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Physicists shrink plans for next major collider

Large Hadron Collider’s failure to detect new particles beyond the Higgs has eroded the case for Japan’s proposed linear accelerator.

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The Large Hadron Collider (pictured) collides protons, whereas the proposed linear accelerator would smash together electrons and positrons.

Limited funding and a dearth of newly discovered particles are forcing physicists to cut back plans for their next major accelerator project: a multibillion-dollar facility known as the International Linear Collider (ILC) in Japan.

On 7 November, the International Committee for Future Accelerators (ICFA), which oversees work on the ILC, endorsed halving the machine’s planned energy from 500 to 250 gigaelectronvolts (GeV), and shortening its proposed 33.5-kilometre-long tunnel by as much as 13 kilometres. The scaled-down version would have to forego some of its planned research such as studies of the ‘top’ flavour of quark, which is produced only at higher energies.

Instead, the collider would focus on studying the particle that endows all others with mass — the Higgs boson, which was detected in 2012 by the Large Hadron Collider (LHC) at CERN, Europe’s particle-physics lab near Geneva, Switzerland.

Leading particle physicists nevertheless remain upbeat. A 250-GeV machine still has “a convincing physics case”, says Hugh Montgomery at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. He says that it could be upgraded to higher energies in future.

High-energy physicists have been planning a future linear collider for 25 years, but the ILC is now unlikely to see the light of day until at least 2030. They viewed the linear collider as complementary to the LHC, allowing physicists to scrutinize in detail any particles discovered at CERN.

Linear design

The circular LHC smashes together protons, which allows it to reach very high energies (13 teraelectronvolts). But, as composite particles (made of quarks), protons create messy collisions with clouds of debris.

By contrast, the ILC would collide electrons and positrons head on after accelerating them in thousands of superconducting cavities joined end to end. Although yielding lower energies, its collisions — between fundamental particles — would be cleaner and more precise than those in a proton–proton machine.

The international physics community had hoped that Japan would foot much of the estimated US$10 billion needed to realize the original design, after researchers there put forward a proposal to host the facility in October 2012, just after the Higgs discovery. But the Japanese government — deterred by the project’s huge price tag, according to Tatsuya Nakada, a physicist at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland — has not yet made any offer of funding.

That fact, coupled with an absence of any other new particle discoveries at the LHC beyond the Higgs, led the Japan Association of High Energy Physicists in July to propose capping the ILC’s energy at 250 GeV.

Aiming for a higher energy, the association explained, made less sense after data collected by the LHC in 2015 and 2016 showed that any particles outside physicists’ standard model are unlikely to weigh less than 1,000 GeV, and therefore would be out of reach even for a full-scale version of the ILC. However, 250 GeV is high enough to produce large numbers of Higgs bosons, which, the association said, could yield indirect signs of new physics through measurements of their interactions with other known particles. 

Energy debate

This proposed ‘Higgs factory’ has also been endorsed by an international working group responsible for formulating the ILC’s science case, in a paper uploaded to the preprint server arXiv last month1. The ICFA then gave the pared-down collider its thumbs up at a meeting held in Ottawa, Canada, this week.

Not all physicists are enthusiastic, however. John Ellis, a theorist at King’s College London and CERN, maintains that only when operating at around 1,000 GeV will a linear collider provide “a more complete picture of the Higgs”. He acknowledges that costs need to be reined in, but says that in limiting the ILC to 250 GeV, “you are making significant scientific compromises”.

A report uploaded to arXiv last week2 describes three possible layouts for the 250 GeV model (a technical design for the higher-energy ILC was published in 2013). Each requires halving the length of the superconducting electron–positron accelerators, but two of the options retain extra tunnel space to accommodate future upgrades.

Taking into account projected savings from ongoing research into accelerators, the report estimates that the collider’s core construction cost could be reduced by as much as 40% — bringing it down to around $5 billion in 2012 prices. Manpower and detectors would then raise the total to about $7 billion, according to Lyn Evans, an accelerator physicist at CERN who is directing research on the ILC.
Michael Peskin, a theoretical partical physicist at the SLAC National Accelerator Laboratory in Menlo Park, California, and a member of the ILC working group, has no doubt about the value of a Higgs factory. He says that theoretical studies of the Higgs boson and the weak nuclear force — one of the four known fundamental forces — done over the past year have strengthened the case for experimental probes of the Higgs’ interaction strength (the Higgs is required to give the carriers of the weak force finite mass). “The 250-GeV stage is actually more interesting scientifically than we thought,” he says.

