Gilded

Well at least it's very, very fine but that doesn't really account for the color. Might be something used in the manufacturing process... perhaps carbon?

Whoops. Silly post deleted.

Well, anyways...

A. If light really does follow the surface, how can we ever tell it's curved? We'd be fooled into thinking the photons arrived from straight on.

I don't think "fooled" is the right word. At least I'd say sailing around the world in an apparently straight line is a worse case of being fooled.

B. How do we know the light that greets us is on its first voyage around the balloon? It could be on its third or fourth trip around (perhaps the universe expanded slower back during those few earlier voyages).

Actually, I think since certain wrapping CMB patterns haven't been observed it might point to an open universe rather than a closed one like the mentioned wrapping sphere. Then again, it might've just not had the time to do that. But whether the light has traveled "round" the universe should be visible from the wavelength shift.

C. Where on the balloon are the oldest galaxies/stars in relation to our cosmic neighborhood?

I'm not sure how to pinpoint them on the surface, but it's not like the universe has an exact set of coordinates. Anyway, they're far away from us.

D. The shortcut distance through the balloon is still immense. I'll assume the wormhole travel is supposed to be instantaneous. If so, why cut "through"? Wouldn't it be just as quick to have the wormhole cut across, following the universe's curvature, if wormhole travel is in fact instantaneous?

It isn't cutting through as much it is folding through. Imagine a stretch of paper representing a section of space. There's an ant at one end and a sugar cube at the other end. For the ant to get to the sugar cube in minimal time it should obviously move to it in a straight line. However, if this paper is folded into a ring so that the ends meet, the ant suddenly finds itself at the sugar cube without having to move at all.

(Of course to actually do that the sugar cube should be glued to the paper. )

The reason you can't do an experiment like that with even a gram of francium is that it's ridiculously radioactive. It's more radioactive than plutonium, neptunium, americium... The unstability tends to decrease as you go further into the transuranics, and even fermium isn't as radioactive as francium. As francium is so radioactive, it's hard to make a large amount of it as it quickly decays away. If you had an amount of francium visible with the naked eye your naked eye would probably boil off its socket. To put this shortly, francium is too radioactive to use in any chemistry demonstrations like that.

If those "idiots" placing alkali metals in bathtubs were the guys from Brainiac at least the cesium was faked by the way. But that doesn't mean a similar effect can't be achieved, they just did it wrong.

And no it wouldn't be very efficient compared to conventional bombs. And even if you had a ridiculous amount of let's say cesium you'd be better off using something else than water to oxidize it.

My next door neighbour is in his sixties and just took up the saxophone.

 

And my God is it annoying! Please please please, for the sake of your neighbours, leave it alone.

My former neighbor used to play the saxophone too. He played in a band and played really well, but nevertheless it was annoying as hell (hey, that rhymes).

They say idle hands are the devil's playthings and I suppose it's true if the owner of said hands decides to pick up a brass or woodwind instrument.

I saw some headcrabs and a guy with a crowbar. Is this bad?

Well by doing so Severian, you have violated the human rights of your daughter - who are you to say she was wrong to throw shit - If she want's to throw it then she should be allowed to do so - all aver your nice white shag pile carpet if it pleases her - it is her right as a human to do as she wishes!

Throwing shit has been one of the largest building blocks of our society. So many primates do it and have done it for so long that it's obviously an action of great importance, stemming from very primal instinct, and to forbid it is a horrible, horrible thing and a crime against humanity.

Everybody has seen two-way mirror - transparent from one side, reflective from the second ... isn't that Maxwell's demon for photons?

No. Two-way mirrors allow equal amounts of light through from both sides (is everyone missing this?). The illusion of it being transparent on one side and a mirror on the other side is because of the lighting in interrogation situations for example; one side is brightly lit and the observer side is dark.

Actually, I think a real two-way mirror would be in violation of some physical law... can't remember which though.

be extremely careful especially with the heavier metal oxides, some will practically Detonate and with little to no provocation!

milligram amounts can quite cheerfully remove a finger and as such should not be made at all.

Heh, I was just thinking how awesome it would be to make a gold or uranium thermite.

I don't know if this is any help or not: http://www.sciencemadness.org/talk/viewthread.php?tid=10249&page=1

 

There is a massive thread there about various thermite variations.

There has been some discussion about the more exotic thermite reactions on SFN as well, can't remember who has actually done them though. I've only done Al+Fe2O3.

But yeah, the stuff in that thread sounds about right. Essentially it's doable with dozens of different metal oxides.

Is there any proof (from measurements) for dark matter and its properties (like the angular momentum)?

 

I've always understood that "dark matter" exists only in our minds to fill in a very large gap in the models we have of the universe. also, all its properties were derived from the gaps in the model, because if it wouldn't have these kind of properties, the universe shouldn't behave as it does.

 

But I admit that this is not my field, and my post here should be seen as a question, not as an answer to a question.

There are a lot of widely accepted theories that haven't been proved yet, in science we just have to go on what we have at the moment. Dark matter being composed of particles like WIMPs is one theory, but no theory regarding dark matter has been proved yet. I just offered one example based on the particle version, but if the apparent dark matter is caused by something else than massive particles then I'm pretty sure it can't form black holes.

It is hard for dark matter to concentrate in a small area as it doesn't lose angular momentum. While dark matter could fall into an existing black hole and increase its mass, I'm not sure if it could form one completely by its own. It has been predicted (although I don't know if this is a mainstream prediction) that when dark matter particles concentrate in a very small spot they start to annihilate producing "normal" particles, preventing the formation of denser concentrations, preventing for example dark matter caused star collapse.

