What is the nature of the universe and what is it made of? What are matter, energy, space and time? How did we get here and where are we going?

Throughout human history, scientific theories and experiments of increasing power and sophistication have addressed these basic questions about the universe. The resulting knowledge has led to revolutionary insights into the nature of the world around us.

In the last 30 years, physicists have achieved a profound understanding of the fundamental particles and the physical laws that govern matter, energy, space and time. Researchers have subjected this 'Standard Model' to countless experimental tests; and, again and again, its predictions have held true. The series of experimental and theoretical breakthroughs that combined to produce the Standard Model can truly be celebrated as one of the great scientific triumphs of the 20th century.

Now, in a development that some have compared to Copernicus's recognition that the earth is not the center of the solar system, startling new data have revealed that only five percent of the universe is made of normal, visible matter described by the Standard Model. Ninety-five percent of the universe consists of dark matter and dark energy whose fundamental nature is a mystery. The Standard Model's orderly and elegant view of the universe must be incorporated into a deeper theory that can explain the new phenomena. The result will be a revolution in particle physics as dramatic as any that have come before.

Nine interrelated questions define the path ahead.
1. Are there undiscovered principles of nature: new symmetries, new physical laws?
2. How can we solve the mystery of dark energy?
3. Are there extra dimensions of space?
4. Do all forces become one?
5. Why are there so many kinds of particles?
6. What is dark matter? How can we make it in the laboratory?
7. What are neutrinos telling us?
8. How did the universe come to be?
9. What happened to the antimatter?

>from *Quantum Universe: The Revolution in 21st-Century Physics*. A report by an ad-hoc committee of the HEPAP (High Energy Physics Advisory Panel), charged by the US Department of Energy and the National Science Foundation. Published by Interactions.org, a central resource for communicators of particle physics. The Interactions.org web site was developed and is jointly maintained by the InterAction collaboration, whose members represent the world's particle physics laboratories in Europe, North America and Asia, with funding provided by science funding agencies of many nations.

related context
> illuminating the darkness. interview with persis drell, research director at stanford linear accelerator center, one of the physicists who wrote the report. june 1, 2004
> space/time atoms?: quantum gravity-based universe. 'the tiny scale at which the microscopic structure of space and time becomes observable is the planck scale.' february 26, 2003
> space, time and beyond: symposium of science, technics and aesthetics. with the comment 'does time really exist as a fourth dimension of space-time? by amrit sorli. january 20, 2003
> mirror matter in the solar system? a dark matter candidate. 'mirror matter is an entirely new form of matter predicted to exist if mirror symmetry is a fundamental symmetry of nature.' november 18, 2002
> in search of extra dimensions: beyond the standard model. 'somewhere within the planck scale, or at extreme energy levels, an incredibly small extra dimension may finally combine gravity and electromagnetism.' february 20, 2002
> center for cosmological physics: probing phenomena beyond standard model. 'in the area of astrophysical cosmology we do have clear signs of new phenomena, new physics beyond the standard model.' september 13, 2001
> working neutrino telescope: a novel way of seeing universe. 'neutrino telescopes are designed to look not up, but down, through the earth to the sky to detect high-energy neutrinos. a critical step toward establishing a new field of astronomy, neutrino astronomy, has been done.' may 22, 2001
> signatures of the invisible: an art exhibition inspired by particle physics. 'this exhibition is made by artists inspired by their experiences of a particle physics laboratory. a collaboration between artists and physicists which has the potential to help redefine the relationship between science and art.' may 8, 2001
> first direct evidence for tau neutrino. 'this completes the picture of the elementary constituents of matter, in accordance with current scientific theory: the standard model, that explains the fundamental particles -what the world is made- and the fundamental forces -what holds the world together-.' july 21, 2000
> prize for pioneers of neutrino astronomy. 'for pioneering observations of astronomical phenomena by detection of neutrinos, which created the emerging field of neutrino astronomy.' may 21, 2000
> first "map" of dark matter. 'while dark matter makes up at least 90% of the mass of the universe, both its composition and its distribution are unknown.' march 7, 2000

imago
> quantum univers book

Nature 415, 969 - 971 (28 February 2002); doi:10.1038/415969a

High-energy physics: The mass question

EDWARD WITTEN

Edward Witten is at the School of Natural Sciences, Institute for Advanced Study, Olden Lane, Princeton, New Jersey 08540, USA.
e-mail: witten@ias.edu

Do the elementary particles known as neutrinos have mass? Yes, according to recent experiments. But how much? A surprising — and controversial — result suggests that the answer is not what we thought.

Neutrinos were long believed to be, like photons, massless particles that always travel at the speed of light. In the past few years, by studying neutrinos emitted by the Sun or created by cosmic rays in the Earth's atmosphere, physicists have learned that neutrinos actually have tiny but non-zero masses, roughly ten million times smaller than the mass of an electron. These masses are believed to result from physical processes occurring at energies well beyond those of known particle interactions. In Modern Physics Letters A, Klapdor-Kleingrothaus and colleagues1 now claim to have observed a new type of nuclear decay process. If this somewhat controversial finding holds up, it implies that the three types of neutrino have almost the same mass, and gives us a window on physics that goes far beyond our present knowledge.

To put the mass of the neutrino in context, consider the mass of other elementary particles. The electron, for example, is about 1,800 times lighter than the proton or neutron, and about 200,000 times lighter than the heaviest known elementary particles, which are the W and Z bosons and the top quark (Fig. 1). Why these masses vary so much is a mystery, even in the modern standard model of elementary particles. By contrast, until recently, neutrinos seemed to be massless, and in the 1950s physicists thought they had worked out why.

"neutrino"="dark matter"

"neutrinos interactions"="dark energy"

According to string theory, all the different particles that constitute physical reality are made of the same thing--tiny looped strings whose different vibrations give rise to the different fundamental particles that make up everything we know. Whether this theory correctly portrays fundamental reality is one of the biggest questions facing physicists.

Theoretical physicists propose the most viable test to date for determining whether string theory is on the right track. The effect that they describe and that could be discovered by LIGO (Laser Interferometer Gravitational-Wave Observatory), a facility for detecting gravitational waves that is just becoming operational, could provide support for string theory within two years. From "Newly devised test may confirm strings as fundamental constituent of matter, energy. Experimental verification would mean more spatial dimensions exist." June 11, 2004
http://www.eurekalert.org/pub_releases/2004-06/uocs-ndt061004.php

search for gravity waves: another window into the universe. december 10, 2001
http://www.straddle3.net/context/01/blog_0112.en.html#10