Scientist find Universe's missing mass - well most of it!

[g__day]

Amazing what you can find when you look in different places (or more specificly at high energy (Ha) wavelengths). So is this the dust bin for alot of dark energy scenarios?


http://worldofweirdthings.com/2010/03/24/newsflash-most-of-missing-universe-found/

The universe as we know it (http://worldofweirdthings.com/2009/12/19/across-the-universe-and-back-in-six-minutes/) is mostly empty, with light years separating most stars and great voids stretching for millions of light years between large galaxies. But there was also a major chunk of the universe missing, a chunk to the tune of 90% which physics said should be there and yet, no telescope could track it down. That is until the ESO’s giant telescope array in the Atacama desert of Chile flexed it’s 8.2 meter mirrors and found the swaths of missing galaxies about 10 billion light years away just by using a different wavelength. The problem was the gas composing the galaxies in question. Instead of just letting the light escape, it was absorbing the emissions for which astronomers look: the Lyman alpha lines generated when electrons shed some energy, emitting ultraviolet light in the process. When the first surveys of galaxies emitting Lyman alpha lines began, they were based on the idea that ionized hydrogen gas from new stars should be shining bright with a certain frequency of ultraviolet light and found that it was indeed the case. For just 10% of the galaxies they saw…
However, giant chunks of the universe don’t just go missing for no good reason, at least not as far as science is concerned. The problem was that survey teams before were looking for a hydrogen transition line between an electron’s second and first quantum states, or as the electrons were essentially grounding themselves. In the successful attempt to find the missing galaxies, astronomers looked for the Hα line, one energetic order higher. The light they observed came from electrons moving from their third energetic state to its second with quantum energies of approximately 1.9 electron volts from a very well studied area of the sky in which a swath of never before seen galaxies would be very obvious. When the sky lit up with galactic archipelagos, it was a pretty safe bet that the missing galaxies weren’t really missing or hidden behind some space-time manifold, but were out in plain sight. All we had to do was look with a different eye…
See: Hayes, M., et. al., (2010). Escape of five per cent of Lyman-α photons from high-redshift star-forming galaxies Nature, 464 (7288), 562-565 DOI: 10.1038/nature08881 (http://dx.doi.org/10.1038/nature08881)

[gary]

Thanks for the link.

[wasyoungonce]

Well this still would not account for the steady state rotational orbital velocity (http://en.wikipedia.org/wiki/Galaxy_rotation_curve) of stars within a galaxy. This can only really be accounted for by the cosmology standard model.

[Jarvamundo]

Umm wasn't this failure of the cosmology standard model predictions, why dark matter was invented (hypothesised) in the first place? using the words "only" and "really" is a bit of a stretch for this hypothetical matter solution.

yes - the macho men will not be happy with these developments

[wasyoungonce]

I believe the addition of dark energy with the dark matter model is the current working standard mode (http://en.wikipedia.org/wiki/Physical_cosmology)l.

[Jarvamundo]

containing 90%+ inferred hypotheticals
http://en.wikipedia.org/wiki/Dark_Matter_(disambiguation)


just a your "real" vs my "real" sorta thing... i think we know where this leads. both usual points have been made. I just believe we should be honest about the hypotheticals we have invoked when pronouncing our theory as "real".

[wasyoungonce]

I know the addition of dark matter & dark energy is very contentious. Call it a constant thrown into equations to make them work, if you will.

Throwing in of constants like this is a std scientific approach until that missing constant can be explained.

Can it be explained in the future...yes but it may take time and could we understand it...who knows.

[Nesti]

Did anyone attend the seminar at UWA by Dr Martin Hendry in Perth...about 18mths ago?

