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justintime
BANNED
382 Posts |
 Posted - 10/08/2011 : 09:58:45 [Permalink]
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Originally posted by Sebastian
As far as I know, no-one has discovered a single atom or particle of this invisble matter or energy, called dark matter for good reason.
Aren't we stretching credulity a bit here? One might as well believe in the existence of a God.
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I second Sebastian position.
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive.
Though the theory of dark matter remains the most widely accepted theory to explain the anomalies in observed galactic rotation. Why?
Have the scientific body conveniently moved away from invisible matter to alternate theories where visibility or actual proof of existence is not necessary.
Alternative theories have been proposed to explain these observations without the need for a vast amount of undetected matter.
Gravitational constant grows at different scales, then dark matter is not needed to explain galactic rotational curves.
Now quantum gravity can produce unifying theories such as.
The Theory of Everything, SuperStrings Theory, the M-Theory.
Aren't we stretching credulity a bit here? One might as well believe in the existence of a God.
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Kil
Evil Skeptic
USA
13476 Posts |
Posted - 10/08/2011 : 10:28:21 [Permalink]
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justintime:
I second Sebastian position. |
Of course you do. More bait...
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Uncertainty may make you uncomfortable. Certainty makes you ridiculous.
Why not question something for a change?
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Tim Thompson
New Member
USA
36 Posts |
 Posted - 10/08/2011 : 18:24:18 [Permalink]
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Originally posted by Sebastian (9/27/2011 19:36:26)
Originally posted by Tim Thompson (9/24/2011 10:40:37)
The failure to see something that you should see constitutes direct & positive evidence of non-existence. This is firmly rooted in the idea of inference from observation, which is the single most fundamental principle throughout the entire edifice of science. This is why I choose to insist that you, and not we, have a semantic problem. You appear to have chosen to re-define the word "evidence" to suit your own personal prejudice. Of course you can always do that for yourself, but it puts you firmly at odds with the entire suite of disciplines that constitute the natural sciences.
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This is an interesting statement which reveals your confusion. It is quite true that the failure to see something that one should see does indeed constitute direct and positive evidence of non-existence for all every-day activities of homo sapiens from the time we separated from our distant ape-like relatives. But I thought we were talking about science.
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I fail to see why the point is not just as valid in science and assert that this is indeed the case. In science it is certainly true that the failure to see something that you should see constitutes direct and significant evidence that the thing(s) in question in fact do not exist.
Originally posted by Sebastian (9/27/2011 19:36:26)
There is also the problem of just who it is who determines what we should or should not see in a particular set of circumstances? This is why we have developed the scientific method, in order to achieve a useful degree of certainty about what we should and should not see, and in what circumstances.
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Easy. Consider this: The White Dwarf Cooling Sequence of the Globular Cluster M4 and pay specific attention to figure 1 of that paper. In this figure the dashed lines represent the 50% recovery limit, which means that above those dashed lines, the Hubble Space Telescope is sensitive enough to detect more than 50% of the plotted objects, and below the dashed lines, the telescope is not sensitive enough to detect as many as 50% of the plotted objects. Moreover, the sensitivity of the telescope falls off rapidly below the dashed lines. You can see (especially in the high resolution version) that the count of black plotted points near the bottom of the figure drops off significantly before the dashed lines. This drop off is not due to an inability to see, because we are above the sensitivity limit for the telescope, so it must be the case that these objects are not seen because they are not there to see. These are white dwarf stars in globular cluster M4 and the failure to detect dim white dwarfs, under conditions where they should have been detected by the instruments used, is significant. It suggests that the coolest white dwarfs in the cluster are now being observed, and in this case coolest means oldest. So if we apply a cooling model to the white dwarfs observed, we can determine from the cooling time how old the cluster is. It is significant as well that the derived white dwarf cooling age is consistent with the age derived from the main sequence turn-off method.
This is a case where it is obvious that the failure to detect something that should be detected is significant evidence for their non-existence, in this case the non-existence of cool/old white dwarfs that should still be bright enough for HST to detect.
You have said nothing to contradict in any way the point that I made before:
Originally posted by Tim Thompson (09/17/2011 09:36:54)
When Zwicky first introduced the problem of "missing mass" (Zwicky, 1933; Zwicky, 1937; the latter translation into English was the first time many astronomers became aware of the issue) he had no reason to believe it was not ordinary matter; gas, dark clouds of dust, dim stars, planets & etc. And there is no single moment when suddenly & without warning astronomers exclaimed "it must be non-baryonic dark matter". It just slowly dawned on astronomers as they continued to look and did not see. In this case, the context was set by technology. If you look for something and do not see it, even though you know it lies well within the capabilities of your technology, then the failure to detect it is significant, and increases in significance as time & technology advance with continuing invisibility of that which should be seen. The advent of radio & infrared astronomy is particularly damaging to baryonic dark matter, since cooler stars & especially clouds of dust & gas will stand out clearly at theses wavelengths, where they would be truly invisible to Zwicky. Likewise, X-ray astronomy reveals hot gas & low-mass stars (the latter, being fully convective, are somewhat more prone to flare than solar-type stars and so become evident as X-ray flare sources). In the case of our own Milky Way, specific searches for low mass stars have clearly demonstrated that they cannot be the ultimate source of dark matter (e.g., Hubble Space Telescope, 1994).
