Animations

This is where there are basically no rules about topics, or off-topics. Discuss things here of fleeting interest.
Forum rules
Here, you can discuss anything (well, anything legal and not offensive) you want to. Use this for gassing about any half-baked theories, general getting to know one another, and other things that as someone once said, should be forgotten after awhile. This sub forum is set to auto-remove threads that haven't been posted on for a couple weeks, emptied like the office trash can. Almost anything goes here, the idea being to keep the other forums and threads more on topic but in a maximally friendly way. If anything actually worthwhile should wind up here, let me know and I will make it immune from being removed.

Animations

Postby JonathanH13 » Tue Apr 26, 2011 10:23 am

Some recent animations that I've been playing with - this is for an 'explaining fusion' documentary; any suggestions welcome...



User avatar
JonathanH13
 
Posts: 53
Joined: Tue Aug 10, 2010 3:20 pm

Re: Animations

Postby Doug Coulter » Tue Apr 26, 2011 10:58 am

Very interesting, and in fact, I've been doing this in my head lately (coincidence?) - in both the classical model you show (discrete nucleons) and attempting to "get" the wave-function model too, which is a lot tougher, for me. For an example, see the picture in this [urlhttp://www.coultersmithing.com/forums/viewtopic.php?f=47&t=304]book review[/url].

I do actually have a suggestion on this that might lead to some further insight.

First remember there are 3 possible pathways, and that rare one has 4x the energy output and nothing bad as residue. If I can't do that one, I'm disappointed, and might rather do p->Li or something else with similar energy and outputs -- helium, kinetic energy and photons. I believe that all are very nearly all cross section data is based on "random" approaches of the particles since no one has really worked on how to do this any other way; which to me shouts LOW HANGING FRUIT.

Edit: To expand on that thought a little bit, let me make the assumption that it's not just proximity/time that controls whether a reaction takes place,but orientation, and perhaps spin (not the kind they talk about in wavefunctions maybe, but plain old rotation around some axis). Now, if a particular approach "vector" is the only one that would produce a reaction, even if the actors are in close proximity for awhile, would that not give a lot deeper understanding of why cross sections are what they are? Suppose for low cross section reactions that things simply have to be just so for the reaction to take place, and out of random selection of approach vectors, this is a rare occurrence -- that would explain the low cross section quite well. In fact, given nonuniform distribution of charge in some nuclei, which would put forces on them as they approach, nature may tend to make the reaction less likely through coulomb interaction as the nuclei approach and the charges repel -- unless they were spinning "just so" that at the crucial moment of closest approach, the spin overcomes the coulomb forces trying to reorient the actors the wrong way for reaction. Thus, one might get a handle on how to vastly increase the cross section by prepping the particles on the way in so that when they get close, they're aimed right in more than just the ballistic sense, but also in their overal approach vector (or would that be a matrix?).

So, it might make sense to do time-reversal. Start with an He, and show it breaking up into two deuterons, for one example. Why bother? Well, physics is supposed to be time-direction-invariant (if various other signs are flipped), but we humans don't do that so well.

Here's what I'm thinking -- if we looked at the breakup of an He in reverse, a tiny amount of time "after" the breakup (assuming the simulation is accurate in all the force interactions) would show us the ideal conditions to get fusion when time runs the normal direction....and the trick should work for the other two pathways too, and again, show us the orientations of the approaching particles that lead to that pathway so we can try to "make it so" in our operating conditions.

Harder than what you've done already, but a worthwhile use of computers in this quest I think.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 3515
Joined: Wed Jul 14, 2010 7:05 pm
Location: Floyd county, VA, USA

Re: Animations

Postby chrismb » Tue Apr 26, 2011 1:46 pm

I think you're both being very 'deterministic' in your analysis of fusion.

Johnathan - I think they are fine 'schematics' of the process, for explanatory purposes, but if there were to be a more realistic 'reality' I think it would tend to look more like two water drops coming together in zero g. They would merge, wobble about for a few picoseconds, then pieces might fly off.

Doug, in terms of 'reversibility of time', I think it is 'mechanics' that are reversible but 'physics' tends to have a direction of time ... it heads towards the configuration of the most probable permutation of states.

Your description of looking at what happens to an excited He just as it fissions, then doing that in reverse, has hallmarks of great philosophy but little practical value - (IMHO, of course!). Whosoever does actually twiddle with the knobs of the universe does, indeed, do his job by shaking on dice all the time. Just consider this - if this was a rational way of deducing how to form that excited He in the first place, then why is it that radioactive decay is 'random'? If you had an atomic microscope (as per John's video) the you could sit and watch a U-238 atom and it might split there and then whilst you look at it, or it could take trillions of years. On average, with a large enough sample, statistics can provide data that is probabilistic as to whether or not an atom is likley to do what you expect it to do, over a given timescale.

