wave-particle duality and TV reception

On Fri, 12 Dec 2014 17:16:49 +0000 (GMT), Jim Lesurf
wrote:

In article , David Woolley
wrote:
On 12/12/14 13:21, brightside S9 wrote:
For reflections from non smooth surfaces, with roughness much greater
than the wavelength, the reflection is from the whole surface. But it
is not a simple(ish) mathemetical problem to analyse the resultant
reflected waves and build a picture of what gets to the receiver (for
example a viewer of reflections from rippling water). In this example
it is simpler to use the particle theory, and angle of incidence
equals angle of reflection rule.

That only applies when the surface is essentially locally flat at the
wavelength in question and is large in relation to the wavelength.

The idea that

angle of incidence = angle of reflection

is really a part of simple geometric ray theory, not of wave theory. It can
be based on either, given suitable simplifying assumptions.

Wave 'theory' actually comes in various forms which then get used according
to the circumstances. Ditto in fact for ray theories. In general physicists
and engineers dodge having to solve Maxwell's Equations if they can as it
can be a real PITA except in simple situations. So we have a gang of wave
and ray theories to pick from, depending on the case.

I used to point out in tutorials in the past that photons were far smarter
than people. They can 'solve' Maxwell's equations far more quickly when
they have to work out how to deal with hitting a window. :-)

Photons plus window = special purpose analogue computer.

--
Peter Duncanson
(in uk.tech.digital-tv)

On 12/12/2014 22:12, Yellow wrote:

As a girl (now an engineer) who was not allowed to play with her
brother's lego or meccano or train set (he's now a scientist) I found
this all quite interesting.

My sister got a train set a year before I did (on the "old enough to
look after it properly" principle). She played with it a lot - until I
got mine, which suggests that it was one-upmanship rather than interest!

She is not in the least scientific though, and is the type who needs the
instruction book to change the batteries in a torch.

Jim

On 12/12/2014 21:47, Yellow wrote:

In more modern times, from what I have read, girls in all-girls schools
do better in technical subjects than those (the majority) who attend
mixed schools, where the girls tend to shy away from the more
traditionally male subjects.

I went to a co-ed school in the 1960s. On the timetable it said
"Crafts" and the choice was cookery, metalwork, needlework or woodwork
(note in alphabetical order). Anyone could opt for any craft. During
my time at school no boys did needlework, and no girls did woodwork, but
cookery and metalwork attracted both sexes.

Whether similar things happened elsewhere or whether this was a
particularly enlightened school I never found out. The only apparent
segregation was the provision of a Girl Prefects Room and a Boy Prefects
Room, though it was common for some Boy Prefects to join the girls and
vice versa. A new headmaster thought this was entirely wrong and banned
Boy Prefects from going into the Girl Prefects room. So all the Girl
Prefects left their room empty in protest and everybody crammed into the
Boy Prefects room. His new policy was revoked by half-term!

I think the message the school imparted was that if the staff don't
provide any prejudicial guidance, then pupils often don't develop gender
prejudices and are capable of treating each other as a person rather
than a gender. Merely handy in a school, but I found it very useful in
the world of employment.

Jim

"Indy Jess John" wrote in
message ...
On 12/12/2014 22:12, Yellow wrote:

As a girl (now an engineer) who was not allowed to play
with her
brother's lego or meccano or train set (he's now a
scientist) I found
this all quite interesting.

My sister got a train set a year before I did (on the "old
enough to look after it properly" principle). She played
with it a lot - until I got mine, which suggests that it
was one-upmanship rather than interest!

She is not in the least scientific though, and is the type
who needs the instruction book to change the batteries in
a torch.



I hope for your sake and continued living that you sister
does not read this NG!!


--
Woody

harrogate three at ntlworld dot com

On 13/12/2014 16:11, Woody wrote:


I hope for your sake and continued living that you sister
does not read this NG!!


No fear of that. E-mail and Word and Excel is the limit of her computer
skill.

Jim

In article , says...

Yellow wrote:

Just getting the qualifications I needed from an all-girls school in the
70s was a tough job involving my parents visiting the school to sort out
my time table.
So I'm guessing you're a girl then. Welcome to this bastion of male
prejudice. I should introduce myself. I'm the rather dashing, handsome one.

You need to be determined, thick skinned, tolerant to loneliness and
isolation, prepared to put up with discrimination and sexist talk (yes,
even today!)
Why should you care about sexist talk?

Because I am a decent human being and hearing that number of ways the
chaps I work with would like to **** the pretty little thing in the
short skirt who works across the way isn't my idea of fun.

Your mileage may of course vary.


We blokes have to put up with it
all the time, whenever two or more women get together.