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The "who" you question above is the scientific community itself. The original papers & reports present the scientific arguments, including the limitations of technology, and they are open to examination by the community. It is not a subjective process; the elements of science & technology are objective, constitute valid, objective limits on observation. If you know that object X, whatever it is, should lie within the bounds of detectability established by technology, and you don't see it, then you can confidently assert that object X in fact is not there to see. It's reasonable, it's objective, and it is wholly valid science.
Originally posted by Sebastian (9/27/2011 19:36:26)
We have a long way to go before we confirm the existence of dark matter. It's quite likely we may never confirm its existence.
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I disagree. I think that the existence of dark matter has in fact already been confirmed, you are just not aware of the real scope of the science involved.
Originally posted by justintime (10/08/2011 09:58:45)
Alternative theories have been proposed to explain these observations without the need for a vast amount of undetected matter.
Gravitational constant grows at different scales, then dark matter is not needed to explain galactic rotational curves.
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Alternative theories have indeed been suggested. But all of those alternative hypotheses are subject to verification by observation, as one would expect for any scientific hypothesis. They have failed the test; none of the alternatives suggested can explain the full range of observations that dark matter explains, so they are inferior in explanatory value. They are still being testes, there are still plenty of papers on the alternatives, they are definitely not being ignored. They just don't work. So it's quite natural that the scientific consensus would concentrate on the practical weight of that which works, and that is non-baryonic dark matter.
Originally posted by justintime (10/08/2011 09:58:45)
Have the scientific body conveniently moved away from invisible matter to alternate theories where visibility or actual proof of existence is not necessary?
Aren't we stretching credulity a bit here?
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Not at all. As you can see from the explanation above, it is credulity that drives the consensus towards dark matter in the first place, specifically the credulity of the practical; scientists, like any one else, will always prefer the options that work best in practicality, and in this case that option is non-baryonic dark matter.
You can't argue reliably without knowing something about the science of dark matter. I recommend Dark Matter: A Primer by Garrett & Duda, Advances in Astronomy, 2011; or Dark Matter: The evidence from astronomy, astrophysics and cosmology by Matts Roos, January 2010. These are general reviews, but will reference other more specific papers. There is in fact a huge body of observational evidence that is best explained as the observational effect of dark matter. |
The point of philosophy is to start with something so simple as not to seem worth stating, and to end with something so paradoxical that no one will believe it. -- Bertrand Russell |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/08/2011 : 20:12:11 [Permalink]
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Originally posted by justintime
I second Sebastian position.
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive.
Though the theory of dark matter remains the most widely accepted theory to explain the anomalies in observed galactic rotation. Why?
Have the scientific body conveniently moved away from invisible matter to alternate theories where visibility or actual proof of existence is not necessary.
Alternative theories have been proposed to explain these observations without the need for a vast amount of undetected matter.
Gravitational constant grows at different scales, then dark matter is not needed to explain galactic rotational curves.
Now quantum gravity can produce unifying theories such as.
The Theory of Everything, SuperStrings Theory, the M-Theory.
Aren't we stretching credulity a bit here? One might as well believe in the existence of a God. |
Well, it's obvious that you ignored everything in this thread except the two lines of Sebastian's that you quoted. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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justintime
BANNED
382 Posts |
Posted - 10/09/2011 : 15:12:12 [Permalink]
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Tim Thompson this is really something for Sebastian to respond to. But the whole theory behind missing mass which hypothetically became dark matter was necessary because of some anomalies discovered by Zwicky.
| "Zwicky inferred that there must be some non-visible form of matter which would provide enough of the mass and gravity to hold the cluster together." |
Which then needed some invisible missing mass and Vola!!! It was dark matter
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive. But it is vital to explain the anomalies in observed galactic rotation and hence its inclusion, even though no direct evidence of its existence or any understanding of its nature remains elusive.
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| Edited by - justintime on 10/09/2011 15:12:45 |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/09/2011 : 17:32:43 [Permalink]
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Originally posted by justintime
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive. |
That's true about a lot of things. So what? Bold fonts and italics don't make your point any clearer. |
- Dave W. (Private Msg, EMail)
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Dave W.
