back to article Dark matter drought hits older galaxies: Boffins are, rightly, baffled

The mystery surrounding dark matter deepens: scientists have discovered that the puzzling substance was less dominant in our universe's early galaxies. Although no one knows what dark matter is made out of, physicists generally agree that it exists, and that it can be observed albeit indirectly. In the 1970s, astronomers …

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Does dark matter?

Maybe they are finally on the track of proton decay?

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Re: Does dark matter?

Protons don't decay.

At least not over any reasonable count of universe lifetimes.

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Headmaster

Scientists get their maths wrong and so rather admit it, they make up dark matter. If only I'd known I could do that back in my school days !!!

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Joke

"If only I'd known I could do that back in my school days !!!". I am sure you did.

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Most of physics and cosmology involve performing observations and then trying to develop a mathematical model (tied to known laws of physics) that matches those observations. Then the model is examined for clues that could predict future observations. If such predictions are proved, it gives a big boost to the model and the theory behind it.

The early galactic models were predicated on the assumption that what we saw was what we got. Then what we saw failed to match the model and so it was discarded for another that includes extra mass we can't see.

The new model matches the observations, but it doesn't indicate the nature of the mass. No one got any maths "wrong" and in fact the cosmologists were quite pleased that the old model was wrong, because that makes their job much more interesting.

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@ Big John, To me dark matter and dark energy point to a fundamental problem with our theories much like the situation in theoretical physics at about 1900. My nagging suspicion is more based on the fact that neither can be observed.

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Something is making the galaxies spin wrong. Either it's a whole lot of extra mass/energy at the edges of galactic disks, or it's because we are missing something major about gravity itself. It can't be denied that no well accepted theory of Quantum Gravity currently exists, and there has to be one or the rest of physics is going to hear about it, very loudly. So there's room yet for weird changes to our perception of reality.

Say, perhaps dark matter is really just a build up of 'tired gravitons' around the galactic disks? That would explain the increasing effect over time... :-D

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Or it could be that dark matter is created through some process we don't yet understand. Maybe supernovas create it, or stars themselves radiate it along with photons and neutrinos.

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@a_yank_lurker, Maybe they could even go back and re look at the old aether theory which appears to fit the facts they are observing.

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Scientists get their maths wrong and so rather admit it, they make up dark matter.

Meanwhile back in the real world, scientists get their models wrong (because they're mortals working with limited information), admit it, and amend their models.

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@a_yank_lurker

You may well turn out to be correct, but the fact that neither dark matter nor dark energy can be (currently) observed does not necessarily point to that conclusion. Many, many phenomena in physics were predicted long before they could be detected (gravitational waves, as predicted by general relativity, being a recent example).

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re: Many, many phenomena in physics were predicted long before they could be detected

Indeed, that is how science works. Nevertheless, before the proof is concrete it's sensible to take the theory with a pinch of salt.

It does look like a bodge though. Calling it "amending the model to fit the data" sounds better as long as you don't think about it for too long.

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Re: re: Many, many phenomena in physics were predicted long before they could be detected

"Indeed, that is how science works. Nevertheless, before the proof is concrete it's sensible to take the theory with a pinch of salt."

Not quite. As I understand it, the only place concrete proof exists is in pure mathematics (i.e. proving a mathematical statement.) Scientific theories i.e. Einstein's theory of gravity, are impossible to absolutely prove, they just become more accepted as valid as more evidence is found to support them. A theory can be fully or partially disproved in an instant, however, if a prediction that is made as part of said theory is shown to be incorrect. All the science we 'know', is 'just a theory', but some of it has been around so long without being disproved that it is accepted as fact.

You're absolutely right that theories without evidence are taken with a pinch of salt. Peter Higgs (and his team) proposed the Higgs mechanism back in 1964, but didn't receive acceptance of his theory (and the Nobel prize that went with it) until 2013, after the Higgs boson had finally been detected in a two Large Hadron Collider experiments.

And other commentards seem to missing the point when talking about 'scientists getting their maths wrong so making things up.' Science and its theories evolve as our knowledge expands. Newtonian theory works absolutely fine here down on Earth when you're looking at falling apples, moving carriages and spheres dropped from towers. At the scale of the solar system, however, it starts to break down, its predictions in some cases not matching what we observe i.e. Mercury's orbit. Then along comes Einstein, and his description of gravity in the theory of general relativity offers a major refinement of Newtonian mechanics, and matches the motion we see in the solar system exactly.

