Highly Sensitive Dark Matter Experiment Disproves Earlier Findings

May 06, 2010
Light sensors making up the lower detector on the XENON experiment. Image credit: Guillaume Plante

(PhysOrg.com) -- Early data from a Columbia-led dark matter experiment rule out recent hints by other scientists who say they have found the elusive particle that holds the universe together. The findings show that dark matter, which is believed to make up 83 percent of the matter in the universe, is more elusive than many had hoped.

" continue to escape our instruments, yet we are getting much more clever in our search and feel confident that we will soon unveil them," said Elena Aprile, spokesperson of the XENON100 experiment and a professor of physics at Columbia University.

Aprile and her collaborators, who number more than three dozen physicists at nine institutions around the world, presented their findings at a workshop on May 1 and have submitted a paper to the journal . The scientists, whose experiment is the most sensitive search for dark matter to date, plan to release a much larger set of data over this summer.

The group did not expect to find dark matter in this short run of data taken last fall. Instead, their results show that the detector is better than any other at screening out that can be mistaken for the elusive particles.

The hunt for dark matter has become highly competitive in recent years, with more researchers entering the field. In 1997, the DAMA/LIBRA research group of the University of Rome Tor Vergata became one of the first to claim it had found dark matter. This past February, the CoGeNT collaboration lead out of the University of Chicago, announced that it, too, had found a signal indicative of dark matter.

The new results from XENON100 cast doubt on both of these findings. If the earlier signals were due to dark matter, XENON100 would have seen dozens of events—unless the properties of dark matter are very different than expected.

Scientists first suggested the existence of dark matter in the 1930s to explain how keep from breaking apart as they spin. Like merry-go-rounds, galaxies generate centrifugal force as they rotate. Gravity is the glue that holds stars and galaxies together, but there isn't enough visible matter in the universe to generate the amount of gravity needed to keep galaxies from tearing apart. That's why scientists believe there must be additional, unseen matter out there. Scientists working on XENON100 believe that dark matter is made up of new elementary particles called Weakly Interacting Massive Particles, or WIMPS, which rarely bump into normal matter.

Aprile and her colleagues have been working on XENON100 since 2007 as part of a project funded largely by the National Science Foundation. Their detector, which was built at Columbia, consists of a stainless steel container filled with ultra-pure liquid xenon sandwiched between two highly sensitive cameras. It is located beneath 5,000 feet of rock in Italy's Gran Sasso Underground Laboratory (LGNS) in a chamber of lead and copper that, along with the rock, helps filter out cosmic and background radiation that may otherwise be mistaken for WIMPS.

Should a dark matter particle come into contact with a xenon atom, it will transfer a tiny amount of energy that will trigger the emission of a flash of ultraviolet light that the cameras will pick up. The energy also manifests itself in a small amount of electrical charge—weaker than that produced by the passage of other known particles. If the XENON100 detector registers these light and charge signals and can exclude with high certainty that they were produced by other sources, it will be a strong indication that Aprile’s team has found dark matter.

The Columbia researchers use liquid xenon because it is one of the heaviest elements in the periodic table; at three times the density of water, it has many atoms per liter, maximizing the chances that a WIMP will collide with it.

“Liquid xenon is a precious and wonderful material for catching and studying WIMPS,” said Aprile, who has worked with the liquid for most of her research career.

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El_Nose
4.2 / 5 (5) May 06, 2010
If i were to guess as to the point of this article -- WHICH WAS NOT STATED -- it would be that the detector did not register any events at all while being observed.
LuckyBrandon
1.9 / 5 (11) May 06, 2010
but there isn't enough visible matter in the universe to generate the amount of gravity needed to keep galaxies from tearing apart

why would you need visible matter when you have that super suction from the supermassive black hole in the middle of the galaxies??
THoKling
3.5 / 5 (2) May 06, 2010
It may be suggested that black holes have already been accounted for in measuring the forces on our galaxy. We're always finding new developments in physics, though, and may find dark matter to be represented by something other than WIMPs.
Alizee
May 06, 2010
This comment has been removed by a moderator.
TimESimmons
1 / 5 (9) May 06, 2010
they're looking in the wrong place

http://www.presto...ndex.htm
solrey
1 / 5 (8) May 06, 2010
Dark matter was postulated to account for the failings of the gravity only model in regards to observations of galaxy clusters. It was invoked to save an otherwise falsified theory.

The universe is 99% plasma. Almost all of the "gas" in galaxies is ionized and therefore plasma. Models that include plasma, electromagnetic and electrostatic forces produce results that match observations of the universe, including but not limited to galactic rotation curves and the motions of galaxies in clusters.

