# What is sir: Definition and 33 Discussions

Sir is a formal honorific address in English for men, derived from Sire in the High Middle Ages. Both are derived from the old French "Sieur" (Lord), brought to England by the French-speaking Normans, and which now exist in French only as part of "Monsieur", with the equivalent "My Lord" in English. Traditionally, as governed by law and custom, Sir is used for men who are knights and belong to certain orders of chivalry, as well as later applied to baronets and other offices. As the female equivalent for knighthood is damehood, the suo jure female equivalent term is typically Dame. The wife of a knight or baronet tends to be addressed as Lady, although a few exceptions and interchanges of these uses exist.
Additionally, since the late modern period, Sir has been used as a respectful way to address a man of superior social status or military rank. Equivalent terms of address for women are Madam (shortened to Ma'am), in addition to social honorifics such as Mrs, Ms or Miss.

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1. ### Mathematica Trying to model red and grey squirrels

ClearAll["Global`*"] (*R = reds, G = greys*) (*S = susceptible, I = infected, R = recovered*) tseries = {t, 0, 3}; vars = {HG[t], HR[t], SG[t], IG[t], RG[t], SR[t], IR[t], aG[t], qG[t]}; b = 0.4; (*natural mortality rate, both species*) \[Beta] = 0.7; (*rate of virus transmission*) aR =...
2. ### Sir Brian Harold: Queen's Guitarist & Astrophysicist Honored with Knighthood

Brian May lead guitarist and co-founder of Queen who earned a Ph.D. in astrophysics was knighted for his services to music and charity (animal welfare). https://americansongwriter.com/queens-brian-may-becomes-sir-brian-harold-with-knighthood-honor/
3. ### Sir Isaac Newton exam question

I thought about using the snell’s law because it involves different refractive index but I have no idea why the wavelength would be affected by the snell’s law. I thought that maybe if I found the frequency I might be able to get the wavelength but, I don’t know which formula I should use. I...
4. ### "Sir" Knighthood in Cricket -- Should we add "Madam" for Women Cricketers who have excelled?

"Sir" Knighthood in Cricket. Do you feel Similar to "Sir" Knighthood in Cricket, there can be conferred "Madam" for Women Cricketers who have excelled?
5. ### R.I.P. Sir Thomas Sean Connery

Sean Connery has left us at the age of 90: https://en.wikipedia.org/wiki/Sean_Connery https://www.imdb.com/name/nm0000125/bio?ref_=nm_ov_bio_sm
6. ### Who Were Sir Isaac Newton's Rivals in the Scientific World?

Other than Robert Hooke, Gottfried Wilhelm Leibniz and John Flamsteed, did the great astronomer, mathematician, physicist, philosopher and theologician, Isaac Newton have any rivals. He is "eminent" for having a great number of opponents, presumably due to his all-round polymathic intellectual...
7. ### News RIP James Bond actor Sir Roger Moore

I just saw this on my personal Twitter feed, as well as the following BBC article. I greatly enjoyed Roger Moore both in old episodes of The Saint, as well as his turn as 007. My condolences to his friends & family. http://www.bbc.com/news/entertainment-arts-40018422
8. ### MHB Solving SIR Model with Euler's Method

Question on SIR Model and using Eulers method for approximating a solution. Given the 3 ODEs of the SIR model dS/dt = -\betaSI dI/dt= -\betaSI - \gammaI dR/dt = \gammaI Ive been asked to produce in excel Eulers method for axproximate solutions. Given some initial values for S(0) and I(0) as...
9. ### B How were differential equations for SIR Models calculated?

Specifically:
10. ### Happy 85th Birthday, Sir Roger Penrose

Roger Penrose, of course, needs no introduction. At 85 he is as productive as ever, publishing papers, giving guest lectures. He also has a new book on the way and a kid currently in primary school. Here is a somewhat recent interview detailing a few aspects of his life. Happy birthday to you...
11. ### News The late Prof Sir Tom Kibble awarded Isaac Newton medal

http://www.bbc.co.uk/news/science-environment-36675894 On a personal note, he was very kind and encouraging when I spoke to him about some of my unconventional ideas about physics when I was a student (on the Computing Science course) at Imperial College in the 1970s.
12. ### News RIP Sir David Mackay: Physicist, Mathematician, Author

Hi everyone. I'm not sure if anyone from here on PF is familiar with Sir David Mackay, but he was a physicist and mathematician known for his contributions in information theory and machine learning, as well as serving as Chief Scientific Advisor of the Department of Energy and Climate Change in...
13. ### Sir Roger Penrose´s contributions

I was trying to make a full list of the contributions of Sir Roger Penrose. What is missing? 1)Twistor Theory 2)Penrose Tilings 3)Penrose Triangles and stairs 4)OrchOR 5)Conformal Cyclic Cosmology 6)Tensors, geometry, and topology 7)Gravitational Wave 8)Penrose Interpretation 9)Penrose...
14. ### Sir Roger Penrose: Challenging Modern Physics Theories

http://www.sciencefriday.com/segment/04/04/2014/sir-roger-penrose-cosmic-inflation-is-fantasy.html What does Sir Roger know that others do not. Sir Roger Penrose calls string theory a "fashion," quantum mechanics "faith," and cosmic inflation a "fantasy." Coming from an armchair theorist...
15. ### Sir Patrick Moore dies aged 89

http://www.bbc.co.uk/news/uk-20657939 R.I.P.
16. ### Sir Lost-a-Lot castle bridge

