Hubble Survey Finds Half of the Missing Matter

esocid sends along the news that scientists believe they have found about half the missing matter in the universe. The matter we can see is only about 1/8 of the total baryonic matter believed to exist (and only 1/200 the mass-energy of the visible universe). This missing matter is not to be confused with "dark matter," which is thought to be non-baryonic. The missing stuff has been found in the intergalactic medium that extends essentially throughout all of space, from just outside our galaxy to the most distant regions of space. "'We think we are seeing the strands of a web-like structure that forms the backbone of the universe,' Mike Shull of the University of Colorado explained. 'What we are confirming in detail is that intergalactic space, which intuitively might seem to be empty, is in fact the reservoir for most of the normal, baryonic matter in the universe.'"

Comments

Ether

[teknopurge]

Haven't we known this for some time?

Re:Ether

[Anonymous Coward]

I knew someone was going to make an ether comment. The luminiferous ether was the hypothecial medium that electromagnetic waves (including light) traveled through. It was hypothesized because, at the time, there were no known waves that traveled without a medium. However, the ether was disproven, and it was shown that EM waves travel without a medium. What's mentioned in the article is not ether.

Re:Ether

[CowboyNealOption]

The ods would do better if they remembered to take their eds every orning.

Re:Ether

[Anonymous Coward]

Yup, Disproven.

Because Einstein got everything perfect (cosmological constant)
And light (which may or may not have mass) is bent by gravity (bending space time)

Wouldn't it make more sense to go with an aether theory?

You say light travels at the same speed regardless of direction or relative motion? I say bunk requiring some very sophisticated manipulations of time and space (Lorentz contractions) What's wrong with the 'entrained aether' theory? What, you never heard of frame-dragging?

Gravitational lensing? How about gravity increasing the optical density of the aether?

*puts away tin foil hat*

Re:Ether

[nomorecwrd]

Off course!

Isn't this the matter that strikes the shields at Warp speeds?

Re:Ether

[hardburn]

Not disproven, really, but fell away due to Occam's Razor. The difference between ether and this "web-like structure" is that ether was never directly observed.

Re:Ether

[scorp1us]

How can you disprove EM travels without a medium, if our world is made of matter in that medium? You can of course remove the matter (create a vacuum), but that doesn't remove the medium.

I'm not trying to be antagonistic. I'm legitimately curious.

Re:Ether

[Uncle Focker]

Because Einstein got everything perfect (cosmological constant) And light (which may or may not have mass) is bent by gravity (bending space time) Wouldn't it make more sense to go with an aether theory? Not when it's wrong. I'm sorry if reality is too complicated for you, but that's your problem not ours.

You say light travels at the same speed regardless of direction or relative motion? I say bunk requiring some very sophisticated manipulations of time and space (Lorentz contractions) What's wrong with the 'entrained aether' theory? What, you never heard of frame-dragging? No, light travels at a constant speed in a vacuum. It's speed can be different based on a whole variety of factors.

Gravitational lensing? How about gravity increasing the optical density of the aether? Have any evidence to back this up?

Re:Ether

[naasking]

Wouldn't it make more sense to go with an aether theory? [...] How about gravity increasing the optical density of the aether?

The problem with ether theories is mainly the Michelson-Morley experiment. Are there ether theories which avoid the MM pitfall? Sort of. The Polarizable Vacuum (PV) is a very interesting theory along the lines of what the the above poster suggested. Instead of matter bending some mysterious "ether", as in ether theories, or bending space-time, as in relativity, matter instead affects the electric and magnetic permeability of space, which causes light to behave as if it were passing through a medium with a higher dialectric constant. From that simple assumption, we can almost rederive full general relativity (GR) wherein electromagnetic equations produce gravitational effects. Gravity is electromagnetism! PV has since been disproven, but it's still a stunningly simple way to think about gravitation in terms of electromagnetism.

