User talk:Sbharris/archive3

This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Archive #3 All messages from the beginning of April, 2007 to end of June, 2007.

barnstar for persistence

Hi. I'd like to award you a barnstar for your persistence in dealing with various people calling you a troll. In all the arguments of yours I've seen so far, I find myself agreeing with them all, and you put forwards your points very well IMHO, without getting too arrogant. Well done! (Sorry there's no actual barnstar image accompanying this text - not actually found the appropriate one for it yet!!!) --Rebroad 14:09, 9 April 2007 (UTC)

Blush. My first imaginary barnstar, a subjective anonymous internet award, even when visible. A record in virtuality, this must be. But thank you, anyway! Please free to add such sentiments to TALK pages, on RfC questions. Most of my work here on WP has been in cleaning up physics, chemistry and medical articles, plus some Wild West history, but all newcomers to Wikipedia see things they'd like to change about the basic structure of how the place works (ie, Village Pump stuff), and we have fresh (but ignorant) eyes. That doesn't make us not worth listening to. Most of progress in science and technology is made by such people (after the old-timers have cleaned up the major obvious errors, and pointed out that certain wheels have already been invented.) So I persist, on and off. It's not really (though it must sound like that to a few others, who love harmony) that "I'd like to have an argument, please". When I have one of those days, I can always have a genuine Ultimate No Limits fight on Usenet. So can everybody here. We all know that. Since there are better places than heavily-proctored WP to Troll, I think that we should assume, WP:AGF that most of what looks like trolling on WP, is really newcomers trying to keep WP from sucking.

(Oh, and by the way, we've all had the experience of working on a long edit of an article, just to see it "wiped out" by somebody adding a comma or something, while we were editing. But all is not lost, there. Simply use the "BACK" arrow on your browser to see your old edit screen again, use your browser "copy" to capture on the edit page any freshly edited text you just went through (even the whole article), then go to the newest version of the article, to into edit mode, and paste yours in, then erase the old. If the minor edits have occured since then, and are good ones, it's easier to add those in manually before you "save", to avoid wiping out the other guy's stuff (since it's usually only minor stuff). The only time all this doesn't work is when two users are trying to make major edits at the same time. Then one user has the responsiblity of integrating (usually the guy who lost out by doing the last "save" since the page was opened by two people) SBHarris 21:05, 10 April 2007 (UTC)

Energy lead

Hi Steve. Pardon me, but I have the following objections to your edit to the energy lead, and I'm hoping we can work to clarify your edit to come to a consensus.

• The addition of the word "sometimes" to a sourced statement modifies the statement being sourced, invalidating the sourcing.
  • Right you are. The problem is that the source is, strictly speaking, wrong. We should probably delete it and look for a better one.
• The bit about the "sole exception" to the definition (not "rule") is a parenthetical inappropriate to a lead section. I do not believe it assists in providing an accessible overview as called for by the Wikipedia lead guidelines, because it digresses into a tangent too early in the article.
  • Definitions very often have the problem that they aren't inclusive, and exceptions must be discussed right up front. Look at the LEAD for mammal and see what problems the monotremes give that definition, right up front, with need to use words like "usually", and digression into issues like placentas and mammary glands. There's no avoiding this. Nature is sloppy and so is language. It is usually very hard to make the two (nature and language) exactly congruent, and be terse at the same time.
• By a similar token, it is inappropriate to introduce a new term ("degraded energy") that is not wikilinked within a lead.
  • Here I see your point, and must agree (and will remove). On the other points we're probably far apart. Heat energy is an important type of energy in the universe, but SOME of it is NOT able or available to do work in all real circumstances. That leaves a big problem with trying to define all energy as ability to do work. That's just wrong. It's too wrong even to stand as a temporary overview definition, just as it's wrong to say mammals are warm blooded creatures that have hair, give milk, and bear live young.
• I hope that you can address these concerns as well as elaborate upon, and source, your explanation of degraded energy elsewhere in the article. Robert K S 09:58, 12 April 2007 (UTC)
  • Source. Well, any good chemistry textbook. But I don't have one that attempts to define energy except by treating heat as quite a different kind of energy, to be considered differently in all definitions as a separate quantity-- one that must simply be added to other kinds of energy (all of which others CAN be interchanged) in definitions of E.SBHarris 00:21, 13 April 2007 (UTC)

