Joule Effect and Matter in Space
Name: Paillusson F.
Is there any matter in space?
This is my question because there is cold or hot in space and Joule effect
is not possible without matter, nevertheless my physics teacher told me
the sound cannot travel through the space because there is no matter
there. So I am lost.
(I am sorry if you cannot understand my phrases because I do not speak
English very well.)
Kinetic energy can be transferred between objects without ever having them
come into contact! Recall the three classic mechanism of heat transfer:
conduction, convection, and radiation (http://www.lanly.com/heating.htm).
Heat from the sun, for instance, is transferred to us not by direct
encounter, but by electromagnetic radiation emitted by the sun and absorbed
by the earth (and us).
So, an object in space (a rock, piece of dust, dilute gas) can be hot or
cold. It can become hot by absorbing radiation, and it can become cooler by
emitting radiation. You are correct, a vacuum itself cannot be hot or cold
- only an object inside it.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012