Re:Ether

[sir fer]

disclaimer: I am a physics graduate. EM waves consist of an oscillating electric field (along with its magnetic counterpart)...what was that electric field doing before it started oscillating? It was probably a static field. Think about this, if I have a magnet and I wiggle it around, the disturbance in the field of the magnet travels outward from the source at the speed of light, but the field was there but merely static initially. Same deal with gravity waves. So whether the local field is static or oscillating, it was always previously existent regardless of its state. While I don't believe in the luminiferous aether either I also don't see how a field disturbance (electric, magnetic or gravitational) can travel through something that isn't there. I hope people can see what I'm talking about because while relativity and the aether don't make sense on their own, there are aspects of both theories that accurately describe reality and as is often the case in modeling reality it is not often a case of either / or, eg wave-particle duality in describing the sub-atomic world.

Re:Ether

[TropicalCoder]

I've got a question for a physics graduate or anybody who can answer it. After reading for the thousandth time about all the ionized gasses in space, I suddenly began to wonder how many electrons were created in the Big Bang? Like - are there enough electrons for every atomic nucleus to fill it's shells - if they weren't ionized? Now, that seems improbable, because an enormous amount of matter was created after the Big Bang - created in stars and super novae. Then this matter that was created - were electrons created at the same time in proportion? ...and in the balance of things - how many electrons are there in the Universe and how many protons are there? ...and how much do all these electrons weigh? ...and all these electrons that were striped from interstellar matter to leave behind ionized gasses - where did they go? Well I would guess they are zinging along some magnetic field lines someplace, quite happy to be alive, but is there some place where they collect in huge clouds? I don't suppose that is too likely, because electrons are antisocial among themselves and stay as far apart as possible, but on the other hand, protons are like that too among their own kind, yet somehow manage to form clouds. So then you think about these huge clouds of hydrogen and helium nuclei, all longing for the company of electrons, but there are none to be found in the region - such huge imbalances must exist. Makes you wonder when matter finally conglomerates into planets and such that somehow there is suddenly just the right number of electrons available so that every single atom can fill is orbital shells. How does this come about?

Re:Ether

[lgw]

Well, if you assume that the Earth moves through such a medium as it orbits the Sun, you can look for that, as you can tell there's a medium when you move relative to it - which was the Michelson-Morley experiment.

Re:Ether

[hardburn]

The universe likely has neutral charge. Also see a more detailed discussion on the subject.

Re:Ether

[hardburn]

Michelson-Morley was an important part of it, but it was Einstein that finally killed it off by proving that waves and particles aren't as seperate as they appear to be, and thus ether is unnecessary. A few stodgy professors hung on for a while, but they eventually retired/died off without convincing very many of their students.

Re:Ether

[TropicalCoder]

Thanks! I found the answer, and read some very interesting discussion in the links you provided. Interesting that though I have been reading about physics and astronomy for many years, I have never run into this kind of discussion before...

"The electromagnetic force is so strong that if the universe had even a slight net charge, electric and magnetic fields should dominate the structure of our universe. But it doesn't -- gravity does. And gravity, believe it or not, is a very weak force. There are other effects that electric and magnetic fields would have on light, and we simply do not see these effects."

"If a gas in ionized it simply means that some electrons have separated from the constituent atoms (or molecules) that make up the gas leaving positively charged atoms/molecules and negatively charged electron. However they are still mixed together in the same gas, the 'separation' that you assume does not exist. The positive and negative charges still mingle in the same space. Even if you took a very small volume (the size of a grain of sand) of an ionized gas the overall charge is still neutral."

Re: Ether

[EPAstor]

It's not quite like that... Quantum states' collapse is barely real in the sense that we know it. In particular, it doesn't carry information - so the experiments we already have, which indicate that what we call collapse is a non-local phenomenon (carries faster than the speed of light, possibly instantly), don't contradict special relativity.

Yes, you read correctly - to all our best measurements, collapse appears instantaneous, not like a propagating change in a wave.

Re:Ether

[BZ]

Wave function collapse is a much more controversial thing than the existence or non-existence of the ether. Basically, it's the only non-unitary, non-differentiable, discontinuous part of quantum mechanics. Oh, and it violates special relativity, though that might count for less given the topic of discussion here. There are various suggestions (such as many-worlds theories) that might avoid the need for this artificial wavefunction collapse altogether.

