Whoever is at the cross-section between the comprehension of the biology behind this, and the direction of the visuals, is really gifted.

Something you may want to consider owning https://laughingsquid.com/star-wars-coaster-set-featuring-cross-sections-millennium-falcon/

My understanding is that even though nobody will admit to their actual capabilities, it's fairly widely believed that stealth doesn't work anymore.

While the radar cross-section might be the size of a large bird, which is always a major bullet point in their marketing material, no large bird is flying in a straight line at 5k+ feet and 400 kts and it's easily within the the capabilities of modern processing to sort out all the large bird sized objects and find the one that's behaving in a very un-birdlike way.

Of course, I suppose it's always better in a war to be seen as little as possible, but newer projects like the F-22 and more specifically the F-35 are probably handicapped by being held to meeting the "stealthy" design requirement.

If the people asking the question were American that would have affected the response.
The relationship America has with firearms, christianity and capitalism is what most europeans I know (a pretty good cross section) would highlight..
And topically what the hell is going on with their police force at the moment..

What about a superconducting magnet being used to suspend a top, both in a vacuum and not?

Similar to this - which is smooth shell/continuous cross section but sadly very short in duration.

I wonder if he would have gotten the same result if he'd spun a top with a smooth shell/continuous cross section?

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Good point... they need to patent the cross-sectional shape of the glue sticks, so that normal media won't fit.

And how is that an authoritative source? It's from a stupid blog...an obviously very biased blog.

none of which even touches my argument about diversity.

>> ^silvercord:

The average age (mean) of the speakers at the DNC was 58.66 while at the RNC it was 49.92.
From modicum of insanity:
Of the speakers in the DNC, there were 9 current governors and 5 former governors. 22 members of the House of Representatives, 2 candidates for the House, and 1 former House member spoke. 5 current senators and 2 former senators also spoke.
Of the current governors that spoke, the average age was 57.44. Of the current House members that spoke, the average age was 62.64. Of the current senators that spoke, the average age was 67.2.
Of the speakers at the RNC, there were 10 current governors and 5 former governors. 9 current members of the House of Representatives, 1 candidate for House, and 2 former House members spoke. 7 current senators, 4 former senators, and 1 candidate also spoke.
Of the current governors that spoke, the average age was 50.3. Of the current House members that spoke, the average age was 50.67. Of the current senators that spoke, the average age was 52.83.
I wouldn't count 'em out just yet when it looks like the DNC is the party that's getting a little long in the tooth.

>> ^VoodooV:
Comparing the two national conventions alone should be enough to convince anyone that the Republican party as we currently know it is in its last years.
RNC: by and large, mostly old white people
DNC: Actual cross-section of America and vastly more diverse.

"Of the speakers in the DNC ... 22 members of the House of Representatives" well they just blew the curve.

As for the RNC convention, I think what we saw was either a conscious effort to "go younger" and entice younger voters, or a symptom of the greater problem with modern conservatism: namely that serious, mature conservatives don't want anything to do with these lunatics.>> ^silvercord:

The average age (mean) of the speakers at the DNC was 58.66 while at the RNC it was 49.92.
From modicum of insanity:
Of the speakers in the DNC, there were 9 current governors and 5 former governors. 22 members of the House of Representatives, 2 candidates for the House, and 1 former House member spoke. 5 current senators and 2 former senators also spoke.
Of the current governors that spoke, the average age was 57.44. Of the current House members that spoke, the average age was 62.64. Of the current senators that spoke, the average age was 67.2.
Of the speakers at the RNC, there were 10 current governors and 5 former governors. 9 current members of the House of Representatives, 1 candidate for House, and 2 former House members spoke. 7 current senators, 4 former senators, and 1 candidate also spoke.
Of the current governors that spoke, the average age was 50.3. Of the current House members that spoke, the average age was 50.67. Of the current senators that spoke, the average age was 52.83.
I wouldn't count 'em out just yet when it looks like the DNC is the party that's getting a little long in the tooth.

