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Golladzher
2010-Nov-11, 05:49 AM
I'd like to understand if a single radioactive nuclei truly decays randomly, or if any hypotheses have been posited that might lead to a theory that describes how a single nuclei decays. Though, I suspect such a theory would have sweeping consequences as it seems it would imply a purely deterministic universe.

Thanks all,

Strange
2010-Nov-11, 11:14 AM
Completely random, as far as I know. And I think you are right, discovery of an underlying cause would be a dramatic change to quantum theory.

tommac
2010-Nov-11, 12:28 PM
probibility

George
2010-Nov-11, 01:08 PM
probibility That sure seems probable. :) Is it likely a "disturbance in the force" (weak force) that triggers a decay?

Ronald Brak
2010-Nov-11, 01:18 PM
What triggers nuclei decay? Some nuclei can be rearranged into more stable forms and give off energy when they do. Vaccuum fluctuations can give nuclei the push they need to rearrange. These fluctuations are random. But I know very little on this topic. Wikipedia might be able to give you the dirt on this.

tommac
2010-Nov-11, 02:55 PM
That sure seems probable. :) Is it likely a "disturbance in the force" (weak force) that triggers a decay?

Can you show some proof of that? If that is the case then why would the probability be so constant?

grant hutchison
2010-Nov-11, 03:14 PM
Can you show some proof of that? If that is the case then why would the probability be so constant?Since George isn't on-line at present, I'll just point out that he was asking a question, not making a statement. So I doubt if "proof" will be forthcoming.

Grant Hutchison

tommac
2010-Nov-11, 05:02 PM
Please take a look at:

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

tommac
2010-Nov-11, 05:20 PM
You also may want to check out:
http://en.wikipedia.org/wiki/Many_worlds

tommac
2010-Nov-11, 05:21 PM
Is it likely a "disturbance in the force" (weak force) that triggers a decay?

No ... or at minimum that would lead to the follow up unansweable questions of what triggers the "disturbance in the force".

George
2010-Nov-11, 07:22 PM
Since George isn't on-line at present, I'll just point out that he was asking a question, not making a statement. So I doubt if "proof" will be forthcoming. Yes. "Poof" maybe. :) I am fairly sure that the weak force is responsible for decay, not that I understand it. I also vaguely recall trinitree convincing me (w/ at least one paper) that neutrinos are not responsible for triggering decay.

tommac
2010-Nov-11, 07:29 PM
Yes. "Poof" maybe. :) I am fairly sure that the weak force is responsible for decay, not that I understand it. I also vaguely recall trinitree convincing me (w/ at least one paper) that neutrinos are not responsible for triggering decay.

Nope. Maybe the quantum jitters.

George
2010-Nov-11, 07:53 PM
Nope.? Nope to the weak force responsible for decay?


Maybe the quantum jitters. I like that one. :) Perhaps when a given number of jitters pile on one another probalistically, then a decay takes place.

Strange
2010-Nov-11, 08:45 PM
Perhaps when a given number of jitters pile on one another probalistically, then a decay takes place.

Maybe you have found a way to combine chaos theory with quantum theory!

George
2010-Nov-11, 09:03 PM
Maybe you have found a way to combine chaos theory with quantum theory!Don't forget String "theory"! I've always liked "Good Vibrations". It must have been the surfing. ;)

Strange
2010-Nov-11, 09:43 PM
Turns out there is a field called quantum chaos but rather than trying to apply chaos theory to explain quantum mechanics, it looks at how classical chaos could emerge from quantum effects.

antoniseb
2010-Nov-11, 11:50 PM
Sorry for all the glib answers. The answer is not entirely trivial, but you can think of the nuclei as being complex systems with the many forces binding and repulsing the component parts. There are, at times, external contributions to the decay process, such as neutrino capture, or some other kind of particle capture for certain types of decay. For spontaneous fission, or alpha emission, it may be as simple as there just being an unlikely but possible set of motions (speaking in a Newtonian way about a quantum phenomenon) that result in the breaking apart of a borderline stable nucleus (like U235 for example). The chance of having this set of motions at any given time is like once in 13.2 billion years for Thorium, and quite a bit shorter to Beryllium-8

George
2010-Nov-12, 02:31 PM
Sorry for all the glib answers. The answer is not entirely trivial, but you can think of the nuclei as being complex systems with the many forces binding and repulsing the component parts. There are, at times, external contributions to the decay process, such as neutrino capture, or some other kind of particle capture for certain types of decay. For spontaneous fission, or alpha emission, it may be as simple as there just being an unlikely but possible set of motions (speaking in a Newtonian way about a quantum phenomenon) that result in the breaking apart of a borderline stable nucleus (like U235 for example). The chance of having this set of motions at any given time is like once in 13.2 billion years for Thorium, and quite a bit shorter to Beryllium-8 Is it that the "motions" are known and the probability of decay comes from calculations of these motions, or is it that the decay rate is known so the motion conditions are assumed from this?