Why Are We Here? (http://www.news.uwa.edu.au/oct-2008/uwa-free-public-lecture-why-are-we-here)
Not only is the universe expanding but we believe the expansion to be accelerating - driven by a mysterious "dark energy" which challenges our ideas about gravity and the very nature of space and time. Moreover our runaway universe appears to be rather delicately balanced, in the sense that small changes in the laws of nature would result in a very different cosmos

[Jarvamundo]

90% 92% 95% constants.... cmon... lets do it... lets get there...

wheres the empiricism.

Re Hendry - Looks like he's built a career describing these hypothetical constants. He's part of the 650 million dollar, 30 year, seismic noise detection project.... i mean LIGO.

I prefer Bryan Gaenslers work on magnetism (http://sydney.edu.au/science/physics/~bmg/papers/stories/301Gaensler-3.pdf)
"It turns out that many previously unsolved problems in astronomy suddenly make sense once one includes the effects of interstellar magnetism." (galaxy rotation problem included)

These gravity-dominant boys have gotta look over the fence and come to the EM party... spirals forming everywhere.

[g__day]

I don't read more into yet then they have alot more data to study and this should improve models.

Until we have a model for daark energy - explaining what it is - is premature to scoff or contest its wrong; all we can say is show us a theoretical model that can be evaluated. In the mean time scientists look for other alternate models that try and explain the data we have today that can be assessed and evaluate observations with any new models laws - explicit or inferred.

We live in interesting times huh?

Matt

[Jarvamundo]

would be equally premature to contest it's right. I'm only pointing out it's a pretty big 75%+ hypothetical of new "invented" physics... 90%+ if you include the "invented" form matter.

Bryan's work just applies known physics to real empirical measurements of interstellar magnetic fields, detected and mapped by faraday rotation. "real stuff". not inferred... real lab physics.

he has not dismissed expansion or bbt.... just acknowledging and mapping real stuff thats out there, which standard ignores.

Just a bit of honest perspective here.

[sjastro]

Was Neptune "invented" to account for the orbital issues of Uranus?
Or was it a profound example of Newtonian theory at work?

Neptune was the "dark matter" of the mid nineteenth century.

http://en.wikipedia.org/wiki/Discovery_of_Neptune

Regards

Steven

[Jarvamundo]

Excellent SJ... Exactly. It's a hypothetical... or name for how far the mathematic descriptions are off as with the neptune example.... Lets apply some humility employing "new force" or "new physics". I agree mathematics should continue to describe how far off empirical physics is from observations, it's a very important process. Lets just be careful about saying new hypothetical physics actually exists, simply because it has to. I feel this perspective gets pushed to the side to grab a headline these days.

It's as likely history will repeat, and new physics is not required. Meanwhile mathematics has done an excellent job of describing the problem.

[avandonk]

No theory has any validity until it predicts a measurable unforseen consequence!

Bert

[Jarvamundo]

I agree again, was dark matter / energy predicted or is it an ever changing mathematical description of the problem? (ie it describes would be required by a gravity-only model to correct that original galaxy rotation graph). Tis why it's best describes as a hypothetical entity for now, to me thats just simply defining the problem? Something 'real' is certainly premature.

The predictions of a model containing 90%+ constants (new physics) should be carefully assessed and weighted, there's alot of room to move.

[sjastro]

Neither.

Dark matter and dark energy evolved from observation.
The theoretical aspects are derived from mainstream theory not invented.
This is why I used Neptune as an analogy for dark matter.
Scientists took an existing theory (Newtonian gravitational theory) and applied it as a perturbation to the orbit of Uranus.
In other words there was no need to alter the theory.

The same type of reasoning applies to explaining the rotational curves through the presence of dark matter.

Dark energy although not as clear cut has it's origins in quantum field theory. It attempts to explain the cosmological constant as a vacuum energy fluctuation.
The point is that neither dark matter or dark energy involves "new" physics. It's an increasing crossover of QFT into cosmology and celestial mechanics.

The fundamental problem with dark matter is that if it does exist it will impact on the Standard Model in particle physics.
If dark matter turns out to being ordinary matter observed at a different wavelength then no such problem exists.

