thedarkshade

200 years back from now, saying that one day two people 20000 km away from each other will be able to talk for the issues of the same hour, you would be called crazy! 200 years back from now if you said to anyone that all the people of the world will see the same thing on something called TV, you would be called crazy! And perhaps 200 later form now mankind will laugh with thoughts like this one that we will never find the Theory of Everything. Science shall make it!

There are lots more reactions, but they all start with the U-236 compound nucleus you have after U-235 absorbs a neutron. Technically they are not decays, since they are induced rather than being spontaneous.

 

The fission yield curve shows what the range of products are by mass; you'll get one large and one small one, plus a few neutrons.

 

The slow neutrons are produced by slowing doen the fast neutrons emitted in fission. They aren't really "injected" into the core; they are already there. There isn't a moderator present in a bomb. Fast neutrons can initiate fission, but they generally have a smaller cross-section for doing so. You just have to engineer things accordingly (e.g. the critical mass will be different if you are relying on fast fissions)

Yeah, they all do start with U-235. And this link provides quiet good explanation about these things.

http://youtube.com/watch?v=fnY_Ug0DabM

The Hiroshima Atomic Bomb was build based on these principles. U-235 has the ability to absorb neutron, so you need a neutron to break it into two "smaller pieces". There are some methods of getting neutron, like the Be one. All you got to do is act with alfa rays to a berillium and automatically a neutron shoots out. And when that neutron hits the nucleus of the U-235, it breaks the balance proton-neutron and the nucles breaks into two (Ba-142 and Kr-91, called F-fragments) and releases three neutrons. The probability that the neutron released from Be to hit the nucleus U-235 is quit astronomical, and critical mass in necessary for this to happen. Critical mass is usually spheric so the neutron cannot leak out. And then three other neutron released form U-235 hit the other nucleus' and so it always keeps on doubling. The key thing about uranium bomb is neutron. Super-fast moving neutrons double the other U-235 while the explosion is still in progress, releasing so the largest energy existing (nuclear energy). And it was the energy (heat) that killed all those people in Hiroshima.

Another "bad" effect of the nuclear explosion is also radiation. Except the released energy there is also released radiation, which consequences show up gradually. Still today, the level of the radiation on Hiroshima is 10 times higher than normal.

I agree.

Among working cosmologists, I have never heard or read

the big bang described as an explosion.

that image just would not make sense

 

an explosion requires some surrounding space for stuff to explode OUT INTO.

 

in standard professional cosmologist view, there is no surrounding space.

so there is nothing that resembles an explosion

 

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the big bang event is modeled in various ways

in a lot of recent research papers it is modeled as a bounce

where space is collapsing and reaches a critical density (where gravity repells due to quantum corrections) and then starts expanding.

 

I guess there are a hundred or so research papers that model it along those lines and study the consequences. some computer modeling. some analytic.

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ScepticLance mentioned another approach----"brane collision"

many papers written about that scenario too.

I haven't read much about that scheme, but it is certainly out there!

 

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and in a lot of older work they just leave it as a GAP where the model doesnt extend and they don't yet have an idea what was happening. the gap or glitch in the model (where it stopped working) was called the "singularity"

 

I'd say the trend now is away from that though. the trend is to fix the gap, resolve the "singularity"---in other words use an improved model to get rid of it.

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another scenario that gets rid of the singularity is called "eternal inflation" or "chaotic inflation". it impresses me as pretty speculative and unable to predict anything. too hand-wavy. but that is just my opinion.

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among professional cosmologists---at the big international conferences like GRG (General Relativity and Gravitation, held every three years, this year in Sydney)----what is getting the most attention is the LQG bounce picture.

 

Largely, I think, because you can calculate stuff like big bang nucleosynthesis, abundance of elements, structure formation---or anyway they are beginning to do that---and the quantized model looks very much like the standard bigbang/expanding universe model that cosmologists are used to dealing with.

 

The only main difference is that the model doesn't break down as you go back in time.

there is no place where you have to give up in defeat and say "at this point everything was created out of nothing"

 

that makes the professional astrophysicists happy, so if you look at the line-up of invited speakers at the next international conference having to do with general relativity and cosmology it will probably have a bunch of LQG speakers.

 

my impression anyway. the next one is in India, December I think. we could check just to make sure my impression is right.

Yeah. Here are some links---I make a post about the conference. Programme shows how things are going.

http://www.scienceforums.net/forum/showthread.php?t=29324

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exciting times in cosmology, these days.

a lot of rapid change

It's kinda strange why all those graphs and maps related to Big Bang progress only on one side! According to what I've read and seen about Big Bang, the very initial ancient state before or right at the Big Bang was infinite density and zero volume. This latter one has been having some hiccups quiet frequently, but what I'm trying to say is that at the beginning was only a point (infinitely dense and zero volume). And a point is circular. So any progress (like explosion or better to say expansion) done to this point should have gone steady to all directions. So why all maps and graphs (even Wiki's) progress in one direction? what about the other part? Excluded from universe???