Jeff Root
2010-Nov-12, 04:25 PM
Is it that the "motions" are known and the probability of decay comes
from calculations of these motions, or is it that the decay rate is known
so the motion conditions are assumed from this?
I don't know the answer, but I will bet you any amount of ice cream
that it is neither. I know that the motions aren't known (depending
somewhat on just what you mean by "motions" and by "known").
The decay rates are known, but I'm betting the ice cream that
knowing the the decay rate doesn't tell us anything about the
motions of the particles. It just tells us the probability of the
required conditions occurring.

I think the "conditions" simply amount to the particles being in
the same place at the same time-- in other words, colliding, The
particles are in random motion, so there is nothing to measure
that could serve as an indicator of when they will collide. Thus
the time is completely unpredictable.

-- Jeff, in Minneapolis

antoniseb
2010-Nov-12, 05:11 PM
Is it that the "motions" are known and the probability of decay comes from calculations of these motions, or is it that the decay rate is known so the motion conditions are assumed from this?

Don't try to get too precise with this hand-waving non-quantum explanation. There is evidence that heavy nuclei behave as though they have a shell model describing the placement of the nucleons in the nucleus (based on the spin of Pions that escape when the nucleus is struck with 142MeV gammas) so we have some crude view into the physical structure of the motions in the nucleus, but realistically, each proton and neutron are a triad of quarks held together by strong force all interacting in very complex ways. You can't write a Hamiltonian to describe it. All you can do is look at the fission or alpha decay rate and say, that must be it. As it happens, IIRC, that rate can depend on the ionization state of the nucleus to a small degree, so surrounding fields have a small impact. I expect that in a magnetar's surface field, the decay rates would change quite a bit, since the magnetic field would exceed cause the nuclei to be less spherical, and therefor more subject to having local charge exceed the weak force.

George
2010-Nov-12, 05:40 PM
I don't know the answer, but I will bet you any amount of ice cream
that it is neither. I know that the motions aren't known (depending
somewhat on just what you mean by "motions" and by "known").
The decay rates are known, but I'm betting the ice cream that
knowing the the decay rate doesn't tell us anything about the
motions of the particles. It just tells us the probability of the
required conditions occurring. I won't hold my breath for someone to take that bet. :)


I think the "conditions" simply amount to the particles being in
the same place at the same time-- in other words, colliding, The
particles are in random motion, so there is nothing to measure
that could serve as an indicator of when they will collide. Thus
the time is completely unpredictable. Is collision between other atoms or nuclei what you suspect triggers decay? That would be testable by comparing rates with particles in a vacuum.



As it happens, IIRC, that rate can depend on the ionization state of the nucleus to a small degree, so surrounding fields have a small impact. That's interesting. Anything in georgeeze when it involves quantum anything is appreciated. :)


I expect that in a magnetar's surface field, the decay rates would change quite a bit, since the magnetic field would exceed cause the nuclei to be less spherical, and therefor more subject to having local charge exceed the weak force.Perhaps other factors would also contribute to the rate given such extreme conditions, though we don't have normal radioactive material to work with.

Jeff Root
2010-Nov-12, 06:10 PM
I won't hold my breath for someone to take that bet. :)
Will you hold your spoon?



Is collision between other atoms or nuclei what you suspect triggers
decay? That would be testable by comparing rates with particles in
a vacuum.
No, collisions between quarks in a single nucleon, I think. It has been
years since I read about this. I have only the vaguest memory of it.
I know that individual quarks cannot be extracted from a nucleon.
As I'm sure you also know, any attempt to knock a quark out of a
nucleon adds so much energy to the assemblage of quarks that a new
mate for the freed quark is created from that energy, so that we end
up with a meson instead of a free quark... That fact may be relevant
somehow, but I'm not quite sure how...

-- Jeff, in Minneapolis

Grey
2010-Nov-12, 06:37 PM
As a side note, it's not just radioactive decay. Quantum mechanics always gives a probabilistic prediction for the behavior of any system, whether it's a radioactive isotope emitting an alpha particle, the decay of a single muon, a randomly polarized photon passing through a polarized filter, where an electron lands in a diffraction experiment, or anything else. We have no idea whether those processes are fundamentally random, or if there are underlying mechanisms that produce the apparently random behavior we see. It's entirely possible that we may not ever be able to know the answer to that.

tommac
2010-Nov-12, 07:27 PM
With respect ...
I dont know much about the quantum ( and would be argued by people on this board ... any ) physics but the one thing I know is you must be very careful making any Newtonian references or analogies when dealing with quantum physics. I believe Bohr often took exception to similar such wording. From what i understand the world of quantum physics lives in a world where possibilities are the reality rather than a manipulation about reality. Trying to make Newtonian references to such things can trivialize this major philosophical point.





Sorry for all the glib answers. The answer is not entirely trivial, but you can think of the nuclei as being complex systems with the many forces binding and repulsing the component parts. There are, at times, external contributions to the decay process, such as neutrino capture, or some other kind of particle capture for certain types of decay. For spontaneous fission, or alpha emission, it may be as simple as there just being an unlikely but possible set of motions (speaking in a Newtonian way about a quantum phenomenon) that result in the breaking apart of a borderline stable nucleus (like U235 for example). The chance of having this set of motions at any given time is like once in 13.2 billion years for Thorium, and quite a bit shorter to Beryllium-8

tommac
2010-Nov-12, 07:31 PM
In quantum physics probabilities are REAL ... the cat is both dead and alive. It is a totally different paradigm that is not compatible with newtonian physics.


