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Examining the Expected Effects of Dark Matter On the Solar System
First time accepted submitter LiavK writes "Ethan Siegel recently wrote a great post for ScienceBlogs discussing the expected total mass of dark matter in the solar system. As far as we can tell, dark matter only interacts weakly, via gravity, both with itself and normal matter. So, it can't collide with itself, meaning that it has no way of getting hotter and radiating away energy and momentum. This means that it remains a diffuse mess, with a density that is ridiculously low, to the point where detecting its local effects is likely to remain... challenging for the foreseeable future."
As opposed to the ether of the 19th century, quantum fields, which are what we currently use to explain everything?
Michelson and Morley found that the hypothetical ether had no detectable effects.
In contrast, scientists started by measuring orbital velocities and could only explain them with dark matter.
The problem with dark matter observation in this case is that science is based on empirical observation. If you can't see it, can't measure it, and can't even draw inferences from what you can see and measure to detect something indirectly... it's not science. What this is saying is that the effects are so miniscule that there is no equipment presently capable of separating an actual effect or observation from systemic inaccuracy in the equipment itself. That is, you can't tell whether it's just random 'noise' or an actual signal.
As I understand it, there's a big empty space in most of our theories and observations that says something should be filling it up, but we have very little in the way of actual data of what exists within this hole. We can infer something is needed to balance out our observations, but we haven't actually seen the 'something'. It's like a shy cat in an apartment. You won't see that cat again, and an exhaustive search of most of the rooms in the apartment comes up empty, but something keeps eating the cat food. Thus, we have concluded there's a cat in the apartment... but nobody has actually ever seen the cat.
#fuckbeta #iamslashdot #dicemustdie
It can't collide with itself? Good to know that the Majorana versus Dirac particle question is settled then. Oh, wait...
Of course, I didn't bother to RTFA...
Dark energy, the Ether of the 21st century.
I come here for the love
Rebuttal: Bullet cluster.
Dark matter, the Ether of the 21st century.
Right you are, mate. I mean, have you tried sniffing that shit? That will get you tall faster than you can say Patrick Moore.
Ezekiel 23:20
My bet is that the need for dark matter will disappear when relativistic effects are properly taken into account.
And I bet that at some point during the last few decades of thousands of observations, theories, and calculations by thousands of astronomers, physicists, and mathematicians (some with Nobel prizes, no less), someone would have already thought of this if it was an issue.
systemd is Roko's Basilisk.
Or you could say space has a property of localized time. Which means time doesn't scale or progress uniformly throughout the universe. If you've got enough gravity, it's going to make things appear even more massive then they are because of time dilation. The relationship of gravity vs. time also means c should be treated as a coefficient rather than a constant. (The effective value of c still remains fixed, but that's because relationship of distance vs. time has both parts as variables. Time effectively rescales itself at higher energies to maintain c for a given distance traveled by a particle, but if you don't account for that, the extra momentum approaching or exceeding c looks like a gain in mass.)
Somebody with better math skills than myself could probably re-jigger Special Relativity in this regard and account for missing mass. It may even show a cumulative effect with gravitational time dilation when you have a system of multiple orbiting objects. But you might also have to toss the idea of a "Big Bang" out the window. (Makes "age" of things in the universe fairly irrelevant when a localized second is defined by the gravitational or acceleration field it's being measured under. Not to mention under certain conditions the typical light-year measuring stick astronomers like to use will also look about as uniform as a funhouse mirror. The funny-sounding Dr. Who sci-fi explanation of time being "Wibbly wobbly" may have some real logic to it.)
Of course it sounds nutty, because it opens up a lot of loopholes. Probably explains why Einstein was uncomfortable with some things, even if it provided the template for a more accurate model than some later revisions.
It's an energy field created by all living things. It surrounds us, penetrates us, it binds the galaxy together.
Actually, it doesn't really in any way. Unless you think the only relevant property of the ether was that it permeated all space, in which case there is a bunch of stuff in science, past and present, that fits that description, anywhere from various potentials to other various fields. Might as well complain heliocentricism sounds just like geocentricism because they both involved spinning things.
