Why do so many people on YA believe dark energy/matter to be establed scientific fact?

That's exactly what we mean by dark energy and dark matter. The prefix "dark" means we don't know what it is. Something is causing the rate of expansion of the universe to accelerate and that unknown energy is called dark. Again there is mass in the universe we know it's mass because we can detect its presence by its gravity but we can't see it and tell anything about it so it's called dark matter.

Now my question is why do you take what we already know and what we have already said and throw it back in our faces as if it was your own opinion which you had thought of all by yourself?

BTW what you call the phenomena that the hypotheses were proposed to explain is the evidence that dark matter and dark energy exist. We know it's there the key is to find out what it is so we can replace the word "dark" with something more helpful.

Hypotheses is the base of advancement. Jules Verne wrote a book a hundred and fifty years ago about a rocket landing on the moon. You, Who, would have said "What a dumb way of seeing things in the future, I mean, man walking on the moon????"
Besides, who ever mentioned in Yahoo answers that Dark Energy and Dark Matter do exist? We all know they are hypotheses (maybe even they can reach the category of being named theories.)
And who knows.....just like man did walk on the moon and even drove a «car» up there, why can't these Dark hypotheses (Energy and Matter) become a reality.
Remember.....What has been proven to be true today is thanks to what man had hypothesized yesterday.

You've seem to be misunderstanding what the "dark" part of the names means which is that it wasn't observed when it's effects were noted.

As to whether or not they exist, we've been able to map a large amount of unobserved matter by their gravity lensing, we have detectors in deep mines to detect unknown weakly interacting particles and we have detected them just not as many as would've been expected, our estimates of the numbers of rogue planets and brown dwarf stars have gone up which may explain some of the missing mass. Simulations have shown that without dark matter, galaxies are temporary and disperse. We have observed the gravity lensing of galactic halos of dark matter around galaxies but around galaxies that collided, the gravity lensing showed the halos were unimpeded by the collision while the galaxies themselves interacted between the halos which is strong evidence for WIMPs instead of just unseen matter.

With dark energy, the Cassimir effect has been observed. An experiment which used a quantum trick to cool an atomic gas a few billionths of a degree colder than absolute zero showed behaviour as if the atoms were affected by dark energy in a repulsive antigravity effect.

You're putting words in peoples mouth when you say people think it's a scientific fact. Indeed there is no concept of scientific fact period, only observations, hypothesis and theories. You've under estimated the observations and wrongly assessed science as absolute knowledge. I can only surmise that you must do this out of ego to claim everyone else is wrong.

Astronomy in general must make deductive conclusions, because not everything is directly observable. It's well established that our galaxy is a spiral galaxy, but is this a "fact" by your strict criteria? We cannot observe large portions of our galaxy. We can only observe other galaxies, and conclude that the limited region of our galaxy that we can observe more resembles spiral galaxies than elliptical.

Most people who suppose that competing hypotheses can explain the observed evidence as well as dark matter are not acquainted with all the evidence. Sure, "alternative gravity" could explain the anomalous rotation rates of galaxies. Can it explain colliding galaxies where the visible matter clumped together, but appears drawn to two masses that passed by without interacting?

You certainly are getting a lot of answers that miss the point. The "dark" in dark energy/matter may mean "unknown", but these terms do contain implicit assumptions that are taken as fact, which are likely to be wrong.

For dark matter it is the assumption that the movement of matter in a galaxy is governed solely by the force of gravity. Mainstream cosmology neglects electromagnetic forces, i.e. the forces that result from the separation of electric charge in plasma. If these forces were taken into account there would be no need to invent some exotic form of matter. See...

http://www.plasmacosmology.net/
http://www.thunderbolts.info/wp/about/syn/

As for dark energy, this was invented to explain the supposed increasing rate of spacetime expansion. This is NOT an observed fact. It is an inference resulting from the assumption that the redshifts of light from distant galaxies are effectively a doppler effect, implying that galaxies are generally flying away from each other. There is evidence that this assumption is wrong...

As well as stretching out the wavelengths of light, the doppler effect should also stretch out the light curves of quasars (charting their oscillation in luminance), but we find this is not the case: http://phys.org/news190027752.html

It is much more likely that galaxy light loses energy through it's interaction with the matter of the intergalactic medium and the universe is not actually expanding at all. See: http://www.newtonphysics.on.ca/universe/

Also, this documentary will show you how fallible science, especially the field of cosmology, can be: http://www.youtube.com/watch?v=1yTfRy0LTD0&playnext=1&list=PL35A32C6E877FEAC3

Those of us who have been using these terms from the beginning, know that the word "dark" in both cases, was a placekeeper for the adjective "unknown".

