[Winstonm]

Wikipedia:

Quote

A small proportion of dark matter may be baryonic dark matter, astronomical bodies (such as massive compact halo objects) that are composed of ordinary matter, but which emit little or no electromagnetic radiation. However, the vast majority of the dark matter in the universe is believed to be nonbaryonic, and thus not formed out of atoms. It is also believed not to interact with ordinary matter via electromagnetic forces. The nonbaryonic dark matter includes neutrinos, and possibly hypothetical entities such as axions, or supersymmetric particles. Unlike baryonic dark matter, nonbaryonic dark matter does not contribute to the formation of the elements in the early universe ("big bang nucleosynthesis") and so its presence is revealed only via its gravitational attraction. In addition, if the particles of which it is composed are supersymmetric, they can undergo annihilation interactions with themselves resulting in observable by-products such as photons and neutrinos ("indirect detection)

It appears we have come full circle - explaining an unexplained phenomenon by creating a supernatural actor to fill the void in knowledge.

Is it dark matter or should we simply call it Zeus?

[helene_t]

Huh? There is nothing "supernatural" about gravity. WTP?

[shyams]

Winstonm, on Aug 27 2010, 02:41 AM, said:

It appears we have come full circle - explaining an unexplained phenomenon by creating a supernatural actor to fill the void in knowledge.

Is it dark matter or should we simply call it Zeus?

I get a sense the latest craze in "dark matter/dark energy" begins to resemble the "ether" phase of physics

[Winstonm]

helene_t, on Aug 27 2010, 02:36 AM, said:

Huh? There is nothing "supernatural" about gravity. WTP?

Nothing is wrong with gravity - but when there is excess gravity and you postulate invisible OD matter as the cause, you may just as well call dark matter the hand of god.

Perhaps the more prudent action would be to reassess the basic propositions than indulge in creation of invisible OD matter?

[OleBerg]

I'm down with gravity!

[vuroth]

Other than the fact that we've known about neutrinos for a danged long time, why does a discussion on a bridge forum seek to second guess the experts in the field?

There's an enormous gulf between "there's matter out there somewhere we can't see" and "hand of god". Science has always had gaps in its knowledge. Rather than just throw up their hands and say "dunno, must be god", science has a long history of theorizing, modelling, and trying to come to grips with the gaps. It's how we learn.

V

[helene_t]

OleBerg, on Aug 27 2010, 02:35 PM, said:

I'm down with gravity!

I am cool with cosmic background radiation!

Anyway, vuroth said it.

[kfay]

vuroth, on Aug 27 2010, 08:44 AM, said:

Rather than just throw up their hands and say "dunno, must be god"

LOL

[USViking]

Include me with those who see nothing godlike about Dark Matter.
It is just another of those many big mysteries that the big guns of
science are paid to spend their working lives trying to help figure out.
Plopping "God" into the issue is an inaccurate and unconstructive
rhetorical flourish.

In this case the problem with looking for a solution by examining basic
propostions is that the propositions needing to be examined are the
gravitational theories of Newton and Einstein. In fact, they would have
to be discarded, because the whole Dark Matter issue arose from the
observation that the rotation speed of galactic objects do not conform
to the predictions of gravitational theory: objects furthest distant from
the center rotate about the center much faster than they should.

A "halo" of dark matter surrounding all galaxies is a logical, parsimonious explanation,
and smearing science which you for some reason do not cotton to
by calling it "God" is luddite.

Of course no theory is holy writ, and all are fair game. Newton himself
was corrected by Einstein's more accurate theory, although Newton
remains good enough to allow us to put a spacecraft through a bullseye
1km in radius in the vicinity of the planet Neptune. Nevertheless, I predict
that Newton and Einstein will remain intact and that those who enjoy
imagining the collapse of great repuations will be disappointed again,
as usual.

[Winstonm]

Quote

...because the whole Dark Matter issue arose from the
observation that the rotation speed of galactic objects do not conform
to the predictions of gravitational theory: objects furthest distant from
the center rotate about the center much faster than they should.

So, does that mean that the original theory is so strong that we must assume magical invisible dust that has to be there in order to keep the original theory on target? I don't know. I would think that when a theory has falsification problems, the idea would be to question the underlying theory rather than to continually create fixes that justify the existing theory.

Didn't we follow this same path of necessary modifications to make the theory work for about 2000 years with the geocentric earth model? I only wonder if we have so much invested in current ideas that we are following the same path?

[OleBerg]

Winstonm, on Aug 27 2010, 08:31 PM, said:

...the idea would be to question the underlying theory rather than to continually create fixes that justify the existing theory.

I'm not a science-man, but my guess is, that this is being done all the time.