Info Junkie
USA
26020 Posts |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/22/2011 : 16:23:05 [Permalink]
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The Status of Dark Matter:Astrophysically, there's got to be some type of dark matter out there, and it needs to be about five times as abundant as the normal, baryonic matter we have. The indirect evidence is overwhelming. If you try to build a theory without dark matter, you simply have to throw out a whole suite of very well-tested and verified physics, and you still cannot explain all the observations detailed above. |
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justintime
BANNED
382 Posts |
Posted - 10/24/2011 : 15:27:34 [Permalink]
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Originally posted by Dave W.
The Status of Dark Matter:Astrophysically, there's got to be some type of dark matter out there, and it needs to be about five times as abundant as the normal, baryonic matter we have. The indirect evidence is overwhelming. If you try to build a theory without dark matter, you simply have to throw out a whole suite of very well-tested and verified physics, and you still cannot explain all the observations detailed above.
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As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive. |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/24/2011 : 18:27:30 [Permalink]
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Originally posted by justintime
As important as dark matter is believed to be in the cosmos, direct evidence of its existence and a concrete understanding of its nature have remained elusive. |
If I see a neighbor's garbage can out on the street on a garbage pick-up day, then even without direct evidence or a concrete understanding of what's in the can, I can still conclude that it's most likely to be trash. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
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Sebastian
New Member
44 Posts |
Posted - 10/31/2011 : 21:18:20 [Permalink]
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Sorry for not responding for a while. I've been on holiday, trekking in Nepal. No, I didn't climb Mt Everest. There's too much congestion on that mountain, people waiting below the summit for others to descend so they can move up. The Hillary Step appears to be the congestion point, only wide enough for one line of trekkers.
I'll continue with this quote from Tim Thompson.
| I fail to see why the point is not just as valid in science and assert that this is indeed the case. In science it is certainly true that the failure to see something that you should see constitutes direct and significant evidence that the thing(s) in question in fact do not exist. |
Tim,
By 'see' I presume you mean 'detect by whatever means'. If so, of course I agree. It is reasonable to assume that what has not been detected does not exist in any meaningful manner. We can discuss the possibility of the existence of such undetected events or substances. We can imagine all sorts of scenarios ad infinitum.
However, until we have captured or detected the imagined particle, substance or force, it cannot be said to exist.
The mathematical predictions of Paul Dirac that antimatter should exist is a very good analogy.
The notion from Dave W that Paul Dirac was reluctant to publish his theories regarding antimatter because he was too 'shy', is really a bit ludicrous. Being both an excellent Physicist and Mathematician, unlike Einstein, Dirac was reluctant to publish his mathematical basis for the existence of antimatter because he was aware of the danger that pure maths could on occasions lead to absurdity.
I get back to the fundamental principle of all science; evidence that can be verified, falsified, examined repeatedly, pulled apart and studied from different perspectives.
Even after all these processes have been carried out, sometime over several generations, we can still be wrong.
This why I consider one of the most meaningful tests of any scientific theory is its practical application.
For example, the theories of Quantum Mechanics are in many respects absurd. They imply instantaneous communication over vast distances at 'greater than' the speed of light. They imply a weird sort of prescience or prediction of the future whereby a quantum of light (or a photon) seems to know the path it's going to take before it takes it.
Eistein wouldn't have a bar of it. He thought it ridiculous.
So why do we accept the modern theories of Quantum Mechanics? BECAUSE THEY WORK.
That we could predict from our existing theories that a certain amount and type of matter and energy could or should exist despite it being currently undetectable, is not in itself unprecedented, astounding or totally unbelievable.
It's the SHEER QUANTITY of that invisible stuff that rings alarm bells. 95% OF THE STUFF OF OUR UNIVERSE IS UNDETECTABLE? |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 10/31/2011 : 21:34:25 [Permalink]
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Originally posted by Sebastian
The notion from Dave W that Paul Dirac was reluctant to publish his theories regarding antimatter because he was too 'shy', is really a bit ludicrous. |
It's been mentioned by biographers.| Being both an excellent Physicist and Mathematician, unlike Einstein, Dirac was reluctant to publish his mathematical basis for the existence of antimatter because he was aware of the danger that pure maths could on occasions lead to absurdity. |
Just nevermind that (as has already been discussed in this very thread) that there are typically many factors which go into these sorts of decisions. You go ahead and run with the idea that just one thing was the cause of Dirac's decision.| I get back to the fundamental principle of all science; evidence that can be verified, falsified, examined repeatedly, pulled apart and studied from different perspectives. |
And what's wrong with the indirect evidence that we have in hand, which has been tested, verified, examined, deconstructed and re-tested all over again and has not yet met a test which falsified it?| Even after all these processes have been carried out, sometime over several generations, we can still be wrong. |
Which, if taken to its extreme, suggests that we should never settle on anything, not even for an instant. We might find out we were wrong later, after all.| This why I consider one of the most meaningful tests of any scientific theory is its practical application. |
And Dark Matter is a practical, functioning solution to many questions about the universe. To paraphrase you, IT WORKS.| It's the SHEER QUANTITY of that invisible stuff that rings alarm bells. 95% OF THE STUFF OF OUR UNIVERSE IS UNDETECTABLE? |
Your incredulity isn't evidence of anything. Einstein (as you noted) was incredulous about quantum physics, and he was wrong. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dr. Mabuse
Septic Fiend
Sweden
9687 Posts |
Posted - 11/01/2011 : 07:02:13 [Permalink]
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Originally posted by Sebastian
It's the SHEER QUANTITY of that invisible stuff that rings alarm bells. 95% OF THE STUFF OF OUR UNIVERSE IS UNDETECTABLE?
