The Search for Dark Matter Is Dramatically Expanding (wired.com) 55
Ever since astronomers reached a consensus in the 1980s that most of the mass in the universe is invisible -- that "dark matter" must glue galaxies together and gravitationally sculpt the cosmos as a whole -- experimentalists have hunted for the nonluminous particles. From a report: They first set out in pursuit of a heavy, sluggish form of dark matter called a weakly interacting massive particle, or WIMP -- the early favorite candidate for the cosmos's missing matter because it could solve another, unrelated puzzle in particle physics. Over the decades, teams of physicists set up ever larger targets, in the form of huge crystals and multi-ton vats of exotic liquids, hoping to catch the rare jiggle of an atom when a WIMP banged into it. But these detectors have stayed quiet, and physicists are increasingly contemplating a broader spectrum of possibilities. On the heavy end, they say the universe's invisible matter could clump into black holes as heavy as stars. At the other extreme, dark matter could spread out in a fine mist of particles thousands of trillions of trillions of times lighter than electrons. With new hypotheses come new detection methods. Kathryn Zurek, a theoretical physicist at the California Institute of Technology, said that if current WIMP experiments don't see anything, "then I think there's going to be a substantial part of the field that's going to shift into these new kinds of experiments." Already, the work has begun.
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>His robot car has already killed three people.
Wait until you find out how many people *human* drivers have killed.
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Wait until you find out how many people Tesla Autopilot has saved..
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As a result, under President-elect Joe Biden, the alliance that the government has with SpaceX is likely to end.
Yes, Biden is likely to end what Obama started. Riiight.
Re:There is no dark matter. (Score:4, Informative)
Dark Matter as astrophysicists currently describe it, forms a large halo around the galaxies. For our galaxy, that halo would be 100,000 light years in diameter, and still only contain five times the mass than the visible matter. That would mean that within the limits of our Solar system, where we have huge concentrations of visible matter, their influence dwarfs that of Dark Matter, which does not clump together the same way, as it is not able to heat up in the clumping process and thus release the energy as electromagnetic wave.
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Rather than posit multi-dimensional theories, I wonder if recent measurements by Voyager 1 and 2 of the interstellar medium has had any effect on the "missing mass", since they have found it to be denser than expected.
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Interesting that you mention the Voyager probes. These are the furthest objects mankind has send out into space. Years ago did someone at ESA tell me that despite best efforts these probes aren't where we expect them to be according to our math. I don't remember if the probes are too far or too near for where these should be. Could be the models for the solar wind have improved or other models and measurements have improved and the discrepancy has been explained by now. But the Voyager probes are a test of
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I think you're thinking of the Pioneer Anomaly, not Voyager. Voyagers are stabilized with gas jets, Pioneer was spin-stabilized. When the Pioneer data was finally analyzed (after NASA staff risked their jobs to defy the Bush White House direct order to destroy the data and instead handed the tapes over to the Planetary Society) it was found that the extra velocity was contributed by heating of the onboard electronics and the RTG.
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No, I do really mean the two Voyager probes.
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Voyager is more problematic in positioning, as it uses gas jets for stabilization. They add or remove a small amount of velocity every time they're fired, and they're fired fairly often (still). While you might well be correct their location wasn't an issue that I had heard of.
The Pioneer probes uses spin inertia to stabilize themselves, so their location could be predicted much more precisely. Strangely their actual position deviated from predictions by a small but undeniable amount, which was dubbed th
Re:There is no dark matter. (Score:5, Informative)
And if Dark Matter only works gravitationally, you can use Newton's insight that within a homogeneous sphere, all gravitational pull from outer shells cancels out, and the amount of matter of less distance than the test mass (e.g. Voyager 1) from the center can be thought of as being concentrated in a single point at the center. The Solar system weighs about 2 * 10^30 kg, and Voyager 1 with about 850 kg mass is currently at 22.5 * 10^9 km away from the Sun. That means that currently, the Voyager 1 probe experiences a gravitational pull of about 2.5 * 10^(-4) Newtons just from the visible matter in the Solar system.