I don't know the answer, but I will bet you any amount of ice cream
that it is neither. I know that the motions aren't known (depending
somewhat on just what you mean by "motions" and by "known").
The decay rates are known, but I'm betting the ice cream that
knowing the the decay rate doesn't tell us anything about the
motions of the particles. It just tells us the probability of the
required conditions occurring.

I think the "conditions" simply amount to the particles being in
the same place at the same time-- in other words, colliding, The
particles are in random motion, so there is nothing to measure
that could serve as an indicator of when they will collide. Thus
the time is completely unpredictable.

-- Jeff, in Minneapolis

tommac
2010-Nov-12, 07:38 PM
Whatever it is I would be willing to bet that it wouldnt make sense to anything we can observe.
One thing like Bells theorem about quantum entanglement ( instantaneous communication between quantum particles ) proves that no localized theory could be used to explain it.


As a side note, it's not just radioactive decay. Quantum mechanics always gives a probabilistic prediction for the behavior of any system, whether it's a radioactive isotope emitting an alpha particle, the decay of a single muon, a randomly polarized photon passing through a polarized filter, where an electron lands in a diffraction experiment, or anything else. We have no idea whether those processes are fundamentally random, or if there are underlying mechanisms that produce the apparently random behavior we see. It's entirely possible that we may not ever be able to know the answer to that.

tommac
2010-Nov-12, 08:06 PM
One source ...
http://bigthink.com/ideas/20525
There are many other similar linsk

my bolds ...

This theory offers a very different way to view the world they we live in—one where the simple laws of conventional physics simply don’t apply at all. Quantum theory is so eccentric and peculiar that even Einstein himself couldn’t wrap his head around it. The great physicist, Richard Feynman once stated that “It is impossible, absolutely impossible to explain it in any classical way”.

Some of what quantum theory predicts and states is almost like something out of science fiction. Matter can essentially be in an infinite number of places at any given time; it is possible that there are many worlds or a multiverse; things disappear and reappear somewhere else; you cannot simultaneously know the exact position and momentum of an object; and even quantum entanglement (Einstein referred to it as spooky action at a distance) where it’s possible for two quantum particles to link together effectively making them part of the same entity or entangled. Even if these particles are separated, a change in one is ultimately and instantly reflected in it’s counterpart. At the end of the day, the world of entanglement caused physicists like Einstein to both dislike the predictions and feel nothing more as if their were serious errors in the calculations. As Einstein once wrote: "I find the idea quite intolerable that an electron exposed to radiation should choose of its own free will, not only its moment to jump off, but also its direction. In that case, I would rather be a cobbler, or even an employee in a gaming house, than a physicist".

antoniseb
2010-Nov-12, 08:48 PM
With respect ... you must be very careful making any Newtonian references or analogies when dealing with quantum physics. ...
Are you saying I was not careful, or that you believe what I said (in its entirety) to be in error or not a useful way to think about it?

caveman1917
2010-Nov-12, 09:15 PM
Tommac i think you are focusing on that aspect in Antoniseb's explanation which is not the main gist of the answer. As far as i understand, what happens (recall the other thread on entropy) is that you get a possible set of states and a probability distribution over that set. Some of these states will give decay. What happens then just boils down to in essence taking a random walk over that set of states & probability distribution, and whenever you land upon a 'decay state' you get a decay.

But wether you want to think about those states themselves in classical terms or quantum terms is not all that pertinent to the underlying behaviour concerning decay. It will only start to matter when you're actually trying to calculate the states and which ones are 'decay states'.

tommac
2010-Nov-12, 09:23 PM
While I partially agree ... why is there the need for the classic terms. It is only against using the classic terms that is my protest. The probability itself does a better job in explaining what is "really" going on.


Tommac i think you are focusing on that aspect in Antoniseb's explanation which is not the main gist of the answer. As far as i understand, what happens (recall the other thread on entropy) is that you get a possible set of states and a probability distribution over that set. Some of these states will give decay. What happens then just boils down to in essence taking a random walk over that set of states & probability distribution, and whenever you land upon a 'decay state' you get a decay.

But wether you want to think about those states themselves in classical terms or quantum terms is not all that pertinent to the underlying behaviour concerning decay. It will only start to matter when you're actually trying to calculate the states and which ones are 'decay states'.

tommac
2010-Nov-12, 09:25 PM
Are you saying I was not careful, or that you believe what I said (in its entirety) to be in error or not a useful way to think about it?

the latter. Specifically this part:


it may be as simple as there just being an unlikely but possible set of motions (speaking in a Newtonian way about a quantum phenomenon) that result in the breaking apart of a borderline stable nucleus (like U235 for example).