Regards

Steven

[Nesti]

That's the question I asked Dr Hendry when he gave his talk on Dark Matter and Dark Energy. I asked him that shouldn't the sheer presence of Dark Matter call for the Standard Model to be revised, or, a at least a super-symmetric version. In the case of a super-symmetric version, the Gravitino looks like it couldn't be the origin of Dark Energy, so we're still stuck with at least one of them.

I think he was visiting UWA to promote gravity wave research.

[Jarvamundo]

heheh it's a good business mark.... LIGO's is in the process of securing more dollars, i'd imagine they'll also be pushing for the $4Billion lisa experiment. Re LIGO: a few hundred million, 30 years, for 5 funded science runs and all you detect are loggers (which you can't shut down so you have to do science at night), moon noises, people walking in the office. Best part is you have a non tune-able gravity antenna that you can never aim, plagued by seismic activity and the agreed best chance scenario is 1 event per year.


Re SJ: Thanks for your points, but i wish to share some perspective on recent updates...



My understanding is that Zwicky postulated that this could be a theoretical solution for the galaxy rotation evidence that was a big thorn in the standard.

Essentially how the show went down: "Wow check out the arms of the spirals, they are also rotating around at a faster speed, ie the spirals are not twisting up on themselves as our gravity model would expect."

Enter the postulation of "extra" matter that we cannot see or ever detect by it's definition, only infer, but it will help tug the arms around, by Zwicky. Yes when Zwicky first postulated the solution he was laughed at, it was later picked up when QFT became popular and it provided a possible mechanism. It's important to note QFT has a number of hypotheticals of which are employed in the Dark Matter hypothetical solution.

"Evolving from observation".... hmm i don't understand this? I totally agree the maths has done very well in describing the problem, but "evolving from observation"... By it's definition we cannot observe dark matter with the observing technology we currently have. Maybe you mean we "observed the rotation problem, when then observed some QFT, but then employed some of the highly theoretical components as a solution. To say Dark Matter evolved from "observations" is well just being a little short on the story with laymans.

Dark Matter is clearly hypothetical or now wiki calls it a "conjectured form" of matter.
http://en.wikipedia.org/wiki/Conjecture


(It's interesting that wiki recently (09-10) back pedalled from "hypothesis" to "conjectured form", it is now more clearly defined as a mathematical conjecture)



From wiki http://en.wikipedia.org/wiki/Dark_matter:


The point is, lets just keep in mind how many times we say "hypothetical" or "conjecture", before drowning in mathematical champagne.

Lets also forward some humility to layman, and provide detail what we mean by "observations".

It would seem reasonable to at-least have a chat about the hoards of magnetism we are now mapping in the universe, a clearly non-hypothetical well understood force that hey... might just bring back these 90%+ gravity-dominated constants. Hey... even celebrate it as the dark-matter solution... i dun care... whatever... the stuff is actually there, and being mapped in detail by radio astronomers, which was not possible or available to the founders of standard.

Not saying "stop the maths", it is very very very important. Just saying hey... lets share some ideas and real data.

[sjastro]

From a celestial mechanics perspective read "dark matter=unobserved matter".
While dark matter cannot be directly observed it's effects on stars can be detected as a deviation of the Keplerian orbits of the stars around the galactic centre.
Hence dark matter is this context has originated from celestial mechanics using Newtionian theory of gravity.



Dark matter is definitely not a conjecture in the mathematical sense, but a hypothesis that is testable. This is a direct consequence of it's derivation from an existing theory.
Once again I refer to the Neptune example.

Also note that dark matter detectors do exist with the possibility that dark matter has been detected.
http://en.wikipedia.org/wiki/Cryogenic_Dark_Matter_Search

The irony is that variable gravity theories which remove this "conjecture of dark matter" are themselves unfalsifiable.



