models correctly predicted these features, and alternatives have still never explained this 2 decades later.
>Bad formulas that people refuse to admit are wrong.
There's nothing rational about assuming the universe must be dominated by stuff you can see today.

>>12131898
He can't. McCulloch is a crank. He claims his model can explain rotation curves of galaxies but his result is basically just MOND, which was known about for decades before. So his idea hasn't added anything new. He just backward engineered a model which was known to work quite well. The problem is there are many other probes of dark matter and McCulloch has no explanation for those, but he will wave his hands and tell you he can. MOND fails all large scale tests, it needs it's own dark matter in clusters.

One of the biggest pillars of evidence for dark matter is the statistics of the cosmic microwave background, standard theory predicted the form of the powerspectrum incredibly well. In standard theory these results show that the total matter in the universe is greater than the normal matter. MONDian predictions failed. You can't just remove dark matter and get the same prediction. I put this criticism to him on his blog all I got was some bullshit handwaving.

>>12002723
>Yes, the blackbody spectrum was certainly predicted. That's true but it's completely trivial.
It was not trivial. There were competing models which claimed the CMB had to be local radiation, these models failed to explain the backbody nature of the CMB. It's just simple history. Not every model agreed that it was backbody radiation.

>I do not think the scale of the angular features were predicted by anything other than random happenstance guessing before the measurements were made.
Not the scale, the form. As I said. These were not randomly parameterised models, that's utter bullshit. It was standard theory that predicted there would be peaks in the powerspectrum due to baryon acoustic oscillations.

https://arxiv.org/abs/astro-ph/9603033

They could not predict the scale because they didn't know the underlying cosmology. But the fact that the structure in the powerspectrum matched predictions was a huge success. The complex features of the powerspectra (see fig) were not just "guessed". The information in these curves is orders of magnitude more than the temperature and the absolute angular scale.

>, the angular feature scale, certainly not the multipole moments
The amplitudes of the multipole moments are the powerspectrum.

>I prefer not to kick the can down the inflation road and simply ask the direct question about thermal equilibrium.
Some might not like inflation but it doesn't change the fact that it is what explains the horizon problem in standard cosmology. People regularly ignore that inflation has already made a successful independent prediction, as I described previously.

>The scales are wrong depending on when thermal eq. ..
The scales are wrong because you just multiplied the age of the universe by 2, which is not how distances work.

>>11904465
It's easy to claim the universe is simple when you have never bothered to test your claims. It's literally just their idea of how the universe must be, they don't give a fuck about the data or reality. Standard cosmology predicted these curves, that's how real models work.

Inflation solved several problems, the flatness, the lack of monopoles, the horizon problem. But inflation also made predictions. Inflation also explains how the initial perturbations in the universe were generated.

But inflation also made predictions, it's prime prediction was that the scalar spectral index would be close to but less than 1. The scalar spectral index describes how the perturbations in the early universe change with scale. This can be tested by measurements of the Cosmic Microwave Background. Most recently Planck confirmed the scalar spectra index is less than 1 at over 6 sigma statistical significance.

Just like dark matter you're completely ignorant of the actual science. You're like an anti-vaxxer who thinks they know better than an entire field after 2 minutes on google.

>>9649193
>It is impossible to disprove something for which there is no real evidence.
Dark matter is a model, Cold Dark Matter is the standard model. Contrary to misconception CDM can't do whatever you need it do, it's statistical properties can be simulated and compared to observations. For example CDM predicted the statistics of the fluctuations in the cosmic microwave background (pic related). One can also find contradictions to CDM as people have been trying to for 20 years.

>In other words: the dark matter—which, putatively, dominates the galaxy’s total mass budget and determines V—somehow knows to distribute itself in a way that strictly respects the distribution of the normal matter in every galaxy.
Which has been matched in simulations. The Tully-Fisher relation is now understood in a dark matter context. Bear in mind it can match those observations at the same time as cosmological tests like the CMB, no alternative comes anywhere close.

>>9633271
>Unless it is observable and testable science should stfu.

Cold Dark Matter is testable. It has made dozens of successful predictions from the powerspectrum of the Cosmic Microwave Background to the one and two halo galaxy clustering. "Observable" is arbitrary. Quarks aren't directly observable too but they are a model, you can calculate very precisely what that model predicts and compare that to observations. CDM is exactly the same. It is testable and it is being tested.

Just because you're ignorant doesn't mean a field is flawed. Dark matter isn't "chaining the numbers". From simile initial conditions and gravity, cold dark matter tells you dark matter collapses to form halos, these halos have just the right slope to show why rotation curves flatten. There are no parameters to tune to do that. CDM can also be tested in dozens of other ones. For example predicting the statistics of the fluctuations in the cosmic microwave background, the ratio between odd and even peaks tells you about dark matter. CDM correctly predicted these observations, no dark matter free model has explain this. Dark matter also predicted that the signature of dark matter halos should be imprinted on how galaxies cluster, long before this prediction was confirmed.

