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Simulations Predict Where We Can Find Dark Matter
p1234 writes with this excerpt from the Max Planck Institute for Astrophysics:
"Simulations by the Virgo team show how the Milky Way's halo grew through a series of violent collisions and mergers from millions of much smaller clumps that emerged from the Big Bang. ... If Fermi does detect the predicted emission from the Milky Way's smooth inner halo, then it may, if we are lucky, also see gamma-rays from small (and otherwise invisible) clumps of dark matter which happen to lie particularly close to the Sun. ... The largest simulation took 3.5 million processor hours to complete. Volker Springel was responsible for shepherding the calculation through the machine and said: 'At times I thought it would never finish.' Max Planck Director, Professor Simon White, remarked that 'These calculations finally allow us to see what the dark matter distribution should look like near the Sun where we might stand a chance of detecting it.'"
We discussed a related simulation a few months ago.
I can't believe no one has tried looking for dark matter directly next to the Sun. That should light it up!
"I wonder if dark matter to them is like a Ubuntu release to most of us?"
Maybe, the answer is difficult, it's much like Schroedinger's cat.
until it's observed you cannot tell if it is there or not.
https://www.gnu.org/philosophy/free-sw.html
Just look in Nibbler's litter box.
Instead of a gamma-ray glow map as seen from the Sun, I'd like to see 3d renderings of a whole galaxy where they artificially color dark matter to show where it is.
Don't bother reading the paper. They discovered that they could find dark matter "in space" if it exists.
Did you read the same article I did? Before this simulation their best guess was to look at other galaxies and target their centers. However, the simulation revealed that they have a better chance if they look at our own galaxy, but 10-30 degrees of center, where they should be able to detect gamma rays caused by dark matter.
Actually, I was just trying to be silly. ;)
"Did you read the same article I did?"
this is slashdot, read the article, who has got time for that?
https://www.gnu.org/philosophy/free-sw.html
With the way physics is goign these days, being able to determine that something is in space means you are doing pretty damn good for yourself.
I may agree with what you say, but I will defend to the death your right to face the consequences of saying it.
I wonder if dark matter to them is like a Ubuntu release to most of us?
Actually it's more like fudge.
"Nobody knows the age of the human race, but everybody agrees that it is old enough to know better." - Unknown
Sounds like with that many computer hours needed they should set up something similar to Seti@home
It's only paranoia if your wrong...
hours to predict, if it only took the computer that long what took them so long to figure this out.
that sounds a pretty useless measurement
my mid range processor does about 0.5GFLOPS, which means those available on the market probably range from about 0.1-2GFLOPS give or take, and then theres graphics processors, which are capable of TFLOPS these days, so there could be a factor of about 10^4 in the number of FLOP's done, i know that astrophysics often has order of magnitude calculations, but that's just a bit useless
I find plenty of dark matter when I turn out all the lights prior to going to bed for the evening.
Specifically, I find plenty of dark matter with my toes, which doesn't result in a shout of discovery like, "Eureka!" but ,"*$&#@!"
LAUNCELOT: Look, my liege!
ARTHUR: Camelot!
GALAHAD: Camelot!
LAUNCELOT: Camelot!
PATSY: It's only a model.
ARTHUR: Shhh!
Ezekiel 23:20
Rofl
... also knows where it can find dark matter. And it doesn't need teraflops to do so !
Votez ecolo : Chiez dans l'urne !
"I wonder if dark matter to them is like a Ubuntu release to most of us?"
That dark matter is a annoying phenomenon?
Maybe, the answer is difficult, it's much like Schroedinger's cat. until it's observed you cannot tell if it is there or not.
Schroedinger's cat is definitely there. It's also not "dead or not dead" it is "dead and alive at the same time". Quantum boon!
Due to the proximity to the Sun, the Galactic centre is the brightest and most extended source. This makes it easier to detect than any of the small dark matter subclumps that are distributed over the sky. If one of them should also be detected, it may be devoid of any stars.
I'm interested in that last sentence. Does the gamma radiation push away hydrogen and dust, preventing the formation of stars, or does dark matter exhibit a repulsive gravitational force, clearing a region of space around it? Without referring to Wikipedia, the latter seems unlikely, but the former seems like something we should worry about. How much gamma radiation are we talking about? Should we worry about one of these clumps drifting near the solar system and sterilizing everything? (And if so, how much of an effect would these clumps have on the Drake equation?)
