http://www.marxists.org/archive/marx/works/download/Engels_Anti_Duhring.pdf
On cosmology: Engels discusses Kant’s hypothesis of celestial bodies forming from primordial nebulae. “It is primordial nebula, on the one hand, in that it is the origin of the existing celestial bodies, and on the other hand because it is the earliest form of matter which we have up to now been able to work back to. This certainly does not exclude but rather implies the supposition that before the nebular stage matter passed through an infinite series of other forms.”
My own limited understanding is that Engels is wrong here with regards to the word infinite–there is a definite limit to the different stages; but he is right regarding the existence of stages before the coalescing of the nebulae. I speak under correction here.
“Motion is the mode of existence of matter. Never anywhere has there been matter without motion, nor can there be.”
Okay, this is me speculating: Might it be accurate to define energy as That form of matter that causes motion? And then we can define matter as That form of energy that is subject to motion. I might also be totally full of shit here. My knowledge of physics and mechanical motion and heat transfer &c is almost nil, which makes it very dangerous to speculate. But then, Dühring did, and it seemed to…er…never mind.
“All rest, all equilibrium, is only relative, only has meaning in relation to one or other definite form of motion.”
It was, in fact, in my lifetime (maybe around 1970?), that certain subatomic particles were held by some to be motionless relative to certain others within an atom, which was held out as a proof that the above stated law is incorrect. Or that was the argument I heard in high school. Of course, even if that hypothesis disproved what Engels said, the hypothesis only lasted until the next round of discoveries about subatomic particles.
“On the earth, for example, a body may be in mechanical equilibrium, may be mechanically at rest; but this in no way prevents it from participating in the motion of the earth and in that of the whole solar system, just as little as it prevents its most minute physical particles from carrying out the vibrations determined by its temperature, or its atoms from passing through a chemical process.”
“In ordinary mechanics the bridge from the static to the dynamic is — the external impulse.”
“Matter without motion is just as inconceivable as motion without matter. Motion is therefore as uncreatable and indestructible as matter itself; as the older philosophy (Descartes) expressed it, the quantity of motion existing in the world is always the same.”
“To be sure, it is a hard nut and a bitter pill for our metaphysician that motion should find its measure in its opposite, in rest. That is indeed a crying contradiction, and every contradiction, according to Herr Dühring, is nonsense.”
“From the dialectical standpoint, the possibility of expressing motion in its opposite, in rest, presents absolutely no difficulty. From the dialectical standpoint the whole antithesis, as we have seen, is only relative; there is no such thing as absolute rest, unconditional equilibrium. Each separate movement strives towards equilibrium, and the motion as a whole puts an end again to the equilibrium. When therefore rest and equilibrium occur they are the result of limited motion, and it is self-evident that this motion is measurable by its result, can be expressed in it, and can be restored out of it again in one form or another.”
Any motion that results in equlibrium initates motion that destroys another equilibrium, and so on (and here is an infinity I can grasp). This is one of the contradictions of motion; others will follow.
I should know but I don’t: what year(s) are we talking about here?
These discussions, before about 1880, are today meaningless, as they miss out both on general relativity and quantum mechanics. Motion, matter, and energy weren’t properly understood without GR, and both atoms and subatomic particles were badly misunderstood before QM.
(I agree with you, even in the mid ’80s they were teaching prehistoric atomic physics in high school, with little electron particles orbiting in their rings. But the physicists knew better; heck, Feynman shared the Nobel in 1965 for Quantum Electrodynamics.)
I’m not sure what this does to the philosophy discussion. Heck, we’re even breaking into thermodynamics, when we start talking about heat and entropy into a closed system, and what causes mechanical motion.
That’s a very interesting thing (to me, at least) for this discussion: what does Engels think about entropy? It seems relevant.
It was written in 1876-1878. I don’t remember if the book gets into entropy. I guess we’ll see. :-)
“These discussions, before about 1880, are today meaningless, as they miss out both on general relativity and quantum mechanics. ”
I am very leery of statements like this. It is like saying the discussions of Copernicus are today meaningless because we now know that orbits are elliptical rather than circular. More specifically, while Einstein’s work negated Newton’s, it simultaneously built on it; which means, in my opinion, to hear Newton’s arguments (or, rather, the arguments he stole from others and passed off as his own) against earlier explanations is still be relevant today.
And thirty years from now, when so much of what we know about GR and QM will be overturned, those discussions will still be relevant.
If there is one thing that Anti-Dühring makes clear, it is that knowledge is not established once for all time, but continually develops. The developments Engels speaks of were at the forefront of moving our understanding of the world forward from where it had been before.
“Might it be accurate to define energy as That form of matter that causes motion? And then we can define matter as That form of energy that is subject to motion.” Doesn’t this just sort of define them in terms of each other?
