Quantum Mechanics
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I am 1 graduate course away from a phd in Quantum Mechanics.... Dictionary.com says: ran⋅dom /ˈrændəm/ Show Spelled Pronunciation [ran-duhm] Show IPA –adjective 1. proceeding, made, or occurring without definite aim, reason, or pattern: the random selection of numbers. 2. Statistics. of or characterizing a process of selection in which each item of a set has an equal probability of being chosen. o.k. in order: :doh: 1; quantum particles behave according to their "nature" they usually are "aimed" (at the lowest local energy state), the reason is entropy(usually) and they have a pattern(albeit poorly defined: See Heisenberg uncertenty principle.. which basically says that if a particle is then it exists somewhere in the universe, but you will never know where it is... ) 2; the positions of any given quantum particle can never be know, however it is to all reasonable approximations residing in bounding frustrum in space-time(its physical extent..from a certain perspective). However the exact probability that a quantum particle is ever in any position is 0 (i.e. it doesn't exist). [Check this out^] so to answer your debate: (if you believe in string theory and that there exists a grand unified field theory) everything in the universe is pre-determined by something that is so complicated that we percieve it as random, although were we capable of peering into an alternate dimension we could (knowing absolutely EVERYTHING) possibly account for all particles(assuming that that universe exists of only one sub atomic particle.. (n=9)^27 after that (n=81)^27 the calculation becomes .... unstable or simply to big to compute... but even if you could compute it it wouldn't matter because that universe would have already cooled and you would need to recompute the answer... (if you only go to quantum theory) then yes there is randomness in this universe (below the quantuum classical barrior aproxamatly less then 200 microns ) (if you believe that newton was the last scientist ever) then no there is no randomness. your finite machine depend on scale if it's "pointer" is >200 microns your friend is absolutely correct(sorta) if your below the threshold but still greater then one particle(in a universe)
Changing the subject, sort of, in that I've been out of the line for some number of years and certainly good answers should exist. When last I was in the world of science, femtosecond laser pulses had just been created. This gave me a problematic thougth: A pulse could be sufficiently short in duration to be less that necessary to represent a single wavelength-unit (or even a single half-wave). I wasn't able to properly fathom the implications of a wave that didn't "represent itself" with its own (defining?) properties. Several physicists were handy (alas, the DOE facility I worked at was near WV University). Most were unable to understand my question of "what does it mean if the 'physical/measurable' length of a pulse of light was less than half a wavelength. One, however, did give me some solice: he said that it was simply that the wave-theory/description of light currently in use breaks down at this point. I've been somewhat empty inside ever since. Any insight on your part? Keep it gentle - it's been decades - and I wasn't a quantum chemist to begin with (although I did grad work in multi-photon processes).
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment. Sadder still, if that's where you need to find it." - Balboos HaGadol
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Your friend would probably lean towards Bohmian Mechanics[^]. Sorry if there will be a repost.
That was a very good article, I recommend it. I zoned out on the math, but it seems to explain the double slit experiment quite nicely without all the usual philisophical nonsense.
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Chris Trelawny-Ross wrote:
that doesn't change the fact that to our perceptions we have a distinct future and past.
Please help me know something about knowing my distinct future - I need to make some vacation plans and don't want to buy vacation insurance.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment. Sadder still, if that's where you need to find it." - Balboos HaGadol
Balboos wrote:
Please help me know something about knowing my distinct future - I need to make some vacation plans and don't want to buy vacation insurance.
Not being God, I'm really not in a place to help you with that. However, here's what you can know about your distinct future: it's distinct, and it's yours. :-D And, truth be known, you really don't need to know anything at all about it about it (not even that it's distinct, and yours). It'll happen to you whatever you know, or don't know. So, make your vacation plans, or don't make them, and buy, or don't buy, your vacation insurance, not on the basis of what may or may not happen in the future, but on the basis of the difference it makes for you right now. Because the future that you want to happen, and the future that you think will, or may, happen, may not happen. And then where would you be, having made plans for a future that didn't happen?
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Balboos wrote:
Please help me know something about knowing my distinct future - I need to make some vacation plans and don't want to buy vacation insurance.
Not being God, I'm really not in a place to help you with that. However, here's what you can know about your distinct future: it's distinct, and it's yours. :-D And, truth be known, you really don't need to know anything at all about it about it (not even that it's distinct, and yours). It'll happen to you whatever you know, or don't know. So, make your vacation plans, or don't make them, and buy, or don't buy, your vacation insurance, not on the basis of what may or may not happen in the future, but on the basis of the difference it makes for you right now. Because the future that you want to happen, and the future that you think will, or may, happen, may not happen. And then where would you be, having made plans for a future that didn't happen?
