Science questions not worth a thread I: I'm a moron!

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I don't know what the theoretical maximum is. I do know the Tsar Bomba, while tested at 50mt, was actually designed to scale all the way to 100mt.

As for minimum designs, I have read that there a few non-Pu/U fissile isotopes that give frighteningly small (theoretical) critical masses on the order of single-digit kilograms. Most are very hard to obtain in quantity and the rest weren't that necessary considering all of the Pu/U infrastructure that was put in place.

Fuel/air bombs are much easier to produce and can be scaled down with no loss of reliability...and big ones can provide more than sufficient bang for any practical purpose. Other than the scary thought of nuclear weapons they are really pretty much obsolete I think.
 
Fuel/air bombs are much easier to produce and can be scaled down with no loss of reliability...and big ones can provide more than sufficient bang for any practical purpose. Other than the scary thought of nuclear weapons they are really pretty much obsolete I think.

I am not quite sure what you are saying. Is it that the total war against the whole population of a country is not a practical purpose, or that in a total war against the whole population of a country a nation with fuel/air bombs would be better off than a nation with ICBMs?
 
I am not quite sure what you are saying. Is it that the total war against the whole population of a country is not a practical purpose, or that in a total war against the whole population of a country a nation with fuel/air bombs would be better off than a nation with ICBMs?

Hmmmm...fuel/air bombs can be delivered by ICBMs. For all out annihilation nuclear may still be the best way to go, particularly if you already have them. But if I were starting from scratch with a non-nuclear capable country I probably wouldn't bother with nuclear weapons at all. You can get plenty of bang, easier.

At the other end of the scale, the same tech that you need to make the really big scorcher of a fuel air bomb can scale down really easily to make equally efficient bombs of pretty much any size you need. So instead of a really expensive nuclear weapons program making end of the world bombs plus a whole other program to make your just another day blowin' stuff up bombs, you get both from one less expensive program.
 
If you are a country that feels the need to be able to completely obliterate another country or at least a handful of cities, hyperbaric fuel-air bombs aren't going to cut it.

Because there are still countries that feel this need, there are still nukes.

Having said that and with no real thought investment in the subject, yeah, for smaller purposes than city-busting a hyperbaric will do the trick.
 
Do all animals with eyes descend from one single species that had eyes? When did it live and what do we know about it? (Perhaps better formulation: what is the latest common ancestor of animals with eyes?)
 
If you are a country that feels the need to be able to completely obliterate another country or at least a handful of cities, hyperbaric fuel-air bombs aren't going to cut it.

Because there are still countries that feel this need, there are still nukes.
I don't think that's why there are still nuclear weapons or countries actively developing them. Nukes are the ultimate deterrent. North Korea isn't developing nukes in order to attack someone - their program is a bargaining chip and an insurance policy against invasion. Same thing with Iran. GWB stupidly showed everyone what happens if you're on America's bad side and you don't have nukes when he invaded Iraq.

Same thing with Pakistan and India. Once India tested, Pakistan realized it needed to successfully test in order to keep India from getting to uppity. These days nuclear weapons don't serve offensive roles, thankfully.

Do all animals with eyes descend from one single species that had eyes? When did it live and what do we know about it? (Perhaps better formulation: what is the latest common ancestor of animals with eyes?)
From memory, eyes have evolved something like 5 or 6 times completely independently. The cephalopod eye is totally independent of the mammalian eye, which are both totally independent of the compound insect eye, for examples. So in order to find the LCA of sighted animals, you'd have to choose which clade you want to look at.
 
All that factors into 'a country that feels the need to...'

I'm not saying anyone intends to use them offensively but the job of nuclear weapon is to level cities and wide swathes of land/people/armies. So regardless of whatever causes a country to want this capability is beside the point I was making - I was simply stating what nuclear weapons do and how fuel-air bombs don't provide the same capability. Hence they are for different uses.
 
Any new breakthroughs in the Time Travel concept/field?
Besides the brilliant contraption from the "Napoleon Dynamite" movie.
 
Any new breakthroughs in the Time Travel concept/field?
Besides the brilliant contraption from the "Napoleon Dynamite" movie.

None that I know of. Time is still too poorly understood to tell whether traveling backward in time is even possible (forward is obviously possible). Currently, it seems rather unlikely that it is.
 
From memory, eyes have evolved something like 5 or 6 times completely independently. The cephalopod eye is totally independent of the mammalian eye, which are both totally independent of the compound insect eye, for examples. So in order to find the LCA of sighted animals, you'd have to choose which clade you want to look at.

