...plus a wonderful interview with Nima about HEP and failures of science popularization at the end...
Sheldon Glashow, a co-father of the electroweak theory, wrote a 6-page essay about
He offers his personal views on different kinds of experiments and different things they may try to determine, especially those that have a big chance to be performed primarily in the U.S.
I agree with his comments on high-precision experiments. He says that while some progress in physics may result from measuring some parameters more accurately than before, it's often the case that the "next digit" is the only thing we learn. It's an important thing to keep in mind. Even if such a high-precision experiment finds some discrepancy, it won't really make us sure that the discrepancy is due to something else than our error; and it won't tell us what new effect it is really due to if it is not just our error.
Quite generally, the most important transformative revolutions came from the people and experiments who were looking into places that no one else had visited before. I couldn't agree more. There are exceptions, too.
Glashow mentions the experiments focusing on dark energy and dark matter. The direct detection of the latter would be a breakthrough.
The next topic are possible violations of the conservation laws for the baryon number \(B\) and the lepton number \(L\). This topic also covers the likely Majorana character of the neutrino masses. A related topic are flavor-changing processes followed by electric dipole moments of elementary particles.
Glashow has dedicated much of his time to neutrino oscillations in the recent decade or so. He mentions this theme, too. The determination whether the sterile neutrinos exist; whether there is any CP-violation in the neutrino sector; and some information about the neutrino masses are his three key things he want to learn.
The fingers aren't Glashow's; they belong to Kenneth Lane.
It's all serious physics but I don't believe that Glashow doesn't feel that all these things are relatively unimportant technical details in the grand scheme of things. I would say if you remove at most 1 or 2 exceptions, the combined importance of all the questions that Glashow wants to be answered would still be lower than the importance of (just) his own contributions to the electroweak theory.
In fact, I think that the combined importance is also lower than the research of grand unification that Glashow has co-fathered as well, despite the very limited tools to study grand unification experimentally.
In other words, I think that it must be clear to Glashow that the truly important things in high-energy physics happen in research that is not confined to questions that can be answered by existing experiments or the experiments in the near future. One may be used to a pretty good synchronization of advances in theory and experiments but let me tell you something: this synchronization has always been far from perfect; and it is inevitable that the deviation from the perfect synchronization is growing and has to be growing. This growth seems almost as inevitable as the second law of thermodynamics.
While the divorce may be frustrating, it's a part of progress and a sign of progress that we may successfully answer questions that are extremely far from our abilities to directly experimentally test them; and on the contrary, we may perform experiments whose results may be hard to calculate (which is why most of these experiments may be considered to be "irrelevant mess" by the theorists). The increasing separation is inevitably linked to the ability of theorists to think about the natural phenomena ever more cleverly and indirectly; and to the experimenters' ability to test things well beyond those that seem simple to the theorists.
So I believe that the topics Glashow wants to focus on are already representing just a tiny percentage of the questions that are being legitimately asked and researched in high-energy physics and they're really narrow-minded technical details; and their relative importance is guaranteed to decrease in the future, too. In some sense, all the questions generalize the "another digit" type of discoveries and by its unambitious nature, Glashow's vision of the future therefore resembles the vision formulated by Lord Kelvin – we must just measure quantities in classical physics more accurately – before the relativistic and quantum revolutions took place.
The truly important things are different and to sort many of these things, we may use our brains and experiments in ratios that are extremely far from 50:50. There is really no good reason why the composition should always be close to 50:50. By thinking otherwise, Glashow is confining himself into a narrow-minded world governed by irrational quotas and by indefensible dogmas about "the only way to do physics" that result from these quotas.
In reality, people want to answer – and pretty much have the theoretical capacity to answer – many questions about the existence of grand unification, the details of cosmic inflation, the scale and other details surrounding baryogenesis, the black hole information puzzle, the diversity of the landscape and possible vacuum-selection mechanisms in the early cosmology, and others (I don't even want to irritate some readers with some much more abstract and fundamental questions about string theory that remain open). Glashow's attempts to remove these clearly physical questions from physics just because it's hard to measure them today (or in the near future) are preposterous and provincial.
And that's the memo.