Back to the topic at hand, the interesting thing with special relativity is that while it was created based on the results of the Michelson-Morley experiment, it doesn't actually "explain" that experiment. It just assumes the results of that experiment, somewhat generalized (light travels at the same rate in all inertial reference frames), and then makes a wide variety of predictions that differ wildly from Newtonian mechanics, have been verified experimentally, and have nothing to do with electromagnetism (and thus are not likely to have to do with the ether).

The two obvious examples:

  * Predictions about things like energies required to accelerate a given
      mass to a given speed. If the speed is a significant fraction of
      3*10^8 m/s, the predictions are very different from the Newtonian
      ones, and the special-relativistic predictions match experiment.
  * Predictions about time-dilation. There is a very interesting
      experiment one can do using the Mossbauer effect (in iron, say). The
      width of the absorption line for gamma rays in the iron nucleus is
      very small, so that one can measure doppler-shifts on the order of
      10^{-13} of the gamma ray frequency. That turns out to be sensitive
      enough that if you have two samples of iron at somewhat different
      temperatures easily producible in the lab (somewhat below 0 C and
      close to 100 C, say) the gamma rays absorbed by one sample are NOT
      absorbed by the other one. By moving one of the samples to introduce
      a doppler shift, one can find the exact amount of the frequency shift.
      If you then try to account for this frequency shift, it very closely
      matches the prediction one gets by applying special-relativistic
      time-dilation due to their thermal motion to the iron atoms. I
      haven't seen a decent alternate explanation for the results of this
      experiment.

I'm not sure I've seen a decent explanation of either of those in terms of things like frame dragging...

Re:Ether

[khayman80]

Not exactly... The MM experiment predicted a phase shift when the optics table was rotated. It wasn't time-dependent. The phase shifts expected by LIGO/LISA are sporadic events that should only be sensitive to huge events such as black hole creation or neutron star mergers. They won't vary with the orientation of the plane of the interferometer, and they won't be constant in time either.

Re:Ether

[locofungus]

Why does wavefunction collapse violate SR? SR prohibits information traveling faster than light. The no-communication theorem http://en.wikipedia.org/wiki/No-communication_theorem (I'd always called this the no-signaling theorem) leads to the no-cloning theorem http://en.wikipedia.org/wiki/No_cloning_theorem so if you like, SR "explains" the no-cloning theorem. (The no-cloning theorem still allows a cloning fidelity of 5/6. Last I saw, fidelities of 0.81 had been achieved)

Back to the topic at hand, the interesting thing with special relativity is that while it was created based on the results of the Michelson-Morley experiment, it doesn't actually "explain" that experiment.

Maxwell's equations (see sig) predict that light will propagate with a speed c independent of frame. Einstein had a choice, Newton was wrong or Maxwell was wrong. A non-null result from the MM experiment would invalidate Maxwell's equations.

So, if you like, Maxwell's equations "explain" the null MM result.

Tim.

Re:Ether

[orangesquid]

I'm taking a grad-level course in optical properties of condensed matter, and one of the things we study is how EM propagation is slowed by atomic dipole formation in polarization from photonic fields. It would be interesting if it were the case that the vacuum could be demonstrated to have, at the quantum level, some degree of spontaneous polarization in a field, and since there's always a field (even if perhaps self-induced from uncertainty foam), you could somehow make an analogy to the concept of the aether (even though it would not have the properties of the aether). However, as far as I've studied, that's not the case, because you can't ever rid yourself of QHO's unless you have a universe with no net matter/energy (which we don't have, even if you are looking at a gauge symmetry), no uncertainty principle (but matter waves obviously exist, because you can even diffract molecules), or you can demonstrate that QM is based a flawed assumption, viz. that matter waves don't extend to infinity (but experiments with entanglement have demonstrated that assumption to be accurate to a very high degree). Of course, we don't have a solid definition of what exactly constitutes an observer, but as far as formalism is concerned, most of our results don't need one.

And, yep, I *am* talking out my ass ;). No, actually, if it weren't early in the morning, and I weren't busy working on other things, I would go back and make the above paragraph (a) cite references, (b) use accurate and proper terminology rather than vague concepts, and (c) convey my thoughts with some rigor instead of a bunch of conjecturous statements.

