Unexpected Shape of Lead-208 Nucleus May Force Scientists to Reevaluate Atomic Nuclei Models (phys.org) 51
"An international research collaboration led by the University of Surrey's Nuclear Physics Group has overturned the long-standing belief that the atomic nucleus of lead-208 is perfectly spherical," reports Phys.org.
They add that the discovery "challenges fundamental assumptions about nuclear structure and has far-reaching implications for our understanding of how the heaviest elements are formed in the universe..." [A] new study published in Physical Review Letters used a high-precision experimental probe to examine its shape and found that rather than being perfectly spherical, the nucleus of lead-208 is slightly elongated, resembling a rugby ball (prolate spheroid)... Using the state-of-the-art GRETINA gamma-ray spectrometer at Argonne National Laboratory in Illinois, U.S., scientists bombarded lead atoms with high-speed particle beams accelerated to 10% of the speed of light — equivalent to circling the Earth every second. The interactions created unique gamma-ray fingerprints of the properties of excited quantum states in lead-208 nuclei — in other words, the nuclei were energized — which, in turn, were used to determine its shape.
Theoretical physicists, including those at the Surrey Nuclear Theory Group, are now re-examining the models used to describe atomic nuclei, as the experiments suggest that nuclear structure is far more complex than previously thought.
They add that the discovery "challenges fundamental assumptions about nuclear structure and has far-reaching implications for our understanding of how the heaviest elements are formed in the universe..." [A] new study published in Physical Review Letters used a high-precision experimental probe to examine its shape and found that rather than being perfectly spherical, the nucleus of lead-208 is slightly elongated, resembling a rugby ball (prolate spheroid)... Using the state-of-the-art GRETINA gamma-ray spectrometer at Argonne National Laboratory in Illinois, U.S., scientists bombarded lead atoms with high-speed particle beams accelerated to 10% of the speed of light — equivalent to circling the Earth every second. The interactions created unique gamma-ray fingerprints of the properties of excited quantum states in lead-208 nuclei — in other words, the nuclei were energized — which, in turn, were used to determine its shape.
Theoretical physicists, including those at the Surrey Nuclear Theory Group, are now re-examining the models used to describe atomic nuclei, as the experiments suggest that nuclear structure is far more complex than previously thought.
resembling a rugby ball? (Score:3, Funny)
So IOW, the soccer rules are out the window and you're allowed to touch the nucleus with your hands?
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Re: resembling a rugby ball? (Score:2)
Worse - imagine kicking a nucleus ball - thatâ(TM)s far more dense. Like - as dense as a neutron star, so youâ(TM)re talking in the region of 8*10^16kg for a rugby ball
Re:resembling a rugby ball? (Score:5, Funny)
So IOW, the soccer rules are out the window and you're allowed to touch the nucleus with your hands?
The real question is, can you lick it [memeguy.com]?
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3 licks to the center.
Nuclear models are semi-empiric (Score:5, Informative)
That is, they diverge from one another severely where data isn't available, and converge, despite their vastly different assumptions, where data is available.
It isn't news they are "wrong", we know very well why, it is just that the real shit is so complicated, that it simply does not compute.
The imperfect models will be "refined" to reflect the new data until such time as our "AGI" overlords come up with the real model.
The one that we won't understand anyway.
Or, alternatively, we'll get it, as we've gotten most stuff so far and still be cool.
Re:Nuclear models are semi-empiric (Score:5, Informative)
Bismuth was wrong until we incorporated the relativistic effects of the outer electrons.
This might actually be a great find if it can help rule in/out certain gravity models.
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The relativistic effects on electron orbitals is limited to the increase of apparent electron mass with electron speed. It has nothing to do with gravity.
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The only reason we have models is because we haven't solved Schrodinger's Equation for elements other than hydrogen.
The orbital shells you see drawn out are the orbital probabilities for hydrogen. But once you add two electrons the picture changes. We haven't been able to calculate them, but we can image them, so we know that the hydrogen molecule (H2) looks a lot more like a hot dog with bun.
But the math is very hard and I don't think there's actually a calculation of the hydrogen molecule itself.
Everythin
What does "perfectly" mean here? Clearly not that. (Score:5, Insightful)
How can anything made out of discrete anything be "perfectly" any shape? If you zoom in far enough on anything, it turns out to be made out of smaller parts, and it's lumpy. And the parts are moving.
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Yes, the solution is a perfect sphere, and the actual measurements confirm that within the margin of error. Unlike your imaginary cow.
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Didn't the epicyclists take measurements that supported their circular-orbit theory within margins of error too?
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Didn't the epicyclists take measurements that supported their circular-orbit theory within margins of error too?
If epicycles aren’t working, you’re not using enough epicycles.
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No. They were adding epicycles because errors accumulated over the error margins continuously and for no valid reason within the theoretical framework. With the electron orbits there is no such thing. Not only do you get an exact solution, which predicts the spectral lines perfectly, it also explains the empirical formulas derived from the observations.
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Didn't they even have a mechanical device that predicted orbits accurately enough for their purposes?
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Yes. But over a decade you needed to buy a new one with more epicycles.
Basically, the epicycles are a curve fit. You can fit a curve perfectly to any data set using one of several methods, but it doesn't mean the curve by itself tells you anything about the phenomenon that has generated the data.
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As far as I know no one has ever discovered any internal structure to the electron. You can pump it full of so much energy that things start boiling off or it is destroyed and turns into something else, but no one has been able to identify any components yet. It is like an ideal point particle - a fermion with spin, mass, and a charge, but no internal structure and only distorted from spherical symmetry by something like an applied electric field.
