Plenty of dark matter near the Sun

Aug 09, 2012
The high resolution simulation of the Milky Way used to test the mass-measuring technique. Credit: Dr A. Hobbs

(Phys.org) -- Astronomers at the University of Zürich, the ETH Zurich, the University of Leicester and NAOC Beijing have found large amounts of invisible "dark matter" near the Sun. Their results are consistent with the theory that the Milky Way Galaxy is surrounded by a massive "halo" of dark matter, but this is the first study of its kind to use a method rigorously tested against mock data from high quality simulations. The authors also find tantalising hints of a new dark matter component in our Galaxy. The team's results will be published in the journal Monthly Notices of the Royal Astronomical Society.

Dark matter was first proposed by the Swiss astronomer Fritz Zwicky in the 1930s. He found that clusters of galaxies were filled with a mysterious dark matter that kept them from flying apart. At nearly the same time, Jan Oort in the Netherlands discovered that the density of matter near the was nearly twice what could be explained by the presence of stars and gas alone. In the intervening decades, astronomers developed a theory of dark matter and structure formation that explains the properties of clusters and galaxies in the Universe, but the amount of dark matter in the solar neighbourhood has remained more mysterious. For decades after Oort's measurement, studies found 3-6 times more dark matter than expected. Then last year new data and a new method claimed far less than expected. The community was left puzzled, generally believing that the observations and analyses simply weren't sensitive enough to perform a reliable measurement.

In this latest study, the authors are much more confident in their measurement and its uncertainties. This is because they used a state-of-the-art simulation of our Galaxy to test their mass-measuring technique before applying it to real data. This threw up a number of surprises. They found that standard techniques used over the past 20 years were biased, always tending to underestimate the amount of dark matter. They then devised a new unbiased technique that recovered the correct answer from the simulated data. Applying their technique to the positions and velocities of thousands of orange K dwarf stars near the Sun, they obtained a new measure of the local dark matter density.

Lead author Silvia Garbari says: "We are 99% confident that there is dark matter near the Sun. In fact, our favoured dark matter density is a little high. There is a 10% chance that this is merely a statistical fluke. But with 90% confidence, we find more dark matter than expected. If future data confirms this high value, the implications are exciting. It could be the first evidence for a "disc" of dark matter in our Galaxy, as recently predicted by theory and numerical simulations of galaxy formation. Or it could be that the dark matter halo of our Galaxy is squashed, boosting the local dark matter density."

Many physicists are placing their bets on dark matter being a new fundamental particle that interacts only very weakly with normal matter -- but strongly enough to be detected in experiments deep underground where confusing cosmic ray events are screened by over a kilometre of solid rock.

An accurate measure of the local dark matter density is vital for such experiments as co-author Prof. George Lake explains: "If dark matter is a fundamental particle, billions of these particles will have passed through your body by the time your finish reading this article. Experimental physicists hope to capture just a few of these particles each year in experiments like XENON and CDMS currently in operation. Knowing the local properties of is the key to revealing just what kind of particle it consists of."

Explore further: Can astronomy explain the biblical Star of Bethlehem?

More information: The new work appears in: "A new determination of the local dark matter density from the kinematics of K dwarfs", Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper is available from arxiv.org/pdf/1206.0015v2.pdf

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chardo137
3.9 / 5 (14) Aug 09, 2012
Zwicky's dark matter was not taken seriously for many years. Because of this he said that his colleagues were "spherical ass-holes" since no matter how you looked at them they were the same. He spent most of his career at cal-tech, and was important in funding the Palomar observatory during the depression.
verkle
2.3 / 5 (19) Aug 09, 2012
Either dark matter really exists (which still seems unlikely), or else the models we have for galaxial size interaction of matter are not correct (this also seems unlikely, but possible). Of course, there could always be a third possibility. That is the exciting part of science.

antialias_physorg
4.4 / 5 (25) Aug 09, 2012
Either dark matter really exists (which still seems unlikely)

It exists. Dark Matter is a placeholder and as such can take on any form. You can model things in amyn different ways and get to the same result (an example would be gluons, gravitons, and even photons which can be modeled as 'entities that mediate a force' but also as probability densities).

The dark matter model 'just' says that there is something that is weakly interacting and acting like it has mass (e.g. WIMPS). Both these properties are 'observed' (or rather have been modelled from discrepancies in observation and measurement of how 'real' mater behaves).

That still fits many different ways of looking at dark matter - bei it particles, localized spacetime curvature due to something besides matter or whatnot.
philw1776
3.5 / 5 (15) Aug 09, 2012
90% certain. Particle physics needs 5 sigmas for "discovery". Astronomy, not so much.
Still count me in as a dark matter adherent because many independent observations at radically differing distances all indicate invisible mass.
evercurious
2.2 / 5 (5) Aug 09, 2012
reminds me of the square root of -1

Sometimes you just need something impossible to make the formulas work.
HannesAlfven
1.4 / 5 (21) Aug 09, 2012
Re: "We are 99% confident that there is dark matter near the Sun."

This attempt to quantitate the uncertainty of the inferential step requires that we all pretend as though philosophy of science does not exist. How, for instance, can statistics be used to measure the degree of our ignorance? If we don't know what we don't know, then what in the world does 99% confidence mean?

Re-antialias_physorg: "It exists. Dark Matter is a placeholder and as such can take on any form."

There are ramifications to us pretending like mainstream science will be proven right no matter what: For instance, fast-forward to the point in time when we figure it out. In retrospect -- in the event that their approach is determined to be highly flawed -- this view of science will be used to justify historical revisionism to make the process appear linear to future students. If the truth is that mistakes were made, we'd be wise to be clear about it so that future students can learn from those mistakes.
krundoloss
3.9 / 5 (12) Aug 09, 2012
I will be glad when this dark matter and dark energy stuff gets resolved. It seems as though the "dark" entities we are discussing simply represent our ignorance directly! Could it not be that there is a feature of gravity or space which eludes us, and causes the expected amount of gravity to differ from the observed amount? Wait, I just described dark matter/energy. We will figure it out one day, until then we will come up with dark placeholders......
xX_GT_Xx
4.6 / 5 (9) Aug 09, 2012
Re: "We are 99% confident that there is dark matter near the Sun."

This attempt to quantitate the uncertainty of the inferential step requires that we all pretend as though philosophy of science does not exist. How, for instance, can statistics be used to measure the degree of our ignorance? If we don't know what we don't know, then what in the world does 99% confidence mean?


Good lord. Statistics 101. Talk about not knowing what you don't know.
eric96
1 / 5 (6) Aug 09, 2012
I ask 2 Questions:

When Particular Accelerators collide two particles and these break into their constituents; does the mass of the constituents come close to the mass of the 2 particle prior to collision? If it doesn't then either the detector needs to be improved or there is Dark Matter.

If we think of a black hole as a particle accelerator ( I do ), the question is not so much what particles black holes are capable of creating, but rather how small of particles can a black whole like the one at the center of our galaxy create? This is a fierce question to answer, but the most important. Now, when I say create I mean the following: break into the smallest constituents (how small is that theoretically by measurement of relative gravity, and I imply that at some point this aka as Dark Matter henceforth escapes black holes (we see Gamma Radiation, but the majority of it is Dark Matter.)

