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dark matter mapped (pg. 2)
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| Omega_M |
| quote: | Originally posted by DJ Shibby
Hm... actually, I don't.
where exactly do the popular experts get their qualifications?
Oh... that's right, their models are mostly based on Einstein's model of relativity, in which he himself said that our theories are guesses that attempt poorly to mold to what is actual reality and not vice versa.
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Shall I let you in on a secret ? We will never be able to understand the reality ever. The entire science from ancient times up to this point is based on models which "depict" the reality. Our understanding of this Universe is based on the universe we see with our eyes and interpret with our brains. Our explanations of how it works are all in the mind. We keep refining our explanations by putting forward new theories. It does not mean that the universe was once Newtonian and now it is based on Einstein's relativity. Our understanding has now changed and not the other way round.
We make observations and our mind creates models based on fundamental assumptions, which generate results consistent with the observations. Constants and parameters in the models are adjusted to fit the observations. We cannot explain why for example a particular constant has a particular value. It simply has, because it fits the data, and also seems to make predictions which are proved correct on further experimentation. Why is the speed of light in vacuum 3 x 10^8 m/s ? A fundamental answer to this question will yield a few more fundamental constants, but the answer will never be satisfactory
New theories evolve from old ones. For example, discrepancies in the predictions of existing theories and the observed data on how bodies radiate heat, led to the development of quantum theory. The inability of any existing theory to explain why speed of light was constant and not dependant on a frame of reference led to the development of theory of special relativity. Einstein was at the right place at the right time. If not him, someone else would have put forth a similar theory. Scientific thought had matured to a point where we could theorize the universe with that level of complexity.
It is absurd to say that we need to go back and correct errors in Einstein's theories. There are no errors so long as the theory is able to make predictions and observations are made which are consistent with the calculations. If dark matter predictions are consistent with his theory, the there is dark matter because nobody is smart enough to come up with an alternative theory. If we as human beings have matured enough, then we will put forth a new theory which will explain the Universe in a better way. But evolution of modern scientific thought is such that past theories are proved to be special cases of the new theory. Newton's gravitation is a special case of Einstein's gravitation when the speed of objects is much less compared to the speed of light. Both theories will yield identical answers to problems of slow moving bodies.
Physics is based on solid experimentation. It is not hypothetical or empirical. There are theories which make predictions which are impossible to test by experimentation. Like the big bang theory, for example. But the theory was sophisticated enough to explain side effects which were observed. That was how they proved the Big Bang theory. And the guys who helped make the precise measurements of the "side effect" (although this is not the best way to describe it, but nevertheless) were awarded the 2006 noble prize in physics.
If you want to be critical of scientific theories then you need to be a scientist and state valid scientific reasons why you think they are wrong and point out the errors in the past theories. Mere speculations based on belief are not enough. |
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| Omega_M |
The first post in this thread is fascinating. Dunno, how I missed that. One interesting article I did read was about the image of the Universe's first objects !! And here it is !
The right panel is an image from NASA's Spitzer Space Telescope of stars and galaxies in the Ursa Major constellation. This infrared image covers a region of space so large that light would take up to 100 million years to travel across it. The left panel is the same image after stars, galaxies and other sources were masked out. The remaining background light is from a period of time when the universe was less than one billion years old, and most likely originated from the universe's very first groups of objects — either huge stars or voracious black holes. Darker shades in the image on the left correspond to dimmer parts of the background glow, while yellow and white show the brightest light
Read the entire article here |
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| Q5echo |
| quote: | Originally posted by Omega_M
That was how they proved the Big Bang theory. |
well, not trying to be smart ass, but why is it still called a theory?
what the guys you're talking about did was reinforce the current "cosmological paradigm" within the community. |
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| Omega_M |
| quote: | Originally posted by Q5echo
well, not trying to be smart ass, but why is it still called a theory?
what the guys you're talking about did was reinforce the current "cosmological paradigm" within the community. |
Well I guess it really isn't a theory then. It's a fact.
Theories and assumptions within the existing "cosmological paradigm" which have been accepted as true should, for all practical purposes, be considered as facts and not simply reinforcements of the current paradigm because at this moment of time, the current paradigm is the accepted description of reality.
