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Missing Matter... Still Missing
squidfrog writes "Nature.com, PhysicsWeb, and the BBC all report on the latest results from the Cryogenic Dark Matter Search. 'The most powerful search yet for the Universe's missing matter has come up empty handed, contradicting an earlier study that claimed to have seen new particles.' 'A favoured theory is that the dark matter consists of Wimps (weakly interacting massive particles) about a thousand times more massive than a proton, one of the particles found in an atom's nucleus... on the rare occasions a Wimp strikes an ordinary atom, the effect should be noticeable.' 'Writing in the Physical Review Letters, the team says that while a detection has yet to occur, there is now a better idea of how much dark matter must exist.' They 'hope to improve the sensitivity of the experiment by another factor of 20 over the next few years.' What's 20 times 0? And don't tell me zero!"
I think the answer to the dark matter problem and the quantum theory of gravity is one in the same. Our description of gravity is wrong. It has recently been discovered that dark matter is 'missing' from three elliptic galaxies. One would think that on the scale of something as big as a galaxy and with WIMPs being so massive that you ought to detect some quite major effect..
Add that to the fact that the universe's acceleration is getting quicker rather than slowing down and I think we have a strong case for our description of gravity being incorrect.
Simon.
A favoured theory is that the dark matter consists of Wimps (weakly interacting massive particles) about a thousand times more massive than a proton
My training in physics is quite elementary, but I was led to believe the proton is relatively massive on the atomic level, especially when compared to an electron. How could a wimp be so large and yet unnoticed?
An effective signature identifies a particular user amongst a base of thousands.
I don't know, even though science has a track record of proving (at the time) absurd claims, dark matter just seems.....silly. (I typed darl matter here as a typo, that would have led to yet another SCO thread I'm sure) What are the other theories about the missing mass? I'd like to shop around and see if I can find one a little more reasonable-sounding. :)
-1, "1337" speak
Comment removed based on user account deletion
This research, though, seems to be taking the same route: rather than questioning the model, they continue a so-far fruitless search for the "missing matter." If the model demands something the existence of which we are completely unable to verify, shouldn't we be questioning the model? Doesn't the very fact that there's all this "missing" matter indicate that perhaps our understanding is flawed?
Or am I just displaying rampant ignorance of the current state of physics and cosmology by asking this?
Reality has a conservative bias: it conserves mass, energy, momentum...
I am not a physicist, but I think the dark matter is a totally false idea fabricated to explain things we cannot explain with our current perception and knowledge of physics. It is similar to the aether idea that was fabricated to explain Maxwell's equations on a cosmological scale so they did not collide with Newton's theories. The more we figured out about the properties of the aether, the more magnificent it needed to be. Einstein realized that Newton's common sense laws were actually different than we perceived and rewrote physics by determining that the existance of the aether was incorrect, and what we observed was caused by relativity. I think the same holds true with dark matter. What we are observing is the effect of gravity traversing dimensions other than the four we normally encounter. The other eletromagnetic forces do not cross into these dimensions, but gravity does. This would also explain why gravity seems so much less powerful than the electromagnetic forces, it is spread out through multiple dimensions. We know there is a force somewhere and lots of it, but can see no evidence of it because it is beyond our perception. We only see the effect of gravity particles (gravitons) that are traversing into our dimension from the others. Perhaps there really is the aether all around us, and it is more spectacular than ever imagined. This aether would be multidimensional and be everywhere. We cannot see or cross the dimensions we are in into another one. But they are there on the other side of the aether. The gravitons pass right through it and that is what we observe.
Actually, the "dark matter" hypothesis agrees with practically every observation you can think of: x-rays from galaxy clusters, the rate of formation of large-scale structure, the formation of deuterium/helium/lithium in the Big Bag, the cosmic microwave background, gravitational lensing by large clusters, AND (of course) the familiar argument that 'the outer parts of galaxies rotate too fast)'. The only odd thing about the hypothesis, is the fact that the dark matter apparently interacts only very weakly: with photons, not at all, thus 'dark'; with gas, stars and planets hardly at all, thus the extended shapes of galactic halos; and with CDMS, too weakly to have been detected so far, apparently.
Weakly interacting particles shouldn't surprise us - think of neutrinos, no? - and indeed a very powerful theory called SUSY predicts the existence of dark matter, based on elementary particle physics constraints.