I need more tea before typing up my Chapter 6 notes.
Jen: I’m not sure. Maybe. But if we accept from the beginning that matter and energy are different form of the same thing (which, I believe, is accepted by current physics), then that might establish the relationship between them. Or not.
Words I had to look up: Cosmogony (having to look up the definition of a word in the chapter title gave me non-warm/fuzzy feelings about my future with the chapter overall, beeteedubs), and hey, I guess that was the only word. I did have to spend some quality time on wikipedia trying to remember how physics works. Fun fact: when I dropped out of high school, I was in the middle of physics and not doing much of the homework; I never picked up any physics class after that.
Without understanding much about Kantian nebula doohickeys, the first thing I got out of this chapter is that once again Dühring’s schematism can’t reconcile all the science things. This time his answer is to ask questions that are supposed to undermine Kant’s credibility; instead his own credibility is further shredded.
Two pages later I highlighted “logical-real” “in itself” “for itself” and made a note with sad little question marks because what is even going on here? Apparently we’re still on the pre-time primoridal self-equal state, but we’re explaining why it is wrong in terms of mechanical force — it still would require God to get from non-motion to motion.
A little later we have the line, “Motion therefore cannot be created; it can only be transferred.” Wikipedia helpfully informs me, regarding modern laws of conservation: “Momentum, energy and angular momentum cannot be created or destroyed.” This gets me a little further to understanding Engels’ use of the words motion and energy.
“Matter loaded with force” I’m understanding as potential energy, and still we’re talking about needing God to pull the trigger on it.
“it is a hard nut and a bitter pill for our metaphysician that motion should find its measure in its opposite, in rest.” … “From the dialectical standpoint, the possibility of expressing motion in its opposite, in rest, presents absolutely no difficulty.” … “As a good metaphysician he first tears open, between motion and equilibrium, a yawning gulf which does not exist in reality and is then surprised that he cannot find any bridge across this self-fabricated gulf.”
What I’m getting out of this is that we’re beating this dead horse to illustrate the futility of metaphysics. They think contradictions must be rooted out as impossible whereas dialectical dudes rely on contradictions as part of the natural world.
The next bit is about “the mechanical theory of heat,” and goes on to mention “it is certain to be full of defects as this still very young theory is as a whole, but it can at least explain what happens without in any way coming into conflict with the indestructibility and uncreatability of motion, and it is even able to account for the whereabouts of heat during its transformations.” So new science doesn’t mean bad science, and our understanding will certainly change in time, and that will be good. Understanding one thing relies on developments in understanding another.
In many ways this chapter only offered me repeats of earlier insights (with the exception of ‘contradiction’), explained differently with different scientific basis — even when the science was going over my head, it was the same points over and over. The benefit, I suppose, is that if I can vaguely understand one sort of science and my friend another, we can each of us find different footholds to the insights Engels wishes us to have.
I had a tough time and thus wrote FAR too many notes about this chapter. Sorry.
Well, following Einstein, one expresses the relationship between energy and matter as
e=mc^2
where the constant is the speed of light, but it is prudent to bear in mind the fact that by the latter part of the 19th century many physicists thought that they had more or less got it sorted, with a few small details to be wrapped up.
Uncertainty of whether one has got it right is a relatively modern addition to the armoury of scientists; as late as 1933 Rutherford confidently asserted that it was nonsense to believe that breaking the atom would provide much in the way of energy.
Twelve years later the atomic bomb exploded at Jornada del Muerto demonstrated otherwise; ‘now I am become death (Shiva) destroyer of worlds.’
Of course, Rutherford also said that ‘All science is either physics or stamp collecting’, notwithstanding his Nobel Prize for Chemistry; I doubt that he would have classed either Duhring or Engels as scientists at all.
On the other hand I have a fondness for his claim that:
‘An alleged scientific discovery has no merit unless it can be explained to a barmaid’.
I’m not a barmaid but I’m happy to volunteer for the role…
Jen:
‘Two pages later I highlighted “logical-real” “in itself” “for itself” and made a note with sad little question marks because what is even going on here?’ Yeah. That is not subject to human understanding. Because Hegel. But we don’t need it. Smile, nod, and move on.
‘“Matter loaded with force” I’m understanding as potential energy, and still we’re talking about needing God to pull the trigger on it.’ Yeah, I think so.
‘What I’m getting out of this is that we’re beating this dead horse to illustrate the futility of metaphysics. They think contradictions must be rooted out as impossible whereas dialectical dudes rely on contradictions as part of the natural world.’ That seems right, but he’s also pointing out that potential energy is still energy. However, the illustration with lifting the rock seems to make the point more clearly.
