Wikipedia:Reference desk/Archives/Science/2023 November 6

= November 6 =

Wien's displacement law by energy density and not power ?
Why in Wien's displacement law on a graph we have the ordinate in energy density and not in power per square meter, when it is this power which is measured in the black body experiment? Malypaet (talk) 18:29, 6 November 2023 (UTC)


 * Blackbody radiation.svg article on Wien's displacement law is not concerned with the experimental methods with which black-body radiation curves may be obtained and the wavelength at which the curve peaks does not depend on whether one measures energy or power, so for the purpose of illustrating the law this is immaterial. That said, I agree that using energy (with an undefined time interval) in the graph is indeed strange. We could replace the image by the one on the right. Its abscissa has no graduation, but for the purpose of illustrating the law this is also immaterial. --Lambiam 09:33, 7 November 2023 (UTC)
 * Sorry, but this law is validated by experiment of black body radiation. For example put the black body temperature by step between 1 to 100, on each step with 100 different filter giving power for a Δλ with λ varying between 1 to 100, then you deduce the Wien's displacement law. Physics is experiment, not immaterial which is in the domaine of science fiction.
 * So can you explain me how you can measure radiation energy without deducing it from radiation power measurement ? Kirchoff law and stephan-boltzmann law are expressed in power, right ? Malypaet (talk) 12:50, 7 November 2023 (UTC)
 * Finaly I find this with Power, and it is clear for me, its physics :Spectral radiance output of black-body object at various temperatures versus wavelength. Position of radiation maxima plotted in black dotted line Malypaet (talk) 23:30, 7 November 2023 (UTC)
 * Pressure is measured by measuring a force. So should all graphs having pressure on the y-axis be replaced by graphs with force on their y-axis? Of course not; one is allowed to use computed quantities in graphs. Also, one can draw graphs for laws of a theory, which give continuous curves and are in no way restricted by how the quantities validating the law were experimentally obtained. If we were restricted to graphs of data obtained by measurement, we'd only see data points with error bars and best-fit curves. --Lambiam 08:06, 8 November 2023 (UTC)
 * Have you take à look at my Graph ? Its the same Graph, but ordinate corresponding To the measurement, so what was in nature. Kirchoff and Stephan-Boltzmann law also use power, not energy density. Malypaet (talk) 12:55, 9 November 2023 (UTC)
 * The top image in our article shows energy per volume per wavelength. It's talking about a radiation field. Don't think about a flat plate emitting radiation; think of the inside of a hot oven with radiation going in every direction. It's not an amount of energy accumulated over some time; it's the energy instantaneously present in the radiation in some volume. PiusImpavidus (talk) 15:42, 8 November 2023 (UTC)
 * "instantaneously", I like this Word, in computing science one use memory snapshot to look what was in process context, you stop the time to have troubleshooting time. But nature, so physics, does'nt exist without time. I understand the concept of energy density, but here we obtain the same graphs with the power which is measured, and it is the power which represents the temporal nature, so it is this which we should find in the graphs. Otherwise we take the risk of entering an imaginary mathematical world. Malypaet (talk) 13:08, 9 November 2023 (UTC)
 * You tend to keep objecting while ignoring the explanations provided to you. That is not productive. --Lambiam 21:52, 9 November 2023 (UTC)
 * I'm not ignoring the explanations, they are simply off topic. When measurements are in power per square meter, which can be translated into energy density and this gives the same graphs, why publish the graph in energy density? There must be a reason and that's what I'd like to know. Malypaet (talk) 22:28, 10 November 2023 (UTC)
 * Because, as was explained above, there is no reason to tie the presentation of laws to the empirical methods that led to the data that led to the laws, just as we are also not obliged to present them in the language in which they were originally formulated. --Lambiam 09:41, 11 November 2023 (UTC)
 * That's a negative answer like "I don't know". On wikipedia: "Formally, the wavelength version of Wien's displacement law states that the spectral radiance of black-body radiation per unit wavelength, peaks at the wavelength... ". Spectral radiance is in Watts. So Apparently I shall not get my answer here: Why it is preferable to present the graph in energy density ? Because it is easier to compare with perfect gaz energy density, or because... Malypaet (talk) 13:23, 11 November 2023 (UTC)

