BBC Inside Science

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Tom Whipple travels 100m below Switzerland to the tunnels of CERN's Large Hadron Collider (LHC) where the beams have been powered down to begin the High-Luminosity LHC upgrade. Paulo Fessia, deputy head of the upgrade project, shows us what they're doing and why.

In one of the cavernous halls on the site, Antti Onnela explains what the machinery is used for when it's not smashing particles together; understanding the formation of clouds. With Eva Sommer, Run Coordinator of the project, we learn how clouds are born from aerosol particles in a specialised chamber and how this informs climate models.

We also learn about what many hope is the next phase of European particle physics, the future circular collider (FCC). The FCC is due to be 3.4 times larger than the LHC and cost around £14 billion. Guy Wilkinson tells us why he believes the cost is justified.

And what will they do with all the substrate that is cleared for the new tunnels? Tom visits plant scientist Christiana Staudinger at the OpenSkyLab project in the fields above CERN's tunnels where they are making soil in hopes of replenishing the world's dwindling sources.

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