Bonus: If you have 100 minutes, you should watch this 6-week-old conversation of Ideas Roadshow (Howard Burton, also a co-founder of the Perimeter Institute) with Nima Arkani-Hamed on the power of principles. Nima also talks about tasty sausages, about the reasons he hasn't written a popular book, about the Academia as a big industry and a bubble (that people including himself – he says – are riding), about his frustration what isn't communicated about science (the divide between the research and the popularization is wider than it has ever been; popularization counterproductively focuses on the latest results/fads instead of the accumulated wisdom – I totally agree; Nima is a big fan of Feynman's Messenger Lectures), about his own lectures at Cornell.
They also or mainly discuss how wrong pictures are often conveyed by popular books, about the wrong timing of Brian Greene's The Elegant Universe, how we learned that strings weren't that fundamental after 1985 (totally agreed), how dualities denying the previous philosophy became the #1 issue (totally agreed with the claim; but I mostly disagree that The Elegant Universe  is picturing string theory of the 1980s if this is what Nima wants to say: it has lots and lots on dualities, M-theory, transitions, general facts on SUSY etc.), how fields and their excitation/particles aren't fundamental (although the popular literature repeats those things all the time), how the philosophy of the science process is still the same as it was during Galileo's and Newton's time (despite the claims in the popular literature: totally agreed again), how the uniqueness and ridigity of the theoretical structures isn't conveyed (totally agreed), how Nima learned a lot from the First Three Minutes, what his daily job looks like (the laymen seem to be confused what's happening in physics departments), and so on.
Nima is bothered by claims like "science is culture" [Seed] because it's either vacuously true (everything humans do "is" culture) or profoundly false: science looks for eternal things and is independent of culture (fully agreed). Unlike human arguments, (well-defined enough) things in science are objectively right or wrong. Nima also correctly emphasizes that the principles inevitably lead to the important conclusions. There's almost nothing to adjust about physics; QM and relativity determine things almost uniquely. The theories are both rigid and fragile (break down when modified) and it's the first time we have a theory of nearly everything and we may divide things we understand from those we don't. Nima also refers to various Leesmolins and others who invent leprechauns (without giving names) and says that in genuine science, it's almost impossible to propose really new things that aren't immediately falsified (I agree with everything in this paragraph). The reason the public isn't getting these things is that they're just not being offered (except for Weinberg's books etc.).
Arkani-Hamed is annoyed by people's statements that fields are fundamental and particles are their excitations; only particles are being measured. I disagree with Nima here; fields and particles are exactly equally real and exactly equally fundamental. We may measure not just particles; we may also measure the fields (and various functionals of theirs). In contrast with Nima's proclamations, there is a photon field. It's called the electromagnetic field, stupid. We may measure the intensity of the magnetic field at a given point which is something else than measuring the number of photons in a state. The equal validity of these viewpoints is really what Bohr's complementarity (or wave-particle duality) is about. It sounds like Nima is trying to constrain what we can measure; but every Hermitian operator is a good enough observable and many of them can simply be formulated naturally in terms of field operators only. Of course that I agree with him that there may be many different field theory Lagrangians with different fields that yield the same physics, however. But that doesn't mean we can't talk about the fields or measure them.
Nima says that the nature of the incompatibility between gravity and quantum mechanics is being misrepresented. Despite people's claims, we can say the things in the same sentence. The problem is that we don't know what's happening at short distances. Totally agreed. He also says that one can experimentally test theories without doing any new experiment – relativity and quantum mechanics are so constraining, powerful proxies of our empirical knowledge that they kill almost all candidate theories. Totally agreed. For example, all decent physicists have known for decades that the Higgs boson had to exist. Agreed. He talks about the near-uniqueness of possible particles' spins up to 2. See this article of mine. For the Higgs mechanism, only spin-0 particles are OK.
He discusses the conservative radicalism vs radical conservatism (try to extrapolate what you know as far as you can; the latter is preferred). We often determine that the principles of Nature allow certain things we haven't seen yet; the Higgs prediction is an example. People are similarly excited by SUSY; Nima is as frustrated as myself by the public discussions presenting SUSY as another leprechaun. For Nima, SUSY is a part of Nature – the last thing in a list of things that Nature can do. Agreed. 3/2 is the last missing spin.
The interviewer is visibly skeptical about these claims. Nima is asked when he would admit that SUSY is wrong. For SUSY "anywhere, at any scale", Nima would be willing to bet many years of salary. For SUSY at the LHC, it's one of the most plausible things but he wouldn't sacrifice an annual salary for that. At any rate, SUSY is existing somewhere. It's important we know it. Totally agreed.