As long as cosmologists ignore those simple facts, they will forever be chasing the phantoms of theoretical mathematics like dark matter and wasting a lot of money in the process.

Dark Matter Recreations parts I and II:

http://thunderbol...ions.htm

http://thunderbol...ons2.htm
Gyuri
1 / 5 (4) May 06, 2010
What if everything is composed of Priordial particles, P-particles, that are solid, undividable, frictionless, inelastic spheers.Single P-particles interact with mass with no energy loss. In that case, they cannot be detected.
jsa09
1 / 5 (5) May 06, 2010
but there isn't enough visible matter in the universe to generate the amount of gravity needed to keep galaxies from tearing apart.


I still think that it is not surprising if most of the matter in the universe is not "visible". Sure we have super massive black holes in the center of Galaxies and there is no reason why we may not have many much smaller invisible black holes orbiting inside the galaxy. One single black hole could hold more mass than all the visible mass in the universe and there could even be more than one.

@solrey I tend to agree with you that more weight and consideration should be given to other means of stiring the galactic pots. Electromagnetism which is thousands of times more powerful than gravity could do this job with ease with very small charges
KBK
1.4 / 5 (9) May 06, 2010
ELECTRIC UNIVERSE

ELECTRIC UNIVERSE

ELECTRIC UNIVERSE

When will they retire that old dead gravity horse?
thermodynamics
3.1 / 5 (9) May 07, 2010
Here is an interesting quote from the article: "The Columbia researchers use liquid xenon because it is one of the heaviest elements in the periodic table; at three times the density of water, it has many atoms per liter, maximizing the chances that a WIMP will collide with it."

Does anyone see anything wrong with it? The answer is that they are making it appear that it has more atoms than, say, liquid helium or liquid water at the same temperature (of course neither would be liquid at the same temperature but you get the idea they are implying it has more atoms per liter because it is more dense than water). The reality is that it is more dense than water because it has an atomic weight of 131.3 whereas water has a molecular weight of about 18. Oops, it is more dense, not because it has more particles in it, rather because they are heavier. And, the real reason it is used is because of its larger collision cross section.
CaptBarbados
May 07, 2010
This comment has been removed by a moderator.
Ravenrant
3 / 5 (4) May 07, 2010
You can't find something that doesn't exist and I still think it doesn't, I think it's more likely that we have a fundamental misunderstanding of some physics.
kevinrtrs
1.4 / 5 (9) May 07, 2010
So perhaps one needs to also ask the question: Just how has it been determined that there is less mass than there should be? Was that initial theoretical calculation correct? What if they has somehow made a mistake and computed a ratio that does not hold up to reality in the first place? What are the underlying assumptions and should they not perhaps be re-visited?
Please do not flame me on this - it's a genuine question seeing that the physicists seem to be chasing their own tails here. In fact it really, truly appears like the emperor's clothes - no one can see it!

Shootist
1.6 / 5 (7) May 07, 2010
It may be suggested that black holes have already been accounted for in measuring the forces on our galaxy. We're always finding new developments in physics, though, and may find dark matter to be represented by something other than WIMPs.


I suspect we have undercounted singularities, rogue planets, brown dwarfs, gas and dust. Dark matter is probably just that, Dark, as in not seen, baryonic matter.

Time will tell.
lengould100
5 / 5 (5) May 07, 2010
So perhaps one needs to also ask the question: Just how has it been determined that there is less mass than there should be? Was that initial theoretical calculation correct? What if they has somehow made a mistake and computed a ratio that does not hold up to reality in the first place? What are the underlying assumptions and should they not perhaps be re-visited?
Please do not flame me on this - it's a genuine question seeing that the physicists seem to be chasing their own tails here. In fact it really, truly appears like the emperor's clothes - no one can see it!



The original problem is that the stars which make up a galaxy are orbiting round the galaxy's centre faster than the gravity generated by all the identified matter in the galaxy can counterbalance, by a significant factor.
baudrunner
1.3 / 5 (9) May 07, 2010
Physicists are neglecting to account for the breakdown of classical physics in dealing with the colossal scale. We can't apply the rules on the macro scale to the quantum realm, neither can we apply them to the colossal. What we expect to see happening probably is, but from within its own temporal relative context.
CWFlink
3 / 5 (2) May 07, 2010
....
The original problem is that the stars which make up a galaxy are orbiting round the galaxy's centre faster than the gravity generated by all the identified matter in the galaxy can counterbalance, by a significant factor.


