New Hubble Release Puts Another Nail In the Coffin of Dark Matter's Competitors (spacetelescope.org)

StartsWithABang writes: When it comes to the structure of the Universe — forming the galaxies, clusters, and Universe as we see it — the normal matter we know of simply isn't enough. Given our best-understood laws of physics, including Einstein's general relativity, what we see of galaxies and the Universe in general simply doesn't match up to our predictions. The simplest solution, arguably, is to just add a new ingredient: a new form of matter, a dark matter if you will. But a counterargument is that we've got the laws of gravity wrong, and that no new matter is necessary. There's only one way to settle an argument like this: with data, evidence and the full suite of observations at our disposal. The newest Hubble release, along with four other independent lines of evidence, rule out modifications of gravity and leave dark matter as the only option standing.

Comments

Handwavium

[Anonymous Coward]

Dark matter is still handwavium. The best proof we have for it so far is that if it isn't there the model we use doesn't work.

Re: Handwavium

[Anonymous Coward]

Thank you. I just can't bring myself to accept dark matter as a viable option. It seems so ad hoc. It is only the best explanation given our current knowledge.

Re:Handwavium

[UltimateRobotLover]

And yet it moves.

Re: Handwavium

[Anonymous Coward]

Thank you. I just can't bring myself to accept dark matter as a viable option. It seems so ad hoc. It is only the best explanation given our current knowledge.

While I agree with you, I am forced to contemplate some of the speculations about how wormholes (if they do indeed exist) and warp drives created without massive singularities as drive components (Read: Impractical) could be constructed and the only working models that have not been ruled as impossible involve some magical stuff referred to as "Exotic matter" of which this dark matter is a proposed type. (This is Non-Baryonic matter I am referring to.) This means that there is more to matter than the standard model predicts and that things like FTL via space warping by some sort of practical means, or the means to travel via wormholes (which includes time travel) and anti-gravity, is still not ruled out.

There is good and bad and intermixed between the two is confounding and confusing until we have the right set of epiphanies.

Re:Handwavium

[Anonymous Coward]

Intuitively I feel the same exactly the same, but as a humble network engineer I acknowledge my lack of expertise in this area. There does seem to be a real consensus among the relevant experts that dark matter exists, even if none of them can tell us what it actually is.

When the consensus is "we just don't know but our theory matches all known practical observations" then I take it seriously. In fact I'm inclined to take that more seriously than if the consensus claimed perfect knowledge.

If you have a better theory I'd love to hear it, but until that time we have to work with what we got.

Re: Handwavium

[Anonymous Coward]

So was the hypothesis of the neutrino before it was actually detected. You see, there was this anomaly in the beta decay spectrum and it was hypothesized that the missing energy was carried away by this particle called a neutrino. Decades later the neutrino was actually detected. In what way is dark matter different?

Re: Handwavium

[Anonymous Coward]

The assumption that FTL is possible and we just have to work out how is not backed by anything more rigorous than Star Trek.

Re: Handwavium

[Curunir_wolf]

So was the hypothesis of the neutrino before it was actually detected. You see, there was this anomaly in the beta decay spectrum and it was hypothesized that the missing energy was carried away by this particle called a neutrino. Decades later the neutrino was actually detected. In what way is dark matter different?

The neutrino hypothesis included some very specific property values for the particle, and possible ways it could be detected. Dark matter, not so much.

Re:Handwavium

[delt0r]

Oh god. Not this again. There really is no better explanation. It may feel handwavium to you, but that is because you are willfully ignorant of the data and the theory. There is more data backing up darkmatter than global warming. Also we go through the same ignorant replies below for this topic.

/. Home of people that think they are smart because they can configure a router, but really its a bunch of illiterate idiots.

Re: Handwavium

[Anonymous Coward]

we need alot of energy to make a very massive singularity in order to affect the bending the time/space in order to create a worm hole once the wom hole is create we have essentially a warp drive and can move through time/space at will this will move our civilization to the next level because we can travel throughout the universe to any location at will all our effort need to be focus on fusion reaction thats how we will be able to create a massive singulatory

Re:Handwavium

[stevelinton]

But that's true of everything. The only reason we know the sun exists is that if it isn't there our model for predicting what we should see
when we look up doesn't work.

Re: Handwavium

[Anonymous Coward]

Incorrect. Dark matter candidates have very much specific properties that could be measured. The axion has certain hypothesized properties and so does the neutralino. Just like the neutrino.

Re:Handwavium

[GrumpySteen]

Well yeah. If it didn't move, it would be hand standstillium.

Re: Handwavium

[Anonymous Coward]

And there's your difference. The neutrino was a specific particle proposed as a solution to a particular observation. Dark matter is just throwing a bunch of shit at the wall and hoping something sticks.

Re:Handwavium

[wonkey_monkey]

The best proof we have for it so far is that if it isn't there the model [which we have created based on our observations of the universe] we use doesn't work.

So... that'd be like... science, then?

Re: Handwavium

[Theovon]

As someone else said, dark matter is an ad hoc solution. We don’t have direct measurement of it. We just have a phenomenon, and we’re trying to come up with different possible explanations and then rule some out.

Currently, dark matter is the leading theory because it explains all the data and it’s also the SIMPLEST explanation.

This doesn’t mean that dark matter theory is TRUE. But as explanatory models, it is RELIABLE. Keep in mind that science can never prove any theory to be 100% incontrovertible, but it can show a theory to be very LIKELY to be true.

And as with any other successful human endeavor, the science here is a competition among competing theories. So far, dark matter theory is the winner, like VHS. (Betamax had better image quality, but VHS was “better” and won because it was an open format. Don’t get too distracted by the imperfect analogy!) Some day, someone will come along with something that explains more evidence and is more concise, like Blueray.

Re: Handwavium

[Anonymous Coward]

No it is not. The neutrino was ONE possible explanation that turned out to be the correct one. A quite famous physicist called Niels Bohr had a different solution to the problem. So not at all different from today, where different people have different ideas how to solve this problem. The scientific way is to follow through and investigate ALL of them.

Re:Handwavium

[ivano]

It's only handwavy because you don't want to take the time to understand the evidence for it and against it. There is a lot of evidence for the WIMP model of dark matter, including the current data just posted and things like the Bullet Cluster.

Re:Handwavium

[thisisauniqueid]

Well-put. The same goes for the big bang.

Re:Handwavium

[Black Parrot]

The best proof we have for it so far is that if it isn't there the model we use doesn't work.

That's kind of how science works: you notice an effect, assume there is a cause, generate some guesses about what that cause might be, and then start weeding them out.

Re: Handwavium

[Anonymous Coward]

The idea of wormholes comes only from that it is possible to construct them mathematically and are based on using singularities as simplified models for black holes.
If you can model black holes as singularities you can negate them and get a model for white holes that expunges matter instead of swallowing it. (Never observed, just extrapolated from math.)
The matter has to come form somewhere, possibly the black holes. As a result you have a wormhole theory.

Re:Handwavium

[Richard_at_work]

A lot of physics is simply at the "placeholder" stage, as we know next to nothing about it - how does gravity work? How does magnetism work? We can say there are gravity waves and magnetic fields but we don't actually understand the underlying mechanisms of either, yet they form the cornerstones of a lot of our current understanding of the universe around us.

Re:Handwavium

[Anonymous Coward]

We can detect the sun directly. We still haven't done that with dark matter. That's why it's called dark matter. Don't make yourself look like a buffoon.

Re:Handwavium

[Xyrus]

Dark matter is still handwavium. The best proof we have for it so far is that if it isn't there the model we use doesn't work.

No, it isn't.

If you're hunting for a bear and you find bear tracks, bear shit, bear claw marks on trees, and everything except for directly observing the bear itself, you don't say the bear is "handwavium" and all of the evidence was really caused by a mutant chicken just because you didn't "see" the bear itself.

Dark matter is exactly the same. We've measured. We've observed. The evidence points to some sort of weakly interacting/non-interacting form of matter. We can't "see" it, but we see the effects it has on everything else. It's the best and simplest explanation we have at the moment.

Now you may not like it. You may think there's a better explanation. But until you put forth your theory with evidence to the contrary that not only explains the current observations but also doesn't break current physics it's simply your unsubstantiated opinion.

Re: Handwavium

[Anonymous Coward]

According to measurement most of the matter in the known universe is dark matter. However we can detect none of it here on earth? So, how did we end up in probably the only known dark matter void?

In the end dark matter is just a correction for an unknown observed occurrence. It just makes the math work. Who knows it may be right, or it might be something entirely diffrent, like another dimension being intertwined with ours and gravitational fields being the only currently observed effect. We just don't know. After all the math for particle physics suggests that there are 23 dimensions, (may be off as I didn't check the value) and even with the evidence science will only accept a few of those. Who knows what is really out there.

Re:Handwavium

[DRJlaw]

Dark matter is still handwavium. The best proof we have for it so far is that if it isn't there the model we use doesn't work.

No, the best proof that we have is gravitational lensing by dark matter halos that have become separated from their associated galaxies after merger events.

Big 'ol concentration of mass with no visible matter = dark matter. The fact that you either weren't aware of the 'best proof' or cynically chose to omit it is irrelevant. It's still observational evidence that is not based upon whether a model does or does not work.

Re: Handwavium

[Anonymous Coward]

Just because pop-sci stories about warp drives say they need a form of exotic matter doesn't mean anything exotic will do. The Alcubierre drive needs an exotic material that creates an energy density below that of the normal vacuum, which is a very specific requirement, and for which dark matter does not apply. The important property of dark matter is that it behaves gravitationally similar to any other matter.

Good job getting modded up for word salad though, many trolls would be envious.

Re:Handwavium

[kevlar_rat]

but really its a bunch of illiterate idiots.

it's

Re:Handwavium

[gtall]

So, your argument is that of the theories physicists can think of, the only one that holds up is dark matter. I wasn't aware physicists have completed their theoretical musings on the Universe, Multiverse, WTFVerse. Did I miss the memo?

Re:Handwavium

[Anonymous Coward]

And yet there are crackpots claiming the Sun is made out of iron instead of hydrogen, and all we see is the upper atmosphere because we've only examined the Sun from a distance. Understanding the observations that make that nonsense are a lot more subtle than what most people know of astronomy observations, yet people are willing to discount that without knowing those details because their gut feelings are okay with what they were told about the Sun. On the other hand, with dark matter, people have gut feelings otherwise, and go with those. In both cases, it is rare to see someone actually try to read up on the details and actually understand why astronomers say one thing or the other, and instead just rationalize why their gut must be right.

Re:Handwavium

[MozeeToby]

What.

No.

We have several empirical results that point to a decoupling of the majority of the mass in a galaxy from it's light emitting matter. The bullet cluster shows us two galaxies colliding, we can see the light from both galaxies coalescing around each other. By measuring gravitational lensing, we can also see that the majority of the mass of those galaxies passing right through each other without interacting.

We know beyond any reasonable doubt that the majority of the mass in the universe does not interact with regular matter, does not produce light, does not interact with light beyond gravitational lensing. That is literally the definition of what dark matter is. There are a handful of viable theories (probably only 2 or 3 likely ones) as to what form that matter takes, but that hardly means we don't have evidence of dark matter existing.

Re:Handwavium

[Buchenskjoll]

But we've never actually seen a bear, so it might as well be a mutant chicken. It's a difference between the known unknown and the unknown unknown.

Re: Handwavium

[Applehu Akbar]

The best argument against wormholes is that if they existed, the aliens would already be here.

On second thought, that might explain the Kardashians.

Re: Handwavium

[Anonymous Coward]

However we can detect none of it here on earth? So, how did we end up in probably the only known dark matter void?

I don't think I've seen anyone propose this as the likely issue. There are still many competing theories on what dark matter is, and many of them point out that detection thresholds are really low. Very few results say, "There is no dark matter candidate X here," are instead of the form, "Candidate X is inconsistent with particle physics observation Y" or "Candidate X has not been detected, but error bars are still big enough to be consistent with quantities need by cosmology."

Re: Handwavium

[Anonymous Coward]

different people will have different ideas on what dark matter actually is. A neutrino was a discreet particle prediction, they could tell you exactly what a neutrino should be and behave before they actually found it. Much like they could tell you about the Higgs-Boson now. Dark matter? Dark matter could be any number of things depending on who you ask. The distinction seems clear.

Re:Handwavium

[MTEK]

I'm not saying it's science... but it's science.

Re: Handwavium

[JoeMerchant]

And then the whole concept is rendered irrelevant, like streaming.

Re:Handwavium

[delt0r]

Yes that is the best theory that matches the data by a mile. You clearly haven't bothered to read ANYTHING other than a few /. summaries about the topic. You are willfully ignorant. You put effort into being ignorant. Then you claim you have some insight.

Re: Handwavium

[Anonymous Coward]

Again, it was ONE of several ideas to solve the anomaly, not the ONLY one.

Re:Handwavium

[Anonymous Coward]

Thank you. I can't believe GGP is at +4. I really don't understand what the fucking problem is for the /. crowd when it comes to dark matter.

Might as well argue that time dilation is handwavium and not being able to accelerate to the speed of light is a liberal conspiracy.

Fucking scientists. What do they know?