The whole Galaxy has about 2.5 * 10^42 kg of Dark Matter, distributed evenly in a sphere of about 200.000 light years diameter. That means, that within a sphere of 300 AU, which is about 0.005 light years, there is 3*10^19 kg of Dark Matter. This is about 1/30 of the mass of the dwarf planet Ceres. That would amount to a gravitational pull of 10^(-15) Newton.
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The whole Galaxy has about 2.5 * 10^42 kg of Dark Matter, distributed evenly in a sphere of about 200.000 light years diameter.
Is it? "Distributed evenly" seems very unlikely.
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Really you got proof of that? Come on bro, the existence of matter trapped in other dimensions is even more exotic and fanciful than dark matter -- Occam's razor fail. Also, how can you be sure it would clump near the Sun? You seem to know whether or not dark matter can repel itself or not. Even normal matter hasn't massively clumped near the Sun -- and normal matter actually can have friction by collisions and lose energy which would enable to fall towards the Sun .. most dark matter in the Sun's vicinity
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Really you got proof of that? Come on bro, the existence of matter trapped in other dimensions is even more exotic and fanciful than dark matter
Dark matter theory is complicating itself into a Baxter of California Five-Blade Razor fail.
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The Planck constant (Score:2)
I would rather question the Planck constant, because it currently limits us in what we accept as a possibility to be out there. What if there was a finer structure to the universe than we can currently detect? 80% of all matter is Dark Matter and we only see 20%, and yet do we rely on the 20% to tell us exactly what all the rest of it is. It strikes me almost as desperate. Like saying, "We're sure the rabbit hole stops around the next corner!" when you can literally not see a thing. What if there was a new
Re:There is no dark matter. (Score:4, Informative)
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But since dark matter only interacts through gravity, it doesn't clump.
That sentence does not make any sense at all. Because it only interacts via a clumping force aka gravity it does not clump?
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What he means by clumping is that Dark Matter doesn't form complex structures as far as we know.
Take gasses as an example. Gasses are influenced by gravity. Gravity compresses gasses, but it doesn't necessarily cause gases to form complex molecules. Dark Matter then does collect and so compresses into regions of space, but without forming anything more complex that we can see.
That said, I can imagine that it first requires more gravity before it clumps. This would explain why Dark Matter is found outside of
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The gravitational effects we observe are a result of normal matter that is trapped in one of the other dimensions that M-theory describes, however its gravity does still affect us.
Do you have any references supporting that statement? Rhetorical question. You do not.
If there was truly such a thing as dark matter, we would see it messing with the orbits of the planets in our own solar system as it would clump near the sun.
You apparently have little to no idea about the average density of dark matter as indicated by all observations of galaxy and other constellation behavior to date, or you would not make that statement.
Conclusion: You are speaking nonsense.
Of course it is! (Score:5, Funny)
The whole universe is expanding, so it stands to reason that the search for dark matter would be too.
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Is it notable that the Universe is expanding at the same rate as we are able to observe it?
Conversely, at some point does astronomy make it too difficult to maintain the simulation, or do conventions such as 'c' keep processing down?
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It is called the Anthropic Principle. The Universe implements every idea man has about it the moment a man or woman has it.
By the way, the simulation is just mathematics and is just a model, stop confusing mathematics with reality.
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go scold Plato with your worn our world view
The path to revision (Score:2)
The kludges we build in to make everything work is just that, kludges. It is like thinking of waves and particles instead of fields.
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The kludges we build in to make everything work is just that, kludges. It is like thinking of waves and particles instead of fields
And what do you mean by "kludge"? Measured in multiple ways by multiple teams, there is matter that is affecting the universe that does not react like baryonic matter. I’m sure you are able to explain what physicists have not been able to explain for a few decades now. Perhaps you should present a paper with your ideas.
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What happens is that quantum particles do not have mass until they cluster together in sufficient density that they gravitationally displace other quantum particles and that displacements is proportional metered out based upon distance and clustered density. From photons clusters of quantum photonic particles, particle and wave, think of the particles as flotsam and jetsam floating on waves travelling much slower than the waves but still oscillating to the quantum particle waves. When it comes to subatomic
Re:Luminiferous aether alert (Score:5, Insightful)
Children will laugh at you - so why do we believe such things to be true?
