On Friday, August 7, 2015 at 10:20:49 PM UTC+1, Dawlish wrote:
On Friday, August 7, 2015 at 9:09:42 PM UTC+1, Alastair wrote:
On Friday, 7 August 2015 21:02:54 UTC+1, Dawlish wrote:
On Friday, August 7, 2015 at 6:08:18 PM UTC+1, JohnD wrote:

It was Dawlish that pointed out the idiocy. Backed by your good self and everyone else who has replied to him, John. I can assure you that Alastair will not forget Dawlish. Sometimes people like this just need to be told, in no uncertain terms, that their ideas are just stupid.

Dawlish,

Answer the four questions.

Cheers, Alastair.

Oh hilarious! I now have 4 questions to answer! Just too funny.

Cold radiation is a figment of your imagination. Get used to it, because it is a fact.

Answer the questions Dawlish, if you can. You demand answers from Lawrence. Here's a taste of your own medicine.

On Friday, August 7, 2015 at 10:19:24 PM UTC+1, Dawlish wrote:

Just answer the questions Dawlish.

On Fri, 7 Aug 2015 13:05:20 -0700 (PDT)
Alastair wrote:

On Friday, 7 August 2015 19:51:32 UTC+1, Graham P Davis wrote:

Oh! So you mean the centrifugal force does exist?


No, it doesn't.
http://scienceworld.wolfram.com/phys...ugalForce.html
https://en.wikipedia.org/wiki/Centrifugal_force
http://www.physicsclassroom.com/clas...rbidden-F-Word

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

Does that mean you agree with me that cold radiation can/does exist?

Of course not. It reminds me of a factitious character from my old home
of Rushden Who was known as Professor Cloddy Darklight who got his name
from inventing dark light. The intention of this invention wasso that
he would be able to plunge a naturally-lit area into darkness. The
professor simply painted a light-bulb black and so, when it was
switched on, the darkness emitted by the bulb, if of high enough
wattage, would overwhelm any other source of light.

In Rushden, when anyone did something silly, they would say they had
done a Cloddy. One that has stuck in my mind was when I was a child
and, one evening, I saw my mother carrying a milk bottle up the stairs.
I asked here what she was doing and she looked at the bottle and said,
Oh, I've done a Cloddy!" She'd gone to the front door with a milk
bottle and hot-water bottle - one of the old stone ones, which I still
have somewhere - and she'd put the hot-water bottle on the doorstep
instead of the milk-bottle.

By the way, I seem to have done a bit of a Cloddy here in misspelling
"fictitious" but after my spell-checker accepted it, I followed up on
it and it seems the wrong word might also be right. OK, I confess
I'd not knowingly heard of "factitious" before.


However, I can't agree with you that the centrifugal force does not
exist :-( As I wrote in my previous post, if there were no
centrifugal force opposing the (centripetal) force of gravity, then
Earth would be pulled straight down towards the Sun. Newton's third
law states that every force has an equal and opposite force. In the
case of the Earth's orbit, the gravitational force is opposed by the
equal and opposite centrifugal force, fictitious or not.

It's not a case of you not agreeing with me, which is not important,
but you're not agreeing with any scientist or even anyone who learned
any science at school. I suggest you read the content in the links I
provided.

The centripetal force, which in the case of the Sun and Earth is their
gravitational attraction, is what keeps the Earth in orbit around the
Sun. If the centripetal force were really equally balanced by this
fictitious centrifugal force the Earth would fly off at a tangent as
there'd be no force to keep it moving in a circle.


But, let's not fall out about it :-)


Indeed not.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

On 06/08/2015 15:52, Alastair wrote:
Dawlish,

On Page 576 of University Physics with Modern Physics, Technology Update, Thirteenth Edition (2010), which continues
to set the benchmark for clarity and rigor combined with effective
teaching and research-based innovation, they write:

"Radiation. Heat transfer by radiation is important in some surprising places.
A premature baby in an incubator can be cooled dangerously by
radiation if the walls
of the incubator happened to be cold, even when the air in the
incubator is warm.
Some incubators regulate the temperature measuring the baby's skin ..."

This doesn't sound at all right.

Convection dominates radiation transfer at temperatures below about 53C
under NTP ambient laboratory conditions - the baby is cooled by a pool
of cold air due to a cold draft coming off the cool glass walls.

Hot objects radiate heat which warms adjacent objects. Cold objects radiate cold which cools adjects objects.

This is complete and utter clueless dross. I hope that it is you who
have misunderstood what the textbook actually says, but I have a bad
feeling this may well indicate the dumbing down of the hard sciences.

*Everything* radiates thermal energy according to Plank's law usually
approximating a black body according to its temperature.

https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Stefan...3Boltzmann_law

Energy *transfer* between bodies varies according to the difference
between the fourth power of their absolute temperatures. Net energy flow
always being from the hotter to the cooler body.

The Earth's temperature ~290K is determined by being in thermal
equilibrium with one sun at 5500K subtending an angle of 0.01 radians
and ~4pi of empty space radiating at 4K (the microwave background).

