In article , says...

On 2/23/2012 8:08 PM, Richard wrote:
Like most of us (baby boomers) I grew up in a world that already had
nuclear weapons. We did "Duck and Cover" drills in school, and I
thought I had a fair notion about how these things worked.

But this photo (second one on this page) of the PU core of the
"Fat Man" implosion device - it's so small...fit's in your hand.




http://simplethinking.com/home/nuclear_weapons.htm

The majority of the energy release is nearly instantaneous, the mean
time from neutron release to fission can be of the order of 10
nanoseconds, and the chain reaction builds exponentially. The result is
that greater than 99% of the very considerable energy released in an
atomic explosion is generated in the last few (typically 4-5)
generations of fission -- less than a tenth of a microsecond.*

This tremendous energy release in a small space over fantastically short
periods of time creates some unusual phenomena -- physical conditions
that have no equal on earth, no matter how much TNT is stacked up.


A fascinating collection of high speed photos...

http://simplethinking.com/home/rapat...hotographs.htm

http://simplethinking.com/home/rapatronic_2.shtml

and the "rope tricks"...
http://simplethinking.com/home/rapatronic_3.shtml
Very impressive photos. I don't recall seeing them before.

Still the critical component is not described. It is the mechanism to
trigger the conventional explosive segments all at the identical time.
The key word being - identical. The failure of these devices in the last
North Korea test probably caused the dud. Until Iran is able manufacture
the devices and get them to work properly, all the uranium in the world
will not get them the bomb.

Except that with uranium you can use a simple gun. The imploding-sphere
design is necessary to work around the properties of plutonium, which
has to form a critical mass much more quickly than uranium or you get a
fizzle. Uranium just has to have two pieces slammed together really
hard.

By the way, this timing "magic" was achieved with 1940s electronics.
Shouldn't be any problem today.

If Pakistan can do it Iran can do it, don't pretend that it's beyond
them.