Brandt

I changed David to Daniel with an explanation on your BLP comment and am letting you know as a courtesy, SqueakBox 01:17, 17 April 2007 (UTC)

Wups. Okay, sorry for the error. SBHarris 01:21, 17 April 2007 (UTC)

Advection and Advection equation

Hi, I merged these two articles a while ago without realising it was contentious. I have proposed it to re-merge them at Talk:Advection and thought you might like to comment. Rex the first ^{talk | contribs} 09:01, 18 April 2007 (UTC)

I made a comment. I didn't before since I thought the merge was fine, and couldn't imagine why somebody would want a separate article for the math (nothing was lost in adding it to the advection article, and if it was, the two should be totally combined so that nothing at all is lost except redundant commentary). Particularly since the math part is abbreviated even in the equation article, and needs a lot of work, anyway (defining variables used, etc).SBHarris 19:03, 18 April 2007 (UTC)

Sorry, I must have got confused. I merged them a while ago and I thought you un-merged them here so I thought I should check with you first. Rex the first ^{talk | contribs} 08:38, 21 April 2007 (UTC)

No, my personal recommendation is get all the material from the math article into the advection article, and mark the equation article for "proposed deletion" (reason: redundant). SBHarris 15:53, 21 April 2007 (UTC)

Gere

Hi, I noted your comment on the Wales talk page about the Richard Gere dispute. It may be helpful for you to leave a comment on the Gere talk page. Thanks. FNMF 06:30, 28 April 2007 (UTC)

Hi, I've replied to your comment on the Wales talk page. I think your concerns are totally valid, but I believe policy offers more guidance on these questions than you seem to. No doubt you have reached this conclusion because of what you have observed happening in practice. But I would suggest that what happens in practice comes about largely from people either not understanding policy sufficiently well, or deliberately ignoring policy when they feel like it. This is particularly the case with BLP entries. Often, a concerted group of editors will wish to indefinitely "discuss" these entries, and editors attempting to enforce policy get caught in the trap of arguing about matters other than strict policy. In my experience this is a mistake. For me, a key part of the BLP policy is the example of the messy divorce: "If its not notable, verifiable, and important to the article, leave it out." Notability is key to this sentence, but the least understood part of the sentence. My belief is that it is easy for editors to ignore the notability issue, partly because lots of interesting information might then be excluded. But lots of interesting information should be excluded, if the entry is not the right place for that information. If concerned editors uniformly attempted to enforce the notability requirement in relation to BLP entries, I think the editing culture at Wikipedia would benefit. I apologise if it sounds like I'm lecturing you. That's not my intention at all. I'm just taking up the opportunity presented by your comments to reflect on these issues further. Thanks for your interest in the issue, and consider leaving a comment at the Gere entry! FNMF 05:15, 30 April 2007 (UTC)

Thanks for the polite response. I can only note that Wiki policy is widely ignored. However, to Wikipedia credit, I notice (on just checking) that the bio articles on the Duke lacrosse team members have all been deleted, and redirected back to the Wiki on the scandle itself. That happened very recently. SBHarris 05:22, 30 April 2007 (UTC)

Due to the unwillingness of FNMF to find consensus on this issue I have taken the discsussion of the Gere/Crawfod letter to the BLP noticeboard. [1]. Please feel free to comment. Sparkzilla 10:15, 30 April 2007 (UTC)

Hemoglobin

Hi there. I have just undone your addition of a second image to show the R to T transformation. [2] The reasoning is that, although the second image does show all 4 chains and you could argue that two images are better than one, the text was being crushed up along the left hand side (as the second image is so big) and the sigmoid curve image (which is already some distance from the text referring to it) was being pushed further down the page. I would normally leave the article alone and have a chat first but as the Hemoglobin article is (IMO) pretty good and probably looked up by quite a few people I wanted to make sure that it was still readable while the images are sorted out. (I have spent about half an hour trying to get the 2 images to fit properly with the text and not look awkward but without success.) I have also left this same message on the article's talk page. Hope that's okay. All the best.Mmoneypenny 22:02, 28 April 2007 (UTC)

