Question: Why does everything seem to be wrapped in aluminium foil?

Andrew Thomas answered on 28 Jun 2012:

Hi gmorris. The experiments we do at synchrotrons (where the photos on my profile are taken) are done in ultra-high vacuum. The pressure inside the chamber is 1 x 10^-10 millibar or 0.0000000000001 times atmospheric pressure (one million millionth of atmospheric pressure – even lower than in space). To do this we have extremely powerful pumps which will get down to low pressures. The problem is that gas molecules stick to the walls of our chambers and are constantly coming off and limiting the vacuum at room temperature so we heat the whole chamber to around 140-160°C for 24 hours. This makes the gas come off the wall.

The foil serves two purposes – firstly it helps spread the heat more evenly and secondly our chambers are made of steel and have thick glass windows. Since steel cools faster than glass, when we turn the heat off the glass might crack so we use foil to help cool the windows at the same rate as the steel.