Physics in the LHC Era

by Paul Gilster on January 28, 2010

It was in 1900 that mathematician David Hilbert created a list of the most significant unsolved problems for mathematics at a conference in Paris. The list would eventually be fleshed out to reach a total of 23 problems. Hilbert’s Paris talk, “The Problem of Mathematics,” began this way:

Who among us would not be happy to lift the veil behind which is hidden the future; to gaze at the coming developments of our science and at the secrets of its development in the centuries to come? What will be the ends toward which the spirit of future generations of mathematicians will tend? What methods, what new facts will the new century reveal in the vast and rich field of mathematical thought?

The Wikipedia entry on Hilbert notes that the 23 problems, fewer than half of which were presented at the meeting, have gone on to be discussed throughout the following century, with some remaining unresolved to this day. I look at Hilbert’s introduction and think about how apropos the idea of gazing at ‘coming developments of our science’ is to what we do here. Maria Spiropulu, a senior scientist at CERN near Geneva, used Hilbert when talking to the New York Times‘ Dennis Overbye about a weekend conference that recently concluded in Los Angeles. The Physics of the Universe Summit had a grand title, and Spiropulu hoped to use it to “…set out the questions for the next nine decades.”

Now, of course, we have the Large Hadron Collider, which offers the chance to create conditions similar to those existing in the earliest moments of the universe. The trick is in making sense out of what it may show us. Lisa Randall (Harvard) pointed to Galileo’s maxim that physics progresses more when working on small problems than talking about large ones, which could be taken as a way of saying that no matter how elegant a theory may be, it often runs into problems when we get into the details. Supersymmetry, for example, could explain things like dark matter, but Randall points out that no supersymmetric effects have turned up yet as deviations in the Standard Model of physics. Randall believes they should have.

Overbye’s article on the Summit lays out its interesting methodology:

Organized into “duels” of world views, round tables and “diatribes and polemics,” the conference was billed as a place where the physicists could let down their hair about what might come, avoid “groupthink” and “be daring (even at the expense of being wrong),” according to Dr. Spiropulu’s e-mailed instructions. “Tell us what is bugging you and what is inspiring you,” she added.

Adding to the air of looseness, the participants were housed in a Hollywood hotel known long ago as the ‘Riot Hyatt,’ for the antics of rock stars who stayed there.

The eclectic cast included Larry Page, a co-founder of Google, who was handing out new Google phones to his friends; Elon Musk, the PayPal electric-car entrepreneur, who hosted the first day of the meeting at his SpaceX factory, where he is building rockets to ferry supplies and, perhaps, astronauts to the space station; and the filmmaker Jesse Dylan, who showed a new film about the collider. One afternoon, the magician David Blaine was sitting around the SpaceX cafeteria doing card tricks for the physicists.

Wish I were a friend of Page’s — I could use a Nexus One! This is a lively bunch and ideas must have been flying. Gordon Kane (University of Michigan) opined that the Large Hadron Collider would indeed discover supersymmetry but offered no explanations that would point to a theory of dark energy. One big question at a time. Overbye quotes Lawrence Krauss (Arizona State) on the matter of theories and their application, and this, too, is entertaining:

“We get the notions they are right because we keep talking about them,” he said. Not only are most theories wrong, he said, but most data are also wrong — at first — subject to glaring uncertainties. The recent history of physics, he said, is full of promising discoveries that disappeared because they could not be repeated.

Physics can take us from optimism to pessimism in a heartbeat. Are we on the verge of discovering a true ‘theory of everything?’ Or are we likely to be more confounded with each new assault on the secrets of the universe? We haven’t a clue how to explain dark energy, and dark matter remains undetected. For that matter, as Overbye notes, we’ve assumed that dark matter is a kind of particle. What if, instead, it is an ‘entire spectrum of dark behaviors’? Are there forces as well as particles on what these physicists are calling the ‘dark side’?

No answers here, but plenty of questions, in keeping with Dr. Spiropulu’s wish to emulate Hilbert. As a series of investigative doors wide open to the 21st Century, the topics discussed here lead to both exhilaration and confusion. We’ve seen much the same thing occurring in the exoplanet hunt, where we hardly thought we’d find anything as outrageous as planets orbiting a pulsar, or ‘hot Jupiters’ existing breathtakingly close to their stars. The trick seems to be to build the tools that let us push farther and deeper into nature, without prejudging what we will find. ‘Prepare to be surprised’ is as good a motto for today as any.