Advection and advection equation merge

What in the devil are you doing?? If these are to be merged, it should be under advection, not advection equation. What you've done is like merging redirecting energy to an article called energy equation. That's backwards. The general topic comes first, the math later. Put the math in a subset of the main article, where everybody expects to find it. As is done for all physics topics where there is only one article. Are you trying to make a joke, here? SBHarris 23:50, 29 April 2007 (UTC)

Sorry I merged the wrong way around, I meant to do that. Next time I merge pages I will make sure I check. Rex the first ^{talk | contribs} 09:54, 30 April 2007 (UTC)

Thanks for the merge. I did more work on it, like merging the see also sections, categories, and inter-language links, and I removed a few links which pointed back to article, so just post-merge cleanup. I hope you're fine with that. Cheers, Oleg Alexandrov (talk) 03:37, 1 May 2007 (UTC)

PS. By the way, starting a comment with "what in the devil are you doing" can scare the heck out of newer users who made a honest mistake. Just thought I'd let you know. Oleg Alexandrov (talk) 03:37, 1 May 2007 (UTC)

True enough, but my thought was that any user (new or not) who knows enough about the system to know HOW to merge two articles and create a redirect, knows enough, ipso facto, to do it right. The idea that anybody could do this the wrong way around non-deliberately, and by mistake (given all the multiple steps you have to go through, to do it so it works, but works WRONG), never even occured to me. It's not a matter of a missed keystroke. I still find it bizarre, but am quite willing to AGF and take your word on it, and am glad it's now been corrected. No harm, no foul. You ended up doing good work and the net result is a vast improvement. SBHarris 04:00, 1 May 2007 (UTC)

Heinlein on BLP

Have you had a chance to read For Us, The Living? You recent posts about the BLP policy have been channeling RAH's ghost. KonradG 03:35, 8 May 2007 (UTC)

I often channel RAH, but rarely intentionally. I actually read FUTL when it was published a few years ago, but remember it only as a fairly uninteresting economics rant. I don't remember a thing about privacy discussions. So you'll have to connect me...SBHarris 23:04, 8 May 2007 (UTC)

Looked through the book again. The part I was referring to was the discussion of the second constitution, created after the overthrow of the religious fundamentalists. Specifically, a right to privacy which trumps even the right to free speech. Something about dividing life into "public sphere" and "private sphere", the latter being fairly broad and including things such as work carried out as an employee. Activities in the private sphere sphere could not be printed or publicly discussed without the person's consent. If I understood it correctly, the restrictions applied to anyone rather than just the government.

And yes, the economics rants were painful. Heinlein certainly wasn't the first or the last intelligent man to be taken in by that convoluted logic, but that doesn't make it any less ridiculous. KonradG 02:17, 1 June 2007 (UTC)

I'll see if I still have my copy to see how precient the stuff is. In light of the US supreme court finding a "right to privacy" in the 11th ammendment so they could overturn Massachusetts' anti-condom laws in the late 1960's, there's probably some good libertarianoid future-predictive stuff here. Since these laws (like much of the antidrug laws, following US alcohol prohibition in 1920) were motivated by religious-conservative voters, Heinlein probably correctly anticipated some of America's continued Puritanism, as well as (some) of the backlash. Alas, we (like other countries) still have wild swings back and forth on what is considered "public" behavior. And today, since just about anything you do in your bathroom or bedroom affects your public life and your burden on the taxpayer in these days of publicly funded healthcare, it's a problem. And very few SF authors could have predicted what is surely coming, which is David Brin's "Transparent Society", where everything you do and say outside of your home will be permanently documented and probably ultimately internet-searchable by anybody interested. Today we have Wikibios of "semi-notable" people like corporate CEOs and minor team and band members. Tommorrow, you can have U-tube footage of anybody you like, going out the front door to pick up their morning paper, taken by the routine survailance cameras which cover all public space. Comb your hair and remember to smile. SBHarris 03:32, 1 June 2007 (UTC)

