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Radioactive decay is not a constant.

Discussion in 'Science & Technology' started by TheMailMan78, Jul 18, 2011.

  1. W1zzard

    W1zzard Administrator Staff Member

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    why? i thought current age of the universe is calculated from hubble's constant which is nowadays calculated from WMAP data but other data sources like galaxy observations gave similar results ?
     
  2. twilyth Guest

    Do they still use radioisotopes in treating cancer? I thought they used directed energy like the gamma knife - where you use low dose x-rays from multiple angles intersecting the tumor.

    Anyway, proton beam therapy is better and safer than either. The problem is that you need to build a cyclotron in the basement of your facility in order to offer this treatment and I think there are only 2 or 3 of these machines on the US east coast.
     
  3. Thatguy New Member

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    The standard model, is born flatly out of observational ignorance.
     
  4. Steven Douglas New Member

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    Sorry for digging up such an old thread, especially as a first time poster, but this is one I found intriguing.

    What I could not discern from what I have learned thus far is whether the decay rates of all radioactive materials are affected.

    If all decay rates are affected by neutrino interaction, this could potentially affect what we know about geophysics, and specifically Plate Tectonics. While it is commonly thought that the Sun was around 70-75% as hot during the Archean, the Earth was exponentially less depleted. It is also thought, based on the unusually high concentration of nitrogen in the Earth that a storm of neutrinos, mostly solar in origin, could have attacked the Earth through the Archean.

    From one paper:

    Simply put, and assuming an increase in neutrino bombardment equates to an increase in nuclear decay, could a storm of neutrinos from the Sun throughout the Archean caused the Earth to be much hotter than previously thought?

    This is intriguing to me because we are hard pressed to understand or reach a general consensus on why Plate Tectonics (by whatever mechanisms) ever got started on the Earth, let alone continues today.
     
    Last edited: Dec 3, 2011
  5. qubit

    qubit Overclocked quantum bit

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    @Steven Douglas

    I'm sorry I don't know enough about this to have a proper debate with you. However, what you say seems to make sense and I just want to welcome you to TPU! :toast:
     
  6. Steven Douglas New Member

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    @qubit - Cheers!

    Nothing to debate, really. I have an avid interest in geodynamics, but I am by no means an expert or authority. I was just throwing it out there as an intellectual curiosity more than anything. It's one of those things where a relatively small effect can seem only mildly significant on first glance, but when I think about it on actual geological timescales, and multiply the sheer number of actively decaying elements involved some 3-4 Gya, the ramifications for early Earth processes look staggering to me.

    Most of the radiogenic elements in the earth are fixed in quantity and have long been depleted, but if neutrino storms accelerated this depletion process early on, in ways nobody anticipated given the a priori assumption of decay rates as reliable constants - that could equate to heat production and heat flows on scales nobody has considered.

    Meh, fun to think about anyway. :)
     
  7. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    Plate tectonics are actually fairly easy to explain. Under our feet, about 95% of it is magma and other liquid metals which have currents and flows just like on the surface in the oceans. The other 5% is at the flow's mercy having no point of stability except itself. The crust forms naturally because of the temperature difference between the vacuum of space and the hot interior of the Earth. The plates are the result of the magma flows creating tensions on the surface which in turn, cause the plates to break where they are weakest.

    Basically, plate tectonics started in much the same way as slag occurs on molten iron. The iron is more dense than the crust and has internal flows because of the variation in temperature. The less dense slag is at the flows mercy.

    There's only two areas of parting consensus I know of:
    1) The Expanding Earth theory. That is, as the Earth cools, it expands in size. Just as someone putting fat on fast creates stretch marks, Earth growing (since skin is more flexible than rock) creates fissures which in turn form plates.

    The theory opposing it with more consensus is that Earth was always the same size more or less and the magma flows created the plates.


    2) The source of heat at the center of the Earth. There's theories from nuclear fission to plain old pressure. Obviously, there's no way to test the core of the Earth--only theorize about it.



    As for decay, it is a can of worms that will take a long time to unravel. The scientists studying it didn't think it had much of an impact but there is no way to prove it either way. All we really can be pretty sure about is the sequence of events--not when they happened relative to modern dates.
     