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True, no internal structure, but false, point particle. An electron is only a point particle if measured, otherwise it is an arbitrarily complex 3D probability wave function.
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Yes, that goes without saying. Although the idea that any wavefunction that is not a Bayesian figment of your imagination actually collapses is preposterous. Pretty sure the world still exists when no one is there to look at it. David Bohm had a better idea.
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Everyone has the right to favor the interpretation that seems most intuitive to them, but this does not change the fact that Bohm's model (or the any of the other physical interpretations of quantum mechanics) are not superior to Copenhagen interpretation in any testable way.
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Sure. Some people prefer to believe that the world is not real until they look at it, Or is purely a figment of their own imagination. And that other people aren't real either. It is not look you can prove anyone else other than you is conscious or actually exists at all. The Bohr interpretation is brain dead stupid like that. True science deals in reality not delusions, compelled ignorance, nor wishful thinking. Philosophical mumbo jumbo should be saved for philosophers who are so skeptical they are
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But your rant only adds philosophical mumbo jumbo to the steaming pile.
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You should try reading the Bohr interpretation sometime. Either that or we could get into a real discussion about the level of unreality that has been associated with quantum mechanics since the 1920s. As Einstein once said, "God does not play dice with the universe". Science is generally speaking about what is real not entities that exist only in the mind of the observer. A typical example is Schroedinger's cat. You take a cat and place it in a closed box. Inside the box there is an atom that if it d
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Your multiple observer argument is easily addressed, even at my level of naivety with respect to this deep subject. Only one observer collapses the wave state and subsequent observers observe the collapsed state. Are you sure you are equipped to argue these points? You certainly seem to think you are, but can you do the math?
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Of course. But action at a distance throughout the entire universe is like the most physically unrealistic thing a scientist has ever contemplated. Similar to the idea that you have a finite probability of materializing on a planet orbiting Alpha Centauri in the next five minutes and never making it back.
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Pardon me, but time running at different speeds in different parts of the universe is way more physically unrealistic to me that spooky action at a distance. Nonetheless this is experimentally verified, as is spooky action at a distance, or non-local correlation as we could say more precisely.
Hey, maybe it's time to put the buggy whip away and get up to speed on modern physics. It's not like it isn't highly predictive and yielding stunning new results verging on magic every day.
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It is well known that quantum mechanics isn't remotely compatible with general or special relativity so I don't know how you see that the questionable proposition that time runs at different speeds in different parts of the universe (except from the perspective of a given observer for various reasons) comes into this. Quantum electrodynamics does produce results that are accurate to twelve decimal places which is astounding, but Schroedinger's equation is deterministic and does not require the Bohr interpr
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There are superior, deterministic alternatives like the Bohm formulation of quantum mechanics that are more than adequate.
Lovely. Except that you can't prove that Bohm interpretation is superior to any of the other interpretations except by bluster. You claim that failure to settle on your favorite interpretation holds back progress, while in fact QM continues to make astounding progress both theoretically and practically without any explanation of why it works. If you are going to continue shouting at the
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Okay we are just going to have to disagree here. Not sure why you think that ad hominems is the way to win an argument but it doesn't matter. Real experts will continue to debate this issue and probably for years to come. I need to focus on other things, like my walls that need repairing in the basement and other places. I wish I had time to discuss this in more detail but I don't. It is a worthwhile thing to discuss though.
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What is the ad hominem part according to you, calling your non-technical bluster bluster, or wondering about your technical qualifications?
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Give it up. You are just wasting your time.
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You aren't?
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Every proton has exactly the same mass to whatever precision we manage to measure. There is indeed something perfect about that, in spite of the fact that the internal structure of the proton is incredibly complex. That is the thing... down at that level things actually do become perfect. Quantum operators for example. And, as far as we can tell, perfectly random as well, though again in the case of the proton, all that perfect randomness does add up to something perfectly non-random, that is, the proton ma
Magic is an illusion, double magic doubly so. (Score:4, Informative)
Hm, the headline says that this nucleus is slightly less spherical than expected. I wonder how non-spherical we're talking about, like as a ratio of the "equatorial" diameter to the "polar". The summary doesn't say. Maybe I can piece it together from the article itself. How hard can it be?
"Lead-208 is the heaviest known doubly magic nucleus and its structure is therefore of special interest. Despite this magicity,"
Aaaand I'm out.
Re:Magic is an illusion, double magic doubly so. (Score:5, Informative)
"Lead-208 is the heaviest known doubly magic nucleus and its structure is therefore of special interest. Despite this magicity,"
There are magic numbers [wikipedia.org] of neutrons or protons in the nucleus, which are especially stable: 2, 8, 20, 28, 50, 82, and 126. With 82 protons and 126 neutrons Lead-208 hits two of these, so it's doubly magic.
"Smithers, get the Polaroid." (Score:2)
(For the comedy-impaired, that was comedy; bad comedy.)
God (Score:3)
God might or might not play dice, but fer sure he likes infinite series with no closed form. Also, has quite a sense of humor.
Lead-208 Nucleus of May .. (Score:2)
Is ChatGPT now writing your headlines?
Re: Lead-208 Nucleus of May .. (Score:2)
I think ChatGPT has better grammar.
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> Why else would they spell "force" with a capital F?
Because it is a title and title case capitalizes all but the trivial words, e.g., "of".
Implications ? (Score:2)
So nucleii may not be spherical. So what?
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So what, if the earth isn't flat?
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The hypothetical existence of super heavy elements is based on calculation models that assume spherical cores. Now we know lead already does not have a spherical core. So we have to rework everything for super heavy nuclei.
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Can I get "Earl Grey, hot?" now?
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