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{ 12 comments }

David W January 28, 2010 at 18:07

Paul That is why Icarus and Fusion and Sails are so Important.
We may not solve these very very hard Physics issues this century -Science does slow at times BUT no reason not to launch an Interstellar mission this century !
Thanks to all the Icarus team

Darrell E January 29, 2010 at 10:05

That sounds like a fantastic conference. I would love to participate in, more like observe, something like that. Lot’s of new collaborations and interesting lines of investigation can come out of something like this. Most won’t go anywhere, but some might!

Adam January 29, 2010 at 23:49

Would love to see confirmation of Large Extra Dimensions come out of the LHC’s data haul. Artificial black-holes, once we learn how to tackle gamma-rays, could be the key to relativistic spaceflight – but we need hard data on the low-mass range. I’m hoping the LHC will show us that making BHs is easier than classical computations imply. If quantum corrections from the LEDs modify the Hawking radiation, then the final stages might not be as catastrophic as currently computed (~5 teraton TNT equivalent.)

ljk April 7, 2011 at 17:44

Has a new particle or force in physics been found at Fermilab?

http://www.math.columbia.edu/~woit/wordpress/?p=3602

ljk September 1, 2011 at 10:58

Is supersymmetry and the Higgs boson in trouble? Could be some exciting times in physics ahead:

http://www.math.columbia.edu/~woit/wordpress/?p=3937

One thing is clear, there are still plenty of new frontiers to discover. Humanity has hardly found all the answers to life, the Universe, and everything.

ljk November 22, 2011 at 12:42

Still no word (yet) from either the Higgs boson or supersymmetry:

http://www.math.columbia.edu/~woit/wordpress/?p=4171

ljk December 2, 2011 at 18:45
ljk December 4, 2011 at 2:33

Any black holes at the LHC?

Jonas Mureika, Piero Nicolini, Euro Spallucci

(Submitted on 24 Nov 2011)

We introduce analytical quantum gravity modifications of the production cross section for terascale black holes by employing an effective ultraviolet cut off $l$. We find the new cross sections approach the usual “black disk” form at high energy, while they differ significantly near the fundamental scale from the standard increase with respect to $s$.

We show that the heretofore discontinuous step function used to represent the cross section threshold can realistically be modeled by two functions representing the incoming and final parton states in a high energy collision. The growth of the cross section with collision energy is thus a unique signature of $l$ and number of spatial dimensions $d$.

If these predictions prove to be model-independent, they suggest black hole formation might be virtually impossible for collision energies less than 100 TeV. While no such signals would be observed at the LHC, attention should be focused on ultra-high energy cosmic ray events.

Comments:

10 pages, 1 figure

Subjects:

High Energy Physics – Phenomenology (hep-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics – Theory (hep-th)

Cite as:

arXiv:1111.5830v1 [hep-ph]

Submission history

From: Piero Nicolini [view email]

[v1] Thu, 24 Nov 2011 18:43:30 GMT (38kb)

http://arxiv.org/abs/1111.5830

ljk February 17, 2012 at 22:12

Could Higgs Particle be a Time-Traveling Assassin?

Analysis by Ian O’Neill

Wed Mar 16, 2011 05:07 PM ET

We’ve heard the story; a time traveler goes back in time, killing his grandfather. The upshot is that the time traveler ceases to exist. If the time traveler doesn’t exist, how could he have traveled back in time to kill his grandfather?

This logical paradox is known as the “Grandfather Paradox,” and although it makes for a great science fiction storyline — or a seriously creepy Futurama “Grandma Paradox” adaptation — it is a perplexing conundrum that has physicists scratching their heads.

If it is possible to travel back in time, wouldn’t that cause a tangle in time? If, in the future, something is sent to a date in the past, shouldn’t we already see it? How does the Universe prevent such paradoxes from occurring? If it doesn’t, how can we exist at all?

Enter the Large Hadron Collider (LHC), a particle accelerator that might (might!) become mankind’s first time machine,* thereby helping us find out if we can kill our grandfathers in the past and still exist (or something like that).

“Time machine” is a very loose term in this case, as you couldn’t actually use it to transport yourself through time (although there is a wormhole-LHC-time traveling theory that disagrees with this point), but the LHC might (might!) generate a type of Higgs particle that cuts through time like a hot knife through butter, and its decay particles appear in our universe before its own creation event.

