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Intergalactic Missing Mass Missing Again
Ponca City, We Love You writes "Researchers at the University Of Alabama In Huntsville have discovered that some x-rays thought to come from intergalactic clouds of 'warm' gas are instead probably caused by lightweight electrons — leaving the mass of the universe as much as ten to 20 percent lighter (in terms of its ordinary matter) than previously calculated. In 2002 the same team reported finding large amounts of extra 'soft' (relatively low-energy) x-rays coming from the vast spaces in the middle of galaxy clusters. Their cumulative mass was thought to account for as much as ten percent of the mass and gravity needed to hold together galaxies, galaxy clusters, and perhaps the universe itself. When the team looked at data from a galaxy cluster in the southern sky, however, they found that energy from those additional soft x-rays doesn't look like it should. 'The best, most logical explanation seems to be that a large fraction of the energy comes from electrons smashing into photons instead of from warm atoms and ions, which would have recognizable spectral emission lines,' said Dr. Max Bonamente. The work was published Oct. 20 in the Astrophysical Journal."
As light fans out, it does so at the rate of 1/r^2. Double the distance, and you've quadrupled the surface area of the light beam. You've also reduced the luminosity at any point in the beam's surface by a quarter.
But why do we just assume that gravity needs to fall off at the same rate as light?
a warm gas. (and lightweight electrons.)
cat sig >
is the obesity problem over then?
The other, slightly less, logical explanation is that the difference in mass can simply be explained by the number of missing ballpoint pens in the universe.
The best, most logical explanation seems to be that a large fraction of the current theories put out are similar to the remaining fractions in that they are all delivered out the little brown holes of out-of-control modern astro-theoreticians.
Please. It really isn't hard to show that the dependency on r can only take on a few values and still yield a universe that comes at all close to what we observe. For example, the only halfway-plausible power of r that allows closed orbits (such as planets around stars) in classical mechanics is exactly 2. All other values either don't allow closed orbits in general, or are trivially shown by experiment to be absurdly wrong. Now, we have observed that orbits aren't exactly closed (the most famous example being the precession of the perihelion of Mercury), but these were explained astoundingly well by relativity.
Astrophysics is way beyond getting the growth rate of a fundamental force wrong.
Do you really expect language like that to cause somebody to re-evaluate some of the most well-verified physical laws ever postulated?
"Einstein fanatics"?! "demigod"?! You sound like a crackpot UFO conspiracy theorist. If you think there are flaws with the current models, the only acceptable way to address those concerns is with science. Not ad-hominem attacks against people who are demonstrably smarter and more polite than you.
I can understand the universe being lighter, but its mass being lighter?
Now, back to my new computer that has a faster speed yet runs at a colder temperature. I'm going to move its location, which will require a longer length of Ethernet cable. Hopefully this farther distance from the router won't be a problem.
Based on nothing more than pure speculation, I believe the missing mass of the Universe is tucked away in all those little tiny extra dimensions at the planck scale of things.
Of course I'm wrong but hey - this is Slashdot.
Shh.
US Consumers Clueless about Missing Intergalactic Mass
...
"A study on consumer perceptions about missing intergalactic mass, undertaken by the Asimov Institute at the University of Phoenix Online and the Speilberg Space Policy Center, found that the average American consumer is largely unaware that some x-rays thought to come from intergalactic clouds of 'warm' gas are instead probably caused by lightweight electrons. Those surveyed showed little knowledge on the extent to which the mass of the universe was previously calculated. More than half of those surveyed -- about 55 percent -- falsely assumed that large amounts of extra 'soft' galaxy clusters were actually a light chocolatey candy.
Is the galaxy on the same diet as Oprah?
Have gnu, will travel.
He might be a crackpot, but the idea isn't. Google on MOND.
What's easier to believe - that there's a ton of missing mass out there as "Dark Matter" - something that we have no direct evidence for - or that gravity works differently on large scales than a smoothe 1/r^2 at all distances - and works exactly in the way that we observe? Remember that every time that we've had a strong classical theory replaced by something else, it's been at the extremes of our observation - the very fast for special relativity (which reduces to newtonian motion at lower speeds) and the very small for quantum mechanics. We know we're not getting something right on the large scale, and we know that our picture of gravity is incomplete, as we don't have a good quantum gravitational model.
