REPORTS ON PROGRESS IN PHYSICS doi:10.1088/0034-4885/70/6/R01
Fundamentalist physics: why Dark Energy is bad for astronomy
Simon D M White Max Planck Institute for Astrophysics, Garching bei M¨ nchen, Germany u Received 19 March 2007, in ﬁnal form 10 April 2007 Published 16 May 2007 Online at stacks.iop.org/RoPP/70/883
AbstractAstronomers carry out observations to explore the diverse processes and objects which populate our Universe. High-energy physicists carry out experiments to approach the Fundamental Theory underlying space, time and matter. Dark Energy is a unique link between them, reﬂecting deep aspects of the Fundamental Theory, yet apparently accessible only through astronomical observation. Large sections of the twocommunities have therefore converged in support of astronomical projects to constrain Dark Energy. In this essay I argue that this convergence can be damaging for astronomy. The two communities have different methodologies and different scientiﬁc cultures. By uncritically adopting the values of an alien system, astronomers risk undermining the foundations of their own current success andendangering the future vitality of their ﬁeld. Dark Energy is undeniably an interesting problem to tackle through astronomical observation, but it is one of many and not necessarily the one where signiﬁcant progress is most likely to follow a major investment of resources. (Some ﬁgures in this article are in colour only in the electronic version)
This article was invited by Professor J Silk.0034-4885/07/060883+15$90.00 © 2007 IOP Publishing Ltd Printed in the UK 883
S D M White
1. 2. 3. 4. 5.
HST and WMAP The two cultures Dark Matter and Dark Energy So why is Dark Energy bad for astronomy? What is to be done? Acknowledgments
Page 885 888 890 891 895 897
Why Dark Energy is bad for astronomy
The pursuit of a deeper truth, of a fundamental theory whichunderlies all others, is a powerful motivator in physics. So too are curiosity and awe at the richness of Nature, at the connectedness which allows disparate and seemingly unrelated processes to produce order, beauty and diversity from apparent chaos. The ﬁrst motivation is, perhaps, most evident in high-energy physics, where a ‘theory of everything’ has periodically appeared within reach,occupying many of the most talented theoreticians. The second is evident in more interdisciplinary, less ‘fundamental’ ﬁelds, solid-state physics, evolutionary biology or astrophysics. Fundamentalists prize the depth of their research, seeing it as a means to abstract from the complexity of the world a Truth which embodies the ultimate foundation of the physics of particles and ﬁelds, thus, by extension,of all physics, chemistry and biology. Generalists, on the other hand, prize breadth and interdisciplinarity which promote the perception and appreciation of the many truths underlying complex phenomena. In their view, the fundamental theory of everything will contribute nothing to our understanding of the origin and nature of life. The discovery of Dark Energy, a near-uniform ﬁeld which appearsto dominate the energy density of the current Universe and to drive its accelerated expansion, has led astrophysicists and high-energy physicists to make common cause. The apparent properties of the Dark Energy, in particular the extremely low associated energy scale, are entirely unexpected in the standard model of particle physics and extensions such as supersymmetry. This suggests to many thatDark Energy may somehow reﬂect the uniﬁcation of gravity with the other fundamental forces, and hence, paradoxically, physics at energies far above those that can be probed directly with accelerators. At present it seems that the properties of Dark Energy can be explored only through astronomical observations, in particular through precise measurements of the recent expansion history of the...