At 1:08:00, they start to talk about the (bogus) superluminal neutrinos claims. For Nima, the episode shows how good science works, how crappy science works, and how muddy is the picture of science in the general public. So he is saying some important things that got less attention than the shoddy sensationalism. The orthodox physicists (like myself) were described as those who are afraid to challenge the authorities blah blah blah. Everyone really wants to discover such things; ideas about the will to suppress them are rubbish, he says. (Agreed with everything.) There had been a whole sub-industry analyzing how you could work for Lorentz violations – Coleman, Glashow, Kostelecký etc. Parameterization of the violations. And, on the other hand, the search for a possible theoretical justification. Nothing has worked here. Totally agreed. Black holes with Lorentz violation violate the laws of thermodynamics. So while the shoddy journalists were saying that Nima, me, and others haven't considered the possibility that Einstein was wrong, the truth was exactly the opposite: we have thought about this possible failure of Einstein so much and so carefully that we simply new it wasn't possible for such a strong violation to exist.
Why so much misinformation? Partly because of the incompetent theorists like Leesmolins who haven't thought about these things carefully and they were encouraging the bullshit ideas about the violations' being possible. These junky papers claimed that a supernova constraint on the Lorentz violations was the only one. But that was very far from being the case. The story about the reasons why we were certain didn't get out at all. Next time, the message should probably convey the idea that rebellious ideas is how the physicists create their names (even by moderately rebellious ones); but credible physicists still have to work within a strongly constraining straitjacket. It seems incredibly unlikely that we will be proven as wrong as Ptolemy.
Quantum mechanics won't be proven wrong but in some questions (cosmology etc.), it seems impotent and a Viagra for that problem will have to be found. He would love to understand why QM and relativity are both fighting against each other so much (barely compatible); and they lovingly co-operate with one another, too.
Nima is asked what he is passionate about now. It's a decade of experimental buzz – the LHC, dark matter searches etc. – which is a new situation. By 2015-2017, he will be willing to bet a year's salary about an answer to the nature of the hierarchy problem. Spacetime is doomed; Nima talks about the twistor-related research. What to do without the spacetime? You need a handle, not just nihilism, and to isolate it is hard. A cool thing about the truth is that it is an attractor: just sit nearby and don't be afraid of it. Nature is a friend of people with vastly different talents.
He talks about a thought experiment: in the early 20th century, you're visited by a ghost who tells you that by 1930, determinism would be gone. What would you do with this divine information? A straightforward physicist would probably just add random non-deterministic terms into the equations and he would get nothing else than some generic leesmolinian stinky crap. That's because the conservative radicalism doesn't really work. It's hard to envision what the whole new framework should look like. You need to invent the Hilbert spaces and all the postulates "simultaneously". Unlikely. The right approach is to ask how I explain the physics that I think we understand in terms of the new non-deterministic framework. You could try to generalize the least-action principle and perhaps invent the path integral which actually makes the existence of the least-action formulation of classical physics more comprehensible.
Holography etc. are the culmination of the 20th century physics (advertisement for string theory colleagues at IAS). We have to find out how to replace the beef of physics after the spacetime is doomed – the spacetime has to emerge without being put in advance. This process could be analogous to the story of the least action and the path integral. The simplification of the complicated numerous Feynman diagrams in the twistor-related uprising is a big hint – new mathematical structures are being discovered. Totally new ways to talk about established physics – which doesn't put the usual starting points as input (locality and unitarity aren't manifest from the beginning) – is perhaps emerging. We need to understand the plethora of the theoretical data as deeply as we can; Einstein was finally doing the things in the same way.
Via Plato Hagel.
A typical American tourist who visited Prague today was shot by a tweeting paparazzo with a Polish name, Lukasz Porwoll. He went to the Charles Bridge (the picture is from the Lesser Town Bridge Tower, hi-res) and McDonald's. They witnessed a pro-gay-activist-Putna rally at the Prague Castle. It seems that no one cared about them or interacted with them. Note that similar American tourists aren't wealthy enough to afford a more respectable shirt for the historical city. If you want to contribute to him and his madam, use the PayPal pig button at the bottom. Unless I find out that the poor chap is a billionaire or something of the sort, I will send him the money.
The photograph above first appeared on Twitter, then in the Czech newspapers, then on The Reference Frame, and much later on various assorted blogs such as Facebook.