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# Substitute to Dark Matter?

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Goodbye, ob.

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Originally posted by: oblivion

Ah. Showing his real age now. Good riddance.

Tormod

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I have been thinking about what could make the universe accelerate and the best thing I could come up with Is that it must be a repusive gravitational force. I have come to this conclusion because almost every thing has an opposite. for example, the magnetic poles,light and dark,direction,matter and anti matter and the list goes on. But if you consider matter and and anti matter as being the same, in the sence that it is matter that we can see by bouncing light off of it. Then dark matter is the opposite of matter and anti matter, and then would possibly have a negative gravitational effect on all other matter.

But there is one thing that does not work out with this. Why does light energy not get repulsed by the dark matter. If matter and energy are the same then all forms of energy should get repulsed by this dark matter. Does anyone have any info that can help me out with this problem?

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Wavelength,

I don't understand the concept of an accelerating universe. Do you mean the expansion of the universe?

If so, here is a good link:

"Is the universe expanding faster than the speed of light?"

http://curious.astro.cornell.edu/question.php?number=575

Don't know if it answers your light energy question but it's an article about the expansion of the universe, with some good links too.

Tormod

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I think wavelength is talking about the findings - starting around 1998 IIRC - that the expansion of the Universe is accelerating (speeding up) instead of decelerating (slowing down). Gravity between all the matter in the Universe counteracts expansion, and it was thought for decades that gravitational attraction would cause expansion to slow down over time (possibly stop, and reverse, leading to a "gnab gib" or "big crunch"). But somewhere around 1998 findings related to Type IA supernovae indicated that expansion was accelerating. Scientists started resurrecting Einstein's cosmological constant (a balancing "fudge factor" he had added to his equations of General Relativity to make the Universe static), but giving it slightly different values, to help try to explain the findings. I've not kept track of it for some time so I can't comment on what the latest expanations offered are.

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Originally posted by: wavelength?

I have come to this conclusion because almost every thing has an opposite. for example,... light and dark,

Dark is the ABSENCE of light. It is NOT the opposite of light. It is strictly a relative relationship. What would be considered DARK in one relationship would be LIGHT in another. A cloudless full moon night would be dark compared to the day, but light compared to bottom of the ocean.

But there is one thing that does not work out with this. Why does light energy not get repulsed by the dark matter. If matter and energy are the same then all forms of energy should get repulsed by this dark matter. Does anyone have any info that can help me out with this problem?

One of the problems inherent in scientific research is choosing words to describe findings that do not correlate to estblished venacular.

You confusion with dark being an opposite of light rather than a relative presence of it, would lead to confusion when the term "darK' is then applied as a modifier of the word "energy" to define a particular type being researched. It could have been named "saehfoshf matter", but "dark matter" had a compelling ring. Plus it had a descriptive quality as it is postulated that it is some form of matter that is not visible.

But is is NOT "dark" matter as an opposite to "light matter".

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I think wavelength is talking about the findings - starting around 1998 IIRC - that the expansion of the Universe is accelerating (speeding up) instead of decelerating (slowing down). I've not kept track of it for some time so I can't comment on what the latest expanations offered are.

Currently the most commonly agreed explanation I believe is "Dark Energy". Or perhaps I should say is CALLED Dark Energy. I say "called" because it is more a name to allow a target for research. As in "If there was this Dark Energy...".

NASA has a litte ditty about it at:

http://universe.gsfc.nasa.gov/science/darkenergy.html

Or Wikipedia

"In cosmology, dark energy is a hypothetical form of energy which permeates all of space and has negative pressure resulting in an effective "repulsive gravitational force". Dark energy may account for the accelerating universe as well as a significant portion of the mass in the universe. Two proposed forms of dark energy are the cosmological constant and quintessence, where the former is static and the latter is dynamic. Distinguishing between the two requires high precision measurements of the expansion of the universe to see how the speed of the expansion changes over time. Making such measurements is a topic of current research."

http://en.wikipedia.org/wiki/Dark_energy

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I also posted an article about dark matter and dark energy recently:

http://www.hypography.com/article.cfm?id=34246

Tormod

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Originally posted by: Tormod

I also posted an article about dark matter and dark energy recently:

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Tormod

Which is why I posted (before we got off on an Oblivian sidetrack)

Originally posted by: Freethinker

Thanks for the new article Tormod.

"More to the universe than meets the eye"

It brings up a qquestion that perhaps some reader might be able to help me with.

Especially with this possible resolution of Dark Matter/ Dark Energy, are we coming around to the "ether" again?

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Ah...that's what I get from not reading up before I post. Sorry.

Tormod

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• 2 months later...

I found an interesting article about dark matter possibly affecting the Pioneer spacecraft as they leave the solar system. It appears that some unknown force is acting on them to put them where we would not expect them to be. Dark matter is just one of many possible causes, but this seemed the most appropriate place to post the link.

http://www.guardian.co.uk/life/science/story/0,12996,1302722,00.html

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This has actually been know for some years now. Here's an article from New Scientist (published on another site...):

Distant Spacecraft Seem To Be Showing No Respect For The Laws Of Physics

http://www.mufor.org/antigrav4.html

I don't know too much about the physics of hurling spacecraft around, but I suspect we're not about to find a new force. I rather think it will turn out that we don't know enough about the forces as they are. This is, after all, the first time ever that we can observe something leave the solar system.

Very interesting stuff, though!

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Freethinker: Dark is the ABSENCE of light. It is NOT the opposite of light. It is strictly a relative relationship. What would be considered DARK in one relationship would be LIGHT in another. A cloudless full moon night would be dark compared to the day, but light compared to bottom of the ocean.

Seems you've contradicted yourself. If dark is the ABSENCE of light, as you so strongly emphasize, then if there is any light, then light isn't absent and it isn't dark. Therefore, what you go on to call a dark night is not a dark night since there IS light...moonlight.

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Tele, why, you seem to be in a singularly good mood today.

I think FT's point was to avoid confusion between light and dark as used when talking about what we see, and "light" and dark matter as something that is acompletely different concept.

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Freethinker: Dark is the ABSENCE of light. It is NOT the opposite of light. It is strictly a relative relationship. What would be considered DARK in one relationship would be LIGHT in another. A cloudless full moon night would be dark compared to the day, but light compared to bottom of the ocean.

Seems you've contradicted yourself. If dark is the ABSENCE of light, as you so strongly emphasize, then if there is any light, then light isn't absent and it isn't dark. Therefore, what you go on to call a dark night is not a dark night since there IS light...moonlight.

1) contrary to your claim, there is NOT always moonlight at night. (You might need to Google this if you are not yet aware of it. Try "phases of the moon", moonrise or moonset for example.) Thus the phrase DARK night.

2) try reading more than one sentence in a post. You will find I very specifically established "dark" to be "strictly a relative relationship" in the 3rd sentence. Again you may need to use Google or WWWebster if you are not familiar with the word "relative".

Thank you for being so singularly interested in my accuracy. I hope it gives you plenty of opportunity to do additional research. But please do it in front so I do not have to correct you and direct your activities later.