I'm far too optimistic to think that the future is preordained. For that matter, it would seem to me (as a human, at least) that it is not in G^d's interest to pre-ordain the future. If so, what would be the point of creation? True worship requires true free-will. Free-will implies taking on the responsibility for one's own actions - and taking action to change ones situation because it can be done. Much as I like the Vonnegut/Tralfamadorian description, it's only for entertainment purposes. The only thing distinct about anyone's future is that it's theirs. What comes of it is anybody's guess. Your born; you live; you die. The rest is history - but only after the last step. Hey - cheer up. We're all just worm-bait on the hoof.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment. Sadder still, if that's where you need to find it." - Balboos HaGadol
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Changing the subject, sort of, in that I've been out of the line for some number of years and certainly good answers should exist. When last I was in the world of science, femtosecond laser pulses had just been created. This gave me a problematic thougth: A pulse could be sufficiently short in duration to be less that necessary to represent a single wavelength-unit (or even a single half-wave). I wasn't able to properly fathom the implications of a wave that didn't "represent itself" with its own (defining?) properties. Several physicists were handy (alas, the DOE facility I worked at was near WV University). Most were unable to understand my question of "what does it mean if the 'physical/measurable' length of a pulse of light was less than half a wavelength. One, however, did give me some solice: he said that it was simply that the wave-theory/description of light currently in use breaks down at this point. I've been somewhat empty inside ever since. Any insight on your part? Keep it gentle - it's been decades - and I wasn't a quantum chemist to begin with (although I did grad work in multi-photon processes).
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment. Sadder still, if that's where you need to find it." - Balboos HaGadol
In this case it is best to think of them as particle emitters. Short pulse lasers do not guarantee that a particle will be released, they just limit the number of particles which will be released. Which when you think about the sparseness of matter is really not a lot of light, so in the end for the short pulse laser, really only a few molecules are hit by light. Short pulse lasers can be used for exploring the excited states of a compound to get an idea of what types of transitions the compound undergoes as it gets excited and the resulting relaxations. think of a particle in a box (textbook) now make it a thousand particles in the same box(a light capacitor if you will) now have a very fast assistant open a side, and close it again you may find one or two of your "trapped" photons have escaped, it doesn't have to do with wavelength, it has to do with intensity, and shutter frequency. because as you know the "light"(or electrons, molecules etc) can be whatever wavelength you want it, it is just that if it becomes to long it will no longer behave quantum mechanically. the reason that short pulse lasers are needed is because the relaxation emissions happen on that same or shorter time scales, so you need to turn it off immediately after you have an excitation. what you get (in the bulk) is a distribution of molecules in various states, transitioning between them at random intervals, emitting a spectrum. which basically tells you everything you really want to know about the molecule(physically). wave packet is he name associated with the QM calculations regarding this. wave packet methods, are similar in essence to a femto/atto second pulse (it is a single photon).. treating the wavefunction using wave packet methods you get a similar result to the low intensity excitations of short pulse lasers. the wave packet(essentially a single photon) is a fun thing to play with, at times(using certain formulations) the thing will "be" a particle, and at others it will "be" a wavelet. in fact finding the solution requires (best shortcut) cycling between the two states.
while(notdone)
{
while(notconverged_P)
{
treat as particle....
}
while(notconverged_W)
{
treat as Wave....
}
}
ReportSuccess()Particle wave duality... obeys perhaps the same geometry as the uncertainty principle(they are after all fairly closely linked :laugh: ) It is both but rarely if ever at the same time. so if you can't wrap yourself around how
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In this case it is best to think of them as particle emitters. Short pulse lasers do not guarantee that a particle will be released, they just limit the number of particles which will be released. Which when you think about the sparseness of matter is really not a lot of light, so in the end for the short pulse laser, really only a few molecules are hit by light. Short pulse lasers can be used for exploring the excited states of a compound to get an idea of what types of transitions the compound undergoes as it gets excited and the resulting relaxations. think of a particle in a box (textbook) now make it a thousand particles in the same box(a light capacitor if you will) now have a very fast assistant open a side, and close it again you may find one or two of your "trapped" photons have escaped, it doesn't have to do with wavelength, it has to do with intensity, and shutter frequency. because as you know the "light"(or electrons, molecules etc) can be whatever wavelength you want it, it is just that if it becomes to long it will no longer behave quantum mechanically. the reason that short pulse lasers are needed is because the relaxation emissions happen on that same or shorter time scales, so you need to turn it off immediately after you have an excitation. what you get (in the bulk) is a distribution of molecules in various states, transitioning between them at random intervals, emitting a spectrum. which basically tells you everything you really want to know about the molecule(physically). wave packet is he name associated with the QM calculations regarding this. wave packet methods, are similar in essence to a femto/atto second pulse (it is a single photon).. treating the wavefunction using wave packet methods you get a similar result to the low intensity excitations of short pulse lasers. the wave packet(essentially a single photon) is a fun thing to play with, at times(using certain formulations) the thing will "be" a particle, and at others it will "be" a wavelet. in fact finding the solution requires (best shortcut) cycling between the two states.
