Discovering the Quantum Universe

By JoAnne Hewett | May 23, 2006 6:07 pm

It’s out! This long awaited report has made its debut! 16 of us spent a large fraction of last summer writing a snazzy report that explains the excitement of 21st-century particle physics to audiences who are not science experts – at the request of folks at DOE and NSF. A somewhat technical version was submitted to the EPP2010 panel, and a less technical version has just been publicly launched at a Congressional R&D caucus amidst great fanfare. Brian Greene of Elegant Universe fame gave the presentation and brought along his buddy, Alan Alda, to smooze with members of Congress. Who said particle physics doesn’t have star power?!

The full title of the report is Discovering the Quantum Universe: the Role of Particle Accelerators. It lays out a realm of possible discoveries that are waiting for us at the higher energies that will be probed at the Large Hadron Collider (LHC), and their relationship to discovery opportunities at the proposed International Linear Collider (ILC). The basic premise is that Particles Tell Stories, i.e., there are two steps in the path to learning how the quantum universe works:

1. Discovery of a new particle
2. Discovery of the theory behind the new particle

Discovery of a new particle, exciting as that would be, is just the opening chapter of a story. The new particles are messengers, and their properties reveal the full story about the nature of matter, energy, space, and time.

The LHC has a broad energy reach and large event rate and will be an excellent tool to sweep out the next energy scale and discover particles. The ILC is a flexible precision machine which can be tuned to isolate the new particles and discover their properties. These properties then reveal the underlying theory which gave rise to the particles. In physicist’s language, combined measurements at the ILC and LHC would allow us to construct the fundamental Lagrangian of the new theory. Only then will we understand how the universe works at the next level.

The report centers on three main themes:

1. Solving the Mysteries of the Terascale: The LHC should discover the Higgs and other new particles. Experiments at the ILC would then zoom in on these phenomena to discover their secrets. Properties of the Higgs may signal extra dimensions of space or explain the dominance of matter over antimatter. Particle interactions could unveil a universe shaped by supersymmetry.
2. Light on Dark Matter: Most theories of Terascale physics contain new massive particles with the right properties to contribute to dark matter. Such particles would first be produced at the LHC. Experiments at the ILC, in conjunction with dedicated dark matter searches, would then discover whether they actually are dark matter.
3. Connecting the Laws of the Large to the Laws of the Small (Einstein’s Telescope): From a vantage point at the Terascale, the ILC could function as a telescope to probe far higher energies. This capability offers the potential for discoveries beyond the direct reach of any accelerator that could be built. In this way, the ILC could bring into focus Einstein’s vision of an ultimate unified theory.

Nine discovery scenarios for the LHC and ILC, following the above themes, are then discussed in more detail. We’ve given them cute names: the Higgs is different, a shortage of antimatter, mapping the dark universe, exploring extra dimensions, dark matter in the laboratory, supersymmetry, matter unification, unknown forces, and a concerto for strings. For each scenario, the report maps out what will be learned from both the LHC and ILC which illustrates the bigger picture of how experiments at the next generation of particle accelerators will address the fundamental questions of the quantum universe.

One of the most challenging aspects of writing the report (at least for me) was to omit the technical jargon in our explanations. Us physicists have a hard time not tossing in words that are unfamiliar to everybody else. For example, we needed to dream up a new name for the energies that will(would) be probed at the LHC(ILC). We call it the TeV scale, scientifically named for the actual energy of 1,000,000,000,000 electron volts. It couldn’t be a more dull or meaningless name to a normal person. After immense brainstorming, we decided on the name the Terascale. It still has scientific meaning, the public is more used to it thanks to terascale computing, and it’s somewhat catchy — we hope. We’ll see if it catches on! Some of the panel members also got to experience a photoshoot – as shown here – with pretty good results I’d say.

It’s good to see the final report released, and now we will see if it does a good job in describing the excitement of particle accelerator science to a more general audience.

CATEGORIZED UNDER: Science, Science and the Media
  • Travis

    I really like the pictures used in the report. They have a such a great ‘feeling’ to them. I don’t really know how to describe that. Very exciting!

  • Zeno

    This is delightful news. Congratulations!

    It sounds as if the folks at DOE were nice enough not to insist on your saying “theory” every time you mentioned the Big Bang.