Earth gains energy from the sun and thermalises it and loses energy to
the sky but nowhere is there any "cold radiation" it is an idiotic
phrase worthy only of charlatans and fools.

Everything radiates thermal radiation to everything else in an amount
determined by its absolute temperature and surface emissivity.

The latter is difficult to demonstrate because it is more difficult to maintain a constant cold temperature than a high temperture.
The latter is easy using electrical heating. However, holding a
thermnometer over an object taken from a freezer will cause the
temperature shown to drop.

Yes. Because the cold object below the thermometer is no longer
radiating at the same temperature as the rest of the surroundings. It is
the thermometer that is on average donating heat radiation to the cold
block which is not being returned any more in sufficient amount to
maintain its temperature. It is not evidence of "cold radiation" the
term is a complete misnomer and dangerously misleading.

I hope you will now realise that you are wrong, will apologise and admit your mistake. Cold radiation does exist.

Cheers, Alastair.

Sorry no it doesn't. If that "physics" book really does say what you
claim then it has no right to be sold as a university textbook!

I don't often defend Dawlish but on this point he is absolutely correct.

--
Regards,
Martin Brown

On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.
During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.
In science it is important to understand the energy balance at the surface in question.

I hope this helps.

Len
Wembury

---------------------------------------------------------------------------

On Saturday, August 8, 2015 at 10:14:21 AM UTC+1, Len Wood wrote:
On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.
During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.
In science it is important to understand the energy balance at the surface in question.

I hope this helps.

Len
Wembury

---------------------------------------------------------------------------

Alastair will not be persuaded, even if every single physicist on the planet queues up to tell him, as Martin says, that what he is talking about is 'complete and utter clueless dross'.

Not a single other person in this newsgroup, who has a hint of a brain, supports this utterly ridiculous concept of 'cold radiation'. I really do mean; not **one**

Warmer objects are not cooled by cold radiation from cooler ones. No ifs, or buts, it **cannot** happen with current knowledge of physics.

On Saturday, August 8, 2015 at 12:17:14 AM UTC+1, Alastair wrote:
On Friday, August 7, 2015 at 10:20:49 PM UTC+1, Dawlish wrote:
On Friday, August 7, 2015 at 9:09:42 PM UTC+1, Alastair wrote:
On Friday, 7 August 2015 21:02:54 UTC+1, Dawlish wrote:
On Friday, August 7, 2015 at 6:08:18 PM UTC+1, JohnD wrote:

It was Dawlish that pointed out the idiocy. Backed by your good self and everyone else who has replied to him, John. I can assure you that Alastair will not forget Dawlish. Sometimes people like this just need to be told, in no uncertain terms, that their ideas are just stupid.

Dawlish,

Answer the four questions.

Cheers, Alastair.

Oh hilarious! I now have 4 questions to answer! Just too funny.

Cold radiation is a figment of your imagination. Get used to it, because it is a fact.

Answer the questions Dawlish, if you can. You demand answers from Lawrence. Here's a taste of your own medicine.

Exactly what questions have you asked?

I learnt my Kinematics at University while studying for an engineering degree, not from some smart alec teacher. Yours wasn't Dawlish by an chance? OK the centrifugal force is not a force field like gravity, magnetism, etc., but the centrifugal force can be calculated, see your link which describe it http://scienceworld.wolfram.com/phys...ugalForce.html . That link is proof enough for me. Strange that one can get so many hits for centrifugal force if it does not exist.

By the way, if you do release the centripetal force, e.g. a hammer at the Olympics games, then it will fly off, just as you predict if the centrifugal force did exist.

As far as your fictitious Professor Darklight is concerned I am quite willing to disbelieve in his existence, or that his dark lights would have worked. However, if he had replaced the bulbs in the lamp posts with his bulbs, then the street would have been darker, just as if you shine cold radiation on an object it becomes colder.

Professor Darklight never carried out his experiment but Professor Pictet did. And he got the results I have described.

On Saturday, August 8, 2015 at 10:14:21 AM UTC+1, Len Wood wrote:
On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

No, in that case, I am calling the absorbed radiation cold radiation. The net radiation is the emitted less the absorbed. Hence the object will cool.

On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.

It cools because the absorbed radiation is colder than that which it is emitting.

During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

A better name for solar radiation would be hot radiation rather than warm. If you call it warm then I should call my cold radiation cool.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.

Agreed, but if you call the radiation emitted by cold bodies cold radiation then it makes sense to say that it will cool a warmer body which absorbs it.

On Saturday, August 8, 2015 at 12:26:34 PM UTC+1, Alastair wrote:
I learnt my Kinematics at University while studying for an engineering degree,

There, apparently, you learned this:

'if you shine cold radiation on an object it becomes colder'.

I'm sure it wasn't your teachers, it would have been you simply not understanding basic thermodynamics.

Just hilarious to watch you here, Alastair. It really is bsolutely hilarious.