This doesn't define new physics. It's defining dark matter through QFT.
On the subject of hypothetical entities, many particles such as quarks, and the Z and W bosons were hypothetical entities 40 years ago. Theory determined their properties which allowed experimental verification to occur.
Hypotheticals are simply not made up to keep existing theories afloat.

Regards

Steven

[Jarvamundo]

Thanks Steve,


I agree here... i don't see any difference in both our posts.?.. There is "a" difference detected in these orbits. Dark Matter is one hypothesis. Interstellar Magnetism is another, i'm sure there are plenty of others. My point is... lets just be honest and not say "it IS dark matter", lets say "dark matter is one hypothesis".

Apart from that, we are on the same page with regard to "observations of dark matter" is one being inferred from newtonian g theory of the orbits you have mentioned.

As far as the other comments on scientific process with QFT, it's a slight connection there I guess, to be balanced we should announce how many hypotheticals failed... but i think we see the perspective there.

QFT is defining one possible hypothesis for Dark Matter Solution, i agree hypotheticals are made up to test. Wiki distinctly changed to "conjectured form of matter" recently, from hypothesised.... (just an interesting observation there).

My point is today we seem to be stacking hypotheticals up on each other, and declaring them as "it is dark matter"... I read papers of many stacked up on each other... I sometimes wonder if these modelers ever open to door next to them and have a chat to other fields.

Thank you for the dark matter detectors reference. Pointing out the falsifiable nature of the theory important.

I have yet to see a stable gravity-only model of evolutional spiral formation, the EM lads have had them for 30+ years now, Gaensler from Syd Uni is now mapping the magnetism in fine detail, using faraday rotation, it would seem a verification worth noting to me.

Best,
Alex

[renormalised]

There's that much conjecture about what dark matter/energy is that for the most part the best thing they can say is they don't know what they're looking at or really understand it. Yes, there are some reasonable hypotheses being suggested and I think the next decade of results from the LHC will bear out whether supersymmetry might be a deciding factor, or not, but that's for experimentation to decide. It's one thing to hypothesise the existence of supersymmetric particles through theory but it's something entirely else to actually produce the results empirically. I'd say given the track record of particle physics, they may find them (or they may have to ramp up the LHC's beam intensity further to find them), but you never know until you actually do the experiments at the proper energies. I wouldn't entirely rule out some form of baryonic matter either but I'm not going to hazard a guess as to what it might be for certain. I have a feeling that this question isn't going to go away for quite some time, yet. Not until we can actually sample or detect with certainty what's there.

As far as other theories go, interstellar magnetism/electrical fields, interactions with higher dimensions, modifications of Newtonian gravity, etc etc etc, they'll have to live or die on their merits through further observation and testing. For all we know, it might be a combination of factors which produce the results that we see. Sometimes, Occam's Razor doesn't cut properly because it's blunt :)

[astroron]

Why do we still stick to the Baryonic measurements when we keep finding Galaxies that are Larger and further back in time.:shrug:
Would some one please explain how we deduce how much matter is in the Universe when we keep finding more and more galaxies and other Stuff.
We find that the Voids are not Voids after all, but filled with Millions of galaxies that don't show in most of the electromagnetic spectrum.:shrug:

[Nesti]

All this hub-hub about dark matter and dark energy...we can't see light, only detect its presence, yet everyone seems to think they know what that is (yet we don't). Same goes for every other particle...what makes the dark side so interesting.

Perhaps Obi Wan was right, the dark side is more seductive :lol:

[Nesti]

Because WMAP - built under contract of the lowest bidder - said so, now behave Ron! :D

[Jarvamundo]

EM has been powering: Sun spots, CME's, auroras (http://en.wikipedia.org/wiki/Kristian_Birkeland), solar currents between planets and moon (http://hubblesite.org/newscenter/archive/releases/2000/38)s + 2 Trillion Watts (http://csep10.phys.utk.edu/astr161/lect/jovian_moons/io.html), between sun and planets, between planets and planets, radio astronomers are now mapping it in detail of galaxies, both our own and others. ie.. it's everywhere we've sent a probe, and there's loads of it.