“So new science doesn’t mean bad science, and our understanding will certainly change in time, and that will be good. Understanding one thing relies on developments in understanding another.” Yeah. I’m glad you singled that out, because it’s one of my favorite passages. “Look, assholes, no one is saying we know all the answers now. We’re just saying the answers are knowable.”
Stevie: Right! Yes, good point. Not only can matter and energy turn into one another, but now we know the relationship between them. “it is prudent to bear in mind the fact that by the latter part of the 19th century many physicists thought that they had more or less got it sorted, with a few small details to be wrapped up.” Yeah, which is another reason I so like the passage Jen quoted about it being a new science.
Oh, and I’ll have a hard cider, please.
“Might it be accurate to define energy as That form of matter that causes motion?”
There’s a sort of hand-waving justification for this if you bend over backwards, I think (e.g. if you say that potential energy is just motion deferred over time) but I’d still say it’s basically wrong.
So for example, light (electromagnetic radiation or photons) has no rest-mass and therefore is not matter, but it carries energy according to Planck’s formula E = hν — based on the constant h and the frequency ν. This is different form of energy from the kinetic energy formula 1/2 MV^2; for a photon M=0, so it has no kinetic energy. Of course light moves, but it moves with exactly the same speed regardless of how much energy it carries, so its energy is sort of divorced from its velocity.
What about if you change your definition to just “that which causes motion” — no longer requiring matter?
Still, it seems not quite right. While energy is always responsible for motion* and is also inherent in motion (including of course heat, a kind of motion), not all forms of energy directly cause motion. So for example rest mass can be viewed as energy according to e=mc^2 and nothing needs to move for that energy to be there. In a sort of Mach universe with only one particle in all of space and time, evidently there can be no motion, but there is still the energy of the particle’s rest-mass.
For some other types of energy not connected to motion, I’d also nominate various kinds of potential energy, and also quantum states. An electron in “orbit” around a nucleus is not really moving in the classical sense, it’s just a sort of smeared out probability distribution. When you add energy to that system (e.g. when it absorbs a photon) you may kick the electron into a higher energy state, and that energy gain is not reflected in an increase in the electron’s speed as a particle, but in the change to the shape of the probability distribution.
*I think even this is technically wrong for some weird conditions around absolute zero.
Oh, well; I thought that might be too easy.
Still, motion per se is one of the most profound mysteries, as is dimension. Even if you decline to ask the purely mystical question “why existence”, still, the next obvious questions are “why space” and “why time”, and motion of course is change in space with respect to time. So even if that definition is not quite right in terms of our current understanding, it’s clear that matter and energy are inextricably intertwined with motion.
“My own limited understanding is that Engels is wrong here with regards to the word infinite–there is a definite limit to the different stages; but he is right regarding the existence of stages before the coalescing of the nebulae.”
That’s pretty reasonable; we now have a fairly well-defined limit in terms of the Big Bang, but in the case of our own Solar System, it’s clear that many of the atoms (or protons and neutrons) making it up were previously bound up in other stars before they became part of the proto-Solar cloud. (I’m inclined to think that Engels is partly repeating an idea of Hume’s here.)
“All rest, all equilibrium, is only relative, only has meaning in relation to one or other definite form of motion.”
Nothing wrong with this idea, which goes back to Galileo (and, in some respects, also to Leibniz), though I suspect Engels’ later relation of this to “the dialectic” is veering towards a sort of mysticism.
“… the quantity of motion existing in the world is always the same.”
Hmmmm… OK, that’s actually wrong, unless you replace “motion” with “energy”. Since you can have energy without motion (e.g., an atom or nucleus in an excited state does not have any more “motion” than an atom or nucleus in its lowest-energy, ground state, as Miramon pointed out).
(On the other hand, one can argue that it’s a bit unfair to critique a 19th Century writer for his lack of 20th Century knowledge.)
Steve: I keep editing your links at the top to be links. If you just paste the link it doesn’t work. You still have to use the link-button. I keep forgetting to tell you that.
“Because Hegel” Tshirt please?
The loaded gun and the rock lifting were both great.
Peter Erwin: I had lots of trouble in this chapter with the word “motion” in places where the concepts only made sense to me as energy. My eyes glazed over, my cat worried about my health, and eventually I decided to just run with what I could understand and not worry about learning 19th century physics.
Oh….that’s dumb. But okay.
Should we move on to biology?
A pedestrian wants to cross a busy street, but there is too much traffic that will not under any circumstances stop. When the light turns, so may cars turn from the side street that he still can’t get across. Finally in frustration he calls to a pedestrian on the far side. “How did you get over there?”
The other frustrated pedestrian on the far side of the street calls back. “I was born over here.”
In one of his bigger slips, Engels argues that Duhring cannot postulate a beginning state of the universe where lots of things have potential energy, like rocks in the sky, because the rocks could not get into the sky unless God lifted them there.