Re:Handwavium

[AthanasiusKircher]

The best proof we have for it so far is that if it isn't there the model [which we have created based on our observations of the universe] we use doesn't work.

So... that'd be like... science, then?

THIS.

Not only that, but the entire concept of modern science is predicated on mathematical models of phenomena that can't be observed directly or explained in detail (at least at first).

Our classic history story of the Scientific Revolution often misses this point. We have this vision of people like Copernicus and Kepler and Galileo standing up against ignorant buffoons who refuse to recognize empiricism. But that wasn't it. Scientists had been doing empirical observation for thousands of years. Scientists after Copernicus rapidly (late 1500s) started looking for evidence of the earth's motion -- like stellar parallax and coriolis "forces." They couldn't measure any, and they ultimately weren't measured until the 1800s. That was a major impediment to the heliocentric theory.

But another one was Aristotle's theory of physics, which was wrapped up in detailed explanations of "causes" for everything. And everything in the universe had its "natural place" -- terrestrial matter was assumed to always come to rest, because that's what empirical observation shows us.

If the earth was in some sort of perpetual motion, what caused it? What maintained it? Why didn't the earth fly out of its orbit? Why couldn't we seem to measure it?

The first three questions were answered when Newton's theory of universal gravitation came along. There was this magical unseen force called "gravity," which kept the universe in order.

Many scientists, who believed solidly in empiricism, were highly skeptical of Newton's "occult" forces. (The word "occult" comes from the Latin meaning "hidden" or "unseen," and "occult" phenomena such as unseen forces like magnetism and gravity were associated with "magic" in the 1600s -- not "science" as we understand it.)

Newton responded to his critics by publishing an addendum to later editions of his Principia (usually known as the "General Scholium") which basically said, "Yeah -- those weird invisible 'forces'? I admit they might not be real. But the point is that the math works out, and thus this can be a model for scholarly investigation, even if we can't observe these forces directly or attribute an Aristotelean 'cause' to them."

THAT was really the crux of the Scientific Revolution. Many scientists came to accept Newton's theory, even before the first empirical evidence of heliocentrism (stellar aberration) was measured in the mid-1700s. The math worked, and thus the "model" worked. Even if we couldn't explain all the details, that was now "science."

The history of science after Newton is filled with stories of theories about stuff we couldn't observe directly (electrical charges, atom models, etc.), but which we assumed to exist because they were consistent with the math and the empirical observation. It's also filled with apparent "failures" of invisible things like phlogiston and luminiferous ether.

But those weren't really "failures" of science. They were theories based on rational empirical observation -- they may have lasted a little longer than they should have, but when they were first posited, they were reasonable explanations of what might be going on.

We STILL don't have a complete explanation for how the invisible force of gravity works. But it's well-accepted part of science. Dark matter is no different. Maybe someday it will go the way of phlogiston, but right now it's one of the best explanations around. The fact that dark matter was invented to serve a place in a mathematical explanatory model is the very definition of modern science.

Re: Handwavium

[cyberchondriac]

Then there is no intelligent life out there after all?

Re: Handwavium

[Anonymous Coward]

Thank you. I just can't bring myself to accept dark matter as a viable option. It seems so ad hoc. It is only the best explanation given our current knowledge.

I'm still on the fence, myself. I find it pretty far-fetched to claim that we've made an accurate survey of all the matter in the Universe and come up short. Because we haven't really made such a survey, we've done some limited surveys and then extrapolated from those results. I find it far more likely that our understanding of matter distribution is either flawed, or our observations in that regard are lacking, than it is that we've completely fucked up all physics.
Saying there's "dark matter out there" is a nice way of admitting that we just don't see everything, not that the matter is actually not present.

tl;dr - don't throw the baby out with the bathwater

Re:Handwavium

[ceoyoyo]

Like Neptune!

Actually, like all the planets. And all the stars. We've never actually weighed any of them, but we know their masses because of their gravitational interaction.

Re:Handwavium

[Anonymous Coward]

s/bear/bigfoot/g

Re:Handwavium

[Anonymous Coward]

This is the issue with non experimental science. We haven't found bear tracks. We can see bear tracks in the distance but we can't get to them to actually measure them. And when we look where we are, we don't see any bear tracks at all (which is what the parent is on about). The experimental tests don't stack up with the distant (in time as well as space) observations.

I am also an astophysicist by training but I do get a bit annoyed when people confuse experimental science with observational science.

Re:Handwavium

[tehcyder]

We can detect the sun directly.

You're forgetting which site you're on.

For a lot of people here, the sun has the same level of reality as a girlfriend.

Re:Handwavium

[cyberchondriac]

Maybe I'm nitpicking, (okay, I am) but this analogy assumes you already know what a bear is and have seen bears before, and bears are definitely known to exist. It'd be more like, you see tracks of some sort, claw marks of some sort, scat of some sort, but you don't really know what made them because you've never seen or heard of a bear before, but the evidence is also unlike any creature you've ever seen before.. which leaves room for imagination and educated guesswork.
What if gravity just begins to behave differently on a far larger scale, somewhere in-between the scale of individual stars and whole galaxies, than we expected it would? Dark matter - or rather, evidence thereof- doesn't seem to be observed at any smaller masses than galactic.

Re: Handwavium

[KGIII]

It's odd how quickly people forget that. Hell, that's why the discovery was so important - it helped to give information supporting one of several theories. Did nobody watch the plethora of documentaries on the subject? They were all terrible but they were at least careful to explain it was just one of the theories that had been proposed.

Re:Handwavium

[KGIII]

It seems that the more we learn, the less we know.

Re: Handwavium

[Anonymous Coward]

Remember we have a 2-dimensional picture of a 4-dimensional universe. We don't have all the data from this one angle.

Re:Handwavium

[Anonymous Coward]

Did I miss the memo?

Yes, in the sense you missed the whole basis of science. All of science is the best theory we can think of at the moment. There is always a possibility someone will come along and find a better one. There will always be multiple ways to make the math work, however the more extreme evidence there is, the much harder it will be to find alternatives, especially ones without really weird consequences. But that isn't proof of absolute truth, just as Occam's razor doesn't guarantee you the right answer either.

Re:Handwavium

[thrich81]

"Observational science" has experiments too, they are predictions of future observations. For example when the theory came out that the meteorite killed the dinosaurs, it didn't stop with, "we observed this so this is the explanation". No, it allowed specific predictions such as, "If you look in this stratum in the rocks at the end of the Cretaceous period, you will find anomalous amounts of Iridium, shocked mineral grains, and other evidence of meteorite impact." Also when General Relativity was proposed there were no experiments which could be done to test it, but it did make predictions about observations -- GR predicted the bending of star light past the sun, which was subsequently verified. The ability to make predictions about future observations is very little different from any "experimental science".

Re: Handwavium

[Anonymous Coward]

is just throwing a bunch of shit at the wall and hoping something sticks.

That bit of phrasing describes exactly what the scientific method is. Only a little more....dumb.

Re:Handwavium

[Anonymous Coward]

There is no clear cut separation between observational science and experimental science. There is just a continuum over how much control and variation in parameters a researcher can achieve. Some observational work can vary a lot of parameters by just looking in more places (e.g. a theory that might depend on the temperature of a star is easy to check by looking at many stars of different temperatures). Some experimental work cannot remove certain limitations of the experimental setup, especially some new areas where there may be limited ability to test something (e.g. someone has proposed that the Sun affects radioactive decay... which is not something easily tested in a lab setting in the near term).

Re:Handwavium

[Zalbik]

Wrong. Dark matter is a theory proposed to explain existing observations.

Science is not an absolute "this is how the world works". If you want absolute answers, turn to religion.

Science is an evolving process of "this is our best explanation for how the world works". There is no "proof" in science. Science is observe, measure, theorize, confirm. If you don't like the current theory of dark matter, feel free to propose your own theory that matches existing observations.

Calling it "handwavium" without proposing an alternate theory is antithetical to the scientific process.

Re: Handwavium

[Anonymous Coward]

Reference to whether or not "FTL" is possible in physics almost always means communication of information and movement of mass/energy at faster than light speeds. There are all sorts of ways of thinking you have something moving faster than light that fails to do move information or mass & energy (marques, or the crossing point of a astronomical sized pair of scissors). Quantum entanglement provides no means of moving energy or information at faster than light speeds, even though though there appears to be something happening fast than light between an entangled pair.

Re:Handwavium

[Anonymous Coward]

This is just... wrong. I mean IANAP but intuitively it seems to me that given current understanding and mathematical models using currently accepted theories the majority of the mass of those galaxies is passing right through each other.

Re: Handwavium

[painandgreed]

Currently, dark matter is the leading theory because it explains all the data and it’s also the SIMPLEST explanation.

Which is something to explain to the people who think that dark matter explanation is too strange. We've pretty much past the point where if the solution to the issues we are seeing is not dark matter, the solution is going to be a whole lot weirder. Even with something like MOND, any possible solution to these things by modifying the laws of gravity would make them so complex and strange that nobody has yet come up with even hypothetical laws that might work for our observations.

Re:Handwavium

[Zalbik]

Damnit, now I wish I hadn't commented and just modded your post up instead.

This is a much better and more detailed answer than the one I attempted here

No mod points, but here, have a doughnut:

O

Re:Handwavium

[wonkey_monkey]

Yeah, I think that's pretty much what I said ;)

Re: Handwavium

[Anonymous Coward]

People also forget that the first particle they detected in this search was the neutron, which further helped understanding nuclear physics.

Re:Handwavium

[EvilSS]

Thank you. I can't believe GGP is at +4. I really don't understand what the fucking problem is for the /. crowd when it comes to dark matter.

Might as well argue that time dilation is handwavium and not being able to accelerate to the speed of light is a liberal conspiracy.

Fucking scientists. What do they know?

You must be new here. Everyone on /. is a Nobel laureate in waiting and knows more about physics from reading /. summaries and making quick, 30 second snap judgements than the people who write the papers the summaries are based on.

Re: Handwavium

[suutar]

as I recall, dark matter is required less to explain the universe overall (dark energy gets that role, to explain expansion beyond what we'd predict without it) and more to explain why galaxies can rotate as fast as they do without breaking up, which takes more gravitational force than we can see sources for. So while I totally agree that we haven't really thoroughly surveyed the universe, we have been fairly thorough about some galaxies.

Re: Handwavium

[Anonymous Coward]

What about "Because that's how GOD made it." That's the simplest yet and has similar predictive value.

Re:Handwavium

[Solandri]

I will add that TFS is wrong and that dark matter isn't some "new form of matter." It's called dark matter for the simple reason that it doesn't emit nor reflect sufficient light for us to see. The three forms of matter we're most familiar with - solid, liquid, gas - are all dark matter in the absence of a sufficiently powerful energy source (sunlight). The answer could be as simple as the typical Oort cloud being a lot denser or extending a lot further than we theorize. And we simply can't see that matter because it's so far from its central star.

Re: Handwavium

[Dragonslicer]

So was the hypothesis of the neutrino before it was actually detected. You see, there was this anomaly in the beta decay spectrum and it was hypothesized that the missing energy was carried away by this particle called a neutrino. Decades later the neutrino was actually detected. In what way is dark matter different?

So were Uranus, Neptune, and Pluto, which were all known (or at least strongly supposed) to exist because the orbits of the outer planets weren't quite what they should be if there wasn't another massive body out there.

Re:Handwavium

[Anonymous Coward]

No. It wouldn't be.

"Dark Matter" is the equivalent of "must be magic" from a thousand years ago.

Our models and predictions don't work, so we just assume "must be magic"..I mean "dark matter".

The most reasonable explanation is either a) our models and understanding are wrong or b) we've mismeasured something.

In addition, "dark matter" is just a synonym for "some matter we didn't know about", but the odds are (again) it's just normal matter and nothing exotic/special.

Re: Handwavium

[Anonymous Coward]

But I don't see how Dark Matter is the simplest explanation. Simplest depends on the axioms you begin with. If you begin with the really simple idea that certain physical constants have only been measured in our solar system, and therefore may only apply in our local corner of the galaxy, then the highly speculative notion of Dark Matter vanishes.

Re: Handwavium

[painandgreed]

What about "Because that's how GOD made it." That's the simplest yet and has similar predictive value.

Except that you first have to define god.

Re: Handwavium

[Anonymous Coward]

Simple, if a god is a simple thing. If such a thing exists, which I highly doubt, it is most likely not simple at all. So no, that's actually not the simplest explanation yet. And your view of what constitutes predictive value is ... broken, to be kind.

In short: No. Try again.

Re:Handwavium

[Anonymous Coward]

The three forms of matter we're most familiar with - solid, liquid, gas - are all dark matter in the absence of a sufficiently powerful energy source (sunlight).

They certainly are not dark, they all emit thermal radiation. They also block some amount of light that comes in from behind them.

The first idea astronomers had in response to the idea of missing matter was that there was just a lot of normal matter out there in forms too dark to just see normally. But surveys of microlensing and in the IR set some pretty harsh upper bounds on the amount of such stuff that can be out there. There is definitely stuff out there, and a lot of it, that we can't see, but there would have to be way more even than that to account for what is missing.

Re:Handwavium

[Anonymous Coward]

Your post is completely factually incorrect, and has been proven a few thousand times to be incorrect.

