Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Nobel Prize 2011: Perlmutter, Schmidt & Riess

The 2011 Nobel Prize in Physics has been awarded to Saul Perlmutter, Brian Schmidt and Adam Riess, "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae".

Isn't it annoying when that happens? You set out to prove something and find that, in fact, the opposite is true.

That's what happened to Adam Riess — who shares this year's Nobel Prize with Saul Perlmutter and Brian Schmidt — in the autumn of 1997. He was using data collected by the High-z Supernova Search Team, led by Schmidt, to calculate the mass of the Universe and thence determine whether the Universe would expand forever or eventually collapse. Riess assumed, as everyone always had, that the rate of expansion of the matter-dominated Universe must be gradually slowing under the effect of gravity. But his calculations gave the Universe a nonsensical negative mass1.

Riess and the High-z Supernova Search Team realized that the unexpected dimness of their sample of distant type-Ia supernovae signalled instead that the expansion of the Universe is accelerating2 — as did Perlmutter's Supernova Cosmology Project3, which had begun its painstaking collection of similar supernova data earlier, in 1988. More recently, data on the cosmic microwave background radiation and baryon acoustic oscillations have given further support to the notion of accelerating expansion.

Something is driving the acceleration, and that something is usually referred to as 'dark energy'4. It could be attributed to the cosmological constant, Einstein's much-regretted fudge factor in his field equations of general relativity, or a scalar field that varies in time and space, such as quintessence. Either way, it is now thought to constitute 73% of the stuff of the Universe, dwarfing the 23% that is dark matter and the 4% that is ordinary matter.


The Nobel Prize in Physics 2011


  1. 1

  2. 2

    Riess, A. G. et al. Observational evidence from supernovae for an accelerating universe and cosmological constant.. Astron. J. 116, 1009–1038 (1998).

    ADS  Article  Google Scholar 

  3. 3

    Perlmutter, S. et al. Measurement of Ω and Λ from 42 high-redshift supernovae.. Astrophys. J. 517, 565–586 (1999).

    ADS  Article  Google Scholar 

  4. 4

    Brumfiel, G. A constant problem. Nature 448, 245–248 (2007).

    ADS  Article  Google Scholar 

Download references


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wright, A. Nobel Prize 2011: Perlmutter, Schmidt & Riess. Nature Phys 7, 833 (2011).

Download citation


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing