Dark matter compass

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Offline science_guy

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Dark matter compass
« on: 24/01/2007 16:13:16 »
I have recently learned that dark matter will, if only rarely, come in contact with normal matter, although it produces no noticible effects because of how small it is.

so if you had a vacuum cylander standing upright on the equator with a flap attached to one edge of a central axis, and the axis has no resistance to it turning, would the dark matter be able to move the flap so that it will be pointing west, since earth turning eastward might be affected by dark matter?

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Offline realmswalker

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Dark matter compass
« Reply #1 on: 26/01/2007 00:51:08 »
hmm well i think that the problem with this idea would be how dark matter interacts with normal matter...
Can dark matter exert a force on normal matter?
Is there sufficient dark matter on or around earth to do this?


Offline Soul Surfer

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Dark matter compass
« Reply #2 on: 26/01/2007 09:15:51 »
Dark matter interacts with ordinary matter through the force of gravity so we are already experiencing any force that it may generate.

If you are inside a large gravitating lump with no noticable edges  (it seems that dark matter is only observable in galaxy sized lumps) the only gravitational force you will experience is that of any differences in density of dark matter which are likely to prove very small.  They would also have shown up as random errors in many physical measurements to it is reasonably certain that any effects are too small to be observed.

You also have to remember that your velocity with respect to the whole observable universe at any moment is a very complex thing because standing on the equator you are going round the earth at around a thousand miles an hour.  With the Earth round the sun at 18 miles a second.  With the sun round the galaxy at 200 miles a second and with the galaxy towards the great attractor at about 500 miles a second.  ant thats not taking onto amount the effects caused by the moon and the other planets which are all significant in terms of miles an hour
« Last Edit: 26/01/2007 09:18:25 by Soul Surfer »
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