Homework Statement Sir Lost-a-Lot dons his armor and sets out from the castle on his trusty steed in his quest to improve communication between damsels and dragons. Unfortunately his squire lowered the draw bridge too far and finally stopped it 20.0° below the horizontal. Lost-a-Lot and his...
17. ### Source Impedace Ratio (SIR)

I would like to get opinions when calculating Source Impedance Ratio (SIR) on a Power System. Usually when calculating a three Phase fault it only takes into account positive sequence components, obtaining the source impedance ratio via the ratio of the source positive sequence component...
18. ### Sir Isaac Newton Contest Question (Energy)

Hey This problem has been stumping me for awhile and I just don't seem able to get it Homework Statement A space shuttle lands ona distant planet where the gravitiational acceleration is 2.0 (We don't know the local units of length and timem but they are consistent throughout this...
19. ### Sir Author Eddington and Einstein's GTR

Hello, I have a question or two about Sir Author Eddington's proof of Einstein's GTR. 1)How did or what technique did Sir Eddington use to know where to get the best photo of the eclipse. 2)Can someone explain the experimental technique behind his proof of Einstein's GTRMany thanks from a...
20. ### Sir William Blake’s Auguries of Innocence

I just read Sir William Blake’s Auguries of Innocence. Reading it, I’ve been left in a quandary. It brings to light some of my own doubts about ourselves. We as a people, no, civilization, no not even that, something more than a civilization, more essential, the building blocks of civilization...
21. ### Sir Isaac Newton contest solutions 2007

Sorry if I posted in the wrong place. Does anyone know where to get the Sir Isaac Newton contest solutions 2007? The site has solutions for 2008, but not of previous years. Thanks.
22. ### Sir Lancelot Equilibrium Bridge Problem

Homework Statement Sir Lancelot rides slowly out of the castle at Camelot and onto the 12.0-m-long drawbridge that passes over the moat. Unbeknownst to him, his enemies have partially severed the vertical cable holding up the front end of the bridge so that it will break under a tension of...
23. ### Sir Alex's Quote: Football Performance is Low

Hi there, I can remember the quote by sir Alex about football: which is about the performance of a football team. They can be good at one time, but in general they are not good. Their class is low. Can anyone remmember the quote? Thanks
24. ### Happy Birthday, Sir John: Celebrating a Special Day!

Happy birthday sir John
25. ### Sir Isaac Newton Contest: Find the Minimum Length for a Safe Landing

From the Sir Isaac Newton contest: A 1.0*10^3 kg plane is tryin to make a forced landing on the deck of a 2.0*10^3 kg barge at rest on the surface of a clam sea. THe only frictional force to consider is between the plane's wheels and the deck, this braking force is constant and is equal to...
26. ### Sir Isaac Newton Contest

HI! I've looked everywhere for help for this question but i just can't seem to understand it...:frown: The question is below. It is from the SIN contest from 2001, question number 4. I wish they would have the answers posted up on the Waterloo website, but they only have the most recent...
27. ### News Sir Ian Blair's attempt to damage de Menezes name to be investigated

... at long last. http://www.guardian.co.uk/attackonlondon/story/0,16132,1653128,00.html Vaguely promising. Despite de Menezes' parents remaining as vocal as ever on the murder of their son, things have been quiet on this for a while. Blair & co stood by their story until an IPCC report...
28. ### Sir Hermann Bondi (1919 - 2005)

From the Cosmic Variance blog http://physicsweb.org/articles/news/9/9/8/1 http://news.bbc.co.uk/1/hi/england/cambridgeshire/4255806.stm http://en.wikipedia.org/wiki/Hermann_Bondi (I see now that there was a https://www.physicsforums.com/showthread.php?p=748087#post748087 several days ago...
29. ### What's Your First Name?

I have created a thread with the same name as this one, I hope you guys already read it and have a good *feel* toward me... You already know mine so may I ask for your name ? Letting me know your first name doesn't cause any injuries to your typing fingers right ? Lots of people have the same...
30. ### Sir Isaac spoke, and there were light. But why, really?

Some vise guy once stated that "a body in uniform motion stays in uniform motion, if no force is acting on it, a body at rest stays at rest if no force is acting on it." Sure, our universe works this way, I think we all agree on that... but why does it work like this? Does anyone know? As...
31. ### Sir, i get the fllowing reply for my question 'can helium be

sir, i get the fllowing reply for my question 'can helium be changed to hydrogen' '' Helium to Hydrogen requires energy input, for just the same reason that Hydrogen to Helium produces energy. The mass of four protons is greater than the mass of a Helium nucleus (alpha...
32. ### Uncovering the Origins of Spam Names: Sir & Madam Spam

Where do so many spammers get those universally alliterative, metric pseudonyms, i. e., "Gretchen Powers"?
33. ### Sir Thomas More's book Utopia

Sir Thomas More's book Utopia, gives me a account of a society that should be. Simple cotlhes, no money, people share. One thing I despise though is that he uses salves.