# Dark Matter? Now the universe is too bright



## Brian G Turner (Jun 29, 2015)

New Scientist reports on a study that there's more UV light in the modern universe than can be accounted for:
http://www.newscientist.com/article...ing-the-universe-too-bright.html#.VZD7xUYhEuc



> there's even a chance something is wrong with our basic understanding of hydrogen.


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## Vertigo (Jun 29, 2015)

I thought the following statement was particularly interesting:



> Strangely, their simulations also show that, for the early, more distant universe, UV sources and ionised gas match up perfectly, suggesting something has changed with time (_Astrophysical Journal Letters_, doi.org/tqm).


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## Ray McCarthy (Jun 29, 2015)

Ha Ha. 

I don't believe in Dark Energy and Dark Matter. I suspect most Scientists in the field don't either, both only exist to try and fudge between observation and the best theories.


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## Vertigo (Jun 29, 2015)

Of course they don't. Every scientist I have seen talking about them states that they are place holders until they can figure out what they are. Isn't that what any theory is until it is proven? It's just possible that this observation may help shed some more light on that.


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## hardsciencefanagain (Jun 29, 2015)

let's await some results from
FERMI
HAWC
VERITAS
ATC
first


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## Mirannan (Jul 1, 2015)

Dark energy - maybe. Dark matter, however, almost certainly exists in some form - the original work on orbital speeds in galaxies, and gravitational lensing by something invisible, supports that. Especially as the mathematics of the Big Bang apparently preclude the missing mass being baryonic, or even having been baryonic once - the latter precluding large numbers of black holes.

It's also impossible that the missing mass is in really small black holes - say asteroidal mass or so, which could have been formed by inhomogenities in the early Universe - because if they existed there would be rather frequent flashes of high-energy gamma rays caused by the holes evaporating.


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## JoanDrake (Jul 2, 2015)

Is dark matter/energy supposed to be with us or somewhere out in the remote Universe? If it's with us I wonder if it might be the source of whatever "real" magic and/or psychic phenomena might exist.


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## Venusian Broon (Jul 2, 2015)

JoanDrake said:


> Is dark matter/energy supposed to be with us or somewhere out in the remote Universe? If it's with us I wonder if it might be the source of whatever "real" magic and/or psychic phenomena might exist.



Simple answer: It's all about us, both of them, but no I can't see how they could possible interact with creatures like us who are so small. 

Dark matter - hypothesised because galaxies spin at the wrong velocity for the visible matter that can be seen and estimated. Adding dark matter is one way of returning the physical observation with how we think physics should work. (For the record there are other hypothesis that do not use dark matter)

Dark energy - the universe is accelerating its expansion over time, something that we never expected, thus dark energy is hypothesised (as a Vertigo states, a placeholder) to be the 'cause' of this expansion.

Both items are given the title 'Dark' because we've never seen or been able to interact with either of these concepts and are therefore mysterious to us. If we weren't studying the vast cosmos we would not know of their existence nor have picked up their slight interactions with the universe. We do not have anything on the scale of humans or planets that requires extra mass as an explanation, it is something that only impacts noticeably very massive objects like galaxies. And the expansion of the universe is again only noticeable for us when we peer at galaxies a great distance away. 

Both concepts are useless at explaining how to magically bend spoons, read minds or contact the dead etc...


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## Ray McCarthy (Jul 2, 2015)

JoanDrake said:


> Is dark matter/energy supposed to be with us


Yes, but not really, it's a temporary "fudge" to make current theory and observations agree. The ONLY evidence for "dark matter" or "dark energy" is simply the observations don't match our theory. There is no actual direct evidence for either by observation, nor any inherent suggestion of them in the theories. So no proof they exist at all or suggestion what they might be.


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## Ray McCarthy (Jul 2, 2015)

Venusian Broon said:


> bend spoons, read minds or contact the dead etc.


In every properly examined case, these have been shown to be fraudulent, just Stage Magician type tricks. 

http://web.randi.org/about1.html


> The JREF offers a still-unclaimed million-dollar reward for anyone who can produce evidence of paranormal abilities under controlled conditions ...
> ...  help to create a world where everyone has access to the tools of science and critical thinking, and charlatans can’t get rich by deceiving people.


Yuri Geller for instance is a 2nd rate Stage Magician that decided he could make more money from the gullible. He's been exposed many times.

I love to have magic, paranormal, psychic  etc in my own stories and read stories with them. But it's just entertainment, not real.


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## Brian G Turner (Jul 2, 2015)

Venusian Broon said:


> Dark energy - the universe is accelerating its expansion over time, something that we never expected, thus dark energy is hypothesised



I still find the reasoning mad - observe a number of Type 1A supernovas, expecting them to have the same observed brightness. But they don't. Instead of questioning assumptions, or exploring possibility of something between observer and object, instead suggest completely new concept of energy with no theoretical basis.

I find that a mad way to do physics!


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## Venusian Broon (Jul 2, 2015)

Brian Turner said:


> I still find the reasoning mad - observe a number of Type 1A supernovas, expecting them to have the same observed brightness. But they don't. Instead of questioning assumptions, or exploring possibility of something between observer and object, instead suggest completely new concept of energy with no theoretical basis.
> 
> I find that a mad way to do physics!



It is how physics is done, really, you take a hypothesis from a set of experimental data, then you try to 1) work out the properties of this thing from the observations 2) design better experiments to measure and probe it. 3) Do these experiments come back with something, yes - you are onto something, no - well that explanation does not seem to work.