{If the situation were as determinstic as you rely on to consider 'reversing' the process, this would mean that you are saying you could examine a given atom in some way [not yet understood, but there is some way] and state when it was going to decay, and how. Well, this was the view of Descartes many years ago, that if we know enough about the moment now then we'd be able to predict the future, but quantum mechanics says something very different to this.}

The process of that excited He is, I say, much the same and it is random and probabilistic in nature - though it happens on a time scale some 20 orders of magnitude quicker than the U-238. It might give up an alpha, or a double beta, or fission. Your argument is that how it was formed up a billion years earlier will determine when it decays, and by what decay path.

Now, I don't see how its formation and its decay are related. Is that different in an He from a D+D fusion? Is there some other reason to think it is not probabilistic but has been determined, 'destined', according to the way things happened prior to the fusion event? Well, I guess that question is to play for. You feel your experiments already point to it being so, whereas I tend to think on that time- and length-scale, all is a random blur of matter and energy that it is anybody's guess.

Science is, in my definition, when you show something in the physical world that no-one else expected (viz. did an experiment that no-one else could be bothered to do, and show something unexpected). So if you can show this conclusively, then I would be the first to declare you'd've done some real science here.
chrismb
 
Posts: 620
Joined: Thu Aug 05, 2010 6:32 pm

Re: Animations

Postby JonathanH13 » Tue Apr 26, 2011 4:47 pm

Thanks for your comments. First off, I should say that these animations are necessarily deterministic, in order to explain fusion to the general public. So they have to be simple. Although, when I started creating them, I was faced with a decision - at what level do you draw the line? So it looks like two animations are in order - one deterministic, the other quantum. At the moment the line is drawn for me by my inability to control the animation software quite as well as I would like - what you see is the result of about 4 hours of skimming YouTube tutorials :)

Anyway. I did try to show how a particular orientation and spin may contribute to a successful/particular reaction - for example, in the tritium reaction, the ions are 'rotating' opposite to each other, and they strike 'side on' with respect to the 'neutron-proton axis', whereas in the other animation, they meet 'proton-to-proton', and are repelled. Now I know that this is all vastly simplified and speculative, but, interestingly, to create these animations I had to start in the middle of the time sequence, with the helium atom, and then work backwards towards the deuterium ions, in order to get everything to meet up correctly. So I do think that there is some merit in that train of thought. For example, in order to show the energy that has been created, the proton races off faster than the tritium ion, demonstrating that the loss in mass appears as an increase in kinetic energy. So this got me thinking that if we wanted to make deuterium from protium and tritium, then it would make sense to have the protium moving faster than the tritium (does that make sense?) I guess you could test this beam on beam, and measure whether faster moving hydrogen ions yield more, less or the same amount of deuterium.

Now I know this is not 'how it is' at that level. We know that it is all fuzzy probability distributions and other disagreeable quantum misbehaviour. Whether we think of particles or wave functions, we know that the ions are actually neither, and the essence of what is really going on, is likely to be impossible to visualize. Nevertheless, these 'wavicles' do have specific properties, and if we can define them and measure them (even if only probabilistically) then we can work towards controlling them.

Unfortunately to make these simulations force accurate you really have to move towards Java applets...
User avatar
JonathanH13
 
Posts: 53
Joined: Tue Aug 10, 2010 3:20 pm

Re: Animations

Postby Doug Coulter » Tue Apr 26, 2011 6:07 pm

I don't have a complete argument that disproves the randomness of quantum theory, and I can't easily think that one exists at all, though some of the math does cause me some distress -- the loss of the complex phase and just keeping an amplitude probability is verboten in practically every other use of complex numbers -- there has to be a problem there, and I've never seen that justified to suit me (or really, at all). Information is thrown away when you only take the magnitude of a complex number and ditch the phase, but that's just what the wavefunction math does at the end. If you did that with say a frequency spectrum (such as from a fourier transform) you'd find you couldn't inverse transform and get your data back as the same waveform anymore. It would look "probabilistic" in that case, depending on whether you plugged in zeros for the imaginary parts, or randomized the phase -- but in both cases, this arises due to something you did, not nature. Seems to me the derivation of the wave function does just this, then complains about not having all the info. Well the step where it's tossed in the trash is quite obvious to someone who's done a lot of signal processing. Oh and by the way, in nearly all cases -- an inverse transform with missing phases gives just the same probability density function as getting it correct does...another hint of how something can be "almost right, but not really right". Only in the case of certain waveforms is this not true -- think square waves. We used this in electronic intelligence to compute SNR on unknown signals, actually and the type of modulation didn't matter and the thing was accurate, helping the crypto guys a lot to know when the data might be garbage due to low SNR so their code breaking was a lot easier.

