Recent content by BarbaraDav

(Sorry for my poor English, Please, forgive mistakes, if any.) Dear Friends A system of second order, in normal form, differential equations can be rewritten as a similar first order one, in infinite way (usually that's done introducing simply auxiliaries variables, but it can also be...

I see. Thanks!

(Sorry for my poor English, Please, forgive mistakes, if any.) Dear Friends Thanks for your reply! I agree. May be I am wrong, but Noether's theorem states a sufficient condition for a conservation law to exist, not a necessary one. As an example, as far as I know, the...

(Sorry for my poor English, Please, forgive mistakes, if any.) Dear Friends Not doubts about what is to be meant for "conservative vector field" as far as time independent fields are concerned. But what about non stationary fields? I thought it was a meaningless concept when field is...

Dear Friends Two identical particles are running, in opposite directions, along the x-axis of a reference frame having the origin coinciding with their barycentre; they hits frontally and glue together. Their speeds are ("b" for before collision, "a" for after) : V1b = u V2b = -u Va =...

While having an heavy Google session about the topic we are here talking about, I found (http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.html) what in the following I quote (may be someone is interested ...). Bye. "The clock postulate is not meant to be obvious, and it can't be...

I agree, you got fully the main point. Using a metaphor, you are essentially confirming the clock hypothesis to be a sort of relativistic Euclid's fifth postulate, an assumption no way coming out from the standard hypotheses behind the Lorentz transformations. Do I understand it right ? > an...

Dear Friends Bearing in mind the special relativity definition of "observer" (a system of rods and clock disposed everywhere in the space), what's the operational definition of four velocity (and therefore of four acceleration, four force, etc)? Obviously, no problems in detecting the...

I see. Thanks !

Please, what's "FF frame" ?

Dear Friends A fleet of spaceships is given, each equipped with a differential microwave radiometer, just like COBE was, whose detectors are antipodeanly pointing (this way one should catch blue shifted radiation and the other one red shifted). Could their acquisitions be used to...

Thanks for your reply! In the page you pointed to, I see the equations and the their LaTeX code also, but, as far as I understand, there is no way to have a try there. Anyawy, supposing that standard LaTeX 2.09 "is spoken" in this forum, may be the easiset way is simply copy and paste from...

Dear Sir or Madam I'm a novice here thus I'm probably going to ask a silly question (in a bad English, moreover). Please, can you explain the reason why I can't get the mathematical notation ( \alpha , as an example) displayed clicking on "Preview post" button ? I have been looking...

Thanks for replying: I got it ! Have a great day !

Hi you all. Please forgive my poor English; I will try to put my best foot forward! I'm studying special relativity mostly on Naber's "The geometry of Minkowski spacetime". Just after introducing the concept of Lorentz matrix L (by means of "M" I point its inverse) through the well...