God would not let us solve this problem easily. He would add cryptography (gamma rays).
kornus
5 / 5 (3) Aug 09, 2012
Now we know why Rama went so close to the sun. Harvesting dark matter, off course!
Parsec
4.8 / 5 (12) Aug 09, 2012
@HannesAlfvin - I have no idea where you learned YOUR history of science, but the history I learned is replete with various journeys into blind alleys (alchemy?), mass delusion ('F' rays), and other non-linear processes. The long standing phlogiston theory of combustion lasted for a long time before the discovery of oxygen laid it to rest. It is a modern popular myth that science proceeds in a linear fashion, and any scientist suggesting such a thing would be laughed out of the room.

However, I also disagree 'antialias_physorg' in at least one point. There are really 2 possibilities to reconcile the data. Dark matter or MTOG (modified theory of gravity). They are quite different. Dark matter simply posits some particle, MTOG posits modification in Einstein's theory of relativity and the actual property of spacetime. This are completely different things.
antialias_physorg
4.3 / 5 (6) Aug 09, 2012
Dark matter or MTOG (modified theory of gravity).

As long as they explain the observed they are not.

Now when you get to what they *predict*, then we get to differences (and of course that is where it gets interesting, because then you can decide which one we'll use). But currently - without a way to test between the two - they are equally 'good'.

It's a bit like with ecpicycles: They are a perfectly good way of modeling orbits. Epicycles are arbitrarily correct (for arbitrarily large numbers of epicycles). Heck, you can model the universe with the Earth at the center if you feel like it (and it would get you the same results, though the math would be more difficult)

But when all is said and done: No theory in the past has ever stood the test of time. And I expect similar for the current theories (including relativity and QM). As understanding deepens so will our theories grow more elegant/unified.
chardo137
1.7 / 5 (6) Aug 09, 2012
A very interesting theory can be found by looking up the Gravitational Polarization of the Quantum Vacuum. It is very interesting, and comes from serious physics, not crackpots.
kochevnik
1 / 5 (14) Aug 09, 2012
Dark matter is simply higher-dimensional space being rotated into phase such that mass is detectable. Planets, for example, generate hydrogen atmospheres via their gravity.
sanita
1.4 / 5 (10) Aug 09, 2012
Dark matter is simply higher-dimensional space being rotated into phase such that mass is detectable. Planets, for example, generate hydrogen atmospheres via their gravity.
The first sentence has some meaning for me -but how did you get into second one?
We are 99% confident that there is dark matter near the Sun
I'm 99% confident, that this dark matter is forming sparse but large atmosphere of cold neutrinos, which are getting heated with fast neutrinos emanated from Sun core, which induces the changes in decay rates of radioactive elements inside of various space-probes. The Sun is behaving like sorta hidden neutrino pulsar, so to say.
kochevnik
1.3 / 5 (14) Aug 09, 2012
Dark matter is simply higher-dimensional space being rotated into phase such that mass is detectable. Planets, for example, generate hydrogen atmospheres via their gravity.
The first sentence has some meaning for me -but how did you get into second one?
The phases of matter are literally phases of rotation of the hyperdimensional nuclei. Space appears inert and isotropic because it is so out of phase that it doesn't interact with our bodies. Gravity wells impart a rotation onto this phase, making some space 'matter' condense into the lightest phase of matter - hydrogen. That's why there are so many massive hydrogen gas planets, and why all planets have atmospheres.
antialias_physorg
5 / 5 (12) Aug 09, 2012
The phases of matter are literally phases of rotation of the hyperdimensional nuclei.

And this theory is based on... ?

There are a lot of words in there, which make sense taken indvidually. But the way you string them together into sentences just makes it sound like mumbo-jumbo out of a third rate Star Trek episode.
sanita
1.4 / 5 (9) Aug 09, 2012
IMO the rational core of your hypothesis is in fact, some materialization of dark matter was observed around core of Milky Way galaxy in form of 512 keV positron signal. Note that steady state universe model would require the spontaneous formation of matter from dark matter clouds for to counterbalance the radiative evaporation of matter. So I'm rather convenient with this idea. But IMO this theory would have problem with fact, the small planets have lower content of hydrogen, than the large ones and IMO you're exaggerating the scope of dark matter baryogenesis to much.
..the phases of matter are literally phases of rotation of the hyperdimensional nuclei.
This idea bears some resemblance with E8 theory of Lissi Garrett, but I'm afraid, he has his theory way better formalized than you already. This model is so abstract, that it's impossible to get some testable predictions from it.
HannesAlfven
1.7 / 5 (11) Aug 09, 2012
@Parsec - You are fortunate to have studied history of science. I'm an engineer and have had to learn it on my own time, because the university system (even CMU) does not place enough importance on the subject to teach it to engineers. If you go to communities of engineers -- such as Slashdot -- you will observe the overwhelming, simplistic view that history of science is linear.

But, to some extent, we are all victims of this. How many of us -- for example -- are familiar with the history of plasma physics (which I've discovered is extremely rich and controversial), or aether (which you will *never* find covered in any depth in any university textbook)? We are only taught the "end results" of these controversies, which for many lends the appearance that they were essentially linear progressions.
Benni
1.9 / 5 (9) Aug 09, 2012
It was a bit curious to me that they discussed almost nothing about their "detection methodology". All mass has gravity & I was expecting a discussion somewhere in the body of the discussion that they had discovered that gravity in the region of our Sun has now measured to be much higher than originally thought.

We know what the mass of the Sun is, from that or any other object the force of gravity can be calculated, this is how it has been determined the universe is somehow "missing mass" because there is an excess of gravity as compared to the observable mass for generating all that extra gravity.

In short, it was a hard article to read to figure out how much "dark matter" actually exists in the region of our Sun.
barbarina
4.5 / 5 (8) Aug 09, 2012
Fritz Zwicky was a scientific prophet who pronounced the amazing theory of Dark Matter in the 1930s and was the Father of Gravitational Lensing, Sky Survey Technique, Supernovae Search, in addition to patented inventions as the Underwater Ram Jet for the US Navy and JATO. He never directed the spherical label toward any one individual but was addressing the spherical nescience to the truth by a hostile scientific community, resistant to a paradigm shift. Throughout history, pioneers as my father have always encountered resistance to change and innovation, especially when it highlights the deficits and professional jealousy of those in the hierarchy of astrophysics and the sciences, who seek to portray themselves as scholars, but who are a scourge and hindrance to scientific advancement. Fritz Zwicky was a Renaissance luminary, who boldly forged ahead into the unknown universe, with a mind so brilliant that the standard intellect could only falter in its presence.
Jeddy_Mctedder
1 / 5 (3) Aug 09, 2012
but that's the whole point.....is dark matter a semantic identifier of phenomena not yet explained, or is it something specific that is explained but we just cannot 'see' yet. i vote for the fom

Either dark matter really exists (which still seems unlikely)

It exists. Dark Matter is a placeholder and as such can take on any form. You can model things in amyn different ways and get to the same result (an example would be gluons, gravitons, and even photons which can be modeled as 'entities that mediate a force' but also as probability densities).

The dark matter model 'just' says that there is something that is weakly interacting and acting like it has mass (e.g. WIMPS). Both these properties are 'observed' (or rather have been modelled from discrepancies in observation and measurement of how 'real' mater behaves).