They're not gods
No, but I think it's reasonable to assume they're a bit ahead of the average Slashdot poster in this department.
(and there's no Nobel prize for mathematics).
Two ways out of that one:
a) as it was meant to be read:
by thousands of [ astronomers, physicists, and mathematicians ] (some with Nobel prizes, no less)
b) I didn't say what they won the Nobel prizes for. Mathematicians have won Nobel prizes.
systemd is Roko's Basilisk.
This is probably a dumb question, but I've been wondering about it for something like a decade, and I never see it referenced (even to debunk it) in legitimate science discussions.
A mysterious effect which looks like matter, but is invisible except for its gravitational effect. A second mysterious effect which causes the rate-of-expansion of the universe to increase.
I grow more and more skeptical of string theory and its relations every year, but the first of those definitely sounds to me like matter that's in another brane. The second one seems (to my non-physicist mind) like it could also be explained by the same thing, just a different set of matter in a different position relative to the first.
If our universe really is a 3D brane in a hyperdimensional space with others, isn't this exactly the sort of thing we'd expect to see? Further, wouldn't we see related effects like neutron stars unexpectedly flashing into black holes when they come into close-enough contact with dense clumps of matter in adjacent branes (IOW, when there's not enough observed mass in our own to explain the change to a black hole)?
"...always new atoms but always doing the same dance, remembering what the dance was yesterday." -Richard Feynman
My bet is that the need for dark matter will disappear when relativistic effects are properly taken into account.
There seems to be the belief among astrophysicists that general relativity can be safely ignored when speeds are low. I'm not so sure.
The situation you are talking about, where speeds are low, concerns special relativity, and it's obvious that low speeds do not make much of a difference. This isn't some "guess" that astrophysicists are making. It's a direct result of what special (and therefore) general relativity says. And astrophysicists do use general relativity.
The Higgs field is just the latest one. Quantum field theory (what people mean today when they say "quantum mechanics") includes a field for every fundamental particle. Yes, the ether won.
Don't make the mistake of thinking there was just one ether theory. There were lots of them, many quite compatible with special relativity. Quite a few that sound like 1890s versions of quantum electrodynamics.
Are you describing tentacle porn?
Learn to love Alaska
That's because when you say things like that you check off quite a few boxes on the crackpot criteria.
It's not a religion. Lots of different dark matter theories and alternatives have been proposed and tested. The problem is that when some random Slashdotter comes along and says "dude, it must be something else!" the actual astronomers, and the amateurs who can read, roll their eyes. When the same Slashdotter then says "dude, you're not taking me seriously because you can't get past your religious dogma!" said astronomers and literate amateurs roll their eyes harder.
This is a sig I've seen someone use on /. the article says to me dark matter was here, then nothing exploded.
The 2dF Galaxy Redshift Survey http://scienceblogs.com/startswithabang/files/2013/07/kozm_LSS.jpg
shows stuff coming towards us. I've heard so many space programs say everywhere you look everything is moving away from us,
Obvious?
A coil of wire with electrons moving at mere centimeters per hour is enough to exhibit relativistic effects (magnetism).
They found that that the effects predicted on the basis of analogy with material science were not measurable.
But then came general relativity, quantum fields, dark energy, etc., and we decided an empty vacuum wasn't actually empty after all.
If you never read the works of the "priests of science", you aren't qualified to say that they were wrong, or they have missed an obvious solution to a decades old problem.
Unless, of course, you actually solve the problem. But you're not going to get much respect by randomly throwing around some terminology from high school science classes and saying you're better than all those people who had spent years and years of studying the subject matter.
Don't quote me on this.
You've got a bit mixed up here. The entire idea of dark matter is because we can measure something we can't see - there are gravitational effects but not electromagnetic ones that have been seen yet.
It's more like stepping on a black cat in the dark. You've felt it underfoot for an instant and it's run off somewhere, so while you don't know what it is or where it is you do have empirical evidence that you've stood on something.
Understanding the universe has been a good investment in the past. There is good evidence for something that behaves like dark matter on galactic scales. If it isn't dark matter it might be something more interesting.