But then, he was arguing with Duhring who made so many horrible mistakes they were probably contagious. Didn’t Nietzsche say “Argue not with fools, lest you become one”? Or something like that….
Apart from the 19th century science, there was the argument about the distant past. Nobody knew then what happened in the distant past, and nobody really knows now. On the one hand there is the assumption that in the past things were pretty much like they are now. On the other hand is the assumption that they changed in some sort of pattern, from something else to this. The current idea is that they sort of go in cycles and sort of change. Each star may have formed from something more nebulous, and then go through a sequence of stages, and after it’s gone eventually you get a new nebulous area that can become a new star. This has happened repeatedly back to the time before stars could form, and and that changed back to the Big Bang.
The Big Bang does not have a lot of evidence. It’s just the only theory we have that fits the little bit of evidence available. It’s pretty much the only theory we pay attention to, to see whether it fits the evidence. It is a great big conclusion jumped to, but I don’t have a better theory and I won’t look for one.
So, what happened in the distant past? We look at light that reaches us today, and we make assumptions about that light and jump to conclusions. As near as we can tell things go in cycles, and they change progressively both. This is probably the best guess.
Engels thought about conservation laws. Things like “mass cannot be created or destroyed” or “Motion cannot be created or destroyed” or “electric charge cannot be created or destroyed”. It’s satisfying to create and believe in conservation laws. In practice we cannot tell whether a law is true, but when we go for a time without seeing examples of it failing, then we decide it is true. Sometimes we decide it is true even when we do see examples where it fails. Neutrinos are an example I may have mentioned before. Neutrinos are invisible undetectable particles. When we observe that energy/momentum/etc has been lost, we assume that undetectable particles took it away. When energy shows up from no detectable source, we assume that a passing undetectable particle brought it. As it turns out, this assumption is compatible with the known facts. Like, there are nuclear reactions in which energy disappears that happen inside nuclear reactors. And energy is more likely to reappear close to a reactor than farther away. This is compatible with the idea that the reactor created particles which travel until they release their energy etc, and there will be more of those particles close to the reactor than far from it because they spread out.
It would take something pretty strange happening for us to decide that conservation of energy was not true after all. I can’t think what would do it….
Basicly, it sounds like “metaphysics” is the study of what the world must be like, based on logical conclusions from whatever sounds plausible to human beings. Engels previously recommended going by the evidence instead, and argued that as each science matures the perceived value of metaphysics will decline. He was right. And yet he did some metaphysics himself, for example hypothesizing that before the nebular state of matter there were an infinite series of other forms. And modern scientists do it too. They try to be careful about testing things, but their unconscious assumptions get assumed without any testing because they do not imagine alternatives to them.
Engels heaped scorn on Duhring’s stupid ideas, and mostly managed not to make a lot of claims of his own. Things that today look like flaws in his evidence-based claims are OK. We have different evidence, Engels was going by what he had. The occasional unconscious assumption, well, we still do that.
Well, I’m just the barmaid but before we go it may be worth noting that, whilst we can do the turning matter into energy relatively easily, we still have a long way to go before we can convert energy into matter with the same ease.
What we can do at the moment is to make some sub atomic particles by whacking electrons and positrons in particle accelerators, using vast amounts of energy in the process, but these are not stable; no-one has ever held a press conference to show off some matter they made earlier.
One of the reasons they can’t do that is because energy can only be transformed into matter/anti-matter pairs, and all anti-matter wants to do is get together with matter and make sweet music, sorry, turn into energy.
Which takes us on to biology…
Stevie: Yep. We cannot yet turn energy into matter. But I’m convinced the key there is “yet.”
Stevie: Physicists are constantly talking about some matter they made. Making a Higgs-Boson is the current cool thing to make. Many of the products produced in colliders (electrons, protons, etc.) are quite stable (the anti-particles are also stable–they just tend to run into their (luckily) more numerous opposites) –just not in very large quantities. It takes a lot of energy to make a very small amount of matter.
Allowing for 19th century physics, Engels again does a fine job of skewering Dühring. At this point it is pretty clear that skewering Dühring is not a particularly challenging exercise but it does seem that Engels is having fun doing it.
As a physicist, I’m tempted to write way too much about this, but I’ll try to keep it in brief chunks. :D
* Momentum, not energy, is the thing associated with motion. (And this was definitely known back then, at least by physicists.) It’s always conserved, but not in the way you might expect. Imagine two people cuddling on the ice. They suddenly get into a fight and push away from each other — motion appears out of nowhere! *But*, their motions are in opposite directions; if you add up the momentum, it cancels out. That’s the sense in which motion is conserved.