This is the issue with non experimental science. We haven't found bear tracks.

Yes we have, billions of them.

We can see bear tracks in the distance but we can't get to them to actually measure them.

No we don't go there to measure them, we measure them from right here, and we have in many different ways, and all of those ways give the same measurement and agree despite being wildly different in their methods of measuring.

And when we look where we are, we don't see any bear tracks at all (which is what the parent is on about).

No, everywhere we look we see those tracks. Not a single place we have looked did not have those tracks.

The experimental tests don't stack up with the distant (in time as well as space) observations.

There are no experimental tests, so of course that won't stack up with the facts we have observed which do exist.

I am also an astophysicist by training but I do get a bit annoyed when people confuse experimental science with observational science.

Liar

Re: Handwavium

[Anonymous Coward]

f you begin with the really simple idea that certain physical constants have only been measured in our solar system, and therefore may only apply in our local corner of the galaxy, then the highly speculative notion of Dark Matter vanishes.

Atomic and molecular physics has been tested at vast distances due to spectroscopy. Small scale gravitational theory has been tested at many places within our galaxy by observing different systems, from clusters to orbiting compact objects.

Also, the idea is not that the simplest explanation wins, but that the simplest explanation which has the most predictive power and matches observation is considered the best option at a given time. You can't just give a wishy washy sentence and expect it to invalidate a quantitative theory tested by a numerous observations.

Re:Handwavium

[Anonymous Coward]

The most reasonable explanation is either a) our models and understanding are wrong or b) we've mismeasured something.

What people seem to miss over and over again in an effort to validate their own personal feelings about theories they have only a superficial understanding of, is that exactly what you propose here is exactly what astronomers did from the start. They've continued making more and more varied measurements to check that measurements have not been done wrong. They also from the start realized that models were likely wrong, which is why they have spent decades proposing alternative models. Dark matter is a new model, and the front runner of all of the alternatives developed to date. Dark matter theory says exactly that our old model of the universe is wrong, and yet people try to ignore that because it invalidates their feelings on the subject, and so just keep repeating, "But they refuse to say the old models of the universe were wrong..."

Re:Handwavium

[Coren22]

You can feel free to submit your theory of why the majority of the mass in the Bullet Cluster is passing right through and not interacting. It doesn't mean your theory is better though; that the unicorn farts are causing distortions in the light passing by the Bullet Cluster just making it appear that there is mass not in the visible area of the cluster that is bending the light.

Re:Handwavium

[narcc]

That is correct. Observations are not, as many laypersons and modern day positivists believe, completely independent, objective, things. They are necessarily biased by our assumptions and current understanding. As Hanson so succinctly put it: "There is more to seeing than meets the eyeball." More clearly "There is a sense, then, in which seeing is a ‘theory-laden’ undertaking. Observation of x is shaped by prior knowledge of x."

Brining this back to the topic:

Quine, rather embarrassingly, suggested that we follow the simplest approach that challenges as few of our preexisting beliefs as possible when confronted with competing theories resulting from failed predictions from our existing theoretical commitments, noting that observation and evidence aren't always sufficient for settling those sort of scientific disputes. (Kuhn talked about this in terms of theories from different paradigms being incommensurable. A bit stronger, even suggesting that "proponents of competing paradigms practice their trade in different worlds".)

I think this leads to a danger, better articulated by Popper, that a lot of users here seem to have a strong gut-feeling about:

Some genuinely testable theories, when found to be false, are still upheld by their admirers -- for example by introducing ad hock some auxiliary assumption, or by re-interpreting the theory ad hock in such a was that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status

There's a dramatic image here, with ad hoc assumptions slowly rotting away old ideas until some new thing comes along to bury the corpse. At least this feels more rational that Plancks version: "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it". It would be nice to see the ideas rot before the scientists.

Re:Handwavium

[wonkey_monkey]

But we've never actually seen a bear, so it might as well be a mutant chicken.

Presumably we've never seen this "mutatnt chicken" thing either. So why don't we just call whatever we find a bear, since it will probably have the properties we're expecting (makes bear tracks, leaves bear poop);.

Re:Handwavium

[techno-vampire]

Actually, no. Nobody predicted the anomalous amounts of Iridium or other evidence of a meteorite impact. They were observed, and a theory was constructed from those observations that the timing was right to explain what happened to the dinosaurs.

Re: Handwavium

[Anonymous Coward]

Except for one *tiny* little problem . "Because that's how GOD made it." has absolutely no predictive value.

Re:Handwavium

[Anonymous Coward]

Actually, it's a bit of both. The anomalous amounts of iridum, etc. was one of the clues that led to the hypothesis of the asteroid impact.
The impact theory *also* predicted that the iridium would be found (mostly) everywhere, as well as explaining and predicting *other* things discovered.

When the iridum layer was subsequently found in more and more places as people started looking for it, it strongly supported the asteroid impact theory. The eventual discovery of the remnants of the impact crater itself, and physical models of an impact that would generate such a crater also generating the iridium layer, and other evidence, has fairly solidly cemented that theory as fact.

Re:Handwavium

[Anonymous Coward]

"So why don't we just call whatever we find a bear"

Because then everyone would be looking for bears, and might not ever find/notice the mutant chicken. Same thing with Dark Matter. Same thing with witches. People used to hunt for witches because someone claimed that some phenomenon X was the work of witches. So they spent all their time looking for witches and completely missed the actual cause of said phenomenon X.

Re:Handwavium

[John Da' Baddest]

Just like Darwinian Evolution. "Some How It (just) Happened."

Re:Handwavium

[strikethree]

The evidence points to some sort of weakly interacting/non-interacting form of matter.

The hypothesis of Dark Matter can not be taken seriously until there is some way to falsify it.

But until you put forth your theory with evidence to the contrary that not only explains the current observations but also doesn't break current physics it's simply your unsubstantiated opinion.

Dark Matter in fact DOES break current physics. There is no theory of matter that exists that can explain a mass that does not interact with anything and yet creates gravity.

Th universe is pure energy. "Condensing" this energy creates matter, which creates space-time. I would argue that our understanding of space-time is insufficient, not that our understanding of matter is insufficient.

Does this imply modifications to our understanding of gravity? Yes. I would argue that gravity is not a simple homogeneous basic force, rather it is merely an effect of time and space interacting with matter in ways that we do not fully understand.

CAPTCHA is moonlit: Perhaps light, which is energy minus mass (so not pure uncondensed energy) alters the quality of space-time in such a way as to appear to "slow down".

Re:Handwavium

[mattack2]

Dark matter is still handwavium. The best proof we have for it so far is that if it isn't there the model we use doesn't work.

Then come up with a better model that fits all of the observed data. (You'll probably win a Nobel Prize.)

That's how science works.

Re: Handwavium

[tnk1]

This is true. No matter how many times I see spooky action at a distance explained to not be FTL communication method, someone still thinks it can be a FTL communication method.

That said, FTL is not only movement of information at FTL speeds, it is movement of information at speeds which are FTL relative to other points. So yes, if there was a way to warp space-time so that a normal light speed EM wave simply had a shorter distance to go, that's still FTL communication.

Of course, since no one has demonstrated that warping space time is possible in that manner, and wormholes (while still not ruled out) appear to require a sort of exotic matter that is unlikely to exist, FTL is very much a goal with fiction wrapped around it, rather than science.

Re: Handwavium

[Anonymous Coward]

Also, the idea is not that the simplest explanation wins, but that the simplest explanation which has the most predictive power and matches observation is considered the best option at a given time. You can't just give a wishy washy sentence and expect it to invalidate a quantitative theory tested by a numerous observations.

Good points (OP here), but I'm really curious, is it a strong enough theory to make falsifiable predictions? I am really interested in knowing more, and these articles never seem to get into the details very far. What the article seems to be saying is that Dark Matter cannot be directly measured, and we simply have a quantity that varies unpredictably from one region to another. How do you make falsifiable predictions about something that you can't directly measure, which exists in unpredictably different concentrations depending on something unknown? Or does the article just not explain things in enough detail?

Re: Handwavium

[tnk1]

You mean traversable wormholes. Wormholes can certainly still exist without aliens being here if they convert any aliens to random energy when the aliens attempt to access them.

Re: Handwavium

[Anonymous Coward]

The two competing ideas are that either it is a separate substance, dark matter, that can move around on its own independently, or that there is some variation in the law of gravity. The latter would require that "dark matter" properties follow visible matter everywhere, since it gravity is still from normal matter but just with a variation in how it behaves at long distances. More and more evidence that there are examples of dark matter properties not staying attached to the visible matter potentially falsifies that these phenomena are the result of properties of normal matter we just don't understand. On the other end, predictions of specific dark matter models like cold and warm dark matter did predict collisions should be able to remove dark matter from a galaxy in a way not associated with the movement of normal matter. Those could have been falsified by looking at enough galactic collisions and not seeing what they expected, setting a bound on how easily the dark matter effects could be separated from normal matter.

Re:Handwavium

[Anonymous Coward]

Except astronomers and physicists collectively don't spend all of their time looking for dark matter. There are whole research teams at universities examining alternative gravity theories, both working on existing ones and looking for new ones. They aren't even close to considered fringe, and get quite a lot of attention from the community. But even they are starting to complain that their theories can't work as well as dark matter and they are dealing with their own arbitrary fitting parameters.

Re: Handwavium

[tnk1]

Realistically, wormholes or not, even a civilization limited to light speed travel should have been able to colonize or visit most of the galaxy in just a few million years with robotic exploration. So, it is looking like there is either no one else out there, or just as likely, there is some sort of barrier to intelligent civilizations being able to launch such an effort like colonization or robotic exploration.

Obviously, this all assumes that someone would have done all of this first. We might be either the first civilization at this point, or at the very least, a member of the "first wave" of civilizations where the other civilizations do exist, but their evidence has not yet arrived here. That scenario is just as likely as any other solution, but it is less useful because then we have nothing yet to look for in order to confirm our theory, so we tend to assume that we're not a member of "the First Ones".

There is also the idea that there may be a "Great Filter", which is some sort of event or situation that all intelligent species run into before they can do interstellar exploration. It could be something like nuclear holocaust or self-destruction being inevitable, or as simple as running out of available energy to be able to maintain high technology before they could start the program. Or some combination.

Nuclear war, unfortunately, is probably inevitable. It is a more distant threat than it used to be, but the weapons are all still there, and even pariah states like North Korea have working weapons. While those states remain somewhat rational, we're probably fine, but the stakes are pretty high.

Another possibility is simple overheating. Here I'm not exactly talking about Global Warming as caused by carbon emissions, but actual generation of heat by releasing it through energy production as waste heat. Solar energy doesn't help us with this because increased capture of solar radiation will increase waste heat on Earth. Eventually, carbon dioxide or not, we might simply add more waste heat to the planet than the Earth can actually radiate out into space. In that sense, I am very much a believer in AGW, although that scenario is probably more remote in time than a CO2 based greenhouse effect. Eventually, the Earth will need a giant heat sink if we want modern civilization for ever increasing numbers of people.

Re:Handwavium

[techno-vampire]

You are, of course, correct. The point I was trying to make is that the idea of an asteroid impact came from the original discovery of the Iridium layer in (I think) Calabria, and later discoveries of similar deposits in other locations confirmed it. The OP made it sound as though the discoveries confirmed an existing theory, rather than gave us a reason to create a new one.

Re: Handwavium

[tnk1]

Actually only 23% of the universe is Dark Matter. 70+% of the Universe is Dark Energy, which is something believed to not be directly related to Dark Matter except in that we have labeled both of them as "dark".

The (likely) reasons we don't detect it on Earth are:

1. It is believed to clump in specific areas of galaxies. The density of dark matter in "our" part of the galaxy is extremely low. This is borne out by observations of other galaxies.
2. It is supposed to be very difficult to detect to begin with. We've only actually detected it because it causes gravitational effects on large scales. While that sounds "too convenient" if you don't believe it exists, this doesn't eliminate it. As someone pointed out previously, neutrinos are extremely difficult to detect even though we're showered with them constantly because they are just so weakly interacting with other matter.

Re: Handwavium

[tnk1]

As someone who does believe in God, I disagree about how they are similar.

Much of what we attribute to God must be taken on faith alone and was revealed, not discovered. It is not scientific at all in the sense that it can be tested.

Dark matter is a hypothesis that has observations where it makes as much, if not more sense than any of the other scenarios. I think everyone knows that Dark Matter isn't a full fledged theory yet, but there's nothing else with predictive value either, so that doesn't disqualify it from investigation. It does, however, explain observations adequately, which is a real test of a useful hypothesis.

 

Re: Handwavium

[irrational_design]

"or just as likely, there is some sort of barrier to intelligent civilizations being able to launch such an effort like colonization or robotic exploration." That barrier is called "politicians". You could also include the rest of the non-intelligent members of civilizations, but mostly politicians. Since robotic explorers haven't reached our solar system, this is merely proof that politicians are universal.

Re: Handwavium

[sexconker]

Entanglement does not enable instantaneous communication over distance.
Entanglement does not involve FTL transfer of information.
Entanglement does not violate causality.

Re: Handwavium

[sexconker]

How is dark matter simpler than the idea that we simply aren't able to observe the entire universe, and thus can't even begin to speculate as to how much mass we should be seeing?