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  8. Bow

    Bow

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    :toast:
     
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  9. Steven Douglas New Member

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    It's actually not quite that simple. There is quite a difference between what is being commonly taught and what is actually known. Despite "molten slag", mantle plumes (of every shape size and ad hoc definition), rolling convection cells (whole or partial mantle) and other visualizations, we are still without an accepted mechanism for what triggers, causes and drives Plate Tectonics. That is not controversial, as I can give a ton of quotes to that effect from some of the most respected Penrose Medal winning names in the industry.

    Here is an excerpt from the USGS: (emphasis mine)

    That is actually a very mild, diplomatic way of putting it. It is not a simple question of knowing the basics as we try to refine the details. As a contributor and presenter to the GSA, I know firsthand the level of controversy that exists in this field. The only thing that is not controversial is the fact of controversy itself.

    "Alfred Wegener's theory of continental drift died in 1926, primarily because no one could suggest an acceptable driving mechanism. In an ironical twist, continental drift (now generalized to plate tectonics) is almost universally accepted, but we still do not understand the driving mechanism in anything other than the most general terms" - Walter Alvarez

    All that to say, Plate Tectonics, for as invaluable as it has been as a working paradigm, has produced as many questions as answers, and is still very much in search of fundamental, definitive support, after thirty years of enthronement as the reigning paradigm. That has nothing to do with alternative theories (e.g., "expanding/growing earth), but rather theories that fall firmly within the Continental Displacement/Plate Tectonics regime.
     
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  10. AphexDreamer

    AphexDreamer

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    You a geophysics major?
     
  11. Steven Douglas New Member

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    No, I'm actually an old man. My degrees are in physics and electrical engineering. I worked in geophysics on the mineral exploration side in my younger years (ground resistivity and ground/aerial magnetometer surveys). I learned from the geophysicists I worked with, and have a circle of geologist and geophysicist friends still, but I'm otherwise self-taught over the years. Even the papers I present are all self-funded, just an avocation for me.
     
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  12. AphexDreamer

    AphexDreamer

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    Ah very nice. I'm currently studying for Geophysics and found your post quite intriguing.

    But welcome to our forums, we are a decent bunch and you can guarantee we will be there in your time of need (and from my experience here, that isn't just tech exclusive).
     
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  13. twilyth Guest

    @Steven Douglas: Welcome. There are a lot us older folks here and it's always a pleasure to find a member with a rigorous scientific background.

    One of the theories I've heard that makes some sense to me is the idea that tectonics is caused by convection currents in the mantle and that these in turn result from radioactive decay of heavy elements like Uranium near the core. It seems to me that without some internal heat source, our core should have solidified long ago. How well regarded is this idea? Thanks.
     
  14. St.Alia-Of-The-Knife New Member

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    i remember a video where a 405nm laser was shined on thorium ore and there was an unexplained drop in gamma ray emission but i just cant seem to find the video...damn
     
  15. St.Alia-Of-The-Knife New Member

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  16. Steven Douglas New Member

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    There are more schools of thought than there are schools at this point, but that is at least a subset of one of the more popular ones.

    Generally speaking, one prevailing school of thought is that the majority of radiogenic heat producing elements are contained within the continental crust, such that heat flow becomes a function of secular cooling of the core and mantle and radiogenic heating of the crust.

    Kellogg and others have hypothesized over the past decade or so the possibility of a chemically distinct layer in the lower mantle with a substantial concentration of radiogenic materials to account for heat flow through the surface. This is but one of the many plausible conjectures posited, which can't be directly falsified, but only indirectly tested, while mostly inferred.

    Even the general agreement that exists about total heat flow is an adopted number based on approximations using a boatload of assumptions. We can't measure heat loss near mid-ocean ridges, and there are large areas over continents where heat flow is not measured - not to mention we don't know very much at all about radioactive concentration in the lower crust.

    How it's received, on the other hand, is another story. Like any new hypothesis, there will be followers just because it is a lead that can be followed. This one is among the more popular flavors of the decade, because it simultaneously reinforces the popular concepts of bottom-up whole-mantle convection and deep mantle plumes.