* You might have read that in special relativity, time and space are put on an even footing. It’s more general than that; any physical quantity that points somewhere in space has an associated “time component”. For momentum, that turns out to be energy. As you change your own speed, the apparent motion and energy of objects change, but there’s a particular combination of them that stays the same. Whether something is “at rest” or “in motion” depends on your reference frame, but there’s a something that *doesn’t* change. (This is very typical of relativity; it wasn’t that suddenly everything was relative, but that we were confronted with new, less intuitive absolute quantities.)
* The modern view is that conservation laws emerge from deep underlying symmetries of nature. Conservation of momentum means that the laws of physics don’t change from place to place. Conservation of energy means that the laws of physics don’t change over time. (This was shown Emmy Noether in 1915; she was chiefly a mathematician, but it’s now considered one of the most important principles of theoretical physics. http://en.wikipedia.org/wiki/Emmy_Noether)
“And thirty years from now, when so much of what we know about GR and QM will be overturned, those discussions will still be relevant.”
We’ve actually learned a lot from previous scientific revolutions. In a sense we know that the current theory of the world is “wrong”, but we’ve developed an understanding of exactly how approximate theories emerge from more fundamental ones. Obviously the world could still surprise us! But we at least think we have a pretty good grip on how the current understanding connects to more fundamental models, *even without knowing what they are.* (http://en.wikipedia.org/wiki/Effective_field_theory)
Steve B
Hence my careful wording :)
Steve H
It may help to take a practical example; the Large Hadron Collider at CERN uses minute amounts of hydrogen. The first part of the accelerator strips hydrogen nucleii, consisting of one proton and one electron, of their electrons, leaving protons which are what is needed for lots of fun in the largest toy ever built.
But the LHC is not making electrons and protons in the sense that Steve B is interested in; those are already there in the hydrogen which is fed into the LHC.
What Steve B wants to know about is the possibility of making matter from energy, which is why I replied as I did; part of the kinetic energy of the colliding particles is transformed into new particles.
But we can’t hold onto those particles and assemble them into atoms for a variety of reasons, though I like to remind people about matter/anti matter pairs as a tribute to Scottie. Admittedly the matter/anti matter imbalance in the universe is one of the largest current question marks in physics, and people are beavering away on it, but I’m a barmaid and can therefore get away with a Star Trek reference…
I believe — not entirely sure, perhaps Starwed can comment — minute quantities of matter can be converted directly from energy through any means that suppresses virtual particle pair annihilation. If a virtual particle is converted into a real one through some means like laser containment in a magnetic field (I *think* that’s one approach), or through some kind of negative energy application (I *think* that’s another, as with the Casimir effect) then you’ve just created matter from energy without using any matter directly in the process like is the case in a collision.
Miramon:Hawking radiation is another potential method in that list (I think).
Stevie (We have a surfeit of Steve forms):My understanding is that the LHC (and other colliders) is actually making new particles. When the accelerated protons collide some of the kinetic energy is used in the creation of new particles. As Miramon (and you) mentioned, these can’t really be used to build up actual physical matter that you can hold in your hand.
J Thomas:
“The Big Bang does not have a lot of evidence.”
I’m going to have to disagree with you there. There is a *lot* of evidence for the Big Bang. (Even more showed up recently: http://arstechnica.com/science/2013/03/first-planck-results-the-universe-is-still-weird-and-interesting/)
Stevie’s hydrogen nuclei seem to each have one “i” and one electron too many.
Peter, I am not up to a detailed argument. I am concerned that essentially all of the data about the universe over the past X billion years comes from electromagnetic radiation arriving here in the last few years. It takes a complicated set of assumptions about how light travels long distances through space etc, to draw many conclusions.
You guys have a complicated set of assumptions that appears to be internally consistent. It appears to mostly fit the available data. It’s only natural to believe it.
Just, I would feel a lot more comfortable if you looked for the best backup theory you could find starting with very different assumptions, and kept updating the backup theories whenever you get a chance to make them better. When you mostly interpret things in terms of what you already think you know, there’s a whole lot of room for trouble.
“After the Big Bang, the cosmos was an opaque plasma, with too much energy to allow electrons and protons to form stable atoms. As it expanded, the Universe cooled, with stable atoms forming around 380,000 years after the Big Bang in an event known as recombination. This act both turned the Universe transparent and released photons, many of which have traveled uninterrupted into the modern era.
“While these photons were in the ultraviolet range at the time of recombination, the expansion of the Universe cooled the photons as well, so today they lie in the microwave portion of the spectrum. For this reason, the light is known as the cosmic microwave background.”
The theory has gotten very complicated as niggling little facts came up that it either needed to explain, or that provided opportunities for elaboration. It’s easy to believe you actually know things. You could possibly even be right.
