Re: simple but deep!
- From: "Jim Hill" <outcrops@xxxxxxxxxxxxx>
- Date: Wed, 31 Aug 2005 23:47:28 +0100
"adn" <signus.x1@xxxxxxxxx> wrote in message
news:1125521425.114062.180170@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> [Jasen Betts]:
>> a quantum of electromagnetic energy.
> [adn]:
> What do u mean by saying a" quantum" of electromagnetic energy?
[Jim H]:
Electromagnetic energy (radio waves; light; x-rays; etc) is radiated in
little "packets" called "photons".
These photons leave a light source (e.g. a torch bulb) a bit like bullets
leaving a machine gun.
The gun can shoot any whole number of bullets.
Likewise, the light source only radiates whole numbers of photons.
One photon is the smallest amount of light that the source can radiate.
This smallest amount that sometimes called the "quantum".
> [adn]:
> How do u get this quantum?
[Jim H]:
They were initially identified as a result of experimental evidence.
Subsequent mathematical analysis of the experimental data has given an
elaborate theory
(sometimes called "quantum mechanics") to account for certain random aspects
of their behaviour.
> [adn]:
> u know that photons & electromagnetic waves are both real things (I
> guess!)
[Jim H]:
Photons and e.m. waves are not necessarily "real" in a concrete sense.
They are related "theories" each backed up by mathematical systems intended
to predict,
and/or explain the behaviour of light and similar forms of energy.
[Jim H]:
The numbers which appear on a bank statement may represent "real" money
(e.g. coins) that you actually put into, or took out from it.
However, your bank charges are not physically taken out of a "real" pile of
your money.
They do not represent actual physical movement of cash in the same "real"
sense of "movement"
when deposits and withdrawals are made in person.
> [adn]:
> and if photon is a way for transmitting energy (or as u said
> "an energy's way of traveling") then what is an electromagnetic wave?
[Jim H]:
Photons and e.m. waves are not alternative ways of transmitting the energy,
they are alternative theoretical methods of accounting for particular types
of behaviour.
The behaviour is something governed by the natural laws of the universe,
and we are stuck with those laws whether we like it or not.
> [adn]:
> Of course it is another way for this goal. So I want to know whether
> there is any relationship between these two ways (or better say these
> two characteristics) & we can convert them to each other.
[Jim H]:
There are relationships between them, but probably not in the not in the
sense that you mean.
If you toss a coin 1000 times we are confident that there will be "near to"
500 heads, and 500 tails.
This is because the probability of getting a "head" is equal to the
probability of getting a "tail".
Sadly a knowledge of this gives us absolutely no clue whatsoever what the
result of a single toss will be,
nor does any sequence of recorded results help us to predict any future
sequences.
[Jim H]:
Similarly, a knowledge of the large scale behaviour of e.m. radiation using
the wave theory
(e.g. to predict the variation of voltage within the aerial of a radio
receiver)
gives us no help in deducing the random behaviour of the individual photons.
--
Regards - Jim
> THX
> --adn
>
.
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