Then as our view moves ever outwards to study the motion of distant spiral galaxies, we see that again, the currently accepted theory doesn't quite seem to fit what we observe. Either Einstein's theory of gravity is not quite correct, or there is more mass present than we can observe using our current technological capabilities, or possibly both. Given time, I imagine and hope a unified theory of gravity will emerge, and we'll understand gravity to be either a subsequence of the bending of space-time around mass, or the result of the interactions of the gravitons predicted by some quantum mechanics theories, and then we'll have a better understanding of whether the existence of dark matter is needed to explain galactic rotation.

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Re: re: Many, many phenomena in physics were predicted long before they could be detected

It does look like a bodge though. Calling it "amending the model to fit the data" sounds better as long as you don't think about it for too long.

Better than amending the data to fit the model, isn't it? The cyclic process of observation/experiment -> derive theories that explain the observation/experiment -> design observations/experiments that can falsify the theory -> back to step one, means that as we develop and refine theories, they evolve into forms that explain more and more. For example, Newtonian gravity explained far more than Plato's or Aristotle's idea of gravity, which was essentially separate from their model of planetary motion. Newton unified it, and explained the elliptical, rather than circular orbits put forward by Kepler. What it couldn't explain was the precession of the perihelion of Mercury. Einstein's general relativity put forward a single framework that explained both Mercury's odd, and the other more regular orbits, plus a whole lot more.

Replacing general relativity may well be called for to rid ourselves of dark matter/energy, but at the same time the replacement must explain all previous stuff as well.

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galaxies spin wrong

Not "wrong". Just different than expected, based on observations so far.

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Holy Dust!

His Dark Material?

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Gravity can't be observed, either. We deduce its characteristics by its effects.

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Fractal, innit?

"Normal" matter seems to be distributed fractally all the way through from planets, solar systems, star clusters, galaxies, galaxy clusters, etc.

Why wouldn't the same be true of dark matter? Why would dark matter have to coincide with every galaxy equally?

Seems that we are just observing what's out there.

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Re: Fractal, innit?

>"Normal" matter seems to be distributed fractally all the way through from planets, solar systems, star clusters, galaxies, galaxy clusters, etc.

Not just those. Spiral galaxies, sea-shells, bodies, faces, sunflower seeds, bird flight patterns, fingers and hurricanes all made with mathematical precision around a single ratio.

http://io9.gizmodo.com/5985588/15-uncanny-examples-of-the-golden-ratio-in-nature

Of course the universe doesn't have consistent design principles. It just looks like it does.

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Am I right in thinking...

That the light from those old galaxies shows their dark matter situation billions of years ago, and the shape of those galaxies and their dark matter situation today would be very different? Perhaps gravity has an effect on space-time that intensifies as the years go by?

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Re: Am I right in thinking...

Or maybe it took time for the galaxies to 'collect' dark matter. It does seem to be something exotic, so exotic behavior might be expected.

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Re: Am I right in thinking...

@Big John

Collect, or perhaps manufacture. If Dark Matter is a by product a stellar process then as the universe and the galaxies within ages; we will see more of it?

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Re: Am I right in thinking...

and the shape of those galaxies and their dark matter situation today would be very different

Almost certainly. We only have to wait a few billion years to find out. In the meantime, though, we can look at closer galaxies and get a better idea.

Perhaps gravity has an effect on space-time that intensifies as the years go by?

Let's call this the 'inverse knackered elastic band' effect. But since gravity is actually what we call the effect of mass on space-time, you probably don't need to piss around inverting elastic bands...

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Re: Am I right in thinking...

Instead of inventing new (dark) matter to make models and observations line up, I think they need to re-evaluate their assumptions. Their number one assumption is that the gravitational constant is invariant over time and space. Perhaps it isn't (which essentially becomes your idea).

We have absolutely no reason to believe that constants in physics are truly constants in all of time and over all of space. Perhaps the problems with dark matter is evidence that they are not.

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Re: Am I right in thinking...

@Long John Brass

| Collect, or perhaps manufacture.

Possibly even "distribute". It may take some time over the life of the galaxy to displace dark matter from the galactic core and concentrate it at the edges in enough density to cause the observed effects.

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It's from before the photino birds evolved

Obvious, right?

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Anonymous Coward

Dark or light, up or down, positive or negative, alternating current.

Maybe life, the universe and everything works in a different way to what we think.

Circles, spirals, no end or beginning, apply it to science and you could have some interesting theories that could be proved or disproved.