Curiosity demands I ask: How fast do stars orbit the galactic center relative to their distance from us and from center? We are looking back in time due to the distance as well as dealing with relativistic time shifts due to the speed. Then add in the "expanding universe" ... the calculations must be quite a challenge. A first cut would assume a stable orbit, but the only stable orbits would be very close to the black hole, which means these times only reflect the mass in the hole, not the total "dark matter" in the galaxy which is presumed to be distributed broadly. This has got to be a very difficult many-body problem in an expanding plasma!
Alizee
May 07, 2010
This comment has been removed by a moderator.
zslewis91
3.6 / 5 (7) May 07, 2010
"thunderbolts.info"? "Anti-Gravity Matter"?! wow, you people are lost...A series of jokes that you call thought...small minds without purpose, subject matter beyond your comprehension...in other words, if you cant do, or at least understand the math behind the words...dont comment.your making yourself's seem and sound..... retarded
Alizee
May 08, 2010
This comment has been removed by a moderator.
Alizee
May 08, 2010
This comment has been removed by a moderator.
frajo
5 / 5 (4) May 08, 2010
So we can imagine, the dark matter is formed by area of weak negative curvature of space-time outside of massive objects and positrons,
There's a lot one can imagine. But the essential criterion is whether your imaginations are falsifiable.
Alizee
May 08, 2010
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Alizee
May 08, 2010
This comment has been removed by a moderator.
pbfred
1 / 5 (4) May 09, 2010
You can't find something that doesn't exist…I think it's more likely that we have a fundamental misunderstanding of some physics.

We have had to make a serious change of fundamentals in physics in the past. This is when we went from the Ptolemaic geocentric view to the Copernican heliocentric view. The Ptolemaic view was supported by the earth rotating on its axis which gave the appearance that all objects in the sky rotated around the earth daily. We have evidence that mass mediates the gravitational force. Could this evidence be based on a misleading artifact that only gives the appearance that mass attracts mass or warps space? I have performed 5 experiments which show that the heat due to the radiation leaving mass is gravitationally attractive. To see them and my paper go to: http://vixra.org/abs/0907.0018 . We should have asked ourselves long ago: Is it the sun’s mass or its luminosity that attracts the planets or the earth’s mass or its heat that attracts the moon.
pbfred
1 / 5 (3) May 09, 2010
You can't find something that doesn't exist…I think it's more likely that we have a fundamental misunderstanding of some physics.

We have had to make a serious change of fundamentals in physics in the past. This is when we went from the Ptolemaic geocentric view to the Copernican heliocentric view. The Ptolemaic view was supported by the earth rotating on its axis which gave the appearance that all objects in the sky rotated around the earth daily. We have evidence that mass mediates the gravitational force. Could this evidence be based on a misleading artifact that only gives the appearance that mass attracts mass or warps space? I have performed 5 experiments which show that the heat due to the radiation leaving mass is gravitationally attractive. To see them and my paper go to: http://vixra.org/abs/0907.0018 . We should have asked ourselves long ago: Is it the sun’s mass or its luminosity that attracts the planets or the earth’s mass or its heat that attracts the moon.
pbfred
1 / 5 (3) May 09, 2010
We have had to make a serious change of fundamentals in physics in the past. This is when we went from the Ptolemaic geocentric view to the Copernican heliocentric view. The Ptolemaic view was supported by the earth rotating on its axis which gave the appearance that all objects in the sky rotated around the earth daily. We have evidence that mass mediates the gravitational force. Could this evidence be based on a misleading artifact that only gives the appearance that mass attracts mass or warps space? I have performed 5 experiments which show that the heat due to the radiation leaving mass is gravitationally attractive. To see them and my paper go to: http://vixra.org/abs/0907.0018 . We should have asked ourselves long ago: Is it the sun’s mass or its luminosity that attracts the planets or the earth’s mass or its heat that attracts the moon.
pbfred
1 / 5 (3) May 09, 2010
We have had to make a serious change of fundamentals in physics in the past. This is when we went from the Ptolemaic geocentric view to the Copernican heliocentric view. The Ptolemaic view was supported by the earth rotating on its axis which gave the appearance that all objects in the sky rotated around the earth daily. We have evidence that mass mediates the gravitational force. Could this evidence be based on a misleading artifact that only gives the appearance that mass attracts mass or warps space? I have performed 5 experiments which show that the heat due to the radiation leaving mass is gravitationally attractive. To see them and my paper go to: http://vixra.org/...07.0018. We should have asked ourselves long ago: Is it the sun’s mass or its luminosity that attracts the planets or the earth’s mass or its heat that attracts the moon.
daywalk3r
4.1 / 5 (17) May 09, 2010
We have evidence that mass mediates the gravitational force. Could this evidence be based on a misleading artifact that only gives the appearance that mass attracts mass or warps space? I have performed 5 experiments which show that the heat due to the radiation leaving mass is gravitationally attractive .. We should have asked ourselves long ago: Is it the sun’s mass or its luminosity that attracts the planets or the earth’s mass or its heat that attracts the moon.
No, I think you should go find a different hobby..