EDIT: however as usual I could be totally wrong ... but if I am I would like to ask what you base this statement on.

antoniseb
2010-Nov-13, 02:23 AM
... however as usual I could be totally wrong ... but if I am I would like to ask what you base this statement on.
I make this statement actually knowing quite a bit about the inner workings of the nucleus, but preferring in this forum to use terminology that helps the layman better visualize what's happening than if I laid out the quantum chromodynamic details.

tommac
2010-Nov-13, 02:59 AM
I make this statement actually knowing quite a bit about the inner workings of the nucleus, but preferring in this forum to use terminology that helps the layman better visualize what's happening than if I laid out the quantum chromodynamic details.

I wanted to make sure that I used the words respectfully in my protest. But I am not sure that trying to make the newtonian analogy helps or hurts the situation. It seems to me to cause more harm to a layman ( SUch as myself ) to have such an analogy presented in the name of simplification than the benefit that the analogy provides.

I in no way meant the protest to question your understanding on the matter.

Jeff Root
2010-Nov-13, 02:15 PM
Tom,

Exactly what analogy are you referring to? I don't consider what
antoniseb said about motions (of quarks I presume) to be an analogy.

-- Jeff, in Minneapolis

caveman1917
2010-Nov-13, 04:26 PM
I had understood the analogy as somewhat like thinking of the nucleus as the solar system with the planets being alpha particles which are normally bound together. But you can have a set of possible motions which will give for example Neptune such velocity that it exceeds solar escape velocity and is thus ejected from the system, which would by the analogy correspond to alpha decay.

antoniseb
2010-Nov-13, 04:45 PM
I had understood the analogy as somewhat like thinking of the nucleus as the solar system with the planets being alpha particles which are normally bound together. But you can have a set of possible motions which will give for example Neptune such velocity that it exceeds solar escape velocity and is thus ejected from the system, which would by the analogy correspond to alpha decay.

Maybe more like a small globular cluster... except that in the nucleus includes significant repulsive forces, AND the attractive forces don't follow the inverse square law AND includes some doubt as to the actual position of any particle inside it, AND that sometimes the motions and quantum shell-filling result in a football shaped nucleus suddenly becoming a little more dumbbell shaped, resulting in fission.

tommac
2010-Nov-13, 05:33 PM
Can you please define motion? Or clarify the definition of motion that is being used?

Tom,

Exactly what analogy are you referring to? I don't consider what
antoniseb said about motions (of quarks I presume) to be an analogy.

-- Jeff, in Minneapolis

tommac
2010-Nov-13, 05:36 PM
I had understood the analogy as somewhat like thinking of the nucleus as the solar system with the planets being alpha particles which are normally bound together. But you can have a set of possible motions which will give for example Neptune such velocity that it exceeds solar escape velocity and is thus ejected from the system, which would by the analogy correspond to alpha decay.

Yes ... and this at least from me is what my protest is about. While it may paint a nice picture it really has little to do with what is happening. What is happening has much less to do with Newtonian motion than it does with probabilities being real ( and possibly fully descriptive) .

tommac
2010-Nov-13, 05:37 PM
Maybe more like a small globular cluster... except that in the nucleus includes significant repulsive forces, AND the attractive forces don't follow the inverse square law AND includes some doubt as to the actual position of any particle inside it, AND that sometimes the motions and quantum shell-filling result in a football shaped nucleus suddenly becoming a little more dumbbell shaped, resulting in fission.

And time and space probably doesnt exist as we know it ... and relativity probably doesnt exist and particles can be in multiple places at the same time and ....

caveman1917
2010-Nov-13, 06:09 PM
Maybe more like a small globular cluster... except that in the nucleus includes significant repulsive forces, AND the attractive forces don't follow the inverse square law AND includes some doubt as to the actual position of any particle inside it, AND that sometimes the motions and quantum shell-filling result in a football shaped nucleus suddenly becoming a little more dumbbell shaped, resulting in fission.

All very true. While the various forces can be easily considered in a newtonian way, i don't know how you would incorporate something as inherently quantum as the uncertainty principle in a newtonian model.

grant hutchison
2010-Nov-13, 06:11 PM
And time and space probably doesnt exist as we know it ... and relativity probably doesnt exist and particles can be in multiple places at the same time and ....And so no explanation is possible? But then you disappear in nihilistic solipsism, and you can't do any science.
When we do science, we tell coherent stories that describe the maths of our theories, and those stories turn out to be like the story antoniseb gave you. We need to bear in mind their limitations, for sure, but the limitations don't render the stories invalid.

Grant Hutchison

caveman1917
2010-Nov-13, 06:12 PM
and relativity probably doesnt exist

Doesn't QCD fully incorporate SR? At least QED does, so i wouldn't expect chromodynamics to be different in this aspect, but i may be wrong of course.

tommac
2010-Nov-13, 06:24 PM
Doesn't QCD fully incorporate SR? At least QED does, so i wouldn't expect chromodynamics to be different in this aspect, but i may be wrong of course.

How is quantum entanglement explained using SR?

korjik
2010-Nov-13, 06:28 PM
How is quantum entanglement explained using SR?

It isnt. It is explained using Quantum Mechanics. Quantum Mechanics is fully compatable with Special Relativity. That is what Caveman was talking about.

korjik
2010-Nov-13, 06:30 PM
And time and space probably doesnt exist as we know it ... and relativity probably doesnt exist and particles can be in multiple places at the same time and ....

