Hubble Survey Finds Half of the Missing Matter 189
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.'"
Ether (Score:4, Insightful)
Re:Ether (Score:5, Informative)
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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
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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 electro
Re:Ether (Score:4, Informative)
The universe likely has neutral charge [ucolick.org]. Also see a more detailed discussion [physicsforums.com] on the subject.
Re:Ether (Score:5, Informative)
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."
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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.
That wave is not static, it's vibrational displacement is assumed inert/static because we have no way of approximating such a minute difference in change, for now.
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I realize I'm saying that photons are made of EM fields which are made of photons, but well, they sorta are.
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Bear in mind that "the field is oscillating" isn't really a clear description. This implies that the field is the medium, but it's not. Consider waves in a medium -- say, water. I
Evidence... (Score:2, Insightful)
Re:Ether (Score:5, Informative)
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 [wikipedia.org] (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.
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Not that I'm an outspoken advocate of aether theory or anything, I've just been bugged by that little thought since high school, and this seemed like a
Re: Ether (Score:4, Informative)
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.
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Back to the topic at hand, the interesting thing with
Re:Ether (Score:5, Interesting)
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.
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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.
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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.
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Re:Ether (Score:4, Informative)
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I'm not trying to be antagonistic. I'm legitimately curious.
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Except the one for which they were trying to find a medium. :-)
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Isn't this the matter that strikes the shields at Warp speeds?
Re:Ether (Score:5, Funny)
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Only if you're Ænglish.
Ok, fess up (Score:5, Funny)
Re:Ok, fess up (Score:5, Funny)
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With Jesus.
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Dark Matter??? (Score:3, Insightful)
Re:Dark Matter??? (Score:5, Informative)
Re:Dark Matter??? (Score:5, Funny)
looked through the rubble,
to find all the matter was gone.
Till 'tween galaxies bright,
to their delight,
they found the brayons
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Are those like crayons for donkeys?
Re:Dark Matter??? (Score:5, Informative)
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.
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Re:Dark Matter??? (Score:4, Informative)
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Maybe a better lightbulb? (Score:2)
Wouldn't a big blob of noble gases in the galaxies and then some sort of interstellar / undiscovered physics to mute the spectra do the trick?
I'm not an astronomer, but I thought the deal with dark matter is that it was necessary to explain the measured rotational speed of the galaxies -
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I read it... very interesting. It seems to me though, that "covered all the bases" really means "researched as much as we think we can with the tools that we have." It's like, you can't just go out there and measure stuff, you know. A lot of it is weighing subtle things together and making a case, until someone does something really amazing and discovers that background noise on a satellite antenna is actually radiation from the
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I read it... very interesting
Thank you!
The universe is a pretty cool place, really. Although in the case of the CMBR, it was theorized to exist before it was discovered experimentally.
what if space time isn't the flat sheet distorted like is thought
Well, actually, we've been able to measure that. Here's a summary [nasa.gov], but we're pretty sure that the universe is flat (parallel lines will never converge), to within a 2% margin of error. Neat work, that.
I have pretty much the same sense of wonder and awe when faced with the incredible complexity of the universe. It's such an incredible, marvellous thing
Re:Dark Matter??? (Score:5, Informative)
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.
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To which the answer is: NO, this is not the dark matter. This does not explain the dark matter. This is unrelated to dark matter.
Which is perfectly clear if you RTFA before posting. Or even payed close attention when reading the summary. I realize this are a bit much to ask. But when you post in ignorance, and someone says, "No, RTFA"
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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 basi
And the irony is... (Score:3, Insightful)
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
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Uh, physics is rooted in proof! (Score:2)
It goes like this, when an astronomer tells me something about the universe, or a biologist about the earth's past, they usually put together a chain of evidence in much the same way a detective tries to fit a puzzle together. It's interesting, for sure, but, when a physicist or a chemist tells me something, most of the time it is because THEY BUILT SOMETHING USEFUL. From physics and chemistry come a wide variety of materials and devices,
And in fact... (Score:2)
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Nobody has ever thought dark matter explained anything at all that this discovery explains instead. "Perfectly normal" matter does not explain anything that dark matter explains, assuming by "perfectly normal" you mean "baryonic". That is, in essence, the only thing we actually know about dark matter at all: There are things about the universe that cannot be explained by "perfectly normal" matter. If perfectly normal matter sufficed to explain these things, we wouldn't think there was d
Re:Dark Matter??? (Score:4, Insightful)
So no, not dust.
Re:Dark Matter??? (Score:4, Informative)
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.
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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 magnitud
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This proves the existance of God! (Score:5, Funny)
It is a noodle like structure. FSM 1 ID 0
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It is a noodle like structure. FSM 1 ID 0
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Do the noodles transmit data FTL? Maybe they're tachyon fibers.
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[all around the room, anxious faces lean forward in gleeful awe to hear the blessed man speak]
Wow (Score:5, Insightful)
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Transcript of Hubble Survey Team Findings (Score:5, Funny)
"Oh, there it is."
I'm still waiting for them to find all the missing socks.
Missing socks... (Score:3, Funny)
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I bet it's those damn "??? Profit" gnomes again.
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The universe has a backbone? (Score:3, Funny)
Oxygen and Hydrogen? (Score:2)
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If you put them together in a balloon nothing happens until you put a match to it, and it's probably a lot colder out in this part of space than my school's science lab was.
Better explanation (Score:2)
(Sorry for being wrong everyone. That's what happens when you stop studying chemistry at 18 and then forget stuff...)
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Wrong. gazeous oxygen will not react spontaneously, but high energy radiation will very rapidly ionize it anyway. On the other hand, ionized oxygen is so reactive it will oxydize the first non-oxydizer atom or molecule it touches, including hydrogen.
In the universe, the only gazeous oxygen we have found yet was created by plants. Without life, it only exists as water, CO2 and various oxydes.
Douglas Adams's theory of missing matter (Score:5, Funny)
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? (Score:2, Funny)
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Gene Ray was right after all! (Score:4, Funny)
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like mama always said (Score:2)
What About The Other Half.....? (Score:2)
Next job (Score:2)
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Hopefully by that time finding fuel will be less of a problem than it is now.
Re:Had it been a snake... (Score:4, Informative)
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.
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