This glorious spread of food at TEDxSydney was crowdsourced from local growers. Photo: courtesy of TEDxSydney

Catering a TEDx event can be — how do you say it? – costly. So we think it’s so cool that the organizers of TEDxSydney decided to crowdsource the food for the 2,200 people attending the event in May. All the food in the amazing spread above comes from community gardens and from plants grown in the backyards, windowsills and balconies of both attendees and generous urban farmers throughout New South Wales. This incredible crowdsourcing was organized by Sydney’s Grow it Local. More than 250 local growers donated food in the end.

These are the lengths people go to for TEDx events, dozens of which are held around the world every week. From those events, the TEDx team chooses four favorite talks each week, highlighting just a few of the enlightening speakers from the community and its diverse constellation of ideas. Below, listen to this week’s talks — on topics ranging from public policy to the future of humanity.

Make public policy more fun: Vass Bednar at TEDxToronto
Is public policy just for policymakers? Absolutely not, says Vass Bednar. In this impassioned talk at TEDxToronto, she explains how to put the public back into public policy, by taking a cue from hacker culture and allowing governmental systems to be open source — with apps, games, and lots of sharing. (Filmed at TEDxToronto)

How does the War on Terror end?: Chris Fuller at TEDxSWPS
What’s driving the global War on Terror? It’s not necessarily what you think, says historian Chris Fuller. At TEDxSWPS, he explains how the effects of economic forces along with climate change — rising temperatures, arid farmland, flash floods — are driving citizens in North Africa to join militant groups like Al Qaeda for solutions — and makes a call for Western nations to change their approach to combatting terrorism. (Filmed at TEDxSWPS)

The multiplicity of truth: Julian Baggini at TEDxKingsCollegeLondon
There is no one lens that can bring the truth about reality into focus. Instead, Julian Baggini suggests in this talk from TEDxKingsCollegeLondon, the truth is “nothing more than a totality of different points of view.” The trick, he suggests, to finding truths about the world or ourselves is finding the right lenses for the right occasions and knowing which ones bring the truth into focus and which ones distort reality.(Filmed at TEDxKingsCollegeLondon)

Today, and the future of humanity: Nick Bostrom at TEDxOxford
Our ways of life are at risk. From rising sea levels to nuclear threats, humanity could easily end. How often do we consider the full breadth of these risks when we make decisions; big or small, political or personal? At TEDxOxford, Nick Bostrom describes the exponentially spiraling effect that seemingly trivial actions today could have on the distant future and argues that we need to be more mindful of our decisions. (Filmed at TEDxOxford)

Below, some highlights from the TEDx blog this week:

• 5 TEDx Talks to make learning a language easy
• A look at the Map Your Memories project, from a TEDxWilliamsburg speaker
• 5 talks in Russian: TEDx’s first Russian playlist