For example, Dirac took the experimentally tested Quantum mechanics, applied special relativity to it and from his calculations came to the conclusion that anti-electrons should be possible. It took a some years, but eventually someone came along and actually observed these particles for the first time.

Dark energy is just a hypothesis, albeit a dark sexy one that seems to resonant with many, but merely a hypothesis. I think the problem is Brian, that we are just getting the summarised notes that sell the story - I'd be totally surprised if they haven't thought very hard about all the other possibilities before deciding that Dark Energy seemed the best way to explain their observations. It should be noted that extraordinary claims such as the one about the increasing acceleration of the expansion of the universe would have gone under extreme scrutiny from the cosmologist community - that it seems to be the preferred 'explanation'  now although it is really a bit pants suggest to me that it passed that hurdle and therefore there must be good reasons why some of the ideas that you've stated just don't work.

EDIT - the thing that makes me baulk at Dark Energy is I suppose it's such an 'empty' idea. So nebulous and unconnected with anything bar this one observation, no theoretical underpinning, nothing that fits it into a 'grand scheme of things'...Dark matter on the other hand, I can at least imagine there _might_ be particles floating about the universe that only weakly interact with ordinary matter that are a right pain to try and detect.


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## Mirannan (Jul 2, 2015)

Regarding the business of type IA supernovas, they are brighter than expected. Which neatly gets rid of things like dimming by dust as an explanation. So two possibilities remain; dark energy (which as rightly said, really means "something that's pulling apart the universe and we don't understand it") or the laws of physics being different in the early universe, thus changing the brightness of these supernovas - whose physics is fairly well understood.

Obviously, either of those requires an extension to the laws of physics we already know.

As for dark matter, there are quite a lot of candidates for its composition which have in common that they are so-far-unobserved particles that form part of extensions to current theory (for example supersymmetry) and would, if any of these theories are correct, interact very weakly with normal matter at reasonable energies. (It's going to be a very long time, if ever, before we have the technology to accelerate particles to GUT energy levels!)


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## Brian G Turner (Jul 3, 2015)

Ray McCarthy said:


> In every properly examined case, these have been shown to be fraudulent, just Stage Magician type tricks.



A negative result doesn't infer the non-existence of something, merely that it wasn't found. I doubt that James Randi has been able to demonstrate in the lab the moment people fall in love, or someone being inspired to create a masterful work of art.


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## Ray McCarthy (Jul 3, 2015)

Brian Turner said:


> I doubt that James Randi has been able to demonstrate


I don't think he tried.
The point is that while some psychics, mediums etc really believe the stuff, the majority are deliberate frauds. Houdini as well exposed a lot. They are deliberately using Stage Magician tricks. Hence people like Houdini and Randi have known how to devise experiments to catch them out even when scientists have been fooled by poorly designed experiments.

Randi's foundation wants people to use scientific method and scepticism, not accept claims at face value. 


Brian Turner said:


> A negative result doesn't infer the non-existence of something


True, but in the case I'm talking about people are making claims something exists (homoeopathy, telepathy, talking to dead, remote viewing, dowsing etc) and results of properly done experiments match placebo or chance.

They aren't talking about scientific proof of love, justice, mercy, hate, creativity, inspiration etc. The fact is that if the phenomena above did exist vs number of supposed practitioners, there WOULD be evidence. The results are often "positive" not negative. Discovering how the fraud or deception is done is a positive result.

Placebo and Nocebo are positive results too. That's outcomes different from doing nothing or chance. We don't know what causes Placebo and Nocebo effects, but if you believe something will harm you, in significant number of cases it does, and if you think it will help, it may do, though there is no good reason. Hence doctors are being warned to be careful with describing prognosis and describing efficacy of treatments. Certainly there is a mystery there.


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## Venusian Broon (Jul 3, 2015)

Brian Turner said:


> A negative result doesn't infer the non-existence of something, merely that it wasn't found. I doubt that James Randi has been able to demonstrate in the lab the moment people fall in love, or someone being inspired to create a masterful work of art.



However no one is making extraordinary claims about falling in love that involve psychic forces, and I don't think Randi would claim either of the two situations above don't exist  (Particularly both of them, if you've seen the recent documentary on him on BBC4, I was almost a little heartbroken to see him on the day when he might have lost his lover [and artist!].)

I'm not a great Randi fan - he comes across as a hard-bitten skeptic and cantankerous - but he does focus on going after those that deliberately lie and manipulate the public for personal gain through such lies. Uri Geller is getting better in his old age, apparently he no longer describes himself as a psychic and he no longer tries to get university professors test his psychic abilities...

Oh and what Ray says, as he posted it before I posted this


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## hardsciencefanagain (Jul 3, 2015)

If i understand it correctly,the problem is benchmarking.
Hadronization of strongly interacting particles,decay of charged leptons,inverse Compton scattering of light,and Bremsstrahlung make it very hard to gauge energetic phenomena in the universe.


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## Ray McCarthy (Jul 3, 2015)

Venusian Broon said:


> not a great Randi fan - he comes across as a hard-bitten skeptic and cantankerous - but he does focus on going after those that deliberately lie and manipulate the public for personal gain


Agree totally.



hardsciencefanagain said:


> If i understand it correctly,the problem is benchmarking.


I thought the problem was discrepancy between existing theories and observations.


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