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

[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

[hardburn]

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

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

[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.

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.

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

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.

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.

Transcript of Hubble Survey Team Findings

[RealErmine]

"Oh, there it is."

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

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

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.

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.