The idea that you can fix the 'dark matter problem' by modifying gravity is interesting, and it has been thought about a lot. It's hard to make any sort of theory agree with all of the measurements I mentioned. Google for "MOND" (Modified Newtonian Gravity" to learn more.
I find this quote interesting...
[Dark matter] is thought to come from a variety of heavy particles that rarely interact with regular matter and can pass through conventional objects unseen.
That sounds like another phenomena of a less scientific nature... ghosts! In some belief systems spirits or souls are more massive or dense then normal matter as well.
If this were true, I would suggest the reason that this experiment didn't find any "dark matter" is because there wasn't any in the vicinity, because the organization and distribution of this dark matter is neither even nor random.
Astronomers believe this arises from the gravitational effect of 'halos' of dark matter around spiral galaxies. (source)
Together, these two results suggest, to me anyway, that dark matter could really be more advanced civilizations or intelligences that we know nothing about.
I'm not a journalist, but I play one on slashdot
Opps. I meant, seven.
IBM may agree with you! Try this code on AIX:
#include"stdio.h"
int x,y,z;
int main() {
x=1;
y=0;
z=x/y;
printf("%d", z);
}
On most unix implementations you get floating point exception since the divide operator takes floating point operands. On AIX, when the denominator is cast to a float, it's a zero approximation rather than the official floating point zero. The result is that instead of a core dump, you get... 15.
Disconnect your television. Do your own research. Draw your own conclusions. They're probably lying. Don't be a sheep.
Only according to some sources 1/4th of the matter in the universe is dark matter. How can it not be undectable then if its this massive particle 1000x more dense then a proton?
I personally think its a lack of understand of space/time that creates the illusion of dark matter. The string theory could also prove that bends in the time/space contium alot like threades of lint in carpet exist. When light passes through them they amplify when they reach the bend.
There is alot of stuff in the 4th, 5th, and other dimensions that we do not know about.
http://saveie6.com/
One of the possible outcomes of string theory is multiple universes, each separated by a fairly small distance (of course this distance is in a higher dimension so we can't notice them). If these alternate universes do exist, it is thought that the gravity from particles in our universe affects the other nearby universes. Imagine our universe as a flat sheet and another universe is a parallel flat sheet close to ours. In this model, gravity would still be three dimensional - ie, it would be able to bridge the gap between universes and affect the other universe. Perhaps this is what we're noticing - the gravity of massive particles in another universe?
BTW, I am not a physist but I have read up on this stuff. The theory of gravity carrying over to other universes actually does make sense - it explains why gravity is so much weaker than the other forces, because much of gravity's effect isn't on this universe. There's experiments going on now to test and see whether this is actually the case but I don't know the outcome. Anyway, this is just my thought on perhaps why we can't detect the dark matter - because it's not physically in our universe.
but my bullshit detector has been pinged since this dark matter nonsense started. I have yet to see a single piece of credible evidence that shows the dark matter hypothesis is anything more than a hastily concocted attempt to explain why some physicists theories don't jive with experimental results. Just admit that you don't know why, rather than attempting to pass off a clearly inferior piece of intellectual flotsam as the next great thing. Show me some evidence, ANY evidence, and then you'll get my money.
* in DU there is no dark matter (if I understood right)
U %20Main.ht m
* DU is simpler than General Relativity
* DU predictions are close to GR, but differs slightly - those exceptions should be verified
* DU theory predicted also that the speed of light is getting slower - phenomenon found by Australian scientists lately
Check:
http://www.sci.fi/~suntola/DU,%20Main/D
The BBC Article says that: "This form of matter comprises more than 70% of the Universe's mass, far more than the stars and galaxies we can see." This is technically correct. The WMAP results are that 73% of the energy density of the universe is "dark energy." The remaining energy density is matter. From galactic rotation curves, gravitational lensing, etc. we suspect that dark matter accounts for around 80% of the matter (mass) in the universe.
"Actually the amazing this is that we CAN claim to be aware of the size of the universe! Since everything is accelerating away from us as the Universe apparently expands we can extrapolate this expansion back in time until all the matter in the observable Universe was at a point i.e. the Big Bang. Since we now have a time when the Universe began we now have a maximum size limit for the Universe ~ speed of light x age."