The creation of everything from nothing all at once....

So you agree that universe was created from nothing (volume zero), because many don't. So creationism or eternal universe? Which you think is the one?

Well... Try not to lose too much sleep. Think about the numbers involved. Suppose you have, say 10^23 electrons. This is a pretty common number in chemistry---this is like a thimble full of whater. So we have these 10^23 electrons, and we want to do a calculation of something. In order to do the calculation fully, using quantum mechanics, we would have to know instantaneously the state of the 10^23 electrons, spin up or spin down. This means 10^23 bits or 10^14 gigabytes of data all at once. This is roughly five orders of magnitude (10,000 times) more information that the biggest hard drives that I know about. And this is just to know what state the electrons are in---we haven't even done a calculation yet.

 

So it's not that we can't concievably do it, it's that we can't fesably do it.

 

Instead, we use statistical treatment---this is the field of statistical mechanics, which is very useful for people calculating things with lots of electrons.

 

 

 

I agree with you. I think string theory is the answer:)

I completely agree.

I personally think that the point of each task you get (physics in this case) or any task you set yourself is to get the result, accurate and fast result! Classical methods have no problems getting this, so why replace? on the other hand the "usual numbers" used in QM are astronomical. This would be just like saying "will mankind ever chose the hard way instead of easy way"!

And about QM-Relativity!

QM, as you all said, fits with Special Relativity as they both got to deal with high speed and extreme conditions (at least not experienced in out daily life). But the problem (Modern Physic's main problem probably) is that QM does not fit with General Relativity! And I've often heard that one of these Relativities has got to be wrong (thought I don't think so)! Or something inside QM or General Relativity has got to be wrong! They just got to fit, as they're both right on their own "paths". I'm saying this because these paths are part of the same world, same universe! QM and General Relativity both deal with the same universe (differing in scale), so how come two exact theories, about the same thing don't fit? Why do they differ?

Do you mean to upload and store information in the same way is can be stored on something like a computer hard drive?

Store informations into earth just like into a hard-disk? Who's the storer then? Mankind? How?

There is no way to make an infinitely small piece of matter. You could still make it smaller.

There is this limit for smashing everything into something smaller! For example you can smash a magnet till feromagnetic particles, but not smaller. And to matter as general, string (if it exists) is the limit!

I was thinking of the universe as spheric too. In all those graphs of the Big Bang you always see it progressing in one direction, when it should be in all directions. And that the whole thing is rotating putting us and all the other parts of the universe in different places in the universe, making us impossible to find out where we actually in the universe and find out where are the edges of the universe!

As far as I can understand it, Dark Matter is just like a gum that acts between all substances in the universe, and it makes it impossible for them to get away form each other (stop galaxies from running away form each other). I was thinking if I could look at it this way and I got a thought! If dark energy starts decreasing that means that dark matter will start increasing pulling everything closer to everything, until it gets to a state were density will be infinite and volume 0, that means the state before Big Bang. Possible???!!!

Massless and frictionless are two adjectives which are unknown for realistic situations so this one is completely idealistic, so we'll treat it that way. As you say that this plane is incline and frictionless, any forced acting on it (vertically as you said) would just slip (because of frictionless situation) and it would also slip from the rail too (as it is also frictionless), so no force (acting vertically) would be able to make this plane move. This slip is caused from the frictionless situation and also because of the angle which cannot be zero. If the force acts from left, than it would make the plane move infinitely with a constant velocity.

At least I picture it that way!

If not an explosion, than what?

They are so many fact that deny the evolution, evolution itself denies evolution, and we still blindly believe on it. How irrational mankind can be! First of all I just want to clarify an issue! MUTATIONS! I've been reading all those replies and I find it difficult to believe how can "scientists" think and say that the mutations have contributed to evolution! This is insane! To deny this thing all you need is very very basic knowledge about genetics. Mutations are changes that happen during replication (DNA synthesis), transcription (RNA synthesis) and translation (protein synthesis). But one thing we should understand is that MUTATIONS ARE ALWAYS NEGATIVE!! There still hasn't been A SINGLE case when mutations have had positive effects in that organism when they happened! From the foundation of the genetics, for more than 50 years scientists have been trying to cause, experiment or observe a positive mutation but they always ended up failing. This is because there are no POSITIVE MUTATIONS. Just think of some mutations like Down's Syndrome, Condiodistrophy, Albinism etc, they're positive right???!!!

One scientist used a really good expression to illustrate this case "The hasn't been a single case when mutations have contributed positively in the development of the organism. This is like an earthquake to have positive effects to a city!" And he's actually right! So how could organisms evolve in a higher scale of development by mutations when the word "positive" is absolutely contrary to mutations!

Another impossible maze for evolutionists! How did mammals appear and what happened to reptiles? When it comes to this evolutionists usually have only one thing to lean on, and that is Archeopterics! They say that this creature was the "bridge" between reptiles and mammals! And they failed again here, because Archeopterics was warm-blooded, which means a mammal. And yet evolution cannot explain the pass reptile-mammal! A very interesting quotation about this issue is: "The passing phase between reptiles and mammals is still a mystery! This is just like a play when all the key roles are taken by reptiles and the curtains suddenly go down. And when the play starts again the key roles now are played by mammals!"