P.S., GADS, did that comment get posted on my main user page? Serves me right for forgetting to check it regularly. Thanks. SBHarris 03:32, 1 June 2007 (UTC)

Energy (chemistry)

Hi, just to let you know that your old friend created Energy (chemistry), in case you are interested. --Itub 11:32, 9 May 2007 (UTC)

electric chair in Philippines

I've reverted your last change here. 1) 2 to 4 is a 'few' in my book; 5 or more is quite adequately covered by 'several'. 2) It is confusing to give the impression that use of the 'chair' _ended_ in 1976, when the penalty remained on the statute book for many years more - the situation is not like the USA cases pre and post Furman. Linuxlad 09:33, 12 May 2007 (UTC)

Answer: The use of the chair did end in 1976, since although the statute remained on the books past then, the death penalty ended later, so 1976 turned out to have been the last use. That's true of the last use for any execution method, since there's not a one anyplace that isn't in theory capable of being brought back. These things are always understood as "as of this date the last use was..."

Second, I think it's silly to use a phrase that is vague and liable to misinterpretation, when for the same space (or less) as you use for "several" decades, you can be more nearly exact, and say "five." You can even use the exact dates for the same space (1923-76) and give MORE information. So what in the world possesses you to think that your use of "several" is in any way better? You can argue about what "several" means to you, and I can argue about what it means to me, and THAT is a silly argument, given that it's not a well-defined word in English, and we're not stuck with this word, except as you demand it (in which case I think we need the opinions of some other editors). For the record, my online dictionary (try it on the web) actually says "several" is "more than 2 or 3, but not many." Well, how many is "many"?? In English, the term is often tied to the badness or goodness of a thing. Five birthdays or birthday presents isn't many. But five assailants at your mugging, or getting shot five times during the process, would be many. If the Phillipines electrocuted people for 5 decades, I would have called that many. If they'd merely had their political freedom for that many decades, I wouldn't. See how it works? In any case, it's a silly thing to debate, so why don't you change it to something simple and direct and not capable of being misunderstood? SBHarris 21:15, 12 May 2007 (UTC)

Steve, well I've read your answer and almost completely disagree, but life is short so I shan't fight you on it :-) Bob aka Linuxlad 22:12, 12 May 2007 (UTC) PS - more relevant for a medical man - who was the NY doctor who did self-application of volts to find the level that made him loose consciousness. (It's on the web somewhere...)

You've got me, there. I can't find it. It must've been well after Kemmler, since at that time they seem to have collected every electrical story everybody could find, with animal experimentation observations, too. No firsthand accounts by doctors do I see. The story reminds me of all those doctors in Lawrence Altman's book Who Goes First? And the University of Utah experiments in which doctors proved upon themselves that a dose of curare sufficient for complete paralysis (requiring intubation) did not produce unconsciousness. And Haldane (a physiologist), who did that famous series of experiments upon himself to see what partial pressure of oxygen was needed to induce seizure and unconsciousness (seven atmospheres for some minutes), and what the prodrome was. He suffered back pain from the seizure convulsions, but survived this routine a number of times. See London's story A Thousand Deaths. In the old days, they had "sand." SBHarris 05:04, 13 May 2007 (UTC)

No, I'm 95% certain it was prior to te first execution, 1880s-ish, and the guy found out that a head to body application of several (it's that word again) hundred volts made him blackout.

I did once accidently self administer about 500 VAC from my lips (microphone) to one arm (touching the top of a 600-0-600(??) transformer that powered my Radio amateur rig) - the effect was like being slammed over the eyes with an iron glove - perhaps NOT to be repeated 40 years on :-) Bob aka Linuxlad 15:34, 13 May 2007 (UTC)

Sulfur hexafluoride (and Xenon too)

Hi, it seems that someone cited a Usenet conversation of yours as a reference in the SF6 article regarding ventilation of the lungs. Since Usenet threads are generally not considered reliable sources, I was wondering if you could provide a better source. Cheers, Itub 11:24, 14 May 2007 (UTC).