That still fits many different ways of looking at dark matter - bei it particles, localized spacetime curvature due to something besides matter or whatnot.[/qr
dogbert
2.1 / 5 (18) Aug 09, 2012
Astronomers at the University of Zürich, the ETH Zurich, the University of Leicester and NAOC Beijing have found large amounts of invisible "dark matter" near the Sun.


The continual announcement that someone has found dark matter is becoming tiresome. This is just another recognition that our theories of gravity do not predict the movements of stellar objects followed by the kludge of dark matter.

No dark matter was found. Only the gravitational anomalies.

Scientists should attempt to be honest.
antonima
3.2 / 5 (6) Aug 09, 2012
Anyone remember the article about that Czech/Slovak/Austrian physicist that asserted dark matter is mostly just polarized vacuum fluctuations?
SatanLover
1 / 5 (5) Aug 09, 2012
are they talking about the bucky balls they found recently?
nuge
4 / 5 (8) Aug 09, 2012
reminds me of the square root of -1

Sometimes you just need something impossible to make the formulas work.


I can assure you that the square root of -1 is no more impossible or less a real aspect of the universe than -1 itself. It is just a member of a particular set of numbers that can be used to describe things, as all numbers are. It is just unfortunate that it is called an imaginary number...it gives people the wrong idea.
Urgelt
3.6 / 5 (7) Aug 09, 2012
It does seem to me that some folks are eager to jump from "measurement anomaly" to "invisible, weakly-interacting but massive particles." That may well be a correct leap to make, but there is no evidence for it yet, and there are other explanations in contention (for which there is no evidence, either). Or the measurement anomaly might have some explanation nobody has yet dreamed up.

I like Anti's phrasing. "Dark matter" is a placeholder, just a term for an unexplained phenomenon. The phenomenon is real. It's been confirmed many, many times. The explanation for it may or may not be WIMPs.

I'll propose a toast: to experimental physicists everywhere, and to the curiosity and imagination that moves them. May they have extraordinary good insight and good luck in unraveling this very interesting mystery.
Infinite Fractal Consciousness
5 / 5 (8) Aug 09, 2012
I just wanted to clarify, because the article's title is ambiguous, and seems to be easily misunderstood: in regards to the findings, "near the Sun" means "in our neighborhood, which includes thousands of orange K dwarf stars. "Near the Sun" was not meant to be read as "interior to the orbit of Mercury."
DarkHorse66
3.7 / 5 (9) Aug 09, 2012
IMO the rational core of your hypothesis is in fact, some materialization of dark matter was observed around core of Milky Way galaxy in form of 512 keV positron signal.

Somehow, I don't think that the positron qualifies as a dark matter candidate. http://en.wikiped...Positron
The level of detectability for an antiparticle is the same as for its 'standard' counterpart. Ergo, if we can detect and identify one, we can detect and identify the other.
Regards, DH66
antialias_physorg
4 / 5 (8) Aug 10, 2012
iscussed almost nothing about their "detection methodology". All mass has gravity & I was expecting a discussion somewhere in the body of the discussion that they had discovered that gravity in the region of our Sun has now measured to be much higher than originally thought.

Just read the paper linked at the bottom of the article. Their method is explained therein.

is dark matter a semantic identifier of phenomena not yet explained, or is it something specific that is explained but we just cannot 'see' yet.

It's something which we haven't nailed down but of which we already know some properties. It's still fuzzy but not totally so.
Satene
1 / 5 (7) Aug 10, 2012
are eager to jump from "measurement anomaly" to "invisible, weakly-interacting but massive particles."
IMO dark matter is both. It's formed with gradient of gravitational waves concentration, which manifest pretty well like the shadows between galaxies (dark matter fibbers connecting them), but at the moment, when its density will exceeds certain limit, it will condense into neutrinos in similar way like the Brownian noise at the water surface condenses into tiny turbulent vortices. But because physicists can handle only one formal model in single moment (because of the complexity of resulting solution and various psychosocial reasons, like the jealousy), they cannot get them working all. IMO if we would model the continuous gradient of space-time fluctuations in hyperdimensional environment, it would appear like discontinuity condensing into particles, if we would observe it from low-dimensional space-time perspective - it doesn't differ conceptually from condensation of gas.
Satene
1.4 / 5 (11) Aug 10, 2012
The dark matter is bonanza for theorists. During time the physicists proposed dozens of theoretical models, which could be ordered by the rest mass of particle considered into line

...scalar field, quintessence, mirror matter, axions, dilatons, inflatons, heavy photons, fat strings, sterile neutrinos, chameleon particles, dark fluid and dark baryons, fotinos, gravitinos and WIMPs, SIMPs, MACHOs, RAMBOs, DAEMONs and micro-black holes... ..and I probably missed many others.

The physicists prefer particle models for psychosocial reasons: if you invent and propose some new particle, it could be named after you at the moment, when it will get confirmed and you can get grants for construction of its detectors, which will attract another people and money and business into corresponding area. So that new particles are popping in physical theories spontaneously in similar way, like the neutrinos from dark matter.
Benni
1.6 / 5 (7) Aug 10, 2012

No dark matter was found. Only the gravitational anomalies.


The article mentioned nothing about gravitational anomalies, that was the disappointing part of this whole thing. All it discussed was that "density" was found to be twice what was expected. The word "twice" is a strictly relative wording, "twice" from what? If you can't even bottle up a liter of dark matter how do you measure the density of it? The only other way is to calculate the expected gravity field of the observable masses & subtract that from the total gravity that is measured which we can do, that will quantify the total amount of dark matter present.

It is frustratingly odd to me that no effort was made to to explain how they arrived at their declaration of "twice" the "density".
antialias_physorg
3.7 / 5 (6) Aug 10, 2012
The word "twice" is a strictly relative wording, "twice" from what?

It's stated quite plainly inthe article:
Jan Oort in the Netherlands discovered that the density of matter near the Sun was nearly twice what could be explained by the presence of stars and gas alone.


It's pretty simple: There is (ordinary) matter there. But the effect observed is of a magnitude that would require twice as much matter to be there.
mpc755
Aug 10, 2012
This comment has been removed by a moderator.
mpc755
1 / 5 (8) Aug 10, 2012
Non-baryonic dark matter has recently been shown not to be anchored to matter.

Q. What is the difference between non-baryonic dark matter which is not anchored to matter and aether?
A. Nothing.

Aether has mass and physically occupies three dimensional space. Matter moves through and displaces the aether.
antialias_physorg
3.5 / 5 (8) Aug 10, 2012
What is the difference between non-baryonic dark matter which is not anchored to matter and aether?

Another sockpuppet? Got banned again, did we?
Don't you ever get tired of this charade?
Benni
1 / 5 (8) Aug 10, 2012
The word "twice" is a strictly relative wording, "twice" from what?

It's stated quite plainly inthe article:
Jan Oort in the Netherlands discovered that the density of matter near the Sun was nearly twice what could be explained by the presence of stars and gas alone.


It's pretty simple: There is (ordinary) matter there. But the effect observed is of a magnitude that would require twice as much matter to be there.


You're not getting it!!!! HOW DID HE Do IT? Am I clear?????
antialias_physorg
3.9 / 5 (7) Aug 10, 2012
And you're not getting it: The link to the paper is right there at the bottom of the article. They explain quite plainly how they did it.