[mikegill]

Your analogy to the geocentric theory is faulty. The geocentric model hung on for so long because everyone thought "of course we're at the center of the solar system." They didn't have any proof, they just believed it because it fit with religious beliefs. In this case, our theory of how gravity works only fits every other observation we've ever made in our local part of the universe. Now that being said...

there is a small community of serious scientists who believe that dark matter is not the answer to this riddle. There is a theory called MOND (MOdified Newtonian Dynamics) which (I think) suggests that on large enough scales such as the laws of gravity change. These scientists are very much looked down upon because their opinion is different from nearly everyone else (which I think is not the way science should work).

Cosmology is not my area of astronomy, so I'm trying to not say anything that is clearly considered to be wrong, but I haven't ever heard anything that I thought was 100% clearly definitive proof that dark matter is correct. I don't think any serious scientists would believe in MOND if there were. However, I think dark matter it is a more elegant theory - if the laws of gravity were to suddenly change at some distance scale, why would that be? Why not some other scale? It seems arbitrary and doesn't really make sense. On the other side, we DO know of at least one object in the universe that 1) doesn't emit radiation 2) has mass and 3) doesn't interact with baryons except through gravity - the black hole. A black hole in space without enough matter around to form an accretion disk cannot be detected at all except by its gravitational influence on other matter. It seems to me easier to believe that there exist other such particles/objects in the universe than it does to believe that for some unexplainable reason a law which is known to be correct and constant for all distance scales up to X suddenly changes. That being said, science isn't about what the majority of people believe - it's about who happens to be right, so who knows.

[USViking]

Winstonm said:

So, does that mean that the original theory is so strong...

Stop right there.

The original theory is tied for the lead in the history of science
for confirmation by observation, experiment, and utility.

Utility you say? Yes, besides that camera we flew to Neptune,
closer to home is all that GPS stuff for which the original theory
works pretty darn good, or to put it another way,
it is pretty f*cking strong.

Winstonm said:

...that we must assume magical invisible dust that has to be there in order to keep the original theory on target?

No.

We are permitted to make other assumptions.

For example, serious Dark Matter theorists assume that although
the subject of investigation is neither “magical” nor “dust” it IS invisible.
Anyone gotta problem with “invisible”?

Winstonm said:

I don't know.

You said it, I didn't.

Winstonm said:

I would think that when a theory has falsification problems, the idea would be to question the underlying theory rather than to continually create fixes that justify the existing theory.

The underlying theory has had questions and questioners from the start.
This is not its first challenge.

An analogous recent challenge was the 40-year long
“missing” neutrino problem:

See link:

http://nobelprize.or...ticles/bahcall/

It turned out nothing was “missing” after all, and in 2001-2003
original theory triumphed again.

Winstonm said:

Didn't we follow this same path of necessary modifications to make the theory work for about 2000 years with the geocentric earth model?

No.

For 2000 years we had nowhere near the powers of observation
we now do. Our powers of observation are multiple trillions better
than they were in the day of the great astronomer Ptolemy. If Ptolemy
had had the powers of observation we do now, I think it is reasonable
to assume he would arrive at the same conclusions that we do now.

Winstonm said:

I only wonder if we have so much invested in current ideas that we are following the same path?

I think there is no danger, literally no danger of that.

[luke warm]

USViking, on Aug 27 2010, 12:39 PM, said:

Plopping "God" into the issue is an inaccurate and unconstructive rhetorical flourish.

are you sure it's inaccurate? and, on the off chance that it isn't (inaccurate, that is), would it then become constructive?

USViking, on Aug 27 2010, 04:44 PM, said:

Winstonm said:

...that we must assume magical invisible dust that has to be there in order to keep the original theory on target?

No.

For example, serious Dark Matter theorists assume that although the subject of investigation is neither “magical” nor “dust” it IS invisible. Anyone gotta problem with “invisible”?

not me... very hard to falsify an invisible entity

[Winstonm]

USViking,

It is obvious you have a great store of knowledge in this area. Obviously, I do not - so my questions are genuine and not meant as a criticism of science.

I wonder if the powers of observation you describe are the result of observation or mathematics or some combination? I honestly don't know. My question is whether or not mathematics can explain rather than describe.

To me, this should be important as the validity of the axiomatic assumptions of the mathematical logic determines the validity of any mathematical proof - it is certainly not the same type proof as observational.

Quote

Anyone gotta problem with “invisible”?

Who would? Atoms are not visible, yet we know they exist. The only problem I have is with the concept of an OD particle mediating an action on a physical object. How can that occur, meaning what is the rational explanation that something that is not only invisible but has no L,W,or H (as I understand dark dark matter - thus the allusion to the concept of god possessing no L, W, or H) be a causative agent for action on a physical object?

That is the nature of the question. Obviously, if dark matter possesses L, W, H then the problem is solved.