Nothing for 6-digit uids?
....where they should be able to detect gamma rays caused by dark matter...
This assumes that dark matter generates gamma rays, a form of electromagnetic radiation. Has anybody ever scientifically demonstrated that it is possible to generate such electromagnetic radiation by means OTHER than moving electrical charges? If they do detect such gamma radiation, how will they ascertain that this radiation is NOT caused by an electrical phenomena rather than some unknown action of undiscovered dark matter?
Anytime the underlying assumptions of a computer input or algorithm are faulty, even the 3 1/2 million hours of computation on a supercomputer will not lead to the discovery of the scientific truth. The principle of garbage in garbage out still applies. The bottom line is simple: the dark matter emperor is as naked as a newborn.
All theory is gray
Anytime the underlying assumptions of a computer input or algorithm are faulty, even the 3 1/2 million hours of computation on a supercomputer will not lead to the discovery of the scientific truth. The principle of garbage in garbage out still applies. The bottom line is simple: the dark matter emperor is as naked as a newborn.
They have a theory about how dark matter should work. They expended 3.5M hours of computing to make a prediction based on that theory. Now they'll try to confirm the prediction empirically. If the prediction doesn't pan out, the theory will be jettisoned or patched. If the empirical observations agree with the prediction, the theory is left standing until such time as new evidence shows it to be squidgy around the edges. That's how science works.
"Has anybody ever scientifically demonstrated that it is possible to generate such electromagnetic radiation by means OTHER than moving electrical charges?"
Yes. Go to a large hospital that has a PET scanner. They routinely generate gamma rays inside human bodies through the annihilation of positrons and electrons.
Gamma rays are generated by interactions that involve atomic nuclei or particle-particle interactions. Because of that, in most processes the gammas all have specific energies. For example, in the electron-positron annihilation, usually two gamma rays are produced, each at 511 keV.
Accelerating electrical charges tend to radiate across all or a large portion of the spectrum unless the acceleration on all of them is identical. The article says the researchers recommend looking for large regions of smoothly varying gamma intensity. That's not a pattern that would be easy to produce with acceleration, particularly not at a uniform energy.
This assumes that dark matter generates gamma rays, a form of electromagnetic radiation. Has anybody ever scientifically demonstrated that it is possible to generate such electromagnetic radiation by means OTHER than moving electrical charges?
You are quite correct. They are making a huge assumption that dark matter can annihilate with itself. Whether it can do this depends on the type of dark matter - in some models it can in others it cannot. This is not pointless though - their work will either see it or at least put a limit on how well it does annihilate which we may be able to use to give us a better idea where to look at the LHC.
One way to avoid having charges produce photons is to have your particle partly consist of the EM field. For example, although the experiment has never been done, I think (if you are a particle theorist feel free to correct me!) you could annihilate two Z bosons to give two photons because the Z consists partly of an EM field.
If they do detect such gamma radiation, how will they ascertain that this radiation is NOT caused by an electrical phenomena rather than some unknown action of undiscovered dark matter?
When you have an annihilation like this the photons produced are mono-energetic. Hence you will get a large spike in the emissions at a particular energy value. Since dark matter has a mass in the 10's of GeV minimum (for most models) this would be extremely hard to produce by other means and certainly not in a mono-energetic fashion. Of course, this is not concrete proof that it comes from dark matter but if all the physics we know about cannot explain it then it would have to be dark matter or something else completely new.
they already found some dark matter under Uranus.
At least that narrows it down a bit? Oh...
...through the annihilation of positrons and electrons....
You not say that electrons or positrons are not charged and are not moving when they annihilate? What I am saying is that gamma rays are produced by electrical effects rather than gravitational interactions involving mass. Maybe I am wrong, but I was under the impression that one of the big reasons of postulating dark matter is to account for the motion of galaxies. The reason that dark matter and dark energy have not been found is really very simple: they are the figment of mathematical imaginations, not based on physical reality as determined by observations and experiments.
There is a confusion in science today that mixes up mathematics and observed physical reality. Mathematics is a good means of describing physical reality, nothing more.
All theory is gray
The radiation when an electron and a positron annihilate do not come from movement, or acceleration.
I think you need to study up a bit on basic physics before you criticize the world's leading astrophysicists.