Re:Handwavium

[thrich81]

OP here. And you are, of course, correct. My understanding is that the discovery of the first Iridium anomaly led to the Impact Hypothesis, which then led to the further predictions including worldwide Iridium deposits in the Cretaceous boundary. I was lucky enough to see Walter Alvarez talk about it at the university here in the early 90's. I was writing pretty fast this morning and hoped no one would call me on it:), guess I'll be more careful next time! Hopefully this inaccuracy didn't detract form my point that "observational" sciences make testable predictions, too and are not inferior to the "experimental" sciences.

Re:Handwavium

[Anonymous Coward]

The best proof we have for it so far is that if it isn't there the model [which we have created based on our observations of the universe] we use doesn't work.

So... that'd be like... science, then?

Exactly. The model we've created based on our observations of the universe doesn't match our observations of the universe. So the model must be right and there must be another type of matter that makes it right. That's science, kids.

Re: Handwavium

[avgjoe62]

I tend to think we have just reached the Great Filter. I can see our civilization saying, "Yeah, we'll launch that Interstellar probe as soon as we're done binge watching Breaking Bad.

Re: Handwavium

[truck_soccer]

crud. I fell victim to a common misunderstanding about spooky action. Quantum stuff is hard and it hurts my brain.

Re: Handwavium

[truck_soccer]

Hi, I am dumb.

Re:Handwavium

[Anonymous Coward]

Lol, love the bear analogy !

Re: Handwavium

[Anonymous Coward]

Welcome to inductive logic, i.e. science 101. There is always some possibility that a theory that has previously held up to tests gets proven wrong the next day with new data, because we cannot observe all of the universe and time.

Re:Handwavium

[Anonymous Coward]

Umm, what part do you not understand about astronomers creating a new model and throwing out the old? Lets FTFY:

The old model we've created based on our old observations of the universe doesn't match our new observations of the universe. So the old model must be wrong and we propose a new model that there must be another type of matter and this matches the new and even newer observations

Re: Handwavium

[Anonymous Coward]

The assumption that FTL is possible and we just have to work out how is not backed by anything more rigorous than Star Trek.

And you missed the point!

The point was not about speculating whether FTL was possible but that the "Exotic Matter" speculated to make such things work is a real thing.

Reading comprehension is not your strong suit.

Re: Handwavium

[Anonymous Coward]

Entanglement does not enable instantaneous communication over distance.
Entanglement does not involve FTL transfer of information.
Entanglement does not violate causality.

You also missed the point. At no point was Entanglement or FTL communication mentioned, rather the speculation was about Exotic matter being indicated to exist if the "Non Baryonic matter" was the cause of the observed movements of galaxies and galaxy clusters, it would have to exist right?!?! It has been repeatedly said that to make a traversable wormhole you would need "Exotic Matter" which has been defined as a type of non-baryonic matter..

You guys need to work on your reading comprehension.. you get stuck on an argument idea and miss a lot of stuff , like the actual point of what is being said!

Re: Handwavium

[Anonymous Coward]

Speaking of needing to work on reading comprehension:

It has been repeatedly said that to make a traversable wormhole you would need "Exotic Matter" which has been defined as a type of non-baryonic matter..

Wormholes and warp drive proposals don't just require non-baryonic matter, but matter with negative mass density. Baryonic matter all has positive mass density, but not all proposed non-baryonic matter has negative mass density, and dark matter used in dark matter theories certainly does not.

Baryons are just one category of known particles out of many known particles (electrons are non-baryonic...), and there are a vastly larger number of proposed non-baryon particles, almost all of which do not have negative mass density. Also, the expression exotic in particle physics usually just means some particular property is different, not that any given property is exactly the same as something else that is exotic. So exotic matter is a broad category of theoretical materials that can be completely different from each other.

Your reasoning is on par with someone saying they need an exotic non-metric bolt, and assuming they can buy it any given store that sells inch sized bolts, when they really needed something more exotic like an acme screw.

Re: Handwavium

[Anonymous Coward]

that the "Exotic Matter" speculated to make such things work is a real thing.

Nothing here suggests that and matter of the necessary properties has never been seen before or ever suggested to exist...

Re:Handwavium

[Anonymous Coward]

This has historically been the biggest contender other than Dark Matter to explain the observations. However, as TFA notes, the evidence does not point that way. There are multiple independent lines of evidence for Dark Matter, please -- pardon my invective -- shut the fuck up and educate yourself before continuing to post in this or any related discussion.

Modified gravity theories have to contort in contradictory ways to explain even the simple gravitational effects, and they were killed stone dead with the CMBR and these latest Hubble findings. Anyone with any doubt on the matter is welcome to posit a new theory but they have a lot of observations to account for.

Re: Handwavium

[Bengie]

There is still some research going on that some of the leading names in quantum physics are hopeful with. They take two entangled photons, A and B, send A at another sensor a long distance away, then entangle B with C, where C is known. Because when you measure an entangled photon, the other photon becomes the opposite. So when C is entangled with B, then B because anti-C, but because B is also entangled with A, A because anti-B, which is the same as C. But in this process, C is randomized and loses its original information.

I guess preliminary tests show this to probably work, but they need more samples and it is very hard to do.

Re: Handwavium

[Bengie]

The alternative to Dark Matter is crazier than Dark Matter. The lesser of two evils if you will. There is a lot of mounting evidence. After decades of work, someone finally got MOND to work, but it required a matter that has not been detected and is not the same as any other known matter. They reinvented Dark Matter.

Re: Handwavium

[Anonymous Coward]

Speaking of needing to work on reading comprehension:

It has been repeatedly said that to make a traversable wormhole you would need "Exotic Matter" which has been defined as a type of non-baryonic matter..

Wormholes and warp drive proposals don't just require non-baryonic matter, but matter with negative mass density. Baryonic matter all has positive mass density, but not all proposed non-baryonic matter has negative mass density, and dark matter used in dark matter theories certainly does not.

Baryons are just one category of known particles out of many known particles (electrons are non-baryonic...), and there are a vastly larger number of proposed non-baryon particles, almost all of which do not have negative mass density. Also, the expression exotic in particle physics usually just means some particular property is different, not that any given property is exactly the same as something else that is exotic. So exotic matter is a broad category of theoretical materials that can be completely different from each other.

Your reasoning is on par with someone saying they need an exotic non-metric bolt, and assuming they can buy it any given store that sells inch sized bolts, when they really needed something more exotic like an acme screw.

Good answer to a point. You are reading in where you say that I made any assumption that non-baryonic exotic matter with negative mass density is easy to come by. All I pointed out is that non-baryonic matter exists.. that is not to say that you can just go down to fry's and buys some. If non-baryonic exotic matter exists in the universe then **** LOGICAL LEAP**** non-baryonic matter with negative mass density **MAY** be a real thing.

You get all these basement dwellers that love to point out how everybody else is wrong and that they are right.. and they quote the theses of their high school physics textbooks when it is non germane to the conversation. This is not a failing of physics, this is a failing of the particular basement dweller. This is why these particular basement dwellers have not won a nobel prize or been published. They have not been published because they have not produced anything and it burns them, they feel like nobody listens to them and that they are some sort of "undiscovered genius". It is ridiculous, all I was doing was pointing out that this finding does not rule out non-baryonic matter of the type that might be used to construct traversable wormholes or FTL style singularities that ***COULD*** be possible not that are possible. This is not going to stop the idiotic variety of nerds from popping out of the woodwork and cyber bullying, because if they did that shit in real life anyone.. your little sister would stick their head in the toilet and flush. It is funny how they are probably standing in front of a mirror practicing their boxing moves and imagining that they are right, because they quoted a single quote from a science textbook that is , in the context of the conversation, a non-sequitur.

Ridiculous how fucked up some people are on here!

Re: Handwavium

[Bengie]

Dark Matter is the simplest because if it is not real, then we have to ditch all of current physics. It means Relativity is wrong, and not just a little wrong, but incredibly wrong. And that's just the tip of the iceburg. It also implies that all of our measurements are wrong in the first place. Can you see the logical implication of assuming our measurements of the rotations are correct, but everything else is wrong? It really is a can of worms. Of course nothing is 100%, it's just the current best.

Re:Handwavium

[Bengie]

Depends on your definition of "directly". Have you touched the Sun? Ohh, you're just using instruments and measuring results, just like Dark Matter. We only have indirect evidence that the Sun exists.

Re: Handwavium

[Spinalcold]

And there are very specific parameters for Dark Matter as well, it must interact gravitationally, it must not interact with EM. All the models I know of also have parameters on mass. Thing is, this isn't JUST a experimental science, there are theorists who are trying to fit Dark Matter into The Standard Model. The Standard Model is built upon symmetries, so if you just add in DM it would break it, it needs to be added in specific ways and thus has to have specific properties. The last hundred years of physics has been very heavily leaning towards mathematics (I mean more so than before), and the past 50 years of particle physics has been heavily reliant upon symmetries, and you know what? It's payed off wonderfully! Just by working out symmetries we have discovered the Higgs, 3 generations of particles, neutrino flavor mixing, and lots of others I don't even know about.

Besides, the neutrino hypothesis was wrong, it thought neutrino's were massless. They are not.

Re: Handwavium

[Anonymous Coward]

Really? Because I was reading this thread wondering why all these Star Trek nerds are talking about warp drive when the article is about dark matter. It's annoying when lay people read a couple wikipedias about warp drive and the broad term exotic matter and start commenting on dark matter articles as if vauge familiarity with concepts gives one the place the start hypothesizing theories of the universe. Leave it to the professionals. I want to hear from them, not you.

Re: Handwavium

[Anonymous Coward]

All I pointed out is that non-baryonic matter exists.. that is not to say that you can just go down to fry's and buys some. If non-baryonic exotic matter exists in the universe then **** LOGICAL LEAP**** non-baryonic matter with negative mass density **MAY** be a real thing.

Non-baryonic matter has been known to exist for over a century, i.e. the electron. Most particles known about for many decades now are non-baryonic... I don't think you even know what non-baryonic means and why stuff like this is no more evidence that negative mass exists. Non-baryonic just means particles not made out of three quarks.

Re: Handwavium

[Anonymous Coward]

Do you also get excited about the possibilities of warp drive whenever there is a news article about halogens and non-metallic elements, because non-baryonic matter also happens to be non-metallic? After all, if non-metallic matter exists, then it is possible that any kind of exotic matter exists too right?

Re: Handwavium

[lucien86]

"The assumption that FTL is possible and we just have to work out how is not backed by anything more rigorous than Star Trek."

So that's a lot more proof than there is for the version of the FTL described by General Relativity. If the general relativity version is correct then 'wormholes' theoretically allow unlimited travel anywhere in space and maybe even in time. However this is only because the whole universe is flexible and bendable and essentially completely unstable. Among other things this general relativity version is also almost completely incompatible with black holes which it predicts should collapse in on themselves and become externally massless.

Any real scientific analysis leads straight to a simple absolute frame FTL model universe. That makes FTL travel theoretically possible, but also makes long range wormholes impossible because the universe doesn't fold like a pretzel. It also makes time travel impossible because there is only one reality and time as dimension doesn't exist - except at quantum scales...

Re: Handwavium

[lucien86]

Of course we can actually create exotic matter. - The quark gluon plasmas created briefly by particle accelerators like the LHC are effectively forms of exotic matter...
If dark matter does have negative mass then it is probably tachyonic, which would also explain why it does not interact except through gravity.. This would also offer a neat explanation for the observed imbalance between matter and antimatter because +n + -n = 0..

Re: Handwavium

[Anonymous Coward]

The quark gluon plasmas created briefly by particle accelerators like the LHC are effectively forms of exotic matter.

But still exotic in a way that is of no relevant to what is needed for GR theories about warp drives and wormholes.

If dark matter does have negative mass then it is probably tachyonic, which would also explain why it does not interact except through gravity..

If dark matter has negative mass, then it wouldn't match the observations and evidence that suggest the existence of dark matter. In other words, it wouldn't be dark matter, but something else unconnected to the evidence of dark matter, and hence probably completely baseless short of some radically different theory.

This would also offer a neat explanation for the observed imbalance between matter and antimatter because +n + -n = 0..

That solves nothing in the sense that we know of many reactions that produce equal amounts of matter and antimatter and have trouble accounting for any imbalance even in that. You would still have to deal with the imbalance between matter-antimatter and tachyons and whatever their time symmetric particles would be.

Re: Handwavium

[Anonymous Coward]

Apparently you have never heard of projective geometry or coordinate freedom.

Re: Handwavium

[Areyoukiddingme]

...but actual generation of heat by releasing it through energy production as waste heat. Solar energy doesn't help us with this because increased capture of solar radiation will increase waste heat on Earth.

Only if we're foolish enough to allow solar power satellites to actually happen. If all of the solar panels we use are on Earth, then this is not a problem at all. An earthly solar panel only converts energy. It doesn't create it or generate it out of nothing. The incoming energy is already there, in the sunlight. You actually end up with less heat at the point of collection than you otherwise would when a photovoltaic panel converts some of the energy in the photons of sunlight into electrons and ships it out over a wire.

