saac

Nice write review of  the evscope in this month's issue of BBC Sky at Night magazine.

Jim 

I can see a trend here with what Miguel has experienced.  In my case the power supply was a Maplin unit , but I'm sure these are all cones of each other using same/similar components.  I ended up modding the supply by installing a programmable voltage controller with over-volt protection.  So far all has been good but it definitely looks like these units are prone to failure. 

Jim 

11 hours ago, MarkAR said:

Stunning, lovely surface detail and good proms.

Agreed , beautiful images. Love the black and white one in particular.

Jim 

Good grief it's only just started, garden looking splendid and so peaceful sitting out. Nope I'm not wishing it away so long may it stay - it will be dark for long enough when it comes.  

Jim 

50 minutes ago, Rusted said:

I wrote tartan in my response to Dave and then decided to change it something else.
My having enjoyed only a few, brief years in bonny Scotland, as a bairn and that was in the last century. 
I wonder if Oor Wullie is still alive? His bucket must have <cough> rusted away by now!  👴🏻

He is alive and well still living in Auchenshoogle and kicking about with Fat Boab and Wee Eck  and Soapy Souter   Oh and how could we forget wee jeemy  his mouse. 

Jim 

https://www.sundaypost.com/news/scottish-news/in-full-the-39-oor-wullie-statues-from-dundee-and-tayside-and-what-they-went-for-at-auction/

https://www.bbc.co.uk/news/uk-scotland-tayside-central-49726803

1 hour ago, vlaiv said:

While we are on the subject, can anyone explain this graph:

Yes I can explain it - it's the reason we adopted the SI system

3 hours ago, ollypenrice said:

If the mods will excuse me, flat balls are inherently odd.

I'm an intruding literary type in this conversation so my starting point with your students would be, 'What does bang mean?'  I suspect that after three minutes' discussion the conclusion might be, 'Very little.' Any student arguing that it meant, 'Expansion from a single notional point' would be on a hiding to nothing. At this point 🤣 I'd feel in a strrong position to introduce the idea that 'Bang' was not a bad term to describe an event as yet incomprehensible but, within the limits of our present comprehension, real.

Olly

But Olly can't you hear them refuting the Bang - " but  sir , if nobody was there to hear it, how did it make a sound, what did it bang into, where did it bang" . And where is your Descartes now?  So  down yet another rabbit hole they go with the lesson ticking away.  No Olly , I prefer to kill that misconception before it has a chance to breed for breed it will 😈  A curious thing , from observation in teaching - introduce  a student to something that is false , incorrect , or slightly incomplete and they will remember that with far greater efficiency than any subsequent attempt to correct it !   As we say in Scotland "even the dogs in the street know it "   or  perhaps  N'importe quel quidam le sait..   

Jim 

3 hours ago, goodricke1 said:

And what has a beginning must have an end, right Jim?

Oh I hope it never does; would be sad if we mastered all the secrets of the Universe. What would be left ?  We would have to watch TV   

Jim 

1 hour ago, jindivik said:

 

 

I just like looking through an eyepiece and going *ooooOOooOOooo*

Be careful, that is how science started  

Jim 

1 hour ago, George Jones said:

Any attempt at total understanding of this will necessarily be incomplete. 😉

That's where the fun lies George.  

Jim 

1 hour ago, Tenor Viol said:

If it's any consolation, I'm primarily a 'classical' amateur musician on cello and I also play sax. I've started trying to play electric bass which is utterly alien to me and currently doing my head in! I can read music in all 4 standard clefs, so that's not a problem...

Oddly, if you look at original manuscripts for the renaissance and Jacobean era, authors would put in a preface of their understanding of 'cosmology' trying to link say the theory of music with mathematics, particularly geometry,  and astronomy: the Grand Unified Theory of an earlier era. An example being the English viol player Christopher Simpson's book "The Division Violist" (this is about playing 'divisions', which we would call variations or improvisation). The opening section is all about relating these things together. I have a facsimile edition in my study.       