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You've had a really good night in the pub, haven't you?

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Anonymous Coward

Universe

as designed by Thomas Crown

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@Rich 11

Spot on. Maybe left field thinking may surprise us with new science. I don't know, I just like to try and think differently sometimes.

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So,Tesla was right after all?

"Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality."

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Re: So,Tesla was right after all?

Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.

Which is pretty much what Albert Einstein (a contemporary of Tesla) did in his development of general relativity. Except that his "structure" turned out to have a pretty damn strong relation to reality.

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Natascha Förster Schreiber

I'm just impressed by her name!

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Boffin

Neutron dust

Here is my suggestion: Dark matter is neutron dust.

Think about it as ground-up neutron stars. Maybe it's formed in galaxy collisions, or maybe it's a leftover from the Big Bang. Why this neutron dust doesn't aggregate into neutron clumps, you ask? Dark energy of course! The mystery force obviously repels those neutron particles and all the other matter in the observed universe.

Next question please ....

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EBG

Next Question ?

HTF are you going to "grind up" a neutron star, given that it's the most tighty gravitiationally bound class of object in the universe after a black hole ?

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HTF are you going to "grind up" a neutron star

Smash two of them together? Fly it past the edges of a black hole? Us the Big Peppercorn Grinder the Flying Spaghetti Monster uses to spice up its noodly appendages?

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Ether of the 20/21st century physics

I always believed that dark matter is for current physics what Ether was for XIX century one. I.e way to explain observable results differing from current theory, using framework of the current theory. We need new theory, in my very very humble opinion.

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Dark is Imaginary. Big Bang incorrect. WhiteHoleTheory.com

Dark Matter and Dark Energy are non-existent and imagined only to pretend that the Big Bang Theory is correct. When Observations and scientific law conflict with theory, good science questions theory rather than changing the observed facts. Keppler Laws and our observations are correct: rotating galaxies are expanding (No Dark Matter). Galaxies with very high linear velocities do not need "Dark Energy"; they accelerated when they were small and grew larger after achieving high velocity. Galaxies formed from matter which was created gradually by their central white holes. For correct understanding of galaxy formation: see WhiteHoleTheory.com

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Re: Dark is Imaginary. Big Bang incorrect. WhiteHoleTheory.com

1995 called, it wants its website back.

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Re: Dark is Imaginary. Big Bang incorrect. WhiteHoleTheory.com

"When Observations and scientific law conflict with theory, good science questions theory rather than changing the observed facts."

As far as I can tell, that's exactly what this story is about.

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Windows

Head over to nautil.us mag for a pretty good layman-level overview of dark matter explain-away-ery and explanations of MOND.

http://cosmos.nautil.us/

I like it when observation drives physics. Compare with the sterile multiverse crap, where grants drives physics.

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"http://cosmos.nautil.us/"

Wonderful site! Displays SFA except header & footer without allowing javascript. Am I going to enable javascript for it? No.

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"where grants drives physics"

You do know we only want the grants so we can do more physics, don't you.

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@Destroy All Monsters

Fascinating article, but I came away with the impression that MOND theories are at least (if not more) speculative than Dark Matter/Energy theories. Nor, judging by that article, does MOND come across as more data-driven than DM/DE. There is, of course, bound to be resistance to MOND on the grounds that it breaks General Relativity (but then again perhaps General Relativity needs to be broken).

Guess we'll have to wait and see if either approach has legs.

Also, is there really that much grant-related mileage in multiverse theories? They seem to represent, perhaps, more a philosophic than scientific standpoint. From the point of view of science they may well be, as you say, "sterile crap", in the sense that they are not "useful" - they don't seem to make verifiable predictions beyond standard quantum theory. From a philosophical viewpoint, though, they do seem to furnish infuriatingly consistent interpretations for the crazee world of quantum phenomena - where even more traditional interpretations stretch intuition beyond breaking-point.

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I commend your stuckism but ... welcome to 2017 Internet.

Still not running in VMs?

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But what if?

The other possibility that would explain the observations, of course, is that the laws of physics are not constant throughout spacetime - but nobody really wants this to be the case.

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Re: But what if?

Its bad enough for atheists that there is so much fine tuning and the universe started from a causal agent outside of space time, never mind that we can't create a 'simple cell'.

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Re: But what if?

It was nothing of this earth, but a piece of the great outside; and as such dowered with outside properties and obedient to outside laws.

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Re: But what if?

It's not fine tuning, as in "tuned by someone/something". It's just the anthropic principle.

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