Special relativity works fine with Quantum Mechanics. General Relativity dosent.

And particles dont exist at multiple places at the same time.
And space and time can be defined perfectly fine.

You really ought to learn the physics before you try to apply it.

antoniseb
2010-Nov-13, 07:43 PM
Doesn't QCD fully incorporate SR? At least QED does, so i wouldn't expect chromodynamics to be different in this aspect, but i may be wrong of course.
Relativistic QCD includes SR, but inside the nucleus, the nucleons and pions (and within these the quarks and gluons) are not working at energies where SR really changes the solutions. RQCD is important when analyzing LHC results.

tommac
2010-Nov-13, 09:52 PM
And particles dont exist at multiple places at the same time.


I guess it depends on how you define a particle. But look at hte double slit experiment. Also unless you observe a particle it exists in all states.

Hornblower
2010-Nov-13, 10:11 PM
I have no quarrel with antoniseb's use of a Newtonian analogy such as a globular cluster. It provides novices with a more visualizable mental picture in which random fluctuations occasionally result in the ejection of a component of what would be a metastable system in the absence of those fluctuations.

Jeff Root
2010-Nov-13, 10:43 PM
Tom,

Exactly what analogy are you referring to? I don't consider what
antoniseb said about motions (of quarks I presume) to be an analogy.
Can you please define motion? Or clarify the definition of motion that is being used?
That's a good question, especially considering I said to George,
"depending somewhat on just what you mean by "motions" and
by "known". But in that case George is the one who used the term,
and in this case antoniseb is the one who used it, so they should
be the people to define what they mean.

It might possibly help if you can explain what difficulty you have
conceptualizing motion of quarks, or what you hope a definition
might accomplish. I, myself, intuitively understand motion of
quarks as like any other motion, and don't worry about it at all.
A thing is one place, then it is another place, and the thing's
motion is that change of location.

I do not consider motion of quarks to be an analogy, because I do
not make an analogy between quarks and anything else. I do not
consider their motion to be analogous to the motions of planets
in a solar system or stars in a globular cluster. Quarks have their
own properties that are different from the properties of planets
and stars. They follow their own rules.

I would say that if it were possible to know the positions and
velocities of the quarks in a nucleon at a given instant, then one
might be able to say something about what the nucleon would be
doing in the next instant. But it is never possible to know the
positions and velocities of the quarks in a nucleon. So their
behavior can only be predicted statistically. But that doesn't
mean the quarks aren't really buzzing around inside the nucleon.
We can't see them, and will never be able to see them, we can't
say anything at all about where they are or what direction they
are moving at a given instant, and never will, but quarks have
properties that are particle-like, so they can be described as
particles, and that is how I conceptualize them.

I don't accept the notion that a particle can be in different places
simultaneously. That is a reality of the statistics, not of the
particle. You can't know where the particle is until it is detected,
and statistically, until it is detected, it is everywhere. But that
is just statistics. The same statistics could be applied to people.
You don't know where a person is until he is detected, so until
he is detected, he could statistically be everywhere at once.
The only difference is that with people, you could watch them
constantly, while fundamental particles cannot be watched.
Just don't watch the people, pretend that you can't watch them,
and you can have a Copenhagen interpretation of people being
everywhere at once.

-- Jeff, in Minneapolis

tommac
2010-Nov-14, 03:40 AM
It might possibly help if you can explain what difficulty you have
conceptualizing motion of quarks, or what you hope a definition
might accomplish. I, myself, intuitively understand motion of
quarks as like any other motion, and don't worry about it at all.
A thing is one place, then it is another place, and the thing's
motion is that change of location.

Well it is just one of the issues I have .... but when you say it is in one place then it is in another place .... which places are you referring to?
I would think that some quantum physicists might argue that the quark occupies all of the places where it could possibly be simultaneously.

Also as the quark is also a wave then I just dont get how any useful newtonian analogy could be used describing them or their "Motion".

Say we had a pattern of polka dots on a computer screen. After a few minutes the same dots appearsed in another different pattern. COuld we say that was motion?

Here is an article written about hte "Motion" of quarks:
http://www.sciencedaily.com/releases/2010/09/100927105029.htm

Over several years it became increasingly clear that the way in which the left-handed and right-handed quarks come together can be described using a massive quantities of random numbers. This doesnt sound in the least Newtonian or even as movement.

They use the words swing and dance .... which I hope werent meant to be taken literally but to which I hsort of have the same objection to.

tommac
2010-Nov-14, 04:09 AM
I don't accept the notion that a particle can be in different places
simultaneously.

Do you accept the notion that entangled particles can have non-local instantaneous communication?



That is a reality of the statistics, not of the
particle.

That is the point .... the statistics are the particle. The statistics are real. The same way the dog is both alive and dead.