I do have this experimental data that seems to show that certain reaction pathways are favored under different conditions over what seems like eons on that timescale. That data I showed where for awhile, the neutron counters were going nuts, but not so much the gamma spectrum, then the reverse, for around 250 milliseconds at a time, back and forth. That's quite some hint. You might not believe my data -- but I do, I saw it and more than once, and I will replicate it when I feel the need to, particularly now that I have better gear to quantify it with more accurately. I can't whine if someone doesn't believe my report of one experiment, or a couple, but having built all the gear and knowing what its strengths and weaknesses are, I believe it myself. This was shown during an exceptionally stable run, which makes sense, else I'd never have seen it. With nuclear frequencies in the 1020 to 1022 range, anything lasting a quarter of a second means that things were drifting extremely slowly to get in or out of phase conditions to last a perceptible length of time, or so one would have to assume. So all the observations do make a little sense when taken together. Further, the oddball pulse mode we've seen super high Q in also indicates that when things are kind of coherent, we see something that would tend to indicate that things are different before thermalization sets in, another hint.

Randomness is invoked far too often to excuse ignorance. For example, Brownian motion isn't random, just looks that way because you don't know all the vectors of motion of every molecule in that cup of tea. (and it was recently observed with a quick enough camera to even see the individual impacts and reported on all the science boards) Uranium can be photo-fissioned due to stretching the nucleus into an unstable shape with EM energy. The cross section is low (we think) because perhaps it's hard to get a photon in the right polarization to hit a U nucleus which is in the complementary vibrational state to absorb it, since that is "random" because we can't control that (so far as we know) YET. Although Brownian motion tends to follow the "drunkard's walk" in a hot liquid, that doesn't mean you couldn't carry a particle along in a laminar flow -- it's just a different thing, and the existence of one doesn't make the other impossible, or even unlikely.

I won't say god never plays dice, though I think of it a good bit differently than either Einstein or Schroedinger - I like the idea that it's space-time that's quantized better, and when you play with the gravity math, so does Planck, or it seems so - this is where the string theory guys are heading now; but I think all too many lazy thinkers use that as an excuse inappropriately, and get away with it because for example, only recently has it been possible to even think about orienting particles this way or that, and by then all the money was going into sub-nuclear studies. Even a D nucleus is large and energetic enough to have some classical attributes outside of the "probability" stuff from the wavefunction alone. It can be hard to see the quantum effects on a large body like a baseball, but they're there. Ditto classical effects on a small one -- they're still there, just muted under the circumstances. The thing is, unless you consider a D to really be a fuzzy ball with net charge of one but mass of two (roughly) then it does have a discrete proton and neutron at least some of the time, and acts like it. This is certain in larger nuclei.

There is plenty of evidence this matters. MRI wouldn't work if you couldn't do this at some level, for example. At the molecular level, it's obvious that molecules and rotate, bend and stretch and we can measure the resonances that this produces. Of course molecules are much bigger than nuclei, and subject only to EM forces (we think at present), but then many models of nuclei that work out well are based on the same things -- the liquid drop model and the shell models are examples, and the latter is so terribly like the same situation as the electron shell model it's not funny -- magic numbers and all. This is all in physics books that I wish more would read -- I'm neither making it up nor taking credit for it. Halliday is probably the simplest one for that.
Though we think of the strong force as having asymptotic freedom within a nucleon, that doesn't utterly invalidate the possibility of the spring-mass model either. And if we assume that at least some times a D looks like a joined proton an neutron (as the wave function photo from the book review seems to show), not just a fuzzy ball, we could consider that a classical explanation would cover it at least somewhat.

Various nuclear transitions have "selection rules", and have transitions all the way from disallowed to hyper-allowed. That should be a big hint it's not all random at all.
And in fact, all I'm doing is saying it would be nice to take all the known rules into account, and by going backwards, figure out how to do it going forwards. Although He is almost too simple for this, it's the one of interest in the current case. It's very unlikely for example that an He would be strung out in a line ppnn, but globed together in a more compact way, as the lower energy state in normal conditions. Ditto especially a U atom. It's possible in the latter case for the protons not to be uniformly distributed, and for it to have dipole, quadrupole and higher moments. Hf (one of the isotopes) is reputed to be able to stay in an excited, but metastable state for long periods of time, then finally emit a gamma much later.