The  "music of the spheres" ;  like you said maybe an early attempt at a Grand Unified Theory.  I guess it was all part of the "sublime" movement to recognise or reflect the  perfection of nature and to make us part of it.    The linkage between music and mathematics is fascinating. There are lots of YouTube videos which express Pi musically but I've  found this one really satisfying - I find it amazing how the melody he generates with Pi  is pleasing to the ear  - not just random numbers  and notes. 

Re my guitar playing attempts. I was a little concerned that perhaps I'd left it too late in age and that I would just find it too difficult contorting my fingers into unimaginable and unnatural positions   My progress is glacial but I am finding it really enjoyable. I must admit I love just holding musical instruments, but they are more than just pleasing objects - they hold so much potential.  My daughter is my teacher - she is learning the electric guitar too (already plays violin and ukulele  and studies music at school).  To some extent we are learning together but she moves through it way quicker than I do .  I celebrate when I can play a single chord calling her down to listen to my achievement;  she rolls her eyes and says "well done, now what about the other 6  in the opening of Hotel California" ! Praise as only a teenager knows how  

Jim 

1 minute ago, ollypenrice said:

I'm sure it is used by professional cosmologists. It was coined by one, after all, and I've heard several use it.

Olly

It was Olly , but his intentions were less concordant and more deprecating- not all scientist are above such Machiavellian play.  Hoyle as you pointed out earlier being a supporter of the steady state theory was openly hostile to Lemaitre's proposal and ridiculed it at every opportunity.  The recent renaming of Hubble's Law to Lemaitre-Hubble law would no doubt be greeted with similar acerbic commentary from Hoyle. 

Each year I spend as much time correcting the misconceptions of the term "big bang" amongst my students as I do pulling weeds from my garden.  The one useful purpose I will concede to its use is that that it provides the students with an opportunity to arrive at a more secure understanding.  

Jim 

5 minutes ago, andrew s said:

@saac in the Physics Forums link George referenced a book which he recommended.  I would trust his judgement but I have not read it.

Regards Andrew 

Thanks Andrew, could be worth a try to ease lock down confinement. Trying to learn the electric guitar at the moment - every bit as challenging as cosmology and particle physics   

Jim 

38 minutes ago, ollypenrice said:

An interesting link: thanks. However, since it's about flat earth models it doesn't concern itself with spherical ones. The oldest recorded terrestrial globe dates from 150 BC and the oldest surviving one dates from 1492, predating Magellan's first circumnavigation by some thirty years. The replacement of the flat earth model with the spherical one was piecemeal and, indeed, is ongoing since there are plenty of odballs who deny the spherical Earth.

It's an historical curiosity that the term 'Big Bang' was coined by a non-believer, steady state theorist Fred Hoyle and, quite possibly, was coined off the cuff. I think Andrew has pointed us in the direction of understanding why such an unscientific, even facetious, term has taken irrevocable hold. Being the loosest kind of metaphor imaginable it carries no baggage of preconceptions. It is an empty noise, if you like, and so a perfect label for something not conceivable in normal terms. It won't lead you astray because, as a term, it doesn't lead anybody anywhere. I suspect that's why it has stuck.

Olly

And yet it does carry baggage , preconceptions and does lead many astray.  The questions are well known - "what did it explode into ",   "what did it expand into"   "where did it explode".  The term is really only useful as pop art - it has no scientific capital and I would be surprised if it is ever used by professional cosmologists. 

Jim 

23 minutes ago, andrew s said:

At least to me "Primeval Atom" gives the impression that there is an external, extrinsic view. An outside vantage point where you could observe it from and watch it unfold.

Regards Andrew 

 

I know that can be problematic Andrew as it introduces a potential falsehood but I wonder if it is something we can ever truly isolate ourselves from.  Perhaps we, our minds, are that outside vantage point. 

ps - Does not "the big bang" do exactly the same . We ask what it exploded into - there is that extrinsic view again . 

Jim 

1 hour ago, andrew s said:

In mathematics a singularity is in general a point or surface at which a given mathematical object is not defined. 