From: http://www.sciencenews.org/view/feature/id/65056/title/Clash_of_the_Quantum_Titans

At the heart of these disputes is the very nature of reality itself, and whether quantum physics is the last word on how to describe it. Zeilinger, of the University of Vienna, advocates the standard quantum view of reality’s fuzziness. “It turns out that the notion of a reality ‘out there’ existing prior to our observation … is not correct in all situations,” he points out.

Yet some physicists cling to the prejudice that cause-and-effect determinism will someday be returned to its privileged status, and physics will restore objectivity to reality.

“I basically understand why people have this position,” Zeilinger responds. “But the evidence is overwhelming that this approach would not succeed.”

tommac
2010-Nov-14, 04:16 AM
I have no quarrel with antoniseb's use of a Newtonian analogy such as a globular cluster. It provides novices with a more visualizable mental picture in which random fluctuations occasionally result in the ejection of a component of what would be a metastable system in the absence of those fluctuations.

But is there any cause and effect? Or is it just that a random percentage of the time a state happens where a photon is emmited. From what I have read there is no cause and effect relationship. So why try to explain something, that is fairly simple in terms of probabiliies, in newtonian terms so as to simplify it for the layman like myself? Why not just leave it as saying if it is probable then it just is.

tommac
2010-Nov-14, 04:21 AM
I have no quarrel with antoniseb's use of a Newtonian analogy such as a globular cluster. It provides novices with a more visualizable mental picture in which random fluctuations occasionally result in the ejection of a component of what would be a metastable system in the absence of those fluctuations.

To go back to the OQ :


What triggers radioactive nuclei decay?

Wouldnt it just be easiest to say that the radioactive nuclei decay is non-deterministic? and that the reason it happens is because there is a probability of it happening.

Could anything more be proven?

macaw
2010-Nov-14, 04:45 AM
I'd like to understand if a single radioactive nuclei truly decays randomly, or if any hypotheses have been posited that might lead to a theory that describes how a single nuclei decays. Though, I suspect such a theory would have sweeping consequences as it seems it would imply a purely deterministic universe.

Thanks all,

The process is random. The nuclei of radioactive materials exhibit an unstable equilibrium between the repulsive electrostatic force (which decays with 1/r^2) and the stronger, attractive nuclear force (which decays much faster than 1/r^2 but dominates the electrostatic force for small distances). The nuclei of radioactive materials cram together a very large number of protons and this increases their size, thus increasing the probability for the electrostatic force to overcome the nuclear force. If such a nucleus is "tapped" lightly by the arrival of a slow neutron (that acts as a catalyst), the nucleus breaks down freeing a large amount of energy in the process. The arrival of "catalysts" is random, thus the whole process is random.

One might want to ask two corollary questions:

1. What keeps the atoms together? Why don't the electrons "fall" into the nucleus ?
Answer : Heisenberg uncertainty principle says that if the electrons were confined in an ever smaller space their momenta would be ever increasing, balancing the attempt to "collapse" them into the nucleus.

2. Why don't the electrons or the protons "fly apart" under the influence of their own charge? Is there a sort of "nuclear force" that balances the electrostatic force as in the case of atoms above?
Answer: no one knows. This is an open question.

Jeff Root
2010-Nov-14, 05:15 AM
Well it is just one of the issues I have .... but when you say it is in one
place then it is in another place .... which places are you referring to?
I would think that some quantum physicists might argue that the quark
occupies all of the places where it could possibly be simultaneously.

Also as the quark is also a wave then I just dont get how any useful
newtonian analogy could be used describing them or their "Motion".
A quark or other fundamental particle is not a wave. It is described
by a wave function, and behaves according to the mathematics
which describes particular types of waves.



Say we had a pattern of polka dots on a computer screen. After a
few minutes the same dots appearsed in another different pattern.
Could we say that was motion?
Excellent confounding example. I can only assert that individual
particles are distinct entities, and maintain a continuous existence
and separate identity from other particles, even if the particles
are completely identical to each other in every way. If you had
a dozen bearing balls that were completely indistinguishable, I
think you would not say that they were exchanging identities with
one another. Each bearing ball would be in a different location at
any given time. The difference between bearing balls and quarks
is that you could keep track of the individual bearing balls if you
wanted to, but you couldn't keep track of the quarks. The fact
that you can't keep track of something, even in principle, doesn't
mean that the thing isn't in any particular place. You just have no
way of knowing what that place is.

-- Jeff, in Minneapolis

Jeff Root
2010-Nov-14, 05:24 AM
Do you accept the notion that entangled particles can have non-local
instantaneous communication?
No.

I accept that they are entangled, though.



.... the statistics are the particle. The statistics are real. The same
way the dog is both alive and dead.
The statistics are not the particle. The statistics describe the particle.
The statistics accurately describe the dog as both alive and dead, but
the dog is not both alive and dead. The dog is either alive or dead,
but you don't know which. Statistically it is both. A dog is a dog, not
a statistic.

The statistics are real, and they do a great job of describing the
behavior of various things. But the statistics are not the things
whose behavior they describe.

-- Jeff, in Minneapolis

tommac
2010-Nov-14, 10:44 PM
You just have no
way of knowing what that place is.