"Moving electrical charges" and "electrical effects" suggests you're talking about Maxwell-law electrodynamics. There are many other sources of electromagnetic radiation, including atomic state transitions (e.g., fluorescence) and particle interactions (e.g., radioactive decay, particle annihilation, etc.).
Saying that electromagnetic radiation is produced by "electrical" effects is something of a tautology, as electromagnetic radiation is, as you might guess, an electromagnetic effect. However, it's well-known that there are ways of producing photons other than Maxwell electrodynamics.
...Saying that electromagnetic radiation is produced by "electrical" effects is something of a tautology, as electromagnetic radiation is, as you might guess, an electromagnetic effect....
Exactly, but then why is dark matter and energy postulated to exist, yet it has so far at least never been found to exist in anything other than mathematical speculations? If this postulated of dark matter produces any electromagnetic radiation, would that not of necessity mean that electrodynamic processes were involved?
Everything I have ever read as to why astronomers and astrophysicists tell us the universe must consist of mostly dark matter and energy, is to explain the motions of galaxies as governed by the force of gravity alone. If an addition to the force of gravity, the electric forces also taken into account in the operation of the large-scale universe, dark matter and energy become unnecessary. Incidentally, the same can be said for the fictional construct of black holes. They are also a purely mathematical construct without observational or experimental evidence. All of the puzzling observations coming in from probes sent out into space and advanced telescopes can be explained in a more logical manner, if BOTH the force of gravity and the electrical force are taken into account in the large-scale operation of the universe. One or the other alone leads scientists to scratch their heads trying to puzzle out the "weird" data coming from scientific instruments.
It is observed, that most matter in the universe is not nicely electrically neutral as we have here on earth, but exists primarily in the form of electrically charged particles in violent motion. Ignoring the electrical force which is 39 orders of magnitude greater than gravity, cannot possibly give us a complete picture of events nearby or in the distant reaches of the universe.
All theory is gray
Aaash. This *again*? I still maintain that it will *always* be there!!!
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
You need to brush up on your basic particle physics. The standard model does not agree with what you state above.
Gamma is just energetic photons, more energetic than X-rays that are commercially produced by slamming electrons into tungsten targets. Gamma is typically produced by nuclear decay and is often where "missing mass" goes via the E = mC^2 so they are not an electron phenomena but a nuclear phenomena.
Apocalypse Cancelled, Sorry, No Ticket Refunds
...Gamma is just energetic photons...
Indeed correct, but are not all photons a manifestation of the electric interaction? In reactions involving the strong nuclear force all energy produced eventually converted to and released as electromagnetic energy. When an atomic or hydrogen bomb explodes, all sorts of exotic fragments of atoms are flying around. However, in the end all that energy created by the conversion of mass into energy is converted into and dissipated in the form of electromagnetic radiation. Nowhere has the force of gravity been observed to be involved in any of this.
Why do cosmologists have to resort to convoluted theories involving gravity and come up with undiscovered and exotic constructs such as dark matter and black holes. The well-known principles of modern electrodynamics can interpret the strange observations coming from space probes and modern telescopes. The relatively weak force of gravity is only secondarily involved.
All theory is gray
I wonder how many days 3.5 million processor hours actually is. I run SETI@home still, I wonder if that's comparable.
We can either dig virgon 6 or farm niblonians, whichever floats your boat.
Gamma is typically produced by nuclear decay and is often where "missing mass" goes via the E = mC^2 so they are not an electron phenomena but a nuclear phenomena.
While some gamma rays come from nuclear decay, that is far from the entire story. Most of the gamma rays we observe from space originate in particle interactions, mostly proton on proton collisions. As two protons interact, a whole slew of different particles are produced, but mainly pions. The neutral pion decays into two gammas.
On the other hand, in many astrophysical sources, blazars for example, gamma rays are produced through inverse Compton-scatterings.
...Gamma is just energetic photons... Indeed correct, but are not all photons a manifestation of the electric interaction?
Photons ARE the carriers of electromagnetic interaction. That does not mean, no other interaction can produce photons. You can have direct production of photons in the strong interaction too.
In reactions involving the strong nuclear force all energy produced eventually converted to and released as electromagnetic energy. When an atomic or hydrogen bomb explodes, all sorts of exotic fragments of atoms are flying around. However, in the end all that energy created by the conversion of mass into energy is converted into and dissipated in the form of electromagnetic radiation.
