Why is 100% efficient thermal insulator impossible?

[linux kid]

Somebody told me this and I have yet to figure out even if the statement is true or not.

 

[DaveC426913]

Because if it could be done, you could stop entropy. Which you can't.

Even if you could stop conduction of heat, how would you stop a body from radiating heat?

 

[anantchowdhary]

If u can stop entropy its lik saying u cud stop time.SO i guess its not possible

 

[DaveC426913]

If u can stop entropy its lik saying u cud stop time.SO i guess its not possible

Translation: If you can stop entropy it's like saying you could stop time, so I guess it's not possible.

 

[Gokul43201]

Stop entropy? What does that mean?

Why is 100% efficient thermal insulator impossible?

Somebody told me this and I have yet to figure out even if the statement is true or not.

If the question was, is there such a thing as a perfect insulator (i.e., has zero thermal conductivity), then the answer is "yes, a vacuum". Of course, you can't make a true vacuum, nor does a vacuum prevent radiation.

 

[russ_watters]

I like to look at such questions backwards: how could you make a perfect insulator? There are 3 types of heat transfer: conduction, convection, and radiation...

As Gokul said, a vacuum will stop conduction and convection completely, but we can't make a perfect vacuum and even if you could, you'd have to support the structure with something. So you can't completely eliminate either conduction or convection in a device (though you can eliminate conduction between objects that aren't touching. But you can get either well above 99%.

Stopping radiation is much more difficult than stopping either conduction or convection because it requires a perfect mirror that is perfect at all frequencies of radiation. And though you can get mirrors at in exess of 99% reflectance, the frequency range is limited.

 

[DaveC426913]

then the answer is "yes, a vacuum". Of course, you can't make a true vacuum, nor does a vacuum prevent radiation.

Since a vacuum doesn't prevent radiation, how does that make it a perfect insulator?

 

[disregardthat]

It doesn't because it does not prevent readiation as gokul said.

But this perfect vacuum must exist a place farther away than light has reached since bing bang? Because if no radiation or mass have reached the point, nothing can be there.