    Those who are engaged or wedded to their own theories tend to respond with either not responding, or else responding with the classic, "Is this really required?" Which, of course, means only that their equally plausible, and in their minds more straight forward or elegant, explanation is to be preferred.

    Here is an example [pdf] of how this is dealt with by Warren Hamilton, Penrose Medal winner from the Colorado School of Mines:

    I probably should have just quoted Hamilton to begin with, rather than shoot my mouth off and open a potential can of worms. But oh well. I really don't have a horse in this race - and I don't see a need for anyone to have one. There is so much that I don't know, especially as regards some of the more complex, and less comprehensible (IMO) work that has been produced. I tend to be more of a champion of "Multiple Working Hypotheses", as I oppose, in principle, the notion of paradigm enthronement of any kind. It is really unnecessary, and can lead to circular self-reinforcement, given how difficult it is to unseat an incumbent (like the Ptolemaic universe and other reigning paradigms).
     
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  17. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    I must be missing something because how, exactly, does fluid dynamics not account for plate techtonics? Yes, it is impossible to prove but from what we see on the surface, it appears to be a match. Actually, it wouldn't be very hard to produce a computer simulation and attempt to map out all the currents in the magma that would create the plate techtonic movements on the surface.


    It sounds to me like Warren Hamilton was unintentionally describing the need for the expanding Earth theory. Personally, I believe plate tectonics are a result of fluid dynamics and the expanding Earth theory. The expanding Earth theory can explain the annomalies in age, especilly under the Pacific Ocean. Fluid dynamics can explain other annomalies like the New Madrid Fault.
     
    Last edited: Dec 4, 2011
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  18. Steven Douglas New Member

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    There are thousands of such models, and they are anything but simple, unless you are talking about a mere visualization. I can do that with a simple rendering program, but it would be scientifically meaningless. I can also do a numerical simulation, but which assumptions do I plug in, and using which physics?

    One of the best, most respected modelers in the business is Paul J. Tackley of UCLA - I'll let him do the speaking on that one. None of the following is considered controversial: (pdf, part 2)

    The rigid lid problem is just one problem geodesists and geodynamicists face with models. There are many others - so many variables, known and unknown, especially at depth, with so many observable behaviors of the lithosphere which must be interpreted correctly and accounted for by any model.

    Warren Hamilton, an absolutely brilliant man whom I have talked with at length, has a very specific general theory of his own which is explicable, plausible, and which he believes accounts for all observable lithospheric behavior. But to interpret a call for new paradigm cannot be interpreted by anyone as a call for their favorite paradigm.

    Hamilton's problem, one faced by so many in his position in the mainstream, is not that he must dethrone the PT paradigm itself; only a few major governing assumptions surrounding that paradigm, which have become untenable, fraught with problems, and do not fit with what we now understand after 30 years of PT enthronement. That is a daunting task on its own, even for one in the mainstream.

    Once the fictitious monster was erected and given putative life, every governing assumption, right or wrong, became vital enough to be defended, even with numerous ad hoc repairs if it was later contradicted by numerical modeling or observation.

    I don't personally dismiss out of hand alternate theories of any plausibility, regardless how outlandish seeming at first. That includes Expanding/Growing Earth theories, in all their forms, which offer explanations for many observable phenomena while giving rise to many new problems - big ones, like how to account for the expansion itself, which cannot be volume alone, due to gravity problems, but in some cases a seven or eight fold increase in the mass of the Earth which would be required over a relative short span of geological time (~250My). Furthermore, if a theory involves the assumption of a changing constant, or completely new physics with no foundational support (like in the case of Neal Adams), even then it does not mean that their theories are not true; only that the worker championing that theory is faced with even more daunting tasks - ones usually left to others (e.g., "My theory of FTL travel can explain everything - all we/you all need to do is find a way to make dilithium crystals..."