Am I clear?
Bottom.
Article.
Link.
Click.
Read.
Turn off caps lock.
packrat
1 / 5 (5) Aug 10, 2012
This is a bit off the wall but since photons don't have rest mass but do have the effects caused by their momentum, couldn't those be causing the effects that we think is dark matter? Get enough photons together and they do have mass effects and if it has that effect you get gravity or something akin to it or possibly plasma type responses.
That would indicate that the brighter a galaxy or whatever is the more gravity it would seem to have. In that case you could also get gravity effects from the space between galaxies too as there would still be photons flowing through it.
That makes more sense to me than theoretical particles that may or may not exist causing the effects.
mpc755
1 / 5 (3) Aug 10, 2012
Another sockpuppet? Got banned again, did we?
Don't you ever get tired of this charade?


"Relativity actually says nothing about the existence or nonexistence of matter pervading the universe, only that any such matter must have relativistic symmetry. [..] It turns out that such matter exists. About the time relativity was becoming accepted, studies of radioactivity began showing that the empty vacuum of space had spectroscopic structure similar to that of ordinary quantum solids and fluids. Subsequent studies with large particle accelerators have now led us to understand that space is more like a piece of window glass than ideal Newtonian emptiness. It is filled with 'stuff' that is normally transparent but can be made visible by hitting it sufficiently hard to knock out a part. The modern concept of the vacuum of space, confirmed every day by experiment, is a relativistic ether. But we do not call it this because it is taboo." - Robert B. Laughlin, Nobel Laureate in Physics
rubberman
1 / 5 (5) Aug 10, 2012
@Packrat: A few months ago in another string regarding the effects/properties of DM Benni proposed an explanation for DM that I simplified to something similar to what you just said. (Because I am not a physicist). Except my off the wall theory had photons retaining mass once their visible energy had been exhausted, just not enough for us to be able to detect. I liked it because it fit the current parameters for the observed effects of DM along with the locations of said effects. Always near galaxies and permeating them, but not observed in inter galactic space, so clearly related to normal matter, possibly even produced by it. The fact that it's only identifiable property (for us) is gravity, and that it makes up such a high percentage of mass for the universe would indicate a uniform source for production, yet restricted to galactic proximity....

Sooo weak though....
gulfcoastfella
1 / 5 (1) Aug 10, 2012
reminds me of the square root of -1

Sometimes you just need something impossible to make the formulas work.


The title "imaginary" is an unfortunate artifact from history. "Imaginary" numbers are just as real as the "real" numbers.
ValeriaT
1 / 5 (3) Aug 10, 2012
MrVibrating
1 / 5 (2) Aug 10, 2012
The article title threw me slightly - at first i read "near the sun" as "between us and the sun"... should've just said "in our galactic neighborhood"... but fascinating result all the same - IIRC another recent article on PhysOrg reported research claiming the exact opposite conclusion - must've been what, six weeks ago?

Certainly makes for a lively debate eh...
Benni
1 / 5 (4) Aug 10, 2012
OK Ant Phy....finally I broke down & went to the paper itself. Section 5 is a really good synopsis of the entire methodology, that way you don't need to wade through all the calculus to figure out exactly how they're doing this.

Sooooo.....MrVibrating.....the article as presented on this site threw me more than just "slightly", they are talking about a whole neighborhood of stars here, not isolating it to just our Sun just as you said. It was the only way they could come up with enough gravity & mass to perform their methodology. Now, it does leave me to wondering if they properly accounted for the gravity that is carried by the energy fields around these stars, if they didn't, then it could be as much as 75% of the way back to square one.

MrVibrating
2 / 5 (4) Aug 10, 2012
Hmm not sure if that would add up - the energy field around a star - let's say the area enclosed by its heliosphere - is indeed subject to mass equivalency, however it is just that; relativistic mass, aka radiation pressure. In other words it's not 'massive' itself (obviously photons are massless), and only becomes so equivalent when interacting with baryonic matter, ie. being absorbed or re-emitted. It's in another field, the EM field, whereas the mass being inferred is real and stationary..

Or perhaps you refer to the star's ion atmosphere, constituting its 'stellar wind' - however this mass is comparatively very small, and, like radiation pressure, vectored away from the star, thus forming a repulsive, not attractive, interstellar force.. Not sure this would help explain anomalous gravitation..
mpc755
Aug 10, 2012
This comment has been removed by a moderator.
mpc755
1 / 5 (6) Aug 10, 2012
- Robert B. Laughlin, Nobel Laureate in Physics


Someone just rated a quote from a Nobel Laureate a 1/5.

Gotta love the ignorance.
Benni
1 / 5 (5) Aug 10, 2012
@ MrVibrating......Actually my point being that all energy fields have as you say, "mass equivalency", or some would say "equivalent rest mass".

Photons all have gravity because they are not massless, but the problem we encounter with electro-magnetic fields is accurately detecting them at "lowest level of detection" or "highest level of detection", we simply don't have the means to measure energy above or below those two points on the EM Spectrum, above & below those two points is where "dark energy" lies & in a nutshell is believed to be where most of the gravity in the Universe is posited.

And herein lies the crux of my question as to whether their analyses is accounting for a big chunk of the universe that can't be graphed on the electro-magnetic spectrum because, it is beyond the capability of present day spectroscopy to detect & then measure those fields.

Part of my job as an energy engineering specialist deals with spectroscopy, and every system deals with HLD & LLD.
Q-Star
1.7 / 5 (6) Aug 10, 2012
@Benni says: "And herein lies the crux of my question as to whether their analyses is accounting for a big chunk of the universe that can't be graphed on the electro-magnetic spectrum because, it is beyond the capability of present day spectroscopy to detect & then measure those fields."

When it comes to the question of Dark Energy, I think you are getting right to crux of the problem, I've always pictured it as energy no different than the EM radiation we already understand so well, we just haven't built the detector sensitive enough yet,, we'll probably find (when technology catches up) that we understood it all along,,,,

Dark matter? I'm still in the WIMP camp on that one.
ValeriaT
1 / 5 (5) Aug 11, 2012
IMO the subtle, but significant indicia of potential problems with WIMPs is, nobody actually understands, why this particles should exist at all. I mean at fundamental logical level: everyone understands, that for example electrons are good to exist, because they could explain the quantized transport of charge, composition of atoms and discharges in gases, etc... It all boils down to the misunderstanding (or rather complete lack of understanding) of the SUSY model at the intuitive level...

Another question is, what the WIMPs are actually good for? For making grants, publications and money with building of detectors? OK, but without it we don't need these WIMPs for anything serious. Can the WIMP do something, which for example atom nuclei or energetic neutrinos cannot do? In another words, physicists are trying to explain something which they don't really need with something, which they don't really understand. It's deadly combination for every robust theory.
Benni
1 / 5 (6) Aug 11, 2012
When it comes to the question of Dark Energy, I think you are getting right to crux of the problem, I've always pictured it as energy no different than the EM radiation we already understand so well, we just haven't built the detector sensitive enough yet,, we'll probably find (when technology catches up) that we understood it all along,,,,


"Dark Energy" is simply a lot of electro-magnetic radiation on the EM spectrum for which we have no means to measure using the present technology of spectroscopy. Our field engineers are mostly concerned with gamma & x-ray emissions from our hi-voltage equipment, gamma ray being the highest frequency we can detect, we are concerned with radio influence voltages (RIV) at longer wavelengths but they are less penetrating than gamma EM.