How are you defining place? Centainly nothing like a newtonian place!
I am by no way any expert but it would see m that space and time as we know it breaks down at the quantum level
If space and time are not newtonian ... then any newtonian analogies would be like explaining what the inside of a black hole looks like.

Jeff Root
2010-Nov-15, 06:27 AM
I'm not defining "place" because the concept doesn't seem to
me to require definition. I can understand that it would seem
to others to require definition. To me, it is such a basic concept
that it isn't possible for me to define it.

If I say that we have no way of knowing what place a thing is in,
perhaps you will want to simply interpret that as meaning that
I *am* using a newtonian definition of place. Although I can't
imagine any definition that *would* allow us to know the place.

I have no reason to think that space and time "break down"
at small scales. I have plenty of reason to think that there are
limits to how small any space or time measurement can be,
but that does not imply that space and time somehow stop
being space and time.

I do not consider application of the ideas "space" and "time" to
very small scales to be analogies.

-- Jeff, in Minneapolis

tommac
2010-Nov-15, 02:51 PM
Although I can't
imagine any definition that *would* allow us to know the place.


This is the point. It is not the technology that is not yet up to par but that it just cant be done. We will never know the place.

Why are you so against space and time breaking down on very small scales?
Can you explain the double slit experiment using anything in the macro world?
Can you explain quantum entanglement using anything in the macro world?

Also even if it didnt break down ... does it really matter if we could never measure anything? Is there a difference between a true break down or a break down in the sense that we cant prove otherwise?

Is there a difference between a world in which probability is the reality vs a world where nothing can be observed other than probabilities no matter what you do.

Hornblower
2010-Nov-15, 09:07 PM
I continue to concur with antoniseb. Of course we cannot use a Newtonian analysis to study the actions in an atomic nucleus, but the same sort of entry level novice's mental picture makes sense to me. In a globular cluster we have chaotic gravitational interactions that once in a while gang up on a star and eject it from the cluster, while causing other stars to settle into lower energy states in the center. I am imagining the possibility that random quantum mechanical interactions in a nucleus are occasionally ganging up on an alpha particle and ejecting it. In each case the impetus was redistribution of energy that was inherent in each system. Very different mathematical details, but otherwise a good analogy as I see it.

Ara Pacis
2010-Nov-15, 09:37 PM
Can we use the bag model of quark confinement to explain it? Are the bags stretched out and knotted up and somehow happen to snap back when fission occurs? Or is there a soup of quarks mixing around inside the nucleus that only get together when it's time to leave the party?

Hlafordlaes
2010-Nov-15, 10:03 PM
And so no explanation is possible? But then you disappear in nihilistic solipsism, and you can't do any science.
When we do science, we tell coherent stories that describe the maths of our theories, and those stories turn out to be like the story antoniseb gave you. We need to bear in mind their limitations, for sure, but the limitations don't render the stories invalid.

Grant Hutchison

It's this kind of thread and its pithy BAUTian responses that make this my place to hear stories.

If BAUT were an aftershave, I'd slap it on every morning.

Jeff Root
2010-Nov-16, 02:01 PM
Why are you so against space and time breaking down on very
small scales?
Because I have no reason to think that they "break down".

-- Jeff, in Minneapolis

tommac
2010-Nov-17, 03:27 PM
Because I have no reason to think that they "break down".

-- Jeff, in Minneapolis

It breaks down because we cant observe them. Space and Time only make sense in an observational sense. If you want to look at this in a pure mathmatical sense then it breaks down and becomes a landscape of probability rather than the determanistic newtonian/einsteinian world in which we can observe.

May be a bit philosopical but space and time may be biased by the way our brains are configured. It seems that our brains work as holograms. Vision, Memory, hearing all operate holographically. It seems at least to the holographic model believers that the 3d + 1 t world that we percieve can really just be a holograph and that it is our holographly prejudiced brain forcing these dimentions on us.

So what really is space and time? Do they really exist at the quantum level?

Hornblower
2010-Nov-17, 05:33 PM
It breaks down because we cant observe them. Space and Time only make sense in an observational sense. If you want to look at this in a pure mathmatical sense then it breaks down and becomes a landscape of probability rather than the determanistic newtonian/einsteinian world in which we can observe.

May be a bit philosopical but space and time may be biased by the way our brains are configured. It seems that our brains work as holograms. Vision, Memory, hearing all operate holographically. It seems at least to the holographic model believers that the 3d + 1 t world that we percieve can really just be a holograph and that it is our holographly prejudiced brain forcing these dimentions on us.

So what really is space and time? Do they really exist at the quantum level?What is your definition, in appropriate technical and mathematical detail, of a hologram?

tommac
2010-Nov-18, 09:58 PM
What is your definition, in appropriate technical and mathematical detail, of a hologram?

I personally dont have a definition as it is not my theory. But according to the wikipedia and basically the definition that I am using although it is not that clear to me in a mathmatical sense:


The holographic principle is a property of quantum gravity and string theories which states that the description of a volume of space can be thought of as encoded on a boundary to the region—preferably a light-like boundary like a gravitational horizon. First recognized by Charles Thorn[1] and later proposed by Gerardus 't Hooft, it was given a precise string-theory interpretation by Leonard Susskind.