Anyway, you can find more about the angular momentum stuff here: http://curious.astro.cornell.edu/question.php?number=358

Would that be considered 3^rd base or 2^nd base?

I believe it's the 11-fold hyperbase. (The Zon Hyperbass is a cool instrument btw.)

Anyway, welcome people.

It is possible that space is "nothingness" simply from our inability to percieve it. Dont forget that far more of our universe is unknown than known. One of my favorite subjects in this vein is how does gravity or magnetism seemingly work at a distance with nothing but a "field" in between. What is the exact mechanism of that field? Is it instantaneous or does it have a speed like light?

The mechanism of those fields is rather well understood actually. There are mediating particles, and neither electromagnetic interaction nor gravity is instantaneous. Recently the "speed" of gravity was measured to be around c. And I'd rather not call space "nothingness" as it has various measurable characteristics. Nothingness is a rather abstract human concept.

I dont like the idea of neverending expansion. If the universe is ever expanding, what occupied whatever there was before our universe got there?

There doesn't need to be anything outside it. A rather good analogy is that the universe is a balloon, and that the perceived 3D space is reduced to two dimensions; the balloon's surface. Let's say there are dots on the balloon; as the balloon expands the dots get separated more and more, just like galaxies are doing according to our observations. The inside or outside of the balloon do not correspond to any physical location. In this model the universe wraps around itself.

Breathing bromine can result in an excruciatingly painful death as it corrodes the inner surface of your lungs and fills them up with many sorts of interesting fluids.

Indeed Mrsemmapeel, Americans must think we live in Victorian London!

Jolly good old chum, top notch! Tally ho! (????)

There's a big one growing in the backyard again... I wonder if I should put up surveillance in case some squirrels need their fix.

erm... I`m not in disagreement with you, I`m simply offering a possible Reason some associate that color with such materials, nothing more.

Yes I thought as much, I just elaborated on it since didn't think of that type of fluorescence as an especially good example as it is exhibited by so many materials when under UV light. But yeah I suppose some people might make that connection when they don't know that it's actually the UV that's causing it, rather than somehow highlighting an existing phenomenon that has something to do with the radioactivity of uranium.

Does that uber bump merit some type of award or something? But I would like to point out that my views on the subject have changed quite a bit from my transition from a student to a trained killer.

Virtual killing just doesn't feel the same anymore?

Statistically, I'm inclined to vote "Boy". Since YT obviously has some sort of super sperm (possibly armored with a lead plate mail) since he isn't completely infertile by now I'm ruling out the radioactive mutant possibility.

I'm gonna say some of the weaponry, sniper rifles and such from 'Mass Effect' because they were sweet. Also, whoever threw in the holodeck, you rock and bring me back one too! - Really if possible, I'd forgo anything else if I could get the Starship enterprise intact~ I'm not a trekkie by any means, but they had some sweet tech!

I found Mass Effect's weapons rather boring, especially due to the lack of variety inside a category. The point of getting better weapons in games is that they eventually look incredibly cool/absolutely ridiculous and have all sorts of awesome names like Antimatter Megablaster of Doom, instead of stuff like Striker VIII.

actually Uranium salts DO look the exact same green as shown on these cartoons etc... and will indeed glow under UV light.

here:

Fluorescence is a purely optical property of molecules and doesn't really have anything to do with nuclear activity though. It's just the material absorbing light in the higher part of the spectrum (UV) and emitting in the visible spectrum. If you point a UV light at a rod of plutonium it will not fluoresce like many non-radioactive minerals would. It's worth noting that the mechanism is the same though but in radioluminescence it's the alpha collisions exciting the electrons rather than ultraviolet photons. To summarize a bit, a green glow doesn't equal radioactivity and radioactivity doesn't equal a green glow.

It is not true that matter-antimatter reaction have to turn into photons only.

Yes, that's why I said "pretty much" which is of course a rather ambiguous expression as far as physics goes. I assumed the main focus was just energy production from antimatter, in which case there isn't that much of a need for higher energy collisions where other products than photons are favored.

Uranium is a metal and it looks like one. It's roughly the same colour as steel.

Indeed. And plutonium looks pretty much the same. And neither of them glow green. My chemistry teacher once said that if you're asked what a certain element looks like and you can't remember your best bet is "gray and metallic", which of course is a statistically sound guess.

When an alpha particle is emitted from the nucleus it's going way too fast to capture electrons, but it will quickly slow down enough after many collisions with surrounding atoms. This happens very fast; when alpha particles are emitted they have velocities of thousands of kilometers per second, and usually stop after a few centimeters in air. The +2 helium ion will then eagerly capture electrons from surrounding atoms, becoming a neutral He atom. All of this happens very fast in a fraction of a second, hopefully someone else can give a proper estimate.

To summarize, yes, alpha particles are helium-4 nuclei and will eventually become electrically neutral helium atoms when they slow down in an environment where electrons are available. The Earth's crust contains surprising amounts of helium for this very reason as abundant radioactive metals like thorium and uranium have many alpha decay events down their decay cycle.

Agree with your point. Having said that, the Simpsons is still a tv show.

 

It is one of the very few that care about getting science 'right' in the show

although, again, it can't be perfect.

Yes perhaps it wasn't the "fairest" example, I suppose it's one of those things the writers tend to do to get the point across as most radioactive material has a very boring appearance. All sorts of acids and poisonous liquids are often portrayed as being green as well even though many of them are colorless.