We can computer model the EM spectrum to span a distance of 1500 miles & the visible light portion will only span a few inches of that length & this is only what we have instrumentation to measure........

Benni
1 / 5 (4) Aug 11, 2012
.......now there is the remaining portion at the shortest wavelength end & at the longest wavelength end, above & below which we know energy exists but are unable to measure, we have simply created an artificial range of frequencies we can measure because that is what is presently most useful.

The true EM Spectrum in all likelihood spans the diameter of the Universe, that is there are photons of such low frequency they oscillate just one time as they travel through the cosmos, we will never be able to build instrumentation to detect such low frequency EM (photons). Then there is the opposite high frequency end of the spectrum where photons oscillate in such short wavelength we will never be able to measure that either.

The question becomes: How much energy exists beyond the highest & lowest ends of the EM? Gravity measurements indicate "most" of the total of all energy exists there, & that is where the unexplained total of gravity exists, we call this EM "dark energy".
Benni
1 / 5 (4) Aug 11, 2012
If the team involved in this calculation did not extract the contribution of the gravity field of "dark energy" from their calculations, that is why their revised estimation of "dark matter" in our galactic region will be way off. I've only briefly skimmed the paper so I don't know, maybe I'll get more ambitious during the weekend & wade through all their math.
MrVibrating
2.6 / 5 (5) Aug 11, 2012
Photons are by definition massless, propagating at lightspeed. Virtual photons can, notionally, exist at all possible wavelengths up to the breadth of the universe, but real photons are limited in size by certain practicalities - photons are caused by oscillating charges, with a wavelength corresponding to the distance involved, however charges DO have mass so this places one constraint on their size, furthermore the longest such wavelength we could measure would be limited by the distance they're emitted vs the rate of the universe's accelerating expansion; this causes a 'horizon' of infinite redshift beyond which such photons will never reach us. Because energy is a function of frequency, such long wavelengths would have proportionately tiny relativistic masses, but which again, would subtract from, not add to, the rest mass of the source.

At the opposite extreme, the shortest wavelength possible is set at twice the Planck length; you can't 'write' anything smaller onto spacetime.
MrVibrating
1 / 5 (2) Aug 11, 2012
..and dark energy is thought to have an homogeneous distribution throughout the cosmos, therefore any hypothetical mass associated with the field does not add to the mass of any locale relative to the bulk. Besides, like radiation pressure, dark energy is a repulsive, not attractive, effect, so doesn't seem to help in explaining anomalous gravitation.

gopher65
5 / 5 (5) Aug 11, 2012
There are really 2 possibilities to reconcile the data. Dark matter or MTOG (modified theory of gravity).

This is no longer the case. The data as of ~2 years ago has ruled out an explanation based on modifying the gravity of visible objects and gas (this includes black holes and brown dwarfs, even though they're not really visible, as such). At least, it can't be the *sole* cause of dark matter observations.

The reason for this is the various observations of "clouds" of dark matter that are removed from either galaxies or gas clouds, but can still be detected via their gravity. Modeling of these clouds suggests that they were tossed out of galaxies during collisions. It is fundamentally not possible to explain these particular observations with a MTOG.
Benni
1 / 5 (5) Aug 11, 2012
@ MyVibrating - What physics book & author did you study to make a statement this: "photons are by definition massless"? If you believe that, then explain the source of gravity carried by energy fields(photons). Photons are simply transformed mass moving at 186,284 miles/sec. Gravity does not simply disappear from the Universe because some amount of mass is converted to energy. Photons do not have "rest mass" because they cannot exist "at rest", but they have "rest mass equivalence" and thus a gravity component.

My whole point from my above posts being we do not know what the flux densities of unmeasurable photon frequencies are so as to be able to accurately assign the strength of their gravitational fields fields.

MrVibrating
3 / 5 (6) Aug 11, 2012
Anything with finite energy that propagates at C is by definition massless.

Relativistic mass, or radiation pressure, only comes into effect when photons interact with matter.

Consider the case of a star: its density is a function of both compression due to mass & gravity, vs expansion due to its (considerable) internal radiation pressure. Stars collapse when their fuel's exhausted because this radiation pressure drops. Radiation pressure is an outward force, away from the star, not an inward force towards it.

Furthermore it subtracts from the system's rest mass, not adding to it. Consider particle collision products where mass decrease is proportional to the energy emitted...
Benni
1 / 5 (4) Aug 11, 2012
Anything with finite energy that propagates at C is by definition massless.........

........Furthermore it subtracts from the system's rest mass, not adding to it. Consider particle collision products where mass decrease is proportional to the energy emitted...


You're contradicting yourself here, you are wrong in the first instance, correct in the second. But I still not sure you understand that a proportional amount of gravity is also carried off by the energy that is emitted....call it "conservation of gravity" if you please, and it is all this gravity that is measured in excess supply throughout the Universe that has contributed to the concept of "dark energy" and to a lesser degree that of "dark matter". Time to move on I guess.....
sherriffwoody
not rated yet Aug 11, 2012
Wouldn't this dark matter have effected the results of Einsteins prediction of light curvature around the sun? Or does light not get effected by dark matter, or was dark matter accounted for in the equation? I apologise in advance for my ignorance.
Q-Star
2.2 / 5 (5) Aug 11, 2012
Wouldn't this dark matter have effected the results of Einsteins prediction of light curvature around the sun? Or does light not get effected by dark matter, or was dark matter accounted for in the equation? I apologise in advance for my ignorance.


Apology not necessary. It's Einstein's relatively that first led to the realization of something like Dark Matter. He predicted the conditions under which it has manifested itself. The Dark Matter most assuredly effects light,,, google up "gravitational lensing" and you'll find plenty of background information. It's become a very useful tool in astrophysics in general and cosmology in particular.
sherriffwoody
not rated yet Aug 11, 2012
Yes but was the test of his prediction which proofed Einstein correct in 1918? Inclusive of dark matter? Did they know about it then, wouldn't the result have been different if dark matter wasn't accounted for in theory but does exist? Surely the spread of dark matter would change the distribution of the mass and therefore the amount of the lensing effect during this experiment?
Q-Star
2.6 / 5 (5) Aug 11, 2012
Surely the spread of dark matter would change the distribution of the mass and therefore the amount of the lensing effect during this experiment?


It would have been such a small amount that it would not, and is not presently measurable. We are just to close to the sun. But the exact same conditions exist which we do see and measure because the intervening distances are greater, so the effect is more pronounced. That's why the study in the article included space out to several hundred parsecs. We are just a miniscule distance from the Sun therefore dark matter would have little effect from here to there (immeasurably little with today's instruments).

