The nature of light
Accelerating charges
Whenever charged particles are accelerated, L I G H T is given off.
Here is the Advanced Photo Source (APS) close to Chicago: A national lab which generates high intensity x-rays (a form of light) for scientific research
A beam of relativistic ($v$ close to $c$) electrons circulates in a storage "ring". It's actually a bunch of straight segments and a few curves...
Bending magnets change the direction of the beam, using the Lorenz Force: $\myv F_L = q\myv v \times \myv B$.
An accelerated electron initially at rest (at left) radiates energy axially away from the acceleration vector (left) if it's given a push.
In the lab reference frame, in which the electron is moving, this energy ends up getting sent 'forward' (tangent to the bend).
This intense burst of x-ray light follows tubes tangent to the bending magnets (or wigglers, another story...) to experimental hutches.
Can you think of a more every-day situation in which charged particle (electrons / protons /...) are accelerating?
What is it about that brick that makes it look as if L I G H T is coming from it? Is the light coming out of the kiln because of a lightbulb?
Thermal motion involves vibrating atoms. Vibration implies acceleration. Acceleration of charged particles implies light.
How does thermal motion change with temperature?
But why can't we see "warm" things...like each other?
Actually, snakes can 'see' warm things with their "pit organs".