In the strictest sense, if you consider a larger span of time, then they may not be facts. There is a possibility that these "facts" will be modified or rejected. For example, Euclidean "axioms" of geometry were proved to be false for certain cases. In fact, relativity is based on non-euclidean geometry. |
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| Q5echo |
| IOW, no better scientific explaination for the expansion itself, but the origin is another question? |
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| Omega_M |
| Of course not. What makes you think I'm saying it's another question ? Besides, proof of big bang does not mean that all the questions about the origin have been answered. |
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| Q5echo |
| quote: | Originally posted by Omega_M
Of course not. What makes you think I'm saying it's another question ? Besides, proof of big bang does not mean that all the questions about the origin have been answered. |
no no no. i should have said "it's origin" [Big Bang] by itself.
as we understand the expansion so well now, the origin of the Big Bang becomes the question, hence it still being regarded as theory.
thats what i understood (maybe wanted to understand) your post to mean in other words. |
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| Renegade |
| quote: | Originally posted by DJ Shibby
I think that our current theories are unable to determine yet what actually happens out there in the void, and we keep building on TOP of old theories, instead of taking steps backwards to rectify errors. The reason we can't do this is most likely because our system of arithmetic itself may be the root of the problem, disallowing the cohesion of absolute information and theoretical inquery.
So yeah... we can't actually ascertain the weight of galaxies and solar systems, so we sloppily make up a variable, "dark matter", to encompass everything that we don't yet understand or doesn't fit correctly into our models. |
First of all "dark matter" is not just a "variable" that has just been arbitrarily "made up" by astrophysicists to compensate for their "sloppy" arithmetic. The cohesion of galaxies indicates that they are bound by a gravitational force that far exceeds what we would expect given the amount of baryonic matter within them (I believe that there is only about 4% of the baryonic matter necessary to sustain the sort of structures that galaxies arrange themselves in). If this is the case, then there are basically two options: either our theory of gravity is wrong, or there is some unseen element that accounts for the missing gravitational force.
You seem to favour the first option. That is, that either our assumptions about the gravitational constant are wrong or that gravity somehow behaves differently on scales as large as those of galaxies (which would constitute sloppy arithmetical padding were it to be a alternative seriously advanced by astrophysicists). When I say "wrong" here, by the way, I'm not talking about being wrong in our assumptions about gravity by a few minor degrees: I'm talking about being wrong by a factor of about 25. Given how well we can use our current models of gravity to explain the behaviour of bodies on virtually all scales - from the terrestrial to the celestial - the idea that our assumptions about the strength of the gravitational force could be wrong by such a huge factor is simply inconceivable.
I understand from other discussions we've had that you fancy yourself as something of a Popperian epistemologist, but your assumption that we could be so fundamentally mistaken about the nature of gravity simply flies in the face of basically all empirical data. If you're going to seriously advcance the idea that our arithmetic concerning gravity is so fundamentally flawed, then I'd be interested to hear how it is you think that we can accurately predict the orbital paths and speeds of all orbiting bodies (tiny perturbations in these predictions allowed us to postulate the existence of Pluto before it was discovered - or was that just a "sloppy" variable too?) or send probes successfully to Neptune. Perhaps our theory of gravity could turn out to be wrong, but there is no possible way that it could turn out to be wrong enough to account for the stability of galaxies without introducing some previously unknown element.
As for dark matter itself, its introduction to the equation says nothing about its nature. We don't know whether it's baryonic matter (almost certainly not), whether it is affected by the electromagnetic or nuclear forces (most likely not) or how much of it - in terms of volume - actually exists (we have no idea). At the moment it's still just a theoretical particle, but then so were all other particles at one point: everything on the scale of the molecule, down to the atom, to the baryons and leptons, all the way to level of the quark were all just abstract equations before their existence could be empirically demonstrated in a laboratory setting. I suspect that in the next decade or so, exactly the same will be made true with regards to so-called "dark" matter. |
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| DJ Shibby |
| quote: | Originally posted by Renegade
First of all "dark matter" is not just a "variable" that has just been arbitrarily "made up" by astrophysicists to compensate for their "sloppy" arithmetic. The cohesion of galaxies indicates that they are bound by a gravitational force that far exceeds what we would expect given the amount of baryonic matter within them (I believe that there is only about 4% of the baryonic matter necessary to sustain the sort of structures that galaxies arrange themselves in). If this is the case, then there are basically two options: either our theory of gravity is wrong, or there is some unseen element that accounts for the missing gravitational force.