>> ^VoodooV:
Comparing the two national conventions alone should be enough to convince anyone that the Republican party as we currently know it is in its last years.
RNC: by and large, mostly old white people
DNC: Actual cross-section of America and vastly more diverse.

The average age (mean) of the speakers at the DNC was 58.66 while at the RNC it was 49.92.

From modicum of insanity:

Of the speakers in the DNC, there were 9 current governors and 5 former governors. 22 members of the House of Representatives, 2 candidates for the House, and 1 former House member spoke. 5 current senators and 2 former senators also spoke.

Of the current governors that spoke, the average age was 57.44. Of the current House members that spoke, the average age was 62.64. Of the current senators that spoke, the average age was 67.2.

Of the speakers at the RNC, there were 10 current governors and 5 former governors. 9 current members of the House of Representatives, 1 candidate for House, and 2 former House members spoke. 7 current senators, 4 former senators, and 1 candidate also spoke.

Of the current governors that spoke, the average age was 50.3. Of the current House members that spoke, the average age was 50.67. Of the current senators that spoke, the average age was 52.83.

I wouldn't count 'em out just yet when it looks like the DNC is the party that's getting a little long in the tooth.


>> ^VoodooV:

Comparing the two national conventions alone should be enough to convince anyone that the Republican party as we currently know it is in its last years.
RNC: by and large, mostly old white people
DNC: Actual cross-section of America and vastly more diverse.

Comparing the two national conventions alone should be enough to convince anyone that the Republican party as we currently know it is in its last years.

RNC: by and large, mostly old white people

DNC: Actual cross-section of America and vastly more diverse.

To continue this lesson, it is important to note that most bomb technology doesn't use enriched uranium alone. The other key material compound is plutonium. For all intents and purposes, all plutonium is man made (with only traces of 244 found in nature, of which is completely unsuitable for weapons..Pu244). Plutonium is usually needed in a bomb because of its much lower critical mass. This lower mass makes bomb fabrication easier, but that creation of plutonium is by no means trivial.

You need huge facilities, dedicated to the sole purpose of uranium exposure. Like the video mentions, normal uranium is mostly U238, this junk gains value in the creation of plutonium. Weapons grade plutonium is a special isotope of plutonium, Pu239. This need is very specific, the different isotopes of Pu can have so very serious implications for bombs. Lets go over them as we as we go over how uranium is exposed to make this very special isotope

First, we start off with U238...the fuel stock. This isotope is bombarded with neutrons. These neutrons are occasionally absorbed by the uranium, turning it into U239. U239 is highly unstable, and quickly decays (in 23.45 minutes) to neptunium 239. This will in turn, decay into Pu239 (in about 2.3 days). Sounds easy, right? Not exactly, neutron absorption isn't something you can control with ease. What I mean is, there is little to stop our Neptunium or Plutonium from absorbing neutrons any more or less than the Uranium (in fact, their absorption cross sections are typically much larger...they are more hungry of neutrons than uranium in other words). When this undesired absorption happens, the neptunium and plutonium eventually becomes Pu240...and that is a big problem.

Plutonium Pu240 is HIGHLY undesirable in a bomb. Pu240 is a medium lived isotope of Plutonium, meaning it decays pretty quick, but it is HOW it decays that is the problem. Pu240 often decays by spontaneous fission. Having spontaneous fission in your fission bomb is just as undesirable as it sounds. Firstly, all even number isotopes are poor fission candidates, so for every even number isotope in your bomb, that lowers the bombs over all yield (because they prefer to fission themselves, and for very little return energy). This is further complicated by high densities of Pu240 causing your bomb to prematurely detonate, ya...bad news. The levels of Pu240 represent yet another challenge in the level of heat they generate from their rather quick decay, though, considering the previous 2 issues, this one is less problematic, though still troublesome. And lastly, there is nothing stopping our Pu240 from absorbing yet another neutron causing yet another isotope of plutonium to arises, namely Pu241.

