[hamdani yusuf (OP)]

We Cannot Feel Temperature

In this installment of "Thermal Shorts", I explain why metal feels colder than wood, even though they are at the same temperature.

Content:
0:00 Intro - We cannot feel temperature
1:00 The Mechanics behind Heat Conduction
2:43 The Description of Heat Conduction
5:05 The Ice Cube Experiment

[Bored chemist]

Where did you make that statement?

Do you think that the zero point vibration of a lattice has friction?

[Bored chemist]

We Cannot Feel Temperature

In this installment of "Thermal Shorts", I explain why metal feels colder than wood, even though they are at the same temperature.

Content:
0:00 Intro - We cannot feel temperature
1:00 The Mechanics behind Heat Conduction
2:43 The Description of Heat Conduction
5:05 The Ice Cube Experiment

This issue is interesting physiology; it is not physics.

[hamdani yusuf (OP)]

Where did you make that statement?

Do you think that the zero point vibration of a lattice has friction?

https://en.wikipedia.org/wiki/Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.[2][3] Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of the processes involved is called tribology, and has a history of more than 2000 years.[4]

https://en.wikipedia.org/wiki/Friction#Internal_friction
Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.

Plastic deformation in solids is an irreversible change in the internal molecular structure of an object. This change may be due to either (or both) an applied force or a change in temperature. The change of an object's shape is called strain. The force causing it is called stress.

https://en.wikipedia.org/wiki/Friction#Radiation_friction
As a consequence of light pressure, Einstein[73] in 1909 predicted the existence of "radiation friction" which would oppose the movement of matter. He wrote, "radiation will exert pressure on both sides of the plate. The forces of pressure exerted on the two sides are equal if the plate is at rest. However, if it is in motion, more radiation will be reflected on the surface that is ahead during the motion (front surface) than on the back surface. The backward-acting force of pressure exerted on the front surface is thus larger than the force of pressure acting on the back. Hence, as the resultant of the two forces, there remains a force that counteracts the motion of the plate and that increases with the velocity of the plate. We will call this resultant 'radiation friction' in brief."

Considering the types of friction above, I think the answer is yes.

This resistive force by Lenz' law below also acts like friction.

A magnet is dropped down a conducting copper pipe and feels a resistive force.  The falling magnet induces a current in the copper pipe and, by Lenz's Law, the current creates a magnetic field that opposes the changing field of the falling magnet.  Thus, the magnet is "repelled" and falls more slowly.

[alancalverd]

This issue is interesting physiology; it is not physics.

Beg to differ slightly on this quite complex issue.

We sense temperature differences quite well, with sensitivity 0.5K or less, either between hands (the most frequently used sensor) or between body and ambient, but sensation depends on the rate of heat transfer as well as its direction. Whilst cold metal may give a stronger immediate touch sensation than cold wood, the same is also true of hot metal and hot wood.

If the sample is small and thermally isolated, both metal and wood will equilibrate to your skin temperature  and the sensation will disappear, but if they are large and maintained at constant temperature, the thermal gradient across your skin will depend on the conductivity of the material. The epidermis is effectively dead, and the active sensors are in the dermis, so if the object's conductivity is low the sensor will gradually return towards body temperature as the blood flow tries to regulate and nullify the sensation (which is why we have the sensors in the first place)  but if the object conductivity is high you won't be able to compensate for the heat loss. 

In summary: yes, we do sense temperature, but even before we get to  neurophysiology, the physics is  more complicated and dynamic than an ideal thermometer.

[Bored chemist]

Considering the types of friction above, I think the answer is yes.

Then you are wrong.
The ZPE can't be lost to anything (including any sort of friction) because that would mean that the molecules stopped vibrating and that would violate uncertainty.

[hamdani yusuf (OP)]

Considering the types of friction above, I think the answer is yes.

Then you are wrong.
The ZPE can't be lost to anything (including any sort of friction) because that would mean that the molecules stopped vibrating and that would violate uncertainty.

How do you completely block radiation from the environment?

[hamdani yusuf (OP)]

In summary: yes, we do sense temperature, but even before we get to  neurophysiology, the physics is  more complicated and dynamic than an ideal thermometer.

The invention of temperature as a concept was a necessity since it's essential to our survival. Earliest objective measurement of temperature was conveniently done by using conduction as heat transfer method, which requires mechanical contact between the measured object and the measuring device.
Non-contact temperature measurement using radiation was invented much later.