You seem to favour the first option. That is, that either our assumptions about the gravitational constant are wrong or that gravity somehow behaves differently on scales as large as those of galaxies (which would constitute sloppy arithmetical padding were it to be a alternative seriously advanced by astrophysicists). When I say "wrong" here, by the way, I'm not talking about being wrong in our assumptions about gravity by a few minor degrees: I'm talking about being wrong by a factor of about 25. Given how well we can use our current models of gravity to explain the behaviour of bodies on virtually all scales - from the terrestrial to the celestial - the idea that our assumptions about the strength of the gravitational force could be wrong by such a huge factor is simply inconceivable.
I understand from other discussions we've had that you fancy yourself as something of a Popperian epistemologist, but your assumption that we could be so fundamentally mistaken about the nature of gravity simply flies in the face of basically all empirical data. If you're going to seriously advcance the idea that our arithmetic concerning gravity is so fundamentally flawed, then I'd be interested to hear how it is you think that we can accurately predict the orbital paths and speeds of all orbiting bodies (tiny perturbations in these predictions allowed us to postulate the existence of Pluto before it was discovered - or was that just a "sloppy" variable too?) or send probes successfully to Neptune. Perhaps our theory of gravity could turn out to be wrong, but there is no possible way that it could turn out to be wrong enough to account for the stability of galaxies without introducing some previously unknown element.
As for dark matter itself, its introduction to the equation says nothing about its nature. We don't know whether it's baryonic matter (almost certainly not), whether it is affected by the electromagnetic or nuclear forces (most likely not) or how much of it - in terms of volume - actually exists (we have no idea). At the moment it's still just a theoretical particle, but then so were all other particles at one point: everything on the scale of the molecule, down to the atom, to the baryons and leptons, all the way to level of the quark were all just abstract equations before their existence could be empirically demonstrated in a laboratory setting. I suspect that in the next decade or so, exactly the same will be made true with regards to so-called "dark" matter. |
I'm saying that you believe that there are only two options, when there are most likely millions of options depending on how you approach the problem and with which theories you use.
I'm also saying (kind of) what you're saying -- that this research will probably lead to us discovering another unseen variable or element of the universe that we currently can't see. |
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| DJ Shibby |
| quote: | Originally posted by Omega_M
Physics is based on solid experimentation. It is not hypothetical or empirical. |
Are you ing kidding me? :rolleyes:
The problem with people today is that they put so much faith in the current models that they don't realize that there are any number of similar models that could work just the same but which would answer other problems. We also assume that we can only use one model, building only upon the shoulders of giants. It's a weakness that one day we'll realize and find solutions to.
Also, anyone can be a scientist, so don't throw elitist bull at me.
If you can perform experiments and come up with (often) testable ideas then you can be a scientist.
The problem is that our modern world (read: us, our tendency for habit and comfort) has turned us into nonthinking drones lacking creativity and common sense. We are sent to school so that we can learn the exact same methods and theories that have been determined to be "true", we get out of school and work as nonthinking drones in labs.
I'm reading a chemistry book at the moment from 1902; it's fantastic. The best part is that I can see how people thought and felt about science -- alchemy and chemistry -- before the big world wars and before the population boom and before the new model of chemistry arose (READ: NEW as in... the Greeks thought it up and our backwards christian world delegated its logical genius to the backburner for 2000 years...). Yeah, I'm talking about atoms.
It's also cool because it's the critical transitional period between romantic magic and solid scientific fundamentalism, objective observations fit into the ephemeral models we build to explain those phenomena.
The only thing a person needs to be a good scientist is to question everything. |
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| Lilith |
Actually I saw a doco on radiation the other day on telly, about the re-evaluation of the effects of things like Chernobyl which had a fairly convincing arguement in terms of a lot of the hazards being 'overstated' by fairly much all the scientific community.
http://news.bbc.co.uk/1/hi/sci/tech/5173310.stm
Sadly doesnt exist on google.vids or anything yet.
Aside from that, rest of the thread may as well be in chinese to me.
And no Shibby, not everyone can be a scientist. Especially me! |
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