Re: New telescope technology

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:dtn7oo$9an$1@xxxxxxxxxxxxxxxxxxxxxxx
| Laury wrote:
|
| > Hmmm. 'Never say "never"'. Optical arrays became possible due to
the
| > vast increases in (not too expensive) processing power.
|
| That is only part of the tale. Optical arrays with phase compensation
| are only just marginally possible at a hard engineering level. Steel
| behaves like jelly at the tolerances needed.

That's true. My understanding was that the engineering was ready some
while back and the pioneers at Cambridge were waiting for the processing
capability.
|
| Even today replicating the original Michelson & Pease experiment of
the
| 1920's is well beyond the capabilities amateurs.

A bit too expensive! Otherwise I'd have done it for myself by now, just
to satisfy my scepticism about speed of light being constant. :) That
device was also the first to be used for astromomical optical
interferometry to determine the motion of Capella.
|
| > My first PC had
| > 30 Mb disk and about 0.3 megahertz cpu cycle time.
|
| By the time PCs had 30MB hard disks the clock speed was 4.77MHz or
| above, but with only tiny amounts of expensive memory fitted.

My mistake. In those days, I used 'multiply' time as a way of comparing
and had that in mind. The old girl still works, and I never did fill
that disk! It had an 8080 chip, and it 640Kb memory. To me then, that
wasn't tiny.

A far cry from my first micro, the 8008 with 2kb ROM, 2kb RAM & 2*256K
hard formatted 8" floppies which were truluy floppy.
|
| Today, 17 years
| > later, for about the same price as that was, I can buy one with 300
| > gigabyte & 1 gigahertz - 10,000 fold & 3000 fold respectively.
| >
| > OK, amateur telescope arrays will not happen this week, but who
knows
| > what will be achievable in 1000 years time.
|
| Even the most advanced designs and composite materials are still
subject
| to the laws of physics. To make interferometry work in a phased array

| you have to hold all relative path lengths of the optical components
| constant to fraction of a wavelength.
|
| It will never be easy or cheap to do this on Earth.

Perhaps I'm wrong, but I thought rather than trying to keep the
distances constant, the trick is to measure the distances and
incorporate that into the calculation. I haven't been able to find a
reference for that.

Anyway, given that the current number of usable professional instruments
is something like 20, it'll be a long time in the future before amateurs
will be able to use optical interferometry.
--
Laury



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