When people will not even imagine the possibility that what they believe could be wrong then I would call that a religion. I personally don't believe that dark matter exists, but that won't stop me from reading about it and studying the evidence if it is actually found and believing once I see the truth.
I keep my mind open, not closed to possibilities I have never imagined.
Star Trek, there maybe hope.
So who is it you're accusing of the religion of dark matter? The astrophysicists who've spent the last twenty years thinking up all sorts of crazy ideas for what it might be and then testing those ideas?
> someone would have already thought of this if it was an issue.
Then please tell me who has already thought of explaining the expansion of the universe by considering the matter-to-energy conversion occuring within stars and realizing that the disappearing matter reduces space curvature, expanding it. Accelerating star formation and total power output would thus produce accelerating expansion of the universe. Do try to find any astrophysicists who has done these calculations. I'd be very interested to read their papers.
That still does not explain empty space having detectable mass in the form of gravitational lensing.
Ah, I understand. You're talking about people who are skeptical of your favourite off the wall theory. That's not religion. As the thread before your post said, when Slashdotter 214243 comes along with some theory from left field, along with an assertion that the experts (some of whom have Nobel prizes), who have put careers into looking into this question, are wrong (or religious), he better have some good evidence to support it. Every time I've seen it that "evidence" boiled down to a vague, usually incorrect understanding, usually with a healthy dose of conspiracy theory.
Maybe you've seen something a little more solid? Care to share?
This may or may not relate to dark matter, but the other day, an electrical storm was passing over my house, and I momentarily saw a dark spot on the wall. Is there a scientific explanation for such phenomena? I've never had visual disturbances like that otherwise.
I find more and more that people trying to argue against dark matter are acting like dark matter is some religion to researchers, they think that proposing or discussing an alternative will brand them a heretic and things go undiscussed at the professional level (even if your charge here is not about actual scientists and only their followers). Way too many people act like the alternatives are completely ignored, and pushed away, despite their being whole research groups at many universities dedicated to some of the alternative theories, which are welcomed and frequently very popular talk givers because of their alternative views. Although nearly every such talk I've been to either directly, or in questions, has the talk giver say they still think dark matter has a better, more complete explanation of observations than their theory.
Then please tell me who has already thought of explaining the expansion of the universe by considering the matter-to-energy conversion occuring within stars and realizing that the disappearing matter reduces space curvature, expanding it.
Well, you have, so why don't you do the calculations, write a paper, and win a Nobel prize? From my point of view (that of not being an astrophysicist and only have an interested reader's grasp of the subject) you're the one making the claim, so it's on you to find the evidence.
Besides which, I was under the impression that energy warps space just as mass does (though perhaps you're referring to mass/energy being lost to the space around the star by radiation).
I was also not aware that if you remove mass from a volume of space the space within that volume begans to expand faster.
systemd is Roko's Basilisk.
So, it can't collide with itself, meaning that it has no way of getting hotter[...]
Wouldn't gravitational interactions count as "colliding", at least for the purpose of exchanging energy? And the fact that it can't radiate away energy has more to do with it not interacting electromagnetically than its ability to collide with itself, hasn't it?
Let me know when they find supporting evidence [of dark matter]
You mean like the rotational curves of galaxies, the velocity dispersion of stars in galaxies (including observations of globular clusters with very little dark matter, leaving MOND with even more problems), gravitational lensing (including the bullet cluster), fluctuations in the cosmic microwave background etc.?
Mind you, I can't forward a better theory to explain why things have mass
Dark matter has nothing to do with why things have mass. That would be the Higgs field (or, rather, why fundamental particles have mass. Most of the mass of normal matter has another explanation).
You're no pun anymore.
Ezekiel 23:20
Am I the only one who thinks about the Pioneer anomaly after reading this article?
If there is a constant density of dark matter in the solar system it will have a too small effect on Neptune to be detected. When moving further away from the sun the effect of the dark matter becomes stronger. So if we want to detect its gravitation we have to go as far away from the sun as possible. We should see something like the Pioneer anomaly, but we probably have to send a probe much farther out to detect any effect.