The ILC decision now rests with Japan. Evans describes the Japanese government’s ongoing assessment of the linear-collider project as “very long and very frustrating”. But other countries won’t commit money until the host country makes its plans known, he says. “The rest of the world is waiting for the Japanese government to decide,” he says.

Journal name:


  1. Fujii, K., et al. Preprint at (2017).

  2. Evans, L. & Michizono, S. Preprint at (2017).

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  1. Avatar for Pentcho Valev
    Pentcho Valev
    Peter Woit: "I think the worst thing that has happened to theoretical physics over the past 25 years is this descent into ideology, something that has accelerated with the multiverse mania of the last 10-15 years." Correct, except for the number 25 - it should be replaced by 112: Peter Hayes: "This paper investigates an alternative possibility: that the critics were right and that the success of Einstein's theory in overcoming them was due to its strengths as an ideology rather than as a science. The clock paradox illustrates how relativity theory does indeed contain inconsistencies that make it scientifically problematic. These same inconsistencies, however, make the theory ideologically powerful. [...] The gatekeepers of professional physics in the universities and research institutes are disinclined to support or employ anyone who raises problems over the elementary inconsistencies of relativity. A winnowing out process has made it very difficult for critics of Einstein to achieve or maintain professional status. Relativists are then able to use the argument of authority to discredit these critics. Were relativists to admit that Einstein may have made a series of elementary logical errors, they would be faced with the embarrassing question of why this had not been noticed earlier. Under these circumstances the marginalisation of antirelativists, unjustified on scientific grounds, is eminently justifiable on grounds of realpolitik. Supporters of relativity theory have protected both the theory and their own reputations by shutting their opponents out of professional discourse. [...] The triumph of relativity theory represents the triumph of ideology not only in the profession of physics bur also in the philosophy of science." The Ideology of Relativity: The Case of the Clock Paradox Joao Magueijo: "Lee [Smolin] and I discussed these paradoxes at great length for many months, starting in January 2001. We would meet in cafés in South Kensington or Holland Park to mull over the problem. THE ROOT OF ALL THE EVIL WAS CLEARLY SPECIAL RELATIVITY. All these paradoxes resulted from well known effects such as length contraction, time dilation, or E=mc^2, all basic predictions of special relativity. And all denied the possibility of establishing a well-defined border, common to all observers, capable of containing new quantum gravitational effects." Faster Than the Speed of Light, p. 250 Pentcho Valev
  2. Avatar for Pentcho Valev
    Pentcho Valev
    Dead (schizophrenic) science - colliders are not necessary: "...Lorenzo Maccone, of the University of Pavia in Italy, Seth Lloyd at MIT in Cambridge, USA, and Vittorio Giovannetti at the Scuola Normale Superiore in Pisa, Italy. [...] They hope their strategy may make it possible to solve one of the biggest problems in physics: the apparent incompatibility of quantum mechanics, which governs the physics of the very small, and general relativity, which describes the motion of stars and planets. [...] In general relativity, space and time are woven together into a pliable thing called spacetime, but quantum mechanics runs on quaintly separate, classical notions of space and time. And when physicists try to apply the equations of general relativity to the realm of quantum mechanics, those equations spit out nonsense." Big Brother replaced 2+2=4 with 2+2=5: "In the end the Party would announce that two and two made five, and you would have to believe it. It was inevitable that they should make that claim sooner or later: the logic of their position demanded it. Not merely the validity of experience, but the very existence of external reality, was tacitly denied by their philosophy. The heresy of heresies was common sense. And what was terrifying was not that they would kill you for thinking otherwise, but that they might be right. For, after all, how do we know that two and two make four? Or that the force of gravity works? Or that the past is unchangeable? If both the past and the external world exist only in the mind, and if the mind itself is controllable what then?" Einstein replaced Newton's absolute time with spacetime: "Special relativity is based on the observation that the speed of light is always the same, independently of who measures it, or how fast the source of the light is moving with respect to the observer. Einstein demonstrated that as an immediate consequence, space and time can no longer be independent, but should rather be considered a new joint entity called "spacetime." Scientists in Big Brother's world are trying to reconcile 2+2=4 and 2+2=5. Scientists in Einstein's schizophrenic world are trying to reconcile Newton's absolute time and Einstein's spacetime: Natalie Wolchover: "The effort to unify quantum mechanics and general relativity means reconciling totally different notions of time. In quantum mechanics, time is universal and absolute; its steady ticks dictate the evolving entanglements between particles. But in general relativity (Albert Einstein's theory of gravity), time is relative and dynamical, a dimension that's inextricably interwoven with directions X, Y and Z into a four-dimensional "space-time" fabric." Perimeter Institute: "Quantum mechanics has one thing, time, which is absolute. But general relativity tells us that space and time are both dynamical so there is a big contradiction there. So the question is, can quantum gravity be formulated in a context where quantum mechanics still has absolute time?" Pentcho Valev
