# Heat and space

by Naveen3456
Tags: heat, space
 P: 62 A mass of gas has its molecules moving. (Say in a jar) Another mass of gas has its molecules moving faster. This gas is hotter than the first one. So, heat is motion of molecules. Now, I take this mass of gas into deep space devoid of any gravitation. My questions are, 1. Will this gas cool down. If yes, why? Let me give my detailed insight/conjecture. A body moving in uniform motion does not get affected by the extremely low temperature of deep space and continues its 'motion' unabated. Each molecule is in motion, even if not uniform motion. So, if the gas cools down, why does deep space affect the motion of molecules? 2. Does deep space know the difference between uniform and non-uniform motion?
Mentor
P: 10,809
 Quote by Naveen3456 Another mass of gas has its molecules moving faster. This gas is hotter than the first one.
Not necessarily. If it has a different gas (with lighter particles), the temperature could be equal or lower.

 So, heat is motion of molecules.
Heat is related to the motion of molecules.

 1. Will this gas cool down. If yes, why?

 A body moving in uniform motion does not get affected by the extremely low temperature of deep space and continues its 'motion' unabated.
The uniform motion of a large object as a whole has nothing to do with its temperature.

 So, if the gas cools down, why does deep space affect the motion of molecules?

 2. Does deep space know the difference between uniform and non-uniform motion?
Space does not "know" anything.
P: 62
 Quote by mfb Not necessarily. If it has a different gas (with lighter particles), the temperature could be equal or lower.
Thanks for the insight.

 Quote by mfb Heat is related to the motion of molecules.
Plz explain how is heat 'not' motion of molecules but 'related to' motion of molecules.

 Quote by mfb Does it have contact to the environment? Can it radiate, does it receive radiation?
How to define contact?

The molecules of the gas are colliding with the molecules of the jar. The molecules of gas have forces of attraction and repulsion operating between them. The molecules of the jar are also oscillating and vibrating. In fact molecules of jar are in immediate contact with the space.

Would molecules of jar also slow down?

Would the space that is inside the atoms/nuclei of the jar also cool down and in any way affect the motion of atoms/molecules/nucleons of the jar/gas?

 Quote by mfb The uniform motion of a large object as a whole has nothing to do with its temperature.
When does an object turn large? when we consider 2 atoms/molecules or more than 2?

Suppose the large object enters the area of space having absolute zero temperature. Will its motion still remain unaffected by the temperature around it?

Suppose a single CO2 molecule is moving in deep space away from any soured of gravity or radiation. What would be the scenario? Would the motion of oxygen atoms around the carbon atom slow down?

Can't a single molecule of CO2 be taken as a large object when there is no object nearby with which to compare this CO2 molecule.

 Quote by mfb Space does not "know" anything.
Then how does space/nature see to it that the moment force is removed 'only' uniform motion results without fail.

Do take pains to answer my questions. This is really a laborious job. Thanks in advance.

Mentor
P: 10,809

## Heat and space

 Quote by Naveen3456 Plz explain how is heat 'not' motion of molecules but 'related to' motion of molecules.
An apple is not a tree, but it is related to a tree.

 How to define contact?
Some way to exchange thermal energy.

 The molecules of the gas are colliding with the molecules of the jar. The molecules of gas have forces of attraction and repulsion operating between them. The molecules of the jar are also oscillating and vibrating. In fact molecules of jar are in immediate contact with the space. Would molecules of jar also slow down?
If "gas+jar" cool down, sure.

 Would the space that is inside the atoms/nuclei of the jar also cool down and in any way affect the motion of atoms/molecules/nucleons of the jar/gas?
Empty space does not have a temperature.

 When does an object turn large? when we consider 2 atoms/molecules or more than 2?
When you consider all molecules in an object, independent of the size of the object itself. Apart from that, all objects with ordered motion are "large" in that respect.

 Suppose the large object enters the area of space having absolute zero temperature. Will its motion still remain unaffected by the temperature around it?
Space does not have a temperature. The motion of the particle is always unaffected by empty space.

 Suppose a single CO2 molecule is moving in deep space away from any soured of gravity or radiation. What would be the scenario? Would the motion of oxygen atoms around the carbon atom slow down?
No. Why do you think it could?
Note that a single CO2 molecule does not even have a temperature.

 Space does not "know" anything.
Then how does space/nature see to it that the moment force is removed 'only' uniform motion results without fail.
I don't understand that question.

 Do take pains to answer my questions. This is really a laborious job. Thanks in advance.
I get the impression that you should start with the basics (with a text book, not here), as I guess you have some fundamental misunderstandings, and it is impossible to resolve them if you just keep asking random questions.
P: 62
 Quote by mfb An apple is not a tree, but it is related to a tree. More about heat Some way to exchange thermal energy. If "gas+jar" cool down, sure. Empty space does not have a temperature. When you consider all molecules in an object, independent of the size of the object itself. Apart from that, all objects with ordered motion are "large" in that respect. Space does not have a temperature. The motion of the particle is always unaffected by empty space. No. Why do you think it could? Note that a single CO2 molecule does not even have a temperature. I don't understand that question. I get the impression that you should start with the basics (with a text book, not here), as I guess you have some fundamental misunderstandings, and it is impossible to resolve them if you just keep asking random questions.

But I am afraid to say that you haven't explained anything nor tried to do so.

It seems to me that either you are irritated by such questions or you consider it below your standard to deal in such questions.

BTW, I have studied all these concepts till 12th class from textbooks.

I am under the impression that people on this forum can explain basics more lucidly that a textbook.

Thanks again.
 Admin P: 22,673 There is nothing wrong about mfb answers and I agree with his opinion that you probably have some fundamental misunderstandings about what the heat is. But it is difficult if not impossible to pinpoint where the problem lies just by reading your questions.