    One of the major problems with paradigm enthronement, rather than a continued Multiple Working Hypotheses approach, involves conclusions that are hastily and prematurely drawn based on observations that falsify an existing theory. The work of Wegener, Hess, Vine, Matthews and many others had successfully and conclusively established that at least some continents were, at one time connected, and had since been displaced - by whatever mechanism which was yet to be established. That much was proved to everyone beyond all doubting. Wegener's "continents plowing through oceanic crust" was untenable (mere conjecture, Wegener did not propose this as part of any theory, but just threw it out there as one plausibility based on what was known at the time).

    Another plausibility was "slag floating on molten mantle", with rolling convection cells, and the cyclical creation and destruction of oceanic crust. It was so visually and intuitively plausible, in fact, that it became enthroned as part of the theory just because it makes sense - even though we had no way of knowing at the time if it was true. When that happens, what is known and unknown, including fundamental untested assumptions, are conflated to form the skeleton of a hypothesis which must be later fleshed out - on the a priori assumption that it is all essentially correct. Thus, anything that falls outside that paradigm can, and often is, dismissed without further inquiry.

    In this way, science can often be like a friend who asks you to dinner, takes you to McDonalds, lets you know that anything on the menu is available for selection, and then asks you "What kind of a small orange soda would you prefer?"

    Anyway, I'm rambling now, and need to stop. All this to say that I think that the pouncing onto and latching hold of anything based on a visually intuitive plausibility is not necessarily a bad thing. It's just a lead; one more avenue to explore, so you follow it. But you don't enthrone it. You don't seal off all other avenues of exploration, and channel all resources into a favored channel, regardless how compelling. If it is truth, it will need no defenders, but will reward all adherents - as it reveals itself as such over time.
     
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  19. qubit

    qubit Overclocked quantum bit

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    This is how you do it, put the bit after the = sign between tags: [yt]vtughFzaIlo[/ yt] (just take out the space after the /)

    Here it is embedded:

     
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  20. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    And that's the heart of it, no? We don't know how fluid the magma is and it is difficult to theorize about because there is an enormous volume of it, has variable densities (closer to the center, the more dense it is), variable heat, and variable pressures. You're right, it would be difficult to make a working physics model because there's too many variables and not enough information.

    I think there's only one way to get a definitive answer and that is to start construction on probes. At the same time, what applicable knowledge could be gained from this? It would no doubt be very expensive requiring a lot of very exotic materials in order to withstand the heat and pressure. Something has to offset/justify the cost.


    The core cooling. As it cools, it causes the crust to grow thicker.

    Mass likely didn't change--density decreased. If mass did increase, it would likely be the result of an extraterrestrial body colliding with the Earth and their respective masses joined.

    Random thought: Don't major earthquakes cause days to become a fraction longer? Would that not be explained by the Earth getting a fraction larger?
     
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  21. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    Here on TPU we don't "ramble". We "discuss at great length even to the point of nausea".
    Until you start seeing tl;dr you are good to go. :toast:

    You commented that you are an "old man". How old (if you don't mind me asking)?

    One more question, you said that you hold a degree in Physics. Could you switch to writing computer games for a living? The physics in a lot of the games are terrible and the industry needs you. :)

    Oh btw ... welcome to TPU.
     
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  22. Steven Douglas New Member

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    The very best we can do with probes at this point, and it is being tried, is tantamount to a tiny pinprick on the skin of the Earth - just at one point, and not relatively deep at that. It is a massive undertaking with results that are extensively studied, and teaching us a lot.

    The word crust has to be qualified, same as the core, as differentiated from the mantle and the crust, all of which cool at different rates, some of which are thermally insulated. Differentiated crust (continental and oceanic) "thickens" by top-down cooling and solidification, but there is a finite amount of chemically distinct continental crust, which does not "thicken" (i.e., the actual mass quantity of continental crust does not increase) with cooling.

    An increase in density and not mass would necessarily, and by definition, entail a contraction, not expansion - which would then beg a completely different explanation for new oceans and the displacement of ancient continents. The only way that you can have an expanding earth by way of increased density is to make part of the interior Earth hollow (becomes more dense by displacement) - which may be covered by an entirely different theory described using that word.

    A mass increase in the Earth based on collisions or accretion would still need to be explained, including some kind of evidence, including an explanation of how a manifold increase in mass resulted in a continental displacement which occurred only in the past 250 My.

