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Could dark matter not exist?

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Re: Could dark matter not exist?

#31

Post by kleer001 »

smil wrote: post #8
graycat wrote: post #2

Something has orbits around galaxies failing to follow the law of gravity from ordinary matter. The orbits are as if there there is some more mass with gravity, mass that doesn't interact with light. Something is in/near galaxies is bending light as if there were more mass there than there is from just ordinary matter. So, for that extra mass, call it dark matter . Seems simple enough. "Flaw in the theory of gravity?…

Exactly. Dark matter and dark energy is just a symptom of the standard model of physics being incorrect. >Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.[2][3]…

> Science is literally religious faith.

No it isn't. Not by a long shot. Faith requires that you confabulate to a reach a certain cognitive destination. Science only allows models that conform to reality upon repeated testing.

Re: Could dark matter not exist?

#32

Post by GFK_of_xmaspast »

GFK_of_xmaspast wrote: post #29
HillOBeans wrote: post #18

For those who are interested, physicist John Hartnett has developed a model that does not require dark matter. His work builds on that of Moshe Carmeli, who published "Cosmological Special Relativity". Hartnett's book is "Starlight, Time, and the New Physics" ISBN 978-0-949906-68-7. Disclaimer: I am not a physicist, and the math is way over my head, so I cannot double-check it. Hartnett has not made much, if any, hea…

Look at the first graph in the "My own analysis" section here: http://johnhartnett.org/2015/03/29/the-coming-long-dark-wint... and laugh.

Oh he's also an islamophobe: http://johnhartnett.org/2014/03/29/cancer-in-our-society/

" We see the creep of discrimination (against Christian doctrines) slowly entering society in appeasement to the Islamic agenda. The mainstream church works against the true gospel. They side with the atheist and Islamic agendas. The progressives (who don’t like the label of ‘the Left’) inexorably have taken over the West. Starting with atheistic Karl Marx, then the true communists using the socialists as useful idiots they have persuaded the democracies founded on Judeo-Christian values to forfeit those values and adopt those that God hates. It all started in the beginning. There is nothing new under the sun (Ecclesiastes 1:4-11)."

Re: Could dark matter not exist?

#33

Post by dalke »

cristianpascu wrote: post #26
gnufied wrote: post #20

Earlier quoted context omitted.

Just read one of his articles from his Website. He mixes physics and mythology with impunity. No wonder, his theories are not taken seriously.

So, say, if someone comes to you with a clean demonstration of how and why something is happening in the world, people verify it and it proves correct, and (s)he says the idea was revealed while smoking pot in a mystical hotel in north canada, or france for that matter, you'd say no one should take the theory seriously? Good job!

I believe that gnufied is saying that this isn't a clean demonstration. If one paragraph of explanation is buried in 1,000 pages of dreck, then is the onus on the reader to find the nugget, or the author to emphasize the important part?

If you've ever hung around a physics or astrophysics department you'll find that a lot of people send in explanations of how modern science is wrong. For example, http://www.universetoday.com/108044/why-einstein-will-never-... comments:

> One of the benefits of being an astrophysicist is your weekly email from someone who claims to have “proven Einstein wrong”. These either contain no mathematical equations and use phrases such as “it is obvious that..”, or they are page after page of complex equations with dozens of scientific terms used in non-traditional ways. They all get deleted pretty quickly, not because astrophysicists are too indoctrinated in established theories, but because none of them acknowledge how theories get replaced.

Re: Could dark matter not exist?

#34

Post by GFK_of_xmaspast »

cristianpascu wrote: post #26
gnufied wrote: post #20

Earlier quoted context omitted.

Just read one of his articles from his Website. He mixes physics and mythology with impunity. No wonder, his theories are not taken seriously.

So, say, if someone comes to you with a clean demonstration of how and why something is happening in the world, people verify it and it proves correct, and (s)he says the idea was revealed while smoking pot in a mystical hotel in north canada, or france for that matter, you'd say no one should take the theory seriously? Good job!

Have you read this dude's posts. There's a big difference between Kerkule staring at the fireplace and stuff like this:

http://johnhartnett.org/2015/01/26/supernova-remnants-and-th...

Re: Could dark matter not exist?

#35

Post by deciplex »

jfoutz wrote: post #21
lordnacho wrote: post #4

It reads like a great example of how theory works. You have some evidence (old planets), and a model that predicts it well (Newton/Kepler). Then some new evidence comes in (Uranus), and the theory is almost right, but not quite. So we modify it a little, or we start searching for an extra mass to explain the error. Then some more experimental evidence comes in (galactic radial velocity), and we are thinking about mod…

Real science is ugly because there are a bunch of theories that kinda sorta fit, but not really well. I think Maxwell had something like 40 equations for electricity. Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges. The unknown edges are messy, but as competing theories get winnowed out, merged and refined they become clear and concise.

> Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges.

Ugh, and we just had this on here the other day: https://news.ycombinator.com/item?id=9779206 :-)

Re: Could dark matter not exist?

#36

Post by dalke »

mixmastamyk wrote: post #14
aetherson wrote: post #9

Earlier quoted context omitted.

There'd have to be so much of it that we'd see it. There's way more dark matter than normal matter in the universe (stipulating that dark matter theories as we currently understand them are at a coarse level correct). If it were "dark dust," there would be enough of it that we would be able to detect it through means other than gravitational ones.

