geordief

This is the first time I have come across this explanation set out in this way. https://www.forbes.com/sites/startswithabang/2019/12/04/this-is-why-scientists-will-never-exactly-solve-general-relativity/#7b33b37734a8 It was not a surprise to me as the intimations have been there in the background up to now... The gist seems to be that, (so far) one can learn all there is to know about the mathematics of GR but its precise application (even a two body problem) is ,not even tantalizingly completely out of bounds. Does it seem a good article to any one else?

I learned in the last couple of days that Fizeau demonstrated the addition of velocities in 1851 https://en.m.wikipedia.org/wiki/Fizeau_experiment and that it gave a stimulus to Einstein in formulating Special Relativity. Also learned why he called it "Special " (it only applies to uniformly translating frames of reference) Thanks for the book reccomendation Studiot.

Yes it is a bit of a mystery why they do toe the line,but they do. My own view is that they are to some extent representative of the electorate and that reflects very badly on the electorate. Sorry to be so condescending.It does seem obvious ,though.

I meant Trump's supporters.Is that who you understood me to mean? They have to follow their leader and validate his moves apparently.

I don't know why I have that impression, but he seems kind of doddery (like myself) and I find myself willing him to come up with a good answer to the questions. I accept he has great experience and great learning but I am minded of LBJ and his jibe against Gerald Ford not being able to walk and chew gum at the same time. I feel Biden is like that to a lesser degree. He relies on his experience to negotiate new territory but lacks the fast reactions he surely had when younger. I still think that he might match up against Trump as he has a back catalogue of genuineness and likeability that should carry him through. It may be that his greatest enemy is his former self ... He was the person I felt would easily beat Trump but his performances have half reassured me and half worried me. (Thought that talk with Erin Burnet a few nights ago typified that) On balance ,yes I think he is still the best.

They have to focus on him anyway . If Trump brought it up ,not to focus on it suggests he was only using it as a possibly dishonest* tactic. It also has the effect of weakening the father's candidacy (I am not sure how I feel about Joe Biden;he does feel natural,but not so much when it comes to policy where get the impression he is a good learner but lacks insight-maybe a good thing vs Trump ,mind you) * I start from that assumption and give that creep no more benefit of the doubt than absolutely necessary.

In your shoes I might take it in to a professional. Last month I knocked over my tower and the lights went out. I had to wait over the weekend but it just boiled down to resticking some part down again (cost 70 €). Mind you the WiFi is bust since then but I manage without... I hope you get the better of it,though. Computers can suck the life from you

Do you have defrag on Win10? I wonder if that might be of any use if the size of available HD is being misreported.

Tactics are unavoidable (motives are cloudy) but I would argue that for Congress not to have started impeachment proceedings would have been a dereliction of duty. The hope is that the outcome will be favourable but ,if not the forces of anti despotism * will live to fight again whereas ,if the ground was ceded without firing a shot,the next battle would have been on weaker ground. As for the Democrat candidate,they should pick whoever can gather most support in the electorate if they have to stand against Trump. * I hope we can agree that this President is a wannabe despot.

But it still gives problems once it is back in normal mode? Have you tried deleting any very large amounts of file you don't need ?(or saving them temporarily somewhere else) It seems your OS might be misreporting the size of the contents of your HD.....

Thanks.I notice where he says in the preface "Physical objects are not in space but...... spatially extended" Look forward to the delivery of this book next week. Have to laugh though at the idea of "a few happy hours of suggestive thought".. it takes me a good week to read any book at all,let alone this one. edit:it is a 1954 edition

It is this meticulous checking through the logic, here and elsewhere in the paper, that makes Einstein's derivation longer than most modern ones. Naturally he then goes on to prove the compatibility of the two axioms. I have ordered that 1916 Popular Exposition book you recommended in the other recent thread. https://www.scienceforums.net/topic/120443-another-way-of-looking-at-special-relativity/?do=findComment&comment=1122355 Might I expect to find ,in that book the same reasoning(on this particular subject) laid out as in that 1905 paper or might it be "simplified" as the title might lead one to expect?

Well, that Wikipedia page just previously says "The real question here is whether universal lightspeed can be deduced rather than assumed" I have already made enquiries elsewhere as to whether this (well the Universal Speed Limit,which might cover it) might be possible https://www.physicsforums.com/threads/is-the-case-for-a-universal-speed-limit-experimental-or-theoretical.973679/page-2#post-6197363 and came away with the impression that the attempt I was looking at *only seemed to work (if it did) for Galilean Relativity. So would I be right to be sceptical as to the validity of the Single Postulate for now? *https://arxiv.org/pdf/physics/0302045.pdf

"The Lorentz transformations, up to a nonnegative free parameter, can be derived without first postulating the universal lightspeed. " https://en.m.wikipedia.org/wiki/Special_relativity_(alternative_formulations) When I read through this link it is not clear to me how this is shown. Clearly c is the central feature of the Lorentz Transformations ; so is the above quote saying that the invariance of c is not postulated (but that a light speed is) ? If those Lorentz Transformations are derived w/o "first postulating a universal light speed" what does c actually stand for?

@studiot Would you reccommend "Gravitation" by Misner,Thorne et al? I have read it has a good section on vectors/covectors. I will definitely be ordering your last suggestion , E's "Popular Exposition" (embarrassed I haven't had anything like that in the house ever)

When tensors are used is it the case that ,in electromagnetism the calculation is the same whether the FOR is that of the moving charge or the "static" conductor? That is what I seem to take from Markus Hanke's blog https://www.markushanke.net/tensors-for-laypeople/ (about 1/3 of the way down that page) Would seem to be a very interesting property of tensors (don't worry Studiot,I am not banging my head against that brick wall at the moment,although I did try to learn a bit about them some time ago)

Is it quite easy to research this "tensor reformulation of SR" (googling) or might a few pointers be in order?

@studiot is there a particular reason for using +(ict)^2 (or +τ^2 ) than -(ct)^2? It is not just for the sake of "tidiness" ,is it? Do you need all elements of the metric need to be positive for it to be called Euclidean? Does this make the maths easier?

Is this connected to the question of whether the universe is finite or infinite? Ie do the photons meet in a finite universe but not in an infinite one? edit ;seems there is a connection. There is an ongoing discussion over at http://www.sciencechatforum.com/viewtopic.php?f=72&t=35626

I am completely unfamiliar with NLP. I was just trying to respond to Inow's request for some kind of a definition for the OP's "bad boy" If it is a workable definition ,then perhaps it needs exploring. Otherwise what is the point?

Are you?

A bad boy = someone willing and able to ignore conventional behaviour (whilst understanding where the line is drawn)? And do men unconsciously look for women who display the opposite trait?

The "box" in the atom corresponds to the bridge/top fret of the guitar? The discontinuities in QM work against the idea of infinite spatial extent? (that sounds vague;I am fishing ,I suppose)

Well I think it is accepted that the object's field* is infinite in extent. Does that mean we can say the same about the object itself? (or at least stop thinking about the object as able to be described as bounded in any sense at all) Since space can be thought** of as the "mortar" between the "bricks " of objects does the above description of objects require a (struggling for the right word...."complementary"?) similar description of space? Are the "mortar" and the "brick" essentially the same thing? *hope I am right and that all objects have an associated field **this is how I have always thought of it.

Yes, I see that (space seems to be relative in that sense). Is there a sense in which the object and the Space between them are two sides of the same coin? As there is space-time ,can there be "space-object"? (not the same "space") Do objects actually have infinite spatial extent (except when they interact perhaps)?