  • Pyracantha

    Is this a paper book or magazine that you can buy? Or is it a video/DVD or a multimedia presentation available for sale?
    I get SYMMETRY magazine which is a fancy publication that talks about the same things as that report, but I find the texts hard to read because they are so full of acronyms such as SLAC, BNL, LCLS, ILC, LHC, MIPP, KIPAC, NuMI, PULSE, and CDF..
    I know it’s serious science when the acronyms outnumber the words.

  • JoAnne

    Pyracantha, this is a fancy magazine that you can download from the web from the link given above (the link with the words “less technical version”.

  • Amitabha

    I like the name terascale. Perhaps high-energy physics can be renamed terascience? These days nanoscale and nanoscience seem to catch the public imagination quite easily — it would be nice to see terascale gain the same popularity.

  • Paul Valletta

    Very interesting!

    This from page 34:Polarized beams at the linear collider could probe such a scenario by detecting differences in the way the two components of the electron behave. Experimenters would then observe deviations in the polarized scattering of electrons, e+e- L,R to e+e-. The attainable level of precision is more than enough to resolve the locations of the two components of the electron. In this way, the linear collider could map the geography of the standard model particles in the extra dimensions. Such a discovery would require the capability of beam polarization, unique to the linear collider.

    Where particles live in extra dimensions. The
    locations of the two kinds of electron (left- and
    right-handed) in an extra dimension could be measured with the polarized beams of the linear collider. In this figure, the horizontal and vertical scales represent distance along the extra dimension, in units of hbar c / 4 TeV 1/20,000th the diameter of a proton).The
    red and green curves correspond to estimated
    experimental errors of a 0.5 and 1.0 TeV ILC,
    respectively. ILC observations would place
    particles in one of these two colored regions.
    Location of eR in an extra dimension.

    Amazing stuff.

  • citrine

    Great job, JoAnne et al!

    I hope that this report will get a lot of publicity via the popular science press. This is a great way for those involved in scientific research to share their work directly with non specialists. I would really like to see some bright kids in junior high and high schools being motivated by this report to pursue Physics in college.

  • Sean

    “Particles tell stories” is a great motto, and it gets to the heart of the matter: we’re not in it just to find new particles for their own sakes, but because the particles behave in certain ways that reveal how Nature works.

    I’m less convinced about “Terascale” as a user-friendly bit of terminology. “Tera” will indeed have some resonance, but I’m not so sure about “scale,” as people on the street aren’t used to thinking in terms of exploring higher and higher energy scales. But I certainly agree that it’s difficult to convey the importance of understanding TeV-scale physics to non-experts, which is why people so often cheat and talk about the origin of mass etc.

    Great job with the report.

  • Plato
  • Dick

    The LHC will probe that other pitch-black room, the one supposedly containing the twin pitch-black cats of supersymmetry and extra dimensions. Since they don’t exist, it won’t find them. The Higgs is a cat of a different color, and the LHC will probably find it, but there’s a chance that it won’t because the Higgs is not a particle field. (The idea that other particles get mass by bumping into Higgs particles is naïve and silly.) In general, scalar fields are structural fields, not particle fields. It will be interesting to see how true believers justify their continuing faith in string theory after the LHC fails to find supersymmetry and extra dimensions.

  • Mike

    Simple, Dick. Lack of evidence just means that the SUSY energy scale is higher than expected. Same for the extra dimensions. See how convenient that is? Oh, and remember: it’s not string theory, it’s magic theory.

  • JoAnne

    Let me just add that string theory does not predict that the LHC will find Supersymmetry or extra dimensions. String theory merely predicts that the two (supersymmetry and x-tra dims) must exist at the string scale (nominally the Planck scale, but could be lower) or below.

    However, we have other, more compelling, reasons to believe that supersymmetry or extra dimensions, or something of that ilk does exist at the Terascale and that the LHC will find it. New physics is needed to solve the hierarchy problem.

  • JoAnne

    Thanks to all who have read the report and enjoyed it! It’s great to get such positive feedback!

  • Vince

    Why is the hierarchy problem a problem (in the literal sense) in the first place?

  • JoAnne

    Vince: I see you are a physics graduate student – I have no idea which field or how advanced. So let me give you my synopsis of the hierarchy problem in fairly technical language.

    The global set of precision electroweak data indicates that there is a light Higgs-like object (

  • Vince

    Go on…

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