Historical Definition and 92 Threads

When watchiig historical shows, I often find myself musing about how I might survive in those times - from a time traveler point of view. ie. I appear with only my own current 21st century layperson's knowledge. Can I substantially improve the livelihood and survival rate of the community I find...

I just received a slap over my fingers with a good old-fashioned slide-rule. Officially for an off-topic post but, in reality for falling victim to the Dunning-Kruger Effect. Thus I hope I don't overstep any unmarked lines here when I offer a historical view of one of my pet peeves in relation...

Hello, I've heard versions of these statements (below) from other scientists, but I've never seen anyone break them down. Do molecules in air really move (diffuse?) their way around the entire globe, or are there localized "pockets" that really don't move that far from home? Intuitively, water...

Hello all: Watching few news , titanic came and we start to have a question , can I prove that titanic was sunk because of hitting an ice mountain, and not because of torpedo, should we use material specifications , speed of the ship , and material specifications of the ice mountain or we...

So, if I get it right, the basic argument goes like this: AC was preferred to DC because its voltage can be stepped up by a transformer. This limits losses while the current is transported from the production plant to the final user. The voltage is subsequently stepped down when delivered to the...

Hi, I believe that I have an acceptable level of understanding where SRT, GRT, QM and QFT come from. This is not true for me regarding the "good old stuff". Newton, okay, this is relatively (:wink:) clear to me but do you know something about the historical motivation for Lagrangian and...

I've been thinking about the German Enigma machine, and how it might have been analyzed in a more modern perspective, without using attacks using known (or guessed) plaintext. My understanding how the Engima worked is as follows: there are 3 (sometimes 4) rotars, each with 26 letters A-Z marked...

I am new to the field of climate change. Are there publicly available simulation code for Earth's temperature history, going back, say 2000 years, with a resolution on the order of years? Thank you very much.

I was wondering if anyone knew of sources regarding the history of Dedekind Cuts and its use to construct the Reals. Ie., the mathematical thinking leading to this idea, why it is important, and how it allowed to put Analysis on a rigorous foundation.

As much as i search Google, in an effort to find out how exactly the constancy of speed of light was historically deduced before 1905, from Maxwell equations or by any other means, i am not able to find such an explanation. In all of the search results that i could find, it is just stated that...

My son and i were discussing aerodynamics and he brought up a paper from https://phys.org/news/2012-01-wings.html It seems that the latest discussions seem to completely discount the differential velocity of air flow as a cause of differential pressure, but point to a differential pressure...

Hi all. I'll get to the point. I've been interested in electricity since I was in college. Concepts such as current and resistance seemed easy to grasp for me but voltage remains a little bit obscure. It's thanks to this forum (specially forum members Jim Hardy r.i.p and SophieCentaur, sorry if...

This is about the history of electromagnetism. I already know about the convention that defined which electric charge is the "positive" one, which ended up making the electron a negative particle. But what about the "positive" direction of the magnetic field? Does anybody here know how it was...

Photo: Tomb of Ramses VI. Beautiful scrollable panoramas (360) on 360cities: Temple of Isis Tomb of Ramses III Temple of Horus Al Dier Monastery at Petra More panoramas: Mohamed Attef, panoramic photographer. Other panoramas: Ramses VI panorama (360) on facebook. A video showing the tomb of...

What is the history of the concept that a measurement process is associated with a linear opeartor? Did it come from something in classical physics? Taking the expected value of a random variable is a linear operator - is that part of the story?

I have Abstract Algebra Course, and my teacher is using the book, "Abstract Algebra" of David S. Dummit, and Richard M.Foote. This book, and other books which my teachers are using for the courses, seem to give definitions, theorems, and problems, in no historical order or are not mentioning the...

Sometimes experimental or observational evidence from credible physicists points to new physics and then turns out to be wrong due to statistical flukes, experimental error or a theoretical analysis mistake. What cases of this happening do you find most notable, what showed that the hints were...

At high school, we saw without demonstration the fundamental principle of dynamics (2th Newton's law), i.e : $$\sum \vec{F}=m \vec{a}\,\,\,\,\,\,\,\,\,eq(1)$$ after, at university, we saw another expression of this 2th Newton's law : $$\sum \vec{F}= \dfrac{d\vec{p}}{dt}\,\,\,\,\...

I'm wondering if anyone knows where I could find information on historical costs and efficiencies of various sources of energy (hydroelectricity, coal, petroleum, natural gas, etc.) and plant types (steam, diesel, and gas turbine), especially at facilities of various sizes. That information...

I don't see why imaginary numbers were necessarily so difficult among top mathematicians back then. From pleano's axioms, we can derive the fact that any negative natural number times another negative natural number must be positive. Then this result extends to the reals, using theorems derived...

Hi. There were theoretical (find transformations under which Maxwell's equations remain invariant) and experimental (speed of light is constant, Michelson-Morley) indications that made the development of SR inevitable. But what about GR? Was there a "need" for this theory or was Einstein just...

This won't be news to the lovely PFers who happen to be Brits or Commonwealth citizens. But this floored me - I guess I'd never really thought about it: Several hundred years from now, people might not think of the latter part of the 20th century as the Cold War Era, or the Post-WW2 Era, or...

Hey guys, nice to meet you all! My name is Jonathan and I'm from Queensland Australia. I'm currently working on a project which is seeking to find the most accurate method to value an asset based on historical stats. I think the best way to describe would be to provide a theoretical example: I...

Late last year, I started a thread (https://www.physicsforums.com/threads/historical-paper-dump-sites.780669/#post-4907513) to solicit/compile a list of URLs with open access to historical papers; shortly after, I discovered that several of them weren't as open as they had been...This morning, I...