As that's very abstract so here is a simple example. Consider simple division of real numbers, e.g. 1/n. At the point n = 0 there is a singularity as division by zero is undefined. Informally we say it goes to infinity.

In spacetime, it is similar, again informally, we say the curvature of space time becomes infinite. 

George Jones who posts on SGL said this on Physics Forums.

"I am not sure that there is a completely accepted technical definition.

Roughly, a spacetime is singular if there is a timelike curve having bounded acceleration (i.e, a worldline an observer could follow) that ends after a finite amount of proper time. Singular spacetimes have "edges". How come of it? By the Penrose-Hawking singularity theorems, any "reasonable" classical spacetime must be singular. Very roughly, in any "reasonable" classical spacetime, gravity is so stong that the fabric of spacetime gets ripped, thus creating an "edge"."

Source https://www.physicsforums.com/threads/what-is-singularity.124016/

That is, if you or I approached a spacetime singularity carrying a clock when we got there and the clock would read a normal amount of time i.e. not infinity.

Personally I would say the initial instant t = 0 is singular but I am not an expert.

Regards Andrew
 

Andrew has given us an insightful description here and I'm going to take the time reading through his link to the Physics Forum for further background.  I think with many of these abstract concepts, singularity , infinity  etc ( which are properly rooted in Mathematics) , the difficulty comes in translating these descriptions to what we experience in reality.  In the realm  of Mathematics the presence of infinity generally causes no great concern and there are rules for handling it. However  in physics and the physical world infinity is slightly more problematic  because it is not something we can perceive to be possible. I have read that when Physicists are developing a theory the presence of infinity in the mathematics is usually a sign that something has gone wrong (generally their boundary assumptions ).  For a basic understanding I think it helps if we start with a High School Physics definition  - so for me my understanding of a singularity is " a state (a point )  with no physical dimension  and hence infinity small volume" . To describe that  Mathematically is well outside my understanding so I am left with my basic understanding; I say it quickly and don't dwell too long on it (demons lurk inside)  . As for the conditions at the start of the Universe (the big bang) I think of that singularity (no dimension , infinitely small and infinitely hot )  which then for some reason, not fully understood, went through a period of rapid inflation then expansion.   I don't know how they calculate it but I have read on various text books that the inflation period took the universe from the singularity to something the size of a grapefruit; and we complain of congestion on our roads today !

Jim

9 hours ago, andrew s said:

I don't have any better word that would be memorable and not misleading. Maybe @ollypenrice, @saac or @Macavity has a better term.

Regards Andrew 

For me I think of the singularity coming into existence - it was simply there where before it was not (although before does not necessarily make sense as before did not exist in our traditional understanding). It then expanded almost instantaneously - that for me is the big bang.   No explosions , no bang , but something far more complex and intriguing.  Lemaitre called it the Primeval Atom , not an event but a noun a thing . The media ran with Hoyle's pejorative Big Bang - snappy , catchy eye candy for newspapers, the public, graphic media designers, but less meaningful .  

Jim 

4 minutes ago, ollypenrice said:

Stockhausen's gearchange.

Olly

So he was to blame for Kraftwerk  

Jim

1 minute ago, Macavity said:

Heheh. There is a certain *rhythm* to higher mathematics? I attended a course on Lattice Gauge Theory.
I got LOST in the first five minutes! lol. My thoughts were that I simply didn't have the requisite Maths?
The facility to effortlessly understand "matrix notation" ... A mere "lines-worth" would take me a *day*
to deconstruct?!? There were few Text Books on it then? "Merry banter" aside , Kudos the Theorists! 😸

I guess, like music, it would just flow when you have reached mathematical enlightenment.  My progress through a mathematical  piece was always like playing the gears on an old series 1 Landrover, crunching blindly from one line to the next with long periods of nothing in between.  