I don't know, honestly - but it's clear that there's something we don't understand and I think that our human-scale intuition is not well suited for figuring out what explanation is more likely, just as QM and SR aren't very intuitive. Right now, we've got competing models but neither is very satisfactory without more data.
"It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny
The Einstein fanatics and the Big Bang proponents refuse to consider it as a possibility (a lot of careers depend on Big Bang and Esintein being right). Einstein is a demigod in some circles and his wisdom must not be questioned. As a result little funding is allocated for research in this area. That's too bad. We are probably missing some very exciting physics in the process.
Boy, this is spoken like someone who is completely disconnected from the academic process. There is no bigger fantasy a 20-something working on a phd physicist than to write THE paper that shows Einstein failed to account for some cosmological phenomon, that gravity is clearly explained by some new thing, the universe is really some other age, and by the way, faster than light travel is easily arranged, as demonstrated by this new machine that he or she invented.
Scientists don't work to prop-up theories, they are a bunch of jackasses that learn to understand the old because they have to, but, they would love to put their own stuff in its place. These people aren't stodgy old guardians of the scrolls of doom nearly as much as they are a bunch of sharks circling information, just waiting for that first bit of blood that suggests a hole in some established theory.
This is my sig.
Planetary. Planetary intergalactic. Another dimension!
...they are a bunch of sharks circling information, just waiting for that first bit of blood that suggests a hole in some established theory.Trying to poke holes in in established theories (also known as conducting experiments and analysing empirical data) is more properly called the scientific method. You make it sound like a bad thing, and that ivory tower guardians of cryptic scrolls are the true scientists. You have it all backwards. Theories shouldn't need propping up, they should stand on their own, and especially stand up to repeated scrutiny and analysis. If we failed to poke holes in established methodology there would be no Newton, no Einstein, no progress to speak of.
"lightweight electrons"????
For God's Sake! There really was nothing wrong with Bohr's atom was there?
I'm still trying to explain wave and particle theory to my pug dog, who gazes intently into my eyes!
Now I've got to try and explain electrons that don't 'weigh'(?) as much!
Don't be apathetic. Procrastinate!
I never advocated tossing GR out the window, it's way too successful and I have way too much investment in the math to reject it (as they say, nature abhors a second order differential equation, right?).
Don't be silly. MOND doesn't cover the regime of gravitational time dilation- and is in fact not at odds with GR. MOND and GR cover different regimes, MOND concerns itself with gravitational/inertial interactions at very small accelerations (of less than about 10^-10 m/s^2, ignoring the Hubble constant correction term).
The point is that we have a fundamental choice between believing that there's more mass that we can't detect by EM in the Universe than that which we can detect, or that we're missing a big piece of how gravity (or, if you prefer, inertia) works, or (of course) "something else." And the jury is absolutely still out.
While the physics community certainly favors the dark matter model right now, most will say that the door isn't shut on MOND yet. Dismissing anybody who mentions it as a crank is not reasonable and it's dishonest to try to put a Mr. Physics Authority Figure face on doing so - MOND papers are still published in indiscriminate rags like the Journal of Cosmology and Astroparticle Physics and tenure-holding proponents are seen in polite company that would shun cold fusion researchers.
I have no idea how many physics undergrads "really" know GR and QM - I suspect that most probably haven't gotten past the wave equation formulation or even heard of quantum field theory, and might or might not have had to sling a few tensors around in an elective - most probably don't do graduate computational cosmology work, either (even if it was back when having time on a Cray meant something). There's more money in commercial software, though.
"It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny
That's probably a typo, it should say intergelatic. That's something between ice creams.
To lose the intergalactic mass once might be considered a misfortune. To lose it twice begins to look like carelessness.
You know what they say about opinions. They're all fabulous!
I would be inclined to agree. Spitzer isn't really equipped to study the really interesting (longer) IR wavelengths. Nor is SOFIA. Unfortunately there doesn't seem to be a strong interest in an IR survey telescope. Perhaps a telescope on the far side of the moon would be a good idea but it seems likely that will be a decade or more away.