while(notdone)
{
while(notconverged_P)
{
treat as particle....
}
while(notconverged_W)
{
treat as Wave....
}
}
ReportSuccess()Particle wave duality... obeys perhaps the same geometry as the uncertainty principle(they are after all fairly closely linked :laugh: ) It is both but rarely if ever at the same time. so if you can't wrap yourself around how
Still leaves me a bit empty inside. My available timescale, at the time was ns - and it was fun being able to resolve a pulse of light that traveled a maybe 30cm further on our scopes. Faculty, at real universities were resolving ps. This was more interesting to me because: I had done IR Isotope separation (10 um 100+ ns pulses of ca. 1J)**. The goal was to synthesize a molecule with metal-ligand* bonds that were withing the tunable range of a CO2 laser (which had to be home-made at the time). By then (and this is the relevant part) it was determined that laser photochemistry would not allow the selective cutting of bonds to form chemistry: due to the very fast (ps) scale of intramolecular vibrational energy transfer, the weakest bond always broke (ergodicity)***. If the pulses were faster, then the bond-specific scission would be feasible. The problem, of course, is that these are multi-photon processes and take huge photon-fluxes to accomplish: and the faster the pulse, the more likely one ends up with a dielectric breakdown (plasma-time). That, itself, lends the possibility of shortening the pulses, such as in inertial confinement. Back to fs: wave-packet concept seems to have hybridized particle and wave descriptions. Other than for the sake of your discussion, are you sure about the single-particle description. I seem to remember that once the pulse was generated (by a very clever mechanical procedure), it was sent into an amplifier cavity to get a little gusto out of it. Perhaps that was just for ps. Another thought that always clouded the issue for me was even speaking in terms of the wavelength - which for this short of a pulse duration was extremely uncertain. Passing a pulse through a prism gave a mini-rainbow. Actually through almost any medium that retarded the wavelengths differently, even with parallel faces (which I thought was absolutely cool). To resolve the (even faster) intramuscular processes, one must be able to probe them - which I presume implies resonance with, if not the process of interest, then to a precursor or elsewhere in the (reaction) chain that could be perturbed. The resonance, however, begs a wavelength match - and usually a pretty damn good one. But the short pulses are sort-of white. And if it's not in resonance****, except for the most trivial systems, how would one know what one was probing? So this is where my admittedly limited chemistry viewpoint of all of this keeps getting pummeled. * U-O in this case - yup, enri
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Still leaves me a bit empty inside. My available timescale, at the time was ns - and it was fun being able to resolve a pulse of light that traveled a maybe 30cm further on our scopes. Faculty, at real universities were resolving ps. This was more interesting to me because: I had done IR Isotope separation (10 um 100+ ns pulses of ca. 1J)**. The goal was to synthesize a molecule with metal-ligand* bonds that were withing the tunable range of a CO2 laser (which had to be home-made at the time). By then (and this is the relevant part) it was determined that laser photochemistry would not allow the selective cutting of bonds to form chemistry: due to the very fast (ps) scale of intramolecular vibrational energy transfer, the weakest bond always broke (ergodicity)***. If the pulses were faster, then the bond-specific scission would be feasible. The problem, of course, is that these are multi-photon processes and take huge photon-fluxes to accomplish: and the faster the pulse, the more likely one ends up with a dielectric breakdown (plasma-time). That, itself, lends the possibility of shortening the pulses, such as in inertial confinement. Back to fs: wave-packet concept seems to have hybridized particle and wave descriptions. Other than for the sake of your discussion, are you sure about the single-particle description. I seem to remember that once the pulse was generated (by a very clever mechanical procedure), it was sent into an amplifier cavity to get a little gusto out of it. Perhaps that was just for ps. Another thought that always clouded the issue for me was even speaking in terms of the wavelength - which for this short of a pulse duration was extremely uncertain. Passing a pulse through a prism gave a mini-rainbow. Actually through almost any medium that retarded the wavelengths differently, even with parallel faces (which I thought was absolutely cool). To resolve the (even faster) intramuscular processes, one must be able to probe them - which I presume implies resonance with, if not the process of interest, then to a precursor or elsewhere in the (reaction) chain that could be perturbed. The resonance, however, begs a wavelength match - and usually a pretty damn good one. But the short pulses are sort-of white. And if it's not in resonance****, except for the most trivial systems, how would one know what one was probing? So this is where my admittedly limited chemistry viewpoint of all of this keeps getting pummeled. * U-O in this case - yup, enri
Balboos wrote:
due to the very fast (ps) scale of intramolecular vibrational energy transfer, the weakest bond always broke (ergodicity)***. If the pulses were faster, then the bond-specific scission would be feasible.