Einstein predicted gravitational lensing, all dark matter theory is based on it. The discovery of dark matter is a direct result of his work.
ValeriaT
1 / 5 (3) Aug 11, 2012
Einstein predicted gravitational lensing, all dark matter theory is based on it. The discovery of dark matter is a direct result of his work.
It's not so simple. The dark matter was originally found with violation of Newtonian gravity (Zwicky, 1933), on which general relativity is based too. This finding was therefore independent of Einsteinian relativity. Currently one of methods of dark matter detection is based on violation of gravitational lensing predicted with general relativity. It's true, the total amount of dark matter is backward determined with using of Einstein's relativity, because we have no better way, how to define it - but this is just the portion of lensing, which cannot be derived from general relativity easily and which therefore violates the equivalence principle in this way. I don't know, if Einstein was happy from dark matter finding, but what we know reliably is, the finding of Zwicky was ignored with mainstream physics for sixty years.
Q-Star
2.7 / 5 (6) Aug 11, 2012
"based on violation of gravitational lensing predicted with general relativity"

Predicted using only visible matter, it was relativity that says something else must be there that you are not seeing, hence the "relativity" says there must be something there which is not normal matter. Zwicky knew that, he said as much, that IF relativity is correct, then there is more there than we can see.

That is why I said Einstein's relativity theory predicts it. Dark matter is the only way it remains verified. If there were no dark matter than Einstein's relativity would not account for the observations.
ValeriaT
1 / 5 (2) Aug 11, 2012
Zwicky knew that, he said as much, that IF relativity is correct, then there is more there than we can see
Technically, it was Jan Oort, who observed the violation of rotational curves of stars inside of Milky Way, Zwicky estimated the mass of galaxies with their luminosity and found again, that the stars couldn't keep their tracks, because the mass found was too low. Both findings therefore were independent of general relativity, the Newtonian gravity was enough for their detection. You should realize, that relativistic effects were too weak for being observed in distant galaxies with technology of that time. From this reason Zwicky probably didn't bothered about general relativity at all. Do you have some link supporting the sentence "he said as much, that IF relativity is correct, then there is more there than we can see"?
That is why I said Einstein's relativity theory predicts it.
This is ufortunately quite wrong by now - we have no working theory of DM based on GR.
Q-Star
2 / 5 (4) Aug 11, 2012
@ ValeriaT "In 1937 Zwicky thought of another way to investigate dark matter. If by chance a massive galaxy lies along our line of sight to a more distant galaxy, it could act as a gravitational lens, warping the surrounding space to magnify, distort, and even multiply the image of the background galaxy. This was a direct application of Einsteins Theory of General Relativity."

Ask and you shall receive, one source of many. The article which contains the above quote. http://www.amnh.o...cky.html
Q-Star
2.3 / 5 (6) Aug 11, 2012
"This is ufortunately quite wrong by now - we have no working theory of DM based on GR."

I'm not sure who "we" are. But the world of astrophysics has. If there is no DM, then GR won't work. If there is no DM then GR is just so much rubbish. DM makes GR work, hence the GR predicts DM.
ValeriaT
1 / 5 (3) Aug 11, 2012
@ ValeriaT ".. This was a direct application of Einsteins Theory of General Relativity."
I see, thank you for link. Now I do understand the source of your confusion. Well, Zwicky didn't use this method at the end, but it's actually used by now for weighing of dark matter together with inertial mass. The mass of dark matter is determined with subtraction of inertial mass determined with some independent method. The fact, the amount of dark matter observed in our universe perfectly fits the GR is very simple: GR was used for its calculation from gravitational lensing observed. But Einsteinian relativity has nothing very much to say about theoretical amount of dark matter in its present state.
If there is no DM, then GR won't work
It would work way more simpler, if the DM wouldn't here. I do believe, that DM can be estimated with consideration of GR in extradimensions, but until we do it, then the DM poses rather problem (and occupation) for relativists.
mpc755
Aug 11, 2012
This comment has been removed by a moderator.
Q-Star
2 / 5 (4) Aug 11, 2012
Hey, it's okay about my confusion, I'm a Cal Tech alum, discussing all things Zwicky is a cottage industry for us. We are, to a person, embarrassed that he never received a Nobel. My parents paid handsomely to get me so confused, I'm glad you think they got their money's worth.
ValeriaT
1 / 5 (2) Aug 11, 2012
IMO the misunderstanding of yours is nothing exceptional, because mainstream physicists are doing it routinely too. For example, here we can read, how the physicists confirmed the general relativity with measuring of dark matter calculated with using of general relativity. This is indeed a circular reasoning in its rather transparent state. The complexity of math involved prohibited the physicists to see it clearly, but this is what the contemporary physics is often about.
unknownorgin
1 / 5 (3) Aug 11, 2012
It is well known that time slows down in a gravitational field so it is a reasonable idea that where time is passing slower in relation to the event horizon gravity would increase. This would mean that the gravitational field of an object is not directly proportional to its mass but a product of its mass, in otherwords multiply instead of add when calulating the strength of gravity.
ValeriaT
2.3 / 5 (3) Aug 11, 2012
where time is passing slower in relation to the event horizon gravity would increase
I'm afraid, I didn't understand this sentence correctly, which may be of course the result of my poor knowledge of English grammar. Could you elaborate/reformulate it, plz?
ValeriaT
1 / 5 (3) Aug 11, 2012
IMO dilatation of time would lead into slower motion of object falling into black hole from the perspective of observer, who is observing its fall from outside. It could lead into his impression, that the gravity is rather lower, than higher there. This paradox is discussed with prof. Susskind for example here in context of black hole complementarity. The common understanding is, both falling object, both observer would perceive the same event differently.
Q-Star
2.6 / 5 (5) Aug 11, 2012
@ ValeriaT

You should read your own link more carefully. It seems to be saying exactly what I have tried to point out.

So contemporary physicists are getting it all wrong? That's unfortunate, to bad Aristotle and Ptolemy aren't still around to straighten us out.

Physics IS dependent on mathematics.

But mathematicians have a much easier field to play upon than physicists do. Physicists must deal with the real world with all the changes, dynamics and multitudinous interactions of the universe and the varying degree in difficulty of making observations,,,,,,,, Mathematicians only have to deal with perfect conditions in an ideal environment. In math, YES NO AND & OR is about the only things which you have to consider.

If I am confused, I am in very good company. So what is your claim to fame? Point me to some of your work. Oh, the mainstream have probably conspired to keep it unpublished. But then there is the internet.
ValeriaT
1 / 5 (3) Aug 11, 2012
So contemporary physicists are getting it all wrong?
I just said, you shouldn't use the general relativity for estimation of dark matter mass with Zwicky's method, if you want to check the general relativity with the result. If you still would do it, you should indeed always find, that the dark matter amount observed corresponds the general relativity exactly, isn't it true?

Look, one half of physicists is doing money with confirmation of relativity with dark matter observation, whereas the second half of physicists is doing money with development various methods (MOND, TeVeS, MOG/STVG,..), how to fit the general relativity to dark matter observations. Does it looks like consistent activity for you?
Q-Star
3.1 / 5 (7) Aug 11, 2012
"Does it looks like consistent activity for you?"

It's the only way science works. All viable theories have to be pursued. If all the physicists were all working on the same theory then everything would become stalled at a dead end. There have always been competing theories in any field of learning. That is why all scientific theories must be falsifiable.

One guy gets it right, another got it wrong, no one guy gets it right every time. Galileo, Kepler, Newton, everyone in-between to Einstein, Hubble, Lemaitre, Zwicky, Feynman, all of them got just as many things wrong as they got right. Everyone of them had some real doozies, as we look back on them.

It's only the things you got right that make you a star. Get something really big right, you become a really big star. But they were still wrong about as many things as they were right about. That's always been the case, and always will be the case.