Then please tell me who has already thought of explaining the expansion of the universe by considering the matter-to-energy conversion occuring within stars and realizing that the disappearing matter reduces space curvature, expanding it. Accelerating star formation and total power output would thus produce accelerating expansion of the universe. Do try to find any astrophysicists who has done these calculations. I'd be very interested to read their papers.
E=MC2 is an equivalence, not a transformation.
The subject who is truly loyal to the Chief Magistrate will neither advise nor submit to arbitrary measures (Junius)
> I was under the impression that energy warps space just as mass does
No it does not. Photons have no rest mass and their relativistic mass is negligible.
> I was also not aware that if you remove mass from a volume of
> space the space within that volume begans to expand faster.
Imagine space as a stretched napkin. Drop a salt shaker in the middle and see the napkin take a "gravity well" shape. The edges will move inward, reducing the projected surface area. Likewise, in space, matter warps space, pulling it in toward itself and thereby shrinking the universe. Convert that matter to light and space unwarps itself, expanding the universe.
> Well, you have, so why don't you do the calculations, write a paper, and win a Nobel prize?
Considering that all my comments get modded down, I'd wager that any paper I write on this subject will not pass peer review, whether it is correct or not. As for the calculations, they have already been done and published by Randall Mills, the quack from Blacklight Power. Naturally, everyone assumes that just because he has one quack theory, everything he says must automatically be wrong. Feel free to read his book and verify his calculations (the cosmology section is not really dependent on his quantum mechanics).
Here's the thing. We "followers" may not be able to do the science ourselves, but we can both read the papers and look at who and how many scientists are working on X theory, and who and how many scientists are looking at Y theory, get a feel for it on a high level, and come to a conclusion. And that is assuming that we're all minimally proficient in science ourselves, when in reality, many of us have been carefully keeping up on these theories for decades on an amateur basis and have fairly good science educations to boot.
We need to remember that while humility is a virtue, false humility is not. If you've done the work on something, you've checked it, and most of your peers agree with you, you're probably some semblance of correct. Maybe not completely correct, but being a little wrong doesn't mean that you completely throw out your approach if it is explaining the empirical results well.
We know that weakly interacting matter exists, we know that there are lensing events that do not look like lensing events from normal baryonic matter. Therefore a weakly interacting matter makes a lot of sense. Sure, it could be all cancelled out by some unknown "correction" to Relativity, but so far, that's just a completely separate, even less developed approach than the Dark Matter hypothesis would be. And of course, you or anyone else is welcome to work on it, but in the meantime its just a phantom alternative that really has no standing to cause work on the Dark Matter hypothesis to stop.
You're making a classic mistake there. When matter gets converted into energy gravitation doesn't care. It cares about the total mass-energy. Which doesn't change. So while the emitted photons do not have mass they do have energy which of course has a mass equivalent.
In a closed system* even if there are nuclear reactions taking place the mass-energy of the system does not change.
*to actually do this you'd have to contain all the mass and photons and neutrinos, which we don't know how to do, but the point stands...
"The weirdest thing about a mind, is that every answer that you find, is the basis of a brand new cliche" -
No it does not. Photons have no rest mass and their relativistic mass is negligible.
But not zero. And in case you hadn't noticed the bright shiny orb in the sky, you get a lot of photons when you convert matter to energy, and their total energy will be equivalent to the total mass converted. I'm sure there's a formula for it somewhere...
Convert that matter to light and space unwarps itself, expanding the universe.
If that's the case - and I'm not at all clear why you've concluded that the universe would expand in any real sense just because some part of space is less warped than it used to be - it's only because the light leaves the local area. But then that light will act to warp whatever space it travels through, leaving the totality unchanged.
Feel free to read his book [amazon.com] and verify his calculations (the cosmology section is not really dependent on his quantum mechanics).
I could just as easily suggest that you read this review and verify the reviewer's claims. It'd be a hell of a lot cheaper, for one thing.
systemd is Roko's Basilisk.
Except that electromagnetism IS a relativistic effect. You don't have electromagnetism without relativity.