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When push come to shove, you're making an argument from incredulity. While agreeing with the point that dark matter exist because we can measure its effects.
I think you need to go back and re-think your position on the matter.
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Sebastian
New Member
44 Posts |
Posted - 11/01/2011 : 19:17:47 [Permalink]
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I'm getting a strong sense of a lack of clear thinking from some of you people. Let's examine some of Dave W's comments.
1. | And what's wrong with the indirect evidence that we have in hand, which has been tested, verified, examined, deconstructed and re-tested all over again and has not yet met a test which falsified it? |
It seems that Dave is confused about the difference between direct and indirect evidence. Indirect evidence is an inference or implication. By its very nature it cannot be verified or falsified except in a fictitious sense, as in the context of a novel where each character behaves in a credible manner.
2. In response to my statement: "Even after all these processes have been carried out, sometimes over several generations, we can still be wrong."
Dave W replies, | Which, if taken to its extreme, suggests that we should never settle on anything, not even for an instant. We might find out we were wrong later, after all. |
Confusion again.There is always a good reason to settle on something (such as a well-tested theory) if it continues to work flawlessly and is instrumental in the production of the goods and service which we use for our survival and activities on this planet.
It's only when theories are found to be inadequate or not sufficiently accurate for certain purposes that we have to rethink them. Newtonian Mechanics is still valid for many tasks on the surface of our planet involving relatively short distances.
| And Dark Matter is a practical, functioning solution to many questions about the universe. To paraphrase you, IT WORKS. |
Just like the concept of God, or an intelligent creator works? Just as a character in a novel works? It seems we have a different understanding of the meaning of practical.
It's seems that Dr. Mabuse is just as confused as Dave W.
When push come to shove, you're making an argument from incredulity. While agreeing with the point that dark matter exist because we can measure its effects.
I think you need to go back and re-think your position on the matter. |
Firstly, all questioning begins with some degree of incredulity. When the question is satisfactorily answered the incredulity ceases.
Secondly, I've never agreed that Dark matter exists because we can measure its effects. How on earth could you make such a deduction from what I've written so far?
My position is clear. That which exists can be measured or detected. That which cannot and/or has not been measured or detected cannot be claimed to exist, although one may speculate that it may exist, which is the case with Dark matter and energy.
When a group of scientists have to invent the existence of an absolutely enormous quantity of totally invisible matter in order to preserve its current theories, then warning bells should be ringing, especially on a skeptic site such as this. This is a skeptic site, isn't it?
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Sebastian
New Member
44 Posts |
Posted - 11/01/2011 : 19:57:07 [Permalink]
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The confusion deepens. What is Tim Thompson trying to say in the following quote?
| The "who" you question above is the scientific community itself. The original papers & reports present the scientific arguments, including the limitations of technology, and they are open to examination by the community. It is not a subjective process; the elements of science & technology are objective, constitute valid, objective limits on observation. If you know that object X, whatever it is, should lie within the bounds of detectability established by technology, and you don't see it, then you can confidently assert that object X in fact is not there to see. It's reasonable, it's objective, and it is wholly valid science. |
He seems to be saying that it is reasonable, objective and wholly valid science to assert that Dark Matter does not exist. If so, I would agree with him on that point.
However, I also believe in lateral thinking, outside the box. Whatever can be imagined may eventually be proved to exist, even a God of sorts. We should not exclude any idea however unlikely, in the absence of a better and more effective explanation.
I'm certainly not excluding the notion that 95% of our universe is currently invisible by its very nature. In fact I'm giving the idea a fair amount of publicity in this thread.
I just think the notion is 'a bit over the top', to put it mildly. I think I could find more reason to believe in Intelligent Design. But I could be wrong.
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Skepticism about the Big Bang