Then you will understand exactly what I am talking about.

Good!


Try being the
only bloke in a female environment, like a male nurse or junior school
teacher. The sexist talk is dreadful really, but blokes don't fuss about it.

Where did I state I have ever "made a fuss"? I simply said it is
something you have to put up with which is exactly what you are saying
men do in a similar situation, adding more weight to my first hand
evidence that working in a profession where most are of the opposite
gender is tough.


and able to hold your pee when working on site as they only
Ladies loos will be up in the offices and I am yet to master nipping
round the back and ****ing up against a wall.
If the site lavatories don't have a ladies they are by definition
unisex, so use them!

I can only imagine you have a vision of a single cubicle with a "mens"
label on it rather than a room full of urinals. That is generally what
you find on a shop floor in big old factories.

And despite all my fine engineering skills - I am yet to master the fine
art of the urinal.

But yes, I have used the men's toilets when there are sit downs and
there are no practical alternatives - why would you think I would not
have?


If any blokes complain the management know what
they have to do: provide a ladies'.

What is it you did not understand about my saying there generally being
toilets in the offices, but not on the shop floor?

You know, the bit you snipped?





Bill

PS: I'm a feminist. My wife says so.

Yes, I'm sure you are and I am also sure that you do not find the
thought of a woman engineer any threat to your masculinity, at all. :-)

In article ,
says...

In article , Yellow
wrote:


My boss said he would not consider taking on girl apprentices "as they
need to be able to do the job" and he has passed two comments in my
hearing about a women in her late 20s who works on the shop floor who
shouldn't be carrying heavy items when there is a chap at hand to do it
for her and shouldn't be on her hands and knees doing up huge bolts.

She on the other hand loves her job and is extremely capable, and
wouldn't dream of asking for aid unless she actually needed it.

And when I tell people what I do for a living, you always need to pull
their eye brows back down off their forehead afterwards.

FWIW in my career sic I employed over a dozen postgrads to do research.
Of those, two were women. One was excellent at the work, the other was OK.
i.e. given the small statistical sample, pretty much in line with the men.
And overall similar to the ratio in our undergrad classes.

The excellent one was easily able to get repeat contracts, etc. The work
was very much practical science and engineering as we made things on
contract.

So far as I could tell from my limited experience is / was no real gender
difference in ability.

I agree - it is an individual thing and whether you are male or female
is totally irrelevant when it come to ability.


My impression was simply that long before university
many were losing any interest in science for the kinds 'social'
reasons I mentioned.


Slightly taking a different tact, even the boys seem to be losing
interest. We need more engineers!


I do wonder how much this may vary from country to county, but have no
info
on that.

Jim

On 11/12/2014 05:25, Bill Wright wrote:
The whole science of RF seems to be based on wave theory. Does particle
theory have any place?

Discuss.

This a good starting point.

How to teach quantum physics to your dog.

ISBN 1851687793

If a dog can understand it......................

--
Peter Crosland

Reply address is valid

In article , Yellow
wrote:


Slightly taking a different tact, even the boys seem to be losing
interest. We need more engineers!

Indeed. Alas for a long time now 'injuneering' in the UK has been seen as
having low status and pay, and being 'hard work'. Since the 80s we've been
told we are 'post industrial' and that the income from 'finanance' and
north sea oil are all we need.

Given the shower of chancers and crooks in the city on the one hand and
that oil means engineering anway the mantra always has been fantasy. But
that hasn't stopped goverments and newspapers peddling it.

Instead of producing useful products or building useful infrastructure
we've based our 'economics' on the fantasy that we have increasing 'wealth'
because house and property prices are rising. Invest in housing and get a
return of 10 percent or more. *Try* to invest in engineering or
manufacturing and the finance people will drink your blood. As per the
recent 'Panorama', and countless reports elsewhere on how the city sharks
rip off the rest of us. Couple more reports of how UK banks rip people off
on Radio 4 earlier today (Moneybox IIRC). Yet another of their ways found
to be illegal - well *after* people have been taken by it. And no doubt
we'll end up paying because they are 'too big to fail'. sigh

Thus we now approach a situation where ordinary people find it hard to
afford to live in much of London because "the economy is growing". i.e.
because property prices rise, drawing in finance investors who pay more
expecting the prices to rise further. Drawing overseas investors who outbid
people who simply want somewhere to live or have a factory or office. And
rich people who *can* afford to own property and work/live their want to go
on doing so because quite often "their home makes more money per year for
them than their salary!"

Jim

--
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Indy Jess John wrote:

She is not in the least scientific though, and is the type who needs the
instruction book to change the batteries in a torch.

But you see, often a woman will use the book and succeed when a bloke
will struggle on without it.

Bill