• Well, the person citing my conversation wasn't me. As for its content, I've watched heavy liquids and gases mix in lungs by fluoroscopy, and have a good idea of the tremendous power of forced-convective and difussive gas mixing in the normal lung. So I'm certain that the urban myths about Xe or SF6 being so "heavy" they'd have to be actively expelled by bending over (as though they were liquids), are false. Instead, they would simply mix into air very rapidly like normal gases subjected to minimal turbulence (despite the 5:1 wt ratio with air), and once mixed, would stay mixed. I see the same issue has come up in the xenon wiki. All gases are easy to mix, and once mixed, are tremendously hard to separate even by centrifugation and high g forces (as the nuclear guys will tell you) and it's certainly not going to happen much at 1 g. And the mixing forces in normal lung are gigantic and certainly over-adequate, because nature/evolution builds lungs to do that single job, very efficiently.

  There are two ways to handle such an urban myth. The first is simply to delete and ignore it (including deleting the explicit denial of it). The burden of proof is on the myth-asserter. Mythbusting on Wikipedia sets a bad precident, because 1) it's often hard to prove a negative, 2) the myth is often more interesting than the busting of it, so there may exist, for any myth, a long period of time in which it is easier to document the myth-claim via "citable" sources, than to find anybody who's bothered to publish regarding the debunking of it. This is true, even if the myth is an intrinsically ridiculous one which violates what is known of physical law, and sometimes especially so, since the sciences aren't going to bother to debunk some claim about a free energy device, FTL drive, or antigravity machine, which is a billion-to-one going to turn out to be false. I've actually argued elsewhere that this is a fundamental flaw in Wikipedia which gives nutcases an unfair advantage, since they publish crackpot claims more than debunkers bother to publish debunkery. See water fuel cell

  The second option on the xenon and SF6 mixing is to WP:IAR and ask reader to accept a very minimal piece of "OR" reasoning. There are patents (for example see [3]) describing the distribution of hyperpolarized Xe in lungs, which follows a single artifical "breath" of 600 mL of gas in an anesthetized dog, following an induced breathhold induced by a clamped ET tube. Even though this is just one big breath (for a dog) Xe is reported to be distributed uniformly though the lungs (see also [4]), and after a time, the only things that change are the parenchyma where the Xe diffuses into blood and vascular lung tissues, leaving a nice "radiogram" of the large airways, where the initial load is still present because it can't escape by diffusion. Nobody bothers to correct for xenon "collecting" in dependent lung, even after one breath, because they don't need to. But neither do they explicitly deny it doesn't need to be worried about, because it never occurs to them that anything else would be true (moreover, they can see that it's not true, and so can you if you look at the human images). Find me an image of xenon which HAS collected in dependent lung like a liquid! There isn't one! These are respiratory physiologists, and they all know that. Some things are just obvious to them. And if you asked them about SF6 they'd point that it has about the same M.W. as Xe thus should behave in the same way, pretty much putting the kibosh on similar mythology there. If you went to these papers and did a very careful read, you might be able to find some description of the Xe mixing in normal lungs, but I haven't time for it. This kind of thing suffices for ME. Whether it does for Wikipedia or not, I cannot tell. However, remember, I'm not the one using my own comments here to debunk a myth. I was doing that on USENET, in my role as impromtu expert on lung gas physiology. If somebody's needing this kind of thing here, and you think the kind of thing I've just cited demands too much OR reasoning, then feel free to just delete both myth and debunkery, and replace it with the citable ref that a single breath of xenon is distrubted throughout the entire set of both lungs in the anesthetized dog. Cheers. SBHarris 21:24, 14 May 2007 (UTC)

I'm sorry, I should have been more explicit that I didn't think it was likely that you had added that citation. I was also thinking about deleting the whole thing, but I'm afraid it would inevitably reappear. I asked you not because I thought you added it, but because I thought you might have a handy source to quote. I must say that this claim that you must bend over because xenon gets stuck at the bottom of your lungs somehow reminded me of the claim that you can't pee upside down. (Which Richard Feynman says he disproved experimentally! [5].) ;-) --Itub 06:48, 15 May 2007 (UTC)