I am currently starting an education in physics and want to have a career in this field as well. My question concerns today's attitude toward each other within the community regarding new ideas and concepts. I consider myself to be a very creative person, perhaps more so then a love for...

I'm looking for sites with historical journal articles -- ideally in English, but if there's none available, I can settle for the original. Specifically, I'm looking for stuff by (in no particular order, and certainly not exclusively) e.g. Heisenberg, Pauli, Dirac, Schrodinger, Feynman...

In my studies, I find myself coming back to the same question.How do we know all these things about matter. Its quantized, it has mass and, charge and blah blah blah. I understand that these models of the building blocks of "physical things" are well tested mathematical models that attempt to...

So, I have an idea to write a (sort of) "time travel" story in which future historians are able to transport a non-intrusive (possibly mass-less) viewport to various important events in history (and then accidentally incinerate Mohenjo-Daro with this technology, thus explaining certain Vedic...

I've got a term paper due in a couple of weeks and I need to find a historical physicist to write it about. The paper will highlight his/her's contributions to physics and will be a bit on the technical side (including equations, maybe some derivations and proofs). I was wondering if anyone had...

Hello everyone, I am not a physicist (I'm an economist), but I'm interested in physics. What I'm particularly interested in is what the empirical and theoretical/mathematical junctures were in the development of our understanding of physics. What were the empirical observations that motivated...

I am reading a chemistry book printed in 1805. The chemical reaction equations are written using the equality symbol = instead of the arrow →, which is used in modern times. Anyway sometimes it is still possible to see the "old fashioned" way...

Is there a physicist who has discovered this, and could you explain how he/she did it or give me? Yes I know, I have asked almost the same question, but I need both of them. thank you

Is there a physicist who has discovered this, and could you explain how he/she did it? I was trying to find it on the internet, but it only gives me a lab review of load vs efficiency. thank you

Homework Statement Share market trading calculator. I have tried to write code to calculate the buy and sell with profit/loss on historical data using moving averages. I'm am not interested in leverage yet. bank = 10000 equity = 10000 sell = is current price of an instrument on the...

I'm developing a collection of historical papers that students of cosmology would find handy for essays etc . Any links to such papers would be great. Preference on original reprints where possible Here is what I have located thus far. Any papers must be allowed for distribution without...

incident question -- historical event with lack of ethics I have to Write a report outlining an historical event in which a lack of ethics has caused the injury or loss of life. You should discuss the issues with reference to the Engineers Australia code of ethics. i can't find any events...

Hello, Analytic geometry has provided us with such profound tools for thinking that it is hard to imagine what thinking must have been like before we had such tools. Two particular developers of these tools are Pierre de Fermat and Renee Descartes in 17th century France. I would like to...

What would that be, and most importantly why? I have a couple that are probably counter-intuitive, but reflect my view of things. 1. Delete christianity 2. Delete Caesar Any one of those two would be fine with me. All in the benefit of science ofc. In any case justifications below.

Is there anyone here who could help me understand the state of physicists understanding just prior to 1905 and Einstein's SR paper? I keep running into length contraction, considerations of simultaneity and its non-universal nature, Lorentz transformations, time dilation and other concepts that...

This would go nicely in the Philosophy subforum, but I seem to have arrived just in time to see that being closed. So I guess it goes under General Discussion. This is not quite a "philosophy of science" question, but more a history of science question anyway. There seem to be plenty of...

Is it possible to calculate the historical whereabouts of the asteroid belt, as it seems to be moving ever outward due to the radiometer effect? Can it be calculated, for instance, where it was 1,000 years ago? 100,000 years ago? Etc. In particular, I'm curious as to whether the science is...

Hi, Earlier this month, I was searching for trends/graphs on solar activity. I found some good sites which I cannot post due to me being a forum noob ;-) Now, I am looking for the equivalent except this time, in relation to earth's magnetosphere levels (strength) Does this exist ? Thanks, Danny

Hello! I'd like to know when the high density of the atmosphere of Venus was first determined or suspected. Was it with the Russian probes that the first evidence came that the atmosphere was much more dense than the Earth's? Or had there been other indications earlier in time that such was...

The French physicist http://www.encyclopedia.com/topic/Pierre_Maurice_Marie_Duhem.aspx#1 wrote:The legitimate, sure and fruitful method of preparing a student to receive a physical hypothesis is the historical method. To retrace the transformations through which the empirical matter accrued...

I have just had a short discussion with somebody online about how some scientific terms are hugely misleading due to some historical misunderstanding. The example that I put forward was the term 'planetary nebula', which was originally given to objects that looked like planets in poor quality...

Why is it that history and all the way to this present day, people have noticed the flaws of elders before them.. yet nothing has changed? Is the study of these flaws just lacking? why is the history repeating it'self chain happening so often to events of many kinds and varieties?

I apologize for the rather vague title. It's space-limited and I'm not sure how to concisely state what I want to know. Basically, I understand that the solutions to quadratic equations (and if I remember correctly cubic equations) often had surveying problems land surveying. However, quartic...

Hey, in general relativity, essentially I am asking how any metric (I.e. schwarzschild metric) was found. are the metrics derived or are they extrapolated from the correct lagrange equations of motion? If there is a derivation available, please provide a link. thanks

If you went back in time and brought with you modern day devices, could you teach the people of that day (to a certain extent) how to create and use these devices? What impact would this have the modern day? Would we be more evolved?

I am interested in learning math from a historical perspective. Starting with euclid and working myself up to descartes. I am thinking of a reading list to use and this is what I think I will use. I have taken math classes all the way up to calc 2 so I am not an expert and I am doing this just...