>>9456565
MOND doesn't explain anything. MOND prescribes a modification to Newtonian gravity. It doesn't tell you why that occurs, or even what form it should take. It also doesn't match observations of galaxy clusters or cosmology, cold dark matter does. It utterly failed in it's predictions of the cosmic microwave background, so it's proponents just gave up. MOND is pretty much dead.

>>9427000
It is what Alfven himself claimed. Plasma cosmology today however is dead, no one is actively trying to reconcile it with the CMB. Plasma cosmology is not capable of explaining the perturbations observed on the CMB, there is no model for them so there is no model of anomalies. Saying plasma cosmology could explain it is ass-backwards because plasma cosmology can't explain the rest of the CMB, which standard cosmology predicted (pic related)

>all plasma in the universe has a hand in producing the microwave background radiation
The problem is a) its almost impossible to accidentally make a perfect black body by accident and b) it's very hard to get the isotropy to the extremely high level observed. Secondly if it was just produced by matter you would expect extremely strong correlations between the primary anisotropy and galaxies, this is not observed.

>heavily depends upon unprovable assumptions, such as singularities.

Wrong. The modern big bang theory doesn't make any claim about a singularity. The earliest epochs people talk about is inflation, note that inflation begins when the universe is a finite size and not a singularity. Anything before that is currently speculation and there is no reason to suggest a singularity is needed. Without a model of quantum gravity there is no sense in trying to describe earlier times.

The big bang is incredibly well tested, take for example this, the Cosmic Microwave Background power spectrum. It was predicted with standard cosmology, inflation and a little acoustic physics.

Come back when you can explain the statistics of the Cosmic Microwave Background (pic related) without dark matter.

>>9304098
>MACHOs so far have accounted for about half (30% according to Wikipedia)
That's not even close to true. The current upper limit from microlensing surveys is 8%, that's a maximum value, not a detection.

https://arxiv.org/abs/astro-ph/0607207

>maybe it's not some exotic WIMPs?
It's not believed to be normal matter because of two independent lines of evidence. Firstly primordial nucleosynthesis fails wildly to match the observed abundances of elements if one tries to force all matter to be baryonic matter. Secondly observatons of the cosmic microwave background powerspectrum (pic related) are sensitive to both the normal baryonic matter and the total matter independently, you don't fit the data if you set them as equal. Something like a neutron star is made of normal matter which would have been present in the early universe and contribute to both these tests.

>>8859947
> A prediction is when you conclude something that you did not know
Like the scalar spectral index being less than one. That was a prediction of inflation which was confirmed later.

>Still background noises are everywhere and can be produced by literally anything
Yes, literally anything can produce these beautifully clustered data that has an SED which is a blackbody as well as has been measured. Bullshit. These spectra are not random. Standard cosmology predicted the features of the power spectrum before it was measured, a prediction. Come back when you have a physical model that can fit this.

>3-Abundance of less massibe elements. It just makes sense to be like this when you take into cosideration that to form a more massive element you have to fuse elements of lower mass. The tendency will always be to have less massive elements. We know that those fussions already happen on stars, so there is no reason for the big bang to have ever happened.
You don't even know what the fuck you're talking about. Standard cosmology predicts the relative abundances of the light elements in primordial matter. That is a prediction which is still being tested as better measurements are made of different isotopes.

>>8326374
>>8326359
>all experimental "evidence" of the more dubious claims find linear regressions in a cloud of random data points

If you think this is just "a cloud of random data points" then you're quite insane.

>>8133696
Can "god's will" predict the powerspectrum? No.

Don't confuse a testable model with a handwave.

The CMB power spectrum and the abundance of primordial elements. The later constrains the density of normal matter much lower than cosmology requires for the total matter. The CMB power spectrum is sensitive to both the amount of normal matter and total matter independently.

>>7930140
There's not "fudging numbers". LambdaCDM is a new model, tested against new observation such as the BAO peak in the modern universe and CMB lensing. That is the very basis of science. Build a new hypothesis and test it.

But no, your ignorant prejudice definitely has more merit observational tests.

>>7596840
This. Your opinion of a model is completely fucking irreverent. If you knew anything about modern cosmology you wouldn't make fun of LambdaCDM due to it's tremendous observational success despite an army of people searching for alternatives and inconsistencies.

The day you produce a cosmology which explains not only the formation of structure and dynamics in the universe but can reproduce this fit and a dozen more like it is the day you won't call DE/DM bullshit. You won't because you would cease to be an ignorant fucktard.