Re:Ether

[Muad'Dave]

...it's spelled æther.

Only if you're Ænglish.

Ok, fess up

[pauljuno]

Come on, which one of you took it?

Re:Ok, fess up

[somersault]

It was like that when I got here.

Dark Matter???

[omnichad]

Always wondered why a simple explanation like dust never took hold, and everyone started talking about invisible matter to explain what should be there.

Re:Dark Matter???

[CheshireCatCO]

This isn't dark matter. Dark matter shows evidence (based on its measured distribution) which is not consistent with ordinary baryonic matter.

Re:Dark Matter???

[Btarlinian]

Always wondered why a simple explanation like dust never took hold, and everyone started talking about invisible matter to explain what should be there.

We know that there is some sort of matter missing due to weird graviational interactions. We also know that according our measurements of the cosmic microwave background, this matter doesn't exist, i.e., this matter doesn't interact with electromagnetic fields. That's why it's not normal baryonic matter.

Therefore, we say that there must be dark matter. Plain old dust would have showed up in our readings of the CMB.

Re:Dark Matter???

[pilgrim23]

old mother Hubble,
looked through the rubble,
to find all the matter was gone.
Till 'tween galaxies bright,
to their delight,
they found the brayons

Re:Dark Matter???

[JebusIsLord]

No, it says we've been missing ionized hydrogen and helium within a certain temperature range. How about reading the article before posting next time?

Re:Dark Matter???

[Tenebrousedge]

Well, dust is not dark matter. There's other matter besides baryonic matter. There's a great picture on wikipedia that 'shows' dark matter. The debate on dark matter is how much it exists and its exact nature, not whether it exists.

Re:Dark Matter???

[omnichad]

Poor neutron...

Re:Dark Matter???

[QuantumFlux]

"brayons"?

Are those like crayons for donkeys?

Re:Dark Matter???

[Tenebrousedge]

Fine, find some sort of matter interacts gravitationally with the observable universe but not electromagnetically, and call it whatever you want when you do. We'll be over here calling it non-baryonic matter, or dark matter.

Re:Dark Matter???

[CheshireCatCO]

Hydrogen and helium are not dust by any definition of "dust" I've ever known an astronomer to use. Dust is, by definition, solid matter which is microscopic, but much larger than atoms. To broaden the term to include plasmas and gases would pretty much make it so broad as to be useless.

So no, not dust.

Re:Dark Matter???

[Chris Burke]

More things that were supposed to be dark matter that turned out to be pretty ordinary matter.

No, that's not true. We already knew there was "ordinary" matter we hadn't found, we knew it wasn't "dark" matter, we just didn't know where it was. Now we found a bunch of it.

Re:Dark Matter???

[Btarlinian]

Ok, sure I did. But I think you missed the point. I wasn't saying anything was dark matter. I'm saying we found more real matter. Those generous question marks were my pokes against people who want dark matter to explain everything away when perfectly normal matter will suffice.

Except there aren't people like that. We knew this normal matter existed, we just didn't know where it was.

Every time we talk about something new being found in the universe, someone likes to say, "Oh look at those stupid astronomers, making up stuff no one can prove. There never was any dark matter." I know that's not what you specifically said, but by bringing it into the conversation and conflating this observation with theories of dark matter, you essentially did the same thing. Your basically attempted to make other people look stupid by making an ill-informed, seemingly insightful comment. I'm rather disappointed to see that it that the mods fell for it.

Re:Dark Matter???

[lgw]

although how the universe's biggest ever black hole could have expanded past its own event horizon is beyond me. But then I'm only a physics grad. Has it? The "diameter" of the event horizon grows linearly with mass, but an object of fixed density grows with the third root of mass, so as mass increases you'd expect the Schwarzschild diameter to grow faster than the size of the object.

The Schwarzschild "diameter" (circumference over pi) is 4 G M / c^2, or 2.969 * 10^27 m/kg.

The mass of the (observable) universe is about 10^53 kg.

The Schwarzschild diameter of the (observable) universe is therefore about 3*10^10 light years, within an order of magnitude of the probable diameter of the observable universe.

