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Amazing stuff

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'yorz
1012609.  Sat Jul 20, 2013 12:22 pm Reply with quote

Nobuyuki Tsujii plays Rachmaninov's Concerto No.2 at the Proms.

Mr Tsujii is blind.

 
Jenny
1012614.  Sat Jul 20, 2013 12:36 pm Reply with quote

That's fantastic - thanks 'yorz. Listening to that as I type and will share on FB.

 
Troux
1012670.  Sat Jul 20, 2013 9:14 pm Reply with quote

Man learns to make the best of his tiny balls.



 
Efros
1013489.  Thu Jul 25, 2013 5:15 am Reply with quote

Amazing photos of an Orca hunting a dolphin. All the more amazing due to them being published on the daily wail.

 
'yorz
1014112.  Mon Jul 29, 2013 5:11 pm Reply with quote


I've seen this a several times over the past few years, but the shape was distinctly rectangular (portrait), and there were no clouds.
Anybody any ideas what could cause it (no, no alcohol or wacky baccy were involved).

 
Leith
1014118.  Mon Jul 29, 2013 5:37 pm Reply with quote

An ice halo of some sort, 'yorz? The picture above looks like a sundog.

More on ice halos and a variety of other atmospheric effects (and some nice pictures) here:
http://www.atoptics.co.uk/halo/common.htm

 
'yorz
1014119.  Mon Jul 29, 2013 6:08 pm Reply with quote

Although distance is of course impossible to gauge, it seemed a few miles away, and the shape was definitely rectangular portrait; a shimmering, iridescent, shape, I'd say about 4-5 inches long and 3 across. I would blink, as I figured it could be something on my lens, but it would remain, hanging in the air like a portal.
After a minute or two it suddenly wasn't there anymore.

 
Troux
1014137.  Tue Jul 30, 2013 12:56 am Reply with quote

Prince Rupert's Drop
Quote:
Prince Rupert's Drops (also known as Rupert's Balls or Dutch tears) are a glass curiosity created by dripping hot molten glass into cold water. The glass cools into a tadpole-shaped droplet with a long, thin tail. The water rapidly cools the molten glass on the outside of the drop, while the inner portion of the drop remains significantly hotter. When the glass on the inside eventually cools, it contracts inside the already-solid outer part. This contraction sets up very large compressive stresses on the exterior, while the core of the drop is in a state of tensile stress. It can be said to be a kind of tempered glass.

The very high residual stress within the drop gives rise to unusual qualities, such as the ability to withstand a blow from a hammer on the bulbous end without breaking, while the drop will disintegrate explosively if the tail end is even slightly damaged.




Related video:
http://www.youtube.com/watch?v=6V2eCFsDkK0

This video shows slo-mo of the drops exploding. This one is very interesting:
http://www.youtube.com/watch?v=Pdy2_vi0FfM

 
PDR
1014141.  Tue Jul 30, 2013 2:49 am Reply with quote

Yes, they're rather fun. They illustrate the principles used in prestressed (aka "rebar") ferro-concrete.

PDR

 
Troux
1014142.  Tue Jul 30, 2013 3:08 am Reply with quote

Efros wrote:
Amazing photos of an Orca hunting a dolphin. All the more amazing due to them being published on the daily wail.

I would like to raise speculation about those height estimates. I see closer to 25 feet than 15. Beautiful creatures, red teeth and all.

 
cornixt
1014193.  Tue Jul 30, 2013 10:11 am Reply with quote

'yorz wrote:
Although distance is of course impossible to gauge, it seemed a few miles away, and the shape was definitely rectangular portrait; a shimmering, iridescent, shape, I'd say about 4-5 inches long and 3 across. I would blink, as I figured it could be something on my lens, but it would remain, hanging in the air like a portal.
After a minute or two it suddenly wasn't there anymore.

The one in the picture looks very much like a ice halo judging by its loaction in relation to the sun. They are quite weird to look at, I saw one a few weeks ago as a huge rainbow circle around the sun, which broke up into sections as the winds blew. Yours was probably formed by a much smaller group of icy clouds so you only saw a single small section.

 
tetsabb
1014228.  Tue Jul 30, 2013 12:34 pm Reply with quote

'yorz -- I think it's a camera, and is already quite rectangular.
:-)

 
'yorz
1018887.  Sat Aug 31, 2013 4:04 am Reply with quote

 
NinOfEden
1018906.  Sat Aug 31, 2013 7:16 am Reply with quote

Troux wrote:
Prince Rupert's Drop
Quote:
Prince Rupert's Drops (also known as Rupert's Balls or Dutch tears) are a glass curiosity created by dripping hot molten glass into cold water. The glass cools into a tadpole-shaped droplet with a long, thin tail. The water rapidly cools the molten glass on the outside of the drop, while the inner portion of the drop remains significantly hotter. When the glass on the inside eventually cools, it contracts inside the already-solid outer part. This contraction sets up very large compressive stresses on the exterior, while the core of the drop is in a state of tensile stress. It can be said to be a kind of tempered glass.

The very high residual stress within the drop gives rise to unusual qualities, such as the ability to withstand a blow from a hammer on the bulbous end without breaking, while the drop will disintegrate explosively if the tail end is even slightly damaged.




Related video:
http://www.youtube.com/watch?v=6V2eCFsDkK0

This video shows slo-mo of the drops exploding. This one is very interesting:
http://www.youtube.com/watch?v=Pdy2_vi0FfM

What are they for?

 
swot
1018928.  Sat Aug 31, 2013 10:59 am Reply with quote

Nothing really, although Prince Rupert was very entertained by them. They're a handy illustration of the effects of stress on glass, and the slow motion video shows how waves travel through a solid.

 

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