"Spiritual healer" or "conspiration theorist" would fit quite well I believe.. Just a tip ;-)
CyberRat
1 / 5 (2) May 09, 2010
CyberRat
1 / 5 (3) May 09, 2010
ZeroX
2.3 / 5 (3) May 10, 2010
Is it the sun's mass or its luminosity that attracts the planets or the earth's mass or its heat that attracts the moon.
How do you want to explain the fact, hot ballon is attracted to Earth with smaller force, then this cold one? Such theory doesn't appear viable for many cold planets and moons, which should separate because lack of gravity, if your theory is right.
pbfred
1 / 5 (2) May 11, 2010
ZeroX @"How do you want to explain the fact, hot balloon is attracted to Earth with smaller force"
I do not deny that hot air rises. For an increase in weight to occur, heat must transfer through the test mass. Thus I use a copper test mass which readily conducts heat. A hot air balloon has cover that is not very conductive.
Cold planets and moons orbit around some body that is hotter than they are. This heat from the central body could collect at the center of these satellites.
daywalk3r
3.9 / 5 (14) May 11, 2010
For an increase in weight to occur, heat must transfer through the test mass. Thus I use a copper test mass which readily conducts heat..
Actually.. IF we just virtually consider the internal molecular/atomic kinetic energy of an object (thermal energy) as adding up to its total rest mass (by m=E/c2), then an increase in temparature should indeed cause an increase in the gravitational pull of the object in question, though of a very miniscule amplitude and only IF the thermal energy came from an external source (eg. no "self-heating" by decay/fusion/etc.)..

But we are talking about differences on the order somewhere in the realm of 1e-100 percent per Kelvin maybe (feel free to do the calculations and correct me if I'm wrong, it was just a mere guess :) And it would only be true IF gravity was caused by the total energy potential, and not only by rest mass.

We can talk IFs all day long :)
pbfred
1 / 5 (3) May 12, 2010
In my paper I quote a remark of Einstein that he made in 1950:
"Now we may reverse the relation that an increase of E in the amount of energy must be accompanied by an increase in E/c^2 in the mass. I can easily supply energy to the mass--for instance if I heat it by 10 degrees. So why not measure the mass increase.... The trouble here is that in the mass increase, the enormous factor of c^2 occurs in the denominator of the fraction. In such a case the increase is too small to be measured"
In my experiments I can easily measure a gravitational mass increase. In my way of thinking they represent what is called a "serious anomaly" similar to that associated with the results of the photoelectric effect or Rutherford's gold foil experiments. They question Einstein's interpretation of E=mc^2 and the validity of the equivalence principle upon which the theory of GR rests. But I am an amateur and because of this, my results are less real and thus are not meant to be paid any attention to.
Skeptic_Heretic
5 / 5 (2) May 12, 2010
Relative mass and absolute mass are wholly different things. Without that understanding, you cannot follow Einstein's postulates.

Remedial physics for you leadfred.
pbfred
1 / 5 (3) May 15, 2010
The principle of equivalence is only valid if you first specify that the amount of heat transferred trough the test mass in outer space is the same as when that test mass is placed on the surface of the the earth in a falling elevator.
Say you have a convex-up copper hemisphere located right above a 1000 W heat element in outer space. That hemisphere should tend to move towards the heat element according to my experiments. However if you place the same hemisphere without the heat element on a falling elevator that is located on the surface of the earth, you should not be able to detect any force on it at all. As the principle of equivalence is stated in text books and on the web, nowhere is it specified that the amount of heat transferred has to be constant in both outer space an in the falling elevator. You have not commented on my experiments. What,in your mind they do not exist? They may run counter to what the textbook says. But that does not mean necessarily they are invalid.
Skeptic_Heretic
5 / 5 (1) May 15, 2010
You have not commented on my experiments. What,in your mind they do not exist? They may run counter to what the textbook says. But that does not mean necessarily they are invalid.

They're invalid because you cannot account for any control in them.

If reality was as you said and thermal energy was the sole source of gravitation then by the math Venus would have pulled the Earth into the sun during accretion. Above and beyond that, none of the satelites that are making this conversation possible would be in orbit.

Like I said, remedial physics.
Alizee
May 15, 2010
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