It's all experimentally verified, tested in the lab. Empirical as it gets.

Lets also keep in mind what is powering this precious LHC experiment... yep a giant electro-magnetic dumping massive currents into it.... we are building the biggest EM machine ever to try and have a chance at finding a higgs, so we can patch up a gravity-dominant model?... anyone else see the irony in this? where is that razor?

The current mainstream gravity-dominated-cosmological models flat out ignore EM, a well understood empirical science, and in doing so are required to create these mathematical conjectured (http://dictionary.reference.com/browse/conjecture) entities. A gravity dominated model cannot produce a spiral galaxy, EM's been doing it for 30+ years (http://en.wikipedia.org/wiki/File:Peratt-galaxy-formation-simulation.gif). Connect the dots?

I agree it'll end up being a "combination" of these theories that get through... it'll be a "hey look what we (re)discovered moment".... Mainstreams now extending the hand (http://www.iceinspace.com.au/forum/showthread.php?p=568750)...

[renormalised]

I'm not disputing the evidence and/or influence of EM in the cosmos. As a matter of fact it's an important part of understanding the processes which go on within stars, planets, galaxies etc etc. But like anything else, it still requires ongoing study, testing and such. No field of science can be considered static, and neither should those that work in them consider it as being as such.

We also have to look at stuff such as MHD, condensed matter physics and the like to fully appreciate what's happening out there.

[Jarvamundo]

I know you're not... consensus cosmo models currently ignore it.

Condensed matter theories also have difficulties and violations of empirical nuclear physics (http://en.wikipedia.org/wiki/Island_of_stability)... the current gravity-neutron-star (spinning neutronium) is a shining example... direct violation of all matter we know.

These are of course one of the conjectured spinoffs of ignoring EM in the stellar models, and relying on gravity to 'hold together' a postulated sustained fusion reaction, of man has yet to empirically verify.

[sjastro]

I fail to see the connection. Neutron stars are formed by the collapse of stellar cores composed of iron nuclei.
How is this related to the island of stabilty?

Regards

Steven

[Jarvamundo]

Neutron stars are 'hypothesised' to consist of a core of free neutrons... hypothesised 'neutronium' or these 'condensed matter' postulations.

The island of stability essentially describes the empirical nuclear physics of the relationship of protons to neutrons that are stable in atoms... 1 to 1 for light elements... kick it up to 1.5 to 1 for the heavy ones... you can see from the diagram it's a near 1:1 sorta line...

As the island describes... if there are too few neutrons the atoms will emit protons to stabilize... vicer versa...

With the neutron star we are talking about a nucleus, not of iron, but of free neutrons, or postulated condensed neutronium only, that according to the island is completely unstable and will immediately decay.

My point being... The hypothesis of a 'neutronium', 'quark matter', 'strange matter', 'neutron core' neutron star is stretching out far beyond empirical nuclear physics.

Best,

[bojan]

Are they really free?
The density of neutron star seems to be very close to nucleus density..

[sjastro]

Gravity is the reason why neutron stars are stable. A free neutron will decay (via the weak force) in about 15 minutes, as will a neutron only nucleus.

One of the principal reaction pathways for the formation of neutrons in a neutron star are electrons being squeezed into the iron nuclei due to the immense gravity and interacting with protons to form neutron only nuclei.
These nuclei in turn form neutron degenerate matter which is a major component of neutron stars.

In this state if a neutron decays into a proton and electron, gravity causes the proton and electron to form a neutron. In other words neutrons are in equlibrium with protons and electrons.

For every neutron that decays, a neutron is created hence neutron stars are stable.

Regards

Steven

[Jarvamundo]

Alot of hypotheticals there again SJ...

I'm familiar with the 'gravity' being hypothesized mechanism for the existance of this process. Zwicky coined it up not more than a year after the discovery of the neutron.