In a larger and more speculative sense, the theory suggests that the entire universe can be seen as a two-dimensional information structure "painted" on the cosmological horizon, such that the three dimensions we observe are only an effective description at macroscopic scales and at low energies. Cosmological holography has not been made mathematically precise, partly because the cosmological horizon has a finite area and grows with time.[2][3]

From my understanding holograms work in encoding all of the information in every part. If you have a hologram and cut it in 1/4s you will not lose any of the information but rather have 4 copies of the information. Our brains seem to do something similar. You can remove some of the brain without any memory loss.

Hearing and vision allow us to pinpoint things in 3 d by interpreting sound hitting our ears or light hitting our eyes. Even someone who has one eye can see in 3d. The idea is that our brains may influence our mathmatics about the universe by biasing it to look at everything in 3 dimensions. What if the world was 2d and just being interpretted as 3d. It would seem that the fuzzyness on the planck scale at least would fall into that. And the event horizon of the black hole would certainly shows some holographic properties.

grant hutchison
2010-Nov-18, 10:36 PM
From my understanding holograms work in encoding all of the information in every part. If you have a hologram and cut it in 1/4s you will not lose any of the information but rather have 4 copies of the information. Our brains seem to do something similar. You can remove some of the brain without any memory loss.Because some parts of the brain don't store memories.
The "holographic memory" idea stemmed from Lashley's work with maze-running rats in the 40s: the rats could still run the mazes after various bits of cortex had been removed, although there was a deterioration in function proportional to the size of the missing cortical chunk. But we now know that navigational memory resides primarily in the hippocampus, so little or no navigational memory was removed from these rats: Lashley was just watching brain-damaged rats with intact navigational memories. The dominant model nowadays is that specific memories reside in specific modifiable neuronal circuits: lose that bit of brain, lose that bit of memory.
So "holographic memory" is a rather fringe idea, often tied up with quantum mysticism. You haven't been reading Pribram, have you?

Grant Hutchison

tommac
2010-Nov-19, 05:27 AM
I was reading something maybe pribram ... and also Susskind ...


Because some parts of the brain don't store memories.
The "holographic memory" idea stemmed from Lashley's work with maze-running rats in the 40s: the rats could still run the mazes after various bits of cortex had been removed, although there was a deterioration in function proportional to the size of the missing cortical chunk. But we now know that navigational memory resides primarily in the hippocampus, so little or no navigational memory was removed from these rats: Lashley was just watching brain-damaged rats with intact navigational memories. The dominant model nowadays is that specific memories reside in specific modifiable neuronal circuits: lose that bit of brain, lose that bit of memory.
So "holographic memory" is a rather fringe idea, often tied up with quantum mysticism. You haven't been reading Pribram, have you?

Grant Hutchison

grant hutchison
2010-Nov-19, 12:34 PM
I was reading something maybe pribram ... and also Susskind ...From what I've read of Susskind, speculations on neurobiology don't seem his sort of thing.
Since you now seem to have become interested in Quantum Mechanics, you should be cautiously aware that it has a mystical fringe, which is strongly represented in non-technical books and internet sites. QM has many different interpretations, and it's important to distinguish core QM from those various interpretive overlays, especially the ones that invoke dubious neurobiology.

Grant Hutchison

tommac
2010-Nov-19, 04:21 PM
Yes I definitely noticed that when I was reading that article about the holographic principle. They went on to state that maybe seemingly unrelated events can be linked via the projected dimensions at that point I devalued the article.

But ... much of what I am referring to above is from what I read from Bohr. It seemed that he in particular was a stickler for wording because the quantum world was so different from the newtonian world.

Personally I feel that physicists are trying to somehow combine these two worlds into one ... and while I agree that they are related I am not sure of the need to project the macro version of space time and movement to the quantum world.

I took my kids to disney last year and they had lego land or something like that there. When you approach it you see these statues of dinosaurs they look perfectly smooth. but when you get close up you see that there in fact are no curves. Everything is made from legos just that at a distance the resolution makes it looks like curves. I see the quantum world as being just that. It is in the quantum world that space-time is created but I dont think it really exists on the quantum level ... at least it is nothing like we experience in the macro world. I dont have a problem with there being two sets or laws and two sets of paradigms to describe the lego vs the statue. Not sure if that is correct or not but that is my novice understanding.

From what i understand Bohr insisted that when referring to almost anything in the quantum world you must state it in terms of observations and not make underlying assumptions and analogies as to why something is happening. I was looking for some exact quotes but could not quickly find any. Thoughts?


From what I've read of Susskind, speculations on neurobiology don't seem his sort of thing.
Since you now seem to have become interested in Quantum Mechanics, you should be cautiously aware that it has a mystical fringe, which is strongly represented in non-technical books and internet sites. QM has many different interpretations, and it's important to distinguish core QM from those various interpretive overlays, especially the ones that invoke dubious neurobiology.

Grant Hutchison

antoniseb
2010-Nov-19, 05:00 PM
... Thoughts?
I'm thinking you are waaaay off topic, and should perhaps bring this up in a new thread in off-topic babbling.