[barmar]

Winstonm, on Aug 27 2010, 06:30 PM, said:

I wonder if the powers of observation you describe are the result of observation or mathematics or some combination? I honestly don't know. My question is whether or not mathematics can explain rather than describe.

Scientist have discovered over the centuries that the physical world tends to behave very mathematically. It's uncanny that so many simple formulas can describe observed phenomena.

However, they don't just blindly assume that any particular formula will work. Rather, they hypothesize a formula, make predictions based on it, and then perform experiments to see whether they fit the predictions.

One of the most famous examples was from Einstein's General Theory of Relativity. It predicted that light from stars would be deflected by the gravity of the sun, about twice the amount that Newton's Laws predicted. A number of years later, astronomers measured this deflection during a solar eclipse, and it matched Einstein's theory perfectly.

Since then, many other predictions of Einstein's theories have been verified by observation. Conversely, there have not been any observations that contradict them, so it's hard to justify throwing them out.

But all theories are subject to modification and refinement. Newton's Laws were fine as long as you confined your observations to motion at a small fraction of the speed of light, or within a small gravitational field; Einstein refined them to handle more general cases. It's possible that a theory like MOND could further refine Einstein's theories.

Here's another example. After Uranus was discovered, astronomers tracked its position for several decades, and they noticed that the orbit didn't match the prediction of Newton's Laws. Rather than throw out the math, they asked "What if there's another planet out there, exerting a gravitational force on Uranus?" They did the calculations to figure out where that planet would have to be to cause the difference in the orbit that they observed. Then they looked there, and found Neptune. A similar process was how Pluto was discovered.

So if you have a choice between throwing out a theory that works, or looking for something new that fits in with the existing theory, experience tells us that the latter is the way to go.

[USViking]

Winstonm said:

I wonder if the powers of observation you describe are the result of observation or mathematics or some combination?

A combination. For example telescopes were not available
to Ptolemy, and four dimensional geometry was not either.
Those are just two weapons of the vast arsenal of modern science.

Winstonm said:

I honestly don't know. My question is whether or not mathematics can explain rather than describe.

I believe Galileo said that the Book of Nature is written in the
Language of Mathematics. Another scientist, I forget who, said
that mathematics possesses “unreasonable effectiveness” as
a tool in the study of Nature. Those statements seem to me to
imply both description and explanation, if in fact there is a clear
division between the two.

Winstonm said:

To me, this should be important as the validity of the axiomatic assumptions of the mathematical logic determines the validity of any mathematical proof - it is certainly not the same type proof as observational.

I think proof is in principle unavailable for any scientific theory.

We just have to hope we can arrive at satisfactory explanation
and description of Nature without the need to meet impossible
standards of proof.

Winstonm said:

Who would? Atoms are not visible, yet we know they exist. The only problem I have is with the concept of an OD particle mediating an action on a physical object. How can that occur, meaning what is the rational explanation that something that is not only invisible but has no L,W,or H (as I understand dark dark matter - thus the allusion to the concept of god possessing no L, W, or H) be a causative agent for action on a physical object?

That is the nature of the question. Obviously, if dark matter possesses L, W, H then the problem is solved.

You have skipped ahead of me with OD, what is that?

And L, W and H?- the three spacial dimensions? I have not heard
that spacial dimensionlessness is a requirement of Dark Matter.

[USViking]

USViking said:

Plopping "God" into the issue is an inaccurate and unconstructive rhetorical flourish. 

luke warm said:

are you sure it's inaccurate?

Yes.

luke warm said:

and, on the off chance that it isn't (inaccurate, that is), would it then become constructive?

No.

luke warm said:

...we must assume magical [sic] invisible dust [sic]  that has to be there in order to keep the original theory on target? 

Maybe.

USViking said:

For example, serious Dark Matter theorists assume that although the subject of investigation is neither “magical” nor “dust” it IS invisible. Anyone gotta problem with “invisible”? 

luke warm said:

not me... very hard to falsify an invisible entity

OK, I guess.

[barmar]

You might want to read the book Is God a Mathematician.

[luke warm]

USViking, on Aug 27 2010, 11:54 PM, said:

USViking said:

Plopping "God" into the issue is an inaccurate and unconstructive rhetorical flourish. 

luke warm said:

are you sure it's inaccurate?

Yes.

how can anyone argue with such airtight logic?

Quote

luke warm said:

...we must assume magical [sic] invisible dust [sic]  that has to be there in order to keep the original theory on target? 

Maybe.

i don't believe i said what you are quoting me as saying

Quote

USViking said:

For example, serious Dark Matter theorists assume that although the subject of investigation is neither “magical” nor “dust” it IS invisible. Anyone gotta problem with “invisible”? 

luke warm said:

not me... very hard to falsify an invisible entity

OK, I guess.

okay, so winston's hand-of-God (an invisible entity) thrust holds at least a little water