[Bored chemist]

How do you completely block radiation from the environment?

Why did you think that question was relevant?

[hamdani yusuf (OP)]

How do you completely block radiation from the environment?

Why did you think that question was relevant?

Because you expect that friction would cause molecules to stop vibrating while ignoring the fact that they are continuously perturbed by various radiations from the environment.

[Bored chemist]

Because you expect that friction would cause molecules to stop vibrating

That's the exact opposite of what I said.

[hamdani yusuf (OP)]

Because you expect that friction would cause molecules to stop vibrating

That's the exact opposite of what I said.

What do you mean in this post?

Considering the types of friction above, I think the answer is yes.

Then you are wrong.
The ZPE can't be lost to anything (including any sort of friction) because that would mean that the molecules stopped vibrating and that would violate uncertainty.

My interpretation was you think that friction, if it exists in molecular level would stop vibration. It makes you concluded that friction doesn't exist in molecular level.

[Bored chemist]

Re "What do you mean in this post?"
I meant "The ZPE can't be lost to anything (including any sort of friction) because that would mean that the molecules stopped vibrating and that would violate uncertainty.".

My conclusion is that the motion associated with the  zpe is frictionless (strictly, lossless).

[hamdani yusuf (OP)]

My conclusion is that the motion associated with the  zpe is frictionless (strictly, lossless).

It seems like our disagreement stems on what counts as friction.
Here's what Chatgpt says.

At the molecular level, motion isn?t exactly "frictionless," but it operates differently than friction at the macroscopic level.

In a traditional sense, friction arises from physical interactions and resistance between surfaces. On a molecular scale, however, molecules experience interactions like collisions, van der Waals forces, and electrostatic attractions, which affect their movement. While these interactions cause energy dissipation and slow down molecules, it?s different from what we typically consider friction.

In a vacuum at extremely low temperatures, where molecules have minimal energy, they might appear to move "freely" in the sense that they aren?t slowed down by other particles. However, at typical conditions, molecules still experience resistance due to their interactions with other molecules, leading to effects like viscosity in fluids or drag in gases. This is why we can see molecular motion as being "resisted," but calling it friction doesn?t fully capture the behavior at such a small scale.

[Bored chemist]

Here's what Chatgpt says.

Can you get it into your head that ChatGPT is monumentally stupid?

https://community.openai.com/t/incorrect-count-of-r-characters-in-the-word-strawberry/829618


Your post is like saying "I asked a five-year-old and they said..."

Stop using it.

[alancalverd]

 

ChatGPT is monumentally stupid

Hardly surprising. In science there is usually one correct answer and an infinity of wrong ones. If you have a bot that scans the internet to form a consensus, it will at best give you a fuzzy answer, hedged about with "maybes", and at worst settle on popular nonsense rather than a little-known or counterintuitive truth.     

Fact is that friction is a combination of geometry and chemistry, which is why we like to make bearings with dissimilar metals: highly polished clean surfaces of the same metal tend to stick together, which is quite a problem in high-vacuum systems.   

[hamdani yusuf (OP)]

Here's what Chatgpt says.

Can you get it into your head that ChatGPT is monumentally stupid?

https://community.openai.com/t/incorrect-count-of-r-characters-in-the-word-strawberry/829618


Your post is like saying "I asked a five-year-old and they said..."

Stop using it.

Last time I checked it gave the correct answer. Fierce competition forces AI developers to continuously improve their models. The rate of improvement is exponential.
That aside, can you point out which part of its answer is false?

[hamdani yusuf (OP)]

Hardly surprising. In science there is usually one correct answer and an infinity of wrong ones. If you have a bot that scans the internet to form a consensus, it will at best give you a fuzzy answer, hedged about with "maybes", and at worst settle on popular nonsense rather than a little-known or counterintuitive truth.

Some AI models are strictly trained using articles in encyclopedia and peer reviewed papers in reputable science journals.

[alancalverd]

And the result is still crap. See above.

[Bored chemist]

That aside, can you point out which part of its answer is false?

None of it is relevant.
GIGO

I said "The ZPE can't be lost to anything (including any sort of friction) because that would mean that the molecules stopped vibrating and that would violate uncertainty.".
And that's still true.
The GPT poetry doesn't even refer to ZPE, but that may not be its fault.

What question did you ask it?