alas we are still mostly bound by our understanding of the laws of physics.
Balboos wrote:
The problem, of course, is that these are multi-photon processes and take huge photon-fluxes to accomplish: and the faster the pulse, the more likely one ends up with a dielectric breakdown (plasma-time). That, itself, lends the possibility of shortening the pulses, such as in inertial confinement. ... .... To resolve the (even faster) intramuscular processes, one must be able to probe them -
which I presume implies resonance with, if not the process of interest, then to a precursor or elsewhere in the (reaction) chain that could be perturbed. The resonance, however, begs a wavelength match - and usually a pretty damn good one. But the short pulses are sort-of white. And if it's not in resonance****, except for the most trivial systems, how would one know what one was probing?This is why most experiments use pumping, using a couple of tuned lasers, and the calculated(experimentally or en silico) excited states, to make the process more surgical, or alternatively sensitizers which allow the experiment(synthesis) to proceed at lower intensities. Not sure at what your getting at with the resonance comment, most of the muscular (biomechanics) research I'm familiar with is done in an optical tweezers. Where they focus more on Doppler or proximity effects, However those intra-muscular studies I believe use non-native analyte (peptides/intermediate analogs) which show up like a basketball player in a room of Asians...(personal experience :wtf: ) So, to see shifts in such things is made easier by wise choice of how they analyze... (wow so far off the original track!) also talking about the "white" pulse you mention, as long as part of it overlaps with a region of interest you can make it work. These things rarely work out as good in reality as they could on paper given perfect resources...
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Does not the physics of QM provide for "true randomness" in the Universe? I'm debating a friend who seems to think everything is predetermined, period. My argument against, is that his proposal would be a finite machine, one which could be moved either forward or back. Additionally, my argument continues, if true randomness exists, then it can't be predetermined nor undone. Am I incorrect? Any thoughts?
As I understand it QM is indeterministic based on the standard formalisms but it is not possible to rule out deterministic hidden variables theories. However, any such theories must be non-local. There are deterministic interpretations such as David Bohm's and David Deutsch's. So your friend might still be right.
Kevin
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Balboos wrote:
due to the very fast (ps) scale of intramolecular vibrational energy transfer, the weakest bond always broke (ergodicity)***. If the pulses were faster, then the bond-specific scission would be feasible.
alas we are still mostly bound by our understanding of the laws of physics.
Balboos wrote:
The problem, of course, is that these are multi-photon processes and take huge photon-fluxes to accomplish: and the faster the pulse, the more likely one ends up with a dielectric breakdown (plasma-time). That, itself, lends the possibility of shortening the pulses, such as in inertial confinement. ... .... To resolve the (even faster) intramuscular processes, one must be able to probe them -
which I presume implies resonance with, if not the process of interest, then to a precursor or elsewhere in the (reaction) chain that could be perturbed. The resonance, however, begs a wavelength match - and usually a pretty damn good one. But the short pulses are sort-of white. And if it's not in resonance****, except for the most trivial systems, how would one know what one was probing?This is why most experiments use pumping, using a couple of tuned lasers, and the calculated(experimentally or en silico) excited states, to make the process more surgical, or alternatively sensitizers which allow the experiment(synthesis) to proceed at lower intensities. Not sure at what your getting at with the resonance comment, most of the muscular (biomechanics) research I'm familiar with is done in an optical tweezers. Where they focus more on Doppler or proximity effects, However those intra-muscular studies I believe use non-native analyte (peptides/intermediate analogs) which show up like a basketball player in a room of Asians...(personal experience :wtf: ) So, to see shifts in such things is made easier by wise choice of how they analyze... (wow so far off the original track!) also talking about the "white" pulse you mention, as long as part of it overlaps with a region of interest you can make it work. These things rarely work out as good in reality as they could on paper given perfect resources...