  3. Avatar for Pentcho Valev
    Pentcho Valev
    Nowadays the conclusion "Physics is dead" is getting more and more explicit - it has even entered popular culture: Leonard: "I know I said physics is dead, but it is the opposite of dead. If anything, it is undead, like a zombie." The problem is theoretical - experimentalists are just misguided: "The Large Hadron Collider is a particle accelerator currently under construction in the research centre CERN. From the point of view of relativity theory, it has several points of interest: First of all, the protons it accelerates will reach higher energies than ever, allowing new tests of the relativistic quantum field theories that are at the core of modern particle physics. Secondly, at such high energies, there should be first traces of an as-yet unproven symmetry of nature called supersymmetry, which plays an important role in string theory, one of the candidates for a theory of quantum gravity (the quantum theory version of Einstein's general relativity). Finally, the high energies are interesting because they give information about the very early high temperature universe, and about the physics that should be included in the big bang models of relativistic cosmology." There is a tenet which, if false, does convert modern physics into a zombie, and this is Einstein's constant-speed-of-light postulate. Here is the original formulation: Albert Einstein, ON THE ELECTRODYNAMICS OF MOVING BODIES, 1905: "...light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body." If interpreted correctly, the Doppler effect directly refutes the postulated independence from "the state of motion of the emitting body". Here is an incorrect interpretation - the postulate is saved by wrongly assuming that the light pulses bunch up in front of the moving source: Albert Einstein Institute: "We will start with a very simple set-up, which you can see in the following animation. On the right-hand side, drawn in green, there is a sender that emits pulses in regular succession. On the left-hand side there is a receiver, drawn in blue. The pulses themselves are drawn in red, and they all travel at the same speed from right to left. Everytime the sender emits a new pulse, a yellow indicator light flashes once. Likewise, a flashing light indicates when a pulse has reached the receiver: Next, let us look at a slightly different situation, where the source is moving towards the detector. We assume that the motion of the sender does not influence the speed at which the pulses travel, and that the pulses are sent with the same frequency as before. Still, as we can see in the following animation, the motion influences the pulse pattern: The distance between successive pulses is now smaller than when both sender and receiver were at rest. Consequently, the pulses arrive at the receiver in quicker succession. If we compare the rates at which the indicator lights at the receiver and at the sender are flashing, we find that the indicator light at the receiver is flashing faster." [END OF QUOTATION] Einsteinians make the following assumption above, which is essentially identical to Einstein's 1905 constant-speed-of-light postulate: Assumption 1: "The motion of the sender does not influence the speed at which the pulses travel." Assumption 1 goes hand in hand with another assumption: Assumption 2: "The distance between successive pulses is now smaller than when both sender and receiver were at rest." Assumption 2 is false - the pulses do not bunch up when the source (sender) is moving. If they did, by measuring the (variable) distance between the pulses, an observer associated with the source would know whether he is moving or at rest, which contradicts the principle of relativity. Since Assumption 2 is false, Assumption 1 is false as well. If the speed of the moving source is v, the speed of the light relative to the receiver is c'=c+v, in violation of Einstein's relativity. The following quotations suggest that, if the speed of light is variable, modern physics is dead: "The speaker Joao Magueijo, is a Reader in Theoretical Physics at Imperial College, London and author of Faster Than the Speed of Light: The Story of a Scientific Speculation. He opened by explaining how Einstein's theory of relativity is the foundation of every other theory in modern physics and that the assumption that the speed of light is constant is the foundation of that theory. Thus a constant speed of light is embedded in all of modern physics and to propose a varying speed of light (VSL) is worse than swearing! It is like proposing a language without vowels." "But the researchers said they spent a lot of time working on a theory that wouldn't destabilise our understanding of physics. "The whole of physics is predicated on the constancy of the speed of light," Joao Magueijo told Motherboard. "So we had to find ways to change the speed of light without wrecking the whole thing too much." Pentcho Valev
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