The best cites I can find at the moment are those above. Perhaps later when I'm not on the road. Benjamin Franklin, as much a genius as Feynman (an even more universal one) found he could releave the obtructive symptoms of his bladder stone by urinating while standing on his head. Clever, eh?SBHarris 15:10, 17 May 2007 (UTC)

Mass not conserved in SR

Steve: I hope you're checking this page. Your revision on Relativistic Mass is out of scope for that page (see new text at the end of that item), not verifiable and not observable. I reverted it. Please reply in this space if you have questions. Thanks. Edgerck 03:48, 9 May 2007 (UTC)

I apologize if I misunderstood you, but I read you think that mass is conserved in SR. You seem to link it to the invariance and conservation of 4-momentum. Can you please clarify? Otherwise, we agree that mass of the system is defined to be the magnitude of the energy-momentum 4-vector and is thus an invariant. Thanks. Edgerck 23:10, 28 May 2007 (UTC)

See your TALK page for my answer. Yes, basically the norm of a system's 4-momentum is its SR mass. And starting from this point helps to define GR mass, too, though that's a harder problem since it involves integration of the stress-energy tensor through a volume.SBHarris 00:07, 29 May 2007 (UTC)

Let me try a question, to see if we can use it to clarify matters. A system has rest mass m. In the lab frame, the system has 3-momentum p. What is the system's mass in the lab frame? Thanks. Edgerck 18:04, 4 June 2007 (UTC)

That's easy: since rest mass is invariant mass (for both single particle and systems at "rest") the invariant mass is m. Since invariant mass is both conserved and invariant, the mass (invariant mass) of the system will be m in ANY frame, including the lab frame where it has more momentum and energy than it has in its "rest" frame. But remember, when you say the system has "rest mass m" you must refer to the length of its 4-vector. This system rest mass will be its E/c^2 in the COM frame (not the lab frame) and will not in general be the sum of the rest masses of the system's constituents (unless they are all not moving with respect to each other, and exert no forces on each other).

m^2 = m^2 (COM frame = rest frame). System rest mass = invariant mass

E^2 = m^2 (system rest energy)

m^2 = E'^2 - p^2 (system mass in lab still invariant). System E in this frame is E'

E'^2 = m^2 + p^2 = E^2 + p^2 (system energy in lab frame)

SBHarris 20:17, 4 June 2007 (UTC)

Yes, notwithstanding the system's 3-momentum in the the lab frame, the system mass in the lab frame will be the same as the system mass in any inertial frame. This result is valid for any system, not just for particles. This result also applies to the atom+photon system, which system has mass m given by m² = E² - e² in the inertial frame where the atom is at rest, and in any inertial frame. Thanks. Edgerck 21:51, 4 June 2007 (UTC)

Inertial frame where the atom is at rest WHEN?? SBHarris 01:45, 6 June 2007 (UTC)

After the photon is emitted, as stated. I'll ignore the LONGER REPLY below, as you do not calculate the mass in the inertial frame where the atom is at rest and, thus, do not reply to my result. Thank you. Edgerck 16:35, 6 June 2007 (UTC)

You didn't specify whether or not it was a free atom. After Count Iblis gave you the full treatment for that case (see his proof), you proceeded to claim that mass wasn't conserved for this system even in a Mossbauer experiment, where the atom doesn't move in recoil. So I gave you the proof that invariant mass is conserved there also. You now have proof for both cases. What is it that you want? SBHarris 20:48, 6 June 2007 (UTC)

---

LONGER REPLY

In a word, no. Let's do what Count Iblis didn't do below, because you didn't (at first) bring up the case where the atom is pinned down by a crystal latice, in a Mössbauer spectroscopy experiment. So let's do that one. It's like doing an energy and momentum conservation experiment with a rifle, where the rifle is put butt-down on the ground, so what "recoils" is the whole Earth. It recoils, but not enough to see or measure. This lets us stay in the lab frame all the time, with the rifle and atom, which has no recoil velocity, and thus stays in its initial lab frame (to all approximation). However, the atom still absorbs the recoil momentum of the photon, in the same way the earth absorbs the bullet momentum when you put a rifle against the ground and fire straight up. The earth STILL gets the bullet's full momentum, but (essentially) none of the reaction energy, and its recoil velocity (to any approximation) is zero.