So, if these selection rules exists, and they sure seem to do so, then going backwards to take a look makes a lot of sense to me. If an He only has certain ways to break up into deuterons, for example, you'd only get fusion to He from deuterons if the states of the inputs were correct -- and the fact that this is unlikely explains the low cross section with random inputs quite neatly.

To say it's all utterly random is to fly in the face of a lot of worked out standard model science, something I'm not willing to do at this point, because I believe that most of the experimenters haven't told me lies or been dead wrong. I think this area is merely not well enough explored yet, and that doing so might lead to good things -- and that in hindsight, if I'm correct, it will all fit into the current models just fine, in hindsight. No magic, or any vast enhancement to the existing theory would be required for me to be correct here, in other words.

And yes, I understand Jon was just trying to make an illustration for newbs to understand what's going on (might be better if you showed the gluons, but then again, that'd make it pretty complex and faze them), but it seems three of us -- myself, Curtis, and Jon have all been thinking along very similar lines here for awhile, and where there's smoke....you just never know, and I think it's worth investigating in more detail -- to prove it either way. If we get "lucky" then there's the keys to the fusion kingdom, if not, well, it's still better to know than spend endless time working with various slight refinements in technique and configuration until we find a "casino edge" that makes us win despite even odds.

How could you say something can't be so if it's never even been looked at? I'm not now and never did say I surely have the answer. What I have is a tantalizing hint(s) that there's something here worth investigating, and the beginning of an experimental program to do just that. If and when it proves out, or not, of course it will be reported. That's the basis of science to me -- hypothesize, then prove or disprove.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 3515
Joined: Wed Jul 14, 2010 7:05 pm
Location: Floyd county, VA, USA

Re: Animations

Postby Joe Jarski » Tue Apr 26, 2011 7:56 pm

Nice animations Jon... and another good discussion. I don't want to derail this whole thing with a simplistic observation, but I find it interesting that the probability of D-D fusion resulting in 4He is so incredibly low when when alpha particles are so common in nuclear decay. Heavier atoms find it easy to eject an alpha particle which seems to form a relatively robust particle within itself, but the likely hood of the subatomic particles being able to rearrange themselves into an "alpha" particle arrangement during D-D fusion is nearly non existent - it would rather fling of a proton or neutron instead.

I think characterizing fusion and decay as a totally random event is an oversimplification of outside factors that haven't been identified yet. While unconfirmed, decay rate change leading solar flares for example. If I can control enough of the variables in flipping a coin, I can certainly change the outcome of the flip. If you told me a year ago that you could pump down a vacuum chamber, apply a high voltage to it and get something the size of nucleus to run into another one at *any* rate, I would have thought it was impossible.

A funny side note... A while back I was trying to get a feel for the "atomic" scale of things and thought about making scaled up H or D atom just for fun (crazy - I know). I gave up when when I realized that a 10 mil proton would put the electron shell at somewhere around a 30 ft. :o
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Re: Animations

Postby Doug Coulter » Tue Apr 26, 2011 8:43 pm

Joe, you just managed a good concise statement of what I was trying to say, actually. I have to admire the better brevity ;)

Halliday has it that alphas are especially stable (so does the shell model) - we know this from the binding energy stuff, and are perhaps sort of pre-formed in larger nuclei, kind of bouncing around in there till one tunnels out in alpha decay (the magic numbers for stability/instability reinforce this idea). Astonishingly low probability -- everything else has to be just right, since a given "proto alpha" seems to present itself at the tunneling barrier at around 1020 Hz or so, while most alpha emitters obviously have much longer half lives - Thorium being a great example with it's super long life, U coming in a little quicker, or a lot depending on which isotope of U you're working with.

I did the sense of scale thing too for lithium in solid form .. There it works out to golf balls 1/3 of a mile or so apart. I actually found that inspiring, as I have a couple rifles that can reliably hit a golf ball that far away.. and it's a lot more efficient than a shotgun would be as regards powder and lead. Yet even beam experiments are shotguns compared to some of the ideas I began with.

As you say, a coin flip is random -- not necessarily if someone really knows how to flip them. In fact, even if not, it was recently reported that coin flips are fairly non random - they tend to land on the same side that was up when a human flipped them, and NFL teams actually use this when calling the toss now!