At first, it was thought that it was some kind of matter that did not show up in telescopes because
1) it was too dark (for example, MACHOS like dead "black dwarfs" or rogue planets ejected from their planetary systems), or
2) it did not interact with electromagnetism (for example, WIMPS like neutrinos).

However, searches for these kinds of objects showed that
1) MACHOS did exist but they were way insufficient to explain the behaviour of objects subjected to gravity
2) Although neutrinos were finally detected and their mass [almost] accertained, they too are WAY too few to explain the same behaviour.

Thus, the explanation for the behavior of large scale objects, subjected to gravity, falls in two major categories
a) gravity does not behave the way we thought (and part of that was resolved using relativistic gravity - but still not solving the problem completely), or
b) MOND (MOdified Newtonian Dynamics) whereby gravity acts differently over large distances.

Although "b" does not require any additional matter to explain how large systems behave, it does fail when you try to scale it down to "small" systems like the Local Group.

Therefore, scientists are still in the "dark" when they try to explain why systems behave AS IF there was more mass than what we can detect (so far).

In summary, SOME of us do accept that there are still some possibilities that the behaviour COULD be explained by something other than "more matter".

As for "dark energy", there is no doubt in our minds that this "dark" really means "unknown".

Therefore you are correct, these "things" have not been established as facts. However, in the case of dark matter, many people are eliminating what it cannot be. This may lead us to a Sherlock Holmes conclusion: once you have eliminated the impossible, whatever is left, however improbable, must be the truth.

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RE:
Why do so many people on YA believe dark energy/matter to be establed scientific fact?
when they are BOTH hypotheses that explain phenomena in the universe that we cannot explain by our current understanding (and there ARE other hypotheses that explain them)
(for those who dont understand what a hypothesis is I suggest getting a dictionary - its no better than an educated guess)
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I must have stumbled upon a political forum, the blatant fabrications, the question avoidance, distraction techniques, there must surely be politicians afoot.

// "Why do so many people on YA believe dark energy/matter to be established scientific fact?" //.

Beats me! I can only imagine, they are misinformed or that they follow like sheep their misinformed peers.
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Neither DM nor DE have been confirmed,( today... you can't read a dozen words into their wikipedia descriptions without seeing the word hypothetical.) anyone who thinks they have been confirmed is misinformed or deluded. (or awaiting a Nobel prize. )
Even the use of the words - Matter and Energy are presumptions.

ADDITION :
Both arose because : Observation disagrees with theory; "that much is known."

Both Dark Matter and Dark Energy, were hypothetical suggested explanations toward resolving those observational contradictions. Both are currently beyond the understanding of physics.
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I could end this now : both Dark Energy and Dark Matter are small fry.
Let me give you guys a hint.
Ask yourselves this :
Dark matter is estimated to constitute 84.5% of the total matter in the universe.
( just in case you guys haven't twigged : that's 84.5% of total universal gravitation.)
Why? with such an universal abundance; can we barely find any trace by experiment and / or observation : of dark matter in our own Solar system?
Thinkonit : or at least make the effort to wake up.
Good luck.
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All the best.

Actually, in the case of dark matter, it basically has to exist. Either there's mass that we can't see, or everything we know about gravity and mass is wrong. The Milky Way's rotation curve should *not* be flat. Not even close.

As for dark energy, I think it's the poorly understood nature of the phenomenon. We're so baffled as to what it is that "dark energy" has become more of a placeholder term than anything else.

I'm sorry you don't appear to understand how science works...

The rotation curves of galaxies are non-newtonian. It was suggested that non-baryonic matter could cause this. If this was the case it would also cause lensing, so we went looking for it and found it, which suggests that we were correct about Dark Matter. Further observational experiments have confirmed it's existence. BTW we don't really know what Dark Matter is, but we know what it isn't

The evidence for Dark Energy isn't as tight as yet as the evidence for Dark Matter, but this is because the primary evidence for Dark Energy was only discovered about a decade or so ago whilst that for Dark Matter is considerably older. We still need some more observations to really nail dark energy down.

BTW - In science nothing is truly proven 100% and when we think we are wrong we correct our theories. Dark Matter might be wrong, Dark Energy might also be wrong. Although the chances are quite small.