Again, your understanding of basic physics is lacking. Quite a bit of the energy release in a nuclear explosion is released as energetic neutrons and neutrinos.
Nowhere has the force of gravity been observed to be involved in any of this.
Who claims it has to?
Why do cosmologists have to resort to convoluted theories involving gravity and come up with undiscovered and exotic constructs such as dark matter and black holes.
1. Black holes is a consequence of relativity. Relativity has been proven to be very accurate. And, there is plenty of observational evidence for the existence of black holes. Read up on Andrea Ghez from UCLA. 2. While there is yet no direct evidence for dark matter, there are very strong indications. Take a look at the weak lensing results on the Bullet cluster for example.
The well-known principles of modern electrodynamics can interpret the strange observations coming from space probes and modern telescopes. The relatively weak force of gravity is only secondarily involved.
Sorry to say, but this statement is just utterly wrong and just shows your lack of understanding of basic physics.
....Quite a bit of the energy release in a nuclear explosion is released as energetic neutrons and neutrinos....
That is true, but even then in the end these are absorbed and end up as electromagnetic energy. Neutrinos may travel quite far before this happens to them, but at some point they to will interact with with an atom somewhere and produce electromagnetic energy.
(...Black holes is a consequence of relativity...)
Not at all, in fact relativity prohibits the existence of black holes. Even a theoretical black holes cannot be observed by definition since no light or anything else can escape them, according to the theory. According to relativity, a black hole would have to have infinite mass.
(...Take a look at the weak lensing results on the Bullet cluster for example....)
Quite often in science we make an observation and then try to interpret that observation. After a while, the interpretation is equated with the observation itself.
The lensing, in other words the bending of light has been INTERPRETED to be due to a massive object's gravity. We do observe that light is slightly deflected when it passes by the sun or other massive object. That is all we observe and then we speculate about its cause. In 1929 Edwin Hubble observed that starlight shifted in its spectrum toward the red. This has been known ever since as the "red shift". That is all we observe, starlight shifted to the red. This has been INTERPRETED to be caused by motion as in the familiar Doppler effect. There is evidence that the red shift is caused by the steadily increasing zero point energy of space itself.
There is now increasing evidence that the 39 orders of magnitude stronger than gravity electric interaction is responsible for many of the otherwise inexplicable observations coming from modern telescopes and space probes. I do not understand why the incorporation of the electric interaction into the large-scale operation of the universe should be so controversial and greatly opposed by many cosmologists.
All theory is gray
....Quite a bit of the energy release in a nuclear explosion is released as energetic neutrons and neutrinos....
That is true, but even then in the end these are absorbed and end up as electromagnetic energy. Neutrinos may travel quite far before this happens to them, but at some point they to will interact with with an atom somewhere and produce electromagnetic energy.
Sorry, but neutrinos do not interact electromagnetically.
(...Black holes is a consequence of relativity...)
Not at all, in fact relativity prohibits the existence of black holes.
No it does not. Go back and read up on relativity and then solve the equations. Schwarzschild did this already, however.
Even a theoretical black holes cannot be observed by definition since no light or anything else can escape them, according to the theory.
Wrong again. They still have mass and massive objects interact gravitationally. Or are you implying there is no gravity? And add to that Hawking's ideas of black hole radiation. Again, you need to read up more.
According to relativity, a black hole would have to have infinite mass.
Utterly wrong.
(...Take a look at the weak lensing results on the Bullet cluster for example....)
Quite often in science we make an observation and then try to interpret that observation. After a while, the interpretation is equated with the observation itself.
The lensing, in other words the bending of light has been INTERPRETED to be due to a massive object's gravity. We do observe that light is slightly deflected when it passes by the sun or other massive object. That is all we observe and then we speculate about its cause. In 1929 Edwin Hubble observed that starlight shifted in its spectrum toward the red. This has been known ever since as the "red shift". That is all we observe, starlight shifted to the red. This has been INTERPRETED to be caused by motion as in the familiar Doppler effect. There is evidence that the red shift is caused by the steadily increasing zero point energy of space itself.
Provide that evidence. Apparently Occam's razor means nothing to you. You say that dark matter is absurd because there is no evidence. Then you start talking about zero point energy in nothing more than a hand-waving fashion that is even less compelling than dark matter. You basically self-contradicting your arguments.