I said based on almost no facts, you haven't said anything here which challenges that. The big bang is a theory, that makes any facts determined based on when it happened a theory also. Your basing the starting point on pure theory. There are no facts in anything you've just said. And you certainly can't presume to impose proofs which rely on another contradictory theory on his theory.
"until all the matter in the observable Universe was at a point"
For a second let's pretend to give you the big bang. Now, you say we determine this from knowing when all matter we can presently observe was at a single point based on the rate of theoretical expansion that may or may not be happening. No matter how far we've looked, and been able to look, we've found more universe. So wouldn't it be fairly reasonable to believe it might just be a tad arrogant to believe that how far we can presently see is as far as can be seen?
And if so, what about the time it takes for the rest of the matter we CANNOT see yet to get back to this single point of yours? Ok, so now we've discovered that both the method by which you propose to gauge the size of the Universe and the Age are full of holes. And as you propose them are Paradoxically reliant upon one another. How can you determine the size of the universe by determining how long it would take for all of it to be retracted back to a single point, when you don't know the size and thus how far it stretches to begin with? Further how do you know the Universe expands at a constant rate (if it expands)?
If it accelerates, what makes you believe it accelerates at a constant rate. Unfortunately physics in the present day is full of these kinds of holes at almost every turn and is pretty shakey at best.
"Well that is not quite true. We can observe a tremendous amount of the Universe and we see no evidence for mass being created since creating mass from nothing would violate probably the most fundamental law of physics, namely conservation of energy. This conservation law is caused by invariance of all the physical laws (that we know of) under spatial translations. So in order to create matter/energy you would need to introduce a new physical law that does not hold the same for all spatial coordinates."
Yes, we have observed a tremendous amount of the Universe, relative to our perception of it. A field mouse on a hill might believe he's observed the entire world, or most of it, but that hardly makes it true. We have no way of knowing in fact the size of the Universe, and therefore have no way of knowing if that portion we know about constitutes a billionth of a percent of it, 50%, or even no percent in an infinite universe.
Further, nobody has proposed creating mass from nothing here, someone has however proposed that mass from another location is moved to this location. That in itself violates none of the fundemental laws of physics that I'm aware of.
"So while we cannot categorically rule out mass being created somewhere in the Universe it requires lots of new physics for which there is absoulely no evidence. Thus it is far more likely, given our current understanding, that mass is NOT being created and added to the Universe."
Odd, I was under the impression that about the only thing in physics we could be absolutely sure of was that mass was at one point created. After all it had to come from somewhere right?
An important fact regarding CDMS is that Dark Matter direct detection experiments are only just beginning to probe the sensitivities required to observe Dark Matter, according to the theorists. The most popular WIMP candidate, the neutralino, is predicted to exist anywhere from an order of magnitude above CDMS's current sensitivity, down to several orders of magnitude below. The WIMP is well-motivated, and sure - it might not exist - but that will tell us at least as much about the universe than if we were to find it.
There really is a huge amount of research that supports dark matter in some form or another. Read up before you criticize CDMS as being a white elephant experiment!
The assumption that "dark matter" exists is a common one based on (some of) the observations of the universe. Dark matter does not explain the increased rate of expansion of the universe at great distances. This requires another assumption - "dark energy" (or a positive "cosmological constant").
There are versions of M-theory which do not require one or both of these. There is also a theory, as yet unpublished (since it upsets physics journal editors), which eliminates the "clock hypothesis" and accounts for inflation and accelerated expansion. (One has to be careful to take each new (and old) theory in physics with a big grain of salt.)
Just as the biological community "sold" the human genome project as THE ANSWER (one gene = one protein) and is trying to sell the protein folding problem as the NEW ANSWER (and it is an important problem), the (majority of) the (astro)physics community is trying to sell "dark" (matter or energy). "Dark" may well exist. I believe that it is important to allow a variety of views in the physics community to be heard (i.e. published) and let scientists design experiments to test various hypotheses. The "popular" theory may (or may not) correspond to observations.
This is certainly true. Obviously, common sense needs to be applied. The only point I was initially trying to make is that the "20 times zero is what?" comment in the post was at best an exaggeration.
There definitely comes a point where these people should be told to fund it themselves if they're so keen on it, but a lack of results does not in and of itself guarantee that the notion is unsound. A whole bunch of conflicting results is another matter, but a lack of evidence isn't statistically significant(sample size is zero).
