Portals are not Aperture Science's only remarkable scientific accomplishment. Among their other inventions is the Light Bridge, that provides a stable and seemingly immaterial surface that people can stand on. The bridge can also be turned on or off instantly.
How does it work and is it really made of light?
It certainly emits light but it most definitely isn't made of it. For light to be able to withstand the weight of a person would require an amount of energy that would have to be directed upwards and that would be sufficient to fry them instantly.
There is little information available on Light Bridges but similar technology has been mastered by others. One declaration we were able to get from an Aperture representative is the following:
"If you rub your cheek on it, it feels just like being outside, with the sun shining on your face. It will also set your hair on fire, so don't actually do it."
This is because the bridge seems to be a stationary wave of photinos, the supersymmetric partners of photons. Around the surface of the bridge, there is an evanescent wave that is characteristic of a phenomenon of total reflection.
The tricky part is that what is being totally reflected on the surface is the quantum wave function of all fermions above the bridge. In other words, the force exerted by the bridge on what stands on it is purely quantum mechanical in nature, similar to what keeps electrons in separate atomic orbitals or to what keeps a neutron star from collapsing further. It could even be seen as a sort of reverse-quantum-tunneling effect, where objects cannot possibly move any farther. An anti-portal of sorts.
Now light can still pass through because it's made of bosons, of course, which explains the translucency. The blue color is due to the disintegration of some of the photinos that form the bridge.
There is a cylindrical version of the light bridge that is used as a tractor beam and that is obtained by not making the photino wave exactly stationary.
That is it for today. I'll take questions now.