This begs the question of how this happened. Once is near impossible considering eyes are not the only thing need to make sight possible, because you need to a supply of blood to both keep it cool and for sources a repair mechanisms so the eye doesn't get damaged from the light it takes in. Also there needs to be facial muscles that control the movement of the eye. There needs to proper wiring so that the signal can sent and lastly there needs to be the brain that is capable of interpreting the signals from the eye. Eyesight is a vastly complex thing.
 
This begs the question of how this happened. Once is near impossible considering eyes are not the only thing need to make sight possible, because you need to a supply of blood to both keep it cool and for sources a repair mechanisms so the eye doesn't get damaged from the light it takes in. Also there needs to be facial muscles that control the movement of the eye. There needs to proper wiring so that the signal can sent and lastly there needs to be the brain that is capable of interpreting the signals from the eye. Eyesight is a vastly complex thing.

To be honest, you've really answered the question yourself there - think how many times a sightless organism has been born in the couple of hundred million years, and how small a proportion of that number 'five or six' actually is. When dealing in unimaginably large numbers, you can expect the incredibly unlikely to happen on occasion.
 
This begs the question of how this happened. Once is near impossible considering eyes are not the only thing need to make sight possible, because you need to a supply of blood to both keep it cool and for sources a repair mechanisms so the eye doesn't get damaged from the light it takes in. Also there needs to be facial muscles that control the movement of the eye. There needs to proper wiring so that the signal can sent and lastly there needs to be the brain that is capable of interpreting the signals from the eye. Eyesight is a vastly complex thing.

Eyesight in humans is. But that did not appear at once. For every one of those requirements you list, you could find an organism that senses light without it.
 
This begs the question of how this happened. Once is near impossible considering eyes are not the only thing need to make sight possible, because you need to a supply of blood to both keep it cool and for sources a repair mechanisms so the eye doesn't get damaged from the light it takes in. Also there needs to be facial muscles that control the movement of the eye. There needs to proper wiring so that the signal can sent and lastly there needs to be the brain that is capable of interpreting the signals from the eye. Eyesight is a vastly complex thing.

Something like this:

http://en.wikipedia.org/wiki/Evolution_of_the_Eye

TL;DR The eye is probably the worst thing you can possibly throw irreducible complexity at. For every stage of the development of the eye it makes perfect sense how the development would represent an improvement over the previous iteration.

-Cells that can detect light simply (light/no light) aid in orienting an organism towards circadian rhythms.
-Further improvements help detect light intensity and direction
-Development of an "eye cup" helps refine direction
-Eventually deepening the cup becomes more of a hindrance and you get pinhole camera-esque design to help refine resolution
-Layer of cells added to help protect the photoreceptor cells.
-Specialization of eye components further helps improve vision
-Lens helps direct, focus, and discriminate against light.

There's even some inefficiencies in eyes that are really only explainable due to evolutionary arguments. For example we are only able to see along the "visible spectrum" because only blue and green visible light are capable of penetrating water.

You can even track the development:
Planarians still have that simple "eye spot" of a cup of photosensitive cells that can distinguish brightness and direction but not much else
The Nautilus has the "pinhole camera" type of eye that has no cornea or lens but is able to distinguish objects at very very low resolution
 
I remember an amazing thread in which carlosMM (IIRC) explained a whole bunch of stuff about how things evolved. It was genuinely beautiful and elegant, the way nature works.

Of course it all fell on deaf ears for some people.
 
Not that I imagine c_h is paying attention to this thread now that he's done his typical m.o. of drive-by posting something controversial and exfil-ing as the torrent of corrections rain down on the thread, but this passage from the wiki would be of particular interest:

The basic light-processing unit of eyes is the photoreceptor cell, a specialized cell containing two types of molecules in a membrane: the opsin, a light-sensitive protein, surrounding the chromophore, a pigment that distinguishes colors. Groups of such cells are termed "eyespots", and have evolved independently somewhere between 40 and 65 times. These eyespots permit animals to gain only a very basic sense of the direction and intensity of light, but not enough to discriminate an object from its surroundings.[19]

Developing an optical system that can discriminate the direction of light to within a few degrees is apparently much more difficult, and only six of the thirty-some phyla[note 2] possess such a system. However, these phyla account for 96% of living species.[19]
 
Cant say the numbers are right but generally yes. Early Earth rotated faster than it does today. The tidal interaction between the moon and Earth slows the rotation of the later and raises the orbit of the first. So you had a bigger moon in the sky as well as a shorter day. This process is still at work today btw.
 
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