Actually, I take that back. The sample size of this technique is insufficiently large to reject the hypothesis on a result of zero. Given that it's made to detect inherently rare events, a size of 0 would be within its data scatter. There's probably a point at which they can state that if they're not detecting WIMP interactions, then WIMP - at least alone - can't account for all of dark matter(or the proportion they thought it did according to the hypothesis). They might be some of it, but other things will then need to be looked at.
In short: It's possible for a limit value(in this case, zero events) to not be statistically significant. Consider it as a truncated normal curve, with 0 within a few standard deviations. You have two basic ways to avoid the insignificant limit problem: increase the mean value, or decrease the standard deviation. The former is possible by making a more sensitive detector(which could simply be bigger), the latter by making it more precise(which would probably mean, among other things, covering a MUCH larger area and likely multiple sites, and is in general harder to accomplish if you aren't even quite sure what you're looking for outside of unproven math).
So, while WIMPs wouldn't be disproven by a lack of results, it could eventually be stated that, since a count of zero is no longer within the variance of the hypothesis and the instruments used to test it, a persistant zero count would mean that the WIMP count is significantly lower than the prediction of the hypothesis, so the hypothesis would need to be revised.
NB: YMMV. IANAL. Take the above with a grain of salt.
There seems to be a common sense here that all of the evidence for dark matter could be equivalently explained by changing the force law.
However, that isn't true. One unique test of dark matter is that it is dynamical; it can move. And there are a bunch of tests that have started to be made that show evidence for dynamical dark matter:
- in order to explain rotation curves without dark matter, models like MOND require force laws that would make the derived "shape" of the dark matter halo spherical at large radius. You can test this by looking at the shapes of clusters using X-ray emitting gas (eg. Buote et al. 2002, ApJ, 577, 183; Lee & Suto 2003, ApJ, 585, 151; Lee & Suto 2004, ApJ, 601, 599) or the Sunyaev-Zeldovich effect (LS03,LS04). You can also look at the shapes of dark matter halos around galaxies using weak gravitational lensing (Hoekstra et al. 2004, ApJ, 606, 67). So far all of the tests indicate that dark matter halos are not spherical, but flattened exactly as predicted by cold dark matter.
- the bars in barred spiral galaxies should slow down and disperse quickly in a spherical static halo potential, like you'd get from modifying the force law, but they can be maintained for long periods of time if they can exchange angular momentum with the dark matter (Athanassoula 2002, ApJ, 569, L83; Valenzuela & Klypin 2003, MNRAS, 234, 459).
- there's a weak gravitational lensing observation of a group that is falling into a cluster, where the mass of the infalling group is offset from the light - the gas is moving slower because it's interacting with the cluster gas, while the dark matter has kept moving (Clowe et al. 2004, ApJ, 604, 596).
[TMB]
So if that's a goal of ours, perhaps it's a goal of another race's. And perhaps they got a head start on us, and that large percentage of "dark matter" actually consists of Dyson Spheres which capture everything, so are "undetectable" by us. That's pretty scary, to think that we just lost that much playground, and will eventually have to deal with the bully--on his own terms perhaps.
I mentioned this a year ago or so, and someone pointed me in the direction of Matrioshka Brains, so I will include some links for that as well. And an excellent discussion.
I would add to the last part that the larger planets could be taken apart by space elevators as well. They'd just start with the upper atmosphere; then work their way down. All the time the mass is getting smaller, and the elevators are pulling mass out so they can make themselves bigger in order to reach deeper. I think it's workable, and appears to be the most efficient way to do it--get the mass all out into "orbit" first. Actually, when you're about halfway done you can then start shipping what you mine off to other locations, and taking that amount of mass out of the elevators as well since they won't need to counterbalance as the planet's now smaller. (I don't know what the mathematical "middle point" where you start dismantling the elevators actually is--it could be something other than 50%.)
We could have "planet splitter seeds" which we shoot off to other stars, and they start with a tiny, correctly-placed elevator and build more of them as fast as is physically possible; the seed would be smart enough to calculate all the masses and start with the most effective one that would lead to the earliest date at which the entire mass of the star system is being used for computation.
The only problem is if we encounter life. Will our machines just assimilate it? Are the ones out there programmed to preserve us? Have they already done so?
I feel fantastic, and I'm still alive.