Let us (now) call the mass of the atom before emission M and after emission, M_a. Atom energy before emission is M/c^2 = E_i and after emission is M_a^2/c^2 = E_a. The photon energy, we'll call e. Momentum of the photon is thus e/c, and momentum of absorbed by the atom is e/c, even though it doesn't move out of our frame (just like the Earth and the rifle). There is no frame-shifting here, as we always stay in the atom's frame, which is the lab frame, and (to an approximation good enough that we can't see the difference) also the COM frame, since (again) the atom is tacked down and has no recoil velocity. This all greatly simplifies the problem. Count Iblis has worked out the general case with a recoil atom velocity and need to define frames as lab, atom, etc. I will do the Mössbauer spectroscopy case where none of these change and all are the same, which you claim still proves your point. Actually, it does not.

System mass I'll call m. I'm going to work in units of c=1 where M_a = E_a and e/c = e, and so on.

Before emission:

m^2 = E_i^2 = M_i^2 so m = M_i

Thus, the invariant mass is the mass of the atom before emission, and m = M_i = E_i. The invariant mass is also the atom's total relativistic energy before emission.

After emission, the invariant mass of the system m^2 (the same in any frame) is given by summing up the total relativistic energies of atom and photon, and their momenta. The photon has energy e and momentum e = p_photon.

m^2 = (E_a + e)^2 - (p_atom + p_photon)^2

Now, because we remain in the COM frame with atom tacked down, p_atom = p_photon, by conservation of momentum, which holds because the observer remains in the lab frame, which is also the COM frame AND the atom frame (in this special case). The atom, as part of a system, gets the momentum without getting any velocity which we need to worry about. So we can STAY in the atom frame, which is also the COM frame which is also the lab frame, and thus we have conservation of 3-momentum and relativistic energy. We can't do any of this easily if we let the atom free. However, it's all legitimate if we tack it down. Thus:

m^2 = (E_a + e)^2

You can see what's going to happen. Because we have no need to shift frames and can remain in the lab/COM/atom frame all the time, energy is conserved for us, and E_i is thus E_a + e. So E_a = E_i - e by conservation of relativistic energy in our frame(s), which are all one and don't change.

m^2 = (E_i - e + e)^2 = E_i^2

So m = E_i = M_i after photon emission, too.

That's it. Invariant mass is calculated by simply summing relativistic energies of all products before and after emission in this sytem, because we're in the COM frame where the momenta cancel. And since relativistic energy is conserved so long as we don't change frames (which we didn't), invariant mass is also conserved automatically and neatly in the COM frame, along with the relativistic energy (and relativistic mass). Invariant system mass is actually conserved in all frames, but this frame (the COM frame) is the easiest to show this conservation. And since it's the same frame as the lab and atom frame for this particular problem, you should have no problem seeing that it's conserved in all frames of interest in a Mossbauer experiment. The stuff you're talking about below, involves letting the atom recoil, and Count Iblis has done that general problem correctly, and pointed out where you slipped in your own math, already. SBHarris 04:22, 5 June 2007 (UTC)

---

(lifted quote, out of context, follows, regarding a different experiment where the atom is allowed to recoil)

Edgerk: "Just in case you didn't read the reply on the "mass in special relativity" talk page":

Quoting Count Iblis

About the kinetic energy, note the Edgerck wrote above (in the invitation to fair discussion section) :

"Using m for the mass of the system atom+photon in the atom's rest frame, m² = [(M - e) + e]² - e², where M is the atom mass before the photon is emitted and e is the photon energy (also its momentum), in c=1 units. The result is m² = M² - e². The mass of the atom+photon system is less than the atom mass before emission. Mass is not conserved in a closed system.Edgerck 13:55, 30 May 2007 (UTC)"

So, Edgerck is reasoning like this. M is the (invariant) mass of the excited atom. He subtracts the photon energy e from M where e is measured in the rest frame of the ground state atom) to obtain the mass of the ground state atom. This is, of course, not correct. He then takes the four momentum of the atom after it has emitted the photon to be (M-e,0), because in the atom is at rest. The photon has a four-momentum of (e,e). The total four momentum is then (M-e+e,e)=(M,e). And this then leads to the false conclusion that m^2 = M^2 - e^2.