NotTheBuddha
I plead guilty on misspelling nuclei but you will have to argue about the allegedly surplus electron with CERN. I suspect that it didn’t occur to them that people wouldn’t know that nuclei is the plural of nucleus and that therefore there would be electrons in the plural, just as there would be protons in the plural.
Alternatively, they’re foreigners so what do you expect?
Steve H
I thought that was what I had written, but thank you for confirming it, anyway :)
Stevie, there shouldn’t be any electrons in the nucleus, hydrogen or otherwise.
Professor Flytrap explains it all: http://www.youtube.com/watch?v=hhbqIJZ8wCM
Stevie:Cool–I thought we might be saying the same thing. :-)
NotTheBuddha
I’m sure that Professor Flytrap is very good, but given a choice between him and CERN I tend to go with CERN on the grounds that CERN has got the particle accelerators and he hasn’t…
http://home.web.cern.ch/about/how-accelerator-works
NotTheBuddha, every now and then some radioactive nuclei will spit out electrons. They spit them hard and fast and those electrons are called beta particles. Was it that there were electrons in the nucleus all along, and they just lost one, or was it that they created an electron on the spot so they could spit it out? I don’t really know and it wouldn’t surprise me if anybody who is completely certain they know is mistaken.
Sometimes some radioactive nuclei spit out positrons instead. Are there positrons and electrons both inside the nucleus, or do they make one or both when they need to so they can spit them out? Again I don’t really know.
And what is the difference between having an electron inside the nucleus all along, versus being ready to make one on the spot at any moment? I’m not even sure I know what the difference is, or how you’d tell which it is if you had a good way to look.
The more I learn about this stuff the less I think I know. A lot of people seem to think they have it all straight. Maybe they’re right.
Stevie–
That’s a misstatement on the part of whoever wrote the blurb for CERN. The hydrogen /atoms/ consist of one proton (usually) and one electron each. Atomic nuclei consist only of protons and neutrons (or just the one proton in the case of most hydrogen atoms).
ETA: J Thomas is right to say that lots of weird stuff happens when you smash atoms, but under non-atom-smashing conditions the nucleus is considered to be “protons+neutrons, no electrons.”
CERN exists to smash atoms, of course, but I still think the website’s statement is an error.
Evergreen, it isn’t just atom-smashing. I’m talking about natural radioactivity that happens all by itself on its own schedule. Atomic nuclei spit out electrons and positrons.
True, nuclei contain only protons and neutrons. And protons and neutrons are made only of quarks.
http://en.wikipedia.org/wiki/Inverse_beta_decay
Quarks are elementary particles. But they can emit virtual W bosons when they turn from one kind of quark to another, and the W bosons then decay into electrons or positrons etc. Does that sound like an elementary particle to you? When they emit something that decays into an electron, was the electron inside the W boson all along? Was the W boson inside the quark all along? There might be people might have good solid answers for this stuff but they aren’t so good at explaining it to barmaids yet.
>Was the W boson inside the quark all along?
No, particles often have multiple decay modes. That is, there are many different ways they can decay, and there’s no way to tell ahead of time what will happen. Thus, there’s no meaningful way to say that the product of the decay was somehow “part” of the particle before hand.
You can’t even claim that the information about which type of particle it will decay into is somehow hidden from us, because that just be a type of hidden variable theory. (http://en.wikipedia.org/wiki/Hidden_variable_theory).
In contrast, the idea that protons or neutrons contain quarks gives all sorts of direct, testable predictions; they’re in no way hidden away from us. The simplest to follow is probably that they have a size; electrons and other fundamental particles are point-like, but composite particles have a non-zero radius.
The folks at Fermilab, also with particle accelerators, explain how electrons remain outside the nucleus:
http://www.fnal.gov/pub/inquiring/questions/bob.html
They further explain the removal of electrons from hydrogen atoms (not nuclei):
http://www.fnal.gov/pub/inquiring/questions/jackie.html
>Was the W boson inside the quark all along?
“No, particles often have multiple decay modes. That is, there are many different ways they can decay, and there’s no way to tell ahead of time what will happen. Thus, there’s no meaningful way to say that the product of the decay was somehow “part” of the particle before hand.”
Notice that at the level we now are on — discussing physics in english, not math — there is also no meaningful way to say that the product of decay was definitely not part of the particle beforehand. If quarks, elementary particles which somehow emit or absorb electron precursors while changing from one type to another, were to contain electrons and/or positrons, how would you know? It would mean that quarks are not elementary particles but are composed of other parts. How do we know they are not?
“You can’t even claim that the information about which type of particle it will decay into is somehow hidden from us, because that just be a type of hidden variable theory. (http://en.wikipedia.org/wiki/Hidden_variable_theory).”
See, this is the worst sort of quantum theory. People say you cannot make alternative hypotheses because they would be alternative hypotheses and therefore not allowed.