Photovoltaics (commonly understood to be "solar power"), windmills, and dams are all the same type of thing. They're energy converters, not generators, and they're all converting solar energy. Photovoltaics do it directly from photons. Windmills and dams do it by squeezing the energy out of the motion of fluids like water and air. Fluids that are kept in motion by solar energy. None of them result in extra waste heat. They result in the same amount of waste heat that would have happened anyway, except instead, they get some useful work done first. The heat that didn't happen when a photovoltaic panel caught some sunlight instead happens when an electric motor uses that energy. It's the same amount of heat, just in a different place, and with batteries involved, at a different time.

Speaking of batteries... Batteries are 85% to 90% efficient. That 10% to 15% inefficiency? Heat. So a 22% efficient solar panel converts 22% of the energy in the sunlight hitting it into electrons. The other 78% is heat. If the solar panel wasn't there, it would have been 100% heat. The electrons created by the solar panel flow down a wire to a battery. The battery sucks them up, but it misses some, and produces some heat. A battery being charged is warmer than one that isn't being charged. Then when somebody wants power, they flip a switch, the battery gives up its electrons, and a motor uses them to make itself spin. The spinning happens in spite of friction, but friction extracts its price, and you get heat. The 90% of 22% of the heat that didn't happen underneath the solar panel is given up by the motor. All heat accounted for and nothing extra created. (Ok, not all heat accounted for. I left out wire heat. Wires aren't 100% efficient either, so they heat up too when the solar panel puts electrons through them. But you get the idea.)

Orbital solar power, on the other hand, is a seriously bad idea. It takes heat that was going to miss Earth and aims it at the planet. If we did too much of that, we could literally cook ourselves. Fortunately we're mostly unable to do it at all, and it's silly anyway when there's all this free sunlight around that's already hitting us.

Re: Handwavium

[brantondaveperson]

We don’t have direct measurement of it. We just have a phenomenon

Well, since gravity and mass are pretty much the same thing, and we've observed the effect of the gravity, I'd say that we have observed the mass. Further, since we don't believe that mass can exist without matter, then we've observed the matter too. We don't know what it us, sure, but it's certainly something.

Re: Handwavium

[s1sfx]

It isn't an explanation, just a conceptual place holder. Like a Joker in a card game. Or an X in a maths equation.

Re: Handwavium

[Anonymous Coward]

I think dark matter is the leading theory by far, but even then I think you're making assumptions, possibly without realizing, and I think such things should be kept up front.

Well, since gravity and mass are pretty much the same thing, and we've observed the effect of the gravity, I'd say that we have observed the mass

No, gravity depends on mass & energy (and actually a few other things under GR, like momentum and pressure plus flux of those things). The exact relationship is open to question when one is considering the possibility of the theory of gravity to be wrong. Seeing gravity is not the same as just seeing mass, as you need to know the exact relationship between mass distribution and the influence of gravity, which is something many physicists research groups are studying to double check there isn't another relationship that works better.

Further, since we don't believe that mass can exist without matter, then we've observed the matter too.

Depends on what you are going to call matter, because GR just cares about energy density, whether it comes from the mass of matter or some other source.

Dark matter can explain several different observed effects in astrophysics on several different scales, something alternative gravity theories cannot do so far. But that is not the same as saying we're certain something is there, even if confident in some senses.

Re: Handwavium

[Theovon]

"GOD made it" is never a simpler explanation for two reasons:
1. This may invoke the requirement to explain God.
2. It's not really an explanation, in the sense that it's not actually a model of the phenomenon. You can't test this explanation, and you have no hope of using it for engineering.

Re: Handwavium

[cyberchondriac]

Actually I was referring to the parent's line, "..that might explain the Kardashians", but thanks.

Re:Handwavium

[cyberchondriac]

This has historically been the biggest contender other than Dark Matter to explain the observations. However, as TFA notes, the evidence does not point that way. There are multiple independent lines of evidence for Dark Matter, please -- pardon my invective -- shut the fuck up and educate yourself before continuing to post in this or any related discussion.

Oh yes, with your level of professionalism, which is to smugly point to Wikipedia and tell other people rudely to shut the fuck up, I'll certainly disallow my freedom of speech in the future on any matter which your exalted grace disagrees with. Or, y'know, how about, fuck you?
Science is an open ended process, not dogma, and in particular there is still so much unknown about "dark matter" that it's still a valid point of discussion, current evidence notwithstanding, whether you like it or not. So bully and insult all you want, you only reveal yourself to be a hateful, angry condescending little man.

Re: Handwavium

[beastofburdon]

The Electric Universe theory explains a very large portion of these observations along with some of the problems we have with the current model of the sun. It also makes far more sense and does not require any hand wavy dark matter. Yet the majority of astrophysicists refuse to even breath the name, much less test the theory. It wreaks of groupthink.

Re: Handwavium

[beastofburdon]

And that is why they cling to dark matter and dark energy like a religious zealot clings to his belief in god. It is just human nature that when we feel our beliefs being challenged on such a large scale our minds subconsciously use every logical fallacy to convince ourselves that our original beliefs are right. When this effect is expanded to a large community who share the same beliefs those beliefs start to be protected by threats to careers and ostracization.

This makes real advancement extremely hard when there is an established model which is flawed. Any challenge to that flawed model is met with threats, ostracization, character assassination, and censorship. I think that this may well be where we are at now. We have a seriously flawed model which can't even explain the observations within our own solar system, particularly the sun, that we have been trying to force upon the universe while ignoring huge blatant flaws. All the while putting our fingers in our ears and covering our eyes to all the data which contradicts the theory. The sad part is that nothing will change until the current leaders in the field grow old and die.

Re:Handwavium

[beastofburdon]

And yet there are crackpots claiming the Sun is made out of iron instead of hydrogen

I would really love to see an explanation of how a star forms which leaves the center of it being hydrogen. Then how after that star miraculously forms out of just the light gases from the accretion disk that the planets are made almost entirely of the heavier elements. This idea seems rather odd to me. Are you saying that somehow gravity works differently during the formation of a star? It would have to in order for it to consist almost completely of hydrogen. If there is enough gravity in the system to pull in the lightest element how in the hell are the heavier elements escaping this only to be pulled together to make planets? And somehow in this theory the few heavy elements that managed to make it there are close to the surface while that extremely light hydrogen was pulled down to be the core.

Face the facts, we don't know a damn thing about stars and our standard models of them can be disproven with minor questioning.

Re:Handwavium

[beastofburdon]

Or you know, you could admit that there is a massive flaw in your theory, since the galaxies that we can observe couldn't exist in it, and go back to examine the underpinnings of that theory instead of claiming that everything so far must be right and then slapping the handwavium undetectable matter into the theory.

Re:Handwavium

[beastofburdon]

Yup, just religion quietly slipped into a scientific theory.

Re:Handwavium

[beastofburdon]

Here's a much better analogy for this situation.

A man who was born and raised in the city, never been in the woods, and never seen a jackalope goes jackalope hunting. He is certain that the jackalope exists because he has seen pictures of it on the internet. As he walks through the woods he sees a small pile of shit on top of the fallen leaves. Now that pile of shit is made up of small pieces that are almost shaped like balls, just a little oblong. The hunter thinks back to the picture of the jackalope an remembers that it looks a lot like a rabbit, and he has seen rabbit shit at the fair and it is about the same size, but less oblong. Well, of course the jackalope would have slightly different shit, it is a different animal after all, so he is certain that he is hot on the trail of the mighty jackalope.

As the hunter continued to follow the signs of his prey he did run into a group whitetail deer, none of which had any antlers, but he never did find his jackalope. When he finally gave up and returned to his home city he told his friend about his hunt for the great jackalope. His friend told him that there was no such thing as a jackalope, it was just photoshoped picture he found on the internet, and that the shit he found was from the group of whitetail doe's that he encountered. Upon hearing this the mighty hunter flew into a rage. He kicked his friend out of his house and has refused to talk to him ever since.

Re:Handwavium

[beastofburdon]

You forgot ignorant and closed-minded.

Re:Handwavium

[beastofburdon]

What exactly tells us that they are colliding?
Is it that they are overlapping?
The last I checked we didn't have the technology, or the multiple viewpoints, needed to determine exactly how far away the two galaxies are. In other words, we have no proof whatsoever that they are colliding at all, much less proof from it that dark matter exists.

Re:Handwavium

[beastofburdon]

It would be nice to see the ideas rot before the scientists.

Yes it truly would, but that goes directly against human nature.
As individuals and as groups we tend to be blind to our own biases, and it gets worse the larger the group gets.

It means

[Anonymous Coward]

... what we see of galaxies and the Universe in general simply doesn't match up to our predictions

So maybe we're in a small fold, a dark corner of the universe and can see only 1% of it? That may mean the laws of gravity or relativity were broken to form the whole universe.

Re:It means

[Anonymous Coward]

... what we see of galaxies and the Universe in general simply doesn't match up to our predictions

So maybe we're in a small fold, a dark corner of the universe and can see only 1% of it? That may mean the laws of gravity or relativity were broken to form the whole universe.

No, this is a common misconception. What we observe is that when looking at a specific region of space, we see interactions occur which are not fully explained by the matter which exists within that space.

Here's an analogy- Say we have a house (the Universe), and we're standing inside a single room within that house. We know how warm the room should be if it's empty, and how much heat is produced by a person who stands in the room. We can see three people standing in the room, but our temperature reading shows that there really ought to be a fourth person to account for all the heat. So then we go to other rooms, which have other people in them, and in each case we also observe that there's more heat than there ought to be.
We aren't claiming to have knowledge of the entire house, just the rooms we've looked at, but what we see is consistent across all the rooms.
Of course it's not a perfect analogy by a long shot, but it illustrates that the issue is not that the 'dark matter' exists in a region of space we haven't looked at yet.

Re:It means

[beastofburdon]

And later a reporter managed to get the number to the house in question and gave it a call.

Reporter: Hello, our scientists have been observing your house for a while now and it appears that the rooms are warmer than they should be for the number of people in them.

Man in House: How can your race have the technology to look at a house outside your solar system and still be too stupid to realize that there is a heater in the basement.

Gravity leak from other dimensions?

[Mostly a lurker]

I am sure the possibility must have been explored that "dark matter" and "dark energy" originate in other dimensions. Is there clear evidence to discount this?

Re:Gravity leak from other dimensions?

[Anonymous Coward]

You mean apart from the complete lack of evidence of other dimensions?

Re:Gravity leak from other dimensions?

[Anonymous Coward]

You mean apart from the complete lack of evidence of other dimensions?

As we stand in the middle of a conversation about matter we've conveniently labeled as dark** and called it law, perhaps the Pot shouldn't speak so arrogantly to the Kettle.

(** miscellaneous shit we made up to fill a void. Catchy name, right?)

Re:Gravity leak from other dimensions?

[nightcats]

That actually makes some intuitive sense. My only problem with "dark matter" is the term itself: I saw recently in Nature (the science mag) that one astronomer had proposed the term "transparent matter," which I like a lot better.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

But it is not transparent. It is however dark in the sense that it does not interact electromagnetically.

Re:Gravity leak from other dimensions?

[nedlohs]

Some "miscellaneous shit we made up to fill a void" that explains the areas in which a theory that has been shown robust in many other areas doesn't work in is not the same as making something up that doesn't fill a void, doesn't make the existing theory work in some area it wasn't before, and doesn't offer any predictions.

Re:Gravity leak from other dimensions?

[nedlohs]

If it does not interact electromagnetically it must be transparent.

Re:Gravity leak from other dimensions?

[Black Parrot]

That's my favorite explanation.

Note that unlike Ockham, I think we should go with the most fun of the hypotheses that haven't been ruled out, rather than the simplest.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

Or just call it Fields of Anomalous Gravity.

Re:Gravity leak from other dimensions?

[Sique]

Actually no. All baryonic matter we know of, transparent and intransparent, interacts with electromagnetic waves. All transparent baryonic matter for instance comes with a specific refractive index describing how it reduces the speed of light crossing it. The refractive index of dark matter is 1, e.g. it has no influence on the speed of light. For light, dark matter just isn't there, quite different than transparent baryonic matter.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

One possibility is it does not interact electromagnetically, but it is important to note that it can still have some EM interactions, they just must be very weak. There are several proposed models that involve EM interactions and searches for those. These can involve collisions with very low cross-section or very rare decays, etc., that then involve searches for annihilation signatures in gamma rays or light pulses within certain kinds of particle detectors.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

http://home.cern/about/physics/extra-dimensions-gravitons-and-tiny-black-holes

Re:Gravity leak from other dimensions?

[Anonymous Coward]

That actually makes some intuitive sense. My only problem with "dark matter" is the term itself: I saw recently in Nature (the science mag) that one astronomer had proposed the term "transparent matter," which I like a lot better.

Dude, dark matter is way cooler than "transparent" matter. That's why we have dark force, not "transparent" force.

Re:Gravity leak from other dimensions?

[tehcyder]

You mean apart from the complete lack of evidence of other dimensions?

Duh, what about the evidence of gravity leak from other dimensions?

Re:Gravity leak from other dimensions?

[Anonymous Coward]

absence of evidence is not evidence of absence

Re:Gravity leak from other dimensions?

