20 May Programme

UNESCO Headquarters, Paris ⋅ 20th May 2025

20 May 2025 will be the 150th anniversary of the signing of the Metre Convention and therefore a special World Metrology Day. It will be marked by an event held to celebrate the achievements of 150 years of the BIPM.

Speakers’ contributions will span all the way from the history of the BIPM as one of the oldest international organizations of the world to the current challenges in metrology. They will focus on the scientific achievements of 150 years of metrology and the unique international scientific collaboration under the Metre Convention.

09:30 to 10:30
Opening Session

Theme: “150 years since the signing of the Metre Convention and celebration of World Metrology Day 2025”

After some opening remarks from UNESCO, the session will start with speeches by the Permanent Delegations to UNESCO of a number of the Member States of the BIPM. These will welcome the recognition by the UNESCO General Conference in 2023 of World Metrology Day.

•“The Metre Convention of 1875 - an act of multilateral scientific collaboration” – Dr W. Louw (South Africa), President of the International Committee for Weights and Measures (CIPM).
• Reply - Dr B. Mathew (Switzerland), President of the International Committee for Legal Metrology (CIML).

The first session will close with a video of short tributes from the Heads of IOs that work in liaison with the BIPM including IAEA, ITU, WMO, and IFCC.

10:30 ⋅ Coffee break

11:00 to 12:30
Second Session

Theme: “Future challenges for scientific and technical multilateralism, where next for the BIPM and for world metrology?”

This session will discuss future opportunities for the BIPM and for world metrology in the context of the UNESCO International Decade of Sciences for Sustainable Development, 2024–2033.
There will be a series of 10-minute insight talks – then a moderated panel discussion

•“Science diplomacy – a national case study”
• "The challenge of achieving global participation in the Metre Convention”
• “Unleashing Science – delivering missions for sustainability”

The panel will include invited Science Counsellors from Embassies in Paris and the Director-Generals of other scientific/technical IOs plus three invited speakers.

12:30 ⋅ Lunch

14:00 to 15:45 
Third session

Theme: “150 years of the Metric System”

Chaired by Representatives of regional metrology organisations from Africa and the Gulf region

Today’s event was triggered by the decision of 17 States in 1875 to sign the Metre Convention which established the BIPM, one of the first international organisations in the world. Since that time huge steps have been taken to progress the Metric System to address the challenges of today’s technologies and citizens.

• “From the Metric System to the Metre Convention” – Ken Alder, Professor of History and author of “The Measure of All Things”. (Northwestern Univ., USA)
• “The SI – a tool for all mankind” – William Philips, Nobel Prize for Physics in 1997 (NIST, USA)
• “The historic contribution of nations to measurement science”

Questions from the floor for the speakers sitting as a panel.

15:45 ⋅ Tea break

16:30 to 18:00
Fourth Session

Theme: “150 years of support for global metrology”

Chaired by Dr T. Usuda (Japan), Secretary of the International Committee for Weights and Measures (CIPM)

The final session will open with a video of short tributes from former CIPM Presidents and Honorary BIPM Directors. These will be followed by invited talks from global experts on the status of the world measurement system:

• “Expanding the horizon of metrology to chemistry, biology and beyond” – Willie May (AAAS, USA)
•“UTC – a timescale for all the world for all time” Pascale Defraigne, Royal Observatory of Belgium.

Launch of the anniversary book and final video

• “150 years in fifteen photographs” – Dr Martin Milton, BIPM Director

The event will close with a video entitled “Future tasks for the BIPM” with short contributions from “Young Metrologists” selected from every continent.

18:00 ⋅ Close of the day