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

[g__day (Matthew)]

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/2010/0...niverse-found/

The universe as we know it 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

[gary]

Thanks for the link.

[wasyoungonce (Brendan)]

Originally Posted by g__day

So is this the dust bin for alot of dark energy scenarios?

Well this still would not account for the steady state rotational orbital velocity of stars within a galaxy. This can only really be accounted for by the cosmology standard model.

[Jarvamundo (Alex)]

Originally Posted by wasyoungonce

Well this still would not account for the steady state rotational orbital velocity of stars within a galaxy. This can only really be accounted for by the cosmology standard model.

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 (Brendan)]

Originally Posted by 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.

I believe the addition of dark energy with the dark matter model is the current working standard model.

[Jarvamundo (Alex)]

Originally Posted by wasyoungonce

I believe the addition of dark energy with the dark matter model is the current working standard model.

containing 90%+ inferred hypotheticals
http://en.wikipedia.org/wiki/Dark_Ma...isambiguation)

Dark matter is a hypothetical type of matter that is undetectable by its emitted radiation, but whose presence can be inferred from gravitational effects

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 (Brendan)]

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 (Mark)]

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

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 (Alex)]

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
"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 (Matthew)]

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 (Alex)]

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 (Alex)]

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 (Alex)]

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]

Originally Posted by 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.

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 (Mark)]

Originally Posted by sjastro

The fundamental problem with dark matter is that if it does exist it will impact on the Standard Model in particle physics.

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 (Alex)]

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

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...

Dark matter and dark energy evolved from observation.

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

A conjecture is a proposition that is unproven but appears correct and has not been disproven. Karl Popper pioneered the use of the term "conjecture" in scientific philosophy. Conjecture is contrasted by hypothesis (hence theory, axiom, principle), which is a testable statement based on accepted grounds. In mathematics, a conjecture is an unproven proposition or theorem that appears correct.

(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)

The point is that neither dark matter or dark energy involves "new" physics.

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

The vast majority of the dark matter in the universe is believed to be nonbaryonic, which means that it contains no atoms and does not interact with ordinary matter via electromagnetic forces. The nonbaryonic dark matter includes neutrinos, and possibly hypothetical entities such as axions, or supersymmetric particles.

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]

"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.

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 clearly hypothetical or now wiki calls it a "conjectured form" of matter.

A conjecture is a proposition that is unproven but appears correct and has not been disproven. Karl Popper pioneered the use of the term "conjecture" in scientific philosophy. Conjecture is contrasted by hypothesis (hence theory, axiom, principle), which is a testable statement based on accepted grounds. In mathematics, a conjecture is an unproven proposition or theorem that appears correct.
[

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/Cryogen..._Matter_Search

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

The vast majority of the dark matter in the universe is believed to be nonbaryonic, which means that it contains no atoms and does not interact with ordinary matter via electromagnetic forces. The nonbaryonic dark matter includes neutrinos, and possibly hypothetical entities such as axions, or supersymmetric particles.

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 (Alex)]

Thanks Steve,

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.

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