On Wed, 2008-05-21 at 13:43 -0500, Robert Derman wrote: > Daniel Carrera wrote: > > Ian Lynch wrote: > >>> this is agreed to be unsatisfactory, > >> > >> Yes it would be difficult to see how the measurement might be checked > >> without losing the odd atom or two :-) > > > > Wikpedia says that the lump of metal gains mass because it absorbs > > atmospheric contamination. So they have this complicated technique to > > clean it, and the technique removes about 5-60 micrograms of > > contaminants. I imagine that you have to worry about not removing too > > much stuff every time you clean it. > > > > They actually have several replicas around the world, for mutual > > calibration. But it turns out that these masses have been diverging > > from each other. The base prototype (the one that truly defines the > > Kg) has lost about 50 micrograms in its life compared to the replicas. > > Nobody knows why. So they also don't know whether the main prototype > > has lost mass or whether the replicas have gained mass (maybe they > > replicas don't get cleaned as well?). And of course, it's possible > > that they are all diverging one way or the other, and we wouldn't know. > > > > There is an additional 30 microgram monthly variation in the > > proptotypes which is not explained either. > > > > Daniel. > I have an odd theory, nothing to back it up really, but here goes -- > what if "dark matter" tends to drift in and out of normal matter, > doesn't interact, isn't detectable by any means except by its actual > mass. I have not heard of any other theories that make any more sense > than this to explain this phenomenon.
Bit like neutrinos. ISTR that neutrinos have a mean free path of 144 light years in iron so they are pretty difficult to detect but they do have a notional mass. I think the calcs showed that neutrinos couldn't be responsible for dark matter. Probably something in wikipedia about it if I could be bothered to look it up :-) Ian -- New QCA Accredited IT Qualifications www.theINGOTs.org You have received this email from the following company: The Learning Machine Limited, Reg Office, 36 Ashby Road, Tamworth, Staffordshire, B79 8AQ. Reg No: 05560797, Registered in England and Wales. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