“The folks at Fermilab, also with particle accelerators, explain how electrons remain outside the nucleus:
“http://www.fnal.gov/pub/inquiring/questions/bob.html”
Well, yeah. They explain that electrons cannot fall into the nucleus because they have a ground state, and they can’t go below the ground state. And yet, sometimes when a radioactive nucleus is ready to decay, an electron will fall into the nucleus after all and allow it to follow that particular decay mode.
Classical physics is wrong because they decided that any time an electron changes direction or speed it has to radiate electromagnetic radiation and lose energy. Since electrons cannot travel in straight lines at constant speed, they must never move or they will radiate.
So QM solves the problem by never discussing or describing movement of electrons in atoms. They don’t radiate and you can’t see them move, all you can do is say where they are likely to be. Why don’t electrons fall into the nucleus? Because by their probability distribution they are very unlikely to be there.
The reason it is a problem to solve is that opposite charges attract, so there is a force that is thought to constantly pull electrons into the nucleus. Meanwhile, there is a separate problem that the nucleus is full of tightly-packed protons that have positive charges, and positive charges repel. Why doesn’t the nucleus explode? Physicists invented a binding force which holds protons in the nucleus and opposes their repulsion. One of a small handful of fundamental forces, originally invented entirely to explain why nuclei do not explode. (Except very occasionally they do.) Why did they not invent an anti-binding force to explain why electrons stay away? They were not in the mood for that at the time.
You can’t make this stuff up.
NotTheBuddha and Evergreen
Thank you, both.
About the only ways I can envisage CERN messing it up is if someone originally wrote it in French and then mistranslated it, or, perhaps more likely, they are having so much fun playing with particles that they delegated writing the blurb to the barmaid without first explaining it to her…
Stevie, I looked at your CERN reference.
“In the first part of the accelerator, an electric field strips hydrogen nuclei (consisting of one proton and one electron) of their electrons.”
Yes, somebody just used the wrong word. They meant “atoms” in place of “nuclei”.
Neutrons decay into protons when one of their quarks decays by releasing an electron etc. The quark which does that is thought to have a -1/3 charge, and when it decays it loses a -1 charge, leaving it with a +2/3 charge. No fractional charges are ever observed, they are a theoretical construct. There is currently no way to tell whether the quarks contain electrons or whether they create electrons when needed. Protons each contain one of the quarks that might be considered to contain an electron, and two of the quarks that might contain a positron. But this has nothing to do with using an electric field to remove an electron from an atom.
J Thomas:
>Was it that there were electrons in the nucleus all along, and they just lost one, or was it that they created an electron on the spot so they could spit it out?
It’s the latter. Beta decay involves a neutron transforming into a proton; as part of the process, an electron and a neutrino (more precisely, an electron antineutrion) are created. The result is conservation of charge (total charge of a neutron = 0; total charge of proton [+] and electron [-] = 0) and also conservation of what’s called lepton number:
an electron has a lepton number of +1, while a antineutrino has lepton number of -1, so the total lepton number stays = 0.
At the more detailed, fundamental level, a neutron is made up of 1 up and 2 down quarks. An up quark has a charge of +2/3, while a down quark has a charge of -1/3, so the total charge is 0. (All quarks have lepton numbers of 0, so the total lepton number is 0.) A proton has 2 up quarks and 1 down quark, for a total charge of +1. In beta decay, one of the neutron’s down quarks transforms into an up quark, producing a W- boson (this conserves the total charge, because the W- has a charge of -1, mathematically canceling out the +1 of the new proton). The W- particle then decays into an electron (which also has a -1 charge); since an election has a lepton number of +1, its creation is balanced by the creation of a antineutrino (zero charge, lepton number of -1).
There really is no electron hiding inside the nucleus (or inside the neutron, or inside one of its quarks, or inside the W- boson). Similarly, when an atom in an excited state decays by emitting a photon, the photon wasn’t “hiding” inside the atom previously; it came into existence as part of the emission process. If you like, you can think of “emission” as meaning something like “on-the-spot creation, followed immediately by ejection from the site of creation.”
J Thomas:
> I am concerned that essentially all of the data about the universe over the past X billion years comes from electromagnetic radiation arriving here in the last few years.
Well, I’m not sure how I can help you there, if you’re sufficiently suspicious of electromagnetic radiation ;-). Pretty much everything we know about other planets and stars and, basically, the entire subject matter of astronomy is based on interpreting “electromagnetic radiation arriving here in the last few years”. (So, for that matter, is a lot of science in general: anytime a geologist does spectroscopy of a rock sample, or identifies layering of strata, whether visually or via some kind of image processing, they’re relying on electromagnetic radiation.)
Of course, we understand electromagnetic radiation really, really well now …
>I would feel a lot more comfortable if you looked for the best backup theory you could find starting with very different assumptions, and kept updating the backup theories whenever you get a chance to make them better.