What I'm looking at is a couple things. Simplistically and pure-classical-mechanically, the protons and neutrons in the fusion products (what ever the reaction pathway is taken) are arranged in some way (or possible set of ways). Would it not be better if the stuff we're trying to shove together was already oriented correctly so it took least-effort to assume the final state we want? Although common sense doesn't alway apply in the quantum field, it does sometimes. And I'm convinced this isn't purely quantum in the sense that classical mechanics don't apply at all.

Further, there are all these conservation laws that seem to pretty much always be observed, which generate the selection rules for how something can decay, assuming you have something that can decay. These work both directions -- so should we not go at this from that direction? If the particles entering have states that don't add up to the desired exit state, it's not going to happen, but if they do, you've got a chance. Maybe a better chance than if you just toss things together at random, which is the way all existing reaction cross sections were measured -- a sum of all the random probabilities. I have to believe that if something has say 6 degrees of freedom per particle, but only one way satisfies all the conservation laws for the product, then by golly, we should only invest energy into accelerating those particles that even have a chance at giving the desired result.

Here's a few words from Halliday on this issue for gammas, but similar considerations apply to all other sorts of reactions. It's just that they're kind of spread out all over the book and hard to give a nice single scan here. The idea is fairly simple -- if we know what we want to wind up with as regards all these conserved quantities, that'd better be what we put in to get it to "go" the easiest and with highest probability.
Hselection.gif
Halliday on some selection/conservation rules


I can only wish that everyone had a copy of this fine book. A little dated, but you know, when he goes out on a limb and predicts the future (from his point of view) -- he was almost always correct. The guy had a great intuition.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 3515
Joined: Wed Jul 14, 2010 7:05 pm
Location: Floyd county, VA, USA

Re: Animations

Postby Joe Jarski » Wed Apr 27, 2011 8:10 pm

LOL, thanks. I don't always communicate a logical point, but I usually have the brevity part down.

My copy of Halliday's book must be a different edition than yours. At any rate, I need to get back into it - I only got through 60 pages or so before being sidetracked.
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Re: Animations

Postby Doug Coulter » Wed Apr 27, 2011 8:29 pm

I missed something you said, short though it was, but it's key, I think. Since the alpha is one of the super stable chunks (magic numbers, binding energy and so forth) yeah, why is it it's the rarest outcome of DD fusion anyway? I can suppose a couple of reasons, but they'd be wild guesses based on how geometry had to adjust for two things that are PN to adjust to the mechanical arrangement in an He that gave that minimum excitation energy. Or it could be all that selection rule stuff, as in "you can't get there from here, at least directly".

I mean, look at the more normal fusion products from DD -- none are stable except the proton, and it has no binding energy. T? So unstable it decays on its own. 3He -- rare in nature, hmmm, and easy to make go bang too, with a neutron. Neutrons themselves aren't stable outside of a bound state. So, what gives here -- what are we missing? Why is nature not taking the usual course of energy falling down hill the farthest it can, right off? There are some cases of that in plain chemistry, maybe I'll go bury my head into steric hindrances or something and see it there -- oh, that's what I just said above, didn't I, when I mentioned geometry? Here we have other possibilities than just mechanical hindrances though, and I need to go do some homework on that one.

I bet when we win this battle of subtlety over brute force, it's going to be a major head-slap and face-palm moment. We're going to be sayin' "gawd, how did I not see that for so long?"
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 3515
Joined: Wed Jul 14, 2010 7:05 pm
Location: Floyd county, VA, USA

Re: Animations

Postby Joe Jarski » Wed Apr 27, 2011 9:30 pm

My wild guess and current line of thinking is probably similar to yours... that the 4He nucleus has a "stable" geometric structure that the sub-particles like to be arranged in. However, the P-N orientation during D-D fusion that makes the transition to 4He easy must have a really low cross section, for example the approach may be nearly P on P where the coulomb forces are highest. The other side of that is that a N on N collision would *in theory* be easier due to less coulomb interaction, but requires such massive reordering of sub-particles to get to 4He that it "decays" by P or N emission before the reordering can be completed.

I'd put more weight in the process being totally random if a P was just a ball of +1 charge or N a ball of 0 charge, but its already been demonstrated that the particles have polarity... Call the Hadron in the vacuum... heads or tails?
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Next

Return to The water cooler -- disscusions about anything

Who is online

Users browsing this forum: No registered users and 3 guests

cron