figureLighting up Lingshed monastery, high up in the Himalayan mountains. [Paula Bronstein/IEEE Smart Village Project]

“The International Day of Light is a gift from a political body—UNESCO—to us. How we use it is up to us.”
—John Dudley

Q. The International Year of Light, in 2015, was a very successful event. What made you want to extend that into an annual day of light?

I was really pleased to see how much collaboration there was between different sectors of the optics community during 2015; it had an enormous constructive benefit for everyone. And we all thought it was nice to consider a mechanism for at least once a year to try to continue that multipartner collaboration.

Also, during the International Year of Light and even before, it was apparent that many organizations had thought of an international day of light, but not in a coordinated way. It was clear that the community wanted a permanent legacy of the Year of Light, and a UNESCO representative pointed out that an international day existed as a mechanism for such a legacy—if we wanted to do the extra work to put that on the political agenda.

Q. Speaking of extra work, it seems that organizing an “international day” would have a different set of challenges from an “international year.”

The main challenge is the obvious one: It comes around every year. The number of hours that have to be invested is fewer compared to a year-long celebration, but the structure that supports the work has to be one that can be sustained over a multiyear period.

A key goal of the International Day of Light is to improve public understanding of how light and light-based technologies touch our daily lives and are central to global future development. Trying to get the public interested in science on a particular day rather than over the course of a year is a more complicated and difficult thing to do, I think. But we wanted to continue the gains that were made during 2015 in an annual event.

Q. In addition to the day’s focus on the science of light, there’s a cultural dimension as well.

Yes. UNESCO focuses on education, science and culture. We know about education and we know about science—this is our business as usual. What the International Year of Light really highlighted for me was the fact that we’ve been missing for many years an opportunity to talk about the broader cultural impact of light in society.

We are often a little reluctant to enter into conversations about the social impact of the technologies we invent. But, in fact, we should be having these conversations. And we now have an opportunity one day a year to hold events on broader topics related to our discipline if we wish.

The International Day of Light is a gift from a political body—UNESCO—to us. How we use it is up to us. Some partners will choose to always focus on technology and science. Others may decide, well, this year, we’ll focus on art history and how optics links with understanding artworks; and next year we’ll get the local town hall involved and have some discussions about social-media usage, screens at night time and the effect on sleep. We must provide context for an event like this; it can’t be organized in a vacuum.

Q. Let’s talk a bit about this year. What are a few of the planned events that, to you, exemplify the diverse ways that people are marking this day?

It’s hard to narrow it down to just a few! In my home country of New Zealand, though, they’re organizing an event in which university staff are going into a local science museum—dressed in costume as historical scientists—and holding a one-day event with children. Bringing this historical dimension to outreach is something I’ve never seen before.

In India, there’s an event at one of the highest plateaus in the world. They’re working with an NGO that has lit up a village and a monastery there with solar lights, and they want to do astrophotography at the lit-up monastery at night.

There’s another event in Yap, Micronesia, where a Hawaiian-based nonprofit is opening what they call a sustainable eye surgery—the first eye care clinic on this Micronesian island. We never had any penetration in Micronesia during the Year of Light, but this nonprofit seems to be an ideal vehicle to go there.

Q. Do you have any thoughts on ways to keep this fresh each year?

That’s something we’ve thought a lot of—should we focus on a particular theme every year, or encourage people to build events on any theme. I think the solution we’ve found for future years is to focus one or two international flagship events on particular topics that have been decided by UNESCO and the steering committee to be of interest. But apart from these high-profile, big congresses, the activities around the world we will just let bubble up spontaneously. You want to have the possibility for anyone, anywhere to do an event that’s in any way related to light. 

OSA is a founding member of the steering committee of the International Day of Light. To learn more about IDL 2018, please visit