The real world behaves quantum mechanically. It doesn't matter if children laugh, a child's intuition has no bearing on the veracity of a matter. The failure of analogies to simplify non-intuitive explanations is why Feynman often argued against them (though he did use a water wave analogy to show where it immediately fell apart)
No child would have predicted a diffraction pattern could appear when emitting single electrons through a double slit, it simply isn't in everyday experience.
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... Hence, we acknowledge that the electromagnetic spectrum is a wave, but have cognitive dissonance, in that we believe light is a particle and yet it constitutes a small fraction of the electomagnetic spectrum. We might get over that with ideas like wave particle duality, but seriously, throw a stone in a pond, and tell a kid it's a particle because you're watching it. Children will laugh at you - so why do we believe such things to be true? ...
The problem is that we keep associating a particle with something solid, hard and perhaps indivisible when we shouldn't. We did this with the atom, too, hence the name "atom", until we've learned it can be split. We really shouldn't assume any known shape or characteristic for our models, but it's what we do, because it's how our imagination works.
Imagination builds upon the things we know. Imagination is one of our greatest tools in the box, but it can become our greatest weakness if we allow ourselves to
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It seems that 100 years of "science" has only brought us forwards in showing us how the universe doesn't work as we thought.
100 years of science has brought you the very real benefits in life you enjoy every day. Relativity, quantum mechanics, all the wonderful voodoo you think is just a bunch of old guys who desperately need haircuts navel-gazing while pondering the universe are to thank for very simple things you take for granted, such as the ability for your phone to tell you when you need to turn left, or to hear that whatever the hell you ignorant people listen to on your CD players, that is assuming that you don't just str
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If they discover Season Four of it I'll be happy (Score:1)
Good luck. (Score:2)
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Expanding in which sense? (Score:2)
Does "expanding" really mean, more search is conducted by more experiments or does it mean, that the potential search space has expanded, because more (and more exotic particles) have to be accounted for? This wasn't really clear from the article.
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There is no reason to assume the search efforts increase like it was a missing person we're searching. It will mean they'll have to accept a wider range of theories. I cannot imagine that failing to find an answer would be grounds to throw more money at it. Life on planet Earth will continue with or without mankind having a full understanding of the universe. When we cannot find an answer today should we shelf the problem for now, chase other problems, and in time take another look at it. I'm not saying to
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Dark Matter can wait.
Had scientists used the same logic in the last two centuries, we would still be using steam engines and we wouldn't have electricity and radio, because that strange phenomenon about sparks "can wait". Neither would we have IC chips because quantum mechanics "can wait".
Fortunately, most scientists were not so short-sighted and arrogant to think that any mortal could guess which scientific discovery "can wait" or not.
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Had scientists used the same logic in the last two centuries ...
Spare us the drama. Clearly you still need to learn when to take a break.
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Does "expanding" really mean, more search is conducted by more experiments or does it mean, that the potential search space has expanded, because more (and more exotic particles) have to be accounted for? This wasn't really clear from the article.
No, no, no. Dark energy is rapidly expanding the universe itself, if we don’t hurry up and measure dark matter now it’s going to drop off the visible horizon and if you think people don’t believe it’s real now, just wait till it drops off from causality.
Black holes as dark matter? (Score:2)
Could someone explain how small or small-ish black holes could be an option? Interactions between black holes and ordinary matter are violent. If there was a halo of black holes around our galaxy (and others) shouldn't we occasionally see huge bursts of energy when they accidentally crashed into ordinary matter. Also, even if the black hole had no accretion disk at first, shouldn't it get one over time from random interactions with matter (and thus be visible)? Also, shouldn't conservation of momentum mean
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We are talking about very small black holes, probably size of a marble.
Their interactions you do not really notice, we could have one (some?) in the core of the earth and it would take billion of years until someone realizes.