Can you really block thermal imaging with glass or aluminum foil? If not, what can?
Well, silly! That keeps the space aliens from getting to them! Their brain sucking devices can't penetrate aluminum foil. Seriously, though, it's a redneck attempt to block the direct sun and keep the room from heating up.
Yes you can better with aluminum foil and somewhat little with glass. Thermal imaging takes a heat image based on an object radiating out more heat than it's background. The heat is all in the infrared so does not depend on visible light Aluminum foil is very effective in radiating back infrared waves, and very little infrared will pass thru the foil. Glass will let about 90 percent come thru, but it depends on the angle of incidence, with higher angles reflecting more infra red. But Stand in front of a window with the sun shining in, and you see how much infrared from the sun you can feel on your skin . Foil is probably about 95 % effective in reflecting infrared, depending on how shiny it is. In real life situations that is why the inside of thermos bottles are shiny aluminum (or silver) to reflect infrared heat, and fireman wear aluminum suits into fires to protect from the radiant heat ,which is the infrared. So if you wore an aluminized or silverized suit , a thermal imaging device would have a hard time seeing you from the background radiation given off by other objects. You have to give off more radiant heat than surrounding objects to be noticed by a thermal camera