ely_bob wrote:
Not sure at what your getting at with the resonance comment,
Muscle Tissue? A very different world, indeed - huge molecules in solid state - from my point of view, nearly black absorbers. To me, a large molecule would be something like water, maybe methanol, H2S, &etc. Such molecules have very discreet states and absorption of energy (at least in the gas phase) require resonance with the transition (and access to the state, such as the ground state to excited state, or, with multiple pumps, excited state to excited state). Examining rates of (slow) processes, such as inter-system crossing, singlet-triplet transitions, etc; or lower energy vibrational probing - and always in the gas phase. Not at all the same scenario you'd observe on a block of meat. I'd imagine the states to be very diffuse. On the other hand, with such closely packed states, the need for some very fast lasers is pretty clear. Memories of real life - where did I go wrong?
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"How do you find out if you're unwanted if everyone you try to ask tells you to stop bothering them and just go away?" - Balboos HaGadol"It's a sad state of affairs, indeed, when you start reading my tag lines for some sort of enlightenment. Sadder still, if that's where you need to find it." - Balboos HaGadol
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My verbage isn't that great, but I think I get my point accross ok... Every action has an equal and opposite reaction. This can be taken as true in any form from an atomic level to a macro level (solar systems and galaxies). As far as I know, you can safely say that each molecule affects the molecule next to it, to some degree, and in the same regard each atom reacts from interaction with other atoms around it. Like a game of marbles, each flick of a marble has an impact on all the other marbles near it; you project the marble with force, and based on so many variables such as gravity, speed, acceleration, mass, velocity, surface area, etc, etc, it hits another marble sending it moving along it's OWN course. Obviously losing energy through other resistances such as friction the second marble may hit a third marble, repeating these effects, but to a lower degree, until all that energy is disipated and the marbles no longer move. You could say that throwing that marble a billion times will NEVER render the exact same results; there will always be some kind of "randomness" associated with the event, and this is completely true. Throw it forever, and you will no doubt never see the same outcome. However, this does not mean that true randomness exists in our universe. Say we were using the big bang as a point of origin for an event. Similar to the marbles, the explosion sends debris, rocks, elements, gasses, energy, etc eminating, rather speeding away from the event horizon heading out into the universe (or as some presume, CREATING the universe itself by expanding at the speed of light). Now at a macro level these bits and pieces hitting each other cause enormous explosions and other major disruptions in space-time, which in turn ricochet off on their own courses, causing more explosions, et al. Imagine, however, what is happening at an atomic level. Atoms changing, breaking apart(?), forming molecules, etc, but importantly, the path of each individual atom is governed entirely by the forces and resistances surrounding it, and of course in large part by other atoms hitting it (or coming close and deterring them electromagnetically(?)). If you knew the position of every single atom in existence at any one point in time :wtf: , you could without error predict the movement of the entire universe, or the exact, and i mean EXACT path of a marble that has been hit by another marble, that was itself hit by a marble being flicked.... You could predict EXACTLY the movement of the leaves on a tree, an
Just one problem. With atomic and sub-atomic particles you can never know both the particles position and velocity at the same time. The more precisely you measure one, the less sure you can be of the other. This means you can never predict with any certianty where a particle will be or how fast and in what direction it will be traveling. You can only speak in terms of probablity. It is unkowable, and can only be given a probablity, just like a random event.
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1. I never claimed you COULD know these states, and 2. I've never been convinced the Heisenberg Uncertainty Principle was correct; it seems to be a limitation of physics technology. Who could say future developments couldn't allow such measurements? Recall that some time in the 1800s it was "proven" that heavier-than-air devices could never fly, and we all know how that turned out.
:doh: Sorry for late answer... @1: In a dream everything is possible - so live in your determined world ("Newton-Level"). @2. From a philosophical view you can always say you don't believe in something. But your reason... I know, cause of the simplified "meassure kick" explanations many people get that wrong. So I'd suggest you read some book about it, it's a really fascinating topic. I like to say that it seems that no way what you do, the universe keeps its secrets (a similar "uncertainty" is even in the Math! think about Gödel, unnatural numbers etc...)