So, the source of this mistake was to take e to be the difference of the two rest masses, while it should be taken to be equal to the difference in total energy. So, the error is just the kinetic energy that he ignored. Now, this is indeed small, but so is the effect he claimes:

m^2 = M^2 - e^2 --->

m = sqrt[M^2 - e^2] = M sqrt[1-e^2/M^2] = approximately

M[1-1/2e^2/M^2] = M - 1/2 e^2/M

So, Edgerck is saying: I ignored the kinetic energy because the kinetic energ due to recoil is small. Fair enough, but then he claimes that m is less than M. He didn't say by how much. As you can see it is less than M by an amount 1/2 e^2/M. Now e is the momentum of the photon (in c = 1 units), so this is just the kinetic energy of the atom he ignored.  :)

Count Iblis 22:04, 4 June 2007 (UTC)

Breaking News: Edgerck has finally revealed the error he is making!

see here.

You and I had already concluded that he was making some sort of mistake. I'm not sure if you had already pinned down exactly what error he was making. Time after time again he would say that the mass of a closed system can change, but when discussing concretre examples there was never a disagreement. So, I thought that he was taking the mass to be the sum of the rest masses of the particles in the system. But just now he has revealed the error, see above link. :) Count Iblis 23:35, 28 May 2007 (UTC)

Suggestions?

My suggestion is to have him banned. He's not behaving as a Wikipedian, cooperating to build consensus, taking breaks from contentious areas. He's claimed his "domain" and he's going to lord over it and clutch to it until something prevents him from doing so. Robert K S 23:05, 11 June 2007 (UTC)

Okay, your vote's in. For the record, I agree. But not a permaban. Perhaps something like a ban from editing energy related articles for a year. SBHarris 23:07, 11 June 2007 (UTC)

I don't know exactly how bans work, but it is only reasonable that the minimum necessary action be taken. Robert K S 23:13, 11 June 2007 (UTC)

Yes, I completely agree. I'll give him a few warning shots over the next week, suggesting that he cooperate, rather than disrupt the process. If he continues with his actions, I'll support what needs to be done. Sorry, I havn't been watching this page, I have been busy lately. If had seen this happening, I would have stopped it a long time ago. Talk soon: --Sadi Carnot 23:51, 11 June 2007 (UTC)

Me too! --Itub 07:12, 12 June 2007 (UTC)

Anyway, you've way underestimated the proportion of his edits spent on energy-related articles. Other articles he's spent time on are chemical substance and, curiously, anger and anger management. He also seems hung up on defining topics as and getting them classified as "concepts" (or, as he spells it, "cocepts"). Apparently he's curious about his editing stats, since he's asked how he can find them out. (The reply merely provided the two links I already gave him.) Robert K S 09:08, 18 June 2007 (UTC)

Yeah, I never thought to total up all the energy related article edits. Just the ones on energy alone are enough to make the case. I can well believe he needs help with anger management, as I imagine his behavior would be expected to cause continual angry backlashes whereever he is and whatever it is he does (I gather he's a science writer! Or claims to be). Anyway, I know we've been blunt with him, but that's the only way to get some people's attention. Goodness knows we've tried everything else. SBHarris 10:27, 18 June 2007 (UTC)

Your bet on WT:BLP

You're on. And if you turn out to be right, I will certainly admit so. But I don't believe you will be, not so long as the office still takes care of well-founded complaints quickly and definitively. Seraphimblade ^{Talk to me} 14:24, 26 June 2007 (UTC)

But the failure of OFFICE (which is overworked and way behind right now) is part of the deal. It's an inevitable and expected part of the process. But hey, it's your face. SBHarris 18:06, 26 June 2007 (UTC)

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