You must pursue every viable theory before you can find the TRUTH.
ValeriaT
1 / 5 (3) Aug 11, 2012
All viable theories have to be pursued .. You must pursue every viable theory before you can find the TRUTH.
The problem is in definition of "viability". But we aren't talking about viability of alternative theories here, but about (rather trivial) logical flaw, based on circular reasoning. Such an approach will always remain nonviable. I'm just talking about it here not for glory or propagation of my theories, but in an effort not to propagate the same misunderstanding further. You can learn from it in your further carrier. The usage of circular reasoning in mainstream physics is way more frequent, than you may think and with growing complexity of mathematical methods used the risk of less or more hidden feedback increases gradually.
Lurker2358
1.6 / 5 (7) Aug 11, 2012
Good lord. Statistics 101. Talk about not knowing what you don't know.


You can't make statistics for unknown unknowns because you don't even know they are unknowns.

Even if "Dark Matter" exists, it could be composed of 2 or more unrelated issues: new particles, faulty formulas, missing variables, etc.

You can't really make statistics for something that hasn't even been defined yet...

Nobody even knows whether Dark Matter is a "something," a physical matter or energy, or whether it's just a formula error, or some combination of the two, or something totally unexpected.
kaasinees
1 / 5 (4) Aug 11, 2012
they are clearly talking about the bucky balls they found near the sun.
Q-Star
2.3 / 5 (6) Aug 11, 2012
Tin foil hats will make you easier to spot in the sun but they won't help get the girls.
rah
1.5 / 5 (8) Aug 11, 2012
This article is total nonsense. It may be a comedy piece.
mpc755
Aug 11, 2012
This comment has been removed by a moderator.
rah
1 / 5 (6) Aug 12, 2012
This stuff is better than The Onion news articles.
MrVibrating
2.3 / 5 (3) Aug 12, 2012
Anything with finite energy that propagates at C is by definition massless.........

........Furthermore it subtracts from the system's rest mass, not adding to it. Consider particle collision products where mass decrease is proportional to the energy emitted...


You're contradicting yourself here, you are wrong in the first instance, correct in the second. But I still not sure you understand that a proportional amount of gravity is also carried off by the energy that is emitted....call it "conservation of gravity" if you please, and it is all this gravity that is measured in excess supply throughout the Universe that has contributed to the concept of "dark energy" and to a lesser degree that of "dark matter". Time to move on I guess.....

A massive entity (ie. something with mass) needs infinite energy to reach C. Ergo, photons are massless. They do not "carry away gravity" such that there is a gravity associated with the photon atmosphere around a star.
MrVibrating
1 / 5 (2) Aug 12, 2012
Matter moves through and displaces the aether.

Aether has mass.

Displaced aether pushing back toward matter is gravity.

Interesting view, so how do you explain the Michelson Morley result - surely you're invoking such a speed difference, so how to measure it?
Lurker2358
2.4 / 5 (7) Aug 12, 2012
A massive entity (ie. something with mass) needs infinite energy to reach C. Ergo, photons are massless. They do not "carry away gravity" such that there is a gravity associated with the photon atmosphere around a star.


Ironically, the very fact that photons have energy means that they actually DO carry away mass from stars.

This is yet another paradox in physics, because photons most certainly have energy, AND they are most certainly effected by the GRAVITY of stars, planets, and black holes, and all other matter.

Photons also have MOMENTUM, which is why a solar sail can work, in theory.
ValeriaT
1 / 5 (5) Aug 12, 2012
This apparent paradox of mainstream physics can be solved easily with assumption, that photons are moving more slowly than the (pure harmonic) light (wave), being a solitons at the water surface. They just disappear and re-apper somewhere else due the quantum decoherence in similar way, like the real solitons at the water surface. After all, the relativity has nothing to say about (speed of) photons, because photons are quantum phenomena and the relativity doesn't support quantization. We actually never observed the spreading of single photon along whole path, we always measured the speed of mixture of photons.
gopher65
5 / 5 (2) Aug 12, 2012
Photons also have MOMENTUM, which is why a solar sail can work, in theory.

In theory? Since NASA currently has a solar sail operating in space, I'd say it's more than "in theory".
ValeriaT
1 / 5 (2) Aug 12, 2012
Solar sails work with pressure of solar wind (protons) preferably. The pressure of photons corresponding solar constant p = 1328 / 300 000 000 = 4,43x10-6 Newtons per square meter, i.e. way too low for being used in feasible way.
MrVibrating
3.4 / 5 (5) Aug 12, 2012
A massive entity (ie. something with mass) needs infinite energy to reach C. Ergo, photons are massless. They do not "carry away gravity" such that there is a gravity associated with the photon atmosphere around a star.


Ironically, the very fact that photons have energy means that they actually DO carry away mass from stars.

This is yet another paradox in physics, because photons most certainly have energy, AND they are most certainly effected by the GRAVITY of stars, planets, and black holes, and all other matter.

Photons also have MOMENTUM, which is why a solar sail can work, in theory.

Yes but mass and energy are covariant; it's one or the other, not both. Benni's contention is essentially that the EM atmosphere around a star constitutes a gravitating mass, as an explanation for the DM problem. As i've tried to explain, relativistic mass only comes into effect when photons interact with fermions; That is, the momentum to which you refer is radiation pressure!
MrVibrating
1 / 5 (2) Aug 12, 2012
..also, isn't solar sailing more geared to capturing the ion wind? The other example that comes to mind is the Crookes radiometer, although this too is now known to use ionic pressure.

Edit: oops, or just what ValeriaT said..
MrVibrating
1 / 5 (2) Aug 12, 2012
This apparent paradox of mainstream physics can be solved easily with assumption, that photons are moving more slowly than the (pure harmonic) light (wave), being a solitons at the water surface. They just disappear and re-apper somewhere else due the quantum decoherence in similar way, like the real solitons at the water surface. After all, the relativity has nothing to say about (speed of) photons, because photons are quantum phenomena and the relativity doesn't support quantization. We actually never observed the spreading of single photon along whole path, we always measured the speed of mixture of photons.
Interesting interpretation, but presumably then you agree that EM radiation doesn't cause gravitation..?
ValeriaT
1 / 5 (3) Aug 12, 2012
I don't (agree) - it's the necessary consequence of this model. As we know from scattering observations in vacuum the mutual cross-section of photon-photon interaction is very low, but it's not completely zero.
For example, one of unsolved problems of physics are remote gamma ray bursts, which can travel across whole universe without apparent attenuation. During explosions of supernovas the energy corresponding the mass of Sun can be released in a brief moment of time. The natural explanation could be, that the dense cluster of gamma ray photons formed is moving as a single body being held together with own gravity and it may travel across universe like swarms of photons, which not only doesn't scatter, but it can even collect another photons from outside, which travel in the same direction.
indio007
1 / 5 (5) Aug 12, 2012
Anything to preserve Einstein and his "thought experiments".....
mgmirkin
1 / 5 (4) Aug 12, 2012
So, did they miss this story when they were issuing their prediction about tons of dark matter near sun / solar system:

http://www.nature...-1.10494

Prediction: FAIL in light of actual observations?
mgmirkin
1 / 5 (4) Aug 12, 2012
Did they miss this story before issuing their predictive proclamation?