Yet another impossible maze for evolution! LAND-WATER

How do evolutionist explain this? They do it but still using a failed example. And the example is coelacanth. Coelacanth is oldest specie of fish living. When it was first discovered, this was a great breakthrough for evolution because coelacanth is thought to have a weak walking mechanism. But after the capture of more coelacanths, the conclusions say that it is a fish that lives in deep water and never goes higher than 180m. What is ridiculous about this land-water pass is the original example used by Darwin! And guess what he said:"I see no barrier for a bear to be converted into a whale by jumping into water" For the love of God how can a thing like this happen! Explain it evolutionists! Then another blockade for evolution is Cambrian Explosion!

To not make this more boring I'll just use a very simple, convincing example! Evolutionists say that mankind has evolved from apes, and that the Homo-Sapiens first appeared about 60000 years ago. Then how do the evolutionists explain the discovery of a 1.6 million year old man footstep? Then all those scandals with falsified fossils and skulls (which I would not like to mention).

And if mankind evolved from apes, then how come that not a single man has evolved from an ape for all this time that mankind has been present?

CONCLUSION : E V O L U T I O N I S F A K E

I completely agree with you. Evolution means reaching a higher scale of development, more complicated, more advanced. And according to evolution these advances happen by mutations (well according to neo-darwinists), but mutations only have negative effects, never never never positive. Then how come NEGATIVE mean ADVANCE?

And also that the probability for creating any new biological structure or any new organ to a organism from mutations goes far far beyond the possible mathematical probability (10 followed by 50 zeros).

Darwin itself wasn't sure its own theory and he always used "IF" when he referred to his theory!

Isn't all this convincing???!!!

Nowdays scientists use different kind of expressions to refer to the same thing, and this makes it confusing. I think that these two concepts that you mentions are the light-depended and the light-independent phase. The first one requires the presence of the pigment clorophyl, which has the ability to attract light rays. The light dependent phase happens in granums (which are a group of thylakoilds put one on top of other), and the light independent phase happens in the space between granums, and that space is called stroma.

I hope this is usefull.

DraZ

Lately I've heard an idea which really made me thought! Three inches in Earth are equal to three inches in Mars, Jupiter, Pluto, Saturn wherever. But three seconds in Earth are not equal to three seconds in Mars, Jupiter, Pluto, Saturn wherever. And few physicist now believe that there got to be some equations that can be used to measure the velocity, acceleration without having to consider time. So this kind of thinking leads to something that's called "NO TIME"!!! And that's weird. That's impossible actually. As you all know the entire universe is four things : time, matter, space and energy! Or it might be better to sat the universe is made of two couples energy-space and time-matter. And excluding any of them is ABSOLUTELY IMPOSSIBLE because that would cause the exclusion of the three other. You see, time stands to matter as space stand to energy. You might find this confusing but it actually is not, it's very simple! Now let's take a closer look!

All out current equations that we use to measure velocity, acceleration, the amount of motion etc, all these equations have time integrated within them. And why is that?! That is because every single event that happens in this perfect and endless universe happens through time. Even the Big Bang itself is thought to have happened in the presence of time ("imaginary time" - Hawking Model). So there is not a single event that can ignore time. And why I said "time is to matter as space to energy"?

According to Einstein's equation E=mc2, when a body reaches the speed of light, then that body is one the limit of it's energy (the largest energy that body is able to produce). And again according to Einstein, when a body reaches 99% of the speed of light, then the time dilation is infinite, that means no time. So as we can clearly see, when a body reaches the full speed of light, that body (as matter) is actually converted into energy and it has no time (as it has reached more than 99% the speed of light) so it only moves though space. But so far, nothing but light has reached the speed of light so we can't experiment, neither observe such conversion (time-space ; matter-energy).

And if someone makes it find an equation using which we can measure velocity ignoring time, then I really want to see it.

This year, we've been learning about elements one by one at school, and the one I really find interesting is kalium (K). Its characteristics just fascinate me, and I really feel that I really must get some (as I've been thinking for its use). So could anyone please tell me how can I get kalium in a nice, economic, easy way?

Hi!

I've also been dealing with these kind of equations recently and sometimes they can be tricky! The equation that you have typed in called "the neutralization equation". That is because the substances formed have pH neutral [pH(NaCl)=7 ; pH(H2O)=7]. And to decide if the reaction is neutralization or the pH scale is acidic or basic, we have to know a few rules for hydrolysis. If strong acids(HCl, H2SO4, HClO4 etc) react with strong basis (NaOH, LiOH etc), then the pH=7, which means neutral. If strong acids react with weak basis (BeOH), then the pH<7, which means acidic medium. If weak acids (CH3COOH, HF, H2CO3 etc) react with strong basis, then pH>7, which means basic medium.

I hope any will be useful to you..

DraZ