    Nothing I want to argue or entertain, necessarily, I'm just describing some of the challenges proposed by any proposition, as I see them.

    Shorter, not longer, but not based on a change in diameter. Google "earthquakes lod" (sans quotes) - lots of stuff on that.

    51-ish. Not really old, just too old to have "a major" in something. lol

    Cheers!

    No, my code writing ability is atrocious, I'd just make the games worse. I do like playing games, but could never write them. And, btw, I don't hold advanced degrees in anything. No Masters, no PhD. Moreover, I have Huntington's Disease - initial onset - which has caused a deterioration of my brain to the point where I can't even do the math any more - even relatively simple stuff. Thus, a lot of stuff I won't even get very far into here, and will readily cave in and turtle on arguments, just to avoid taxing myself. Gotta budget those interests, so whatever I talk about here, take it all with a shaker of demented salt!
     
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  23. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    Yes, which is why we need a device that will bore through the crust, hit the mantle, and presumably fall to the core. It would have to be extremely dense and very thermo-resistant (hence expensive).



    The thickening of the crust would presumably be composed of the same material in the mantel closest to where the two meet. So yes, chemically they're likely not to be the same.



    An increase in volume with no increase in mass means a decrease in density. I said "density decreased," not increased.


    You reference 250 My frequently. How was that number reached? Radioactive decay?


    That subject (earthquakes shortening days) still confounds me. Could you explain how, exactly, that happens in a sentence or two? Is it due to the jolt of energy released when the pressure is released? I mean, the length of day is strongly tied to the Moon. How can something minor like that, here on Earth, have any impact on the length of day.

    The links suggest "Earth's mass shifted" but that's about as descriptive as calling the Sun orange.
     
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  24. Steven Douglas New Member

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    No, radioactive decay is involved, but it's based on a very liberal estimate of the age of the very oldest ocean floors, along with an even looser tie-in with the Permian Triassic mass extinction event (The Great Dying), and the Siberian Traps of similar age, which preceded the creation of what are now the deep oceans, and which many believe was a triggering event of some kind, or coupled in some way. The actual oldest "large body" ocean floor is in the western Pacific, near the Mariana Trench, and has been dated to 180 My. All continental crust is much, much older.

    Just remember that when we're talking about possible LOD changes based on earthquakes, we are talking MINISCULE hypothetical changes. Even the moon's effect on the LOD is based on tidal forces on a body that is not perfectly solid. If the Earth was a perfect solid, there would be no shifting of mass (especially the oceans), and no change in rotation.

    The best lay explanation I can offer: Imagine yourself freefloating in space. Without something to push away from, you will remain in one place (or, at least, on the same Newtonian trajectory). However, you can, by shifting your own mass internally, cause yourself to rotate - quite fast, in fact, without anything but your own mass pushing against itself. You won't go anywhere, but you will rotate. And, conversely, you can "reverse" this rotation by shifts in the opposite direction. That's really all that happens with an earthquake or a tidal shifting of mass caused by any external body (the sun has tidal effects on the Earth as well).

    Technically, every single movement you make can cause a miniscule, albeit unmeasurable and negligible, change in the LOD, as your mass, which is part of the Earth, shifts. So when people say that an earthquake caused a shift in the LOD, it is not a question of whether this occurred, but only how substantially it occurred, and in what direction.
     
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  25. Steven Douglas New Member

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    My mistake, sorry. An increase in volume, and corresponding decrease in density necessarily means an ENORMOUS decrease in surface gravity over time (inverse square law - [corrected]). That poses many problems, and is untenable on many fronts, only one of which is trapped sediment dunes of a given height that would have been impossible under increased gravity. It also poses a problem for dinosaurs, who are already being made much lighter and stronger than ever previously thought in order to fit the assumption of fixed surface gravity. A decrease-in-density/increase-in-volume would strain that even further, crushing the dinosaurs, even at their already adjusted putative mass and strengths. The only way around that is to increase mass along with volume - and not a small increase in mass, but by many times the original mass of the Earth.
     
    Last edited: Dec 4, 2011

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