Thanks. Given that the Oort cloud is very sparse and we can't see it, and we can't (optically) see even the largest planets on other stars, why would we expect to be able to see it?

For what it's worth, https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla... is a list of the directly observed extrasolar planets.

Re: Could dark matter not exist?

#37

Post by deciplex »

cletus wrote: post #28

I'm no physicist but I've asked myself this question. It's a bit like string theory. String theory is a mathematical answer that solves some (all?) of the inconsistencies between quantum theory and gravity but has some implications that have no experimental evidence (eg extra dimensions). Dark matter always struck me as a kludge to explain the universe fit our model. There are many theories on it but no observed or e…

> There are many theories on it but no observed or experimental effects of dark matter to date.

FTFA:

> And most spectacularly, you get an entirely new prediction: that when you get two clusters of galaxies colliding, the gas inside should heat up, slow down and emit X-rays (in pink, above), while the mass that we can see through gravitational lensing (in blue, above) should follow the dark matter, and be displaced from the X-rays. This new prediction has been borne out observationally and held up over the past decade, a spectacular indirect confirmation of dark matter.

Re: Could dark matter not exist?

#38

Post by tjradcliffe »

cletus wrote: post #28

I'm no physicist but I've asked myself this question. It's a bit like string theory. String theory is a mathematical answer that solves some (all?) of the inconsistencies between quantum theory and gravity but has some implications that have no experimental evidence (eg extra dimensions). Dark matter always struck me as a kludge to explain the universe fit our model. There are many theories on it but no observed or e…

Dark matter is no more a kludge than phlogiston, or the lumineferous aether, or neutrinos. All of them were introduced as novel entities to explain experimental phenomena. The first two turn out not to exist, the latter does: http://www.tjradcliffe.com/?p=1801

Calling them kludges is to mistake the basic process of science for a hack.

There are any number of confirmatory observations that fit the dark matter model, just as there were any number of confirmatory observations that fit the neutrio model. It's just that we haven't observed any dark matter particle interactions directly, just as we hadn't observed any neutrino interactions directly before Reines' experiment.

It may be that dark matter turns out not to exist, and then we will know it was wrong. Until then it is perfectly ordinary science working in perfectly ordinary ways as it has been for over a century.

Re: Could dark matter not exist?

#39

Post by jfoutz »

deciplex wrote: post #35
jfoutz wrote: post #21

Earlier quoted context omitted.

Real science is ugly because there are a bunch of theories that kinda sorta fit, but not really well. I think Maxwell had something like 40 equations for electricity. Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges. The unknown edges are messy, but as competing theories get winnowed out, merged and refined they become clear and concise.

> Give it a hundred years and hundreds of thousands of grad student hours, and something quite clean emerges. Ugh, and we just had this on here the other day: https://news.ycombinator.com/item?id=9779206 :-)

I'll defer to your expert opinion of course, but it seems like faraday discovered some odd behavior in 1821, maxwell codified it in 1861. By 1884 Heaviside reformulated them into the modern form.

Perhaps 100 years is an exaggeration, but the point is it takes time to make sense of what the heck is going on.

Really, pick anything. someone notices something odd, tries to explain it. there are many many experiments. Someone really clever ties them together in a nice way. Someone else really clever cleans it up.

Einstein and general relativity is the only counterexample i can think of. But I'm pretty sure Poincare had a formulation of special relativity.

Re: Could dark matter not exist?

#40

Post by tjradcliffe »

mixmastamyk wrote: post #7

Interesting, I always thought of dark matter as just a lot of extra "dust", the dust that clumps to make the stars that make up the universe. The asteroid belt, the extra mass in our kuiper or oort clouds, etc. The dust that blocks parts of our view of the Milky way. This article (and others I'm now skimming) point out that dark matter needs other magical properties however. Why is that the case? Why does simple "dar…

There's nothing magical about the required properties, so I'm not sure why anyone would describe them that way. They are no different than the properties imputed to neutrinos or the aether: http://www.tjradcliffe.com/?p=1801

The important thing about extra-galactic dark matter is there is too much of it to be made of ordinary particles: protons and neutrons and electrons. We know how many ordinary nucleons there are because we have a pretty reasonable estimate of the primoridal ratio of hydrogen to helium. As the Big Bang cooled quarks eventually cooled down enough to make protons and neutrons. Free neutrons only live about fifteen minutes so they only had a short time to capture onto protons and make deuterium nuclei which could further colide to make helium. The ratio of He/H in the early universe is therefore a sensitive measure of the denisty of the universe at the time of nucleon condensation, and we know the radius from the temperature, so we can calculate the total number of particles. There aren't enough to make up extra-galactic dark matter. There are enough to make up galactic dark matter, so there may be two totally unrelated dark matter problems.

When physicists talk about "dark matter" we are sliding back and forth between meanings according to context, but this is all lost on outsiders, unfortunately. It's needlessly confusing, but unfortunately it's the way it is.

So amongst the perfectly ordinary, non-magical properties that extra-galactic dark matter has to have is to be something other then ordinary neutrons and protons. There are some other contraints on its various interaction strengths that come from the scale of galaxy formation and larger scale structures in the universe too. Again, these are perfectly ordinary properties, inferred based on the evidence in exactly the same way the properties of aether and neutrinos were.

Dark matter may or may not exist (neutrinos do, aether does not) but there is absolutely nothing out of the ordinary about it. It is just normal science doing what science normally does.

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