[KGIII]

You'd think that would work when you skipped Physics 201 because it was too damned hard...

Re:Gravity leak from other dimensions?

[Anonymous Coward]

As we stand in the middle of a conversation about matter we've conveniently labeled as dark**

Here, I'll illustrate your wrongness with an analogy which should make sense to you.

You're standing in a dark room with one other person. You know he's there because you can feel his dick in your ass. Suddenly, you get hit in the face, which doesn't make sense because you know for certain that the only other person is standing behind you, furiously stretching your anus. You may decide this indicates the presence of another, previously unknown, black man in front of you. Or you might come up with an idea that a being of pure homosexual energy from another dimension opened a portal in front of you, and slapped you in the face with it's fist-shaped cock. Now as much as you personally desire the second idea to be true, it is far more likely and in line with known evidence for the first one to be true... even if in you later discover the person is a Cracker or a Slope instead of a Darkie that hypothesis is still far more correct than the one you're proposing.

Re:Gravity leak from other dimensions?

[rahultyagi]

I know what you mean, but saying "For light, dark matter just isn't there" isn't quite right. It isn't there in terms of electromagnetic interaction. The gravity, on the other hand, can't be escaped even by photons. Otherwise you wouldn't have seen the lensing effects that are some of the best evidence for dark matter's existence.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

I wouldn't call it lack of evidence, but lack of experimentally verified evidence maybe.

https://www.youtube.com/watch?v=jStudmvBkOY

Re:Gravity leak from other dimensions?

[Anonymous Coward]

Are you trolling? Your argument boils down to "bananas aren't yellow because they're quite different from yellow cars". It's stupid.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

Is there clear evidence to discount the Holy Spirit? Of course not. If you think "dark stuff from other dimensions" is a viable hypothesis you have to 1. explain what "other dimensions" even means, 2. propose an experimental test for it. Until then I call woowoo.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

Absence of evidence is also not proof of existence.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

Patience, my friend. In time, he will seek you out, and when he does, you must bring him before me. He has grown strong. Only together can we turn him to the Transparent Side of the Force.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

This is the first time I have ever wanted to see a moderation option for +1 Troll.

Re:Gravity leak from other dimensions?

[HiThere]

If that were so, it wouldn't produce gravitational lensing. And it does, because that's the main argument that it exists.

Re:Gravity leak from other dimensions?

[nedlohs]

Actually yes.

If something doesn't interact electromagnetically it must be transparent. The reverse isn't true of course, but that wasn't claim.

Re:Gravity leak from other dimensions?

[Bengie]

There is a difference between a refractive index and a warping of space time.

Re:Gravity leak from other dimensions?

[Anonymous Coward]

This deserves the coveted +5 Troll

Re:Gravity leak from other dimensions?

[idji]

I like "dark matter" because it doesn't interact electromagnetically, i.e. shine light on it and you won't see it, but it does react to gravity. Glass or water is "transparent matter".

Co-gravitation

[Anonymous Coward]

None of the references point to co-gravition, or Heaviside's force, which seems to produce much of the desired results called for.

Co-gravitation just requires to rethink the nature of energy, though, since it implies that the gravitational field is a sink of energy,

Re:Co-gravitation

[Anonymous Coward]

Co-gravitation just requires to rethink the nature of energy, though, since it implies that the gravitational field is a sink of energy, Flag as Inappropriate.

That's not my name.
-- Reply to This

Re:Co-gravitation

[Xyrus]

None of the references point to co-gravition, or Heaviside's force, which seems to produce much of the desired results called for.

Yes, all those references on over unity are really convincing. Love the youtube anti-grav videos as well. I'd tell you more but the gubmit will probably be breaking down my door to steal my plans for the Death Star. :P

Sorry, I don't believe in conspiracies or magic.

Re:Co-gravitation

[Anonymous Coward]

I don't believe in conspiracies or magic.

Really? So you don't even believe in any of the many conspiracies that have been proven and documented? Wow.. You don't sound like a very rational person.

Re:Co-gravitation

[Coren22]

conspiracy
knspirs
noun
a secret plan by a group to do something unlawful or harmful.
"a conspiracy to destroy the government"
synonyms: plot, scheme, plan, machination, ploy, trick, ruse, subterfuge; informal racket
"a conspiracy to manipulate the results"
the action of plotting or conspiring.
"they were cleared of conspiracy to pervert the course of justice"
synonyms: plotting, collusion, intrigue, connivance, machination, collaboration; treason
"conspiracy to commit murder"

Re:Co-gravitation

[HiThere]

Sorry, but conspiracies are not necessarily illegal. Most aren't. Even the ones that are legal tend to be quite secretive, because the motivation for conspiracy is generally to benefit the members by use of hidden information. But not all conspiracies are even secretive, as some benefit merely be conjoined actions.

Con-spiracy: To breathe together. As in people gathered around a table.

Re:Co-gravitation

[Coren22]

You can argue the definition if you choose, I just posted the definition off of Google.

A conspiracy is when multiple people plot to do something. Yes, it doesn't have to be unlawful, as the definition says unlawful OR harmful, but I can't imagine a conspiracy that was legal, so I am not sure what you mean by that.

Co-gravitation

[os2fan]

None of the references point to co-gravition, or Heaviside's force, which seems to produce much of the desired results called for. Co-gravitation just requires to rethink the nature of energy, though, since it implies that the gravitational field is a sink of energy, Flag as Inappropriate. A good deal of work has been done by the likes of O. Jeffimenko, and more recently T de Mees. Heaviside suggested the necessary forces in 1893.

WTF

[Anonymous Coward]

Haven't u people ever considered that the reason we can't see this matter is that it's matter that has cooled over billions of years and is the remnants of supernovas? Maybe we should be looking for gravitational-lensing effects that would point this matter out. Also, maybe super-massive black holes have a hell of a lot more matter than we are given them credit for, folks?

Personally, I believe super-massive black holes explode, but it takes a hell of a long time for us to ever notice. A good example of this would be the sombrero galaxy or any of the numerous elliptical galaxies in the universe. Do the math on those galaxies (matter wise), and extrapolate that data and apply it to galaxies with black holes, and I'd bet a dollar to a donut that u start finding all kinds of matter that actually does exist.

R.G.J.
 

Re:WTF

[Anonymous Coward]

Maybe we should be looking for gravitational-lensing effects that would point this matter out.

That is how people identify it; look at the Bullet Cluster.

Also, maybe super-massive black holes have a hell of a lot more matter than we are given them credit for, folks?

That wouldn't match the observed distribution. If matter of any form explains the observed differences, it must be diffuse.

Re:WTF

[Anonymous Coward]

You've done that math then have you?

Re:WTF

[Anonymous Coward]

Haven't u people ever considered that the reason we can't see this matter is that it's matter that has cooled over billions of years

LOL. Cold Dark Matter (CDM) is the leading hypothesis https://en.wikipedia.org/wiki/Cold_dark_matter

Re:WTF

[Sique]

If you RTFA, you would see exactly that issue adressed with two colliding galaxies. You can see the (baryonic) dustclouds collide by the emitted light and the dark matter moving straight indicated by the graviational lensing.

Re:*** Slashdot is spying on you. ****

[Anonymous Coward]

If you nutthead would head your browser to janrain.com, taboola.com, etc. you could easily find out what they are for. It's not as if they are operating in secrecy, they have extensive information on their ad/customer tracking businesses on their sites. Just sayin'...

Anyway, why don't you just install NoScript and an uBlock like the rest of us?

Dark matter is no magic

[Anonymous Coward]

Just to place things back in context: dark matter nothing weird or magical. What we see from the outer space tends to be the bright things (like stars), plus what blocks their light (already much less obvious). So when we need more mass for the current models to apply, we have plenty of space for matter that we just don't see, because it's dark on a background that's quite dark too. And you know what, we could call that with the very scary magical name: "dark matter"!

Re:Dark matter is no magic

[Anonymous Coward]

No. We understand that. You are talking about perfectly mundane non-observable matter.

Re:Dark matter is no magic

[HiThere]

"Dark matter" is certainly nothing magical, though I do consider it weird.

The main problem with it is that it's defined only in terms of indirect effects. This is typical of subatomic resonances, i.e. extremely transient subatomic particles. It's not what one expects of something stable. Even the neutrino has been detected. (And I have my doubts about the graviton...either it's unstable, or we don't understand gravity, because we *should* have already detected it.)

So. I think the term "dark matter" is wrong because it oversimplifies things. I expect there is an entire particle zoo of dark matter particles, and that they don't interact electro-magnetically, but they do interact with gravitons in a way that disrupts them. This means that there need to be several non-electromagnetic forces that they interact with...so clearly this explanation violates Occam's razor, but I believe it anyway, partially because it explains why we haven't yet detected gravitons.

So I agree with the earlier poster that "dark matter" is handwavium. Unfortunately, I can't see how we could detect any "dark matter" particles directly...and that's what would be needed to make my hypothesis anything more than hot air.

The problem with calling "dark matter" handwavium is that as no alternative is proposed, people extrapolate unreasonable meanings. (If "dark matter" is ill-defined, there's no word for how ill-defined "handwavium" is.)

A Foundational Mathematical Logician's View

[John Allsup]

The problem physics faces is that it is using mathematical methods which assume physically implausible foundations. It is then faced with the problem of incomplete knowledge. I shall illustrate the issues using metaphors that anybody with half an ounce of computer science common sense should get. (For reference, my area of doctoral studies was models of PA, in the region of mathematics which gave birth to modern computing.)

Consider modern hashing. If I know the correct input, I get the correct output. If I am off by one bit, but do not know which bit, and the input is 128bits, I have a 1/128 chance of getting the correct output. If I am off by two bits, I have a (1 / 128 choose 2) chance, and as the number of bit errors increases, this probability gets close to zero. Quantum mechanical effects occur when the number of bits of entropy get small, so that this probability becomes experimentally distinguishable from zero. Something like that.

Now consider that energy and mass are equivalent via Einstein's famous equation. Neglect the complex stuff for now. The current theoretical best idea is matter being vibrations in strings. For now I will just take a conceptually simple version to illustrate. A short vibration in a long string takes time to travel, and if this speed is c (lightspeed) and the string is long and coiled, it will take time to get to a place where one particular observer can see it. Likewise photons have to reach us before they can register. Of course interactions between matter through the elecromagnetic field happens via photos.

The obvious explanation is that there is some hidden delay in the underlying physics so that only, say, 5% of the energy in the universe is visible to an observer at any time. What this '5%' actually is will follow from the underlying structure, but quite possibly this cannot be probed by conventional experimental means since it is necessary that the part of the universe experimented on needs to be held constant, thus precluding conventional experiments using physical objects. Again, this is a sketch idea to be pondered, not a claimed 'final theory'.

The thing is, if energy is invisible due to delay, but still contributes to the overall mass inside our universe, these 'dark energy' type sum mismatches might be the only evidence they are there at all. But getting this right means getting the mathematical framework right, and mainstream theoretical physicists are still mostly using stuff done with methods that were beginning to become unstuck in the late 19th century. Issues with calculus gave rise to analysis using limits, and these were founded on arithmetic and set theory. But these last two assumed an infinitude of distinct objects with which to perform computations. It is known now that this is physically implausible. Thus one needs to use more strictly bounded arithmetics and recursive constructions using precisely accounted computational resources to form foundational models which can correspond to physically plausible structures. By studying such structures and limiting towards the ultimate capacity of the physical universe (think Bekenstein bound here) we will be better placed to sort out this theoretical mess. Current mathematical methods are simply not up to the task.

(google "John Allsup Mathematical Genealogy" and see where I fit in the Ph.D. tree to get an idea of the area I was trained in: life circumstances rendered a conventional career infeasible, which is why I have no academic reputation, but I have kept an eye on progress, and have kept my logical reasoning skills sharp, just in case.)

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

(google "John Allsup Mathematical Genealogy" and see where I fit in the Ph.D. tree to get an idea of the area I was trained in: life circumstances rendered a conventional career infeasible, which is why I have no academic reputation, but I have kept an eye on progress, and have kept my logical reasoning skills sharp, just in case.)

Hence you're just another armchair physicist.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

(google "John Allsup Mathematical Genealogy" and see where I fit in the Ph.D. tree to get an idea of the area I was trained in:

The art of leaving things on the web marked "check out who I got my PhD from?"

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

Stop being autistic. Go outside.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

"life circumstances rendered a conventional career infeasible"

You mean the fact that you are a loon? That never stopped anyone.

Re:A Foundational Mathematical Logician's View

[BitZtream]

Consider modern hashing. If I know the correct input, I get the correct output. If I am off by one bit, but do not know which bit, and the input is 128bits, I have a 1/128 chance of getting the correct output.

No. You don't.

In any given modern hashing algorithm, any single bit error in any part of the process before the very last round should result in an change of at least half the bits in the output.

Change one input bit on a 128bit output, you'll get 64 output bits changing. If you don't, the hashing method isn't even worth beginning to discuss using it for something other than silly discussions.

Your simple mistake here is exactly science at this level is truly a joke. One simple bit error completely changes the outcome of the hash, and due to the extrapolation levels in astrophysics, the same thing is probably and happens there occasionally as well.