Jim

Again we are revisiting 

2 minutes ago, Macavity said:

I may delete the above "personal stuff" rant! But it is a worthy discussion. 😎

I am still something of a devotee of maths (as understood by theorists!).
If someone shows me *credible* maths (even if I cannot understand it)
this has some effect on me... I remember stuff from the film "Hawking":
A (grumpy!) Fred Hoyle vs. (young) Steven Hawking. True or not (my
Sympathy for Fred Hoyle, but I do love the... "I worked it out" bit! lol. 🥳

https://youtu.be/PJsZROmroiY

 

Some people are great musicians , they just intuitively understand it . I think the same of people who have a true understanding on Mathematics - it's in their soul. The best I could ever do was just apply the rules.

Jim 

2 hours ago, goodricke1 said:

 

I don't think anyone is saying science is 'made up' but that it may not be the 'full truth'. It seems every scientific answer, by definition, provokes a further question...

Of course it is not and of course it does. Nobody who's business is science would claim so. The general public on the other hand seem to think they can hold the body science hostage to fortune over that. However, in doing so , they simply confirm their lack of understanding of science.  No Nobel  prize winner wants their discovery to be the final verse of the song; they, like Alexander would weep, for they would have nothing left to conquer . 

Jim 

6 minutes ago, Jimmy Rocket said:

We will just have to have another beer then lol

I was hoping for more than another,  but I will drink to you health even if it is only remotely .   

Jim 

45 minutes ago, Jimmy Rocket said:

Again the termiolgy used is all.... Maybe, could have, might, theory, speculation etc etc.. I am not educated in these things and to be honest some of the wording and descriptions is way above my head but one thing for sure is that the human race is just making up what it thinks happened because that's what we do..... The earth used to be flat and we would fall off the edge into oblivion until someone (MAGELLAN) I think it was proved it to be spherical. 

 

Oh Jimmy Rocket if only we could take this down the pub then what a good night that would be - maybe one day    I'm sorry but if you sincerely believe that we are "making it up" then your understanding of science is not secure.  I can only guess that the-self imposed rigour of science,  the efficacy of its checks and balances and the severity of the burden of confidence that it demands of itself is something that the general public finds difficult to understand.  Now I'm not saying that in an arrogant way, so please forgive me, rather it is  an observation based on similar postings on the subject over numerous threads. Science no more "makes it up"  than a heart surgeon performs a bypass or  Mozart composed the Queen of The Night's aria - they didn't just make it up , they did it with conviction and reason.   Just as  the majority of the human race will never be capable of understanding the profundity of those works , I guess the same holds for the equivalent great works of science - and I include myself amongst them.  I do know however that they are not made up.   I think your opening line is where we can close the gap and agree Jimmy;  terminology is everything here and I accept that to many it may look like science has made it up , all I ask is that you trust me,  it has not.   

Jim 

27 minutes ago, Jimmy Rocket said:

Got to remember that we can only speculate and theorise as what we are trying to fathom is something that we have had no part in, we think we as a human race know what we are talking about but if truth be known we are only guessing. 

SORCE: Stafford2020. 

I don't agree - the very discipline, checks and balances of science lead to a degree of confidence that says we do understand and understand remarkably well.  Read up on the mathematical concept of "sigma confidence level"  and then consider that  sigma level 5 was applied as the bar for discovery of the Higgs boson !  If we could use such confidence levels in any other field of human endeavour then that would be truly remarkable.  In matters of professional  cosmology and particle Physics I think we do have a remarkable understanding of what happened and  the fundamental processes within our universe  - we are finding out more , closer and closer to t = 0.  That we as a species are able to do so is equally if not more so unreasonable. 

Jim 

On 09/06/2020 at 16:52, jetstream said:

I'm not even sure if my question makes sense- this very hot dense state, was it "everywhere"? or was it "in" anything? I remember Alan Guth saying we don't know what banged, where it banged or what it banged in.

You should disregard the term "big bang" completely it is misleading. The term was a pejorative criticism by Fred Hoyle  who disliked Georges Lemaître's  theory (he himself named it the Primeval Atom . It is wholly incorrect and misleading to think in terms of a physical bang - it leads to false assumptions and questions. 

Jim