Thanks Gym Duck anonymos
------- Original Message ------- On Thursday, August 25th, 2016 at 9:35 AM, jim bell <jdb10...@yahoo.com> wrote: > From: Georgi Guninski <gunin...@guninski.com> > On Thu, Aug 04, 2016 at 02:22:05AM +0000, jim bell wrote: > >>> http://www.dailymail.co.uk/sciencetech/article-3720772/China-launch-unbreakable-quantum-spy-satellite-say-one-day-lead-megascope-size-Earth-spot-license-plate-Jupiter-s-moons.html >>> [quote] >>> China to launch unbreakable quantum spy satellite - and it could one day >>> lead to a megascope the size of Earth that could 'spot a license plate on >>> Jupiter's moons' >>China (Austria is also involved) launched this on 16 August 2016: >> https://en.wikipedia.org/wiki/Quantum_Experiments_at_Space_Scale >>Also in many news. > > When I originally posted this, I briefly noted that I had a problem with this > news item. As I recall, one of the problems was that they referred to this > 'megascope', without explaining the connection. It was as if two high-tech > articles collided, and bounced off each other, leaving a bit of detritus on > the other. > What does this quantum link have to do with building a super telescope? The > article was less than even unclear: It was totally silent on that matter. > > Currently, the largest single-lens telescope mirrors are made in a rotating > furnace in Arizona, about 8.5 meters in diameter. the purpose of the > rotation is to make them very close to the idea curvature from the beginning, > rather than polishing them out of a flat blank of glass as was the previous > process. > Other telescopes are going to use multiple-mirrors to increase the > light-collecting > area. That's important, but another factor is that the larger effective > diameter > of a telescope mirror, the smaller angular difference that can be imaged. I > recall a data point: A 4.5 inch mirror has a resolution of about 1 second of > arc. > (defined, I think, as a line/space pair, not merely a line.) > A telescope based on an 8.5 meter lens will have, ideally, a resolution of > 0.0134 > arc seconds. Combine seven of them subtending a larger-diameter, and you'd > get perhaps 3 times the diameter, and one third the angular resolution: About > 0.00448 arc seconds. https://en.wikipedia.org/wiki/Giant_Magellan_Telescope > > Would it be possible to 'mount' three such 8.5 meter mirrors in an array > where they > are millions of kilometers away from each other, and somehow combine their > images > and to produce and preserve the resolution of the larger diameter? It > wouldn't multiply > light-gathering ability, but it would increase the angular resolution > immensely, perhaps by > a factor of 100 million to one billion. > I speculate that this is what is being alluded to in the article's reference > to a 'super telescope'. > It would not be sufficient to merely detect the images generated by each > mirror; somehow > it would be necessary to combine the light signals to include phase > information. Perhaps this > could be done by some sort of quantum process. > > Jim Bell