Pu241, being an odd numbered isotope heavier than lead makes it a rather good subject to undergo fission. It doesn't have the same set of problems as Pu241, but it rapidly decays (14 years) into Americium 241, which is not fissile, and has a halflife of 432 years. These factors add large amounts of heat to the bomb, and reduce overall yield, as well as detract from critical mass.

The solution for this is a very low tech, time consuming, laborious process with produces tons of waste and very little plutonium. One has to expose small blocks of uranium to neutrons under a very brief window. The brief window decreases the chances of undesired neutron absorption and negates much (but not all!) of the heavier forms of plutonium being created. After exposure, they are left to decay, then after a few months, are chemically processed to remove any plutonium and other undesirables (this is also very very hard, and I won't even go into how this is done), then re-exposed. This yields gram(s) at a time. To make a weapons, you need 10 killos, at least...for one bomb...if everything went great. This means you need HUGE facilities, HUGE staff, and HUGE uranium resources. Your facility would be obvious and serve no other purpose, use tons of energy, and pile up radioactive waste of the kind no one wants, heavier than uranium wastes...the worse of the worst. No such facility could exist alongside some traditional uranium facility and not be noticed, period, end of story, done.

We haven't even covered bomb making problems, of which killed some of our top minds in our own bomb program. A set of incidents revolving around a specific bomb type, after taking 2 lives, was dubbed the Demon core. These are the reasons over half the budget of the DOD gets soaked up in nuclear weapons, and we haven't even covered some of the more important aspects (like delivery systems, one simply doesn't walk into Mordor). Nuclear weapons are hugely expensive, hugely conspicuous, require massive facilities and require a level of sophistication that is completely absent from the training of reactor nuclear scientists.

Reactor research and materials are orders of magnitude different from weapons grade materials and research. No bomb in history has EVER been made from reactor grade plutonium because the levels of Pu240 and Pu241 (and we haven't even covered Pu238!) are blisteringly high, way to high for weapons. Isotopic separation for Pu would be even more costly than uranium because of their mass similarities (compared to U235 and U238) and need a different set of enrichment facilities specially tailored to plutonium enrichment, of which all the people who knew something about that are Russian and American, and most likely dead or work classified to the highest degree.

The problem of nuclear weapons via reactor development is all a game to ratchet up the fear machine to get a particular end. It isn't a technical problem, it is a political problem. In the end, though, emerging technology could make enrichment easier anyway, so many of the issues I mentioned might eventually fall to the wayside (not within the next 10 years I imagine; for interested parties, google laser enrichment...coming to a world near you, but not exactly tomorrow, it's awesome stuff though). Eventually, the US is going to have to get used to the idea of more and more nations owning the bomb...but that issue is completely unrelated to reactor design and research. Reactors and nuclear weapons share about as much in common as cars and space shuttles...trying to link them as a dual proliferation argument is a political game and doesn't map on to them technologically.



I should note that I am not yet a nuclear engineer, but I did stay at a holiday inn express.

FYI - The video shows that having a constant diameter (cross-section) is not enough to show the shape is round. This was discovered to be a problem in getting segments of the Space Shuttle solid rocket boosters to fit together. (The SRB segments would flex out of shape when they were transported across country lying sideways on railcars.) They had to be forced back to a round shape to fit together, with the O-rings in the gaps. As described in Richard Feynman's book, "What Do You Care What Other People Think?", NASA would measure diameters at different points. But Feynman knew about the funny shapes in this video, and knew that diameter measurements did not prove roundness. The technicians on site always had to keep inspecting the segments as they came together to get them to fit together.

It's a shape that, because it "wobbles" around it's centre axis, rather than rotating around its centre axis like a wheel, it can present a consistent cross sectional width between two parallel planes. In reality, there are three points it rotates around at any particular time, depending on what point it's at.

Think of it as 3 pie shapes. It rotates on a point at the book, and when it finishes it's arc on the table, THAT becomes the new pivot, and the book travels on the arc, then the table, then the book... etc.

What's neat is you can do this with any odd-sided polygon. It won't work on even numbers.

Yeah, I'm deleting that last part as there's too many conditions for that to be simple.