Re:A Foundational Mathematical Logician's View

[justthinkit]

Given the sorry state of physics, there is nothing wrong with hearing from alternatives, "armchair" or otherwise.

However, you mix relativity...with string theory -- and you can't do that.

But the biggest wtf is that the missing stuff is all *delay*? So, are we do for a gigantic shipment of stuff at some future date? This nonsense suggests you don't know how to vet your own ideas.

So, Mr. Ph.D., you fail in the details, not in whether you are an armchair or "pro" commenter.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

Wow, you're so smart. I wish I could be you.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

However, you mix relativity...with string theory -- and you can't do that.

Um... you can't? Why?

Re:A Foundational Mathematical Logician's View

[justthinkit]

Check out the first answer

Re:A Foundational Mathematical Logician's View

[BitZtream]

Wow, I just read all of your bullshit post.

Lets get a couple things straight. My family has 3 PhDs in it. They're all fucking morons. All it takes to get a PhD is a sponsor, a few years of wasted life and money. The INSTANT you start telling people you're a PhD to give yourself credibility, you lose ALL credibility with anyone who has a clue. If you had a clue, you wouldn't need to ensure us that you have one.

Second, You're post is a rambling bunch of bullshit you made up. It is actually less plausible than magical fairies holding the galaxies together, thats how ridiculous your post is.

I can invent math and formulas that make things work all day long by throwing in 'unknown/untestable' data points. THAT IS NOT SCIENCE, ITS FANTASY.

You don't get to make imaginary shit up to fill in the places you're ignorant off. Science doesn't work that way.

Science is based on testable processes. If its not an objective, testable process, its not science, period. Science has no debates, only proofs. Debates are for people who want to pretend they understand science but in reality just want to push whatever agenda they have. In science you have disagreements and discussions about how you're going to test the disagreement, but you don't debate. Debates are for emotional subjective topics. The exact opposite of science.

And you're imaginary time delay mechanism that apparently auto-resolves a bunch of self created inconsistencies that you didn't even bother to think of ... Well, go back to your PhD sponsor and talk to them, just don't spew your bullshit into the world, some people won't know any better and will believe your bullshit.

What you're doing is making up a religion.

Re:A Foundational Mathematical Logician's View

[PvtVoid]

*Slow Clap*

Even by Slashdot standards, that was really insane.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

The answer which points out that relativity and string theory agree just fine?

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

However, you mix relativity...with string theory -- and you can't do that.

String theory is a direct extension of GR... which is part of why it is so quirky and a pain, as post SM physics is trying to extend GR in the same way relativity was an extension of Newtonian mechanics. Except an extension of a more complicated theory introduces a lot more mess.

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

(google "John Allsup Mathematical Genealogy" and see where I fit in the Ph.D. tree to get an idea of the area I was trained in: life circumstances rendered a conventional career infeasible, which is why I have no academic reputation, but I have kept an eye on progress, and have kept my logical reasoning skills sharp, just in case.)

Simply having a PhD is not really relevant. The issues it not that people are trying to filter for smart vs. dumb, or hard working vs. not, but that a very, very important trait in dealing with new physics theories is familiarity with existing body of experimental work. Having a PhD directly in a field of a particular branch of physics can be difficult to do without some familiarity of this, but is still quite possible and no guarantee.

At the end of the day though, throwing out random new ideas is easy, and new "I wonder if..." ideas are a dime a dozen. It is only useful if you try to check it against observations, even a small fraction of them, but with understanding what else is left to be done. Way too many internet crackpots have some grand theory that matches one or two simple observations, but completely disregard things their theory obvious would struggle to deal with. Just throwing out an idea with no context is not going to get one lauded as a genius, but just makes you like anyone else who has no idea what the actual work involves or what has been done so far... i.e. someone with no background or understanding, regardless of your training.

Re:A Foundational Mathematical Logician's View

[justthinkit]

"String theory implies new physics in - and only in - the quantum regime."

Relativity does not work at the quantum/Planck scale.

Since you are clearly quite clueless about all this, and I have better things to do, I officially exit this "discussion".

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

You seem pretty clueless about what string theory is and why it was created in the first place. The whole point is to address the issues of GR on the small scale, so it was created to extend GR. Just like GR gives you Newtonian mechanics in the appropriate regimes, string theory gives you GR and is in agreement with GR on relevant scales (just about everywhere we can actually observe things currently).

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

"String theory implies new physics in - and only in - the quantum regime."

Yes... and in the English language, this means some random person on the internet confirmed that string theory says nothing new about the larger scale. Not new compared to Aristotle, but new compared to Einstein.

Here, have a Wikipedia page... https://en.wikipedia.org/wiki/M-theory

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

If you prefer books, here... http://www.amazon.com/Elements-String-Cosmology-Maurizio-Gasperini/dp/0521187982

Re:A Foundational Mathematical Logician's View

[narcc]

I see that you have no background in science. Your rambling here is just as absurd as the OP's.

Re:A Foundational Mathematical Logician's View

[Coren22]

It is actually less plausible than magical fairies holding the galaxies together, thats how ridiculous your post is.

I prefer my theory, it is unicorn farts causing the distortion!

Re:A Foundational Mathematical Logician's View

[Anonymous Coward]

My family has 3 PhDs in it. They're all fucking morons.

They're usually the ones that are easier to trick into bed.

Re:*** Slashdot is spying on you. ****

[Anonymous Coward]

Don't bother. It's like arguing with that APK host file guy.

Re:*** Slashdot is spying on you. ****

[Anonymous Coward]

I agree with him.

I didn't consent to receive any of that code, but it was pushed into my browser anyhow.

Or it could be, you know, measurement errors

[Anonymous Coward]

There is a *lot* of extensive extrapolation in cosmology, based on very small amounts of raw data. The result is well described by XKCD in https://xkcd.com/605/

The "dark matter", in particular, involves gravitational analysis of extremely distant sets of objects, whose overall mass is being estimated by optical and radio frequency extrapolation of stellar mechanics and the frequencies of things like supernovae, and exrapolation of Hubble's Costant from admittedly limited observation. So there seems to be a great deal more matter in the makeup of the universe, making gravities orbit more compactly and other interesting phenomena.

But it doesn't necessarily take "new forms of matter" to explain this. It takes matter that is not easy to observe, and there are several candidates that do not require rewriting basic physics. Galactic black holes that are larger than expected, but masked by the rest of the galaxy, are good candidates. So are stellar clouds, which seem to be more frequent than expected, too small to be easily remotely observed, And frankly, so are the startling plethora of "rogue planets", planets which orbit no suns, which we're only beginning to observe as space-based telescopes improve.

Frankly, "dark matter" is like "magnetic monopoles". It works in mathematical models, but hasn't shown up in experiments and is not a *necessary* to explain how things work. Simpler models are powerful and elegant enough to cover the existing structure.

Re:Or it could be, you know, measurement errors

[mrsquid0]

> Frankly, "dark matter" is like "magnetic monopoles". It works in mathematical models, but hasn't shown up in experiments and is not a *necessary* to explain how things work. Simpler models are powerful and elegant enough to cover the existing structure.

I am breaking my usual rule of not responding to anonymous cowards, but the quoted statement is wrong at several levels and I am feeling masochistic this morning.

The idea of dark matter does not come from mathematical models, it comes from observations. The standard model of particle physics does not predict dark matter. Dark matter was detected in experiments (or observations if one wants to be pedantic). There is no theoretical basis for dark matter, but there is a large body of evidence, from many different types of observations, supporting the idea that dark matter is a real part of the Universe. At present there are no theoretical alternatives to dark matter than can reproduce what we observe in the sky. Unless the past 80 years of observations are wrong then dark matter is necessary to explain what we see. There are no simpler models. Many have been tried, including small- and large-scale changes to gravity, and none have been able to reproduce what we actually observe.

Dark matter is not simply a measurement error. There are too many independent observations that all point to the existence of dark matter. Not only that, they all point to the same amount of dark matter and require that similar properties for dark matter. Measurement errors do not always work in the same direction across vastly different types of measurements. Bib Bang nucleosynthesis and the COBE/WMAP/Planck observations are completely different from galactic rotation curve and cluster velocity dispersion measurements, and yet they all predict consistent amounts of missing mass. Stray planets and low density clouds of cold gas are not enough to close the gap. Even if they did work for galactic rotation curves they would not be able to explain the results of the cosmic background radiation observations.

Re:Or it could be, you know, measurement errors

[Bengie]

All obvious candidates have been accounted for and failed. It comes down to this. Whatever Dark Matter is, it can't be baryonic. It has to be slow moving, which means massive, it can't interact with itself easily, and it can't interact with the electromagnetic force. Of all known matter, none of them foot the bill without some serious modifications that are more ludicrous than Dark Matter itself.

Re:Or it could be, you know, measurement errors

[beastofburdon]

Measurement errors do not always work in the same direction across vastly different types of measurements

They do when they all use the same flawed method of measurement.

and I am feeling masochistic this morning

You must be. You are clinging to this theory with religious fervor even when a casual observer can see that it is full of shit.

Headlinium

[Anonymous Coward]

Doesn't matter. The power of headlinium can still dazzle even the most skeptical grant committees.

Captcha: mediocre

Re:Headlinium

[Anonymous Coward]

Yes, we know. Slashdot uses evocative captchas. It's SO amusing that nerds don't complain about the breaking of W3C standards by using captchas in the first place.

But you're the *first* person to notice. Bravo.

Why so negative?

[wonkey_monkey]

New Hubble Release Puts Another Nail In the Coffin of Dark Matter's Competitors

Well that's a gloomy spin on it. What about "New Hubble data advances scientific understanding of the universe. Go science!"?

Re:Why so negative?

[Anonymous Coward]

Because today's "Science!" crowd is acidic and vengeful. It's sad but true.

Re:Why so negative?

[Anonymous Coward]

Modern cosmological speculation needs to be shored up with propaganda. It's either that or engage in collegiate debate.

Re:Why so negative?

[ceoyoyo]

Because the defining characteristic of science is that you test your crazy ideas and figure out which ones might be true.

Re:Why so negative?

[wonkey_monkey]

Because the defining characteristic of science is that you test your crazy ideas and figure out which ones might be true.

By rejecting the ones that can't be true.

And that's exactly what's happened. One of dark matter's competitors has been tested and is now in the "can't be true" box.

Re:Why so negative?

[ceoyoyo]

Yup. You might even say that another nail has been pounded into the lid of it's "can't be true" box.

Re:Why so negative?

[wonkey_monkey]

Well that's silly. If we nail the lid shut we won't be able to put anything else in there.

Re:Why so negative?

[ceoyoyo]

Lots of little coffins. One for each crazy idea that didn't survive contact with science.

Re:Why so negative?

[wonkey_monkey]

Lots of little coffins.

Oh, no, that's just sad. And a bit creepy.

Re:Why so negative?

[ceoyoyo]

But very Darwinian.

Re:Why so negative?

[beastofburdon]

Which would be devastating to the current theories of cosmology.

Help ME grAVitation. Because I'm falling.

[Anonymous Coward]

Listen Up HUmans

You need to concentrate on FUsion power. If YOU can master FUsion (real fusion that has a net gain, not FLourescent light bulb FUsion), you can generate enough energy to create a massive singularity which can fold time space and allow you to travel to distant locations in the universe as easily as walking through a doorway.

Concentrate on FUsion right now, not chemical rockets or FLoursecent lights.

You will achieve if you study all of the paraMEters.

Re:*** Slashdot is spying on you. ****

[Anonymous Coward]

Buddy, I realize this is new to you but there are browser add ons that take care of this if it bothers you.

Do a google search for these search terms:

Ghostery
Ad-Block
Incognito

these are pieces of software that you can install called "Plug-ins" that add functionality to your browser.
These three allow your computer to ignore these "Spy" components you have just now noticed on slashdot. (Actually they are all over the web. You would be hard pressed to find a site out there that does not have these types of spying components in it's code.)

Go and do some research on how to protect your privacy by googling and installing some plugins on your browser.

Good Luck!

A bit

[Anonymous Coward]

sensational. More like a reaction to LUX (no) results. http://arxiv.org/abs/1310.8214

on the other hand

[tomhath]

The best proof we have for it so far is that if it isn't there the model we use doesn't work.

If it is there the model works perfectly. We can see the effect it has on gravity, we just we don't know how to detect it directly.

The reason why we keep talking about dark matter

[Sla$hPot]

is the lack of grey matter.

Properties of spacetime

[little1973]

What about if spacetime itself has some properies? Eg. tension? At relatively short distances the curvature of spacetime diminishes with r^2. However, as we go further and further from the center of the curvature, spacetime reaches flatness slower and slower. This can explain the galaxy rotation problem and other phenomena which requires dark matter.

This is similar to what MOND tries to achive, but unfotunately MOND does not say anything about spacetime.

Re:Properties of spacetime

[ceoyoyo]

Read the article. They tested a relativistic version of MOND that DOES say things about spacetime. It failed. Modifications of gravity also fail to explain things like the bullet cluster.

Re:Properties of spacetime

[little1973]

Even wikipedia states that the bullet cluster is not exactly a proof for dark matter.

https://en.wikipedia.org/wiki/...

The proof for dark matter is solely base on gravitational lensing and that is disputed.