There is now increasing evidence that the 39 orders of magnitude stronger than gravity electric interaction is responsible for many of the otherwise inexplicable observations coming from modern telescopes and space probes. I do not understand why the incorporation of the electric interaction into the large-scale operation of the universe should be so controversial and greatly opposed by many cosmologists.
Of course you do not understand, because you lack the very basic understanding of physics. The fact that you talk about electric interaction, when we know the interaction is the electroweak interaction is just further proof of this. On large scales, gravity is much stronger than the electromagnetic interaction.
but are not all photons a manifestation of the electric interaction?
No, photons are the carrier of the electromagnetic force so all electrical phenomina are the manifestation of the electromagnetic force, not the otherway around.
Apocalypse Cancelled, Sorry, No Ticket Refunds
....Then you start talking about zero point energy in nothing more than a hand-waving fashion that is even less compelling than dark matter.....
The difference between conjectured dark matter in the distant reaches of space and the zero point energy, instead the zero point energy has been experimentally measured right here on Earth. It manifests itself in various ways, one of them is called the Casimir effect. This zero point energy, pervades all of space and affects all atomic processes.
(...when we know the interaction is the electroweak interaction...)
This is only one facet of the electric interaction to which all leptons respond to.
(...On large scales, gravity is much stronger than the electromagnetic interaction...)
That is flat out wrong unless the matter subject to gravity is strictly neutral, such as it is, fortunately, right around here where we live. The fact is that most matter in the universe is not nicely electrically neutral, but consists of positive and negative pieces of atoms moving in various paths, as dictated by Galactic, intergalactic or local electric fields. A naked electron or proton existing somewhere between here and the sun is 39 orders of magnitude more sensitive to "feeling" and moving in response to an electric field existing in space than a gravitational field, such as from the Earth are from the sun.
We have abundant evidence of immense magnetic fields associated with galaxies, stars, and planets. The intense magnetic fields observed to exist on the Sun are generated by a correspondingly great electric currents. There is only one way to generate a magnetic field, which is by moving electrical charges (currents). There is also only one way to generate x-rays or gamma rays and that is by means of electricity or electrical atomic activity.
All theory is gray
....Then you start talking about zero point energy in nothing more than a hand-waving fashion that is even less compelling than dark matter.....
The difference between conjectured dark matter in the distant reaches of space and the zero point energy, instead the zero point energy has been experimentally measured right here on Earth. It manifests itself in various ways, one of them is called the Casimir effect. This zero point energy, pervades all of space and affects all atomic processes.
It is really sad that you don't really understand what vacuum energy is, still keep talking about in the most utterly wrong ways. Anyone who knows a little bit of quantum mechanics knows that vacuum energy is the lowest energy state of any quantum system and that this energy cannot be removed from the system. It has nothing to do with what you are conjecturing in your posts.
(...when we know the interaction is the electroweak interaction...)
This is only one facet of the electric interaction to which all leptons respond to.
Amazing, you keep talking about the "electric" interaction. Ask any particle physicist (and mind you, I am one myself), neutrinos do not carry electric charge and hence are not interacting electromagnetically. And mind you, the electroweak interaction is the more fundamental one, not "electric" interaction.
(...On large scales, gravity is much stronger than the electromagnetic interaction...)
That is flat out wrong unless the matter subject to gravity is strictly neutral, such as it is, fortunately, right around here where we live. The fact is that most matter in the universe is not nicely electrically neutral,
Wrong again. Most matter in the Universe is neutral. Only small fractions are not.
but consists of positive and negative pieces of atoms moving in various paths, as dictated by Galactic, intergalactic or local electric fields. A naked electron or proton existing somewhere between here and the sun is 39 orders of magnitude more sensitive to "feeling" and moving in response to an electric field existing in space than a gravitational field, such as from the Earth are from the sun.
We have abundant evidence of immense magnetic fields associated with galaxies, stars, and planets. The intense magnetic fields observed to exist on the Sun are generated by a correspondingly great electric currents. There is only one way to generate a magnetic field, which is by moving electrical charges (currents). There is also only one way to generate x-rays or gamma rays and that is by means of electricity or electrical atomic activity.
And since every particle physicist worth his name can prove you wrong on this point I rest my case. Mind you, I am in the field and I have had the pleasure to know and work with some of the authorities in the field.