The universe as a whole is probably many orders of magnitude bigger than the observable universe, so it seems quite likely that we're all still inside that event horizon.

Re:Dark Matter???

[shma]

Cosmologists use the term 'dust' to refer collectively to non-relativistic matter in the early universe.

In the most basic big bang model, there are only two kinds of matter which we consider: 'dust' and 'radiation'. All non-relativistic matter is treated as a pressureless fluid which we call 'dust', while all relativistic matter is lumped together as 'radiation' and treated as an ultralativistic fluid: one whose kinetic energy is so great that its rest energy is only a small correction to its total energy, and can be neglected (so we can treat them as if they were massless photons).

These definitions aren't used outside of cosmology, so generally you won't hear about them in this context.

This proves the existance of God!

[Anonymous Coward]

We think we are seeing the strands of a web-like structure that forms the backbone of the universe

It is a noodle like structure. FSM 1 ID 0

Wow

[digitrev]

That's actually pretty cool. I mean, the fact that matter was missing was a bit of a problem. The fact that it's in between galaxies even explains why it was missing. When it's that spread out, it's damn near impossible to see the gravitational effects of it.

Re:Wow

[Tenebrousedge]

Great, except the problem is that we're trying to figure out what we can measure by its gravitational effects but doesn't interact in any other way with normal matter. This is the solution to a different problem.

Re:Wow

[ChrisA90278]

What was found here was missing __baryonic matter__ the bigger question is still unanswered. Bryonic matter is the normal stuff we are made of but most of the "stuff" in the universe is non-baryonic and still "missing".

Re:Wow

[GanjaManja]

(actually, they mention that regular matter is not detected via gravitational effects, they simply observed the absorption spectrum. However, when the gasses are highgly ionized, there are no electrons spinning around waiting to absorb the light, and thus the ionized Hydrogen does not yield an easily detectable absorption. (see 2nd article) "dark matter", non-regular matter, is detected via the gravitational lensing effects. )

Transcript of Hubble Survey Team Findings

[RealErmine]

"Oh, there it is."

I'm still waiting for them to find all the missing socks.

Missing socks...

[msauve]

find the missing socks, and you've found God. They're all in Heaven, you get them back when you die. All the Bic lighters, too.

The universe has a backbone?

[davidwr]

Damn and all this time I thought it was an invertebrate.

Re:Obligitory

[xaxa]

No, but it was in the last place they looked.

Douglas Adams's theory of missing matter

[speculatrix]

Douglas Adams had a theory about missing matter...

For a long period of time there was much speculation and controversy about where the so-called "missing matter" of the Universe had got to. All over the Galaxy the science departments of all the major universities were acquiring more and more elaborate equipment to probe and search the hearts of distant galaxies, and then the very centre and the very edges of the whole Universe, but when eventually it was tracked down it turned out in fact to be all the stuff which the equipment had been packed in.

Universe Half Empty/Half Full?

[ireallylovelinux]

Is your universe half empty or half full?

Gene Ray was right after all!

[Fortran IV]

No—it can't be true! The Hubble has managed to photograph the Time Cube! The joke really is on us...

And the irony is...

[tjstork]

Every time we talk about something new being found in the universe, someone likes to say, "Oh look at those stupid astronomers, making up stuff no one can prove

That statement is essentially true. The best you can ever know about the universe is by inference. Standard candles are an approximation and you aren't really able to prove anything by duplication as much as you are trying to say this is a pretty good story based on a computer model kicking out a similar result. I mean, it all sounds pretty good on paper, but I could always make a computer model of the "real killer" stabbing Nicole and Ron, and not OJ.

Re:Had it been a snake...

[Chris Burke]

Um, why wasn't the entire EM spectrum scanned across the heavens instead of "discrete" well-known segments like radio, x-ray, visible, IR, UV, etc.? Is it a money and time issue? Otherwise it seems that this should have been found decades ago.

Because different wavelengths require different technologies to detect. Like to detect visible wavelengths you use big mirrors and/or lenses, while to detect radio waves you use antennas, and so forth. It's not as simple as "scanning" the entire spectrum.