How can you tell if a restaurant's hotdogs have nitrites in them?
Without directly asking the restaurant staff if their hotdogs have them? So there's nitrates and nitrites, nitrites are actually worse and unhealthier than nitrates, but nitrates can be converted into nitrites. Is it possible to know by a restaurants cooking methods whether hotdogs will contain them? I note that for most cases, they just pull hotdogs out of a hot water bath, so it is very quick. Burgers take longer because they cook them. But does soaking hotdogs in a hot water container, actually help pull out nitrites from the hotdog? Then it's a question of how often is the water changed? Thanks. 170.76.231.162 (talk) 19:06, 6 November 2023 (UTC).
 * I wouldn't count on the restaurant staff knowing. But why don't you try asking them? ←Baseball Bugs What's up, Doc? carrots→ 19:45, 6 November 2023 (UTC)
 * First time I've ever seen the words "restaurant" and "hotdog" in the same sentence. The things you read. -- Jack of Oz   [pleasantries]  20:42, 6 November 2023 (UTC)
 * See List of hot dog restaurants. ←Baseball Bugs What's up, Doc? carrots→ 22:16, 6 November 2023 (UTC)
 * Ah yes, fast-food restaurants. But from what I gather, grocery store hotdogs all contain nitrites in them as preservatives. Restaurants don't buy hotdogs from grocery stores, they likely buy from restaurant distribution centers, but I imagine it's still the same. And I'm guessing you don't put nitrites on hotdogs right before you're going to cook them, which means, all restaurants buy hotdogs that already contain nitrites in them? It's just a matter of removal? Is there such a thing as organic hotdogs? 170.76.231.162 (talk) 21:02, 6 November 2023 (UTC)
 * Maybe if the hogs were raised organically. Or maybe if they're vegan hot dogs? ←Baseball Bugs What's up, Doc? carrots→ 22:16, 6 November 2023 (UTC)
 * Gosh! I thought to myself 'organic hotdog, I gotta see this'. So I looked it up and yes the first return from Google had 'Welcome to our range of pure beef Frankfurters – artisan, hot-smoked sausages, made from finely chopped beef and free from artificial additives, emulsifiers or preservatives.' So it definitely is possible okay! NadVolum (talk) 22:39, 6 November 2023 (UTC)
 * Look at the colour of the meat. If it is pink, then nitrites would be there. Graeme Bartlett (talk) 21:18, 6 November 2023 (UTC)
 * Is the difference in hue/ tone as compared to ones without nitrites (prepared of course, not raw) that pronounced that it would be noticeable? --Ouro (blah blah) 10:25, 7 November 2023 (UTC)
 * Yes, that's basically why they put the nitrites in there, otherwise the sausages would be gray (see Nitrite). Abductive  (reasoning) 06:56, 8 November 2023 (UTC)
 * Even if it was, you'd need a similarly composed hot dog without nitrites to serve as the control and, if you had that, you could just eat the control hot dog. Either way, we're dealing with extremely processed foods here and there may well be colouring agents added on top of whatever the nitrites are doing. Matt Deres (talk) 20:16, 7 November 2023 (UTC)
 * Isn't the color of the meat more dependent on how hot you cook it and how long? But that's if it were a steak, aren't hotdogs just soaked in hot water? Aren't nitrites put on the surface of hotdogs, not inside? 170.76.231.162 (talk) 18:41, 8 November 2023 (UTC).
 * Hot dogs, even though cured, must be cooked to be safe for consumption, mainly because of the risk of raw hot dogs being comtaminated with Listeria monocytogenes. Commercially produced hot dogs are cooked during the production process, just long and hot enough to ensure protein denaturation. The soaking in hot water merely serves to heat already cooked sausages. Unless the temperature reaches at least 165 F it will not cook raw sausages but may in fact even increase the health risk. The pinkness of the filling comes from the curing. Instead of (or next to) nitrites, other curing agents may be used, while other additives may enhance redness. --Lambiam 22:41, 9 November 2023 (UTC)
 * Also precooked hot dogs may, reportedly, be contaminated and should be re-cooked. --Lambiam 22:54, 9 November 2023 (UTC)
 * I mean, you could learn analytical chemistry and do it yourself.... --Trovatore (talk) 23:17, 7 November 2023 (UTC)
 * What instrumentation could detect inorganic nitrites? Not GC or HPLC since this is presumably a solid. Flame AA is for elemental. So UV-vis? 170.76.231.162 (talk) 18:40, 8 November 2023 (UTC).
 * I had in mind more wet chemistry. Not that I'd know how to actually do it.  Lab equipment and I never really got along. --Trovatore (talk) 18:56, 8 November 2023 (UTC)
 * Hmm, nitrites aren't an acid or a base, but it might be an oxidizer, can wet chemistry detect for that? 170.76.231.162 (talk) 19:03, 8 November 2023 (UTC).
 * I'm confident it can be done. I never claimed to know how.  That's why I said "learn". --Trovatore (talk) 19:12, 8 November 2023 (UTC)
 * It would be nice if editors commenting at the Help Desks would anchor themselves in the real world. I live on the outskirts of Grass Valley, California, a rural Sierra foothills town of about 13,000 people, not including its suburbs. I can easily find a variety of nitrite free hotdogs by meat packers like Nathan's Famous and Oscar Mayer and Hebrew National and several local brands. They are not grey and do not have different coloration but, in my opinion. their flavor is a bit bland. Cullen328 (talk) 07:56, 8 November 2023 (UTC)
 * They don't have test tubes in Grass Valley? --Trovatore (talk) 17:13, 8 November 2023 (UTC)
 * The real world, Cullen? Good grief, most of us hang around here in order to escape from that horrible place. -- Jack of Oz   [pleasantries]  19:42, 8 November 2023 (UTC)
 * I live in a town of about 50.000 mid way between Poznań and Wrocław in Poland. Given the number and variety of grocery stores per 1000 inhabitants has risen sharply recently, I believe it would also not be a problem to find nitrite-free hot-dogs, heck, I bet the small-time bakery in my building has'em. The cheaper, the more sodium nitrite, usually. --Ouro (blah blah) 10:06, 8 November 2023 (UTC)
 * It should be noted that due to historical curiosities in US labeling laws, products that contain nitrites derived from certain sources such as celery powder can be labeled as "no nitrites or nitrates added", even though they may contain as much or more added nitrites as other products which cannot be so labeled. CodeTalker (talk) 01:29, 10 November 2023 (UTC)