But there *are* people doing that.
Of course, you can’t “update” a “backup theory” if it’s really *wrong* — there’s not much point in updating the geocentric cosmology of Aristotle and Ptolemy. (You wouldn’t suggest that people spend time “updating” flat-earth theories, would you?)
>The theory has gotten very complicated as niggling little facts came up that it either needed to explain, or that provided opportunities for elaboration.
It’s actually a remarkably simple theory, and the things you seem to be complaining about are basic physics, which you can verify in laboratories on the earth. E.g., the opacity of plasmas, the recombination process, cooling due to expansion.
>The theory has gotten very complicated as niggling little facts came up that it either needed to explain, or that provided opportunities for elaboration.<
"It’s actually a remarkably simple theory, and the things you seem to be complaining about are basic physics, which you can verify in laboratories on the earth. E.g., the opacity of plasmas, the recombination process, cooling due to expansion."
Simplicity is in the eye of the beholder, I guess. If it were to turn out that the generally observed red-shift of light over long distances had some other cause than velocity of the sources, there would be a lot of rethinking to do.
It's plausible that velocity is the cause of that. But then, not so many years ago it was plausible that velocity was the reason that electrons don't fall into atomic nuclei.
"There really is no electron hiding inside the nucleus (or inside the neutron, or inside one of its quarks, or inside the W- boson)."
Really? What is the experimental evidence for that? How would you tell?
"Similarly, when an atom in an excited state decays by emitting a photon, the photon wasn’t “hiding” inside the atom previously; it came into existence as part of the emission process."
Of course the photon wasn't there. If it isn't traveling at lightspeed (at whatever lightspeed is in the particular medium) we don't call it a photon.
I know it’s a little bit late in the discussion, and Engels was writing about the same time Thermodynamics were codified, but I still think that of all the physics topics, the one most interesting to examine from this viewpoint is 2nd law/entropy. I mean, it’s all about the behavior of energy without external influence, and the results of applying external influence, and the tendency of diversity to tend towards equilibrium, but *never* the other way around.
Analogies are dangerous, but there’s a great opportunity to apply these ideas to social order and the nature of change.
(Besides, I’m pretty sure they still believed in the Ether in the late 1870s, haha.)
“Of course, we understand electromagnetic radiation really, really well now …”
Well, yes. But then, we thought we understood electromagnetic radiation really, really well back with Maxwell’s Equations 150 years ago.
Incidentally, I heard a story that when Townes invented the maser, he first asked various prominent quantum theorists whether it would be possible and they all said that no, it was incompatible with quantum theory. After they saw it worked, they thought it over and decided it was compatible with quantum theory after all. But I found his autobiography. He said that yes, he did ask prominent quantum theorists about it, and they instinctively said it couldn’t work because they couldn’t imagine a way to get a whole lot of gas molecules to have close enough to the same velocity etc that they could produce coherent radiation. It wasn’t that they carefully worked out reasons that it was incompatible with quantum mechanics, it was only that they didn’t see a practical way to set up the necessary conditions.
>I would feel a lot more comfortable if you looked for the best backup theory you could find starting with very different assumptions, and kept updating the backup theories whenever you get a chance to make them better.
“But there *are* people doing that.
Well, sort of.
“Of course, you can’t “update” a “backup theory” if it’s really *wrong* — there’s not much point in updating the geocentric cosmology of Aristotle and Ptolemy. (You wouldn’t suggest that people spend time “updating” flat-earth theories, would you?)”
No. The geocentric theory isn’t exactly wrong. If you were to update it, you would do all your solar system mechanics in the frame of the earth. A noninertial frame, with some complications and you’d get nothing valuable for putting up with those complications, but it’s a possible correct point of view. I don’t see much point to updating that one because I don’t see that it brings much to the table to do so.
Flat-earth theories look wrong to me. A spherical earth works. Flat earth theories cannot work well. I think you could make a workable cylindrical earth theory. See, the idea would be that as things go north or south they expand. They get bigger so that you can’t fit as many of them into the same space. Lines of latitude would appear to get shorter as you go north or south because your surveying equipment gets bigger, until at the poles a real length of 25,000 miles appears to be a single point. You might want to have a basicly cylindrical sky too. You could probably make it logically consistent. I can’t imagine why anyone would prefer it to a spherical earth. They accepted something kind of like that for relativity, but when they accepted relativity they had no other idea that even gave the right answers. Some people hated it, and others were eager for something to believe in that did not make sense, but in the end they could find no acceptable alternative so they were stuck with that one. Given a choice between a weird unbelievable cylindrical world where things expanded or contracted with latitude, versus a simple, obvious, spherical world, people will choose the latter.