My comparisons were between empirical nuclear physics and hypothesis, in response to Marks comments on empirical verification required for competing models.

You are right with a neutron and the 15 minute decay.... lets take a look at the other proposed neutron matter

http://en.wikipedia.org/wiki/Neutronium


Only one of them really exists... (the first one)



Well has anyone actually dissected a neutron star? Has anyone ever been able to get 2 neutrons to stay together? Has anyone ever been able to produce a sustained fusion reaction?

We have yet to really get 2 neutrons to hangout together, let alone a spinning star full of em.

I'm just saying, we are invoking alot of stuff they we don't have empirical verification for, and we haven't even started to talk about how fast these massive objects are 'supposed' to spin....

mainstream sets the bar high for competing models to provide empirical evidence, just seems to me consensus can coin up as many terms as it wants without equal empericism. 'Strange matter' cmon...

[bojan]

Dissected star? no...
But, if we assume the rot momentum is preserved during collapse, a very simple calc will show that the spin of couple of hundred rotations per second for solar mass star actually could started as much more common couple of days for one rotation prior to collapse.
This way, you know how big the neutron star is and what is its mass - there are gravitationally bound systems with at least one neutron star (pulsar) as a component, so masses of components are known very precisely.

[Jarvamundo]

Yes i'm familiar of the gravity model. Just saying neutronium does not empirically exist, it's hypothesized to exist based on the insane speeds this things are said to "spin". This was spin rate NOT expected or predicted, Neutron Star was invented as the only thing that could stand those rotational speeds.
If you get the island of stability chart... then doink a neutron star on it... it's off the graph paper.

Whilst on speed of rotation... even neutronium flings apart when we hit this speed (24,000 RPM): http://prl.aps.org/abstract/PRL/v83/i19/p3776_1

so now we invent 'strange matter' as even the super dense hypothetical neutronium would fling apart...

Yes gravity is hypothesized to save the day.

Comments are on empirical perspective component of this proposed science. I do not question the maths invoked to infer the existence, as you have described.

[sjastro]

Alex,

Hypothesis and theory are based on observation/experiment. Hypothesis is not invented to support theory. My explanation of gravity in this context is a case in point.

It is based on two pieces of observation.
(1) Neutron stars do exist.
(2) Neutron stars last longer than 15 minutes.

Now if gravity plays no role (or doesn't exist) for neutron stars (which can't exist long term without gravity anyway) then we have a very serious problem in explaining the whole concept of nucleur fusion in stellar cores. The KE of nuclei due to the stellar temperature of the core is not enough to sustain long term nucleur fusion. Fusion also occurs through the conversion of gravitational potential energy into KE.




Free neutrons only exist in neutron stars because the matter is degenerate. If neutron matter is not degenerate there is nothing preventing the neutron star from collapsing into a black hole.



Once again it's not the case of inventing terms or hypothesis to support theory. Strange matter is a theoretical outcome of Quantum Chromodynamics.

Antimatter strange nuclei have been recently discovered at the RHIC.
http://physicsworld.com/cws/article/news/41917

Regards

Steven

[Jarvamundo]

Ok... it might be palatably said as... it seems todays cosmological models are quick to pickup the nearest convenient discovery and mould it to fit the difficulties in observations... Well prior to any empirical lab observational confirmations that the process can take place.

* sustained nuclear fusion (aint happened)
* magnetic reconnection (aint happened)
* 24,000 rpm super heavy beyond anything dreamt of in the lab_ matter star (?)

....
1933 Chadwick discovers the neutron
1934 Zwicky uses it to fit the problem of these fast spinning stars

The type of star existed before the 'Neutron' Star did
The type of star lasts longer than 15 minutes

Quark and strange follow suit... they now have their own hypothetical stars...

I'm just sayin... never seen a cup of neutrons under pressure (of any force) staying together...

I think we know where this is going.... just my empirical conscience having a rant...

Best