User talk:Headbomb/Archives/2015/July
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"Isotropy implies Homogenity"
Hi Headbomb, we've been fighting over this issue - you claim it is true, I claim it's false. We both firmly believe in the Cosmological Principle, the Universe is both isotropic and homogeneous. But it is still a matter of faith, we can never prove it. The statement "Isotropy implies Homogenity" is based on the existence of TWO separate points that are BOTH isotropic - certainly quite far from each other. At my backyard the universe looks isotropic, and and I don't think your backyard is very different. But the distance between these two places is far to short. Let me quote the report you referred to in the article :
" It is therefore a reasonable supposition that, if the universe appears isotropic about our position, it would also appear isotropic to observers in other galaxies; the term "isotropic" is therefore often employed in cosmology as a shorthand for "isotropic about all locations"."
This suppostition that the universe seems isotropic to observers in other galaxies is quite reasonable - BUT! Darned!! it is based on our firm belief in homogenity - that no place is very much different to another place. We can't really PROVE that the sky is isotropic elsewhere, thus the word "implies" is inappropriate. So the correct statement should rather be "If the universe is homogeneous, then isotropy implies homogenity" ;-). And, by the way, what has homogenity to do with "The Horizon Problem" anyway? Hilmer B (talk) 22:14, 5 July 2015 (UTC)
- You got the reference. I suggest you read it. Isotropy + Copernican principle = Homogeneity. "Established" or not, this is the mainstream position. Headbomb {talk / contribs / physics / books} 02:49, 6 July 2015 (UTC)
- OK, so we can both agree on "Isotropy + Copernican principle = Homogeneity". And that the validity of the statement depends on the validity of the Copernican principle? That "Isotropy + no Copernican principle ≠ Homogeneity"? That IF the Copernican principle was false (which I definitely don't think it is!), then Isotropy would not imply Homogenity? And can we also agree on that the Copernican principle is the mother of Homogenity? So that you have to add homogenity to isotropy to get homogenity?!? And finally - please remember one thing - the Wikipedia articles are written for the general public , not for professionals in the cosmology industy. POOH - now I'll say no more! Hilmer B (talk) 09:10, 6 July 2015 (UTC)
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Nowrap
I added the {{nowrap}} because the {{su}} template and (sometimes) the slash symbol are incorrectly identified as break points by browsers, so you can see things like K
- or J/
Ψ meson. It's a bigger problem in image captions than body text, but better to be safe than sorry. Smurrayinchester 14:07, 16 July 2015 (UTC)
About "(full name: Ioffe-Penning trap[citation needed][dubious – discuss])"
Dear Headbomb,
I wanted to reply to your dubious/citation needed. I was referring under the line, “to store antimatter like antiprotons.” A lot of the article has been written in a way that refers to the Ioffe Penning trap used by ATRAP and antiprotons specifically. However, I did fact check myself, and CERN now uses both the Ioffe-Penning traps and Penning-Malmberg traps to trap antimatter in general. My point when adding that its full name was Ioffe-Penning was more to point a Penning Trap is never use alone to trap atoms especially Antimatter. I hope you could maybe rephrase the “(full name: Penning Ioffe trap)”, and rephrase by adding this line to the end of the first paragraph “A Penning Trap alone is not used to trap antimatter, but it is used in combination with other atomic traps--the most famous being Ioffe-Penning trap (by CERN’s ATRAP) and Penning-Malmberg trap (by CERN’s ALPHA)." As for citations, I will show my sources so you can use any source from 1 and 2 or even just both of 3 below as citable sources.162.242.9.13 (talk) 00:19, 19 July 2015 (UTC)
1) Ioffe-Penning Trap was one of the first traps used for Anti-Protons and later Anti-Hydrogen. As far as I can tell, CERN ATRAP is still using an Ioffe-Penning Trap. Sources:
- http://gabrielse.physics.harvard.edu/gabrielse/papers/2007/AntiprotonConfinementInAPenning-IoffeTrap.pdf
- http://gabrielse.physics.harvard.edu/gabrielse/papers/2008/AtrapHbarProducedInPenningIoffe.pdf
- http://web2.uwindsor.ca/psas/Abstracts/Hessels.pdf
- http://gabrielse.physics.harvard.edu/gabrielse/overviews/Antihydrogen/Antihydrogen.html
- http://press.web.cern.ch/press-releases/2013/03/atrap-experiment-makes-worlds-most-precise-measurement-antiproton-magnetic
2) ALPHA uses a Penning trap variation called a Penning-Malmberg trap. 162.242.9.13 (talk) 00:19, 19 July 2015 (UTC)
3) Building on the precision errors with ATHENA (Penning-Malmberg) and ATRAP (Ioffe-Penning), the Alpha website notes that “Ioffe-trap variant” was used in the magnetic coils to help load the positrons and anti-protons into the Penning-Malmberg trap. (Also, if you read the news surround the 2011 paper, they used some of the anti-protons trapped from the ATRAP experiments.)
My point when adding that “full name: Ioffe-Penning” was more to point a Penning Trap is never used alone to trap atoms especially Antimatter. Part of the reason with this is the precision needed at the scale at one is trapping the antimatter that is coming off the decelerator, which I hope you gotten from the articles. Another reason in general that combinations of traps are used is because with neutral atoms, the Penning-Trap, like other traps cannot trap neutral atoms alone. In fact, in laser cooling studies, neutral atoms have to rely on the Zeeman-effect to trap atoms. https://en.wikipedia.org/wiki/Zeeman_effect#Laser_cooling 162.242.9.13 (talk) 00:19, 19 July 2015 (UTC)