This theory has been formulated by two Vanderbilt University theoretical physicists, Tom Weiler and Chui Man Ho. Stating the obvious, Weiler said that the theory “is a long shot,” but it “doesn’t violate any laws of physics.”

We’ve heard about the devious nature of time-traveling Higgs particles before, but this time the Higgs isn’t traveling back in time to sabotage the LHC, a second Higgs particle — called the “Higgs singlet” — might be generated at the same time as the creation of a “normal” Higgs boson.

Full article here:

http://news.discovery.com/space/could-higgs-go-back-in-time-kill-its-grandfather-110316.html

ljk April 25, 2012 at 15:34

Weinberg on the Crisis of Big Science

Posted on April 21, 2012 by woit

Steven Weinberg has a new article in The New York Review of Books on The Crisis of Big Science, which is based on a talk he gave this past January at the American Astronomical Society meeting in Austin (for some discussion of this, see here and here).

Weinberg is rather gloomy about prospects for particle physics, seeing dim prospects for a new generation of particle accelerators, especially in the US. He goes over the sorry story of the SSC, which he was deeply involved in, and worries that the same thing is happening to the James Webb Space Telescope project. He argues that progress is particle physics will be difficult without going to higher energies:

The discovery of the Higgs boson would be a gratifying verification of present theory, but it will not point the way to a more comprehensive future theory. We can hope, as was the case with the Bevatron, that the most exciting thing to be discovered at the LHC will be something quite unexpected. Whatever it is, it’s hard to see how it could take us all the way to a final theory, including gravitation. So in the next decade, physicists are probably going to ask their governments for support for whatever new and more powerful accelerator we then think will be needed…

That is going to be a very hard sell. My pessimism comes partly from my experience in the 1980s and 1990s in trying to get funding for another large accelerator….

During the debate over the SSC, I was on the Larry King radio show with a congressman who opposed it. He said that he wasn’t against spending on science, but that we had to set priorities. I explained that the SSC was going to help us learn the laws of nature, and I asked if that didn’t deserve a high priority. I remember every word of his answer. It was “No.”…

Full article and links here:

http://www.math.columbia.edu/~woit/wordpress/?p=4605

To quote:

He has similar worries about cosmology:

But cosmology is in danger of becoming stuck, in much the same sense as elementary particle physics has been stuck for decades. The discovery in 1998 that the expansion of the universe is now accelerating can be accommodated in various theories, but we don’t have observations that would point to the right theory. The observations of microwave radiation left over from the early universe have confirmed the general idea of an early era of inflation, but do not give detailed information about the physical processes involved in the expansion. New satellite observatories will be needed, but will they be funded?

ljk May 22, 2012 at 13:03

Higgs Update

Posted on May 21, 2012 by woit

The announcement of new Higgs results from the LHC is now scheduled for about a month and a half from now, July 7th, 9:30 and 10am Melbourne time, at ICHEP2012. The LHC is performing well, with nearly 2.5 fb-1 of integrated luminosity/experiment. With only 2-3 weeks more of data collection before the cutoff for what can be analyzed in time to be made public July 7, one can expect the July announcements to be based on perhaps 4-5 fb-1 per experiment.

Rough estimates show that, combining last year’s 5 fb-1 at 7 TeV and this year’s expected data, if the SM Higgs really is there at 125 GeV, each experiment should see a signal of 4 sigma significance. This is not quite the 5 sigma significance traditionally set for a discovery claim, but very close.

It thus looks possible that a discovery claim will require combining the results from CMS and ATLAS. The LHC Higgs Combination Group has been hard at work for the last couple years, developing methods for combining results from the two experiments. This time, they will be ready to quickly combine all the data from the two experiments, and maybe this will be what gives the 5 sigma needed for CERN to claim discovery. I don’t know what the plan is for when they will be provided with the CMS/ATLAS data, or when they plan to announce a result.

Full article here:

http://www.math.columbia.edu/~woit/wordpress/?p=4710

ljk July 16, 2012 at 17:48

Some of the things the Higgs Boson is likely not to do, including give us FTL propulsion:

http://www.science20.com/science_20/craziest_higgs_stories-91824

I think we will conquer the light speed barrier before humans ever stop making up wild stories and believing them sight unseen, especially when it comes to science.

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