(Survey finds no hint of dark matter near Solar System)
http://www.nature...-1.10494

Apparently we're NOT swimming in a Dark Matter sea in this neighborhood... Prediction FAIL in the harsh light of actual observation?

Ohh, and the 225 day results are in for Xenon100:

(First 10 days; no viable candidates)
http://arxiv.org/abs/1005.0380

(100 days; no viable candidates)
http://arxiv.org/abs/1104.2549

(225 days; no viable candidates)
http://arxiv.org/abs/1207.5988
StarGazer2011
1 / 5 (6) Aug 12, 2012
Hold on ...

We used simulations (which assume a given theory/model) and then altered the observation technique until it gave us the answer we wanted?
Thats called begging the question, and its not just unscientific, its anti-science!
These guys should go into climate science, they would find a natural home there.
Benni
1 / 5 (3) Aug 12, 2012
@ MyVibrating

Give it up guy.....take a Physics 102 course someplace, pass it, get a final grade & maybe by then you'll understand what is meant by the terms "rest mass" & "rest mass equivalence". I've attempted to explain to you it is a measurable scientific fact demonstrable by voluminous amounts of data that photons carry an inherent gravity field, and just like other interstellar bodies the more photons that cluster together (flux density) the greater will be the inherent force of gravity from that concentration of photons.

On the other hand I have an idea that will spare you the pain of first needing to take a couple courses of Calculus before you get to Physics 102......type "rest mass equivalence" into a search engine & go read about it.....
MrVibrating
1 / 5 (2) Aug 13, 2012
@ValeriaT - you're suggesting photon-photon elastic scattering indicates non-zero photon mass and thus mutual gravitation?

PPES depends on an interaction with massive virtual particle pairs - the net mass of such a system remains zero as the pair mutually self-annihilate. The gravity of any such light is likewise exactly equal to that of the vacuum: zero. As far as modern physics has been able to discern, light does not gravitate.

Gamma rays may be emitted by dark matter, but they're not dark matter themselves - and even if they did have mass, there's simply nowhere near enough of them to make up the shortfall... and besides, if there were then we wouldn't be here to notice anyway...

The notion that DM is any form of EM radiation is a contradiction in terms. Whatever it is must be baryonic matter, made up of fermions... that, or a modification of gravity / new force etc.
MrVibrating
1 / 5 (2) Aug 13, 2012
@ MyVibrating

Give it up guy.....take a Physics 102 course someplace, pass it, get a final grade & maybe by then you'll understand what is meant by the terms "rest mass" & "rest mass equivalence". I've attempted to explain to you it is a measurable scientific fact demonstrable by voluminous amounts of data that photons carry an inherent gravity field, and just like other interstellar bodies the more photons that cluster together (flux density) the greater will be the inherent force of gravity from that concentration of photons.

On the other hand I have an idea that will spare you the pain of first needing to take a couple courses of Calculus before you get to Physics 102......type "rest mass equivalence" into a search engine & go read about it.....
Lol yes i do apologise for my ignorance, but i tried your term "rest mass equivalence" in a famous search engine and the first hit was your mention of it above...

Stupid, ignorant search engines eh...
MrVibrating
1 / 5 (3) Aug 13, 2012
Q-Star
3.3 / 5 (11) Aug 13, 2012
For any one who might stumble across this site through a search engine, or story link. Particularly if you don't have a science background.

WARNING: Be sure to check some legitimate sources for clarification. If you're not a scientist, wiki would be a good place to start.

1) Some of the stuff you'll see here is politely called "fringe science". It MAY be worth pursuing.

2) Some of the stuff you'll see in these comments are "pseudo-science", They are rambling from people who don't know. They may fling about science sounding jargon, but they don't know what the words mean.

3) And some of the stuff you'll see in these comments are from failed science fiction writers who try to pass themselves off as someone who knows science.

Choose what you read in these comments wisely. If you don't you will, at best, make a fool of yourself on a forum like this. At worse, you might make a fool of yourself in the real world if you run into someone who does actually know science.
eric96
1.8 / 5 (5) Aug 14, 2012
Ha you suckers, give me a 1/5 rating yet I am right:

http://news.softp...48.shtml

http://scienceblo...nt-32639
mpc233
1 / 5 (6) Aug 14, 2012
Matter moves through and displaces the aether.

Aether has mass.

Displaced aether pushing back toward matter is gravity.

Interesting view, so how do you explain the Michelson Morley result - surely you're invoking such a speed difference, so how to measure it?


The Michelson Morley experiment looked for a stationary aether the Earth moved through.

The aether is, or behaves similar to, a supersolid.

The aether connected to and neighboring the Earth is displaced by the Earth.

The state of the aether connected to and neighboring the Earth is the same, or almost the same, through out the Earth's rotation about its axis and orbit of the Sun.
Martin_Shaw
1 / 5 (1) Aug 15, 2012
Reminds me of the quest for ether and the MichelsonMorley experiments
MrVibrating
1 / 5 (2) Aug 15, 2012
Matter moves through and displaces the aether.

Aether has mass.

Displaced aether pushing back toward matter is gravity.

Interesting view, so how do you explain the Michelson Morley result - surely you're invoking such a speed difference, so how to measure it?


The Michelson Morley experiment looked for a stationary aether the Earth moved through.

The aether is, or behaves similar to, a supersolid.

The aether connected to and neighboring the Earth is displaced by the Earth.

The state of the aether connected to and neighboring the Earth is the same, or almost the same, through out the Earth's rotation about its axis and orbit of the Sun.

interesting, answer, thanks...
elektron
1 / 5 (2) Aug 15, 2012


... If we don't know what we don't know, then what in the world does 99% confidence mean?



Everybody knows what they don't know. You merely have to name it. If I ask you 'do you know swahili', you are not going to say, 'I don't know if I know swahili'.
tkjtkj
not rated yet Aug 16, 2012
Parsec :
"However, I also disagree 'antialias_physorg' in at least one point. There are really 2 possibilities to reconcile the data. Dark matter or MTOG (modified theory of gravity). They are quite different. Dark matter simply posits some particle, MTOG posits modification in Einstein's theory of relativity and the actual property of spacetime. This are completely different things."


Ya mean like "mass" and "energy" ??
;)
Fleetfoot
not rated yet Aug 18, 2012
Since NASA currently has a solar sail operating in space, I'd say it's more than "in theory".


NASA had "NanoSail-D2" flying but it re-entered the atmosphere about a year ago:

http://en.wikiped...oSail-D2

The solar sail currently in operation is the Japanese IKAROS mission:

http://en.wikiped...i/IKAROS

Solar sails work with pressure of solar wind (protons) preferably.


Wrong again, radiation pressure is about 3 orders of magnitude larger than the force from the solar wind.

The pressure of photons corresponding solar constant p = 1328 / 300 000 000 = 4,43x10-6 Newtons per square meter, i.e. way too low for being used in feasible way.


Remember to double it for a mirror. The solar wind pressure is more variable but is usually around 3 to 4 nPa, 2000 to 3000 times less than the radiation pressure.
Fleetfoot
not rated yet Aug 18, 2012
There are really 2 possibilities to reconcile the data. Dark matter or MTOG (modified theory of gravity).


The original was MOND but that failed on many levels, the best known current attempt is TeVeS but that too is now struggling with the latest observations.

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