Re:Properties of spacetime

[ceoyoyo]

There's no such thing as "proof." The Bullet Cluster is evidence in favour of dark matter, and, as I said, it's pretty strong evidence against MOND.

Dark matter, heavy neutrinos and anti-matter

[SloWave]

I've seen some speculation that dark matter could be a previously unseen heavy neutrino. I also understand based on current theories there should be a lot more anti-matter than is seen now in the universe. So my armchair physics idea is there was some reaction as part of the matter/anti-matter annihilation in the early universe that converted a lot of the anti-matter into the dark matter forms of heavy neutrinos. Has this idea been pretty much ruled out already?

Re:Dark matter, heavy neutrinos and anti-matter

[Anonymous Coward]

Yes, there are theories like sterile neutrinos and they were popular for a while, but their predictions are running into problems with recent particle experiments on Earth.

Re:Dark matter, heavy neutrinos and anti-matter

[Buchenskjoll]

I've seen the heavy neutrino. It doesn't cut or wash its hair, it drinks beer out of the can and it says "Dude" all the time.

Re:Dark matter, heavy neutrinos and anti-matter

[slashdice]

I am Heavy Neutrino Guy....and this is my neutrino. She weighs 0.320 ± 0.081 eV/c2 and weakly interacts with gravity. It costs four hundred thousand dollars to detect this particle...for point twelve seconds.

Ahahahahahaha!

Oh my god, who touched Sasha? Alright. Who touched my lepton!?

Some people think they can outsmart me. Maybe, maybe. I've yet to meet one that can outsmart muon.

Waaaahhhhh! Uraaaaaaah! Ahahahahahaha! Cry some more!

Heheh, cry some more.

7.2 mm a year...

[rgbatduke]

He had me right up to that point. But an assertion that one can measure the position of two kilometer scale objects many, many light years away to a precision OR accuracy of 1 cm (they claim a few THOUSANDTHS of a millimeter) is, frankly, incredible.

One guesses that they do no such thing -- instead they measure the temporal period of the orbit and infer the mutual radius on the basis of its slow shift. Our ability to slice time precisely is far greater than any angular resolution of an optical instrument, so I'm willing to believe that they observe a slow shift in orbital period. But then they aren't measuring orbital radius change to a precision of thousandths of millimeters, they are measuring orbital period, and further, they are assuming that gravitational radiation, which has yet to be directly observed and hence is still at best an attractive (pun intended) hypothesis, is the cause of the shift. But one could imagine other causes. The problem is that their inference begins to be built up out of an increasingly long tower of assumptions -- that (for example) the substantial tidal deformations of the stars as they orbit, the possibility of spin-orbit coupling, or interaction with further bodies unseen are responsible for the period shift and not just gravitational radiation. It always worries me when an experimentalist claims "99% agreement" with a theory in a measurement performed on something that far away -- my own experiences in more mundane research projects in earthly labs is that one almost never gets 99% agreement with a theory simple because it is difficult to measure all that must be measured precisely and accurately enough to get a number that precise.

There are exceptions, of course -- usually exceptions that arise after spending decades making a series of highly precise measurements in a carefully constrained environment, such as measurements of G or the electromagnetic couplings -- but I'd prefer a claim of consistency rather than proof of a theory in things like this, and would prefer it even more if the actual experimental result was announced, not the inference based on further assumptions that become additional Bayesian priors to the conclusion and that are not stated.

This isn't to defend alternatives to dark matter -- I have no dog in either fight -- only to point out that arguments for dark matter always end up being arguments against it being anything else. Of course this is the way it has to be -- dark matter is dark, an invisible fairy, which means that you can make it do anything without fear of refutation because, well, it is invisible. But it is spectacularly difficult to argue for a theory on the basis of null results for alternatives, simply because we may not have thought up the right alternatives yet. What is needed, of course, are direct observations of dark matter to put the matter to rest.

Darned invisible fairies, anyway! Maybe it hangs out in the same fairy bar with magnetic monopoles and Higgs bosons, although it is possible that Mr. Higgs has finally come out into the light of day.

rgb

Re:7.2 mm a year...

[beastofburdon]

Wow, that is the most sane post I have seen so far in this thread.

scientific religion

[Anonymous Coward]

So I am a nutter for believing in a God that I can't see or prove exists but a scientist believing in dark matter which can't be seen or proven exists is logical?

Re:scientific religion

[Anonymous Coward]

You're not a nutter. You're an idiot. You and every other fucking moron posting in this thread who is ignorant of the body of evidence for dark matter can go fuck off and die. Dark matter has been mapped, dipshit. We know where it is.

You and everyone else are just retarded buttheads who are willfully ignorant of the evidence.

YOU COWS!

Re:scientific religion

[Anonymous Coward]

Very insightful.

In fact, dark matter might be the luminiferous aether. That it wasn't observed when testing earlier can be explained by its having been at a tea party with phlogiston and the bodily humors at the time.

Re:scientific religion

[Anonymous Coward]

Yeah gravitational lensing totally doesn't exist!

You're so smart, dude! I'm with you, bro. Those stupid scientists don't know anything, and their lies are what's keeping us from having warp drive and transporters!

Not unhappy to see MOND stumble

[Anonymous Coward]

Dark matter is an acknowledgment of ignorance; MOND is a hack attempting to conceal that ignorance. MOND deserves to die.

Silly, shortsighted midgardians!!!!

[Dubbel]

If you had even an infants' understanding of Norse cosmology, you would include the mass of Asgard, Vanaheim, Alfheim, Jotunheim, Svartalfheim, Nidavellir, & Muspelheim in your calculations. Thor is not pleased. https://upload.wikimedia.org/w...

Re:*** Slashdot is spying on you. ****

[KGIII]

Unfortunately, you consented by opening the URL. Block that like the rest of us do. I'm reasonably certain that their metrics are completely screwed.

Re:The reason why we keep talking about dark matte

[KGIII]

Well, I'm no astrophysicist but I do watch a lot (too many, according to my girlfriend) documentaries on this very subject. If you have a competing model and the mathematics to suggest it might be true then, by all means, share! (I am a mathematician but, frankly, that doesn't make me qualified to opine on matters of physics but I am very interested - especially in alternative theories. Remember, they thought Einstein was wrong until they managed to take pictures of a solar eclipse.)

My kingdom for mod points!

[gerald.edward.butler]

Your have my vote for BEST ANALOGY EVER!

Re:My kingdom for mod points!

[Anonymous Coward]

You never thought your deepest desire would ever see print, did you?

Electricity

[Orgasmatron]

Can anyone post on the current understanding of electrical forces on galactic scales?

A while back I read a bunch of papers on preprint archives suggesting that the effects that we see as dark matter could be caused by the electric force. I don't have my bookmarks handy, but I recall some credentialed and not-obviously-crazy physicists saying that the idea had enough merit to warrant investigation.

Has that gone anywhere?

Re:Electricity

[tohoward]

This has always been a good question in my mind. We have a generally agreed upon understanding of four fundamental forces (granted, depending on how they are grouped, the number is +/- 1), but only two that are understood to operate on large scales: gravitational and electromagnetic.

It has always seemed to me that there is an inherent desire to explain "dark matter" as a gravitational phenomenon ("matter"), and that an attempt to quantify the forces involved and determine if there exists a possible electromagnetic charge & current distribution that fits the force profile would be a good place to start looking for an explanation...but I never see any attempt to do so (granted, I don't work in the field). My assumption is that either this has been tried an discarded, or that there are other observations that would exclude this as a possibility. The closest thing I discovered was this: http://www.futurity.org/can-regular-electromagnetism-explain-dark-matter/ which isn't really an electromagnetic approach, but rather a "mass based" approach that has unique electromagnetic properties.

In any case...I second the motion. Is anyone aware of any attempt to categorize "dark matter" in this way?

Re:Electricity

[Anonymous Coward]

There are maps of the milky way's magnetic field which is pretty weak, and ways of measuring electric and magnetic fields at a distance via spectroscopy (line splitting). I don't know the numbers off the top of my head, but there are measurements and research out there for someone curious enough to look into it.

Re:Electricity

[tohoward]

I got curious and did some deeper googling and found this: http://arxiv.org/pdf/1406.0283v1.pdf

It's a survey of current attempts/papers that describe the galactic EM field.

Re:Electricity

[Bengie]

Dark matter has also been discovered in galactic voids. This would never be explainable by the electric force, which requires normal matter to be present.

Re:Electricity

[Anonymous Coward]

An electromagnetic approach would have trouble explaining the lensing seen that happens to also match the amount of dark matter mass needed for observed behaviour in galaxy clusters. The thing that separates gravitational lensing from most other electromagnetic phenomena, is how it is wavelength independent unlike pretty much all known sources of index of refraction that could also cause lensing.

Re:Electricity

[beastofburdon]

Here is your answer: http://www.electricuniverse.in...
The theory was discounted without any testing or any real discussion at all by the primary academic groups, but there is a fringe of physicists who have been actively working on this for several decades. They are considered lunatics by the establishment, but many of their predictions are proving to be true with newer evidence that leaves the establishment scrambling for a new "dark matter" to slap onto their theories.

Re:Electricity

[beastofburdon]

If you think that we can measure the magnetic field of the galaxy accurately, or even vaguely close to accurately, then you are a fool. We have very little understanding of the magnetic fields in our own solar system, much less the entire galaxy.

Re:Electricity

[beastofburdon]

No it wouldn't. Light can be bent in powerful magnetic fields. This has been known for decades and immediately ignored in every discussion on astronomy.

Typical liberal thinking

[Anonymous Coward]

When people point out there must be a Creator for anything to exist at all, they shout them down with "Occam's Razor".

When people point out that Occam's Razor suggests our models are imprecise, they shout them down with imaginary made-up invisible "dark matter" unicorns hiding in outer space.

Re:Typical liberal thinking

[Anonymous Coward]

Yeah, those damned liberals just make shit up like gravitational lensing because they hate us and don't want us to have warp drive!

Then they want me to believe in these "electron" unicorns that are too small to see! Damned liberals.

Modified inertia by a Hubble-scale Casimir effect

[kitsi]

The MiHsC or Quantised Inertia is much better alternative to the "complex fudge" of dark matter dark than MOND:

MiHsC has no adjustable parameters, and predicts cosmic acceleration and galaxy rotation without dark matter.

Be warned, the author's blog "Physics from the edge" has some quite good reads:

• • An Introduction to MiHsC
  • Debate on the facts.
  • MiHsC vs 29 anomalies
  • Resisting the end of physics
  • ...

Modern day epicycles

[Anonymous Coward]

When the heliocentric model of the universe was proposed, one of the complaints was that it was far less accurate than the existing geocentric model. Why? Because people had spent ages adjusting for inaccuracies by adding epicycles. That's all dark matter is: epicycles for the modern age.

Re:Modern day epicycles

[Anonymous Coward]

No, by the time heliocentric models will being proposed, the epicycle models were already found to be inaccurate. There was already some question of whether it was possible to computer it with more layers, or if observations were wrong, but mostly just disorganization enough that people didn't notice how systematically wrong they were.

Re:Modern day epicycles

[Anonymous Coward]

The one thing I will never understand about the /. crowd: the absolute hatred for dark matter. Are you mad because those evil liberal scientists have shattered your dream of galloping around the cosmos in the Enterprise?

Yep, looks like epicycles to me.

[Top] - Three slices through the evolving distribution of dark matter. The dataset is created by splitting the background source galaxy population into discrete epochs of time (like cutting through geologic strata), looking back into the past. This is calibrated by measuring the cosmological redshift of the lensing galaxies used to map the dark matter distribution, and binning them into different time/distance "slices". Each panel represents an area of sky nine times the angular diameter of the full Moon. Note that this fixed angle means that the survey volume is a really a cone, and that the physical area of the slices increases (from 19 Mpc on a side to 31 Mpc on a side) from left to right.

[Bottom] - When the slices across the universe and back into time are combined, they make a three-dimensional map of dark matter in the universe. The three axes of the box correspond to sky position (in right ascension and declination), and distance from the Earth increasing from left to right (as measured by cosmological redshift). Note how the clumping of the dark matter becomes more pronounced, moving right to left across the volume map, from the early universe to the more recent universe.

Please enlighten us with your elegant theory that will explain the current observations. Bonus points if it allows for warp drive.

Re:Handwavium (like gravity)

[Anonymous Coward]

I've never seen gravity, either, but I still see that things fall.

And I believe that stars wouldn't work right w/o gravity (gravity balances the
pressure created by fusion/temperature), so I imagine that gravity exists off
the Earth as well.

There's just some difference in the speed of the handwaving (i.e., the size of
the unknowns involved). We've never seen dark matter (and won't, kinda by
definition), just like we've never seen a graviton.

Branes

[dhaen]

If we had the branes, w'e know the answer.

Could tired light be an alernate explanation?

[Anonymous Coward]

As I understand it (basic physics plus lots of Azimov), the dark matter theory (and others) are predicated on the red-shift indicative of an expanding universe (light source moving away more quickly with distance). So what if photons lose energy at an infinitesimally small rate as they propagate for eons? That would mean a non-expanding universe is possible and no need for dark matter (nor the big bang for that matter). This isn't an original thought by any means but is there any direct evidence that light can't possibly "get tired"?